Effective Prediction of Prostate Cancer Recurrence through the IQGAP1 Network

IQGAP1 expression was analyzed in: (1) primary prostate cancer, (2) xenografts produced from LNCaP, DU145, and PC3 cells, (3) tumor of PTEN−/− and TRAMP mice, and (4) castration resistant PC (CRPC) produced by LNCaP xenografts and PTEN−/− mice. IQGAP1 downregulations occurred in CRPC and advanced PCs. The downregulations were associated with rapid PC recurrence in the TCGA PanCancer (n = 492, p = 0.01) and MSKCC (n = 140, p = 4 × 10−6) cohorts. Differentially expressed genes (n = 598) relative to IQGAP1 downregulation were identified with enrichment in chemotaxis, cytokine signaling, and others along with reductions in immune responses. A novel 27-gene signature (Sig27gene) was constructed from these DEGs through random division of the TCGA cohort into a Training and Testing population. The panel was validated using an independent MSKCC cohort. Sig27gene robustly predicts PC recurrence at (hazard ratio) HR 2.72 and p < 2 × 10−16 in two independent PC cohorts. The prediction remains significant after adjusting for multiple clinical features. The novel and robust nature of Sig27gene underlie its great translational potential as a prognostic biomarker to predict PC relapse risk in patients with primary PC.

rAAV-Delivered PTEN Therapeutics for Prostate Cancer

Background: Prostate cancer (PCa) is the second most popular diagnosed cancer and the fifth leading cause of cancer-related mortality for males globally. At present, effective treatments for PCa need to be further developed. To further understand the molecular mechanism and develop novel therapeutics for PCa, the role of phosphatase and tensin homolog (PTEN) signaling in PCa progression was investigated. Previous studies have reported that PTEN and its downstream target cyclin-dependent kinase inhibitor 1B (CDKN1B) are significantly downregulated in PCa cells compared to normal controls; therefore, modulation of PTEN and CDKN1B expression might be a promising therapeutic approach for PCa treatment. Methods: The expression of PTEN and CDKN1B was first verified in specimens from PCa patients or transgenic adenocarcinoma mouse prostate (TRAMP) mice. The effect of PTEN on PCa cell migration, apoptosis and cell cycle was analyzed by wound healing assay and flow cytometry in vitro. Next, we tested the concept of intraprostatic and intratumoral injection of recombinant adeno-associated virus (rAAV) 9 expressing Pten or Cdkn1b (4x1011 genome copies (GCs)/prostate) into 8-week-old TRAMP mice and a subcutaneous tumor xenograft mouse model (5x1011 GCs/tumor), respectively, to inhibit PCa progression. Results: PTEN and CDKN1B were significantly downregulated in human and mouse PCa samples, and CDKN1B expression was positively correlated with PTEN expression. Further, PTEN overexpression significantly inhibited the cell migration and cell cycle progression and promoted the apoptosis of PCa cells by decreasing Ccnd1 expression and increasing Cdkn1b expression. Importantly, rAAV9.Pten or rAAV9.Cdkn1b treatment significantly extended the lifespan of TRAMP mice and inhibited the growth rate of tumor xenografts by regulating downstream gene expression. Moreover, we confirmed that neoplasia in the treated prostates was significantly diminished compared to that in the control prostates and that apoptosis was markedly observed in xenografts treated with Pten or Cdkn1b, highlighting changes in two crucial factors for PCa progression. Conclusions: Taken together, these data indicate that rAAV-based PTEN/CDKN1B delivery holds promise for the development of novel therapeutics for PCa.

