Increased HOXC6 expression predicts chemotherapy sensitivity in patients with esophageal squamous cell carcinoma

Increased expression of homeobox C6 (HOXC6) predicts poor prognosis of patients with esophageal squamous cell carcinoma (ESCC) and promotes ESCC cell proliferation. Additionally, the expression of HOXC6 was upregulated in chemosensitive ESCC cell lines. Therefore, it was hypothesized that HOXC6 may be associated with chemosensitivity of ESCC. Patients with ESCC who underwent neoadjuvant chemotherapy followed by surgery by a single-surgeon team between January 2000 and December 2012 were enrolled in the present study. Pretreatment biopsy specimens and postoperative resection samples were collected. Immunohistochemistry was performed to examine HOXC6 expression, and the association between HOXC6 expression and tumor regression grade (TRG) was analyzed. In cell lines exhibiting stable knockdown of HOXC6, Cell Counting Kit-8 assays were used to evaluate the chemosensitivity of cells to various concentrations of cisplatin and paclitaxel. A total of 51 pretreatment biopsy specimens were assessed, and patients with increased expression of HOXC6 in pretreatment biopsy specimens exhibited higher TRGs. A total of 186 surgical samples were evaluated; HOXC6 was expressed at a decreased level in patients with higher TRG and at a high level in patients with lower TRG. In addition, downregulation of HOXC6 decreased the sensitivity of ESCC cell lines to cisplatin and paclitaxel, resulting in an increased half-maximal inhibitory concentration. Increased expression of HOXC6 prior to treatment was associated with chemosensitivity in ESCC tissues.