MUC1 Promotes Lymph Node Metastasis In Esophageal Squamous Cell Carcinoma By Downregulating DNAJB6 Expression

Background:Esophageal cancer is a malignant tumor of the digestive tract with high morbidity and mortality.Its histopathological types are divided into esophageal squamous cell carcinoma and esophageal adenocarcinoma.The incidence of esophageal cancer has obvious regional characteristics,and the main pathological type of esophageal cancer in China is esophageal squamous cell carcinoma.It is characterized by rapid progression and early lymph node metastasis.A growing body of evidence has confirmed the important role of MUC1 in the progression of a variety of malignant tumors,including esophageal squamous cell carcinoma.A number of studies have revealed the molecular mechanism by which MUC1-C promotes the malignant biological behavior of cancer cells through different subcellular localization.DNAJB6a levels are frequently decreased in some highly malignant tumors,and aberrant expression of DNAJB6 is associated with the progression of ESCC,but the role of DNAJB6 in the malignant biological behavior of ESCC and the underlying molecular mechanisms of MUC1 and DNAJB6 in ESCC remain unclear.Objective:In this study,we aimed to explore the correlation between MUC1 and DNAJB6,identify the role of DNAJB6 in the progression of ESCC and reveal the underlying molecular mechanism of the MUC1-DNAJB6 axis.Methods:The expression levels of MUC1 and DNAJB6 in esophageal squamous cell carcinoma(ESCC)tissues were detected by IHC assay.The clinical data of 59 patients with esophageal squamous cell carcinoma who underwent radical resection in Shandong Provincial Hospital were retrospectively studied.Combined with the expression levels of MUC1 and DNAJB6 in tumor tissues,the relationship between MUC1 and DNAJB6 expression levels and prognosis was explored.Real-Time qRT-PCR and western blotting were used to examine the expression of MUC1 and DNAJB6 in ESCC cell lines.The effects of MUC1/DNAJB6 on the proliferation,migration and invasion of esophageal squamous cell carcinoma cells were detected by cell counting kit-8(CCK8)assay,wound healing assay and transwell assay.western blot was used to detect the effect of MUC1 overexpression/targeting on the activation of AKT/HSF-1 pathway.In addition,a nude mouse xenograft model was established to further investigate the effect of DNAJB6 up-regulation on MUC1 and tumor proliferation.Results:The results of immunohistochemistry showed that the expression of DNAJB6 and MUC1 in esophageal squamous cell carcinoma tissues was negatively correlated,and the high expression of MUC1 and low expression of DNAJB6 were positively correlated with TNM stage,lymph node metastasis and poor prognosis of patients.In vitro experiments showed that MUC1 could down-regulate the expression of DNAJB6,promote ESCC proliferation,invasion,migration and activate AKT pathway,while overexpression of DNAJB6 could inhibit the proliferation,invasion,migration and AKT pathway of ESCC after MUC1 overexpression.In addition,MUC1 increases HSF-1 phosphorylation through the AKT pathway,and inhibition of AKt-HSF-1 increases DNAJB6 expression.The growth curve of subcutaneous transplanted tumor in nude mice showed that up-regulation of DNAJB6 inhibited the tumorigenic ability of esophageal squamous cell carcinoma cells overexpressing MUC1.Conclusion:This study indicated that MUC1 could promote the lymph node metastasis in ESCC by downregulating DNAJB6 expression.