Elevated ASCL2 expression in breast cancer is associated with the poor prognosis of patients.

Achaete scute-like 2 (ASCL2) is a member of the basic helix-loop-helix (bHLH) transcription factors, and is expressed mainly in intestinal stem cells under normal conditions. Recently, aberrantly elevated ASCL2 was detected in cancer tissues, but the clinical relevance of ASCL2 in breast cancers remains to be decided. In this study, we evaluated the expression of ASCL2 and its relationship to cancer progression in specimens from 191 cases of breast cancer patients with follow-up information. The results indicated that ASCL2 was highly expressed in cancer cells while it was undetectable in normal epithelial cells. Moreover, the expression of ASCL2 was positively correlated with breast tumor size, lymphatic metastasis and the active growth of tumor cells as shown by increased expression of Ki67. Kaplan-Meier analysis revealed that patients with higher levels of ASCL2 suffered higher tumor recurrent rate. Multivariable Cox-regression analysis showed that elevated expression of ASCL2 was an independent and unfavorable indicator of tumor relapse in breast cancer patients. Altogether, our study suggests that ASCL2 defines a subgroup of highly progressive breast cancer and serves as a marker to evaluate the risk of cancer relapse.