Comparison of Palbosiklib and Ribosiklib in terms of molecular activity and intracellular pathways in hormone receptor positive breast cancer cell lines

Breast cancer is the most common cancer in women. It is the second most common cancer that results in mortality in female cancers. Chemotherapy, hormonotherapy, radiotherapy, monoclonal antibodies in breast cancer as well as effective treatments for new pathways are being developed. Despite the fact that apoptosis is the most important mechanism of action of existing chemotherapeutic agents, these mechanisms of action differ in newly developed drugs. Palbociclib and ribociclib are new agents that have been recently used in breast cancer as cyclin-dependent kinase 4/6 (CDK 4/6) inhibitors, which have an important role in the cell cycle. These two drugs differ in terms of molecular activity and cell death mechanisms as they affect the same pathway. In this study, although two different CDK 4/6 inhibitors inhibited CDK 4/6 in the same pathway in HR + cell cultures (MCF-7 and BT474) containing two of the most common molecular subtypes of breast cancer, luminal-A and luminal- the comparison of cytotoxicity in these cell cultures, the resistance mechanisms that may lead to new combinations, and the detection of cell death mechanisms are planned.