Why Do Cancer Cells Synthesize Their Own Fatty Acids? From the De Novo Fatty Acid Synthesis Pathway to Experimental Assessment

1. How can we determine whether cancer cells depend on synthesizing their own fatty acids?

De novo fatty acid synthesis refers to the process by which cells use small-molecule carbon sources such as glucose, glutamine, and acetate to synthesize fatty acids inside the cell, rather than relying directly on exogenous fatty acid supply. To study whether cancer cells depend on synthesizing their own fatty acids, it is not enough to examine whether related proteins such as fatty acid synthase (FASN) are upregulated. It is also necessary to determine whether carbon sources truly enter fatty acids, whether blocking the pathway affects the cells, and whether exogenous fatty acids can compensate for this effect.

To determine whether cancer cells depend on synthesizing their own fatty acids, the following questions should be answered:

Questions to answer	Experimental significance
1. Are cancer cells actually synthesizing new fatty acids?	Determines whether the pathway has real metabolic flux
2. Does the carbon used for fatty acid synthesis come from glucose or glutamine?	Determines carbon-source dependence and environmental adaptation
3. Does inhibition of fatty acid synthesis affect cancer cell proliferation or survival?	Determines whether the pathway constitutes a functional dependency
4. Can exogenous fatty acids rescue the phenotype after inhibition?	Determines whether the phenotype is truly caused by fatty acid insufficiency
5. Do hypoxia, lipid deprivation, or three-dimensional culture change or enhance this dependency?	Determines whether the experimental results are consistent with realistic tumor conditions

In actual experimental settings, researchers often encounter the following situations:

Experimental observation	Conclusion that cannot be drawn directly	Question that needs to be answered next
FASN is highly expressed in tumor samples	Cancer cells must depend on fatty acid synthesis	Is fatty acid synthesis flux actually increased?
Cell proliferation decreases after FASN inhibition	The target must be specific and effective	Can exogenous fatty acids rescue the phenotype?
Lipid metabolism genes change under hypoxia	The pathway must be activated	Is there glutamine reductive carboxylation, acetate utilization, or compensation by other carbon sources?
The drug effect is weak under conventional culture conditions	The pathway is not important	Do exogenous lipids in serum mask the dependency?

This article mainly discusses how cancer cells convert carbon sources into fatty acids through the ATP citrate lyase (ACLY)–acetyl-CoA carboxylase (ACC)–fatty acid synthase (FASN) pathway, and how to experimentally determine whether this synthesis constitutes a genuine metabolic dependency.

2. Why do cancer cells need fatty acids?

Cancer cells need fatty acids mainly because rapid proliferation requires continuous construction and remodeling of cellular structures.

Uses of fatty acids	Significance for cancer cells	Experimentally observable phenomena
1. Cell membrane synthesis	Cell division requires new plasma membranes and organelle membranes	Enhanced lipid synthesis and increased membrane lipids
2. Protein lipid modification	Some signaling proteins require lipid modification to localize to membrane structures	Sustained activation of growth signals
3. Regulation of membrane properties	Fatty acid chain length and saturation affect membrane fluidity	Changes in the ratio of saturated to unsaturated fatty acids
4. Lipid droplet storage	Excess fatty acids can be stored in lipid droplets as a stress buffer	Increased number or volume of lipid droplets
5. Energy supplementation	Some fatty acids can enter oxidative degradation	Enhanced fatty acid oxidation under nutrient stress

One direct product of de novo fatty acid synthesis is palmitic acid. Palmitic acid can undergo further elongation and desaturation, or be incorporated into complex lipids such as phospholipids and triglycerides.

3. Cancer cells have two sources of fatty acids

Cancer cells mainly obtain fatty acids through two routes: exogenous uptake and endogenous synthesis. These two routes can coexist and may switch depending on the environment.

Source of fatty acids	Main meaning	Impact on experimental results
1. Exogenous uptake	Fatty acids are obtained from serum, lipoproteins, culture medium, or the tumor microenvironment	May mask dependence on de novo fatty acid synthesis
2. De novo synthesis	Fatty acids are synthesized inside the cell from carbon sources such as glucose and glutamine	Isotope tracing is needed to confirm flux

Exogenous fatty acids can also enter the cellular lipid pool. In stable isotope experiments, fatty acids synthesized by the cells themselves carry the label, whereas exogenously taken-up fatty acids usually do not carry that label. This makes it possible to distinguish “self-synthesized” fatty acids from those “taken up from outside.”

