Understanding the factors that hamper immune therapy in breast cancer may increase the range of patients who benefit. Here authors show that breast cancer cells produce and subsequently transfer... Show moreUnderstanding the factors that hamper immune therapy in breast cancer may increase the range of patients who benefit. Here authors show that breast cancer cells produce and subsequently transfer active TGF-beta type II receptors to CD8 + T cells to render them exhausted, thus paralyzing the anti-tumor immune response.Cancer immunotherapies have shown clinical success in various types of tumors but the patient response rate is low, particularly in breast cancer. Here we report that malignant breast cancer cells can transfer active TGF-beta type II receptor (T beta RII) via tumor-derived extracellular vesicles (TEV) and thereby stimulate TGF-beta signaling in recipient cells. Up-take of extracellular vesicle-T beta RII (EV-T beta RII) in low-grade tumor cells initiates epithelial-to-mesenchymal transition (EMT), thus reinforcing cancer stemness and increasing metastasis in intracardial xenograft and orthotopic transplantation models. EV-T beta RII delivered as cargo to CD8(+) T cells induces the activation of SMAD3 which we demonstrated to associate and cooperate with TCF1 transcription factor to impose CD8(+) T cell exhaustion, resulting in failure of immunotherapy. The levels of T beta RII+ circulating extracellular vesicles (crEV) appears to correlate with tumor burden, metastasis and patient survival, thereby serve as a non-invasive screening tool to detect malignant breast tumor stages. Thus, our findings not only identify a possible mechanism by which breast cancer cells can promote T cell exhaustion and dampen host anti-tumor immunity, but may also identify a target for immune therapy against the most devastating breast tumors. Show less
Xie, F.; Zhou, X.X.; Li, H.Y.; Su, P.; Liu, S.J.; Li, R.; ... ; Zhang, L. 2022
TGF-beta signaling is a key player in tumor progression and immune evasion, and is associated with poor response to cancer immunotherapies. Here, we identified ubiquitin-specific peptidase 8 (USP8)... Show moreTGF-beta signaling is a key player in tumor progression and immune evasion, and is associated with poor response to cancer immunotherapies. Here, we identified ubiquitin-specific peptidase 8 (USP8) as a metastasis enhancer and a highly active deubiquitinase in aggressive breast tumors. USP8 acts both as a cancer stemness-promoting factor and an activator of the TGF-beta/SMAD signaling pathway. USP8 directly deubiquitinates and stabilizes the type II TGF-beta receptor T beta RII, leading to its increased expression in the plasma membrane and in tumor-derived extracellular vesicles (TEVs). Increased USP8 activity was observed in patients resistant to neoadjuvant chemotherapies. USP8 promotes TGF-beta/SMAD-induced epithelial-mesenchymal transition (EMT), invasion, and metastasis in tumor cells. USP8 expression also enables T beta RII+ circulating extracellular vesicles (crEVs) to induce T cell exhaustion and chemoimmunotherapy resistance. Pharmacological inhibition of USP8 antagonizes TGF-beta/SMAD signaling, and reduces T beta RII stability and the number of T beta RII+ crEVs to prevent CD8+ T cell exhaustion and to reactivate anti-tumor immunity. Our findings not only reveal a novel mechanism whereby USP8 regulates the cancer microenvironment but also demonstrate the therapeutic advantages of engineering USP8 inhibitors to simultaneously suppress metastasis and improve the efficacy of cancer immunotherapy. Show less
