A pair of amino acids commonly associated with high-protein diets may be helping prostate tumors acquire the fuel they need to grow, according to a study published in Nature Metabolism. Researchers led by Li, Liu and Jin report that isoleucine and valine—two branched-chain amino acids that the human body cannot produce and must obtain from food—can promote prostate cancer progression through a metabolic pathway centered on propionyl-CoA. The work identifies a previously underappreciated connection between amino-acid breakdown and cholesterol production, suggesting that nutrients entering a cancer cell through one biochemical route can be redirected into the construction of another. Rather than acting only as building blocks for proteins, isoleucine and valine appear to influence the tumor’s lipid economy. Their metabolism generates propionyl-CoA, a small but chemically active molecule that can alter how prostate cancer cells handle cholesterol, a lipid required for membrane formation, signaling and cellular proliferation.
The finding matters because prostate tumors are unusually dependent on cholesterol metabolism. Cholesterol is not simply a circulating substance associated with cardiovascular disease; inside a rapidly dividing cancer cell, it serves as a structural component of new membranes and as a precursor for steroid hormones. Prostate cancer cells can synthesize cholesterol internally, import it from the surrounding environment or store it in esterified form for later use. These processes are tightly controlled in healthy tissue, but malignant cells often reprogram them to sustain continuous growth. The new study places propionyl-CoA at an important point in that reprogramming. Produced when isoleucine and valine are broken down, propionyl-CoA normally enters pathways involved in energy production and carbon metabolism. In prostate cancer, however, the researchers’ findings indicate that it can influence the expression or activity of cholesterol-related machinery, effectively linking the availability of specific nutrients to the tumor’s capacity to manufacture and manage lipids.
This is a striking example of metabolic flexibility, the ability of cancer cells to change their preferred fuel sources as conditions shift. Tumors exist in environments where oxygen, glucose and other nutrients may fluctuate, so successful cancer cells frequently build alternative routes for obtaining energy and raw materials. Branched-chain amino acids are especially interesting because they are abundant in the diet and participate in several layers of metabolism. After uptake into cells, isoleucine and valine are converted through a series of enzymatic reactions that remove their amino groups and produce acyl-CoA intermediates. Among those intermediates is propionyl-CoA, which can be further processed through pathways connected to the tricarboxylic acid cycle. The study suggests that, in prostate cancer, propionyl-CoA is not merely burned for energy. Instead, it acts as a metabolic signal or substrate that helps push cholesterol metabolism toward a state favorable to tumor expansion.
The mechanism could help explain why nutrient availability sometimes has effects that are invisible when researchers examine only individual metabolites. A metabolite such as propionyl-CoA can influence cells in several ways at once. It may provide carbon for downstream reactions, alter the balance of competing metabolic pathways or affect protein regulation through chemical modifications. Propionyl-CoA is also related to propionylation, a form of lysine acylation that can modify proteins, including proteins associated with gene control. Such modifications have the potential to change the activity of transcriptional programs without altering the underlying DNA sequence. In the context of prostate cancer, this may help activate genes that support cholesterol synthesis, uptake, transport or storage. The paper’s central message is therefore broader than the effect of two amino acids: it reveals how a nutrient-derived CoA metabolite can connect carbon flow to the regulatory systems that determine whether a cancer cell accumulates the lipids needed for proliferation.
The cholesterol connection is particularly relevant to prostate biology because many prostate tumors remain responsive to androgen signaling, even after treatment. Androgens and other steroid hormones are synthesized from cholesterol-derived precursors, while cholesterol itself supports the organization of cell membranes and signaling platforms. Cancer cells can exploit this relationship by increasing cholesterol production or storage, strengthening pathways that maintain growth signals under therapeutic pressure. The study’s findings suggest that isoleucine and valine may reinforce this metabolic environment by increasing propionyl-CoA-dependent cholesterol activity. That does not mean that eating a single food immediately causes prostate cancer, nor does it establish that eliminating these amino acids from the diet would be safe or effective. Isoleucine and valine are essential nutrients involved in normal muscle maintenance, immune function and tissue repair. The significance lies in how malignant cells use them, not in treating the amino acids as inherently harmful.
The research also raises questions about the relationship between systemic nutrition and the tumor microenvironment. Blood concentrations of nutrients are influenced by diet, exercise, liver and muscle metabolism, kidney function and the overall state of health. Inside a tumor, however, nutrient concentrations can differ substantially from those in circulation. Cancer-associated fibroblasts, immune cells and blood vessels all contribute to the local chemical environment, and metabolites can move between these cell populations. If prostate cancer cells are particularly efficient at converting branched-chain amino acids into propionyl-CoA, they may gain a competitive advantage when those nutrients are available. Conversely, metabolic stress could force tumors to rely more heavily on alternative pathways. Mapping this exchange will be important, because the consequences of nutrient metabolism cannot be understood by studying cancer cells in isolation from the tissues around them.
From a therapeutic perspective, the pathway offers several possible intervention points. Researchers might investigate enzymes that break down isoleucine and valine, proteins that generate or consume propionyl-CoA, and the cholesterol-synthesis or cholesterol-transport systems influenced by the metabolite. Drugs that block cholesterol production already exist, and other treatments target androgen signaling or lipid storage. Combining such approaches with inhibitors of branched-chain amino-acid metabolism could, in principle, deprive prostate cancer cells of both the signal and the raw materials needed to maintain their cholesterol program. But the risks are substantial. The same metabolic enzymes operate in healthy organs, especially skeletal muscle, liver and heart, and broad inhibition could cause toxicity or interfere with normal energy balance. Any treatment strategy would therefore need to distinguish cancer-specific metabolic dependencies from the essential functions of these nutrients throughout the body.
The study points toward a future in which cancer metabolism is analyzed with far greater precision than the familiar labels of “sugar-burning” or “fat-burning.” A tumor may use glucose for one purpose, amino acids for another and lipids for a third, while constantly redirecting intermediates among these networks. In prostate cancer, the isoleucine–valine–propionyl-CoA axis may represent one of those hidden connections, allowing dietary nutrients to influence the production and handling of cholesterol. The next steps will be to determine how broadly this mechanism operates across prostate cancer subtypes, whether it changes during treatment or metastasis, and whether patients with distinct metabolic profiles respond differently to interventions aimed at it. For now, the work delivers a vivid biological warning against simplistic nutritional conclusions: the question is not merely what a cancer patient eats, but how a tumor rewires the chemistry of those nutrients to support its own survival.
Subject of Research: Isoleucine- and valine-driven metabolic regulation of cholesterol metabolism and prostate cancer progression
Article Title: Isoleucine and valine promote prostate cancer progression via propionyl-CoA-mediated cholesterol metabolism
Article References: Li, Z., Liu, S., Jin, W. et al. Isoleucine and valine promote prostate cancer progression via propionyl-CoA-mediated cholesterol metabolism. Nature Metabolism 8, 1772–1790 (2026). https://doi.org/10.1038/s42255-026-01583-z
Image Credits: AI Generated
DOI: 10.1038/s42255-026-01583-z
Keywords: prostate cancer, isoleucine, valine, branched-chain amino acids, propionyl-CoA, cholesterol metabolism, cancer metabolism, tumor progression, lipid metabolism, precision oncology