Impact of Vasectomy on the Development and Progression of Prostate Cancer: Preclinical Evidence

Some observational studies have implied a link between vasectomy and an elevated risk of prostate cancer. We investigated the impact of vasectomy on prostate cancer outgrowth, mainly using preclinical models. Neoplastic changes in the prostate were compared in transgenic TRAMP mice that underwent vasectomy vs. sham surgery performed at 4 weeks of age. One of the molecules identified by DNA microarray (i.e., ZKSCAN3) was then assessed in radical prostatectomy specimens and human prostate cancer lines. At 24 weeks, gross tumor (p = 0.089) and poorly differentiated adenocarcinoma (p = 0.036) occurred more often in vasectomized mice. Vasectomy significantly induced ZKSCAN3 expression in prostate tissues from C57BL/6 mice and prostate cancers from TRAMP mice. Immunohistochemistry showed increased ZKSCAN3 expression in adenocarcinoma vs. prostatic intraepithelial neoplasia (PIN), PIN vs. non-neoplastic prostate, Grade Group ≥3 vs. ≤2 tumors, pT3 vs. pT2 tumors, pN1 vs. pN0 tumors, and prostate cancer from patients with a history of vasectomy. Additionally, strong (2+/3+) ZKSCAN3 expression (p = 0.002), as an independent prognosticator, or vasectomy (p = 0.072) was associated with the risk of tumor recurrence. In prostate cancer lines, ZKSCAN3 silencing resulted in significant decreases in cell proliferation/migration/invasion. These findings suggest that there might be an association between vasectomy and the development and progression of prostate cancer, with up-regulation of ZKSCAN3 expression as a potential underlying mechanism.

Impact of Dietary Tomato on Prostate Carcinogenesis and Progression in Lean and Overweight/Obese TRAMP Mice

Objectives The primary objective was to determine the effect of dietary tomato on prostate cancer (PCa) development and progression in overweight/obese, transgenic mice prone to PCa (TRAMP mice). Secondary objectives included assessing histological, inflammatory, angiogenic, and metabolic changes in prostate tumors at different time points of cancer progression. Methods Four-week-old TRAMP mice were randomly assigned to consume one of four diets (n = 45/diet): control (CON) or obesogenic (OB), both with and without 10% freeze-dried tomato powder (TP). Prostate tumor incidence and growth were monitored via ultrasound imaging. Mice were terminated one or four weeks following tumor development to assess early and later molecular changes in the tumors. Results OB diets led to greater body weight over time (45.2 ± 1.0 g at 24 weeks of age) when compared with CON diets (33.2 ± 0.8 g; p &lt; 0.0001 by 2-way ANOVA), with TP inclusion having no impact on body weight within diets. OB diets resulted in greater tumor incidence (64.8% vs. 42.5%), earlier age at tumor onset (16.9 ± 1.0 weeks vs. 18.6 ± 0.7 weeks), higher body weight at tumor detection (38.6 ± 1.0 g vs. 30.8 ± 1.2 g), and greater post-mortem periprostatic adipose weight (2.0 ± 0.1 g vs. 0.9 ± 0.1 g). TP intake was protective only in lean animals, with CON-TP-fed animals having exhibited lower tumor volume at detection (28.7 ± 5.2 mm3 vs. 47.3 ± 15.5 mm3) and lower tumor weight at both one (0.1 ± 0.02 g vs. 0.2 ± 0.06 g) and four (1.5 ± 0.3 g vs. 2.1 ± 0.5 g) weeks following tumor detection compared with CON-fed animals. Conversely, TP was not protective in animals with obesity, with OB-TP-fed animals having exhibited no differences in tumor weight one week following tumor detection (0.3 ± 0.06 g vs. 0.3 ± 0.07 g) and greater tumor weight four weeks following tumor detection (2.5 ± 0.7 g vs. 2.0 ± 0.3 g) when compared with OB-fed animals. Conclusions TRAMP mice fed obesogenic diets have higher body weight and earlier onset of PCa. While tomato intake led to smaller tumors in lean animals, the opposite effect was observed in animals with higher body weight. Funding Sources This research is supported by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health.