3.1 When exogenous fatty acids are abundant

Conventional cell culture often uses serum-containing medium. Serum contains lipids, lipoproteins, and bound fatty acids. In this setting, the following situations may occur:

Situation	Result
Cells can obtain fatty acids from outside	The pressure to perform de novo fatty acid synthesis decreases
FASN is inhibited	The proliferation phenotype may be less obvious
Palmitic acid or oleic acid is supplemented	Cellular stress caused by blockade of the synthesis pathway may be alleviated

3.2 When exogenous fatty acids are insufficient

When lipid-depleted serum, low-nutrient culture, three-dimensional spheroids, organoids, or hypoxia models are used, cancer cells are more likely to reveal their dependence on de novo fatty acid synthesis.

At this point, the following should be examined carefully:

1. Whether FASN expression is increased;

2. Whether glucose- or glutamine-derived carbon enters fatty acids;

3. Whether inhibition of ATP citrate lyase (ACLY), acetyl-CoA carboxylase (ACC), or fatty acid synthase (FASN) affects proliferation;

4. Whether exogenous fatty acid supplementation can rescue cell growth.

4. How does the ATP citrate lyase–acetyl-CoA carboxylase–fatty acid synthase pathway operate?

The core axis of de novo fatty acid synthesis is:

ATP citrate lyase (ACLY) → acetyl-CoA carboxylase 1 (ACC1) → fatty acid synthase (FASN)

The de novo fatty acid synthesis axis discussed in this article mainly centers on ACC1. ACC2 can also generate malonyl-CoA, but its role is more closely related to the regulation of fatty acid oxidation.

4.1 Division of labor among the three key enzymes

Key enzyme	Main function	Question answered in experiments
1. ATP citrate lyase (ACLY)	Converts cytosolic citrate into acetyl-CoA	Whether glucose metabolism or glutamine metabolism is connected to fatty acid synthesis
2. Acetyl-CoA carboxylase 1 (ACC1)	Converts acetyl-CoA into malonyl-CoA	Whether the substrate for fatty acid chain elongation is generated
3. Fatty acid synthase (FASN)	Uses acetyl-CoA and malonyl-CoA to synthesize palmitic acid	Whether the fatty acid assembly process is being carried out

During de novo fatty acid synthesis, acetyl-CoA carboxylase 1 (ACC1) generates malonyl-CoA, and fatty acid synthase (FASN) further uses acetyl-CoA and malonyl-CoA to produce long-chain fatty acids. This process also requires reduced nicotinamide adenine dinucleotide phosphate (NADPH) as a source of reducing power.

4.2 Glucose-driven fatty acid synthesis pathway

Glucose → pyruvate → mitochondrial acetyl-CoA → citrate → cytosolic acetyl-CoA → malonyl-CoA → palmitic acid

Corresponding key nodes:

Node	Key reaction
1. Glucose to pyruvate	Glycolysis provides the carbon source
2. Pyruvate to acetyl-CoA	Acetyl-CoA is generated inside mitochondria
3. Acetyl-CoA to citrate	Citrate is formed through the tricarboxylic acid cycle
4. Citrate to cytosolic acetyl-CoA	Catalyzed by ATP citrate lyase (ACLY)
5. Acetyl-CoA to malonyl-CoA	Catalyzed by acetyl-CoA carboxylase 1 (ACC1)
6. Malonyl-CoA to palmitic acid	Catalyzed by fatty acid synthase (FASN)

4.3 Pathway by which glutamine supports fatty acid synthesis

Glutamine → glutamate → α-ketoglutarate → isocitrate/citrate through reductive carboxylation → cytosolic acetyl-CoA → fatty acids

Under hypoxia, restricted mitochondrial oxidation, or enhanced hypoxia-inducible factor-related signaling, glutamine can generate citrate through reductive carboxylation and continue to support lipid synthesis.

5. When do cancer cells depend more strongly on synthesizing their own fatty acids?

Whether cancer cells depend on synthesizing their own fatty acids depends on exogenous lipid supply, oxygen conditions, mitochondrial function, and proliferative pressure.

Scenario	Metabolic characteristics	What should be examined experimentally
1. Rapid proliferation	Increased demand for membrane lipids	Palmitic acid, phospholipids, FASN
2. Insufficient exogenous lipids	Cells rely more on endogenous synthesis	Proliferation changes under lipid-depleted serum
3. Hypoxia	Glucose oxidation is restricted, and the contribution of glutamine may increase	Proportion of labeled glutamine entering fatty acids
4. Impaired mitochondrial function	Reduced ability of oxidative metabolism to generate citrate	Reductive carboxylation and citrate sources
5. Three-dimensional growth environment	Oxygen and nutrient gradients emerge	Pathway dependency in spheroids or organoids

Under normoxia, carbon from glucose can enter the tricarboxylic acid cycle to generate citrate, which is then converted by ATP citrate lyase (ACLY) into cytosolic acetyl-CoA. Under hypoxia, restricted mitochondrial respiration, or impaired tricarboxylic acid cycle function, some cancer cells may increase the proportion of glutamine entering the isocitrate/citrate and acetyl-CoA pools through reductive carboxylation, thereby continuing to support lipid synthesis. This change needs to be confirmed by ^13C-glutamine tracing.

