Modulación De La Expresión De Genes Asociados A Resistencia A Carboplatino En Líneas Celulares De Cáncer De Ovario Como Mecanismo De Reversión Del Fenotipo Resistente.

Abstract

Ovarian cancer is one of most lethal diseases in female population worldwide. The standard treatment (after surgical resection) is chemotherapy based mainly on carboplatin (CBDCA) and taxane. However, the main obstacle to a better prognosis is resistance to CBDCA. The nature of this resistance is multifactorial and various mechanisms have been involved. Alterations in DNA methylation patterns have been linked to changes at transcriptional level of genes associated with drug resistance. The objective of this work was to establish an association between the transcriptional expression profile and the methylation of the promoter region of BMP2, GGNBP2, CTR1, Glut1 and sFRP4 in a model of resistance to CBDCA. The generation of the CBDCA resistance model was carried out in the A2780 cell line using the methodology -pulse dose-. The transcriptional profile and methylation of the promoter region was evaluated by qPCR and qMSP, as appropriate. Finally, the over-expression of candidate genes was performed by lipotransfection and subsequent viability evaluation (MTT-formazan assay), translocation of phosphatidylserine and cleavage of caspases 3/7. The transcriptional expression of CTR1, Glut1 and sFRP4 decreased significantly in CBDCA resistant A2780 (CBDCA-R-A2780) compared to A2780 sensitive to CBDCA (parental-A2780), being sFRP4 an interesting candidate gene to evaluate for its biological role in drug resistance. On the other hand, the decrease in the levels of transcriptional expression of sFRP4 did not correlate with the methylation status of its promoter region. Overexpression of sFRP4 significantly decreased cell viability at 72h post-transfection (p<0.05). The cytotoxic effect of sFRP4 plus CBDCA showed a significant decrease in cell viability up to 75% (P <0.0001). In addition, the activation of caspase 3/7 was greater in cells with overexpression of sFRP4 and CBDCA, in comparison with the empty vector/CBDCA. These findings suggest that the transcriptional repression of sFRP4 would not be given by a methylation status of its promoter region in A2780- CBDCA-R. Also, overexpression of sFRP4 has a potential chemosensitizing effect to CBDCA in A2780-CBDCA-R.