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Prostate cancer characteristics associated with response to pre-receptor targeting of the androgen axis.

Mostaghel EA, Morgan A, Zhang X, Marck BT, Xia J, Hunter-Merrill R, Gulati R, Plymate S, Vessella RL, Corey E, Higano CS, Matsumoto AM, Montgomery RB, Nelson PS - PLoS ONE (2014)

Bottom Line: In LuCaP96 tumors (T:DHT 10:1), survival was not improved despite similar DHT reduction (0.02 ng/gm).Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression.Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and should be validated in additional models.

View Article: PubMed Central - PubMed

Affiliation: Division of Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America; Department of Medicine, University of Washington School of Medicine, Seattle, Washington, United States of America.

ABSTRACT

Background: Factors influencing differential responses of prostate tumors to androgen receptor (AR) axis-directed therapeutics are poorly understood, and predictors of treatment efficacy are needed. We hypothesized that the efficacy of inhibiting DHT ligand synthesis would associate with intra-tumoral androgen ratios indicative of relative dependence on DHT-mediated growth.

Methods: We characterized two androgen-sensitive prostate cancer xenograft models after androgen suppression by castration in combination with the SRD5A inhibitor, dutasteride, as well as a panel of castration resistant metastases obtained via rapid autopsy.

Results: In LuCaP35 tumors (intra-tumoral T:DHT ratio 2:1) dutasteride suppressed DHT to 0.02 ng/gm and prolonged survival vs. castration alone (337 vs.152 days, HR 2.8, p = 0.0015). In LuCaP96 tumors (T:DHT 10:1), survival was not improved despite similar DHT reduction (0.02 ng/gm). LuCaP35 demonstrated higher expression of steroid biosynthetic enzymes maintaining DHT levels (5-fold higher SRD5A1, 41 fold higher, 99-fold higher RL-HSD, p<0.0001 for both), reconstitution of intra-tumoral DHT (to ∼30% of untreated tumors), and ∼2 fold increased expression of full length AR. In contrast, LuCaP96 demonstrated higher levels of steroid catabolizing enzymes (6.9-fold higher AKR1C2, 3000-fold higher UGT2B15, p = 0.002 and p<0.0001 respectively), persistent suppression of intra-tumoral DHT, and 6-8 fold induction of full length AR and the ligand independent V7 AR splice variant. Human metastases demonstrated bio-active androgen levels and AR full length and AR splice-variant expression consistent with the range observed in xenografts.

Conclusions: Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression. Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and should be validated in additional models.

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Characterization of LuCaP35 and LuCaP96 prostate cancer xenografts and responses to systemic androgen suppression.(A) Representative FFPE samples of each xenograft were stained with hematoxylin and eosin (H&E) and for expression of the androgen receptor (AR) and PSA as indicated. The scale bar (depicted on the PSA figures for ease of visualization) are 50µm. Kaplan-Meier plots of progression free survival (defined as tumor size <750 mm3) in mice bearing LuCaP35 (B) or LuCaP96 (C) xenografts. Intact male SCID mice were implanted subcutaneously with 30 mm3 pieces of the indicated xenografts. When tumors reached ∼300 mm3, mice were randomly enrolled into cohorts that were either left intact (No Cx) or castrated (Cx). P-values for curve comparisons were generated using the Mantel-Haenszel logrank test. (D) Mean and standard deviation of tissue testosterone (T, black bar) and DHT (gray bar) levels measured by mass spectrometry in tumors of the indicated xenograft (passaged in intact mice). (E) Relative expression of transcripts for the indicated steroidogenic genes was calculated using the delta dCt method (fold change = 2∧ddCt). Genes differentially expressed in LuCaP35 vs. LuCaP96 within one order of magnitude are indicated within the gray lines. Significant differences (by Welch’s t test; p<0.05) are indicated by black circles; white circles indicate genes that were not significantly different between LuCaP35 and LuCaP96 (all values given in Supplementary Data 2).Upward triangles indicate highly differentially expressed genes specifically leading to increased T (AKR1C3, 40 fold) or increased DHT levels (SRD5A1, 5.0 fold; 17BHSD10 4.8 fold; RLHSD, 99 fold). Downward triangles indicate highly differentially expressed genes specifically mediating DHT catabolism (AKR1C2, 7 fold; UGT2B15, 3000 fold).
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pone-0111545-g001: Characterization of LuCaP35 and LuCaP96 prostate cancer xenografts and responses to systemic androgen suppression.(A) Representative FFPE samples of each xenograft were stained with hematoxylin and eosin (H&E) and for expression of the androgen receptor (AR) and PSA as indicated. The scale bar (depicted on the PSA figures for ease of visualization) are 50µm. Kaplan-Meier plots of progression free survival (defined as tumor size <750 mm3) in mice bearing LuCaP35 (B) or LuCaP96 (C) xenografts. Intact male SCID mice were implanted subcutaneously with 30 mm3 pieces of the indicated xenografts. When tumors reached ∼300 mm3, mice were randomly enrolled into cohorts that were either left intact (No Cx) or castrated (Cx). P-values for curve comparisons were generated using the Mantel-Haenszel logrank test. (D) Mean and standard deviation of tissue testosterone (T, black bar) and DHT (gray bar) levels measured by mass spectrometry in tumors of the indicated xenograft (passaged in intact mice). (E) Relative expression of transcripts for the indicated steroidogenic genes was calculated using the delta dCt method (fold change = 2∧ddCt). Genes differentially expressed in LuCaP35 vs. LuCaP96 within one order of magnitude are indicated within the gray lines. Significant differences (by Welch’s t test; p<0.05) are indicated by black circles; white circles indicate genes that were not significantly different between LuCaP35 and LuCaP96 (all values given in Supplementary Data 2).Upward triangles indicate highly differentially expressed genes specifically leading to increased T (AKR1C3, 40 fold) or increased DHT levels (SRD5A1, 5.0 fold; 17BHSD10 4.8 fold; RLHSD, 99 fold). Downward triangles indicate highly differentially expressed genes specifically mediating DHT catabolism (AKR1C2, 7 fold; UGT2B15, 3000 fold).

