Diallyl Trisulfide Inhibits Leptin-induced Oncogenic Signaling in Human Breast Cancer Cells but Fails to Prevent Chemically-induced Luminal-type Cancer in Rats

Previous studies have demonstrated inhibitory effect of garlic component diallyl trisulfide (DATS) on growth of breast cancer cells in vitro and in vivo. This study investigated the effect of DATS on oncogenic signaling regulated by leptin, which plays an important role in breast carcinogenesis. Leptin-induced phosphorylation and nuclear translocation of STAT3 was inhibited significantly in the presence of DATS in MCF-7 (a luminal-type human breast cancer cell line) and MDA-MB-231 (a basal-like human breast cancer cell line). Leptin-stimulated cell proliferation, clonogenic cell survival, and migration and/or invasion ability in MCF-7 and/or MDA-MB-231 cells were also suppressed by DATS treatment. DATS exposure resulted in inhibition of leptin-stimulated expression of protein and/or mRNA levels of Bcl-2, Bcl-xL, Cyclin D1, vascular endothelial growth factor, and matrix metalloproteinase-2. Western blotting revealed a decrease in protein levels of phosphorylated STAT3 in breast cancer xenografts from DATS-treated mice when compared to controls in vivo. However, the incidence of N-methyl-N-nitrosourea-induced luminal-type breast cancer development in rats was not affected by oral administration of 5 mg/kg or 25 mg/kg DATS. The present study reveals that oncogenic signaling induced by leptin is inhibited in the presence of DATS but higher doses of this phytochemical may be required to achieve chemopreventive activity.

Withania somnifera root extract inhibits fatty acid synthesis in prostate cancer cells

Prior research argues for a role of increased de novo fatty acid synthesis in pathogenesis of prostate adenocarcinoma, which remains a leading cause of cancer-associated mortality in American men. A safe and effective inhibitor of fatty acid synthesis is still a clinically unmet need. Herein, we investigated the effect of ethanol extract of Withania somnifera root (WRE) standardized for one of its components (withaferin A) on fatty acid synthesis using LNCaP and 22Rv1 human prostate cancer cells. Withania somnifera is a medicinal plant used in the Ayurvedic medicine practiced in India. Western blotting and confocal microscopy revealed a statistically significant decrease in protein levels of key fatty acid metabolism enzymes including ATP citrate lyase (ACLY), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FASN), and carnitine palmitoyltransferase 1A (CPT1A) in WRE-treated cells compared with solvent control. The mRNA levels of ACLY, ACC1, FASN, and CPT1A were also lower in WRE-treated cells in comparison with control. Consequently, WRE treatment resulted in a significant decrease in intracellular levels of acetyl-CoA, total free fatty acids, and neutral lipid droplets in both LNCaP and 22Rv1 cells. WRE exhibited greater potency for fatty acid synthesis inhibition at equimolar concentration than cerulenin and etomoxir. Exposure to WRE results in downregulation of c-Myc and p-Akt(S473) proteins in 22Rv1 cell line. However, overexpression of only c-Myc conferred protection against clonogenic cell survival and lipogenesis inhibition by WRE. In conclusion, these results indicate that WRE is a novel inhibitor of fatty acid synthesis in human prostate cancer cells.

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Withania somnifera is a medicinal plant used in alternative medicine (Ayurvedic medicine) system practiced in India.

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Withania somnifera root extract exhibits a variety of pharmacological effects including anticancer activity.

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The present study reveals that Withania somnifera root extract is a potent inhibitor of lipogenesis in prostate cancer cells.

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Inhibition of lipogenesis seems to be a useful biomarker of anticancer efficacy of Withania somnifera in prostate cancer.

A Novel Sulforaphane-Regulated Gene Network in Suppression of Breast Cancer-Induced Osteolytic Bone Resorption

Bone is the most preferred site for colonization of metastatic breast cancer cells for each subtype of the disease. The standard of therapeutic care for breast cancer patients with bone metastasis includes bisphosphonates (e.g., zoledronic acid), which have poor oral bioavailability, and a humanized antibody (denosumab). However, these therapies are palliative, and a subset of patients still develop new bone lesions and/or experience serious adverse effects. Therefore, a safe and orally bioavailable intervention for therapy of osteolytic bone resorption is still a clinically unmet need. This study demonstrates suppression of breast cancer-induced bone resorption by a small molecule (sulforaphane, SFN) that is safe clinically and orally bioavailable. In vitro osteoclast differentiation was inhibited in a dose-dependent manner upon addition of conditioned media from SFN-treated breast cancer cells representative of different subtypes. Targeted microarrays coupled with interrogation of The Cancer Genome Atlas data set revealed a novel SFN-regulated gene signature involving cross-regulation of runt-related transcription factor 2 (RUNX2) and nuclear factor-κB and their downstream effectors. Both RUNX2 and p65/p50 expression were higher in human breast cancer tissues compared with normal mammary tissues. RUNX2 was recruited at the promotor of NFKB1 Inhibition of osteoclast differentiation by SFN was augmented by doxycycline-inducible stable knockdown of RUNX2. Oral SFN administration significantly increased the percentage of bone volume/total volume of affected bones in the intracardiac MDA-MB-231-Luc model indicating in vivo suppression of osteolytic bone resorption by SFN. These results indicate that SFN is a novel inhibitor of breast cancer-induced osteolytic bone resorption in vitro and in vivo.

