Fig 4. Effect of DNA demethylating agent 5 -aza-2’-dC and HDAC inhibitor TSA on sensitivity of chemotherapeutic drugs doxorubicin and cisplatin in MCF-7^P and MCF-7^E cells as determined by MTT assay for cell viability.

Cells were first pre-treated with 5 -aza-2’-dC and TSA for 24 hr before doxorubicin and cisplatin treatments. The effect of 5 -aza-2’-dC and TSA pre-treatments on chemotherapeutic sensitivity was then determined by MTT assay as described in materials and methods. MTT data was converted into percentage with their respective controls as 100% and histogram was plotted. The error bars represent standard error of the mean (±SEM). Symbols * represent statistically significant difference in viability of various treatment groups (5 -aza-2’-dC+ Doxorubicin, TSA+ Doxorubicin, 5 -aza-2’-dC+ Cisplatin, TSA+ Cisplatin) of MCF-7^P as compared to its untreated MCF-7^P control cells. The symbol # represents statistically significant difference in viability of various treatment groups (Doxorubicin, 5 -aza-2’-dC+ Doxorubicin, TSA+ Doxorubicin, Cisplatin, 5 -aza-2’-dC+ Cisplatin, TSA+ Cisplatin) of MCF-7^E cells as compared to its untreated MCF-7^E control cells. The symbol + represents statistically significant difference in cell viability between MCF-7^E cells and MCF-7^P cells within each treatment groups (5 -aza-2’-dC+ Doxorubicin, TSA+ Doxorubicin, 5 -aza-2’-dC+ Cisplatin).