Hypomethylation agent decitabine restores drug sensitivity by depressing P-glycoprotein activity through MAPK...

Area of Science:

• Oncology
• Pharmacology
• Molecular Biology

Background:

• Multidrug resistance (MDR) is a major challenge in treating hematological and solid tumors.
• The precise mechanisms by which hypomethylation agents like decitabine (5-Aza-dC) combat MDR are not fully understood.
• P-glycoprotein (P-gp), encoded by the mdr1 gene, is a key mediator of MDR.

Purpose of the Study:

• To investigate the potential of decitabine (5-Aza-dC) to reverse P-gp-mediated MDR.
• To elucidate the underlying molecular mechanisms of decitabine's action in MDR cancer cells.

Main Methods:

• Utilized hematologic (K562/ADR) and solid tumor (MCF-7/ADR) cell lines exhibiting MDR.
• Assessed decitabine's effect on drug sensitivity, P-gp expression, and drug accumulation.
• Performed gene expression profiling and analyzed the involvement of the MAPK signaling pathway.

Main Results:

• Decitabine (5-Aza-dC) dose- and time-dependently reversed MDR in both cell types.
• Increased drug sensitivity was observed in patient leukemic cells with high mdr1 expression.
• While P-gp expression increased, decitabine enhanced adriamycin and rhodamine 123 accumulation, indicating reduced P-gp activity.
• Activation of the MAPK signaling pathway was identified as a key effect of decitabine, and its inhibition increased P-gp activity.

Conclusions:

• Decitabine (5-Aza-dC) restores sensitivity to chemotherapy in P-gp-induced MDR phenotypes.
• The mechanism involves the depression of P-gp activity, partly mediated through the MAPK signaling pathway.
• Decitabine shows promise as a therapeutic agent to overcome MDR in cancer treatment.