Withaferin A inhibits expression of ataxia telangiectasia and Rad3-related kinase and enhances sensitivity of human breast cancer cells to cisplatin

Ataxia telangiectasia and Rad3-related (ATR) is a serine/threonine-specific kinase that plays an important role in the maintenance of genomic integrity. In this study, we investigated the role of ATR in cell-cycle arrest by withaferin A (WA), a cancer preventative steroidal lactone derived from Withania somnifera plant abundant in India and surrounding countries. The WA treatment decreased the viability of MCF-7, MDA-MB-231, and SUM159 cells. Exposure of breast cancer cells to WA also resulted in suppression of protein level as well as phosphorylation of ATR and its downstream effector kinase (checkpoint kinase 1; CHK1). Both transcriptional and posttranscriptional mechanisms were involved in the WA-mediated downregulation of ATR protein. Downregulation of ATR protein expression resulting from WA exposure was not attenuated by overexpression of manganese superoxide dismutase. In contrast, the overexpression of CHK1 attenuated WA-mediated G₂ /M arrest and augmented S10 phosphorylation of histone H3, a marker of mitotic arrest. The protein level of ATR was lowered by about 50% in breast tumors of WA-treated mouse mammary tumor virus-neu mice when compared with vehicle-treated controls but the difference was not significant due to small sample size. WA treatment sensitized MDA-MB-231 and SUM159 cells to growth inhibition and apoptosis induction by cisplatin. Cisplatin treatment resulted in increased autophosphorylation of ATR (T1989) and CHK1 (S345) phosphorylation that was markedly suppressed in the presence of WA. These results indicate that WA is an inhibitor of ATR in human breast cancer cells.

Leelamine Is a Novel Lipogenesis Inhibitor in Prostate Cancer Cells In Vitro and In Vivo

Increased de novo synthesis of fatty acids is implicated in the pathogenesis of human prostate cancer, but a safe and effective clinical inhibitor of this metabolic pathway is still lacking. We have shown previously that leelamine (LLM) suppresses transcriptional activity of androgen receptor, which is known to regulate fatty acid synthesis. Therefore, the current study was designed to investigate the effect of LLM on fatty acid synthesis. Exposure of 22Rv1, LNCaP, and PC-3 prostate cancer cells, but not RWPE-1 normal prostate epithelial cell line, to LLM resulted in a decrease in intracellular levels of neutral lipids or total free fatty acids. LLM was superior to another fatty acid synthesis inhibitor (cerulenin) for suppression of total free fatty acid levels. LLM treatment downregulated protein and/or mRNA expression of key fatty acid synthesis enzymes, including ATP citrate lyase, acetyl-CoA carboxylase 1, fatty acid synthase, and sterol regulatory element-binding protein 1 (SREBP1) in each cell line. Consistent with these in vitro findings, we also observed a significant decrease in ATP citrate lyase and SREBP1 protein expression as well as number of neutral lipid droplets in vivo in 22Rv1 tumor sections of LLM-treated mice when compared with that of controls. LLM-mediated suppression of intracellular levels of total free fatty acids and neutral lipids was partly attenuated by overexpression of SREBP1. In conclusion, these results indicate that LLM is a novel inhibitor of SREBP1-regulated fatty acid/lipid synthesis in prostate cancer cells that is not affected by androgen receptor status.

Scrotal infrared thermography and testicular biometry: Indicator of semen quality in Murrah buffalo bulls

This aim of this study was to assess the relationship, if any, of scrotal surface temperature gradient (SSTG), scrotal circumference (SC) and testicular covering thickness (TCT) with semen quality in Murrah buffalo breeding bulls. For this, buffalo breeding bulls (n = 130) were selected from four different semen centres. The ejaculates of each bull were evaluated for ejaculate volume (EV), mass motility (MM); concentration (SPC), motility (SM), viability and abnormalities (SA). The SSTG, SC and TCT of individual bulls were quantified using digital infrared thermography, measuring tape and ultrasonography, respectively. The bulls were divided into three groups on the basis of SSTG (≤ 4 °C, 4.1 to 6.4 °C and ≥ 6.5 °C), and SC (<31, 31 to 35 and> 35 cm) and into two groups on the basis of TCT (5 to 7.2 and 7.4 to 10.4 mm). Results indicated the bulls with a larger temperature gradient and larger SC produced greater quality semen than those with a lesser temperature gradient. The MM (P < 0.01) and SPC (P < 0.05) varied among the groups along with SSTG. Among the SC groups the EV, MM, SPC and SM (P < 0.01), and viability (P < 0.05) varied as did the SC. The bulls with a lesser TCT had a lesser SA (P < 0.05) as compared to the group with the greater TCT. Buffalo bulls having a greater SSTG, SC and lesser TCT produced semen of greater quality and these variables may be used as criteria for breeding soundness evaluation.

Abstract 5081: Leelamine is a novel inhibitor of fatty acid synthesis in prostate cancer

Increased beta-oxidation of fatty acids to meet energy demand is a rather unique characteristic of a subset of human prostate cancers. A safe and effective intervention for inhibition of fatty acid synthesis is still a clinically unmet need. We have shown previously that leelamine (LLM), a phytochemical derived from pine tree bark, suppresses expression and activity of full-length androgen receptor (AR) and its splice variants in vitro and in vivo in preclinical models of prostate cancer. Because AR is implicated in regulation of fatty acid metabolism, the present study was undertaken to determine the effect of LLM on this metabolic pathway. Treatment of a castration-resistant (22Rv1) as well as an androgen-responsive (LNCaP) human prostate cancer cell line with LLM (2.5 and 5 µmol/L) resulted in downregulation of key fatty acid synthesis enzyme proteins including ATP citrate lyase (ACLY), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FASN), and sterol regulatory element-binding protein 1 (SREBP1). LLM treatment also decreased intracellular levels of total free fatty acids and neutral lipid droplets in LNCaP and 22Rv1 cells. Consistent with the in vitro results, we also observed a significant decrease in ACLY and SREBP1 protein expression and number of neutral lipid droplets in vivo in tumor tissue sections of 22Rv1 xenografts after intraperitoneal administration of LLM (9.1 mg/kg bw/ day, 5 times/week) compared to controls. Studies are in progress to determine if overexpression of AR and/or SREBP1 confers protection against fatty acid synthesis inhibition by LLM. In conclusion, it is reasonable to postulate that suppression of AR-SREBP1 regulated fatty acid metabolism is an important mechanism in prostate cancer inhibition by LLM. This study was supported by the grant RO1 CA101753 awarded by the National Cancer Institute.

