A single RNA molecule can flip prostate cancer from treatable to drug-resistant — and back

A single molecule — one of the smallest and most overlooked in human biology — can determine whether a prostate tumor responds to treatment or evolves into an aggressive, drug-resistant form. And crucially, researchers have shown they can use that same molecule to reverse the process.

Published October 7, 2026, in Nature, the study from Fred Hutchinson Cancer Center in Seattle and the University of Chicago identifies a specific transfer RNA, called tRNA1Arg(UCU), as a molecular switch controlling prostate cancer cell identity. When levels of this tRNA fall, tumors shed their dependence on androgen receptor signaling — the pathway that standard therapies target — and shift into a more aggressive, treatment-resistant state. When researchers restored the tRNA in resistant tumor models, the cells reverted to a drug-sensitive state.

The discovery opens an entirely new realm of cancer biology that was previously unrecognized. Historically, tRNAs have been thought to play a bystander role in cell maintenance and disease, but our study shows that tRNAs can actively shape the identity of cancer cells.— Andrew Hsieh, MD, professor and associate director of Fred Hutch's Human Biology Division, co-corresponding author

Prostate cancer is the second-leading cause of cancer death among men in the United States. Most tumors initially depend on androgen receptor signaling for growth, making them vulnerable to androgen deprivation therapies and drugs like enzalutamide, apalutamide, and darolutamide. Over time, some tumors undergo what researchers call lineage plasticity — cancer cells lose their dependence on androgen signaling and acquire features of neuroendocrine prostate cancer, a form that resists virtually all standard therapies. Current options for that resistant form are largely limited to platinum-based chemotherapies, which offer modest survival benefits.

The molecular mechanics driving that transformation have remained poorly understood. First author Yeon Soo Kim, PhD, a Fred Hutch postdoctoral researcher, set out to examine the role of protein synthesis — specifically the step where tRNA ferries amino acids to build proteins — in the disease's progression. Working across prostate cancer cell lines, mouse models, and patient tumor samples, Kim and her coauthors found a consistent pattern: tRNA1Arg(UCU) was abundant in androgen receptor-dependent, treatment-sensitive tumors and diminished in treatment-resistant ones.

We found that we can shift the cell state between androgen receptor-dependent to an androgen receptor-independent state with a single tRNA. This is important because changes in cell identity are a major reason prostate cancers become resistant to treatment.— Yeon Soo Kim, PhD, first author, Fred Hutch postdoctoral researcher

The team then traced the pathway to understand how the switch works. When tRNA1Arg(UCU) levels drop, so do levels of a protein called SMARCC2, which helps organize DNA and keeps prostate cancer cells in a treatment-sensitive state. The loss of SMARCC2 disrupts normal cell identity, making it easier for cancer cells to transition into the aggressive, therapy-resistant form. Two proteins — TARDBP and ZSCAN29 — were identified as regulators that help keep the tRNA active. Reducing tRNA1Arg(UCU) in prostate cancer cells also quickly lowered androgen receptor levels, the very target that most prostate cancer drugs are designed to block.

For a long time, tRNAs were considered basic housekeeping units, serving as static transfer vehicles of translating the genetic code during protein synthesis. In reality, tRNA levels are dynamically tuned to control cell fate, and the low levels of tRNAArg (UCU)-1 act as a molecular switch that allows prostate cancer cells to escape from the treatment and become a more aggressive type of cancer.— Tao Pan, PhD, Professor of Biochemistry and Molecular Biology at UChicago, co-lead author

The most consequential finding may be what happens when the switch is flipped back. Restoring tRNA1Arg(UCU) — or the downstream protein SMARCC2 — successfully rescued androgen receptor activity and made resistant cells responsive to treatment again in the experimental models. That reversibility distinguishes this mechanism from the DNA mutations that drive many other forms of drug resistance.

Unlike DNA mutations where changes are permanent, RNA regulated processes are reversible. It opens up an unexplored therapeutic landscape focused on modulating RNA dosage and tRNA to overcome drug resistance.— Tao Pan, PhD, Professor of Biochemistry and Molecular Biology at UChicago, co-lead author

The researchers suggest that RNA-targeted therapeutics — such as synthetic tRNA mimics or small molecules that boost tRNA1Arg(UCU) production — could re-sensitize hard-to-treat tumors to existing androgen receptor-targeted drugs that are already widely available. Kim and Hsieh are also exploring whether the tRNA could serve as a biomarker to guide more precise treatment decisions.

The implications may extend well beyond prostate cancer. Because the study used prostate cancer as a model for tRNA-dependent cell state changes, the researchers believe the approach could apply to other cancers that undergo identity switches after treatment — including lung and breast cancers, according to fredhutch.org.

In this study we used prostate cancer as an archetype to study tRNA dependent state changes, but we think it's just the beginning. We can apply this approach to any type of disease models or other types of cancers that undergo identity switches after treatment, such as lung and breast cancers.— Yeon Soo Kim, PhD, first author, Fred Hutch postdoctoral researcher

The study was supported by the National Institutes of Health, the U.S. Department of Defense Prostate Cancer Research Program, the Prostate Cancer Foundation, the American Cancer Society, and the Pacific Northwest Prostate Cancer SPORE, among other funders. Co-corresponding author Tao Pan is also co-founder of MesoRNA, a UChicago spinout developing sequencing technologies for small non-coding RNA.

Why it matters — If tRNA levels can be pharmacologically restored in patients, tumors that have become resistant to widely available prostate cancer drugs could potentially be made sensitive to them again — a reversal that existing DNA-mutation-based resistance mechanisms do not allow.

Reported by fredhutch.org, biologicalsciences.uchicago.edu