6. Why does “high expression” not prove “metabolic dependency”?

Increased expression of fatty acid synthase (FASN), ATP citrate lyase (ACLY), or acetyl-CoA carboxylase (ACC) only indicates that the cells may have a tendency toward lipid synthesis. It does not directly prove that the cells depend on this pathway.

Observation	What it cannot prove	Additional evidence needed
1. High FASN expression	It cannot prove that fatty acid synthesis flux is increased	Stable isotope tracing
2. Increased ACLY	It cannot prove that cytosolic acetyl-CoA mainly comes from citrate	Carbon-source tracing and metabolite detection
3. Changes in acetyl-CoA carboxylase (ACC)	It cannot prove that fatty acid synthesis is enhanced	Distinguishing ACC1 from ACC2 and examining phosphorylation status
4. Inhibitors reduce cell viability	It cannot prove that the effect comes entirely from the target pathway	Gene knockdown, rescue experiments, and target validation
5. Lipidomics shows changes	It cannot prove that the changes come from de novo synthesis	Combination with labeled glucose or labeled glutamine

Spatial single-cell isotope tracing studies have shown marked heterogeneity in de novo fatty acid synthesis and acetyl-CoA sources among cancer cells. This indicates that a single expression marker or a bulk-average result may obscure real metabolic differences.

7. Experimental validation: using four layers of evidence to determine whether cancer cells depend on synthesizing their own fatty acids

To determine whether cancer cells depend on de novo fatty acid synthesis, it is recommended to proceed through four layers of evidence.

Evidence layer	Question answered	Recommended experiments
1. Expression evidence	Are pathway molecules increased?	Real-time quantitative polymerase chain reaction, Western blotting, immunohistochemistry
2. Flux evidence	Do carbon sources enter fatty acids?	Stable isotope tracing, mass spectrometry, lipidomics
3. Functional evidence	Does pathway inhibition affect cell fate?	Gene knockdown, gene knockout, small-molecule inhibition
4. Rescue evidence	Is the phenotype caused by fatty acid insufficiency?	Supplementation with palmitic acid, oleic acid, or lipid mixtures

7.1 Expression evidence

Detection target	Recommended indicators	Interpretation
1. Nucleic acid level	ACLY, ACACA, ACACB, FASN, SCD1	Determines whether pathway genes are upregulated
2. Protein level	ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase	Determines whether core enzymes are increased
3. Activity state	Phosphorylated ATP citrate lyase and phosphorylated acetyl-CoA carboxylase; phosphorylation results need to be interpreted according to the specific site, especially because AMPK-related ACC phosphorylation usually indicates inhibition of ACC activity	Determines the regulatory state of the pathway
4. Tissue localization	Immunohistochemistry and immunofluorescence	Determines regional differences among tumor cells

The phosphorylation status of acetyl-CoA carboxylase requires cautious interpretation. AMP-activated protein kinase-mediated phosphorylation of acetyl-CoA carboxylase 1 is usually associated with inhibition of its activity. Therefore, increased phosphorylation should not simply be equated with enhanced fatty acid synthesis.

7.2 Flux evidence

Tracing substrate	Question answered	Applicable scenario
1. Uniformly labeled ^13C-glucose	Whether glucose-derived carbon enters palmitic acid or complex lipids	Normoxic models with active glucose metabolism
2. Uniformly labeled ^13C-glutamine	Whether glutamine supports fatty acid synthesis	Hypoxic or mitochondrially impaired models
3. Labeled acetate	Whether acetate replenishes the acetyl-CoA pool through acetyl-CoA synthetase short-chain family member 2 (ACSS2) and related pathways	Models with ATP citrate lyase inhibition
4. Labeled fatty acids	Whether exogenous fatty acids are taken up and incorporated into complex lipids	Studies of exogenous compensation

Key readouts include:

1. Whether labeled carbon enters palmitic acid.

2. Whether labeled carbon enters phospholipids and triglycerides.

3. Whether the contribution of carbon sources changes under normoxia and hypoxia.

4. Whether fatty acid labeling decreases after inhibition of ATP citrate lyase (ACLY).

5. Whether cells reduce their own synthesis after supplementation with exogenous fatty acids.

7.3 Functional evidence

Experimental approach	Purpose	Key points for interpretation
1. FASN knockdown	Determines whether fatty acid assembly is necessary	Proliferation, colony formation, apoptosis
2. ACLY knockdown	Determines whether the source of cytosolic acetyl-CoA is critical	Lipid synthesis flux, cell survival
3. ACC1 inhibition	Determines whether malonyl-CoA generation is critical	Fatty acid synthesis, cell cycle
4. Small-molecule inhibitor treatment	Simulates pharmacological intervention	Dose dependence, time dependence, target specificity
5. Validation in three-dimensional spheroids or organoids	Approximates the tumor tissue environment	Whether results from two-dimensional culture remain valid

ATP citrate lyase inhibition can reduce proliferation and survival in some glycolysis-active tumor cells. Enhanced fatty acid synthesis is also considered an important metabolic feature supporting cancer cell survival and proliferation.