Citation Format: Krishna B. Singh, Shivendra V. Singh. Leelamine is a novel inhibitor of fatty acid synthesis in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5081.

Abstract 5070: Sulforaphane is a novel inhibitor of breast cancer-induced osteolytic bone resorption

Bone is the preferred site for metastatic spread in women with advanced breast cancer, and skeletal complications is associated with high morbidity and mortality. Nearly 70% of luminal-type breast cancer patients with metastases to bone experience skeletal complications due to enhanced osteoclastogenesis (osteoclast activation) that increases bone resorption, pain, pathological fractures, spinal cord compression, and hypercalcemia. The present study was designed to determine the effect of a cruciferous vegetable component (Sulforaphane; SFN) on breast cancer-induced osteoclastogenesis. Osteoclast differentiation in mouse bone marrow monocytes (BMM) was inhibited significantly upon the addition of 10% conditioned-media (CM) from SFN-treated breast cancer cells belonging to different subtypes, including MDA-MB-231, MCF-7, and SK-BR-3, in comparison with corresponding control. PCR-based gene expression profiling identified a common set of genes downregulated by SFN treatment compared to vehicle-treated control in MDA-MB-231, MCF-7, and SK-BR-3 cells, including osteoclastogenesis promoting transcription factors (RUNX2, NF-κB, and SOX-9) and certain soluble molecules (MMP9, TNFα, and Cathepsin K). Many of these gene expression changes were confirmed in MDA-MB-231, MCF-7, and SK-BR-3 cells by RT-PCR or western blotting. To determine the in vivo efficacy, SFN was administrated orally (1 mg per mouse; three times/week) to athymic mice intracardially injected with MDA-MB-231-Luc cells. SFN administration significantly inhibited the multiplicity of bone metastases and increased the bone volume relative to total volume. SFN-mediated prevention of osteoclastogenesis was associated with a significant decrease in TRAP-positive osteoclasts in bones and the levels of Cathepsin K, IL-8, and RANKL in serum. Altogether, this study demonstrates, for the first time to the best of our knowledge, that SFN is a potent inhibitor of breast cancer-induced osteoclastogenesis and bone resorption in vitro and in vivo. This study was partly funded by a pilot project grant from the UPMC Hillman Cancer (NCI grant P30 CA047904; Robert L. Ferris- Principal Investigator) and RO1 CA142604 and CA129347 awarded by the National Cancer Institute (Shivendra Singh- Principal Investigator).

Citation Format: Subrata K. Pore, Joseph D. Latoche, Carolyn J. Anderson, Juraj Adamik, Deborah L. Galson, Kurt R. Weiss, Boeun Lee, Rebecca J. Watters, Prashant N. Kumta, Shivendra V. Singh. Sulforaphane is a novel inhibitor of breast cancer-induced osteolytic bone resorption [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5070.

Withaferin A-mediated apoptosis in breast cancer cells is associated with alterations in mitochondrial dynamics

Withaferin A (WA), a steroidal lactone derived from a medicinal plant (Withania somnifera), inhibits cancer development in transgenic and chemically-induced rodent models of breast cancer but the underlying mechanism is not fully grasped. We have shown previously that WA treatment causes apoptotic cell death in human breast cancer cells that is preceded by inhibition of complex III of the mitochondrial electron transport chain. This study extends these observations to now demonstrate alterations in mitochondrial dynamics in WA-induced apoptosis. Assembly of complex III was decreased in MCF-7 and SUM159 cells but not in MDA-MB-231 as determined by native blue gel electrophoresis. Because WA is a Michael acceptor (electrophile), we explored the possibility of whether it covalently modifies cysteine residue(s) in ubiquinol-cytochrome c reductase, Rieske iron-sulfur polypeptide 1 (UQCRFS1). Covalent modification of cysteine in UQCRFS1 was not observed after WA treatment. Instead, WA treatment inhibited chemically-induced mitochondrial fusion and decreased the mitochondrial volume, and this effect was accompanied by a decrease in the expression of proteins involved in fusion process, including mitofusin1, mitofusin2, and full-length optic atrophy protein 1 (OPA1). A loss of volume in fragmented mitochondria also occurred in WA-exposed cells when compared to vehicle-treated control. WA treatment also caused a decrease in protein level of mitochondrial fission-regulating protein dynamin-related protein 1 (DRP1). Functional studies revealed that DRP1 deficiency and OPA1 knockdown attenuated apoptotic potential of WA. Taken together, these results indicate that WA not only alters Complex III assembly but also inhibits mitochondrial dynamics in breast cancer cells.

