Chemoprevention of prostate cancer by d,l-sulforaphane is augmented by pharmacological inhibition of autophagy

There is a preclinical evidence that the oral administration of d,l-sulforaphane (SFN) can decrease the incidence or burden of early-stage prostate cancer [prostatic intraepithelial neoplasia (PIN)] and well-differentiated cancer (WDC) but not late-stage poorly differentiated cancer (PDC). Because SFN treatment induces cytoprotective autophagy in cultured human prostate cancer cells, the present study tested the hypothesis that chemopreventive efficacy of SFN could be augmented by the pharmacologic inhibition of autophagy using chloroquine (CQ). Incidence of PDC characterized by prostate weight of more than 1 g was significantly lower in the SFN + CQ group than in control (P = 0.004), CQ group (P = 0.026), or SFN group (P = 0.002 by Fisher exact test). Average size of the metastatic lymph node was lower by about 42% in the SFN + CQ group than in control (P = 0.043 by Wilcoxon test). On the other hand, the SFN + CQ combination was not superior to SFN alone with respect to inhibition of incidence or burden of microscopic PIN or WDC. SFN treatment caused in vivo autophagy as evidenced by transmission electron microscopy. Mechanistic studies showed that prevention of prostate cancer and metastasis by the SFN + CQ combination was associated with decreased cell proliferation, increased apoptosis, alterations in protein levels of autophagy regulators Atg5 and phospho-mTOR, and suppression of biochemical features of epithelial-mesenchymal transition. Plasma proteomics identified protein expression signature that may serve as biomarker of SFN + CQ exposure/response. This study offers a novel combination regimen for future clinical investigations for prevention of prostate cancer in humans.

Metabolic alterations in mammary cancer prevention by withaferin A in a clinically relevant mouse model

BACKGROUND

Efficacy of withaferin A (WA), an Ayurvedic medicine constituent, for prevention of mammary cancer and its associated mechanisms were investigated using mouse mammary tumor virus-neu (MMTV-neu) transgenic model.

METHODS

Incidence and burden of mammary cancer and pulmonary metastasis were scored in female MMTV-neu mice after 28 weeks of intraperitoneal administration with 100 µg WA (three times/week) (n = 32) or vehicle (n = 29). Mechanisms underlying mammary cancer prevention by WA were investigated by determination of tumor cell proliferation, apoptosis, metabolomics, and proteomics using plasma and/or tumor tissues. Spectrophotometric assays were performed to determine activities of complex III and complex IV. All statistical tests were two-sided.

RESULTS

WA administration resulted in a statistically significant decrease in macroscopic mammary tumor size, microscopic mammary tumor area, and the incidence of pulmonary metastasis. For example, the mean area of invasive cancer was lower by 95.14% in the WA treatment group compared with the control group (mean = 3.10 vs 63.77 mm2, respectively; difference = -60.67 mm2; 95% confidence interval = -122.50 to 1.13 mm2; P = .0536). Mammary cancer prevention by WA treatment was associated with increased apoptosis, inhibition of complex III activity, and reduced levels of glycolysis intermediates. Proteomics confirmed downregulation of many glycolysis-related proteins in the tumor of WA-treated mice compared with control, including M2-type pyruvate kinase, phospho glycerate kinase, and fructose-bisphosphate aldolase A isoform 2.

CONCLUSIONS

This study reveals suppression of glycolysis in WA-mediated mammary cancer prevention in a clinically relevant mouse model.

Dietary chemopreventative benzyl isothiocyanate inhibits breast cancer stem cells in vitro and in vivo

A small subset of mammary tumor-initiating cells (also known as breast cancer stem cells; bCSC), characterized by expression of different markers [CD44(high)/CD24(low)/epithelial-specific antigen (ESA)+], aldehyde dehydrogenase-1 (ALDH1) activity, and ability to form mammospheres under ultra-low attachment culture conditions, are suspected to evade conventional therapies leading to disease recurrence. Elimination of both therapy-sensitive epithelial tumor cells and therapy-resistant bCSC is therefore necessary for prevention of breast cancer. We have shown previously that a nontoxic small-molecule constituent of edible cruciferous vegetables (benzyl isothiocyanate; BITC) inhibits mammary cancer development in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice by causing epithelial tumor cell apoptosis. The present study shows efficacy of BITC against bCSC in vitro and in vivo. Mammosphere formation frequency and CD44(high)/CD24(low)/ESA+ and/or ALDH1+ populations in cultured MCF-7 (estrogen receptor-positive) and SUM159 (triple-negative) human breast cancer cells were decreased significantly in the presence of plasma achievable concentrations of BITC. BITC administration in the diet (3 μmol BITC/g diet for 29 weeks) resulted in a marked decrease in bCSCs in the MMTV-neu mice tumors in vivo. Overexpression of full-length Ron as well as its truncated form (sfRon), but not urokinase-type plasminogen activator receptor, conferred near complete protection against BITC-mediated inhibition of bCSCs in MCF-7 cells. The BITC treatment downregulated protein levels of Ron and sfRon in cultured breast cancer cells and in tumor xenografts. Ron overexpression resulted in upregulation of bCSC-associated genes Oct-4, SOX-2, and Nanog. In conclusion, the present study indicates that BITC treatment eliminates bCSCs in vitro and in vivo.