Mentions: To evaluate tumor characteristics associated with response and resistance to AR pathway-directed therapy, we first determined intratumoral androgens and steroidogenic gene expression in two prostate cancer patient derived xenografts, LuCaP35 and LuCaP96. These lines express AR and PSA, (Figure 1A) and respond to castration with tumor regression and prolongation in progression-free survival (PFS), but ultimately progress to castration-resistant growth (p<0.0001 for both; Figure 1B, 1C). Notably, LuCaP35 and LuCaP96 tumors resected from mice with intact gonadal function exhibited marked differences in basal levels of intratumoral androgens (Figure 1D): LuCaP96 tumors have higher levels of T and similar levels of DHT, and thus a higher ratio of intratumoral T:DHT compared to LuCaP35 tumors, at 10∶1 and 2∶1, respectively (LuCaP96 T = 10.2±6.5 ng/gm; DHT = 0.9±0.4 ng/gm; LuCaP35 T = 2.6±2.0 ng/gm; DHT = 1.4±0.8 ng/gm, Table S1).


Prostate cancer characteristics associated with response to pre-receptor targeting of the androgen axis.

Mostaghel EA, Morgan A, Zhang X, Marck BT, Xia J, Hunter-Merrill R, Gulati R, Plymate S, Vessella RL, Corey E, Higano CS, Matsumoto AM, Montgomery RB, Nelson PS - PLoS ONE (2014)

Characterization of LuCaP35 and LuCaP96 prostate cancer xenografts and responses to systemic androgen suppression.(A) Representative FFPE samples of each xenograft were stained with hematoxylin and eosin (H&E) and for expression of the androgen receptor (AR) and PSA as indicated. The scale bar (depicted on the PSA figures for ease of visualization) are 50µm. Kaplan-Meier plots of progression free survival (defined as tumor size <750 mm3) in mice bearing LuCaP35 (B) or LuCaP96 (C) xenografts. Intact male SCID mice were implanted subcutaneously with 30 mm3 pieces of the indicated xenografts. When tumors reached ∼300 mm3, mice were randomly enrolled into cohorts that were either left intact (No Cx) or castrated (Cx). P-values for curve comparisons were generated using the Mantel-Haenszel logrank test. (D) Mean and standard deviation of tissue testosterone (T, black bar) and DHT (gray bar) levels measured by mass spectrometry in tumors of the indicated xenograft (passaged in intact mice). (E) Relative expression of transcripts for the indicated steroidogenic genes was calculated using the delta dCt method (fold change = 2∧ddCt). Genes differentially expressed in LuCaP35 vs. LuCaP96 within one order of magnitude are indicated within the gray lines. Significant differences (by Welch’s t test; p<0.05) are indicated by black circles; white circles indicate genes that were not significantly different between LuCaP35 and LuCaP96 (all values given in Supplementary Data 2).Upward triangles indicate highly differentially expressed genes specifically leading to increased T (AKR1C3, 40 fold) or increased DHT levels (SRD5A1, 5.0 fold; 17BHSD10 4.8 fold; RLHSD, 99 fold). Downward triangles indicate highly differentially expressed genes specifically mediating DHT catabolism (AKR1C2, 7 fold; UGT2B15, 3000 fold).
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4214744&req=5