Myoglobin induces mitochondrial fusion, thereby inhibiting breast cancer cell proliferation

Myoglobin is a monomeric heme protein expressed ubiquitously in skeletal and cardiac muscle and is traditionally considered to function as an oxygen reservoir for mitochondria during hypoxia. It is now well established that low concentrations of myoglobin are aberrantly expressed in a significant proportion of breast cancer tumors. Despite being expressed only at low levels in these tumors, myoglobin is associated with attenuated tumor growth and a better prognosis in breast cancer patients, but the mechanism of this myoglobin-mediated protection against further cancer growth remains unclear. Herein, we report a signaling pathway by which myoglobin regulates mitochondrial dynamics and thereby decreases cell proliferation. We demonstrate in vitro that expression of human myoglobin in MDA-MB-231, MDA-MB-468, and MCF7 breast cancer cells induces mitochondrial hyperfusion by up-regulating mitofusins 1 and 2, the predominant catalysts of mitochondrial fusion. This hyperfusion causes cell cycle arrest and subsequent inhibition of cell proliferation. Mechanistically, increased mitofusin expression was due to myoglobin-dependent free-radical production, leading to the oxidation and degradation of the E3 ubiquitin ligase parkin. We recapitulated this pathway in a murine model in which myoglobin-expressing xenografts exhibited decreased tumor volume with increased mitofusin, markers of cell cycle arrest, and decreased parkin expression. Furthermore, in human triple-negative breast tumor tissues, mitofusin and myoglobin levels were positively correlated. Collectively, these results elucidate a new function for myoglobin as a modulator of mitochondrial dynamics and reveal a novel pathway by which myoglobin decreases breast cancer cell proliferation and tumor growth by up-regulating mitofusin levels.

AKT-dependent sugar addiction by benzyl isothiocyanate in breast cancer cells

The overall promise of breast cancer chemoprevention is exemplified by clinical success of selective estrogen receptor modulators and aromatase inhibitors. Despite clinical efficacy, these interventions have limitations, including rare but serious side effects and lack of activity against estrogen receptor-negative breast cancers. We have shown previously that dietary administration of benzyl isothiocyanate (BITC), which occurs naturally as a thioglucoside conjugate in edible cruciferous vegetables, inhibits development of estrogen receptor-negative breast cancer in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice. This study demonstrates AKT-mediated sugar addiction in breast cancer chemoprevention by BITC. BITC-treated MMTV-neu mice exhibited increased 2-deoxy-2-(¹⁸ F)-fluoro-D-glucose (¹⁸ F-FDG) uptake in mammary tumors in vivo in comparison with mice fed basal diet. Cellular studies using MDA-MB-231 and SUM159 human breast cancer cell lines revealed BITC-mediated induction and punctate localization of glucose transporter GLUT-1, which was accompanied by an increase in intracellular pyruvate levels. BITC treatment resulted in increased S⁴⁷³ phosphorylation (activation) of AKT in cells in vitro as well as in mammary tumors of MMTV-neu mice in vivo. Increased glucose uptake, punctate pattern of GLUT-1 localization, and intracellular pyruvate levels resulting from BITC exposure were significantly attenuated in the presence of a pharmacological inhibitor of AKT (MK-2206). Inhibition of AKT augmented BITC-mediated inhibition of cell migration and colony formation. BITC-induced apoptotic cell death was also increased by pharmacological inhibition of AKT. These results indicate increased glucose uptake/metabolism by BITC treatment in breast cancer cells suggesting that breast cancer chemoprevention by BITC may be augmented by pharmacological inhibition of AKT.

Role of Krüppel-like Factor 4-p21CIP1 Axis in Breast Cancer Stem-like Cell Inhibition by Benzyl Isothiocyanate

Cancer chemoprevention by benzyl isothiocyanate (BITC), which is derived from cruciferous vegetables like garden cress, in a transgenic mouse model of breast cancer is associated with inhibition of breast cancer stem-like cells (bCSC), but the molecular regulators of this effect remain elusive. This study demonstrates a protective effect of Krüppel-like factor 4 (KLF4)-p21^CIP1 axis in bCSC inhibition by BITC. Exposure of human breast cancer cells (MCF-7, MDA-MB-231, and SUM159) to plasma-achievable concentrations of BITC resulted in a robust induction of KLF4 mRNA and its protein expression as determined by qRT-PCR and Western blotting or confocal microscopy. BITC-mediated suppression of bCSC markers, including aldehyde dehydrogenase 1 activity and mammosphere frequency, was significantly augmented by transient or stable knockdown of KLF4. Western blotting and IHC revealed relatively higher levels of KLF4 protein in mammary tumor sections from BITC-treated mice in comparison with controls, but the difference was insignificant. Analysis of the breast cancer RNA-Seq data from The Cancer Genome Atlas indicated significant positive correlation between expression of KLF4 and that of p21^CIP1 (CDKN1A) but not β-Catenin (CTNNB1). Knockdown of p21^CIP1 protein also amplified BITC-mediated suppression of bCSC. Finally, KLF4 was recruited to the promoter of p21^CIP1 as indicated by chromatin immunoprecipitation assay. These results indicate that induction of KLF4-p21^CIP1 axis attenuates inhibitory effect of BITC on bCSC self-renewal. Translational implication of these findings is that breast cancer chemoprevention by BITC may be augmented with a combination regimen involving BITC and an inhibitor of KLF4.

