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Published on: July 17, 2020
The Par-4/PTEN connection in tumor suppression
Maria T Diaz-Meco1, Shadi Abu-Baker
1Department of Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA. maria.diazmeco@uc.edu
Abstract:
Tumor suppressors function in a coordinated regulatory network, and their inactivation is a key step in carcinogenesis. The tumor suppressor Par-4 is a novel integral player in the PTEN network. Thus, Par-4 is absent in a high percentage of human prostate carcinomas, and its loss is concomitantly associated with PTEN loss. Genetic ablation of Par-4 induces fully invasive prostate carcinomas in PTEN-heterozygous mice. In contrast, Par-4 deficiency alone, like PTEN heterozygosis, results in lesions that are unable to progress beyond the benign neoplastic stage known as PIN. At this PIN transition, the mutual induction of Par-4 and PTEN is an additional regulatory step in preventing cancer progression. Par-4 deficiency cooperates with PTEN haploinsufficiency in prostate cancer initiation and progression and their simultaneous inactivation, in addition to enhancing Akt activation, sets in motion a unique mechanism involving the synergistic activation of NFkappaB. These results suggest that the concurrent interruption of complementary signaling pathways targeting PI3K/Akt and NFkappaB activation could provide new and effective strategies for cancer therapy.
Insights
Loss of tumor suppressor Par-4, often seen with PTEN loss in prostate cancer, drives tumor progression. Restoring both Par-4 and PTEN pathways may offer new cancer therapies.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Genetics
Background:
- Tumor suppressors are crucial for preventing cancer by functioning within coordinated regulatory networks.
- Inactivation of tumor suppressors is a critical event in the development of cancer.
- The tumor suppressor Par-4 is identified as a key component within the PTEN regulatory network.
Purpose of the Study:
- To investigate the role of the tumor suppressor Par-4 in prostate cancer development and progression.
- To elucidate the relationship between Par-4 and PTEN in the context of prostate carcinogenesis.
- To explore the therapeutic potential of targeting complementary signaling pathways in prostate cancer.
Main Methods:
- Analysis of Par-4 expression in human prostate carcinomas.
- Genetic ablation of Par-4 in PTEN-heterozygous mice models.
- Assessment of prostate intraepithelial neoplasia (PIN) progression and invasive carcinoma development.
- Investigation of signaling pathways including Akt and NF-kappaB activation.
Main Results:
- Par-4 is frequently absent in human prostate carcinomas, correlating with PTEN loss.
- Genetic deletion of Par-4 in PTEN-heterozygous mice leads to invasive prostate carcinomas.
- Par-4 deficiency alone or PTEN heterozygosity results in non-progressive benign neoplastic lesions (PIN).
- Simultaneous inactivation of Par-4 and PTEN enhances Akt activation and synergistically activates NF-kappaB.
- A regulatory feedback loop between Par-4 and PTEN is identified at the PIN transition stage, crucial for preventing cancer progression.
Conclusions:
- Par-4 deficiency cooperates with PTEN haploinsufficiency in prostate cancer initiation and progression.
- The simultaneous loss of Par-4 and PTEN activates unique synergistic mechanisms involving PI3K/Akt and NF-kappaB pathways.
- Targeting both PI3K/Akt and NF-kappaB signaling pathways concurrently presents a promising therapeutic strategy for prostate cancer.
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