Michael J. Schlicht

Effect of Soy Protein Isolate Supplementation on Biochemical Recurrence of Prostate Cancer After Radical Prostatectomy: A Randomized Trial

IMPORTANCE Soy consumption has been suggested to reduce risk or recurrence of prostate cancer, but this has not been tested in a randomized trial with prostate cancer as the end point. OBJECTIVE To determine whether daily consumption of a soy protein isolate supplement for 2 years reduces the rate of biochemical recurrence of prostate cancer after radical prostatectomy or delays such recurrence. DESIGN, SETTING, AND PARTICIPANTS Randomized, double-blind trial conducted from July 1997 to May 2010 at 7 US centers comparing daily consumption of a soy protein supplement vs placebo in 177 men at high risk of recurrence after radical prostatectomy for prostate cancer. Supplement intervention was started within 4 months after surgery and continued for up to 2 years, with prostate-specific antigen (PSA) measurements made at 2-month intervals in the first year and every 3 months thereafter. INTERVENTION Participants were randomized to receive a daily serving of a beverage powder containing 20 g of protein in the form of either soy protein isolate (n=87) or, as placebo, calcium caseinate (n=90). MAIN OUTCOMES AND MEASURES Biochemical recurrence rate of prostate cancer (defined as development of a PSA level of ≥0.07 ng/mL) over the first 2 years following randomization and time to recurrence. RESULTS The trial was stopped early for lack of treatment effects at a planned interim analysis with 81 evaluable participants in the intervention group and 78 in the placebo group. Overall, 28.3% of participants developed biochemical recurrence within 2 years of entering the trial (close to the a priori predicted recurrence rate of 30%). Among these, 22 (27.2%) occurred in the intervention group and 23 (29.5%) in the placebo group. The resulting hazard ratio for active treatment was 0.96 (95% CI, 0.53-1.72; log-rank P = .89). Adherence was greater than 90% and there were no apparent adverse events related to supplementation. CONCLUSION AND RELEVANCE Daily consumption of a beverage powder supplement containing soy protein isolate for 2 years following radical prostatectomy did not reduce biochemical recurrence of prostate cancer in men at high risk of PSA failure. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00765479.

L-Selenomethionine Does Not Protect Against Testosterone Plus 17β-Estradiol-Induced Oxidative Stress and Preneoplastic Lesions in the Prostate of NBL Rats

Previous animal studies examining dietary selenium effects on prostatic carcinogenesis did not show preventive benefit, including 1 study in a rat model involving testosterone (T) and estradiol (E2)-induced prostatic oxidative stress. Here, we examined modulation of T + E2-induced prostatic oxidative stress, dysplasia, and inflammation by L-selenomethionine at 1.5 or 3.0 mg selenium/kg in NIH-07 diet in Noble (Nbl)/Crl rats treated with T + E2 for 16 wk. Hormone treatment increased immunohistochemical staining for 8-hydroxydeoxyguanosine (8-OHdG) in the prostatic sites of T + E2-induced preneoplasia (P < 0.05), but selenomethionine did not attenuate 8-OHdG staining and dysplasia in the lateral prostate. Glutathione-peroxidase activity (P < 0.05) and mRNA expression were induced by T + E2 (P < 0.0001) but not changed by selenomethionine. Selenomethionine did not cause significant responses in expression and activity of glutathione-peroxidase and MnSOD, except for a reduction of MnSOD protein expression in the lateral prostate (P < 0.01). The absence of reduction of oxidative stress and dysplasia and the minimal effects on antioxidant enzymes caused by selenomethionine are consistent with the null effects observed in selenium supplementation animal studies and clinical trials. Significant (P < 0.01) opposite apoptosis/cell proliferation balance responses to selenomethionine and to T + E2 occurred in the lateral and dorsal prostate, explaining why T + E2 induces lesions selectively in the lateral lobe of NBL rats.

Flaxseed Suppressed Prostatic Epithelial Proliferation in a Rat Model of Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH), a disease occurring frequently among elderly males, is a slow progressive enlargement of the fibromuscular and epithelial structures of the prostate gland. Dietary factors may influence the prostate and exert an influence on prostatic growth and disease. The current study was undertaken to investigate the protective effect of dietary flaxseed supplementation against testosterone-induced prostatic hyperplasia in male rats. Forty male Wistar rats were divided into 5 groups: (1) untreated control; (2) treatment with testosterone propionate (TP) to induce prostate enlargement; (3) TP-treated group fed a diet containing 5% milled flaxseed; (4) TP-treated group fed a diet containing 10% milled flaxseed; and (5) TP-treated group fed a diet containing 20 ppm finasteride. Treatment with TP significantly increased the absolute and relative weights of different prostatic lobes, serum testosterone (T), and testosterone/estradiol ratio, as well as prostatic vascular endothelial growth factor (VEGF) expression, RNA synthesis per cell, and epithelial cell proliferation, detected as Ki67 labeling. Histopathological examination did not reveal marked differences in acinar morphology in ventral prostate, whereas morphometric analysis showed significantly increased epithelial cell height. Co-administration of flaxseed or finasteride with TP significantly reduced prostatic VEFG, epithelial cell proliferation, and RNA/DNA ratio, along with a significant increase in serum T and testosterone/estradiol ratio compared with TP-only-treated rats. Our results indicate that flaxseed, similar to the 5α-reductase inhibitor finasteride, blocked TP-induced prostate enlargement in a rat model of BPH, likely through suppression of prostatic VEFG and cellular proliferation.