Prostate cancer chemoprevention by sulforaphane in a preclinical mouse model is associated with inhibition of fatty acid metabolism

Increased de novo synthesis of fatty acids is a rather unique and targetable mechanism of human prostate cancer. We have shown previously that oral administration of sulforaphane (SFN) significantly inhibits the incidence and/or burden of prostatic intraepithelial neoplasia and well-differentiated adenocarcinoma in TRansgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice. The present study used cellular models of prostate cancer and archived plasma/adenocarcinoma tissues and sections from the TRAMP study to demonstrate inhibition of fatty acid synthesis by SFN treatment in vitro and in vivo. Treatment of androgen-responsive (LNCaP) and castration-resistant (22Rv1) human prostate cancer cells with SFN (5 and 10 μM) resulted in downregulation of protein and mRNA levels of acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FASN), but not ATP citrate lyase. Protein and mRNA levels of carnitine palmitoyltransferase 1A (CPT1A), which facilitates fatty acid uptake by mitochondria for β-oxidation, were also decreased following SFN treatment in both cell lines. Immunohistochemistry revealed a significant decrease in expression of FASN and ACC1 proteins in prostate adenocarcinoma sections of SFN-treated TRAMP mice when compared with controls. SFN administration to TRAMP mice resulted in a significant decrease in plasma and/or prostate adenocarcinoma levels of total free fatty acids, total phospholipids, acetyl-CoA and ATP. Consistent with these results, number of neutral lipid droplets was lower in the prostate adenocarcinoma sections of SFN-treated TRAMP mice than in control tumors. Collectively, these observations indicate that prostate cancer chemoprevention by SFN in TRAMP mice is associated with inhibition of fatty acid metabolism.

Inhibition of NF-κB signaling pathway by astaxanthin supplementation for prevention of heat stress-induced inflammatory changes and apoptosis in Karan Fries heifers

Present study was conducted on 12 Karan Fries (Holstein Friesian X Tharparkar) heifers (10-12 months) to assess the effect of astaxanthin supplementation on heat stress amelioration and inhibition of NF-κB signaling pathway for prevention of heat stress-induced inflammatory changes and apoptosis in the cell during the summer season. The heifers were randomly and equally divided into two groups, i.e., control (fed as per ICAR 2013) and treatment groups (additionally supplemented astaxanthin at a dose rate of 0.25 mg/kg BW/day/animal). Temperature humidity index used to assess the levels of summer stress during the experimental period. Blood samples were collected at the fortnightly interval for quantification of plasma cortisol and IL-12 from both the groups of the heifers and from collected blood samples, RNA was isolated and transcribed into cDNA for real time PCR, for genes expression of NF-κB, IL-2, caspase-3, and Bcl-2. Plasma cortisol, IL-12 levels, and expression pattern of NF-κB, IL-2, and caspase-3 were significantly (P ≤ 0.05) lower in treatment group of Karan Fries heifers than control group, whereas, Bcl-2 was higher (P ≤ 0.05) in astaxanthin supplemented group. The temperature humidity index had a positive correlation (P ≤ 0.05) with plasma cortisol and IL-12 and expression pattern of NF-κB, IL-2, and caspase-3. However, it was negatively correlated with Bcl-2. The supplementation of astaxanthin can ameliorate the impact of summer stress through NF-κB downregulation, might be due to the quenching of free radicals, which regulates the expression of pro-inflammatory mediators and apoptotic genes.

Prevention of breast cancer-induced osteolytic bone resorption by benzyl isothiocyanate

Osteolytic bone resorption is the primary cause of pain and suffering (e.g. pathological bone fracture) in women with metastatic breast cancer. The current standard of care for patients with bone metastasis for reducing the incidence of skeletal complications includes bisphosphonates and a humanized antibody (denosumab). However, a subset of patients on these therapies still develops new bone metastasis or experiences adverse effects. Moreover, some bisphosphonates have poor oral bioavailability. Therefore, orally-bioavailable and non-toxic inhibitors of breast cancer-induced osteolytic bone resorption are still clinically desirable. We have shown previously that benzyl isothiocyanate (BITC) decreases the incidence of breast cancer in a transgenic mouse model without any side effects. The present study provides in vivo evidence for inhibition of breast cancer-induced osteolytic bone resorption by BITC. Plasma achievable doses of BITC (0.5 and 1 μM) inhibited in vitro osteoclast differentiation induced by co-culture of osteoclast precursor cells (RAW264.7) and breast cancer cells representative of different subtypes. This effect was accompanied by downregulation of key mediators of osteoclast differentiation, including receptor activator of nuclear factor-κB ligand and runt-related transcription factor 2 (RUNX2), in BITC-treated breast cancer cells. Doxycycline-inducible knockdown of RUNX2 augmented BITC-mediated inhibition of osteoclast differentiation. Oral administration of 10 mg BITC/kg body weight, 5 times per week, inhibited MDA-MB-231-induced skeletal metastasis multiplicity by ~81% when compared with control (P = 0.04). The present study indicates that BITC has the ability to inhibit breast cancer-induced osteolytic bone resorption in vivo.

Therapeutic Potential of Leelamine, a Novel Inhibitor of Androgen Receptor and Castration-Resistant Prostate Cancer

Clinical management of castration-resistant prostate cancer (CRPC) resulting from androgen deprivation therapy remains challenging. CRPC is driven by aberrant activation of androgen receptor (AR) through mechanisms ranging from its amplification, mutation, post-translational modification, and expression of splice variants (e.g., AR-V7). Herein, we present experimental evidence for therapeutic vulnerability of CRPC to a novel phytochemical, leelamine (LLM), derived from pine tree bark. Exposure of human prostate cancer cell lines LNCaP (an androgen-responsive cell line with mutant AR), C4-2B (an androgen-insensitive variant of LNCaP), and 22Rv1 (a CRPC cell line with expression of AR-Vs), and a murine prostate cancer cell line Myc-CaP to plasma achievable concentrations of LLM resulted in ligand-dependent (LNCaP) and ligand-independent (22Rv1) growth inhibition in vitro that was accompanied by downregulation of mRNA and/or protein levels of full-length AR as well as its splice variants, including AR-V7. LLM treatment resulted in apoptosis induction in the absence and presence of R1881. In silico modeling followed by luciferase reporter assay revealed a critical role for noncovalent interaction of LLM with Y739 in AR activity inhibition. Substitution of the amine group with an isothiocyanate functional moiety abolished AR and cell viability inhibition by LLM. Administration of LLM resulted in 22Rv1 xenograft growth suppression that was statistically insignificant but was associated with a significant decrease in Ki-67 expression, mitotic activity, expression of full-length AR and AR-V7 proteins, and secretion of PSA. This study identifies a novel chemical scaffold for the treatment of CRPC. Mol Cancer Ther; 17(10); 2079-90. ©2018 AACR.

