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A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
PIP5K1α is Required for Promoting Tumor Progression in Castration-Resistant Prostate Cancer
Tianyan Wang1, Martuza Sarwar1, Jonathan B Whitchurch2
1Department of Molecular Biology, Umeå University, Umeå, Sweden.
Abstract:
PIP5K1α has emerged as a promising drug target for the treatment of castration-resistant prostate cancer (CRPC), as it acts upstream of the PI3K/AKT signaling pathway to promote prostate cancer (PCa) growth, survival and invasion. However, little is known of the molecular actions of PIP5K1α in this process. Here, we show that siRNA-mediated knockdown of PIP5K1α and blockade of PIP5K1α action using its small molecule inhibitor ISA-2011B suppress growth and invasion of CRPC cells. We demonstrate that targeted deletion of the N-terminal domain of PIP5K1α in CRPC cells results in reduced growth and migratory ability of cancer cells. Further, the xenograft tumors lacking the N-terminal domain of PIP5K1α exhibited reduced tumor growth and aggressiveness in xenograft mice as compared to that of controls. The N-terminal domain of PIP5K1α is required for regulation of mRNA expression and protein stability of PIP5K1α. This suggests that the expression and oncogenic activity of PIP5K1α are in part dependent on its N-terminal domain. We further show that PIP5K1α acts as an upstream regulator of the androgen receptor (AR) and AR target genes including CDK1 and MMP9 that are key factors promoting growth, survival and invasion of PCa cells. ISA-2011B exhibited a significant inhibitory effect on AR target genes including CDK1 and MMP9 in CRPC cells with wild-type PIP5K1α and in CRPC cells lacking the N-terminal domain of PIP5K1α. These results indicate that the growth of PIP5K1α-dependent tumors is in part dependent on the integrity of the N-terminal sequence of this kinase. Our study identifies a novel functional mechanism involving PIP5K1α, confirming that PIP5K1α is an intriguing target for cancer treatment, especially for treatment of CRPC.
Insights
Phosphatidylinositol-4-phosphate 5-kinase type 1 alpha (PIP5K1α) drives castration-resistant prostate cancer (CRPC) growth. Inhibiting PIP5K1α or its N-terminal domain reduces tumor progression and invasion, highlighting it as a key therapeutic target.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Castration-resistant prostate cancer (CRPC) remains a significant clinical challenge.
- Phosphatidylinositol-4-phosphate 5-kinase type 1 alpha (PIP5K1α) is implicated in prostate cancer (PCa) progression but its molecular mechanisms are not fully understood.
- PIP5K1α acts upstream of the PI3K/AKT pathway, influencing cancer cell growth, survival, and invasion.
Purpose of the Study:
- To elucidate the molecular actions of PIP5K1α in CRPC.
- To investigate the role of the N-terminal domain of PIP5K1α in CRPC.
- To evaluate PIP5K1α as a therapeutic target for CRPC.
Main Methods:
- siRNA-mediated knockdown of PIP5K1α.
- Inhibition of PIP5K1α using the small molecule ISA-2011B.
- Targeted deletion of the PIP5K1α N-terminal domain in CRPC cells.
- Xenograft mouse models to assess tumor growth and aggressiveness.
- Analysis of mRNA expression and protein stability.
- Investigation of PIP5K1α's regulation of the androgen receptor (AR) and AR target genes (CDK1, MMP9).
Main Results:
- Knockdown or inhibition of PIP5K1α suppressed CRPC cell growth and invasion.
- Deletion of the PIP5K1α N-terminal domain reduced cancer cell growth, migration, and xenograft tumor aggressiveness.
- The N-terminal domain is crucial for PIP5K1α's mRNA expression and protein stability.
- PIP5K1α regulates the androgen receptor (AR) and key AR target genes (CDK1, MMP9) involved in PCa progression.
- ISA-2011B effectively inhibited AR target genes in CRPC cells, irrespective of PIP5K1α N-terminal domain integrity.
Conclusions:
- PIP5K1α's N-terminal domain is essential for its expression, stability, and oncogenic activity in CRPC.
- PIP5K1α acts as an upstream regulator of the AR signaling pathway in prostate cancer.
- PIP5K1α and its N-terminal domain represent a promising therapeutic target for CRPC treatment.
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