Our results suggest that upregulation of Twist plays a role in the neoplastic transformation to oesophageal SCC and subsequent development of distant metastasis. Twist may serve as a useful prognostic marker for predicting the development of distant metastasis in oesophageal SCC.

The transcription factors Pea3, Erm, and Er81 can promote cancer initiation and progression in various types of solid tumors. However, their role in esophageal squamous cell carcinoma (ESCC) has not been elucidated. In this study, we found that the expression levels of Pea3 and Erm, but not that of Er81, were significantly higher in ESCC compared with nontumor esophageal epithelium. A high level of Pea3 expression was significantly correlated with a shorter overall survival in a cohort of 81 patients with ESCC and the subgroup with N1 stage tumor (WilcoxonGehan test, P ‫؍‬ 0.016 and P ‫؍‬ 0.001, respectively). Pea3 was overexpressed in seven ESCC cell lines compared with two immortalized esophageal cell lines. Pea3 knockdown reduced cell proliferation and suppressed nonadherent growth, migration, and invasion in ESCC cells in vitro. In addition, Pea3 knockdown in ESCC cells resulted in a down-regulation of phospho-Akt and matrix metalloproteinase 13, whereas a significant positive correlation in the expression levels was observed between Pea3 and phospho-Akt (r ‫؍‬ 0.281, P < 0.013) and between Pea3 and matrix metalloproteinase 13 in the human specimens (r ‫؍‬ 0.462, P < 0.001). Moreover, Pea3 modulated the sensitivity of EC109 cells to doxorubicin, probably via reduced activity of the phosphatidylinositol 3-kinase-Akt-mammalian target of Rapamycin complex 1 pathway on Pea3 knockdown. In conclusion, our results suggest that Pea3 plays an important role in the progression of ESCC. Esophageal squamous cell carcinoma (ESCC) is common among Asian populations. 1 Despite recent advances in the detection of the premalignant lesions and the development of combination therapies, its incidence is increasing, and its outcome remains poor. [2][3][4] Given the poor prognosis of ESCC and its high incidence rate, it is increasingly important to understand the initiation and progression of this type of cancer and to identify the associated prognostic factors.Pea3, Erm, and Er81 belong to the Pea3 subgroup of the Ets transcription factor family. This group of proteins contains several functional domains, and the individual members demonstrate extensive amino acid sequence similarities. 5 The roles of these proteins in mammary gland development and tumorigenesis have also been extensively studied and reviewed. 6 -8 Pea3 group transcription factors promote metastatic development and cancer progression through transcriptional activation of metastasis-related genes, such as matrix metalloproteinases (MMPs) 9 -13 and cyclooxygenase (COX)-2. 14,15 Overexpression of Pea3 also increases the motility and invasiveness of lung cancer cells via activation of the pathway and an increase in COX-2 expression. 16 -18 The prognostic significance of Pea3 has also been demonstrated in various solid tumors. Pea3 is overexpressed in mouse metastatic mammary adenocarcinoma 19 and in human breast cancer, in which its overexpression is also correlated with HER-2 expression and poor prognosis. 20 -23

Emerging evidence has indicated a role of the bone morphogenetic proteins (BMP) in the pathogenesis of certain cancers. The signaling of BMP family members is tightly regulated by their antagonists, including noggin and SOST, which are, in turn, positively regulated by BMP, thereby forming a negative feedback loop. Consequently, the expression of these antagonists should be taken into account in studies on the prognostic significance of BMP. In the present paper, we correlated protein and mRNA expression levels of BMP6, noggin and SOST, alone or in combination, with patient survival in various types of cancer. We found that BMP6 alone was not significantly correlated with esophageal squamous cell carcinoma patient survival. Instead, a high level of inhibitor of differentiation 1, a downstream factor of BMP6, was associated with shorter survival in patients whose tumors stained strongly for BMP6. Knockdown of noggin in esophageal cancer cell line EC109, which expresses BMP6 strongly and SOST weakly, enhanced the non-adherent growth of the cells. Noggin and SOST expression levels, when analyzed alone, were not significantly correlated with patient survival. However, high BMP6 activity, defined by strong BMP6 expression coupled with weak noggin or SOST expression, was significantly associated with shorter survival in esophageal squamous cell carcinoma patients. We further confirmed that BMP6 activity could be used as a prognostic indicator in prostate, bladder and colorectal cancers, using publicly available data on BMP6, noggin and SOST mRNA expression and patient survival. Our results strongly suggest that BMP6, noggin and SOST could be used in combination as a prognostic indicator in cancer progression.