Dietary Tomato Varieties Similarly Inhibit Prostate Carcinogenesis in the TRAMP Model in Association with Distinct Transcriptomic and Metabolomic Profiles

Objectives Lycopene intake is associated with reduced risk of prostate cancer, especially lethal disease. Tangerine tomatoes contain highly bioavailable lycopene isomers, compared to red tomatoes, but impact of isomers on cancer preventive bioactivity are unknown. Our goals are: (1) to determine if feeding tomato containing diets with differing lycopene isomers inhibit transgenic adenocarcinoma of the mouse prostate (TRAMP) carcinogenesis, and (2) to determine key early metabolic and transcriptional pathways through which tomatoes act to prevent carcinogenesis. Methods We examine prostate carcinogenesis in the TRAMP model, comparing two tomatoes with distinct lycopene isomer profiles: all-trans-lycopene-rich red tomatoes and cis-lycopene-isomer-rich tangerine tomatoes. Weanling TRAMP and wild type (WT) mice were fed AIN-93 G control, 10% tangerine tomato + AIN-93 G (w/w), or 10% red tomato + AIN-93 G (w/w) diet until 10 or 18 wks. At 10 wks., prostate RNA-seq and plasma metabolomics were performed on TRAMP and WT samples. At 18 wks., plasma carotenoid analysis and histopathology was performed on TRAMP mice. Results At 18 wks., plasma lycopene concentrations were 2.84-fold greater in tangerine tomato-fed mice than red tomato-fed mice (p &lt; 0.0001), yet both red and tangerine tomato diets similarly prevent carcinoma incidence compared to the control diet by 43% and 36% respectively (p &lt; 0.001, both vs. control). Our investigation of early carcinogenesis (10 wks.) shows that both tomato diets similarly impact the plasma metabolome, and we define prostate transcriptomic profiles mediated by TRAMP genotype, such as inflammation- and immune-regulated pathways, that are inhibited by dietary tomato. We identify an inflammatory gene panel (Olr1, Il1a, Cscl9, and Ccl22) which is inhibited by tomato diets. In a human prostate cancer database, higher expression of this gene panel is associated with a more aggressive phenotype. Conclusions Together, our results implicate red and tangerine tomatoes as potentially beneficial for the inhibition of early prostate carcinogenesis through the modulation of transcriptional programs centered on inflammation and the immune response. Our findings support efforts to test novel tomato products for the inhibition of human prostate carcinogenesis. Funding Sources AICR, NIH P30, USDA NNF.

Dietary Tomato or Lycopene Do Not Reduce Castration-Resistant Prostate Cancer Progression in a Murine Model

ABSTRACT Background Dietary tomato products or lycopene protect against prostate carcinogenesis, but their impact on the emergence of castration-resistant prostate cancer (CRPC) is unknown. Objective We hypothesized that tomato or lycopene products would reduce the emergence of CRPC. Methods Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were castrated at 12–13 wk and the emergence of CRPC was monitored by ultrasound in each study. In Study 1, TRAMP mice (n = 80) were weaned onto an AIN-93G-based control diet (Con-L, n = 28), a 10% tomato powder diet (TP-L, 10% lyophilized w/w, n = 26), or a control diet followed by a tomato powder diet after castration (TP-Int1, n = 26). In Study 2, TRAMP mice (n = 85) were randomized onto a control diet with placebo beadlets (Con-Int, n = 29), a tomato diet with placebo beadlets (TP-Int2, n = 29), or a control diet with lycopene beadlets (Lyc-Int, n = 27) following castration (aged 12 wk). Tumor incidence and growth were monitored by ultrasound beginning at an age of 10 wk. Mice were euthanized 4 wk after tumor detection or aged 30 wk if no tumor was detected. Tissue weights were compared by ANOVA followed by Dunnett's test. Tumor volumes were compared using generalized linear mixed model regression. Results Ultrasound estimates for the in vivo tumor volume were strongly correlated with tumor weight at necropsy (R2 = 0.75 and 0.94, P &lt;0.001 for both Studies 1 and 2, respectively). Dietary treatments after castration did not significantly impact cancer incidence, time to tumor detection, or final tumor weight. Conclusions In contrast to studies of de novo carcinogenesis in multiple preclinical models, tomato components had no significant impact on the emergence of CRPC in the TRAMP model. It is possible that specific mutant subclones of prostate cancer may continue to show some antiproliferative response to tomato components, but further studies are needed to confirm this.