The PI3K/AKT/mTOR pathway sits at the heart of cellular growth control. When functioning normally, it relays signals from growth factor receptors on the cell surface to internal machinery that drives metabolism, protein synthesis, and proliferation. In many cancers, this circuit becomes permanently switched on, fueling uncontrolled division and survival. Pharmaceutical companies have developed a series of PI3K inhibitors to shut down this pathway, but clinical experience has repeatedly shown that tumors often possess intrinsic resistance mechanisms that blunt the drugs’ effectiveness from the very first dose. Understanding these mechanisms has become a priority for oncology research.

Compound 8 emerged from the team’s medicinal chemistry efforts as a novel fluorinated derivative of isoflavone, a class of natural plant compounds. In laboratory tests, the molecule showed robust anti-tumor activity against triple-negative breast cancer cells that express low levels of the androgen receptor, specifically the MDA-MB-231 cell line. However, when the researchers tested it against MDA-MB-453 cells, a triple-negative breast cancer line belonging to the luminal androgen receptor subtype that overexpresses the androgen receptor, the compound’s potency dropped dramatically. This disparity provided the investigators with a natural experiment: two cancer cell types, one vulnerable and one resistant, differing primarily in their androgen receptor abundance.

The androgen receptor, best known for its role in prostate cancer, is a nuclear transcription factor that binds testosterone and other androgens before migrating to DNA to activate specific gene programs. The luminal androgen receptor subtype of triple-negative breast cancer is characterized by high levels of this receptor, which has made anti-androgen therapy an attractive therapeutic concept for these tumors. The new study reveals that the receptor does far more than simply mark a tumor subtype. It actively orchestrates resistance to PI3K inhibition by blocking two of the key processes that compound 8 relies upon to kill cancer cells: autophagy-associated cell death and cell cycle arrest.

Autophagy is a cellular recycling system in which the cell digests its own components to survive stress. In cancer therapy, excessive or dysregulated autophagy can tip over into a form of programmed cell death, and many anti-cancer drugs work partly by pushing cells across this threshold. Using transcriptomic analysis, the researchers discovered that high androgen receptor abundance upregulates a gene called UBE2C, which encodes an enzyme involved in tagging proteins for destruction during cell division. Elevated UBE2C levels performed a double duty that protected resistant cells. First, UBE2C sustained mitotic progression, allowing cancer cells to keep dividing even under drug pressure. Second, and perhaps more surprisingly, UBE2C maintained autophagy in an inhibited state, preventing compound 8 from unleashing the autophagy-associated cytotoxicity that would normally kill the cells.

To confirm that this mechanism was not an artifact of a single cell line, the team validated their findings in prostate cancer models. They used LNCaP cells, which express high levels of the androgen receptor, and PC-3 cells, which express low levels. The same pattern emerged: androgen receptor-high cells resisted compound 8, while androgen receptor-low cells remained sensitive. This consistency across two hormonally distinct cancer types suggests that the AR-UBE2C-PI3K resistance axis is a conserved feature rather than a peculiarity of breast cancer biology, broadening the potential clinical relevance of the discovery considerably.

The therapeutic implications became clear when the researchers combined compound 8 with strategies to suppress the androgen receptor. Genetic silencing of the receptor, or pharmacological inhibition using enzalutamide, a clinically approved anti-androgen drug, sensitized the resistant cells to compound 8. The combination restored the drug’s ability to induce cell cycle arrest and promoted the autophagy-associated cytotoxicity that the androgen receptor had been suppressing. In effect, blocking the androgen receptor removed the molecular brake that UBE2C had placed on the cancer cells’ self-destruction program, allowing the PI3K inhibitor to work as intended.

The team then moved from cell culture to living organisms. In mouse models of cancer, the combination therapy synergistically suppressed tumor growth and metastasis, outperforming either agent alone. All animal experiments were conducted under the approval of the Institutional Animal Care and Use Committee at West China Hospital, Sichuan University. These in vivo results provide compelling preclinical evidence that the drug combination strategy could translate into a meaningful clinical approach for patients whose tumors overexpress the androgen receptor.

The study was supported by funding from the National Natural Science Foundation of China, the Fundamental Research Funds for the Central Universities, the China Postdoctoral Science Foundation, the Natural Science Foundation of Sichuan Province, and several institutional programs. The corresponding authors are Wei Liu, Lan Zhang, and Xiaojun Man, whose teams brought together expertise in biomimetic drug synthesis, cancer biotherapy, and urology. The article is published open access under a Creative Commons Attribution 4.0 license, making the full dataset and methods available to researchers worldwide.

For patients with androgen receptor-overexpressing breast or prostate cancers, the findings offer a molecular explanation for why PI3K inhibitors have sometimes fallen short and a concrete rationale for combining them with anti-androgen therapy. Rather than abandoning a promising drug class in the face of resistance, oncologists may soon be able to disarm the resistance mechanism directly, converting a futile single-agent approach into a synergistic two-pronged attack. As clinical trials test this combination strategy, the AR-UBE2C axis may become a biomarker that identifies which patients stand to benefit most from this newly illuminated therapeutic partnership.

Subject of Research: Targeting the AR-UBE2C axis unleashes autophagy-associated cell death to overcome intrinsic resistance to PI3K Inhibition in AR-overexpressed breast and prostate cancers

Article Title: Targeting the AR-UBE2C axis unleashes autophagy-associated cell death to overcome intrinsic resistance to PI3K Inhibition in AR-overexpressed breast and prostate cancers

Article References: Fu, L., Li, H., Li, Z., Liu, W., Zhang, L., & Man, X. (2026). Targeting the AR-UBE2C axis unleashes autophagy-associated cell death to overcome intrinsic resistance to PI3K Inhibition in AR-overexpressed breast and prostate cancers. Cell Death Discovery. https://doi.org/10.1038/s41420-026-03389-0

Image Credits: AI Generated

DOI: 10.1038/s41420-026-03389-0

Keywords: Targeting, AR-UBE2C, axis, unleashes, autophagy-associated, cell, death, overcome, intrinsic, resistance, PI3K, Inhibition