Abstract 3671: The role of FOXQ1 in benzyl isothiocyanate-mediated inhibition of epithelial-mesenchymal transition in human breast cancer cells

We have shown previously that breast cancer chemoprevention by benzyl isothiocyanate (BITC) in mouse mammary tumor virus-neu transgenic mice is associated with induction of E-cadherin protein expression. Loss of E-cadherin expression concomitant with induction of mesenchymal markers (eg, vimentin and fibronectin) is a biochemical hallmark of epithelial-to-mesenchymal transition (EMT). EMT is a developmental process but implicated in progression of cancer to aggressive state. We have also shown previously that BITC treatment inhibits EMT in cultured MDA-MB-231 human breast cancer cells. The present study extends these observations and investigates the mechanism by which BITC inhibits EMT. Initially, we designed experiments using another triple-negative human breast cancer cell line (SUM159) to determine generality of the BITC-mediated inhibition of EMT. Exposure of SUM159 cells to pharmacologically-relevant concentrations of BITC (2.5 and 5 μM) resulted in induction of E-cadherin protein expression, which was accompanied by suppression of vimentin protein level especially at the 5 μM dose. Protein levels of slug and snail, which are transcriptional repressors of E-cadherin, were also decreased markedly after treatment of SUM159 cells with BITC, but this effect was relatively more pronounced on slug protein level compared with snail. Similar to MDA-MB-231 cells, the BITC-mediated induction of E-cadherin protein expression in SUM159 cells was accompanied by its transcriptional upregulation as revealed by E-cadherin luciferase reporter assay. Immunofluorescence microscopy confirmed induction of E-cadherin protein and suppression of vimentin protein expression in BITC-treated SUM159 cells. BITC treatment resulted in downregulation of Forkhead Box Q1 transcription factor (FOXQ1) protein and FOXQ1 mRNA in MDA-MB-231, SUM159, and MDA-MB-468 cells. The BITC-mediated inhibition of MDA-MB-231 xenograft growth in vivo was associated with suppression of FOXQ1 protein level. Ectopic expression of FOXQ1 in a mammary epithelial cell line conferred marked protection against BITC-mediated inhibition of EMT as well as cell migration. In conclusion, the present study implicates FOXQ1 suppression in BITC-mediated inhibition of EMT in human breast cancer cells. This study was supported by the grant CA129347-06 awarded by the National Cancer Institute.

Citation Format: Anuradha Sehrawat, Su-Hyeong Kim, Andreas Vogt, Shivendra V. Singh. The role of FOXQ1 in benzyl isothiocyanate-mediated inhibition of epithelial-mesenchymal transition in human breast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3671. doi:10.1158/1538-7445.AM2013-3671

Abstract 175: Prevention of mammary carcinogenesis and pulmonary metastasis by Ayurvedic medicine constituent withaferin A in a clinically-relevant transgenic mouse model

Novel strategies for prevention of breast cancer are desirable mainly because many risk factors associated with this disease are not easily modifiable. In addition, currently available clinical options for prevention of breast cancer (eg, selective estrogen receptor modulators and aromatase inhibitors) are sub-optimal. Recent literature highlights merit of plants used in Ayurvedic medicine, which has been practiced for centuries in India for treatment of different disorders, for identification of novel cancer preventive agents. Withania somnifera (also known as Ashwagandha) is one such medicinal plant that is used to alleviate a variety of symptoms. In experimental models, the known pharmacological effects of Withania somnifera include cardioprotection from ischemia reperfusion injury, inhibition of experimental Parkinsonism, suppression of hepatic lipid peroxidation, antibacterial effects, and anticancer effects. Anticarcinogenic effect of Withania somnifera is ascribed to withanolides such as withaferin A (WA). We have shown previously that WA treatment inhibits growth of cultured and xenografted human breast cancer cells by causing apoptotic cell death. The present study extends these observations and determines efficacy of WA for prevention of breast cancer in a clinically-relevant transgenic mouse model (MMTV-neu). Incidence and burden of mammary cancer and pulmonary metastasis were scored in female MMTV-neu mice after 28 weeks of intraperitoneal administration (three times/week) with 0.1 mg WA (n = 32) or vehicle (n = 29). This mild-regimen of WA administration resulted in a statistically significant decrease in macroscopic (palpable) tumor size, microscopic tumor area, and incidence of pulmonary metastasis. For example, the mean wet weight of the palpable tumor was lower by 50% in WA-treated mice compared with control mice (P = 0.03). Likewise, the area of invasive mammary cancer was lower by 95.14% in WA-treated mice compared with control mice (P = 0.05). The WA-treated mice exhibited a 72.8% decrease in incidence of pulmonary metastasis compared with the control mice (P = 0.02). Immunohistochemistry revealed reduced expression of HER-2 in tumors from WA-treated mice compared with control. Furthermore, consistent with cellular observations, mammary cancer prevention by WA treatment was associated with increased apoptosis index, inhibition of complex III activity, and increased staining for 8-oxo-dG (an indicator of oxidative stress). In conclusion, the results of the present study indicate that WA inhibits mammary carcinogenesis in a transgenic mouse model by causing apoptosis. This study was supported by the grant CA142604 awarded by the National Cancer Institute.