7.4 Rescue evidence

Rescue method	Question answered	Notes
1. Palmitic acid supplementation	Whether the phenotype after inhibition of fatty acid synthesis is related to palmitic acid insufficiency	High concentrations of palmitic acid may cause lipotoxicity
2. Oleic acid supplementation	Whether unsaturated fatty acids can alleviate cellular stress	May promote lipid droplet formation
3. Lipid mixture supplementation	Whether exogenous lipids can provide broader compensation	It is difficult to identify the role of specific fatty acids
4. Albumin control	Excludes carrier-related effects	Fatty acids often need to be added in albumin-bound form

Fatty acid rescue experiments alone cannot prove that cancer cells depend on de novo fatty acid synthesis, but they can help determine whether the cellular phenotype after pathway inhibition is related to insufficient fatty acid supply. A more complete evidence chain is:

Increased pathway expression or activity-related evidence → labeled carbon enters palmitic acid or complex lipids → proliferation, colony formation, or survival is affected after inhibition of key pathway nodes → exogenous fatty acids partially rescue the phenotype.

8. Key Variables to Consider in Experimental Design

Experiments on de novo fatty acid synthesis in cancer cells are sensitive to culture conditions. Factors such as serum lipid content, oxygen concentration, glucose and glutamine supply, cell density, and culture model can all affect fatty acid synthesis flux and the phenotype after inhibitor treatment. Therefore, when designing experiments and interpreting results, these conditions should be clearly recorded, and appropriate controls should be set according to the research question.

Variable	Why it matters	Recommended approach
1. Serum lipid content	Exogenous lipids may mask dependence on endogenous synthesis	Compare regular serum with lipid-depleted serum
2. Oxygen concentration	Hypoxia can alter the contribution of glucose and glutamine	Set normoxic and hypoxic conditions
3. Glucose concentration	Affects glycolysis and citrate sources	Clearly define the glucose concentration in the culture medium
4. Glutamine concentration	Affects reductive carboxylation and anaplerotic reactions	Set glutamine-replete and glutamine-limited conditions
5. Cell density	High density changes nutrient consumption and lipid demand	Keep the initial seeding density consistent
6. Culture model	Two-dimensional and three-dimensional models differ in metabolic state	Validate key results in three-dimensional models
7. Inhibitor specificity	A single drug may have off-target effects	Validate with gene knockdown or knockout
8. Fatty acid supplementation method	Free fatty acids may cause nonspecific toxicity	Use albumin-bound fatty acids and set carrier controls

9. How should common results be interpreted?

Experimental result	Reasonable interpretation	Next experiment
1. Fatty acid synthase (FASN) is highly expressed, labeled glucose enters fatty acids at a high level, and proliferation decreases after inhibition	Cancer cells may depend on glucose-driven de novo fatty acid synthesis	Perform fatty acid rescue and validation in three-dimensional models
2. Fatty acid synthase (FASN) is highly expressed, but little labeled glucose enters fatty acids	Expression and flux are inconsistent; the cells may depend on exogenous fatty acids	Examine fatty acid uptake and the influence of serum lipids
3. The inhibitory effect is weak under normoxia but strong under hypoxia	Hypoxia may enhance dependence on fatty acid synthesis or change the carbon source	Add labeled glutamine tracing
4. The inhibitory effect is enhanced in lipid-depleted serum and restored after fatty acid supplementation	Exogenous lipid supply determines the strength of pathway dependence	Compare palmitic acid, oleic acid, and lipid mixtures
5. Lipid synthesis decreases after ATP citrate lyase (ACLY) inhibition, but cells remain viable	Cells may have alternative acetyl-CoA sources or compensation from exogenous lipids	Examine acetate utilization, fatty acid uptake, and lipid droplet mobilization
6. Fatty acid synthase (FASN) inhibition causes cell death, but fatty acids cannot rescue the phenotype	Drug off-target effects, lipotoxicity, or non-lipid-synthesis mechanisms may be involved	Switch to another inhibition strategy and perform target validation

10. Experimental Workflow from Pathway Clues to Dependency Validation

A reliable experimental workflow for studying de novo fatty acid synthesis in cancer cells should begin with pathway clues and then progressively determine whether carbon sources enter fatty acids, whether key enzymes affect cellular phenotypes, and whether exogenous fatty acids can compensate for changes caused by pathway blockade.

