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Complex impacts of PI3K/AKT inhibitors to androgen receptor gene expression in prostate cancer cells.

Liu L, Dong X - PLoS ONE (2014)

Bottom Line: Co-targeting AR and PI3K/AKT signaling has been proposed to be a more effective therapeutic means for CRPC patients.PI3K/AKT inhibitors had various impacts on AR protein expressions primarily through alterations of AR gene transcription initiation and RNA splicing.However, these effects remained unchanged in the presence RNA silencing of the AKT genes.

View Article: PubMed Central - PubMed

Affiliation: The Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada.

ABSTRACT

Background: Androgen deprivation therapy (ADT) is the first-line treatment to metastatic prostate cancer (PCa). However, sustained expression and function of the androgen receptor (AR) gene contribute to the progression of castration resistant prostate cancers (CRPC). Additionally, tumors can adapt the PI3K/AKT survival pathway to escape ADT. Co-targeting AR and PI3K/AKT signaling has been proposed to be a more effective therapeutic means for CRPC patients. Many clinical trials are ongoing to test whether PI3K/AKT inhibitors are beneficial to PCa patients. However whether these inhibitors have any impacts on the expressions of full length AR (AR-FL) and its splice variant (AR-V7) remains unclear.

Methods: Four human prostate cancer cell lines (LNCaP, LNCaP95, VCaP and 22Rv1) with different genetic backgrounds were treated with five PI3K/AKT inhibitors (LY294002, Wortmannin, BKM120, AKTi and AZD5363) and or AKT siRNA. AR and AR-V7 protein and mRNA levels were measured by immunoblotting and real-time PCR assays. AR gene transcription initiation, alternative RNA splicing and AR mRNA degradation rates were also determined.

Results: PI3K/AKT inhibitors had various impacts on AR protein expressions primarily through alterations of AR gene transcription initiation and RNA splicing. However, these effects remained unchanged in the presence RNA silencing of the AKT genes.

Conclusion: PI3K/AKT inhibitors have off-target effects on AR gene expression in prostate cancer cells, which shall be considered when applying these inhibitors to PCa patients, particularly patients under ADT treatment.

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Related in: MedlinePlus

Impacts of PI3K/AKT inhibitors to AR mRNA levels in PCa cells.LNCaP, LNCaP95, VCaP and 22Rv1 cells were treated with increasing doses of PI3K/AKT inhibitors LY294002 (0, 25, 50 uM), Wortmanin (0, 0.5 and 1 uM), BKM120 (0, 0.5 and 1 uM), AKTi (0, 5 and 10 uM) or AZD5363 (0, 2.5 and 5 uM) for 18 hours. AR-FL (A) and AR-V7 (B) mRNA expression levels relative to 18rS were determined by real-time PCR. Results were from three independent RNA extractions with triplicate real-time PCR assays on each RNA sample. Data was plotted as mean+SEM. One-way ANOVA followed by student t-test was performed with * as P<0.05, ** as P<0.01 and *** as P<0.001.
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pone-0108780-g003: Impacts of PI3K/AKT inhibitors to AR mRNA levels in PCa cells.LNCaP, LNCaP95, VCaP and 22Rv1 cells were treated with increasing doses of PI3K/AKT inhibitors LY294002 (0, 25, 50 uM), Wortmanin (0, 0.5 and 1 uM), BKM120 (0, 0.5 and 1 uM), AKTi (0, 5 and 10 uM) or AZD5363 (0, 2.5 and 5 uM) for 18 hours. AR-FL (A) and AR-V7 (B) mRNA expression levels relative to 18rS were determined by real-time PCR. Results were from three independent RNA extractions with triplicate real-time PCR assays on each RNA sample. Data was plotted as mean+SEM. One-way ANOVA followed by student t-test was performed with * as P<0.05, ** as P<0.01 and *** as P<0.001.

Mentions: AR mRNA levels were also measured in PCa cell lines under treatments of PI3K/AKT inhibitors. The changes of AR-FL and AR-V7 mRNA levels (Fig. 3) were consistent to what were observed in AR protein levels as shown in Figure 1 and 2. LY294002 and Wortmannin decreased both AR-FL and AV-7 mRNA levels in all PCa cell lines except that LY294002 increased AR-FL mRNA levels in 22Rv1 cells. BKM120 and AKTi had no significant impacts in AR mRNA levels. AZD5363 increased AR-FL and AR-V7 mRNA levels in LNCaP and LNCaP95 cells, but decreased their mRNA levels in VCaP and 22Rv1 cells with statistical significance. These results suggested that PI3K/AKT inhibitors affected AR gene expression primarily at mRNA level.


Complex impacts of PI3K/AKT inhibitors to androgen receptor gene expression in prostate cancer cells.