Citation Format: Eun-Ryeong Hahm, Joomin Lee, Su-Hyeong Kim, Anuradha Sehrawat, Julie A. Arlotti, Sruti Sajjan Shiva, Rohit Bhargava, Shivendra V. Singh. Prevention of mammary carcinogenesis and pulmonary metastasis by Ayurvedic medicine constituent withaferin A in a clinically-relevant transgenic mouse model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 175. doi:10.1158/1538-7445.AM2013-175

Abstract 3695: Augmentation of D,L-sulforaphane-mediated prostate cancer chemoprevention by pharmacologic inhibition of autophagy using chloroquine in a transgenic mouse model

D,L-Sulforaphane (SFN) is a synthetic racemic analogue of broccoli constituent L-sulforaphane with in vivo evidence of cancer chemopreventive effect in rodent models. For example, we showed previously that oral administration of 6 μmol (about 1 mg/mouse) SFN (3x/week) modestly inhibited incidence and/or burden of prostatic intraepithelial neoplasia and well-differentiated cancer, but not poorly-differentiated (advanced) prostate cancer, in Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice in association with apoptosis induction. Previous studies from our laboratory have also revealed that SFN treatment causes autophagy in cultured human prostate cancer cells, which serves to inhibit apoptotic cell death by delaying release of cytochrome c due to sequestration of mitochondria in autophagosomes. However, the in vivo significance of these cellular observations was unclear. The present study demonstrates, for the first time, in vivo augmentation of SFN-mediated prostate cancer chemoprevention by pharmacologic suppression of autophagy using chloroquine (CQ). A total of 128 four-week old TRAMP mice were randomized into one of the following four groups: (1) control (n=32), (2) SFN (n=32), (3) CQ (n=35), and (4) SFN + CQ (n=29). Termination of the experiment was planned after 18 weeks of treatment, but early sacrifice was necessary for some mice in each group (mostly from groups 1-3) due to a variety of reasons but not unique to any treatment group, including weight loss, premature death, morbidity, or early tumor onset. Nevertheless, % mice with prostate weight of >1g, an indicator of advanced (poorly-differentiated) prostate cancer, was significantly lower in the SFN + CQ group compared with control (P=0.006 by Fisher's exact test), SFN alone (P=0.017), and CQ alone group (P=0.072). Likewise, the incidence and burden of microscopic poorly-differentiated prostate cancer was significantly lower in the mice of the SFN + CQ group compared with control. Transmission electron microscopy confirmed in vivo autophagy induction by SFN administration in the dorsolateral prostate. Augmentation of SFN-mediated prostate cancer chemoprevention by CQ was associated with reduced cell proliferation. Plasma proteomics indicated protein level changes unique to the SFN + CQ combination compared with other groups (control or SFN), including hemopexin, serpina1c protein, and fructose-bisphosphate aldolase A isoform precursor. Cluster analysis of proteomics data revealed significant enrichment for gene ontology (GO) terms proteasome and threonine protease (2.8), protease inhibitor (2.7), and protein-lipid complex (2.6). These results merit determination of the efficacy of SFN + CQ combination for prevention of prostate cancer in a clinical setting. This investigation was supported by the NCI grant CA115498-07.

Citation Format: Avani R. Vyas, Eun-Ryeong Hahm, Julie A. Arlotti, Dhimant Desai, Shantu Amin, Shivendra V. Singh. Augmentation of D,L-sulforaphane-mediated prostate cancer chemoprevention by pharmacologic inhibition of autophagy using chloroquine in a transgenic mouse model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3695. doi:10.1158/1538-7445.AM2013-3695

Abstract 3670: The role of reactive oxygen species in anticancer effects of diallyl trisulfide, a bioactive component of garlic

Diallyl trisulfide (DATS) is a bioactive component of processed garlic with in vivo activity against chemically-induced as well as oncogene-driven cancer in rodent models. However, the mechanisms underlying anticancer effects of DATS (eg, growth inhibition, apoptosis induction, and suppression of migration in cancer cells) are not fully understood. The present study reveals a critical role for reactive oxygen species (ROS) in cellular anticancer responses to DATS. Exposure of human breast cancer cells (MDA-MB-231 and MCF-7) as well as a cell line derived from spontaneously developing mammary tumor of a MMTV-neu transgenic mouse (BRI-JM04) to DATS resulted in dose-dependent inhibition of cell viability and apoptosis induction. Interestingly, a non-tumorigenic normal human mammary cell line (MCF-10A) was resistant to growth inhibition and apoptosis induction by DATS. The DATS-induced apoptosis in MDA-MB-231, MCF-7, and BRI-JM04 cells was associated with ROS production as evidenced by fluorescence microscopy and flow cytometry using a chemical probe (MitoSOX Red). Ectopic expression of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) as well as Mn-SOD conferred significant protection against DATS-induced ROS production and apoptotic cell death. The DATS treatment caused activation of Bax and Bak, and activation of Bak was nearly fully abolished by overexpression of Mn-SOD. Likewise, inhibition of MDA-MB-231 and MCF-7 cell migration resulting from DATS treatment was partially but statistically significantly attenuated by stable overexpression of Cu,Zn-SOD and Mn-SOD. This protection against inhibition of cell migration was attributable to abrogation of DATS-mediated induction of E-cadherin and suppression of vimentin. These results indicate that ROS play an important role in anticancer effects of DATS at least in human breast cancer cells. This study was supported by grant CA113363-07 awarded by the National Cancer Institute.

