Profiles of Caspase Activation and Gene Expression in Human Breast Cancer Cell Line MCF-7, after Cyclophosphamide, Doxorubicin, 5-Fluorouracil (CDF) Multi-Drug Administration

The multidrug treatment, CDF [cyclophosphamide (CPA), doxorubicin (DXR), and 5fluorouracil (5-FU)], is a common chemotherapy protocol for breast cancer. However, the molecular mechanisms underlying its toxicity for breast cancer cells remain unclear. As a laboratory model of breast cancer chemotherapy, the human breast cancer cell line MCF-7 was treated with CDF or the individual CDF reagents. Western blotting analysis revealed that two effector caspases (-6 and -7) were activated following the administration of DXR, 5-FU, or the CDF multi-drug. However, after treatment with CPA alone, caspase-7 was activated, but caspase-6 was not. We next used the RNA arbitrarily primedPCR differential display (RAP-PCR DD) method, a derivative of the differential display method, to reveal changes in gene expression with the individual or multi-anticancer drug treatment. RAP-PCR DD was performed using arbitrary PCR primers. Independent cDNA bands representing at least nine mRNA species were amplified after drug treatment. Our results strongly suggested that the administration of different single and multi-anticancer drug treatments induced the expression of several different genes, whose products may be involved in the induction of cancer cell death.