Step	Experimental content	Purpose
1. Define baseline culture conditions	Record serum type, glucose concentration, glutamine concentration, oxygen conditions, and cell density	Avoid culture-condition differences affecting fatty acid synthesis flux and interpretation of cellular phenotypes
2. Screen pathway expression	Detect ATP citrate lyase, acetyl-CoA carboxylase 1, and fatty acid synthase	Determine whether there are expression-level clues indicating changes in the de novo fatty acid synthesis pathway
3. Detect changes in lipid composition	Analyze changes in palmitic acid, oleic acid, phospholipids, triglycerides, and related lipids	Determine whether cellular lipid composition has changed in a way related to fatty acid synthesis
4. Perform glucose carbon-source tracing	Use uniformly labeled ^13C-glucose	Determine whether glucose-derived carbon enters citrate and ultimately palmitic acid and complex lipids, indirectly assessing the acetyl-CoA source for lipid synthesis
5. Perform glutamine carbon-source tracing	Use uniformly labeled ^13C-glutamine	Determine whether carbon-source switching occurs under hypoxia, nutrient stress, or restricted mitochondrial function
6. Inhibit key pathway nodes	Target ATP citrate lyase, acetyl-CoA carboxylase 1, or fatty acid synthase	Determine whether blocking de novo fatty acid synthesis affects cell proliferation, colony formation, or survival
7. Perform exogenous fatty acid rescue	Supplement palmitic acid, oleic acid, or fatty acid mixtures, and include fatty acid-free bovine serum albumin controls	Determine whether changes in cellular phenotype are related to insufficient fatty acid supply
8. Compare key environmental conditions	Compare regular serum, lipid-depleted serum, hypoxia, two-dimensional culture, and three-dimensional models	Determine whether dependence on fatty acid synthesis is influenced by exogenous lipids, oxygen, and culture model
9. Recheck key conclusions	Combine genetic knockdown or knockout, different inhibitors, mass spectrometry-based flux analysis, and fatty acid rescue experiments	Reduce interpretive bias caused by a single detection method or a single drug