Citation Format: Julie A. Arlotti, Kumar Chandra-Kuntal, Shivendra V. Singh. The role of reactive oxygen species in anticancer effects of diallyl trisulfide, a bioactive component of garlic. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3670. doi:10.1158/1538-7445.AM2013-3670

Abstract 3714: Metabolomics and proteomics reveal inhibition of glycolysis in withaferin A-mediated prevention of mammary carcinogenesis in MMTV-neu mice

Plants used in Ayurvedic medicine, which has been practiced for centuries in India for the treatment of different ailments, continue to draw attention for identification of novel small molecule cancer chemopreventive agents. Withaferin A (WA) is one such promising small molecule constituent of the medicinal plant Withania somnifera (also known as Ashwagandha) with in vivo activity against xenografted human breast cancer cells. We have also shown recently that mammary cancer development and pulmonary metastasis in MMTV-neu transgenic mice is inhibited significantly by WA administration. In the present study, we performed metabolomics profiling using plasma and tumor tissues (n=8) and proteomics profiling using tumor tissues (n=3) from control and WA-treated MMTV-neu mice to gain insights into the mechanism underlying in vivo preventive effect of WA. A total of 320 and 328 biochemicals of known identity were detectable in the plasma and tumor tissue, respectively. The WA-mediated mammary cancer prevention in MMTV-neu mice was associated with a statistically significant alteration (P≤0.05) in the levels of 76 biochemicals in the plasma (24 increase, 52 decrease). Metabolomics using tumor tissues revealed alterations in the levels of 24 biochemicals (2 increase, 24 decrease) upon WA administration. One change that was highly consistent in the plasma and tumor tissue from WA-treated mice compared to controls was a decrease in glucose utilization, glycolysis, and TCA cycle activity. Proteomics using tumor tissues confirmed downregulation of many glycolysis-related proteins in the tumor of WA-treated mice compared with control, including M2-type pyruvate kinase, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and fructose-bisphosphate aldolase A isoform 2. Downregulation of TCA cycle-related proteins in the tumor of WA-treated mice compared with control included pyruvate carboxylase and isocitrate dehydrogenase. Other altered biochemicals were reflective of changes in arginine metabolism, polyamine biosynthesis, glutathione metabolism, lipid metabolism, and catabolism of branched-chain amino acids. These observations indicate that WA treatment prevents mammary cancer in MMTV-neu mice by suppressing glycolysis (Warburg effect) and TCA cycle. This study was supported by the grant CA142604 awarded by the National Cancer Institute.

Citation Format: Shivendra V. Singh, Eun-Ryeong Hahm, Joomin Lee, Su-Hyeong Kim, Anuradha Sehrawat, Julie A. Arlotti. Metabolomics and proteomics reveal inhibition of glycolysis in withaferin A-mediated prevention of mammary carcinogenesis in MMTV-neu mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3714. doi:10.1158/1538-7445.AM2013-3714

Abstract 3687: Benzyl isothiocyanate downregulates Ronβ and sfRon to inhibit self-renewal of breast cancer stem cells

Recent studies suggest that cancer stem cells play a major role not only in the initiation and maintenance of breast cancer but also in clinical response to therapy. Breast cancer stem cells (bCSC) are characterized by their ability to self-renew (asymmetrical division into a daughter bCSC and a progeny), form spheres under ultra-low attachment conditions in vitro, and express unique cell-surface markers (eg, CD44, ESA). Elimination of both therapy-resistant bCSC and therapy-sensitive epithelial tumor cells may be required for effective prevention of breast cancers. We have shown previously that dietary administration of benzyl isothiocyanate (BITC), a small molecule constituent of many edible cruciferous vegetables (eg, garden cress), significantly inhibits mammary cancer development in a transgenic mouse model (MMTV-neu) in association with apoptosis induction and tumor infiltration of T cells. The present study was undertaken to determine the effect of BITC on bCSC. Exposure of MCF-7 (an estrogen-responsive cell line) and SUM159 (a triple-negative cell line) human breast cancer cells to pharmacologic doses of BITC (0.5-2.5 μM) resulted in inhibition of mammosphere formation (first generation after BITC treatment and subsequent generations without BITC treatment), aldehyde dehydrogenase 1 (ALDH1) activity, and CD44high/CD24low/ESA+ population. Inhibition of bCSC self-renewal resulting from BITC exposure was accompanied by down-regulation of urokinase-type plasminogen activator (uPAR), Bmi-1, and Ron (Ronβ and sfRon) proteins in vitro and in MDA-MB-231 xenografts in vivo (uPAR and Bmi-1). Ectopic expression of uPAR alone was sufficient to drive stemness in MCF-7 and MDA-MB-468 cells. However, the BITC-mediated inhibition of mammosphere formation and ALDH1 activity was sustained even after stable overexpression of uPAR in MCF-7 or MDA-MB-468 cells. Similarly, Bmi-1 overexpression was largely dispensable for BITC-mediated suppression of bCSC. On the other hand, overexpression of Ron (full-length) as we as sfRon in MCF-7 cells conferred significant protection against BITC-mediated inhibition of bCSC self-renewal. Ectopic expression of sfRon, but not Ron, resulted in nearly 4-fold increase in ALDH1 activity compared with control cells. Novel conclusions of the present study are: (a) overexpression of sfRon is sufficient to drive stemness at least in MCF-7 cells (b) mammary cancer prevention by BITC likely involves removal of bCSC, and (c) BITC-mediated inhibition of bCSC is caused by suppression of Ron signaling. This study was supported by the grant CA129347-06 awarded by the National Cancer Institute.