Abstract 4322: Iron increases the invasiveness of prostate cancer cells in vitro: Mechanisms and inhibition by the antioxidant ebselen

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL The effect of iron on PC-3 prostate cancer cell invasiveness was investigated using Neuroprobe filter membrane transmigration assays. PC-3 cells were pre-incubated with ferric ammonium citrate (FAC) for 6 hours. Excess iron was removed before the assay. The PC-3 cells were placed on an extracellular membrane preparation (Matrigel®) in the upper wells of the chamber and allowed to migrate onto the underside of a porous membrane that allowed cell transmigration. The number of cells migrating to the underside of the membrane was determined and used as a marker of cell invasion. Pre-treatment with 100 µM FAC caused a 4-fold increase in PC-3 cell invasion when measured at 24 hours (P< 0.05). The FAC concentrations that induced PC-3 invasion were 100 times smaller than concentrations which interfered with cell viability or proliferation rate. Western blot analysis suggested that the effect of FAC exposure on PC-3 cell invasion was mediated by p42/44 MAP kinase activity. Furthermore, the antioxidant ebselen, a hydrogen peroxide inhibitor, decreased FAC-induced PC-3 cell invasion. We also examined the mRNA expression of invasion-related genes using a cDNA array and found a positive correlation between the exposures to FAC and the invasion phenotype of prostate cancer cells. The data demonstrated that the upregulation of genes, such as fractalkine and plasminogen, after FAC treatment may be associated with iron-induced invasion of prostate cancer. Our data suggest that iron overload may be detrimental to patients with prostate cancer and that the effect of iron on invasion may be inhibited by ebselen. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4322. doi:1538-7445.AM2012-4322

A novel L-asparaginase with low L-glutaminase coactivity is highly efficacious against both T and B cell acute lymphoblastic leukemias in vivo

Acute lymphoblastic leukemia (ALL) is the most common type of pediatric cancer, although about 4 of every 10 cases occur in adults. The enzyme drug l-asparaginase serves as a cornerstone of ALL therapy and exploits the asparagine dependency of ALL cells. In addition to hydrolyzing the amino acid l-asparagine, all FDA-approved l-asparaginases also have significant l-glutaminase coactivity. Since several reports suggest that l-glutamine depletion correlates with many of the side effects of these drugs, enzyme variants with reduced l-glutaminase coactivity might be clinically beneficial if their antileukemic activity would be preserved. Here we show that novel low l-glutaminase variants developed on the backbone of the FDA-approved Erwinia chrysanthemi l-asparaginase were highly efficacious against both T- and B-cell ALL, while displaying reduced acute toxicity features. These results support the development of a new generation of safer l-asparaginases without l-glutaminase activity for the treatment of human ALL.Significance: A new l-asparaginase-based therapy is less toxic compared with FDA-approved high l-glutaminase enzymes Cancer Res; 78(6); 1549-60. ©2018 AACR.

Abstract 2131: Effects of black raspberries and their constituents on rat prostate carcinogenesis and human prostate cancer cell growth

