The latest tumor statistics in China in 2015 showed that the incidence of ECa ranked the third among malignant tumors [3, 4]. The occurrence of ECa was the result of the mutual effect between environmental and genetic factors, among which the former mainly include smoking, excessive drinking, excessive intake of nitrite, and lack of micronutrients [5–8]. Environmental factors are initiating factors, however, the incidence of ECa varies among individuals exposed to the same environment, indicating that individual genetic factors play a key role in the progression of ECa [14].
In recent years, despite advances in diagnosis, surgical treatment, patient care and adjuvant therapy, morbidity and mortality have remained high [15]. In addition to the unclear pathogenesis of ECa, which leads to the failure to formulate and carry out effective preventive measures, the lack of clinical diagnosis and treatment of ECa is also one of the main reasons [15, 16]. At present, clinically targeted tumors such as esophageal cancer still lack very effective molecular diagnostic markers. At the same time, in addition to traditional surgery plus radiotherapy and chemotherapy, the application of gene therapy has been very poor [17, 18]. Fundamentally speaking, the main reason for this situation is the lack of clinical research on target genes. Therefore, identifying marker molecules to detect early esophageal cancer and precancerous lesions, looking for target genes that may be used in gene therapy, and explore the feasibility of their use as therapeutic targets are hot spots in the field of tumor research [7, 8].
The tumor database indicates that ATP6V0C in tumor tissues of ECa patients is dysregulated, indicating that ATP6V0C may act as a carcinogen to cause the occurrence of this cancer, or as a tumor suppressor to prevent it. At present, ATP6V0C was reported to be over-expressed in various cancer tissues, such as prostate cancer and colorectal cancer, and its expression level is closely relevant to clinicopathological characteristics and clinical prognosis. Consistently, this study found that ATP6V0C in ECa tissues was significantly up-regulated and was correlated with the incidence of patients' lymph node and distant metastasis, indicating that ATP6V0C may serve as a cancer-suppressing gene in esophageal cancer. Subsequently, we proved that ATP6V0C enhances the proliferation and invasiveness of ECa and thus play an essential role in this disease.
The innovation of this study lies that we performed a variety of molecular biology technologies and bioinformatics analysis and explored the functions of ATP6V0C in ECa and the potential molecular mechanism. Based on the basic data of a large number of clinical cases with esophageal cancer, the present work elucidated whether the age of esophageal cancer patients and the clinical and pathological staging are correlated with ATP6V0C level. All these findings provided theoretical basis and reference for ATP6V0C as a possible molecular logo that predicts the occurrence of esophageal cancer. Through online data query and prediction, TWF1 was finally predicted to be the target binding gene of ATP6V0C. In this study, luciferase reporter gene experiment confirmed ATP6V0C can bind to the specific sequence of TWF1 gene. Meanwhile, it was confirmed by qPCR that ATP6V0C and TWF1 were positively correlated in ECa tissues, indicating that ATP6V0C may directly target TWF1 and play a positive regulatory role. Consistently, Western Blotting suggested a reduction in TWF1 expression induced by ATP6V0C knockdown. In addition, overexpression of TWF1 offset the inhibitory effect of ATP6V0C knockdown on cell functions, suggesting that ATP6V0C/TWF1 regulatory axis may exert crucial effects on the progression of ECa.
There are also obvious limitations in this article. For example, we have not verified the role of ATP6V0C through TWF1 to regulate the development of esophageal cancer tumors. In addition, we did not verify the role of ATP6V0C in the process by blocking TWF1. In the future, we will conduct animal experiments and further explore and verify the molecular mechanism. At the same time, we will also collect more clinical samples and patient data, the predictive value of ATP6V0C for the prognosis of patients with esophageal cancer was further studied and analyzed.