Retrospective analysis of the correlation between MRP2 expression in circulating tumor cells and molecular characteristics of breast cancer

Breast cancer is recognized as one of the most common malignant tumors affecting women, with the challenge of multidrug resistance presenting a particularly critical concern in its therapeutic management. Among the family of ABCC transporter proteins, the MRP2 is prominently expressed in breast cancer tissues and may contribute to the treatment resistance observed in clinical settings. This study aims to elucidate the correlation between the expression levels of MRP2 protein in circulating tumor cells (CTCs) and the molecular characteristics linked to breast cancer. A cohort of 51 patients diagnosed with breast cancer was recruited for this investigation; However, 3 individuals exhibited absent MRP2 expression and were subsequently excluded from the analysis. CTCs were isolated and classified from peripheral blood samples using CanPatrol technology. The expression level of MRP2 was detected using comprehensive multiplex mRNA in situ hybridization, and statistical evaluations, which encompass the χ2 test and multivariate logistic regression analysis, were performed to assess the correlation between MRP2 expression ratio and pathological parameters. Our results showed significant differences in MRP2 expression ratios between estrogen receptor (ER) and progesterone receptor (PR) (P = .021, P = .004), as well as significant differences in subtypes of luminal breast cancer and triple-negative breast cancer (TNBC) (P = .021, P = .048). Multivariate regression analysis indicated that MRP2 expression level also had a statistically significant impact on PR (OR = 0.901; 95% CI 0.814-0.998; P = .046). In the low MRP2 expression group, the pathological type of breast cancer was mainly characterized by positive ER and PR; predominantly luminal type breast cancer. In contrast, in the high MRP2 expression group, the pathological type of breast cancer was mainly characterized by negative ER and PR; predominantly TNBC. High MRP2 expression was independently associated with PR-negative status. In conclusion, the present investigation reveals a noteworthy correlation between elevated levels of MRP2 protein in CTCs and TNBC. This finding deepens our understanding of the molecular mechanisms that contribute to the metastasis of breast cancer and provides a scientific basis for predicting treatment outcomes in breast cancer patients exhibiting elevated levels of MRP2 protein expression.