Overexpression of OTX1 promotes tumorigenesis in patients with esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a multifactorial disease and the sixth leading cause of death from cancer worldwide. Patients with ESCC usually have a short survival period due to the late stage at diagnosis. Incidence rates of ESCC remain high among the elderly. With recent advances, it has been demonstrated that ESCC tumors display a unique genetic profile. This study aimed to examine the possible function of OTX1 in ESCC. We collected paraffin-embedded tumor tissues from 107 patients originally diagnosed with ESCC at Xijing Hospital and fresh-harvested and paired adjacent normal esophageal tissues from 15 ESCC patients undergoing curative resection. The expression level of OTX1 was evaluated through immunohistochemistry and western blot. Prognostic and survival analyses were conducted using univariate/multivariate analysis and log-rank analysis with SPSS 23.0. Cell models and xenograft models were used to examine the overexpression of OTX1 in vivo and in vitro. OTX1 was overexpressed in ESCC tissues compared with normal esophageal tissues. Both the mRNA expression level and protein level of OTX1 were higher than they were in paired normal tissue. Prognostic and OS analyses showed that the OTX1 expression level was an individual prognostic factor in ESCC patients. Cell viability was significantly promoted when OTX1 was overexpressed in ESCC cell, Furthermore, downregulating OTX1 in EC109 cell significantly attenuated the cell proliferation migration and invasion. Flow cytometric detection showed that cells overexpressing OTX1 were predominantly in the S and G2&M phases. In the xenograft model, both tumor size and weight in the OTX1 overexpression group were significantly larger than those in the control group. OTX1 is an independent prognostic factor of ESCC and contributes to tumorigenesis both in vivo and in vitro.