Correlation of expression of Akt1 and E2F1 and their phosphorylated forms in breast cancer patients with clinicopathological parameters.

Breast cancer is the leading cancer worldwide among women. Traditional clinicopathological prognostic and predictive markers need refining to improve clinical outcomes. This study explored the association between traditional clinicopathological factors and the expression of Akt1 and E2F1 transduction proteins and their phosphorylated forms in breast cancer, to determine their value as novel biomarkers and potential therapeutic targets. Tumor tissues from 94 female breast cancer patients were examined for immunophenotypic expression of total Akt1, pAkt1 (Serine 473), pAkt1 (Threonine 308), total E2F1, pE2F1 (Thr433) and pE2F1 (Ser337). The expression of pAkt1 (Ser473) was significantly associated with ER/PR positive status and total E2F1 with older age (> 50), lymph node involvement and HER2 positivity. There was a significant association between triple negative cancers and total and pAkt1 (Thr308). pAkt1 (Ser473) showed an inverse relationship with Luminal B cancers and pE2F1 (Thr433) showed an inverse association with triple negative cancers. Higher expression of pE2F1 (Ser337) was associated with better OS. Both pAkt1 (Ser473 and Thr308) proteins showed significant association with poorer patient outcomes. E2F1 (Ser337) showed a significant positive correlation with response to chemotherapy. The study suggests that a pAkt1-/pE2F1+ phenotype could indicate an opportunity to minimize chemotherapeutic options in older women; conversely a pAkt1+/pE2F1- phenotype could prompt a more aggressive regimen. Further exploration of this phenotype in younger women with breast cancer and triple-negative breast cancers is warranted.

Calpain-1 Expression in Triple-Negative Breast Cancer: A Potential Prognostic Factor Independent of the Proliferative/Apoptotic Index.

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer in which calpain system plays an important role in its cellular processes including apoptosis and proliferation. Although such roles have been assessed in tumor pathogenesis, the correlation of its expression to the proliferating/apoptotic index has not been studied yet. Immunohistochemical staining of calpain-1 was performed on paraffin-embedded tissues to correlate its expression with clinicopathological variables and outcome. The proliferation activity was determined by calculating the percentage of cells expressing the Ki-67 antigen. The apoptotic index was assessed morphologically and biochemically using Haematoxylin & Eosin method and Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, respectively. Calpain-1 was significantly expressed in TNBC tissues varying from low to high with a significant correlation to lymph node status but not with the other clinicopathological variables, suggesting its role as a prognostic factor. In addition, a positive correlation was found between both apoptotic counts assays (P < 0.001, r = 0.547) as well as with proliferation (P = 0.045). Calpain-1 expression had no significant correlation with either proliferation (P = 0.29) or apoptotic indices (P = 0.071 and P = 0.100). Determining calpain-1 expression may provide relevant prognostic value for TNBC cancer patients.

Cisplatin Induces Apoptosis Through the Endoplasmic Reticulum-mediated, Calpain 1 Pathway in Triple-negative Breast Cancer Cells.

BACKGROUND: Breast cancer is the most common cancer in women worldwide. Triple-negative breast cancer (TNBC) is an aggressive type that can be treated using platinum-based chemotherapy such as cisplatin (cis-diamminedichloroplatinum II). Although the calpain protein is essential in many cellular processes, including apoptosis, cell signaling, and proliferation, its role in cisplatin-induced apoptosis in TNBC cells is not fully understood. The present study assessed calpain 1-dependent, cisplatin-induced apoptosis in TNBC cells. MATERIALS AND METHODS: MDA-MB231 cells were treated with different concentrations of cisplatin (0, 20, and 40 µM). The cisplatin deposit and its effect on endoplasmic reticulum and, subsequently, calcium release were detected using transmission electron microscopy and Von Koss staining, respectively. Calpain 1 messenger RNA, protein content, and apoptosis was measured using reverse transcriptase-polymerase chain reaction, Western blotting, and Hoechst stain, respectively. In addition, calpain modulation, by either activation or inhibition, and its effect on cisplatin-induced apoptosis were assessed. RESULTS: Our results showed that cisplatin induced endoplasmic reticulum stress, indicated by an increase in calcium staining and protein expression of glucose-regulated protein 78 and calmodulin, followed by cleavage of α-fodrin and caspase-12 and, eventually, apoptosis. Cyclopiazonic acid showed a similar effect and enhanced the sensitivity of these cells to cisplatin treatment. In contrast, calpain 1 inhibition by both specific small interfering RNA and exogenous inhibitor (calpeptin) attenuated cisplatin-induced apoptosis in these cells. CONCLUSION: Altogether, these findings suggest, for the first time, that calpain 1 activation by endoplasmic reticulum plays an essential role in sensitizing TNBC cells to cisplatin-induced apoptosis. This finding will allow exploration of new insights for the treatment of TNBC by overcoming its resistance to apoptosis.