Synthetic Lethality Induced by Loss of PKC δ and Mutated Ras

Tongbo Zhu1, Lihua Chen, Wei Du

  • 1Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.

Genes & Cancer
|October 30, 2010
PubMed

Insights

Loss of Protein Kinase C delta (PKC δ) triggers apoptosis in Ras-driven cancer cells by upregulating PKC α/β and JNK signaling. This highlights a synthetic lethal interaction crucial for cancer therapy development.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Signaling

Background:

  • Synthetic lethality exists between oncogenic Ha-ras and Protein Kinase C (PKC) loss.
  • Previous work showed PKC α/β knockdown sensitizes Ras-aberrant cells to apoptosis via PKC δ upregulation.

Purpose of the Study:

  • To investigate the role of PKC δ loss in Ras-overexpressing cells.
  • To elucidate the apoptotic pathway triggered by PKC δ deficiency.

Main Methods:

  • Short hairpin RNA (shRNA) mediated knockdown of PKC δ.
  • Overexpression of JNK in NIH3T3/Hras and DU145 prostate cancer cells.
  • Immunoblotting for phosphorylated JNK and cleaved caspase 8.
  • JNK inhibition studies.

Main Results:

  • PKC δ knockdown induced apoptosis in JNK-overexpressing Ras-driven cells.
  • Apoptosis involved upregulation and RACK1-association of PKC α/β with JNK.
  • JNK phosphorylation and caspase 8 cleavage were observed.
  • JNK inhibition abrogated the apoptotic process.

Conclusions:

  • PKC δ loss triggers apoptosis in Ras-driven cancer cells, mediated by PKC α/β and JNK.
  • PKC α/β and δ have opposing roles in maintaining cell survival against oncogenic stress.
  • Targeting this synthetic lethal interaction could be a therapeutic strategy.

Related Concept Videos

The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...
Lethal Alleles02:41

Lethal Alleles

Agouti: A Lethal Allele
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...
In-vitro Mutagenesis01:16

In-vitro Mutagenesis

To learn more about the function of a gene, researchers can observe what happens when the gene is inactivated or “knocked out,” by creating genetically engineered knockout animals. Knockout mice have been particularly useful as models for human diseases such as cancer, Parkinson’s disease, and diabetes.