Integrin α6β4 Upregulates PTPRZ1 Through UCHL1-Mediated Hif-1α Nuclear Accumulation to Promote Triple-Negative Breast Cancer Cell Invasive Properties.

Simple Summary: Integrin α6β4 makes triple-negative breast cancer (TNBC) more aggressive by controlling genes that drive tumor invasion and metastasis. PTPRZ1 is linked to cancer relapse, but its role in TNBC is not well understood. We discovered that PTPRZ1 expression is significantly increased by integrin α6β4 in TNBC. We also found that integrin β4 gene expression correlates with PTPRZ1 in breast cancer patient samples. Importantly, we found that integrin α6β4 controls PTPRZ1 through UCHL1, which in turn stabilized Hif-1α. When UCHL1 or PTPRZ1 are blocked, the aggressiveness driven by integrin β4 signaling decreased substantially. Data analysis showed that high levels of these genes (ITGB4, UCHL1, Hif1α, PTPRZ1) are linked to worse survival rates, especially in patients who received chemotherapy treatment. Our findings suggest that integrin α6β4 helps TNBC become invasive through UCHL1-Hif-1α regulation of PTPRZ1, pointing to a new approach to targeting integrin α6β4 signaling using PTPRZ1 and UCHL1 inhibitors. Integrin α6β4 drives triple-negative breast cancer (TNBC) aggressiveness through the transcriptional regulation of key genes. Here, we investigated how integrin α6β4 regulates protein tyrosine phosphatase receptor type Z1 (PTPRZ1). Using stable re-expression of integrin β4 (ITGB4) in cells naturally devoid of integrin α6β4 or knockdown or knockout (KO) of ITGB4, we found that integrin α6β4 regulates PTPRZ1 expression. To gain mechanistic insight, we focused on Hif-1α due to the impact of integrin α6β4 on a hypoxia-associated signature. We found that nuclear localization of Hif-1α, but not Hif-2α, was substantially enhanced with integrin α6β4 signaling. Hif-1α knockdown by shRNA or chemical inhibition decreased PTPRZ1 expression, while chemical activation of Hif-1α increased it. Upstream of Hif-1α, integrin α6β4 upregulates UCHL1 to stabilize Hif-1α and ultimately regulate PTPRZ1. Inhibition of UCHL1 and PTPRZ1 dramatically decreases integrin α6β4-mediated cell migration and three-dimensional invasive growth. Finally, public breast cancer database analyses demonstrated that ITGB4 correlates with PTPRZ1 and that high expression of ITGB4, UCHL1, HIF1A, and PTPRZ1 associated with decreased overall survival, distant metastasis free survival, post progression survival, and relapse-free survival. In summary, these findings provide a novel function of integrin α6β4 in promoting tumor invasive phenotypes through UCHL1-Hif-1α-mediated regulation of PTPRZ1. [ABSTRACT FROM AUTHOR]