Expression Of MACC1 In Nasopharyngeal Carcinoma And Its Regulating Effect Of Radiosensitivity Via EMT

BackgroundNasopharyngeal carcinoma(NPC)is a malignant tumor that arises from the squamous epithelial cells of the nasopharynx.NPC is highly prevalent in East and Southeast Asia,especially Southern China,with the incidence rate as high as 25 to 50 per 100,000 Radiotherapy is the preferred radical treatment for NPC.In recent years,the 5-year local control rate of NPC has reached more than 90%,and the 5-year survival rate has reached more than 80%.However,the local recurrence and distant metastasis rates nearly 20-30%after radical radiotherapy for NPC are still the biggest challenge and confusion we are facing.Studies have shown that radiosensitivity is one of the main factors affecting the therapeutic effect of NPC.Therefore,it is urgent to explore the internal molecular mechanism of radiosensitivity of NPC and find new targets for radiotherapy sensitization.Metastasis-associated in colon cancer 1(MACC 1)is highly expressed in a variety of cancers and promotes tumor progression and metastasis by mediating epithelial-mesenchymal transition(EMT)in tumor cells.In recent years,the role of EMT in radiosensitivity of NPC has been paid more and more attention.However,Whether MACC1 is involved in radiosensitivity regulation of NPC via EMT has not been reported.ObjectivesTo investigate the expression of MACC1 in NPC and its regulating effect of radiosensitivity via EMT and to seek new targets for radiotherapy sensitization of NPC.Research Method1.The expression of MACC1 and EMT-related E-cadherin and Vimentin in NPC were assessed by Immunohistochemistry and real-time quantitative PCR.2.The NPC HNE-1 cell line with relatively high expression of MACC1,was used to construct the stable knockdown of MACC1 expression and negative control cell line by RNA interference technique,which HNE-1 cell line was infected by lentivirus vector connected with MACC 1 interfering plasmid.3.The effect of knockdown MACC1 on radiosensitivity of NPC cells was assessed by Cloning formation experiment assay.4.The effects of knockdown MACC1 on proliferation,apoptosis and cell cycle of NPC cells with or without X-ray irradiation were studied by MTT and flow cytometry.5.The effect of knockdown MACC1 on tumorigenesis of NPC cells was assessed by subcutaneous xenograft in nude mice.6.The effects of knockdown MACC1 on expression of E-cadherin,Vimentin,TGFβⅡ and P-Smad3 in NPC cells with or without X-ray irradiation were assessed by Western blot and real-time quantitative PCR.Research Result1.MACC1 is highly expressed in NPC.,MACC1 expression was positively correlated with Vimentin,and negatively correlated with E-cadherin,while Vimentin expression was negatively correlated with E-cadherin.2.High expression of MACC1 and Vimentin and low expression of E-cadherin were associated with poor prognosis of 5-year overall survival,5-year metastasis-free survival,5-year recurrence-free survival and 5-year disease-free survival.3.A stable knockdown MACC 1 expressing HNE-1 cell line(sh-MACC1)and a negative control cell line(sh-NC)were successfully constructed.4.Knockdown MACC1 inhibited proliferation,in vivo tumorigenesis,clonogenesis and cell cycle progression,induced apoptosis,and improveed radiosensitivity of nasopharyngeal carcinoma cells.5.X-ray irradiation in sh-MACC1 cell lines significantly inhibited cell proliferation,promoted cell cycle G0/G1 arrest,and induced apoptosis.6.Knockdown MACC1 inhibited TGFβR Ⅱ/P-Smad3 signaling pathway,downregulated expression of Vimentin,TGFβRⅡ and p-Smad3,up-regulated expression of E-cadherin.7.X-ray irradiation in sh-MACC1 cell lines significantly inhibited TGFβRⅡ/PSmad3 signaling pathway,down-regulated expression of Vimentin,TGFβR Ⅱ and pSmad3,up-regulated expression of E-cadherin.ConclusionMACC1 is highly expressed in NPC..Knockdown of MACC1 expression inhibited cell proliferation,in vivo tumorigenesis and clonogenesis,led to cell cycle G0/G1 arrest,induced apoptosis,and improved radiotherapy sensitivity of NPC cells.The molecular mechanism may be related to the inhibition of TGFβR Ⅱ/PSmad3,the main signaling pathway of EMT,with Vimentin,TGFβR Ⅱ and P-Smad3 down-regulated,and E-cadherin up-regulated.