11. Product Navigation Table for Research on De Novo Fatty Acid Synthesis in Cancer Cells

Research or experimental goal	Recommended table to check first	Why start with this table	Recommended linked table	Navigation guidance
Determine whether cancer cells have de novo fatty acid synthesis flux	Table 1	Table 1 includes glucose, glutamine, ^13C-labeled glucose, ^13C-labeled glutamine, and ^13C-labeled sodium acetate, which can be used to trace whether carbon sources enter citrate, acetyl-CoA-related metabolic pools, palmitic acid, and complex lipids	Tables 3 and 4	First use labeled carbon sources to confirm de novo fatty acid synthesis flux, then use key enzyme inhibitors to determine whether decreased flux affects cell proliferation, survival, or lipid composition
Compare the contributions of glucose and glutamine to fatty acid synthesis	Table 1	Table 1 lists basic carbon sources and ^13C tracing substrates, supporting carbon-source analysis under normoxia, hypoxia, and mitochondrial stress	Table 3	First determine which nutrient source contributes most of the carbon in fatty acids, then use ATP citrate lyase or acetyl-CoA carboxylase inhibitors to validate key nodes through which carbon enters the fatty acid synthesis pathway
Study carbon-source switching under hypoxia, low nutrients, or mitochondrial stress	Table 1	^13C-labeled glucose, ^13C-labeled glutamine, and ^13C-labeled sodium acetate in Table 1 can be used to compare carbon flow under different conditions	Tables 3 and 2	Under hypoxia or mitochondrial stress, glutamine can participate in citrate and lipid precursor supply through reductive carboxylation, and acetate may also replenish the acetyl-CoA pool through acetyl-CoA synthetase short-chain family member 2 and related pathways; exogenous fatty acid supplementation can be linked when needed to determine whether lipid compensation occurs
Validate whether ATP citrate lyase controls the entry point of fatty acid synthesis	Table 3	Table 3 contains ATP citrate lyase inhibitors, which can be used to block the conversion of citrate into cytosolic acetyl-CoA	Tables 1 and 2	First use inhibitors to observe lipid synthesis and cellular phenotypes, then use ^13C tracing to confirm whether carbon flow decreases, and use exogenous fatty acid supplementation to determine whether the phenotype is related to insufficient fatty acid supply
Validate whether acetyl-CoA carboxylase-related nodes affect malonyl-CoA generation and fatty acid synthesis	Table 3	Table 3 contains several acetyl-CoA carboxylase inhibitors, which can be used to interfere with malonyl-CoA generation and determine whether substrate supply for fatty acid synthesis is limited	Tables 1 and 4	First evaluate whether the pathway is controlled at the acetyl-CoA carboxylase node, then combine with fatty acid synthase inhibitors to compare lipid composition and cellular phenotypes after blocking different nodes; when using acetyl-CoA carboxylase 1/2 inhibitors, note that fatty acid synthesis and fatty acid oxidation regulation may both be affected
Validate whether fatty acid synthase constitutes a functional dependency in cancer cells	Table 4	Table 4 lists fatty acid synthase inhibitors, which can be used to observe changes in cell proliferation, colony formation, cell death, and lipid composition after palmitic acid synthesis is blocked	Tables 2 and 1	After fatty acid synthase inhibition, fatty acid rescue and ^13C tracing should be linked to determine whether the cellular phenotype results from blockade of de novo fatty acid synthesis
Perform rescue experiments after inhibition of de novo fatty acid synthesis	Table 2	Table 2 includes palmitic acid, oleic acid, sodium palmitate, sodium oleate, and fatty acid-free bovine serum albumin, which can be used to establish exogenous fatty acid supplementation and carrier controls	Tables 4 and 3	First supplement exogenous fatty acids to observe whether the phenotype can be restored, then return to key enzyme inhibition experiments to determine whether the phenotype is related to insufficient fatty acid supply; palmitic acid and oleic acid rescue results should be interpreted together with concentration, albumin-complexing method, and lipotoxicity risk
Distinguish exogenous fatty acid uptake from cellular self-synthesis	Table 2	Table 2 includes ^13C-labeled palmitic acid and ^13C-labeled oleic acid, which can be used to trace the incorporation of exogenous fatty acids into complex lipids	Table 1	Comparing ^13C-labeled fatty acids with ^13C-labeled glucose and ^13C-labeled glutamine can distinguish the relative contributions of exogenous uptake and de novo synthesis
Evaluate whether serum lipids affect experimental conclusions	Table 2	Fatty acid-free bovine serum albumin and fatty acid supplementation reagents in Table 2 can be used to set lipid supplementation, lipid deprivation, and carrier control conditions	Tables 3 and 4	Regular serum may mask dependence on de novo fatty acid synthesis; combining exogenous fatty acid supplementation with inhibitor treatment can help determine whether cells depend on endogenous fatty acid synthesis
Establish a complete validation workflow for de novo fatty acid synthesis	Table 1	Table 1 first answers whether carbon sources enter the fatty acid synthesis pathway, which is the basis for subsequent evaluation of pathway dependency	Tables 3, 4, and 2	The workflow can follow the order of “carbon-source tracing—intervention at ATP citrate lyase or acetyl-CoA carboxylase nodes—fatty acid synthase blockade—exogenous fatty acid rescue,” forming an evidence chain from flux to functional dependency
Interpret whether cellular phenotypes after inhibitor treatment are related to lipid metabolism	Table 2	Table 2 provides fatty acid rescue and exogenous fatty acid tracing tools, which can be used to determine whether reduced cell viability is related to insufficient fatty acid supply	Tables 3 and 4	Reduced proliferation alone cannot directly prove dependence on de novo fatty acid synthesis; rescue experiments, flux detection, and different inhibition strategies are needed to exclude nonspecific effects
Prepare for in vitro enzymatic or metabolic assays of the fatty acid synthesis pathway	Table 1	Table 1 includes citric acid, acetyl-CoA sodium salt, malonyl-CoA lithium salt, and reduced coenzyme II, which can support key-node metabolite detection and reaction system construction	Tables 3 and 4	Suitable for establishing substrate, product, and inhibition-effect assays around ATP citrate lyase, acetyl-CoA carboxylase, and fatty acid synthase