Evaluation of Biodistribution of Sulforaphane after Administration of Oral Broccoli Sprout Extract in Melanoma Patients with Multiple Atypical Nevi

Broccoli sprout extract containing sulforaphane (BSE-SFN) has been shown to inhibit ultraviolet radiation-induced damage and tumor progression in skin. This study evaluated the toxicity and potential effects of oral BSE-SFN at three dosages. Seventeen patients who each had at least 2 atypical nevi and a prior history of melanoma were randomly allocated to 50, 100, or 200 μmol oral BSE-SFN daily for 28 days. Atypical nevi were photographed on days 1 and 28, and plasma and nevus samples were taken on days 1, 2, and 28. Endpoints assessed were safety, plasma and skin sulforaphane levels, gross and histologic changes, IHC for phospho-STAT3(Y705), Ki-67, Bcl-2, HMOX1, and TUNEL, plasma cytokine levels, and tissue proteomics. All 17 patients completed 28 days with no dose-limiting toxicities. Plasma sulforaphane levels pooled for days 1, 2, and 28 showed median postadministration increases of 120 ng/mL for 50 μmol, 206 ng/mL for 100 μmol, and 655 ng/mL for 200 μmol. Median skin sulforaphane levels on day 28 were 0.0, 3.1, and 34.1 ng/g for 50, 100, and 200 μmol, respectively. Plasma levels of proinflammatory cytokines decreased from day 1 to 28. The tumor suppressor decorin was increased from day 1 to 28. Oral BSE-SFN is well tolerated at daily doses up to 200 μmol and achieves dose-dependent levels in plasma and skin. A larger efficacy evaluation of 200 μmol daily for longer intervals is now reasonable to better characterize clinical and biological effects of BSE-SFN as chemoprevention for melanoma. Cancer Prev Res; 11(7); 429-38. ©2018 AACR.

Peptidyl-prolyl cis/trans isomerase Pin1 regulates withaferin A-mediated cell cycle arrest in human breast cancer cells

We have reported previously that withaferin A (WA) prevents breast cancer development in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice, but the mechanism is not fully understood. Unbiased proteomics of the mammary tumors from control- and WA-treated MMTV-neu mice revealed downregulation of peptidyl-prolyl cis/trans isomerase (Pin1) protein by WA administration. The present study extends these findings to elucidate the role of Pin1 in cancer chemopreventive mechanisms of WA. The mammary tumor level of Pin1 protein was lower by about 55% in WA-treated rats exposed to N-methyl-N-nitrosourea, compared to control. Exposure of MCF-7 and SK-BR-3 human breast cancer cells to WA resulted in downregulation of Pin1 protein. Ectopic expression of Pin1 attenuated G₂ and/or mitotic arrest resulting from WA treatment in both MCF-7 and SK-BR-3 cells. WA-induced apoptosis was increased by Pin1 overexpression in MCF-7 cells but not in the SK-BR-3 cell line. In addition, molecular docking followed by mass spectrometry indicated covalent interaction of WA with cysteine 113 of Pin1. Overexpression of Pin1^C113A mutant failed to attenuate WA-induced mitotic arrest or apoptosis in the MCF-7 cells. Furthermore, antibody array revealed upregulation of proapoptotic insulin-like growth factor binding proteins (IGFBPs), including IGFBP-3, IGFBP-4, IGFBP-5, and IGFBP-6, in Pin1 overexpressing MCF-7 cells following WA treatment when compared to empty vector transfected control cells. These data support a crucial role of the Pin1 for mitotic arrest and apoptosis signaling by WA at least in the MCF-7 cells.

Inhibition of Glycolysis in Prostate Cancer Chemoprevention by Phenethyl Isothiocyanate

We have shown previously that dietary administration of phenethyl isothiocyanate (PEITC), a small molecule from edible cruciferous vegetables, significantly decreases the incidence of poorly differentiated prostate cancer in Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice without any side effects. In this study, we investigated the role of c-Myc-regulated glycolysis in prostate cancer chemoprevention by PEITC. Exposure of LNCaP (androgen-responsive) and 22Rv1 (castration-resistant) human prostate cancer cells to PEITC resulted in suppression of expression as well as transcriptional activity of c-Myc. Prostate cancer cell growth inhibition by PEITC was significantly attenuated by stable overexpression of c-Myc. Analysis of the RNA-Seq data from The Cancer Genome Atlas indicated a significant positive association between Myc expression and gene expression of many glycolysis-related genes, including hexokinase II and lactate dehydrogenase A Expression of these enzyme proteins and lactate levels were decreased upon PEITC treatment in prostate cancer cells, and these effects were significantly attenuated by ectopic expression of c-Myc. A normal prostate stromal cell line (PrSC) was resistant to lactic acid suppression by PEITC treatment. Prostate cancer chemoprevention by PEITC in TRAMP mice was associated with a significant decrease in plasma lactate and pyruvate levels. However, a 1-week intervention with 10 mg PEITC (orally, 4 times/day) was not sufficient to decrease lactate levels in the serum of human subjects. These results indicated that although prostate cancer prevention by PEITC in TRAMP mice was associated with suppression of glycolysis, longer than 1-week intervention might be necessary to observe such an effect in human subjects. Cancer Prev Res; 11(6); 337-46. ©2018 AACR.

