The fate of chemoresistance in triple negative breast cancer (TNBC).

Background: Treatment options for women presenting with triple negative breast cancer (TNBC) are limited due to the lack of a therapeutic target and as a result, are managed with standard chemotherapy such as paclitaxel (Taxol®). Following chemotherapy, the ideal tumour response is apoptotic cell death. Post-chemotherapy, cells can maintain viability by undergoing viable cellular responses such as cellular senescence, generating secretomes which can directly enhance the malignant phenotype.

Overexpression of the microRNA miR-433 promotes resistance to paclitaxel through the induction of cellular senescence in ovarian cancer cells.

Annually, ovarian cancer (OC) affects 240,000 women worldwide and is the most lethal gynecological malignancy. High-grade serous OC (HGSOC) is the most common and aggressive OC subtype, characterized by widespread genome changes and chromosomal instability and is consequently poorly responsive to chemotherapy treatment. The objective of this study was to investigate the role of the microRNA miR-433 in the cellular response of OC cells to paclitaxel treatment.

MAD2 downregulation in hypoxia is independent of promoter hypermethylation.

Aberrant expression of the MAD2 protein has been linked to chromosomal instability, malignant transformation and chemoresistance. Although reduced MAD2 expression is well recognised in human cancer cell lines, the mechanism(s) underlying its downregulation remain elusive. The objective of this study was to establish the impact of hypoxia on MAD2 expression and to investigate the potential role of aberrant promoter methylation as a possible mechanism of MAD2 downregulation.

Cellular senescence induced by aberrant MAD2 levels impacts on paclitaxel responsiveness in vitro.

Background: The mitotic arrest deficiency protein 2 (MAD2) is a key component of the mitotic spindle assembly checkpoint, monitoring accurate chromosomal alignment at the metaphase plate before mitosis. MAD2 also has a function in cellular senescence and in a cell's response to microtubule inhibitory (MI) chemotherapy exemplified by paclitaxel.

Methods: Using an siRNA approach, the impact of MAD2 down-regulation on cellular senescence and paclitaxel responsiveness was investigated.

Role of the progesterone receptor (PR) and the PR isoforms in breast cancer.

Known risk factors for breast cancer include overexposure to exogenous or endogenous hormones, namely, estrogen and progesterone. The effects of progesterone acts via two isoforms of the progesterone receptor (PR) termed A (PRA) and B (PRB). There is a single human PR gene with two distinct promoter regions in exon 1 encoding the two isoforms.