Citation Format: Su-Hyeong Kim, Anuradha Sehrawat, Shivendra V. Singh. Benzyl isothiocyanate downregulates Ronβ and sfRon to inhibit self-renewal of breast cancer stem cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3687. doi:10.1158/1538-7445.AM2013-3687

Abstract 3682: Differential effect of withaferin A treatment on activation of Notch1 and Notch2 in human breast cancer cells

Withaferin A (WA), a constituent of the Ayurvedic medicine plant Withania somnifera, exhibits in vivo efficacy against human breast cancer xenografts in athymic mice as well as spontaneous mammary cancer development in MMTV-neu transgenic mice. However, the mechanism underlying anticancer effect of WA is not fully understood. The present study was undertaken to determine the role of Notch family of transcription factors in anticancer effects of WA using human breast cancer cells as a model. Notch activation is linked to mammary carcinogenesis as evidenced by the following observations: (a) overexpression of activated Notch1 and Notch3 in transgenic mice blocks mammary gland development but induces tumorigenesis of the breast; (b) high level expression of Notch1 and its ligands is associated with poor outcome in breast cancer; (c) expression of Notch ligand Jagged1 is associated with recurrence in lymph node-negative breast cancer; and (d) Notch1 is involved in migration and invasion of human breast cancer cells. The present study reveals differential effect of WA treatment on activation of Notch1 versus Notch2 in human breast cancer cells. Exposure of MDA-MB-231 (an estrogen-independent cell line with mutant p53) and MCF-7 (an estrogen-responsive cell line with wild-type p53) human breast cancer cells to pharmacological concentrations of WA (2 and 4 μM) resulted in cleavage (suggesting activation) of Notch2, which was accompanied by transcriptional activation of Notch as evidenced by RBP-Jk, HES-1A/B, and HEY-1 luciferase reporter assays. On the other hand, WA treatment caused a decrease in levels of both transmembrane and cleaved (active) Notch1. The WA-mediated activation of Notch2 was associated with induction of γ-secretase complex components presenilin1 and/or nicastrin. Inhibition of MDA-MB-231 and MDA-MB-468 cell migration resulting from WA exposure was statistically significantly augmented by knockdown of Notch2 using siRNA and shRNA. Activation of Notch2 was not observed in cells treated with withanone or withanolide A, which are structural analogs of WA. Moreover, withanone and withanolide A were practically inactive against MDA-MB-231 cell migration. The results of the present study suggest that anti-metastatic effect of WA may be augmented in the presence of Notch2 inhibitors. This study was supported by the grant CA142604 awarded by the National Cancer Institute.

Citation Format: Joomin Lee, Anuradha Sehrawat, Shivendra V. Singh. Differential effect of withaferin A treatment on activation of Notch1 and Notch2 in human breast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3682. doi:10.1158/1538-7445.AM2013-3682

Differential effects of phenethyl isothiocyanate and D,L-sulforaphane on TLR3 signaling

Naturally occurring isothiocyanates (ITCs) from cruciferous vegetables are widely studied for their cancer chemopreventive effects. In this study, we investigated the effects of ITCs on TLR signaling, and found that the two most promising ITCs, phenethyl ITCs (PEITC) and D,L-sulforaphane (SFN), have differential effects on dsRNA-mediated innate immune signaling through TLR3. PEITC preferentially inhibited TLR3-mediated IFN regulatory factor 3 (IRF3) signaling and downstream gene expression in vivo and in vitro, whereas SFN caused inhibition of TLR3-mediated NF-κB signaling and downstream gene expression. Mechanistically, PEITC inhibited ligand (dsRNA)-dependent dimerization of TLR3, resulting in inhibition of signaling through IFN regulatory factor 3. In contrast, SFN did not disrupt TLR3 dimerization, indicating that it affects further downstream pathway resulting in NF-κB inhibition. To examine the biological significance of these findings in the context of antitumor activities of these compounds, we used two approaches: first, we showed that dsRNA-mediated apoptosis of tumor cells via TLR3 was inhibited in the presence of PEITC, whereas this response was augmented by SFN treatment; second, in a separate assay measuring anchorage-independent growth and colony formation by immortalized fibroblasts, we made similar observations. Again in this study, PEITC antagonized dsRNA-mediated inhibition of colony formation, whereas SFN enhanced the inhibition. These results indicate biologically relevant functional differences between two structurally similar ITCs and may provide important insights in therapeutic development of these compounds targeted to specific cancer.

Critical role for reactive oxygen species in apoptosis induction and cell migration inhibition by diallyl trisulfide, a cancer chemopreventive component of garlic

Diallyl trisulfide (DATS) is a structurally simple but biologically active constituent of processed garlic with in vivo activity against chemically induced as well as oncogene-driven cancer in experimental rodents. This study offers novel insights into the mechanisms underlying anticancer effects of DATS using human breast cancer cells as a model. Exposure of human breast cancer cells (MCF-7 and MDA-MB-231) and a cell line derived from spontaneously developing mammary tumor of a transgenic mouse (BRI-JM04) to DATS resulted in a dose-dependent inhibition of cell viability that was accompanied by apoptosis induction. A non-tumorigenic normal human mammary cell line (MCF-10A) was resistant to growth inhibition and apoptosis induction by DATS. The DATS-induced apoptosis in MDA-MB-231, MCF-7, and BRI-JM04 cells was associated with reactive oxygen species (ROS) production as evidenced by fluorescence microscopy and flow cytometry using a chemical probe (MitoSOX Red). Overexpression of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) as well as Mn-SOD conferred significant protection against DATS-induced ROS production and apoptotic cell death in MDA-MB-231 and MCF-7 cells. Activation of Bak, but not Bax, resulting from DATS treatment was markedly suppressed by overexpression of Mn-SOD. The DATS treatment caused ROS generation, but not activation of Bax or Bak, in MCF-10A cells. Furthermore, the DATS-mediated inhibition of cell migration was partially but significantly attenuated by Cu,Zn-SOD and Mn-SOD overexpression in association with changes in levels of proteins involved in epithelial-mesenchymal transition. The DATS-mediated induction of heme oxygenase-1 was partially attenuated by overexpression of Mn-SOD. These results provide novel mechanistic insights indicating a critical role for ROS in anticancer effects of DATS.

