Functional genetic variants of CTNNBIP1 predict platinum treatment response of Chinese epithelial ovarian cancer patients

Abstract

Chemotherapy resistance remains a blockade for successful treatment and longer overall survival of patients with epithelial ovarian cancer (EOC). CTNNBIP1 is an inhibitor of β-catenin that is a chemotherapeutic target for EOC treatment. In the present study, we investigated associations between single nucleotide polymorphisms (SNPs) of CTNNBIP1 and platinum treatment response of Han Chinese EOC patients and subsequently performed functional prediction and validation of the resultant SNPs. We found that CTNNBIP1 rs935072 AT/TT variant genotypes were associated with platinum treatment response in the multivariate logistic regression analysis of EOC patients. Specifically, the CTNNBIP1 rs935072 AT/TT genotypes were associated with a decreased risk of developing chemoresistance ([adjusted odds ratio (OR)] = 0.89, 95% confidence interval (CI) = 0.82-0.97 and P=0.010), compared with the AA genotype. Further experiments showed that the underlying mechanism for the CTNNBIP1 rs935072 A>T change in chemotherapy treatment response resulted from a lower binding affinity of miR-27a-3p, thereby leading to up-regulation of the CTNNBIP1 expression. We further found that overexpression of CTNNBIP1 sensitized ovarian cancer cells to platinum treatment. Thus, the present study provides evidence that functional variants of CTNNBIP1 may regulate the expression of CTNNBIP1, a possible mechanism affecting platinum treatment response of EOC patients.

Keywords: CTNNBIP1; genetic variants, single nucleotide polymorphisms; ovarian cancer; platinum treatment response.

Figure 1

The study analysis flowchart.

Figure 2

Functional prediction of genetic variants of CTNNBIP1. A, The impact of CTNNBIP1 rs935072 SNP on the mRNA expression of CTNNBIP1 in whole blood tissues from the GTEx database. B, The impact of CTNNBIP1 rs935072 SNP on the mRNA expression of CTNNBIP1 in ovary tissues from the GTEx database. c, CTNNBIP1 expression in different stage of ovarian cancer tissues from TCGA database. TPM, Transcripts per Kilobase of an exon model per Million mapped reads. C, CTNNBIP1 expression in different histology of ovarian cancer tissues from Oncomine database.

Figure 3

The CTNNBIP1 rs935072 A>T contributes to the decreased binding affinity of miR-27a-3p to the CTNNBIP1 3'UTR and increased the expression of CTNNBIP1. A, Graphic representation of the detailed location of rs935072 in the 3'UTR of CTNNBIP1, which is also at the miRNA-binding site with the A allele. B, Schematic drawing of the luciferase reporter system. C, Sequencing results of the Psi-CHECK2 vector containing rs935072 A or T allele. Abbreviation: Mut, Mutagenesis. D-E, Luciferase activity in the presence of the miR-27a-3p transfected into IGROV1 and OVACR-8 cell lines. F, The expression of CTNNBIP1 was detected by the qRT-PCR assay in IGROV1 and OVACR-8 cells overexpressing miR-27a-3p and control cells. G, The expression of CTNNBIP1 was detected by western blot assay in IGROV1 and OVACR-8 cells overexpressing miR-27a-3p and control cells. * P < 0.05. ** P < 0.01.

Figure 4

CTNNBIP1 sensitizes ovarian cancer cells to cisplatin. A-B, Cell Counting Kit-8 assays showed the effect of empty vector and CTNNBIP1 overexpression on the chemosensitivity of ovarian cancer cells to the cytotoxic effect of cisplatin. C-D, Colony formation assays showed the effect of empty vector and CTNNBIP1 overexpression on the chemosensitivity of ovarian cancer cells to the cytotoxic effect of cisplatin. E, The percentage of apoptotic cells in indicated group after cisplatin treatment. Cells were stained with annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) to detect cells in early apoptosis (annexin V+ PI-) and late apoptosis (annexin V+ PI+). Representative pictures are shown. * P < 0.05. ** P < 0.01.