Abstract B74: Prevention of breast cancer by withanolides

Malignancy of the breast is a leading cause of cancer-related deaths among women globally. Feasibility of breast cancer prevention is illustrated by clinical success with SERMs and aromatase inhibitors for ER+ breast cancers. However, a clinically viable preventive intervention targeting ER-negative breast cancers is still lacking. Constituents of Ayurvedic medicine, which has been practiced in India for thousands of years, continue to draw attention for identification of novel small molecules potentially useful for prevention of chronic diseases including cancer. This presentation summarizes efficacy data, molecular targets, and biomarkers of mammary cancer prevention by a small-molecule steroidal lactone (withaferin A) derived from an Ayurvedic medicinal plant (Withania somnifera). This work was supported by the grant US PHS grant RO1 CA142694-05 from the National Cancer Institute.

Citation Format: Shivendra V. Singh. Prevention of breast cancer by withanolides [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr B74.

Abstract 5270: Disease subtype independent biomarkers of breast cancer prevention by withaferin a

Breast cancer is a rather complex and heterogeneous disease broadly grouped into four major subtypes, including luminal-type, basal-like, HER2 amplified, and normal-like, and each with a distinct molecular signature. A non-toxic chemopreventive intervention efficacious against different subtypes of breast cancer is still a clinically unmet need. The present study not only demonstrates chemoprevention of breast cancer in rats by the Ayurvedic medicine phytochemical withaferin A (WA) but also identifies its mechanistic biomarkers common to different subtypes of this disease. Chemopreventive efficacy of WA (4 and 8 mg per kg body weight) was determined using a rat model of breast cancer induced by N-methyl-N-nitrosourea (MNU). The mechanisms underlying breast cancer chemoprevention by WA were elucidated by western blotting, biochemical assays, immunohistochemistry, and cytokine profiling using plasma and tumors from the MNU-rat and/or mouse mammary tumor virus-neu (MMTV-neu) models. Inhibitory effect of WA on exit from mitosis and leptin-induced oncogenic signaling was determined using MCF-7 and MDA-MB-231 cells. Incidence, multiplicity, and burden of MNU-induced breast cancer in rats were decreased by WA administration. For example, the tumor weight in the 8 mg per kg group was lower by 67% compared with controls (P = 0.004). Mitotic arrest and apoptosis induction were common determinants of breast cancer chemoprevention by WA in the MNU-rat and MMTV-neu models. Cytokine profiling showed suppression of plasma leptin levels by WA in rats. WA inhibited leptin-induced oncogenic signaling in cultured MCF-7 and MDA-MB-231 cell lines. WA is a promising phytochemical with the ability to inhibit at least two different subtypes of breast cancer, including neu-driven estrogen receptor negative (ER-) breast cancer in MMTV-neu model and MNU-induced ER+ breast cancer in rats. This study was supported by the grant RO1 CA142604-07 awarded by the National Cancer Institute.

Citation Format: Eun-Ryeong Hahm, Suman K. Samanta, Anuradha Sehrawat, Su-Hyeong Kim, Subrata K. Pore, Krishna B. Singh, Susan M. Christner, Yongli Shuai, Jan H. Beumer, Ruchi Roy, Nancy E. Davidson, Shivendra V. Singh. Disease subtype independent biomarkers of breast cancer prevention by withaferin a [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5270. doi:10.1158/1538-7445.AM2017-5270

Abstract 5227: Synthesis of a biotin probe for identification of the ajoene protein targets in cancer cells ajoene protein targets in cancer cells

Garlic (Allium sativum) is a medicinal plant belonging to the lily family which has been used since ancient times for its beneficial health effects which include protection against infections and cancer. There are a cluster of bioactive compounds found in crushed garlic which contain sulfide or polysulfide functional groups. One of these compounds, ajoene, is able to interfere with biological processes by undergoing thiolysis exchange reactions with biological thiols, for example glutathione and cysteine residues on proteins. Importantly, ajoene is cytotoxic to cancer cells in the low micromolar range. We have previously found that ajoene targets multiple proteins in cancer cells and the aim of this project is to identify the specific protein targets of ajoene. To achieve this aim, we have synthesized a “tagged” ajoene analogue containing a biotin functional group. As biotin may alter the biological properties of ajoene, our strategy was to initially synthesize an azide-containing ajoene analogue (called azide-ajoene) using our 4-step synthetic route to ajoene analogues previously published. Azide-ajoene was found to retain cancer cell cytotoxicity similar to that of the parent ajoene. We then treated cancer cells (MDA-MB-231 breast and WHCO1 oesophageal cancer) with azide-ajoene to allow transfer of an azide label to the protein targets during thiolysis exchange with ajoene. We then collected lysate from the treated cells and performed an in vitro click reaction with a separately synthesized biotin-alkyne partner which was synthesized via a series of substitution and amide coupling reactions. Click chemistry covalently links biotin to the ajoene-tagged protein via a triazole linkage; and the feasibility of this method was validated by western blot. The biotinylated protein targets were purified using immobilised streptavidin beads and identified by MALDI-TOF mass spectrometry. It is anticipated that knowledge of the specific ajoene protein targets will provide valuable insights into the cytotoxic mechanism of action of ajoene in cancer cells.