Suppression of FOXQ1 in benzyl isothiocyanate-mediated inhibition of epithelial-mesenchymal transition in human breast cancer cells

We showed previously that breast cancer chemoprevention with benzyl isothiocyanate (BITC) in MMTV-neu mice was associated with induction of E-cadherin protein in vivo. Loss of E-cadherin expression and induction of mesenchymal markers (e.g. vimentin) are biochemical hallmarks of epithelial-mesenchymal transition (EMT), a developmental process implicated in progression of cancer to aggressive state. This study offers novel insights into the mechanism by which BITC inhibits EMT. Exposure of MDA-MB-231, SUM159 and MDA-MB-468 human breast cancer cells to BITC (2.5 and 5 µM) resulted in transcriptional repression of urokinase-type plasminogen activator (uPA) as well as its receptor (uPAR). However, ectopic expression of uPAR in MDA-MB-468 cells failed to confer protection against induction of E-cadherin and inhibition of cell invasion/migration resulting from BITC treatment. The BITC-mediated induction of E-cadherin and inhibition of cell migration was sustained in MDA-MB-231 and SUM159 cells transiently transfected with an uPAR-targeted small interfering RNA. Overexpression of Forkhead Box Q1 (FOXQ1), whose protein and messenger RNA levels were decreased by BITC treatment in cells and MDA-MB-231 xenografts, conferred marked protection against BITC-mediated inhibition of EMT and cell migration. In conclusion, this study implicates FOXQ1 suppression in BITC-mediated inhibition of EMT in human breast cancer cells.

Zerumbone causes Bax- and Bak-mediated apoptosis in human breast cancer cells and inhibits orthotopic xenograft growth in vivo

The present study was undertaken to determine the anticancer efficacy of zerumbone (ZER), a sesquiterpene from subtropical ginger, against human breast cancer cells in vitro and in vivo. ZER treatment caused a dose-dependent decrease in viability of MCF-7 and MDA-MB-231 human breast cancer cells in association with G(2)/M phase cell cycle arrest and apoptosis induction. ZER-mediated cell cycle arrest was associated with downregulation of cyclin B1, cyclin-dependent kinase 1, Cdc25C, and Cdc25B. Even though ZER treatment caused stabilization of p53 and induction of PUMA, these proteins were dispensable for ZER-induced cell cycle arrest and/or apoptosis. Exposure of MDA-MB-231 and MCF-7 cells to ZER resulted in downregulation of Bcl-2 but its ectopic expression failed to confer protection against ZER-induced apoptosis. On the other hand, the SV40 immortalized mouse embryonic fibroblasts derived from Bax and Bak double knockout mice were significantly more resistant to ZER-induced apoptosis. ZER-treated MDA-MB-231 and MCF-7 cells exhibited a robust activation of both Bax and Bak. In vivo growth of orthotopic MDA-MB-231 xenografts was significantly retarded by ZER administration in association with apoptosis induction and suppression of cell proliferation (Ki-67 expression). These results indicate that ZER causes G(2)/M phase cell cycle arrest and Bax/Bak-mediated apoptosis in human breast cancer cells, and retards growth of MDA-MB-231 xenografts in vivo.

Public health response to the first case of Japanese encephalitis in Delhi, 2011

Japanese Encephalitis (JE) is an acute viral zoonotic infection of the central nervous system. A confirmed case of JE was reported in the MVH, Pooth Khurd, following which the epidemiological investigation was carried out in the study area. Clinical/Syndromic surveillance started in the hospital. The local practitioners and anganwadi workers were contacted and requested to report similar cases in their areas. Serosurveillance to delineate high risk population, animal and vector survey done by taking transect walks through the colony to look for presence of amplifying hosts like pigs, ducks etc. Out of 2328 persons surveyed, 404 persons were found to have/had fever in the preceding one month. Current fever cases were 166, out of which 9 fitted into the criteria of AES. Large water body with vegetations was present within the colony. Piggeries and ducks were found in the colony. In the hospital 9 AES cases were screened. In total only 18 (9 from field, 9 from hospital) cases subjected to testing and found to be negative for IgM specific for JE. In total only 18 (9 from field, 9 from hospital) cases subjected to testing and found to be negative for IgM specific for JE. Most probably the above case of nine year child is the first case of JE indigenous to Delhi. The environmental conditions were conducive for the transmission of the viral agent. Further research is hence recommended to find the missing links and to prevent outbreaks in Delhi.

Withaferin A-induced apoptosis in human breast cancer cells is associated with suppression of inhibitor of apoptosis family protein expression

The present study provides novel insight into the mechanism of apoptosis induction by withaferin A (WA), which is a bioactive constituent of an Ayurvedic medicine plant (Withania somnifera). Exposure of MDA-MB-231 and MCF-7 human breast cancer cells to WA resulted in suppression of XIAP, cIAP-2, and Survivin protein levels. The WA-induced apoptosis was significantly attenuated by ectopic expression of XIAP, Survivin, and cIAP-2 in both cells. However, the WA-mediated inhibition of MDA-MB-231 xenograft growth in vivo was associated with suppression of Survivin protein level only. These results indicate important contribution of Survivin suppression in WA-induced apoptosis.

Biomarkers of phenethyl isothiocyanate-mediated mammary cancer chemoprevention in a clinically relevant mouse model

BACKGROUND

Phenethyl isothiocyanate (PEITC) is a natural plant compound with chemopreventative potential against some cancers and the ability to induce apoptosis in breast cancer cells.

