Causes of hOCT1-Dependent Cholangiocarcinoma Resistance to Sorafenib and Sensitization by Tumor-Selective Gene
Elisa Lozano1,2, Rocio I R Macias1,2, Maria J Monte1,2
1Experimental Hepatology and Drug Targeting (HEVEFARM), IBSAL, University of Salamanca, Salamanca, Spain.
Abstract:
Although the multi-tyrosine kinase inhibitor sorafenib is useful in the treatment of several cancers, cholangiocarcinoma (CCA) is refractory to this drug. Among other mechanisms of chemoresistance, impaired uptake through human organic cation transporter type 1 (hOCT1) (gene SLC22A1) has been suggested. Here we have investigated the events accounting for this phenotypic characteristic and have evaluated the interest of selective gene therapy strategies to overcome this limitation. Gene expression and DNA methylation of SLC22A1 were analyzed using intrahepatic (iCCA) and extrahepatic (eCCA) biopsies (Copenhagen and Salamanca cohorts; n = 132) and The Cancer Genome Atlas (TCGA)-CHOL (n = 36). Decreased hOCT1 mRNA correlated with hypermethylation status of the SLC22A1 promoter. Treatment of CCA cells with decitabine (demethylating agent) or butyrate (histone deacetylase inhibitor) restored hOCT1 expression and increased sorafenib uptake. MicroRNAs able to induce hOCT1 mRNA decay were analyzed in paired samples of TCGA-CHOL (n = 9) and Copenhagen (n = 57) cohorts. Consistent up-regulation in tumor tissue was found for miR-141 and miR-330. High proportion of aberrant hOCT1 mRNA splicing in CCA was also seen. Lentiviral-mediated transduction of eCCA (EGI-1 and TFK-1) and iCCA (HuCCT1) cells with hOCT1 enhanced sorafenib uptake and cytotoxic effects. In chemically induced CCA in rats, reduced rOct1 expression was accompanied by impaired sorafenib uptake. In xenograft models of eCCA cells implanted in mouse liver, poor response to sorafenib was observed. However, tumor growth was markedly reduced by cotreatment with sorafenib and adenoviral vectors encoding hOCT1 under the control of the BIRC5 promoter, a gene highly up-regulated in CCA. Conclusion: The reason for impaired hOCT1-mediated sorafenib uptake by CCA is multifactorial. Gene therapy capable of selectively inducing hOCT1 in tumor cells can be considered a potentially useful chemosensitization strategy to improve the response of CCA to sorafenib.
Insights
Cholangiocarcinoma (CCA) is resistant to sorafenib due to impaired uptake via human organic cation transporter 1 (hOCT1). Restoring hOCT1 expression through gene therapy can enhance sorafenib effectiveness in treating CCA.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Cholangiocarcinoma (CCA) exhibits resistance to sorafenib, a multi-tyrosine kinase inhibitor.
- Impaired uptake of sorafenib, potentially mediated by human organic cation transporter 1 (hOCT1), is a suggested mechanism for chemoresistance in CCA.
Purpose of the Study:
- To investigate the mechanisms behind impaired hOCT1-mediated sorafenib uptake in CCA.
- To evaluate the potential of selective gene therapy strategies to overcome this limitation and improve sorafenib efficacy.
Main Methods:
- Analysis of SLC22A1 gene expression and DNA methylation in CCA patient cohorts and The Cancer Genome Atlas (TCGA).
- Treatment of CCA cells with decitabine and butyrate to assess effects on hOCT1 expression.
- Investigation of microRNA involvement and hOCT1 mRNA splicing.
- In vitro and in vivo studies using lentiviral and adenoviral vectors for hOCT1 gene delivery.
Main Results:
- Decreased hOCT1 mRNA levels in CCA correlated with SLC22A1 promoter hypermethylation.
- Decitabine and butyrate treatments restored hOCT1 expression and increased sorafenib uptake.
- miR-141 and miR-330 were consistently upregulated in tumor tissues, potentially inducing hOCT1 decay.
- Aberrant hOCT1 mRNA splicing was observed in CCA.
- hOCT1 gene delivery enhanced sorafenib uptake and cytotoxicity in CCA cells and reduced tumor growth in xenograft models when combined with sorafenib.
Conclusions:
- The multifactorial reasons for impaired hOCT1-mediated sorafenib uptake in CCA include gene silencing via hypermethylation, microRNA regulation, and aberrant splicing.
- Selective gene therapy to induce hOCT1 in tumor cells presents a promising strategy for chemosensitization and improving CCA response to sorafenib.
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