The Role Of Long Noncoding RNA MALAT1 In Laryngeal And Hypopharyngeal Squamous Cell Carcinoma

Background :Laryngeal cancer is one of the common malignancies which is threaten the human health.Laryngeal squamous cell carcinoma(LSCC)is the most prevalent pathological type of laryngeal cancer and is a sort of ordinary tumors in head and neck cancer,accounting for the otolaryngology tumors 7.9%-35%.In recent years,the happening of laryngocarcinoma increased year by year,and the incidence of different countries and regions are inconsistent.Early laryngeal cancer can be cured by a variety of treatments,but the prognosis of advanced laryngeal cancer is poor,high mortality.The occurrence and development of laryngeal cancer is very complex,involving multiple genes and all kinds of pathways.It is possible that further studies on the regulation of genes may provide new tools for the diagnosis and treatment of laryngeal cancer.Long noncoding RNA(lncRNA)is defined as a group of RNAs(>200 nt)with limited or no coding capacity due to a lack of an intact open reading frame,but participates in most vital biological activities.LncRNAs are important molecular elements in eukaryotic cells,and play key roles in various aspects of m RNA stability,translational regulation,protein transport,RNA processing and modification.Lung adenocarcinoma metastasis-associated transcript 1(MALAT1)is one of the earliest discovered long-chain non-coding RNA,which is about 8700 bp,located in human11q13 chromosome.It was originally screened by subtractive hybridization in a study of human non-small cell lung cancer(NSCLC).Because the lack of a meaningful open-coding frame,it can not translate the corresponding protein in vitro.At the same time,there exists evolutionary conservation in the sequence and highly homologous sequences among species,suggesting that it has an important function in tumorigenesis and development.Research contents:Reverse Transcription Polymerase Chain Reaction(RT-PCR)and QuantitativeReal Time PCR(Q-RT-PCR)are used to detect the expression of MALAT1 at m RNA level in laryngeal squamous cell carcinoma tissues,hypopharyngeal squamous cell carcinoma tissues and normal tissues.It is possible to transfect MALAT1 small interfering RNA(siRNA)into human laryngeal epidermoid carcinoma cell line(Hep-2cell line)and pharyngeal squamous cell carcinoma(FaDu cell line)with lipofectamine 3000,so as to silence the MALAT1 expression.CCK8 assay,colony formation assay and flow cytometry were used to detect the effect on cell apoptosis and proliferation.Transwell assay and scratch assay could be used to discover the effect on cell invasion and migration.Results:(1)At mRNA level,MALAT1 is highly expressed in laryngeal squamous cell carcinoma and hypopharyngeal squamous cell carcinoma compared with adjacent normal tissues(P<0.05);(2)Transwell experiments and scratch experiments show that sliencing the expression of MALAT1 inhibit the invasion and migration of Hep-2 cells and FaDu cells.CCK8 assay and clonogenic assay confirm that knockdown of MALAT1 expression inhibit Hep-2 Apoptosis and proliferation ability of cells and FaDu cells.(3)The apoptosis of Hep-2 cell line and Fadu cell line increased after the knockdown of MALAT1,,and the cell arrest in G1 phase and S phase decreased significantly.Conclusions:Compared with normal tissues,long non-coding RNA MALAT1 was significantly up-regulated in laryngeal and laryngeal squamous cell carcinoma tissues.Down-regulation of MALAT1 expression decreased the invasion and migration of laryngeal squamous cell carcinoma cell lines Hep-2 cells;apoptosis increased and proliferation was inhibited;cells were arrested in G1 phase and S phase cells were significantly decreased.Down-regulation of MALAT1 expression decreased the invasion and migration of Fadu cells in the laryngopharyngeal squamous cell carcinoma cell line.Apoptosis increased and proliferation was inhibited.Cells were arrested in G1 phase and Sphase cells were significantly decreased.