| Transient receptor potential(transient receptor,potential,TRP)channels are a non-selective cation channel protein superfamily,are widely distributed in the tissues of mammals,and mainly mediate calcium ions and sodium ions from outside the cell into the cytoplasm.There are seven families: TRPA(ankyrin),TRPC(canonical),TRPM(melastatin)TRPML,(mucolipin),TRPN(Drosophila NOMPC),TRPP(polycystin)and TRPV(vanilloid),which include many members.TRP ion channels involve in a series of physiological processes,including mechanical feeling,pain and temperature sensation,taste,cellular ion homeostasis maintaining,calcium influx mediating,cell growth,hormone secretion and neurotransmitter release regulation.The current study found that ion channel is closely related to the occurrence and development of tumor.The TRPP2 ion channel is also called Polycystin-2(PKD2),was first discovered in polycystic kidney cells,and is closely related to the pathogenesis of polycystic kidney disease.TRPP2 is mainly distributed in kidney,heart,pancreas,intestine,ovary,adrenal gland,bile duct,vascular smooth muscle,and placental tissue,and involved in many physiological functions,such as cell proliferation,fertilization,mating behavior and asymmetric gene expression.But so far,the relationship between TRPP2 ion channel and the tumor is rarely reported in China.Laryngeal cancer is one of the most common malignant tumor in head and neck,about 1-5% in all malignant tumors and 11-22% in malignant tumor of the ear nose and throat.In the recent years,the incidence of laryngeal cancer has a rising trend.The etiology of laryngeal cancer is not still clear.Smoking and alcohol consumption are the main two big reasons in laryngeal cancer.The activation of oncogenes,inhibition of tumor suppressor genes and inactivation of apoptosis related genes are the internal causes of laryngeal cancer.Due to the limitation of surgery,radiotherapy and chemotherapy in the treatment of advanced laryngeal cancer,the emergence of invasion and metas tasis,5 years survival rate is less than 50%,mainly caused by local recurrence,lymph node metastasis and distant metastasis.The biggest problem in the treatment of laryngeal cancer is the invasion and metastasis,in which the molecular mechanism is far from clear.The treatment of the metastasis is limited.Epithelial mesenchymal transition(EMT)is an important step in the invasion and metastasis of epithelial tumors.The present study indicates that the incidence of head and neck squamous cell carcino ma(HNSCC)and breast cancer is closely related to EMT.When EMT occurs,epithelial marker E-cadherin and tight junction protein ZO-1 will be down regulated,however,N-cadherin,mesenchymal marker vimentin and EMT-related transcription factor Snail,Twist and ZEB will be up regulated.The signal pathway in EMT includes STAT3 pathway,TGF-?/Smad pathway,PI3K/Akt pathway,Wnt/?-catenin pathway,Src pathway,Ras-MAPK pathway and integrin signaling pathway,et al.Through the above different pathways,the cytokines will act on the target genes,making the cells get invasive and metastatic ability.At present,it is clear that transforming growth factor beta(TGF-beta)plays a role in the migration and metastasis of tumor.Many Smad proteins(such as Smad2,Smad3 and Smad4)are the natural receptors of TGF-beta and bind with TGF-betathe regulate the transcription of related genes to regulate EMT.Ion channel plays an important role in the process of EMT.Epidermal growth factor(EGF)is a protein that was first discovered in the mouse submandibular gland,exists widely in human and animal body,and can promote or inhibit the growth of many kinds of cells.EGF can bind with EGFR to activate a series of important genes in vivo.These genes are involved in the regulation or induction of cell proliferation and regulation of cell growth.Activation of the EGFR can also activate STAT3/Snail,PI3K/Akt and MAPK/Erk signaling pathways to induce EMT.EGFR is overexpressed in many cancer cells,and is thought to be closely related to the invasion and migration of tumor