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Protein kinase Cα protects against multidrug resistance in human colon cancer cells

Se-Kyoung Lee1, Adeeb Shehzad, Jae-Chang Jung

  • 1School of Life Sciences, Kyungpook National University, Daegu 702-701, Korea.

Molecules and Cells
|May 29, 2012
PubMed

Insights

Protein kinase C alpha (PKCα) drives multidrug resistance (MDR) in colon cancer by preventing doxorubicin-induced apoptosis. Inhibiting PKCα restores sensitivity to chemotherapy, offering a new strategy against drug-resistant cancers.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Multidrug resistance (MDR) is a major challenge in cancer chemotherapy, where cancer cells evade cytotoxic drugs.
  • ATP-binding cassette (ABC) transporters, like P-glycoprotein (P-gp), mediate drug efflux, contributing significantly to MDR.
  • Protein kinase C (PKC) signaling pathways are implicated in regulating MDR phenotypes.

Purpose of the Study:

  • To investigate the role of Protein Kinase C (PKC) isoforms in the development of doxorubicin resistance in human colon cancer cells.
  • To determine if PKCα is involved in mediating the MDR phenotype and protecting cells from doxorubicin-induced apoptosis.
  • To explore the potential of targeting PKCα as a strategy to overcome doxorubicin resistance.

Main Methods:

  • Comparison of P-glycoprotein (P-gp) expression and doxorubicin sensitivity between parental HCT15 cells and doxorubicin-resistant HCT15/DOX cells.
  • Analysis of PKC isoform expression and membrane translocation in both cell lines.
  • Assessment of PKCα's role in doxorubicin-induced apoptosis, reactive oxygen species (ROS) scavenging, and PARP cleavage.
  • Evaluation of the effects of PKCα inhibition (using Go6976) and knockdown (using siRNA) on MDR and apoptosis.

Main Results:

  • HCT15/DOX cells exhibited high P-gp expression and resistance to doxorubicin, unlike sensitive HCT15 cells.
  • PKCα showed significantly increased membrane translocation and expression levels in HCT15/DOX cells compared to HCT15 cells.
  • PKCα overexpression protected HCT15/DOX cells from doxorubicin-induced apoptosis by scavenging ROS and inhibiting PARP cleavage.
  • Inhibition or knockdown of PKCα sensitized resistant cells to doxorubicin, reduced MDR, and increased apoptosis.

Conclusions:

  • Overexpression and activity of PKCα are closely associated with the regulation of the multidrug resistance phenotype in human colon cancer HCT15 cells.
  • PKCα plays a critical role in conferring resistance to doxorubicin by inhibiting apoptosis through ROS scavenging and PARP cleavage inhibition.
  • Targeting PKCα represents a promising therapeutic strategy to overcome doxorubicin resistance in human cancers.

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