Abstract

Chemoresistance prevents effective cancer therapy and is rarely predictable prior to treatment, particularly for hepatocellular carcinoma (HCC). Following the chemoresistance profiling of eight HCC cell lines to each of nine chemotherapeutics, two cell lines (QGY-7703 as a sensitive and SMMC-7721 as a resistant cell line to 5-fluorouracil (5-FU) treatment) were systematically studied for mechanistic insights underpinning HCC 5-FU chemoresistance. Genomic profiling at both DNA methylation and microRNA (miR) levels and subsequent mechanistic studies illustrate a new mechanism for how DNA methylation-regulated miR-193a-3p dictates the 5-FU resistance of HCC cells via repression of serine/arginine-rich splicing factor 2 (SRSF2) expression. In turn, SRSF2 preferentially up-regulates the proapoptotic splicing form of caspase 2 (CASP2L) and sensitizes HCC cells to 5-FU. Forced changes of miR-193a-3p level reverse all of the phenotypic features examined, including cell proliferation, cell cycle progression, and 5-FU sensitivity, in cell culture and in nude mice. Importantly, the siRNA-mediated repression of SRSF2 phenocopies all of the miR-193a-3p mimic-triggered changes in QGY-7703. This newly identified miR-193a-3p-SRSF2 axis highlights a new set of companion diagnostics required for optimal 5-FU therapy of HCC, which involve assaying both the DNA methylation state of the miR-193a gene and the expression of miR-193a-3p and SRSF2 and the relative level of the proapoptotic versus antiapoptotic splicing forms of caspase 2 in clinical samples.

Highlights

  • Chemoresistance prevents effective therapy of hepatocellular carcinoma (HCC)

  • Following the chemoresistance profiling of eight HCC cell lines to each of nine chemotherapeutics, two cell lines (QGY-7703 as a sensitive and SMMC-7721 as a resistant cell line to 5-fluorouracil (5-FU) treatment) were systematically studied for mechanistic insights underpinning HCC 5-FU chemoresistance. Genomic profiling at both DNA methylation and microRNA levels and subsequent mechanistic studies illustrate a new mechanism for how DNA methylationregulated miR-193a-3p dictates the 5-FU resistance of HCC cells via repression of serine/arginine-rich splicing factor 2 (SRSF2) expression

  • DNA Methylation-regulated miR-193a-3p Expression Correlates 5-FU Resistance of SMMC-7721 and QGY-7703—The chemoresistance of eight HCC cell lines was determined by IC50 profiling: QGY-7703, SMMC-7721, YY-8103, PLC, HepG2, BEL-7402, Hep3B, and FOCUS to gemcitabine, 5-FU, cisplatin, vinorelbine, docetaxel, mitomycin, paclitaxel, ironotecan, and epirubicin, respectively

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Summary

Background

Chemoresistance prevents effective therapy of hepatocellular carcinoma (HCC). Results: Genomic and mechanistic studies suggested the role of miR-193a-3p via SRSF2 mediates up-regulation of the proapoptotic splicing form of caspase 2 in HCC 5-FU resistance. Following the chemoresistance profiling of eight HCC cell lines to each of nine chemotherapeutics, two cell lines (QGY-7703 as a sensitive and SMMC-7721 as a resistant cell line to 5-fluorouracil (5-FU) treatment) were systematically studied for mechanistic insights underpinning HCC 5-FU chemoresistance Genomic profiling at both DNA methylation and microRNA (miR) levels and subsequent mechanistic studies illustrate a new mechanism for how DNA methylationregulated miR-193a-3p dictates the 5-FU resistance of HCC cells via repression of serine/arginine-rich splicing factor 2 (SRSF2) expression. The siRNA-mediated repression of SRSF2 phenocopies all of the miR-193a-3p mimictriggered changes in QGY-7703 This newly identified miR193a-3p-SRSF2 axis highlights a new set of companion diagnostics required for optimal 5-FU therapy of HCC, which involve assaying both the DNA methylation state of the miR-193a gene and the expression of miR-193a-3p and SRSF2 and the relative. The systematic studies targeting a DNA methylation-regulated miR-193a-3p as the first candidate of several dozen informative defects were studied in detail for both its role in HCC 5-FU resistance and the mechanistic details in both cell culture and a tumor xenograft nude mouse model

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