cells.Some EGFR blockers have been used in the treatment of cancer,especially in lung cancer treatment,and achieved good clinical results.In this study,we divided into two parts to investigate the effects of TRPP2 on EMT in human laryngeal squamous cell carcinoma(HLSCC)cells and the regulation of metastasis pathway of HLSCC,and the regulation role of TRPP2 on EGF-mediated EMT of laryngeal carcinoma.Through the study,we can clarify the role and mechanism of TRPP2 in the invasion and metastasis of HLSCC,and EGF-mediated cell migration of laryngeal cancer.WE also can provide new clues for elucidating the TRPP2 regulation mechanism of invasion and metastasis of laryngeal squamous cell carcinoma.The mechanism will be helpful to the early diagnosis and treatment of laryngeal carcinoma and evaluate the prognosis and help to find a new target for the treatment of laryngeal carcinoma,and provide theoretical and experimental basis for the effective treatment of laryngeal cancer.1.The role and mechanis m of TRPP2 in the invasion and metastasis of HLSCCLaryngeal squamous cell carcinoma is a malignant epithelial tumor.The occurrence and development of HLSCC is closely related to EMT.Ca2+ plays an important role in EMT process.TRPP2 as a Ca2+-permeable cation channel regulates Ca2+ influx plays an important role in the invasion and metastasis of laryngeal carcinoma.We studied the relationship between the expression level of TRPP2 ion channel and tumor stage,pathological grading and prognosis of patients with laryngeal cancer.In addition,we have also studied the relationship between TRPP2 and human laryngeal carcinoma cell line Hep2 and the possible mechanism of the regulation of EMT.The results were as follows:(1)the expression level of TRPP2 was significantly increased in laryngeal carcinoma specimens.When the expression level of TRPP2 was increased,the degree of differentiation of tumor cells in patients with laryngeal cancer patients was worse,the higher the degree of malignancy occurred in tumor cells in patients wit h laryngeal cancer patients;(2)the higher the level of TRPP2 expression,the worse the prognosis of patients,the lower the 5 year survival rate;(3)si RN A TRPP2 transfection into Hep2 cells significantly reduced the ATP-induced intracellular Ca2+ release,and the migration and invasion of the tumor in varying degrees;(4)in laryngeal carcinoma Hep2 cells,transfection with TRPP2 si RN A inhibited E-cadherin,Smad4,STAT3,SNAIL,the expression level of SLUG and TWIST.But the expression level of vimentin was increased.O ur data showed that increasing the expression level of TRPP2 can enhance EMT through Smad4 and STAT3 pathways,thereby accelerates the migration and invasion and metastasis of laryngeal squamous cell carcinoma,affects the prognosis and survival rate in 5 years.2.Role of TRPP2 in EGF-mediated cell migration of laryngeal cancer cellsEGF activated STAT3/Snail,PI3K/Akt and MAPK/Erk signaling pathways by acting on EGF receptor(EGFR),resulting in EMT.The former part of the study confirmed that the expression level of TRPP2 was increased and the EMT can be enhanced through the STAT3 and Smad4 pathways.The following results were obtained:(1)the cell migration rate of Hep-2 cells was significantly decreased after transfection with TRPP2 si RN A combining with EGF treatment;(2)under the treatment of EGF,TRPP2 si RNA transfection significantly enhanced the expression of vimentin,but E-cadherin expression was decreased;(3)under the treatment of EGF,the expression level of Smad4 in Hep-2 cells transfected with si RNA TRPP2 was decreased.These results suggest that when TRPP2 ion channel was inhibited Hep-2 cell migration induced by EGF signal pathway was inhibited,resulting in decreased migration ability of Hep-2 cells.Therefore,we speculate that EGF-mediated migration of Hep-2 cells may be modulated by TRPP2 ion channels.TRPP2 can affect the activity of Smad4 dependent signaling pathway and regulate EGF-mediated Hep2 cell migration in laryngeal cancer. |
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