Elevated expression of phosphorylated c-Jun NH2-terminal kinase in basal-like and “triple-negative” breast cancers

Basal-like carcinomas and human epidermal growth factor receptor 2 (HER-2/neu) overexpression carcinomas are the subgroups of breast cancers that have the most aggressive clinical behavior. Phosphorylation/activation of c-Jun NH2-terminal kinase is characterized as a stress-activated protein kinase, which regulates apoptosis after cellular stress. The aim of this study was to evaluate the association of phosphorylated c-Jun NH2-terminal kinase expression with phenotypes and clinicopathologic parameters of breast cancer. Phosphorylated c-Jun NH2-terminal kinase was immunohistochemically measured in a cohort of 160 patients with invasive breast cancer treated with therapeutic surgery followed by anthracycline or docetaxel-based chemotherapy. These results were further correlated with the phenotypes and clinicopathologic characteristics of breast cancers. Increased phosphorylated c-Jun NH2-terminal kinase expression was significantly associated with lack of estrogen receptor expression (P < .0001), positivity for cytokeratins 5/6 (P = .029), epidermal growth factor receptor (P = .035), basal-like phenotype (P = .015), and “triple-negative” phenotype (P = .01). Furthermore, the positive expression of phosphorylated c-Jun NH2-terminal kinase was positively correlated with p-glycoprotein (r = 0.54, P < .0001) and multidrug resistance–associated protein 1(r = 0.38, P < .0001) but not with lung resistance protein (r = −0.02, P = .78). Our results indicate that the activation of phosphorylated c-Jun NH2-terminal kinase may play a role in the carcinogenesis of basal-like and triple-negative breast carcinoma.