METHODS

Female mouse mammary tumor virus-neu mice were fed a control AIN-76A diet (n = 35) or the same diet supplemented with 3 µmol PEITC/g diet (n = 33) for 29 weeks, at which time they were killed. Breast tissue sections were stained with hematoxylin and eosin for histopathological assessments, and incidence and size of macroscopic mammary tumors were assessed. Cell proliferation (Ki-67 staining), apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick-labeling), and neoangiogenesis (CD31 staining) were determined in tumor sections. Plasma levels of transthyretin were measured in treated and control mice. Expression of proteins in mammary tumor sections was determined by immunohistochemistry. Proteomic profiling was performed by two-dimensional gel electrophoresis followed by mass spectrometry. All statistical tests were two-sided.

RESULTS

Administration of PEITC for 29 weeks was associated with 53.13% decreased incidence of macroscopic mammary tumors (mean tumor incidence, PEITC-supplemented diet vs control diet, 18.75% vs 40.00%, difference = -21.25%, 95% confidence interval [CI] = -43.19% to 0.69%, P = .07) and with a 56.25% reduction in microscopic mammary carcinoma lesions greater than 2 mm(2) (mean incidence, PEITC-supplemented diet vs control diet, 18.75% vs 42.86%, difference = -24.11%, 95% CI = -46.35% to -1.86%, P = .04). PEITC-mediated mammary cancer growth inhibition was not because of suppression of human epidermal growth factor receptor-2 expression but was associated with reduced cellular proliferation and neoangiogenesis, increased apoptosis, and altered expression of several proteins, including decreased ATP synthase in the tumor and increased plasma levels of transthyretin.

CONCLUSIONS

PEITC inhibits the growth of mammary cancers in a mouse model with similarities to human breast cancer progression. ATP synthase and transthyretin appear to be novel biomarkers associated with PEITC exposure.

Phenethyl isothiocyanate suppresses inhibitor of apoptosis family protein expression in prostate cancer cells in culture and in vivo

BACKGROUND

Cruciferous vegetable constituent phenethyl isothiocyanate (PEITC) causes apoptosis in prostate cancer cells through mechanisms not fully understood. The present study was designed to determine the role of inhibitor of apoptosis (IAP) family proteins in PEITC-induced apoptosis induction.

METHODS

Effect of PEITC treatment on protein and mRNA expression of IAP in cells was determined by Western blotting and reverse transcription PCR, respectively. Immunohistochemistry was performed to determine the in vivo effect of PEITC administration on X-linked IAP (XIAP) and Survivin protein expression. Overexpression of desired protein was achieved by transient transfection. Cell viability was determined by trypan blue dye exclusion assay, whereas apoptosis was quantified by measurement of histone-associated DNA fragment release into the cytosol. Transwell chamber assay was used to determine cell migration.

RESULTS

Exposure of PC-3 and LNCaP human prostate cancer cells to PEITC resulted in downregulation of XIAP and Survivin proteins and Survivin mRNA. PEITC administration to transgenic adenocarcinoma of mouse prostate mice caused modest but significant downregulation of XIAP and Survivin proteins in the dorsolateral prostate. Proapoptotic response to PEITC was significantly attenuated by ectopic expression of XIAP and Survivin proteins. Survivin overexpression also conferred modest but significant protection against PEITC-mediated inhibition of PC-3 cell migration.

CONCLUSIONS

The present study demonstrates that cellular responses to PEITC, including apoptosis induction and inhibition of cell migration, in prostate cancer cells are mediated by downregulation of XIAP and/or Survivin, which may serve as valid biomarkers of PEITC response in future clinical investigations.

Cancer chemoprevention with dietary isothiocyanates mature for clinical translational research

Inverse association between dietary intake of cruciferous vegetables and cancer risk observed in population-based case-control studies is partly attributable to structurally simple but mechanistically complex phytochemicals with an isothiocyanate (-N=C=S) functional group. Cancer protective role for dietary isothiocyanates (ITCs) is substantiated by preclinical studies in rodent models. A common feature of many naturally occurring ITCs relates to their ability to cause growth arrest and cell death selectively in cancer cells. At the same time, evidence continues to accumulate to suggest that even subtle change in chemical structure of the ITCs can have a profound effect on their activity and mechanism of action. Existing mechanistic paradigm stipulates that ITCs may not only prevent cancer initiation by altering carcinogen metabolism but also inhibit post-initiation cancer development by suppressing many processes relevant to tumor progression, including cellular proliferation, neoangiogenesis, epithelial-mesenchymal transition, and self-renewal of cancer stem cells. Moreover, the ITCs are known to suppress diverse oncogenic signaling pathways often hyperactive in human cancers (e.g. nuclear factor-κB, hormone receptors, signal transducer and activator of transcription 3) to elicit cancer chemopreventive response. However, more recent studies highlight potential adverse effect of Notch activation by ITCs on their ability to inhibit migration of cancer cells. Mechanisms underlying ITC-mediated modulation of carcinogen metabolism, growth arrest, and cell death have been reviewed extensively. This article provides a perspective on bench-cage-bedside evidence supporting cancer chemopreventive role for some of the most promising ITCs. Structure-activity relationship and mechanistic complexity in the context of cancer chemoprevention with ITCs is also highlighted.

Effect of tea, coffee and turmeric solutions on the colour of denture base acrylic resin: an in vitro study

Discoloration of acrylic resin denture base when it comes in contact with various food materials and beverages in the oral cavity may cause aesthetic concern to a denture wearer. The objective of this study was to evaluate the effect of tea, coffee and turmeric solutions on the colour of different brands of heat cure acrylic resin denture base materials commonly used in India. Spectrophotometer was used to evaluate the colour change. A significant difference was found when change in colour was statistically analysed.