Citation Format: Catherine H. Kaschula, Daniel A. Kusza, Georgia Schafer, Arieh A. Katz, Shivendra V. Singh, Roger Hunter. Synthesis of a biotin probe for identification of the ajoene protein targets in cancer cells ajoene protein targets in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5227. doi:10.1158/1538-7445.AM2017-5227

Abstract 5271: Prostate cancer chemoprevention by dietary isothiocyanates is associated with suppression of lipogenesis

Isothiocyanates (ITCs), including sulforaphane (SFN) and phenethyl isothiocyanate (PEITC), have been studied extensively for chemoprevention of prostate cancer using both in vitro and in vivo models, but the underlying mechanism is not fully understood. Dependence on fatty acid metabolism is progressively recognized as a unique trait of prostate cancer. Using in vitro and in vivo prostate cancer models, we demonstrate for the first time, that prostate cancer chemoprevention by ITCs is associated with suppression of fatty acid metabolism. Exposure of human prostate cancer cells to plasma achievable concentrations of SFN resulted in a marked decrease in levels of key fatty acid metabolism proteins, including acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FASN), and carnitine palmitoyl transferase 1A (CPT1A), that was accompanied by suppression of their transcription. Consistent with the in vitro results, oral administration of prostate cancer chemopreventive concentrations of SFN (6 µmol per mouse, three times per week) resulted in downregulation of ACC1, FASN, and CPT1A proteins in prostate adenocarcinoma of TRAMP transgenic mice when compared with control. Levels of fatty acid metabolites (free fatty acid, triglycerides and phospholipids), lactate, and acetyl-CoA were also lower in the plasma and/or prostate adenocarcinoma of SFN-treated TRAMP mice in comparison with controls. Because fatty acid oxidation is an important step to supply energy to the prostate cancer cells, we explored the possibility of whether SFN could affect the fatty acid oxidation in prostate cancer cells. Indeed, SFN exposure significantly decreased the level of proteins involved in fatty acid oxidation in prostate cancer cells. Many of these changes were also observed with PEITC. In conclusion, it is reasonable to propose that suppression of fatty acid metabolism is an important mechanism in prostate cancer chemoprevention by ITCs. This study was supported by the grants RO1 CA115498-10 and RO1 CA101753-12 awarded by the National Cancer Institute.

Citation Format: Krishna B. Singh, Shivendra V. Singh. Prostate cancer chemoprevention by dietary isothiocyanates is associated with suppression of lipogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5271. doi:10.1158/1538-7445.AM2017-5271

Abstract 5258: Benzyl isothiocyanate prevents breast cancer-induced bone erosion in vivo

Bone is one of the metastatic sites for advanced breast cancer. Nearly 70% of breast cancer patients experience metastasis to bone due to enhanced osteoclastogenesis and formation of osteoclasts leading to bone resorption. We have shown previously that benzyl isothiocyanate (BITC), a constituent of edible cruciferous vegetables such as garden cress, is a potent inhibitor of breast cancer cells in vitro and in vivo. The present study was designed to determine the effect of BITC on breast cancer-induced osteoclastogenesis. Co-culture of murine RAW 264.7 macrophages with human breast cancer cells resulted in genesis of osteoclasts in vitro that was suppressed significantly in the presence of BITC. Runx2, a transcription factor, is abnormally expressed in breast cancer and contributes to osteoclastogenesis by regulating receptor activator of NF-κB ligand (RANKL). BITC treatment downregulated expression of Runx2 in breast cancer cells at the mRNA and protein levels. Osteoclastogenesis was increased in Runx2 overexpressing MDA-MB-231 cells, whereas conditional knockdown of Runx2 in T47D cells attenuated this process. To determine the in vivo efficacy of BITC, MDA-MB-231-Luc cells were injected into the left ventricle of nude mice. BITC was administrated orally at 10 mg per kg body weight. Micro-CT X-ray analysis showed that bone metastases and erosion was decreased by about 50% upon BITC treatment when compared with vehicle control. Cathepsin K and total RANKL levels were lower in the plasma of BITC-treated mice when compared to the control group. Altogether, this study demonstrates, for the first time, that BITC is a potent inhibitor of breast cancer-induced osteoclastogenesis in vivo. This study was supported by the grant RO1 CA129347-09 awarded by the national Cancer Institute.

Citation Format: Subrata K. Pore, Shivendra V. Singh. Benzyl isothiocyanate prevents breast cancer-induced bone erosion in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5258. doi:10.1158/1538-7445.AM2017-5258

A rare presentation of exudative macroaneurysms in unilateral Eales’ disease

Background: A case of exudative macroaneurysms in unilateral Eales’ disease is reported. ‘Eales disease’ is an idiopathic bilateral occlusive periphlebitis with neovascularisation and mostly presents with vitreous hemorrhage. Case: A 30 year old male presented with diminution of vision in left eye (6/36) for 1 month. Slit Lamp examination of both eyes revealed normal anterior segment. Fundus examination of left eye with + 90 D lens revealed reddish lesions at the macula with surrounding circinate exudation. On peripheral examination hemorrhages were seen along with vasculitis in the superotemporal quadrant.The right eye fundus was normal.All laboratory investigations were found within normal limits. Conclusion: Eales’ disease is mostly a bilateral condition but this case is rare as there is uniocular involvement with exudative macroaneurysms.Laser therapy was instituted which was effective in management of this condition with restoration of normal visual acuity.There was no relapse on follow up for 2 years.