The Expression Of HnRNP L In Oral Squamous Cell Carcinoma And The Effect Of HnRNP L On SRSF3

Background:Oral squamous cell carcinoma(OSCC)is the most common malignancy of head and neck.Because of the high mortality rates,OSCC is lethal to the human health.However,the mechanisms of initiation and progression of OSCC have not been fully understood.Heterogeneous nuclear ribonucleoproteins(HnRNPs)are a big family of nuclear proteins with more than 20 members,among which hnRNP L is a multifunctional splicing factor.HnRNP L participates a series of RNA-related biological processes,including chromatin modification,export of intronless mRNA,poly(A)site selection,maintenance of mRNA stability and so on.Numerous evidences showed that hnRNP L is closely associated with the formation and development of tumor.But the relationship between hnRNP L and OSCC still remains unknown.Objective:The purpose of this study was to uncover the relationship between hnRNP L and OSCC and the potential mechanisms among it.Methods:1.The expression of hnRNP L in OSCC and normal oral tissues were analyzed by immunohistochemistry,and the correlation of expression between hnRNP L and SRSF3 was analyzed by SPSS.2.HnRNP L or SRSF3 was knocked down or overexpressed in 293 cells and CAL27 cells by transfection.The expression levels of hnRNP L and SRSF3 were quantified by western blotting.3.HnRNP L was knocked down by RNAi in CAL27 cells.Transcription level of SRSF3 and alternative splicing of SRSF3 exon 4 were analyzed by RT-PCR.Results:1.HnRNP L is significantly overexpressed in OSCC tissues,and the expression of hnRNP L and SRSF3 is positively correlated.2.Knockdown or overexpression of hnRNP L repressed or enhanced the expression of SRSF3 in 293 cells and CAL27 cells.Knockdown of SRSF3 in 293 cells and CAL27 cells repressed the expression of hnRNP L.3.Knockdown of hnRNP L decreased the expression level of SRSF3 mRNA and increased the relative inclusion level of exon 4.Conclusion:HnRNP L is overexpressed in OSCC tissues,and the expression levels of hnRNP L and SRSF3 in OSCC tissues are moderately positively correlated.The expression of SRSF3 is regulated by hnRNP L at both transcriptional and post-transcriptional levels.HnRNP L regulates the alternative splicing of SRSF3 exon 4.SRSF3 is a novel target of hnRNP L.