DNA Methyltransferases 1-Regulated Methylation of Protein Kinase C Zeta Influences Its Expression in Breast Cancer Cells.

PURPOSE: Breast cancer (BC) is a predominant malignancy globally, surpassing lung cancer in terms of diagnostic frequency, with an escalating incidence rate in recent decades. Recent studies have investigated the role of protein kinase C zeta (PRKCZ) in diverse cellular processes in cancer biology. In this study, we evaluated the association between PRKCZ and deleterious outcomes in BC and elucidated the mechanisms underlying its expression in breast carcinoma. METHODS: The correlation between PRKCZ and survival rates of patients with BC was investigated using The Cancer Genome Atlas database. The methylation status of the PRKCZ promoter was analyzed using the UALCAN database. Furthermore, we investigated the mechanisms underlying PRKCZ inactivation in BC by treatment with transferase inhibitors, methylation-specific polymerase chain reaction (PCR) analysis, western blotting, and luciferase reporter gene assays. The degree of methylation and expression levels of PRKCZ, as regulated by DNA methyltransferase 1 (DNMT1), were quantified using quantitative PCR and western blotting. RESULTS: Our analysis revealed that decreased expression of PRKCZ in BC was significantly correlated with poor clinical prognosis. Furthermore, we observed that hypermethylation of the PRKCZ promoter contributed to its reduced expression in BC. Notably, DNMT1 has been identified as a critical regulator of PRKCZ methylation. CONCLUSION: Our findings elucidate the tumor-suppressive function of PRKCZ and provide insights into the molecular mechanisms underlying its downregulation in BC.