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Black raspberries (BRBs) and their constituents may inhibit human GI tract cancers and prevent breast cancer in a rat model. Anthocyanins and polyphenols in BRBs are responsible for their anti-cancer effects. Berries and other fruits are used as dietary supplements by cancer patients. As prostate cancer remains a major health problem, it is thus important to determine whether BRBs or BRB constituents may prevent or treat this malignancy. We previously reported (AACR Ann Mtg 2013) that the BRB anthocyanin metabolite protocatechuic acid (PCA) was detectable in the prostate of rats fed BRB, indicating that it reaches this tissue, but BRB consumption by Wistar rats did not prevent prostate cancer induced by MNU and chronic testosterone treatment. We now studied the effect of feeding AIN-93M diet containing 5% or 10% lyophilized BRB powder (exchanged for starch) on induction of prostate cancer in NBL rats by chronic testosterone & 17β-estradiol treatment via SC Silastic implants. Incidence of adenocarcinomas arising from periurethral prostatic ducts was similar in rats fed control diet and those fed berry-containing diets (73-90%), as was tumor multiplicity (1.7-1.8 tumors per prostate). In contrast, we previously found that cyanidin-3-rutinoside, the most abundant anthocyanin in BRBs, inhibits growth of LAPC-4 human prostate cancer cells. We now used PC-3 and LNCaP prostate cancer cells to study effects of ethanolic extract of lyophilized BRB powder and major BRB constituents: the polyphenol ellagic acid (EA), cyanidin-3-rutinoside, and PCA. Growth rates were measured by hemocytometer counting with trypan blue exclusion. BRB extract (1 µg/ml to 1 mg/ml) inhibited viability of LNCaP cells dose-dependently, but linear trend was not significant (p=0.09). Similar, but also not quite significant, decreases in LNCaP cell numbers were caused by PCA and EA, while EA increased the number of dead cells (ANOVA p=0.0471, linear trend p=0.0385). No significant changes occurred in PC-3 cell viability with any of the treatments. Effects on anchorage independent growth of PC-3 cells were assessed by soft agar colony forming assays. A dose-dependent reduction in the number of colonies occurred after EA treatment (ANOVA p=0.0065, linear trend p=0.0007) and BRB extract (ANOVA p<0.0001, linear trend p<0.0001), but no change in colony formation of cells treated with cyanidin-3-rutinoside or PCA. Compared to vehicle, BRB at 1 mg/ml maximally reduced colonies by 50%, and 3.0 µg/ml EA reduced colonies by 39%. No effects on cell migration of PC-3 cells, assessed by wound healing assays, were found for any of the treatments. Thus, BRBs may be beneficial for treatment of prostate cancer and EA is at least partially responsible for the anti-cancer activity of BRBs, but, surprisingly, cyanidin-3-rutinoside and protocatechuic acid did not have significant effects. (Supported by NIH Grant R21 CA152879). Citation Format: Jillian N. Eskra, Michael J. Schlicht, Maarten C. Bosland. Effects of black raspberries and their constituents on rat prostate carcinogenesis and human prostate cancer cell growth. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2131. doi:10.1158/1538-7445.AM2014-2131

Lack of combination effects of soy isoflavones and taxane chemotherapy of castration-resistant prostate cancer

Patients with cancer, including prostate cancer, often use dietary supplements, such as soy or isoflavones, before, during, or after therapy. There is little information about possible interactions between supplements and cancer chemotherapy. There are some reports suggesting enhancement by genistein of taxane chemotherapy for castrate‐resistant prostate cancer (CRPC).

Abstract 2892: Effects of soy protein isolate consumption on serum steroid hormones and biomarkers of angiogenesis, apoptosis, and the IGF axis in men after radical prostatectomy

Epidemiologic and experimental data suggest that soy may prevent prostate cancer and be beneficial for men with prostate cancer. The mechanisms by which soy may be protective are unclear. Effects of soy constituents on steroid hormones and on angiogenesis, apoptosis, and the insulin growth factor [IGF] axis may be involved. This was examined in a randomized controlled clinical trial testing whether soy reduces biochemical recurrence after radical prostatectomy. Men at high risk for PSA failure after surgery were randomized to a daily soy protein supplement or a casein-based placebo (20 g protein/day) as beverage powders (Solae). The soy and placeboi supplements were identical in composition, except for the protein source. The soy supplement provided 24-26 mg genistein and 40-43 mg total isoflavones daily. The placebo did not contain these or other soy-specific constituents. Self-reported compliance was excellent, serum isoflavones are measured as independent compliance measure, and only few minimal averse effects occurred. Serum samples were taken at baseline, and after 2, 4, 8, 12, and 18 months on intervention. Using ELISA and enzyme immuno-assays, we measured serum indicators of angiogenesis (VEGF and bFGF), global apoptotic activity (soluble Fas [sFas] and Fas ligand [FasL]) and the IGF axis (IGF-1 and IGF binding protein 3 [IGFBP3]) in 8-12 subjects/treatment group, and serum testosterone [T], 17β-estradiol [E2], sex hormone binding globulin [SHBG], and PSA in 12 subjects/group. Generalized Estimating Equations were used to analyze the longitudinal data. FasL increased slightly over time in the placebo group (p=0.05), but sFas did not and there were no differences in change over time between the groups for either. IGF-1 increased slightly over time in placebos (p=0.06), but IGFBP3 did not and there were no differences in change over time between the groups for these endpoints. In contrast, while T levels did not change over time in the placebo group, T levels decreased significantly (p=0.03) from baseline over time by approx. 15% in the soy group. There were no diffrence over time in E2 and SHBG levels in either group. While literature data indicate a lack of soy effects on T and SHBG, this is the first report of soy effects on circulating T and SHBG with repeated serum sampling for up to 1.5 years. This is also the first report of soy effects on serum VEGF, bFGF, sFas, and FasL. The absence of effects on the IGF axis is in line with other studies. Thus, daily consumption of 20 g of soy protein isolate for 18 months slightly reduced serum T levels over time, but did not affect E2, SHBG, and indicators of angiogenesis, apoptosis, and the IGF axis. Despite small sample sizes, several of the group comparisons were close to statistical significance, providing some direction for further studies. (Supported by CA27790 & CA166195 from NIH and the Prevent Cancer Foundation) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2892.