Table 1 | Carbon Sources, Isotope Tracing Substrates, and Pathway Metabolites

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
Basic glucose carbon source	50-99-7	G640146	D-(+)-Glucose	Moligand™, animal-origin-free, low endotoxin, for cell culture, ≥99%	Used to establish basic carbon-source conditions for cell culture; can serve as an unlabeled control and be combined with ^13C-glucose tracing to determine whether glucose-derived carbon enters the fatty acid synthesis pathway
Basic glutamine carbon source	56-85-9	G640162	L-Glutamine	Moligand™, animal-origin-free, low endotoxin, for cell culture, ≥99%	Used to maintain cellular nitrogen supply and anaplerotic metabolism; can serve as an unlabeled control and support comparison of the contribution of glutamine to lipid synthesis under normoxia, hypoxia, or mitochondrial stress
Upstream metabolite of ATP citrate lyase	77-92-9	C434175	Citric acid	Anhydrous grade, PharmPure™, USP, JP, BP, European Pharmacopoeia (Ph. Eur.), powder	Used to understand the metabolic node by which citrate is converted into cytosolic acetyl-CoA; can be used for related metabolite detection, standard preparation, and pathway teaching demonstrations
Glucose carbon-source tracer	110187-42-3	D346444	D-Glucose-^13C₆	≥99 atom% ^13C, ≥98%	Used to trace the entry of glucose-derived carbon into citrate, acetyl-CoA, palmitic acid, and complex lipids, and to determine whether cancer cells have glucose-driven de novo fatty acid synthesis flux
Glutamine carbon-source tracer	184161-19-1	L471811	L-Glutamine-^13C₅	Moligand™, ≥98 atom% ^13C, ≥95%	Used to observe whether glutamine-derived carbon enters citrate and fatty acids; suitable for experiments involving hypoxia, restricted mitochondrial function, or carbon-source switching
Tracer for acetyl-CoA sources	56374-56-2	S335300	Sodium acetate-^13C₂	≥99 atom% ^13C	Used to evaluate whether acetate replenishes the acetyl-CoA pool through acetyl-CoA synthetase short-chain family member 2 (ACSS2) and related pathways; suitable for studying metabolic compensation under ATP citrate lyase inhibition, hypoxia, or lipid deprivation
Reducing-power cofactor for fatty acid synthesis	2646-71-1	N1510346	β-Nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt hydrate (β-NADPH tetrasodium salt hydrate)	≥99%	Provides reducing power for the fatty acid synthase-catalyzed process; can be used for in vitro enzyme activity assays and construction of fatty acid synthesis reaction systems
Acetyl-CoA-related standard	102029-73-2	A463299	Acetyl coenzyme A sodium salt	≥90%	Corresponds to the cytosolic acetyl-CoA node; can be used for enzymatic experiments, establishment of metabolic detection methods, and research related to products of ATP citrate lyase activity
Malonyl-CoA-related standard	108347-84-8	M463170	Malonyl coenzyme A lithium salt	≥90% (HPLC)	Corresponds to the product node of acetyl-CoA carboxylase; can be used to detect malonyl-CoA generation, substrate supply for fatty acid synthesis, and related enzymatic experiments

Table 2 | Exogenous Fatty Acid Supplementation, Rescue Experiments, and Uptake Tracing

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
Unsaturated fatty acid rescue reagent	112-80-1	O1520032	Oleic acid	Injection grade, ≥98%	Used for exogenous unsaturated fatty acid supplementation after fatty acid synthesis is inhibited; can be used to observe cell proliferation, lipid droplet formation, and alleviation of lipid stress
Unsaturated fatty acid salt-form supplementation reagent	143-19-1	S1520034	Sodium Oleate	Injection grade	Can be used for exogenous oleic acid supplementation and fatty acid rescue experiments; suitable for comparing the compensatory effect of unsaturated fatty acids in cells with blocked lipid synthesis
Saturated fatty acid rescue reagent	57-10-3	P753896	Palmitic acid	Stearic acid ≤0.5%	A fatty acid related to the major product of fatty acid synthase; can be used to validate whether the phenotype after pathway inhibition is related to insufficient palmitic acid supply
Saturated fatty acid salt-form supplementation reagent	408-35-5	S161420	Sodium Palmitate	≥97% (GC) (T)	Used for exogenous saturated fatty acid supplementation; can be combined with an albumin carrier to establish palmitic acid rescue conditions and observe cellular responses after fatty acid synthesis is blocked
Fatty acid carrier and carrier control	9048-46-8	B754985	Bovine Serum Albumin (BSA)	Sterile-filtered, for cell culture, low endotoxin, 10% in DPBS, fatty acid free	Used to prepare fatty acid–albumin complexes and set carrier controls, reducing nonspecific stimulation caused by free fatty acids; suitable for cell-based fatty acid supplementation and rescue experiments
Exogenous palmitic acid uptake tracer	56599-85-0	P474096	Palmitic acid-^13C₁₆	≥98 atom% ^13C, ≥98%	Used to trace uptake of exogenous palmitic acid and its incorporation into complex lipids such as phospholipids and triglycerides, distinguishing exogenous uptake from endogenous synthesis contributions
Exogenous oleic acid uptake tracer	287100-82-7	O465460	Oleic acid-^13C₁₈	≥98 atom% ^13C, ≥95%	Used to trace exogenous oleic acid uptake, lipid droplet storage, and complex lipid remodeling; suitable for fatty acid rescue and exogenous lipid compensation experiments

