3,3’-Diindolylmethane Regulation Of Epithelial Mesenchymal Transition Inhibits Invasion And Metastasis Of Nasopharyngeal Carcinoma Cells In Vitro And In Vivo

Background Nasopharyngeal carcinoma originates from the epithelial lining of nasopharynx, and it occurs more often in southern China, Southeast Asia, North Africa, Alaska and Greenland. Nasopharyngeal carcinoma offen occurs hiddenly, and because of its non-specific early symptoms and special growth area, patients or doctors can not be aware of these symptoms easily, resulting in misdiagnosis and cervical lymph node metastasi. Nasopharyngeal carcinoma is sensitive of radiotherapy, however, due to the onset of the hidden parts of nasopharynx and its early symptoms are not typical, most patients have been found cervical lymph node metastasis when first diagnosed. Radiotherapy treatment alone is not satisfactory when patients have entered the late stage. Traditional chemotherapy is limited to nasopharyngeal carcinoma with cervical lymph node metastasis, and have significant side effects to normal tissues and organs, patients are often hard to tolerate it. Lymph node status is affecting overall survival without distant metastasis and independent prognostic factors in patients with nasopharyngeal carcinoma, so inhibiting metastasis of nasopharyngeal carcinoma becomes one of the most important aspects of prevention and treatment of nasopharyngeal carcinoma.Epithelial-mesenchymal transition refers to epithelial cells in morphology of fibroblasts or mesenchymal cell phenotype transformation and migration ability to obtain, it is a basic physiological and pathological phenomena and plays an important role in embryonic developmentin and histogenesis. Epithelial-mesenchymal transition is also involved in the formation of a variety of fibrotic diseases, tumor invasion and metastasis occurrence and development and other processes. In the site of metastasis, many cancer cells exhibit epithelial-mesenchymal transition. This is a sign of spread of the original tumor. Currently, epithelial-mesenchymal transition may be related to epithelial-mesenchymal markers characteristic transformation, transcription factor, growth factors, and other relevant micro-environment and MicroRNAs. Cell adhesion loss mediated by E-cadherin is an important initial step in the process of tumor cell invasion and metastasis. E-cadherin loss of function or reducing expression of E-cadherin induces adhesion function impaired, loose tumor cells can escape from the primary tumor and metastasis easily. Vimentin is a clinical prognostic indicator about poor prognosis in variety of tumors and associated with a variety of tumor cells with abnormally high expression of invasion and metastasis. Snail transcription factor plays an important role in the regulation of embryonic EMT. In most epithelial cancer cells expressing high snail and E-cadherin inverse relationship exists in mRNA and protein levels. Slug is also involved in inhibiting the expression of E-cadherin, and increasing expression of vimentin. MMP-9is involved in the degradation of the extracellular matrix and basement membrane of the main actors. MMP-9degradation of extracellular matrix protein fragments can regulate epithelial cell proliferation, invasion, apoptosis and migration, in favor of tumor invasion and metastasis.Crucifers such as broccoli, cauliflower and carrots are known as natural plant with antitumor activity.3,3’-Diindolylmethane is a kind of specific molecular formula of natural compounds which extracted from crucifer, and is the key ingredient of playing antitumor function of crucifer. In addition, there are no signs of toxicity in normal tissues and organs in animal experiment.In our study, we have tested the ability of3,3’-Diindolylmethane of inhibiting invasion and metastasis of nasopharyngeal carcinoma cells in vitro and in vivo。Methods Flow cytometry was used to detect apoptosis rates of the human nasopharyngeal carcinoma cell line5-8F of each group. CCK-8was used to detect survival rates of the human nasopharyngeal carcinoma cell line5-8F of each group. And the nucleus of he human nasopharyngeal carcinoma cell line5-8F were detected by Hoechst33342. PI single staining for detection of cell cycle of the human nasopharyngeal carcinoma cell line5-8F of each group. The migration and invasive ability of the human nasopharyngeal carcinoma cell line5-8F were detected by transwell assay. Lymph node metastasis in nude mice was observed when they got xenograft tumors for8weeks in each group. And western blot were used to detect the expression of EMT related key proteins in NPC cells treated by DIM in vitro and in vivo.Results3,3’-Diindolylmethane can increase the apoptosis rates and reduce the survival rates of the human nasopharyngeal carcinoma cell line5-8F.3,3’-Diindolylmethane can induce G2/M stage arrest of nasopharyngeal carcinoma cells.3,3’-Diindolylmethane can effectively inhibit migration and invasion of nasopharyngeal carcinoma cells in vitro, and the effect was concentration dependent. Meanwhile,3, 3’-Diindolylmethane can significantly delay the occurrence of lymph node metastasis in animal experiment, and reduce the lymph node metastasis. And the expressions of multiple key proteins related to epithelial mesenchymal transition were effectively changed by3,3’-Diindolylmethane. In animal experiment, there were no signs of toxicity of the vital organs such as heart, liver, kidney, of animals feed with3,3-Diindolylmethane.Conclusion DIM can increase the apoptosis rates and reduce the survival rates of the human nasopharyngeal carcinoma cell line5-8F. Meantimes, DIM can induce G2/M stage arrest of nasopharyngeal carcinoma cells.3,3’-Diindolylmethane can effectively change the expressions of epithelial mesenchymal transition related multiple key proteins, and induce the inhibition of invasion and metastasis of nasopharyngeal carcinoma cells in vitro and in vivo.