Elucidation of the role of Per-Arnt-Sim Kinase in the molecular pathogenesis of cancer in breast cancer cell lines

Introduction: Breast cancer remains a major public health challenge due to its high molecular heterogeneity, metastatic potential, and therapy resistance, particularly in Triple-Negative Breast Cancer (TNBC). Per-Arnt-Sim Kinase (PASK), a cellular energy-sensing kinase, has been implicated in proliferation, metabolic reprogramming, and metastatic progression. This study aimed to investigate the oncogenic role and therapeutic target potential of PASK in breast cancer pathogenesis. Materials and Methods: MDA-MB-231, MDA-MB-436, BT474, MCF-7, and MCF10A cells were used in this study. PASK expression was suppressed using siRNA-mediated gene silencing and selective PASK inhibitors. Cell viability, proliferation, colony formation, apoptosis, mitochondrial membrane potential, and cell cycle alterations were evaluated using MTT assay, colony formation assay, Annexin V/PI, Caspase-3/7, JC-1 flow cytometry, and Western blot analyses. In addition, bioinformatic analyses were performed to determine the prognostic significance of PASK expression. Results: Following PASK siRNA application, cell viability decreased to 42.67% ± 1.53% in MDA-MB 231 cells and 49.00% ± 1.00% in MCF7 cells (p < 0.0001), while colony formation capacity dropped to 14.67% ± 2.52% and the apoptotic cell rate increased to 26.00% ± 1.00% (p < 0.001). PASK inhibition triggered mitochondrial dysfunction, increasing the population with low mitochondrial membrane potential to 30.67% ± 0.58% in MDA-MB 231 cells (p < 0.0001). At the molecular level, Cyclin D1 expression decreased to 10.33% ± 3.51%, Bcl-2 levels declined to 21.00% ± 1.00% . In dose-dependent analyses, the 25 nmol PASK 10 siRNA dose emerged as the most effective inhibitory strategy, reducing SRC and P-SRC expression to 30.67% ± 3.06% and 25.67% ± 6.03%, respectively. These findings confirm that PASK acts as a central oncogenic regulator managing proliferation, apoptosis resistance, and metastasis in breast cancer. Conclusion: These findings indicate that PASK functions as a central regulator of proliferation, apoptosis evasion, and metastatic progression in breast cancer. PASK may serve as both a prognostic biomarker and a promising therapeutic target for the development of novel targeted therapies, particularly in aggressive breast cancer subtypes. Keywords: Apoptosis, Breast Cancer, EMT, Oncogenic Signaling, PASK, siRNA