Preclinical study finds PTPN12 restrains colorectal cancer immunity

In a preclinical study of colorectal cancer, researchers identified PTPN12 as a tumor-intrinsic barrier that suppresses double-stranded RNA sensing and the resulting interferon response. Inducible PTPN12 knockdown inhibited the growth of pre-established tumors and overcame resistance to immunotherapy in vivo, according to the report in Nature Communications. The experiments provide a mechanistic link between two processes that restrain antitumor immunity: epigenetic silencing of transposable elements and the cytoskeletal organization of cytosolic double-stranded RNA.

The researchers began with an in vivo clustered regularly interspaced short palindromic repeats screen to identify intrinsic regulators of double-stranded RNA sensing in microsatellite-stable colorectal cancer. This cancer subtype characteristically lacks the endogenous double-stranded RNA and interferon response that is crucial to the efficacy of immune checkpoint inhibition, leaving it refractory to immunotherapy. PTPN12 emerged from the screen as a physiological barrier that restrains this response. The study focused on tumor models and the molecular mechanism of resistance; it did not test PTPN12 suppression as a treatment in people with colorectal cancer.

TRIM28 was identified as a direct PTPN12 substrate. PTPN12 removes phosphorylation at tyrosine 370 on TRIM28, stabilizing repressive complexes that silence transposable elements. In parallel, PTPN12 rewires the adhesive cytoskeleton and disrupts the spatial organization of cytosolic double-stranded RNA required for efficient innate sensing. The findings therefore support a dual mechanism: PTPN12 restrains both an epigenetic program that limits expression of endogenous RNA and a cytoskeletal program that influences where that RNA is positioned for immune detection. TRIM28-dependent silencing and cytoskeletal remodeling are presented as coordinated components of the same tumor-intrinsic barrier.

Pharmacologically induced PTPN12 knockdown reproduced the massive accumulation of double-stranded RNA observed after PTPN12 ablation. In tumor models, this intervention inhibited the growth of tumors that had already formed and overcame resistance to immunotherapy in vivo. The result connects the molecular findings with a functional antitumor effect, but the evidence remains preclinical. The authors propose that targeting PTPN12 may offer a way to augment antitumor immunity and overcome immunotherapy resistance in microsatellite-stable colorectal cancer, although the study does not establish clinical safety or efficacy in patients.

Subject of Research: Tumor-intrinsic control of double-stranded RNA sensing and immunotherapy resistance in colorectal cancer models

Article Title: Tumor-intrinsic PTPN12 suppresses anti-tumor immunity in colorectal cancer by restraining a dual epigenetic and cytoskeletal dsRNA sensing program

Article References: Huo, Y., Tian, Y., Wang, D., Ping, Y., Zhang, C., Li, Y., Li, M., Duan, Y., Wang, Y., Feng, S., Zhao, Q., Guo, K., Xu, Y., Wang, B., Li, Z., Zhang, B., & Zhang, Y. (2026). Tumor-intrinsic PTPN12 suppresses anti-tumor immunity in colorectal cancer by restraining a dual epigenetic and cytoskeletal dsRNA sensing program. Nature Communications. https://doi.org/10.1038/s41467-026-78487-9

Image Credits: AI Generated

DOI: 10.1038/s41467-026-78487-9

Keywords: PTPN12, colorectal cancer, microsatellite-stable cancer, double-stranded RNA, immune checkpoint therapy, TRIM28, interferon response, epigenetic silencing, cytoskeleton, tumor immunity, Tumor-intrinsic, suppresses