D,L-sulforaphane-induced apoptosis in human breast cancer cells is regulated by the adapter protein p66Shc

Cancer chemopreventive response to D,L-sulforaphane (SFN), a synthetic racemic analogue of broccoli constituent L-sulforaphane, is partly attributable to apoptosis induction, but the mechanism of cell death is not fully understood. The present study demonstrates a critical role for adapter protein p66(Shc) in SFN-induced apoptosis. Immortalized mouse embryonic fibroblasts (MEF) derived from p66(shc) knockout mice were significantly more resistant to SFN-induced apoptosis, collapse of mitochondrial membrane potential, and reactive oxygen species (ROS) production compared with MEF obtained from the wild-type mice. Notably, a spontaneously immortalized and non-tumorigenic human mammary epithelial cell line (MCF-10A) was resistant to SFN-induced ROS production and apoptosis. Stable overexpression of manganese superoxide dismutase in MCF-7 and MDA-MB-231 human breast cancer cells conferred near complete protection against SFN-induced apoptosis and mitochondrial membrane potential collapse. SFN treatment resulted in increased S36 phosphorylation and mitochondrial translocation of p66(shc) in MDA-MB-231 and MCF-7 cells, and SFN-induced apoptosis was significantly attenuated by RNA interference of p66(shc) in both cells. SFN-treated MDA-MB-231 and MCF-7 cells also exhibited a marked decrease in protein level of peptidyl prolyl isomerase (Pin1), which is implicated in mitochondrial translocation of p66(shc) . However, stable overexpression of Pin1 failed to alter proapoptotic response to SFN at least in MCF-7 cells. Finally, SFN-induced S36 phosphorylation of p66(Shc) was mediated by protein kinase Cβ (PKCβ), and pharmacological inhibition of PKCβ significantly inhibited apoptotic cell death resulting from SFN exposure. In conclusion, the present study provides new insight into the mechanism of SFN-induced apoptosis involving PKCβ -mediated S36 phosphorylation of p66(shc).

Genotype profiles of Mycobacterium avium subspecies paratuberculosis recovered from suspected and Crohn's disease patients in India

Present study aimed to genotype Mycobacterium avium subspecies paratuberculosis (MAP) recovered from suspected and Crohn' s disease patients. A total of 32 MAP and DNA (directly from clinical samples) recovered from human origin were genotyped using IS 1311 PCR-REA. Isolates were cultured from stool, biopsies and blood clots of Crohn's disease patients, and stool samples of suspected (animal attendants, lab workers etc). Of the 32 MAP isolates belonging to 28 human beings, majority (84.3%) were genotyped as 'Bison type', while 21.7% were of 'cattle' and none was 'sheep' genotype. Study first time reports distribution of 'Cattle' and 'Bison type' 'genotypes in suspected and Crohn's patients on pilot scale in India. 'Bison type' genotype was predominant in the surveyed human population.

Abstract 565: Benzyl isothiocyanate-mediated inhibition of epithelial-mesenchymal transition in human breast cancer cells is associated with downregulation of urokinase-type plasminogen activator and its receptor

Novel approaches for chemoprevention of breast cancer are clinically attractive not only because many risk factors associated with this disease are not easily modifiable (e.g., genetic predisposition) but also due to the fact that the currently available chemopreventive options targeted against breast cancer (e.g., estrogen receptor antagonists) are sub-optimal and plagued with adverse side effects. Needless to emphasize that breast cancer continues to be a leading cause of cancer-related death in American women despite significant advances towards targeted therapies. Benzyl isothiocyanate (BITC), a constituent of edible cruciferous vegetables (e.g., garden cress), seems promising for chemoprevention of breast cancer based on our own preclinical work. For example, we have shown previously that BITC administration not only inhibits growth of human breast cancer xenografts (MDA-MB-231) in athymic mice but also imparts significant protection against mammary cancer development in a transgenic mouse model (MMTV-neu). More recent studies from our laboratory have revealed that BITC is a potent inhibitor of epithelial-mesenchymal transition (EMT) in human breast cancer cells, but the mechanism underlying this effect is not known. In the present study, we addressed this question using MDA-MB-231, MDA-MB-468, and SUM159 human breast cancer cells as a model. Overexpression of superoxide dismutase, which confers significant protection against proapoptotic and proautophagic cell death responses to BITC, did not have any meaningful impact on BITC-mediated inhibition of EMT. Likewise, ectopic expression of constitutively active STAT3, a transcription factor implicated in EMT regulation, had no effect on EMT inhibition by BITC. Instead, the BITC-mediated inhibition of EMT was associated with suppression of protein and mRNA levels of urokinase-type plasminogen activator (uPA) and its receptor (uPAR). Secretion of uPA in culture media of breast cancer cells was also decreased significantly upon BITC treatment. BITC-mediated inhibition of MDA-MB-231 xenograft growth in vivo was accompanied by downregulation of uPA and uPAR protein expression in the tumor and suppression of uPA secretion in plasma. Ectopic expression of uPAR in MDA-MB-468 and MCF-7 cells conferred partial but significant protection against BITC-mediated inhibition of EMT, cell migration, and/or cell invasion. Collectively, these results indicate that BITC-mediated inhibition of EMT is caused, at least in part, by suppression of the uPA/uPAR system. This investigation was supported by the USPHS grant RO1 CA129347-05, awarded by the National Cancer Institute.

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 565. doi:1538-7445.AM2012-565