Liu L, Dong X - PLoS ONE (2014)

Impacts of PI3K/AKT inhibitors to AR mRNA levels in PCa cells.LNCaP, LNCaP95, VCaP and 22Rv1 cells were treated with increasing doses of PI3K/AKT inhibitors LY294002 (0, 25, 50 uM), Wortmanin (0, 0.5 and 1 uM), BKM120 (0, 0.5 and 1 uM), AKTi (0, 5 and 10 uM) or AZD5363 (0, 2.5 and 5 uM) for 18 hours. AR-FL (A) and AR-V7 (B) mRNA expression levels relative to 18rS were determined by real-time PCR. Results were from three independent RNA extractions with triplicate real-time PCR assays on each RNA sample. Data was plotted as mean+SEM. One-way ANOVA followed by student t-test was performed with * as P<0.05, ** as P<0.01 and *** as P<0.001.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4215833&req=5

pone-0108780-g003: Impacts of PI3K/AKT inhibitors to AR mRNA levels in PCa cells.LNCaP, LNCaP95, VCaP and 22Rv1 cells were treated with increasing doses of PI3K/AKT inhibitors LY294002 (0, 25, 50 uM), Wortmanin (0, 0.5 and 1 uM), BKM120 (0, 0.5 and 1 uM), AKTi (0, 5 and 10 uM) or AZD5363 (0, 2.5 and 5 uM) for 18 hours. AR-FL (A) and AR-V7 (B) mRNA expression levels relative to 18rS were determined by real-time PCR. Results were from three independent RNA extractions with triplicate real-time PCR assays on each RNA sample. Data was plotted as mean+SEM. One-way ANOVA followed by student t-test was performed with * as P<0.05, ** as P<0.01 and *** as P<0.001.
Mentions: AR mRNA levels were also measured in PCa cell lines under treatments of PI3K/AKT inhibitors. The changes of AR-FL and AR-V7 mRNA levels (Fig. 3) were consistent to what were observed in AR protein levels as shown in Figure 1 and 2. LY294002 and Wortmannin decreased both AR-FL and AV-7 mRNA levels in all PCa cell lines except that LY294002 increased AR-FL mRNA levels in 22Rv1 cells. BKM120 and AKTi had no significant impacts in AR mRNA levels. AZD5363 increased AR-FL and AR-V7 mRNA levels in LNCaP and LNCaP95 cells, but decreased their mRNA levels in VCaP and 22Rv1 cells with statistical significance. These results suggested that PI3K/AKT inhibitors affected AR gene expression primarily at mRNA level.

Bottom Line: Co-targeting AR and PI3K/AKT signaling has been proposed to be a more effective therapeutic means for CRPC patients.PI3K/AKT inhibitors had various impacts on AR protein expressions primarily through alterations of AR gene transcription initiation and RNA splicing.However, these effects remained unchanged in the presence RNA silencing of the AKT genes.

View Article: PubMed Central - PubMed

Affiliation: The Vancouver Prostate Centre, Department of Urologic Sciences, University of British Columbia, Vancouver, Canada.

ABSTRACT

Background: Androgen deprivation therapy (ADT) is the first-line treatment to metastatic prostate cancer (PCa). However, sustained expression and function of the androgen receptor (AR) gene contribute to the progression of castration resistant prostate cancers (CRPC). Additionally, tumors can adapt the PI3K/AKT survival pathway to escape ADT. Co-targeting AR and PI3K/AKT signaling has been proposed to be a more effective therapeutic means for CRPC patients. Many clinical trials are ongoing to test whether PI3K/AKT inhibitors are beneficial to PCa patients. However whether these inhibitors have any impacts on the expressions of full length AR (AR-FL) and its splice variant (AR-V7) remains unclear.

Methods: Four human prostate cancer cell lines (LNCaP, LNCaP95, VCaP and 22Rv1) with different genetic backgrounds were treated with five PI3K/AKT inhibitors (LY294002, Wortmannin, BKM120, AKTi and AZD5363) and or AKT siRNA. AR and AR-V7 protein and mRNA levels were measured by immunoblotting and real-time PCR assays. AR gene transcription initiation, alternative RNA splicing and AR mRNA degradation rates were also determined.

Results: PI3K/AKT inhibitors had various impacts on AR protein expressions primarily through alterations of AR gene transcription initiation and RNA splicing. However, these effects remained unchanged in the presence RNA silencing of the AKT genes.

Conclusion: PI3K/AKT inhibitors have off-target effects on AR gene expression in prostate cancer cells, which shall be considered when applying these inhibitors to PCa patients, particularly patients under ADT treatment.

Show MeSH
Related in: MedlinePlus