Aberrant DNA Methylation, Expression, and Occurrence of Transcript Variants of the ABC Transporter ABCA7 in Breast Cancer

Epigenetics Meets CAR-T-Cell Therapy to Fight Cancer

Based on the impressive success of Car-T-cell therapy in the treatment of hematological malignancies, a broad application for solid tumors also appears promising. However, some important hurdles need to be overcome. One of these is certainly the identification of specific target antigens on cancer cells. Hypomethylation is a characteristic epigenetic aberration in many tumor entities. Genome-wide screenings for consistent DNA hypomethylations in tumors enable the identification of aberrantly upregulated transcripts, which might result in cell surface proteins. Thus, this approach provides a new perspective for the discovery of potential new Car-T-cell target antigens for almost every tumor entity. First, we focus on this approach as a possible treatment for prostate cancer.

Temperature-Wise Calibration Increases the Accuracy of DNA Methylation Levels Determined by High-Resolution Melting (HRM)

High-resolution melting (HRM) is a cost-efficient tool for targeted DNA methylation analysis. HRM yields the average methylation status across all CpGs in PCR products. Moreover, it provides information on the methylation pattern, e.g., the occurrence of monoallelic methylation. HRM assays have to be calibrated by analyzing DNA methylation standards of known methylation status and mixtures thereof. In general, DNA methylation levels determined by the classical calibration approach, including the whole temperature range in between normalization intervals, are in good agreement with the mean of the DNA methylation status of individual CpGs determined by pyrosequencing (PSQ), the gold standard of targeted DNA methylation analysis. However, the classical calibration approach leads to highly inaccurate results for samples with heterogeneous DNA methylation since they result in more complex melt curves, differing in their shape compared to those of DNA standards and mixtures thereof. Here, we present a novel calibration approach, i.e., temperature-wise calibration. By temperature-wise calibration, methylation profiles over temperature are obtained, which help in finding the optimal calibration range and thus increase the accuracy of HRM data, particularly for heterogeneous DNA methylation. For explaining the principle and demonstrating the potential of the novel calibration approach, we selected the promoter and two enhancers of MGMT, a gene encoding the repair protein MGMT.

Increased Expression of the ABCA1 and ABCA3 Transporter Genes is Associated with Cisplatin Resistance in Breast Cancer Cells

OBJECTIVE

Breast cancer (BC) is a highly malignant neoplasm with resistance to therapeutics that are related to genes associated with multidrug resistance. The excessive expression of ATP-binding cassette transporters (ABCs) genes, including ABCA1 and ABCA3, is a primary factor contributing to the increased effluent of cell-toxic drugs and subsequent treatment resistance. Therefore, the current work aimed to explore the role of ABCA1 and ABCA3 in chemoresistance activity against cisplatin in breast cancer cells.

METHODS

The current study compared the AMJ13 breast cancer cells derived from a woman Iraqi patient, which are hormone receptor-negative, with MCF-7 breast cancer cells, which are hormone receptor-positive.  Cytotoxic assay (CCK-8 assay) is used to measure the cell's viability and cytotoxic activity after it has been treated with cisplatin. Morphological Study using crystal violet stain to examine cytological changes was conducted. Quantitative RT-PCR is used to measure how much the ABCA1, and 3 genes mRNA are being expressed before and after treatment.

RESULTS

The CCK-8 assay found that IC50 values of cisplatin in AMJ13 and MCF-7 cells were 202.2 µg/ml and 90.23 µg/ml, respectively. The IC50 value of AMJ13 is 2-fold higher than in MCF-7 cells. The QPCR study revealed that breast cancer cell lines AMJ13 and MCF-7 subjected to cisplatin showed upregulated levels of ABCA1 and ABCA3 expression. Experiments with cytotoxicity assays demonstrate that higher expression of ABCA1 and ABCA3 in AMJ13 and MCF-7 breast cancer cell lines is linked to their resistance.  Conclusion: The findings of this study suggest that the ABCA1 and ABCA3 transporters play a significant role in the resistance to cisplatin and,.