The Biological Function And Molecular Mechanism Of LINC00638 In ESCC

Esophageal cancer is one of the most common tumor in our country,the incidence ranks the third among men and the fifth among women in China.The histological type of esophageal cancer in our country is mostly esophageal squamous cell carcinoma.At present,the therapeutic method of esophageal squamous cell carcinoma is limited,patients with ESCC have poor prognosis,the five year survival rate is low.Therefore,using biological method to study the molecular mechanism of carcinoma development and progression is urgent.It can provide molecular markers or drug targets for clinic diagnosis and therapy.Through whole-genome sequencing and array comparative genomic hybridization analysis,we found a significantly amplified region 14q32.2-32.33 in patients with ESCC and associated with regional lymph node involvement in previous study.In order to investigate the function and mechanism of long noncoding RNA in ESCC,we selected a long noncoding RNA in ESCC cell within this region,and it's expression is associated with the DNA amplification,named linc00638.we identified the full length nucleotide sequence by RACE assay,Northern blot assay,and PCR assay.During the in situ hybridization of ESCC tissues,we found that the distribution was changed,linc00638 localized in nucleus in 166 cases adjacent normal tissues,but linc00638 localized in nucleus and cytoplasm in 84 cases ESCC tissues,and the cases with a higher lymph node metastasis.To illustrate the molecular mechanism of location change of linc00638,we conducted RNA pull-down assay and MS assay and found that PTB can interact with linc00638,regulate the expression and distribution of linc00638.We conducted comprehensive assay in vivo and in vitro,and found linc00638 can promote cell proliferation,colony formation,migration and invasion,promote HDLEC migration and tube fonnation,promote ESCC cell lymph node metastasis in vivo.These results indicate linc00638 can promote cancer development.Molecular mechanism study found that the linc00638 in cytoplasm can bind VEGF-C mRNA directly,and enhance the stability of mRNA,increase the expression of VEGF-C;linc00638 can interact with miR-216b and regulate the expression of KRAS,which is a target gene of miR-216b.Our study demonstrate that linc00638 is important for ECSS development and progression at first time,that will provide the theory basis and biomarker for diagnosis and treatment for ESCC in the furture.