pone-0111545-g001: Characterization of LuCaP35 and LuCaP96 prostate cancer xenografts and responses to systemic androgen suppression.(A) Representative FFPE samples of each xenograft were stained with hematoxylin and eosin (H&E) and for expression of the androgen receptor (AR) and PSA as indicated. The scale bar (depicted on the PSA figures for ease of visualization) are 50µm. Kaplan-Meier plots of progression free survival (defined as tumor size <750 mm3) in mice bearing LuCaP35 (B) or LuCaP96 (C) xenografts. Intact male SCID mice were implanted subcutaneously with 30 mm3 pieces of the indicated xenografts. When tumors reached ∼300 mm3, mice were randomly enrolled into cohorts that were either left intact (No Cx) or castrated (Cx). P-values for curve comparisons were generated using the Mantel-Haenszel logrank test. (D) Mean and standard deviation of tissue testosterone (T, black bar) and DHT (gray bar) levels measured by mass spectrometry in tumors of the indicated xenograft (passaged in intact mice). (E) Relative expression of transcripts for the indicated steroidogenic genes was calculated using the delta dCt method (fold change = 2∧ddCt). Genes differentially expressed in LuCaP35 vs. LuCaP96 within one order of magnitude are indicated within the gray lines. Significant differences (by Welch’s t test; p<0.05) are indicated by black circles; white circles indicate genes that were not significantly different between LuCaP35 and LuCaP96 (all values given in Supplementary Data 2).Upward triangles indicate highly differentially expressed genes specifically leading to increased T (AKR1C3, 40 fold) or increased DHT levels (SRD5A1, 5.0 fold; 17BHSD10 4.8 fold; RLHSD, 99 fold). Downward triangles indicate highly differentially expressed genes specifically mediating DHT catabolism (AKR1C2, 7 fold; UGT2B15, 3000 fold).
Mentions: To evaluate tumor characteristics associated with response and resistance to AR pathway-directed therapy, we first determined intratumoral androgens and steroidogenic gene expression in two prostate cancer patient derived xenografts, LuCaP35 and LuCaP96. These lines express AR and PSA, (Figure 1A) and respond to castration with tumor regression and prolongation in progression-free survival (PFS), but ultimately progress to castration-resistant growth (p<0.0001 for both; Figure 1B, 1C). Notably, LuCaP35 and LuCaP96 tumors resected from mice with intact gonadal function exhibited marked differences in basal levels of intratumoral androgens (Figure 1D): LuCaP96 tumors have higher levels of T and similar levels of DHT, and thus a higher ratio of intratumoral T:DHT compared to LuCaP35 tumors, at 10∶1 and 2∶1, respectively (LuCaP96 T = 10.2±6.5 ng/gm; DHT = 0.9±0.4 ng/gm; LuCaP35 T = 2.6±2.0 ng/gm; DHT = 1.4±0.8 ng/gm, Table S1).

Bottom Line: In LuCaP96 tumors (T:DHT 10:1), survival was not improved despite similar DHT reduction (0.02 ng/gm).Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression.Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and should be validated in additional models.

View Article: PubMed Central - PubMed

Affiliation: Division of Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America; Department of Medicine, University of Washington School of Medicine, Seattle, Washington, United States of America.

ABSTRACT

Background: Factors influencing differential responses of prostate tumors to androgen receptor (AR) axis-directed therapeutics are poorly understood, and predictors of treatment efficacy are needed. We hypothesized that the efficacy of inhibiting DHT ligand synthesis would associate with intra-tumoral androgen ratios indicative of relative dependence on DHT-mediated growth.

Methods: We characterized two androgen-sensitive prostate cancer xenograft models after androgen suppression by castration in combination with the SRD5A inhibitor, dutasteride, as well as a panel of castration resistant metastases obtained via rapid autopsy.

Results: In LuCaP35 tumors (intra-tumoral T:DHT ratio 2:1) dutasteride suppressed DHT to 0.02 ng/gm and prolonged survival vs. castration alone (337 vs.152 days, HR 2.8, p = 0.0015). In LuCaP96 tumors (T:DHT 10:1), survival was not improved despite similar DHT reduction (0.02 ng/gm). LuCaP35 demonstrated higher expression of steroid biosynthetic enzymes maintaining DHT levels (5-fold higher SRD5A1, 41 fold higher, 99-fold higher RL-HSD, p<0.0001 for both), reconstitution of intra-tumoral DHT (to ∼30% of untreated tumors), and ∼2 fold increased expression of full length AR. In contrast, LuCaP96 demonstrated higher levels of steroid catabolizing enzymes (6.9-fold higher AKR1C2, 3000-fold higher UGT2B15, p = 0.002 and p<0.0001 respectively), persistent suppression of intra-tumoral DHT, and 6-8 fold induction of full length AR and the ligand independent V7 AR splice variant. Human metastases demonstrated bio-active androgen levels and AR full length and AR splice-variant expression consistent with the range observed in xenografts.

Conclusions: Intrinsic differences in basal steroidogenesis, as well as variable expression of full length and splice-variant AR, associate with response and resistance to pre-receptor AR ligand suppression. Expression of steroidogenic enzymes and AR isoforms may serve as potential biomarkers of sensitivity to potent AR-axis inhibition and should be validated in additional models.

Show MeSH
Related in: MedlinePlus