Aim: In the present study, we sought to explore potential differences in the expression and promoter methylation of mitogen-activated protein kinase 1 (MAPK1) between tumor and marginal cells of breast cancer lesions.
Methods: A total of 50 randomly selected patients with breast cancer (BCa) undergoing needle biopsy were enrolled. Clinical specimens containing both tumor and marginal cells were collected and preserved. After DNA extraction using specific primers, MAPK1 mRNA and promoter methylation were measured with spectrophotometry at 260/280 nm absorption wavelengths. To deliver a comparative analysis, data from The Cancer Genome Atlas (TCGA) program regarding breast cancer (BRCA), were downloaded from Xena Functional Genomics Explorer and separately analyzed. The suitability of MAPK1 expression and promoter methylation as biomarkers for BCa was analyzed with receiver operating characteristic (ROC) curves.
Results: We found a positive correlation between tumor stage and MAPK1 expression (P-value: 0.029) in BCa. Likewise, MAPK1 expression was significantly associated with lymph node metastasis (P-value: 0.018). There was a significant difference in the expression of MAPK1 mRNA between tumor and marginal cells of BCa and BRCA (P-value < 0.001). However, we did not find any statistically significant difference in MAPK1 promoter methylation between tumor and marginal cells of both BCa and BRCA. With an area under the curve (AUC) of 0.71, the diagnostic accuracy of MAPK1 expression in BCa and BRCA was validated. However, MAPK1 promoter methylation was not found to be a suitable biomarker.
Conclusion: Our findings suggest that while MAPK1 expression, might be a promising biomarker for evaluating oncogenic activity in patients suspected of BCa. We were not able to detect a prognostic/diagnostic role for MAPK1 promoter methylation.
Keywords: Breast cancer; ERK2; MAPK1; mitogen-activated protein kinase 1; promoter methylation.