Table 3 | ATP Citrate Lyase and Acetyl-CoA Carboxylase Pathway Inhibitors

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
Acetyl-CoA carboxylase inhibitory tool compound	54857-86-2	T274911	TOFA (5-(tetradecyloxy)-2-furoic acid)	Moligand™, ≥99%	Used to inhibit acetyl-CoA carboxylase activity and reduce malonyl-CoA generation, allowing observation of how insufficient fatty acid chain-elongation substrate affects cancer cell lipid synthesis and proliferation phenotypes
Acetyl-CoA carboxylase 1/2 nonselective inhibitor	591778-68-6	C413618	CP 640186	Moligand™, ≥98%	Used to validate the effect of acetyl-CoA carboxylase activity on malonyl-CoA generation, fatty acid synthesis flux, and cell growth
Acetyl-CoA carboxylase 1/2 inhibitor	1301214-47-0	P288592	PF 05175157	≥98% (HPLC)	Used to simultaneously interfere with acetyl-CoA carboxylase 1 and 2, comparing changes in fatty acid synthesis, lipid composition, and cellular phenotypes after malonyl-CoA decreases
Acetyl-CoA carboxylase 1/2 allosteric inhibitor	1434639-57-2	N413991	ND646	≥98%	Used to validate acetyl-CoA carboxylase dependence; can be combined with ^13C-glucose or ^13C-glutamine tracing to determine whether fatty acid synthesis flux decreases
ATP citrate lyase inhibitor	154566-12-8	S286623	SB 204990	≥98% (HPLC)	Used to block the conversion of citrate into cytosolic acetyl-CoA and evaluate the dependence of cancer cell fatty acid synthesis on this carbon-entry point
ATP citrate lyase inhibitor	943962-47-8	B288525	BMS 303141	≥98%	Used to study decreased lipid synthesis, inhibited cell proliferation, and compensation by alternative sources such as acetate after cytosolic acetyl-CoA supply becomes limited

Table 4 | Fatty Acid Synthase Inhibitors and Fatty Acid Assembly Validation

Category	CAS No.	Aladdin Catalog No.	Name	Specification or Purity	Product Features and Applications
Fatty acid synthase-related inhibitor	96829-58-2	O159936	Orlistat	Moligand™, ≥97% (HPLC)	Can be used for pharmacological inhibition studies related to fatty acid synthase; gene knockdown and fatty acid rescue should also be combined to determine whether the phenotype results from blocked fatty acid synthesis
Human fatty acid synthase inhibitor	1332331-08-4	G288292	GSK 2194069	Moligand™, ≥97%	Used to observe changes in palmitic acid synthesis, complex lipid composition, cell proliferation, and colony formation after fatty acid synthase inhibition
Fatty acid synthase inhibitor	1533438-83-3	T413034	TVB-3166	≥99%	Used to validate the functional dependence of cancer cells on fatty acid synthase; can be combined with palmitic acid and oleic acid rescue experiments to determine whether fatty acid supplementation can restore the phenotype
Classic fatty acid synthase inhibitor	191282-48-1	C275352	C75 (racemic)	≥98%	Used as a classic control experiment for fatty acid synthesis inhibition; suitable for joint interpretation of cellular phenotypes together with flux analysis, lipidomics, and rescue experiments
Fatty acid synthase inhibitor	1399177-37-7	T414472	TVB-2640	≥98%	Used for pharmacological intervention in fatty acid synthase and cancer cell lipid metabolism research; can be used to evaluate the effects of pathway inhibition on cell growth, lipid remodeling, and combination-treatment responses
Natural product-type fatty acid synthase inhibitor	17397-89-6	C102399	Cerulenin	≥98%	Used to study metabolic and cellular phenotype changes after fatty acid chain assembly is blocked; can be combined with genetic validation to reduce interpretive bias from a single drug result

Note: The products listed above are representative Aladdin products. More product specifications can be searched on the Aladdin website using the product name, CAS number, or catalog number.

References

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[3] Hatzivassiliou G., Zhao F., Bauer D. E., et al. ATP citrate lyase inhibition can suppress tumor cell growth. Cancer Cell. 2005;8(4):311–321. doi:10.1016/j.ccr.2005.09.008.

[4] Metallo C. M., Gameiro P. A., Bell E. L., et al. Reductive glutamine metabolism by IDH1 mediates lipogenesis under hypoxia. Nature. 2012;481(7381):380–384. doi:10.1038/nature10602.

[5] Mullen A. R., Wheaton W. W., Jin E. S., et al. Reductive carboxylation supports growth in tumour cells with defective mitochondria. Nature. 2012;481(7381):385–388. doi:10.1038/nature10642.

[6] Koundouros N., Poulogiannis G. Reprogramming of fatty acid metabolism in cancer. British Journal of Cancer. 2020;122(1):4–22. doi:10.1038/s41416-019-0650-z.

[7] Yu Y., et al. Targeting acetyl-CoA carboxylase 1 for cancer therapy. Frontiers in Pharmacology. 2023;14:1129010. doi:10.3389/fphar.2023.1129010.

[8] Buglakova E., Ekelöf M., Schwaiger-Haber M., et al. Spatial single-cell isotope tracing reveals heterogeneity of de novo fatty acid synthesis in cancer. Nature Metabolism. 2024;6(9):1695–1711. doi:10.1038/s42255-024-01118-4.

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