Anahid Ehteda

Bromelain and N-acetylcysteine inhibit proliferation and survival of gastrointestinal cancer cells in vitro: significance of combination therapy

BackgroundBromelain and N-acetylcysteine are two natural, sulfhydryl-containing compounds with good safety profiles which have been investigated for their benefits and application in health and disease for more than fifty years. As such, the potential values of these agents in cancer therapy have been variably reported in the literature. In the present study, the efficacy of bromelain and N-acetylcysteine in single agent and combination treatment of human gastrointestinal carcinoma cells was evaluated in vitro and the underlying mechanisms of effect were explored.MethodsThe growth-inhibitory effects of bromelain and N-acetylcysteine, on their own and in combination, on a panel of human gastrointestinal carcinoma cell lines, including MKN45, KATO-III, HT29-5F12, HT29-5M21 and LS174T, were assessed by sulforhodamine B assay. Moreover, the influence of the treatment on the expression of a range of proteins involved in the regulation of cell cycle and survival was investigated by Western blot. The presence of apoptosis was also examined by TUNEL assay.ResultsBromelain and N-acetylcysteine significantly inhibited cell proliferation, more potently in combination therapy. Drug-drug interaction in combination therapy was found to be predominantly synergistic or additive. Mechanistically, apoptotic bodies were detected in treated cells by TUNEL assay. Furthermore, Western blot analysis revealed diminution of cyclins A, B and D, the emergence of immunoreactive subunits of caspase-3, caspase-7, caspase-8 and cleaved PARP, withering or cleavage of procaspase-9, overexpression of cytochrome c, reduced expression of anti-apoptotic Bcl-2 and pro-survival phospho-Akt, the emergence of the autophagosomal marker LC3-II and deregulation of other autophagy-related proteins, including Atg3, Atg5, Atg7, Atg12 and Beclin 1. These results were more prominent in combination therapy.ConclusionWe report for the first time to our knowledge the growth-inhibitory and cytotoxic effects of bromelain and N-acetylcysteine, in particular in combination, on a panel of gastrointestinal cancer cell lines with different phenotypes and characteristics. These effects apparently resulted from cell cycle arrest, apoptosis and autophagy. Towards the development of novel strategies for the enhancement of microscopic cytoreduction, our results lay the basis for further evaluation of this formulation in locoregional approaches to peritoneal surface malignancies and carcinomatosis.

Pre-Clinical Study of Panobinostat in Xenograft and Genetically Engineered Murine Diffuse Intrinsic Pontine Glioma Models

Background Diffuse intrinsic pontine glioma (DIPG), or high-grade brainstem glioma (BSG), is one of the major causes of brain tumor-related deaths in children. Its prognosis has remained poor despite numerous efforts to improve survival. Panobinostat, a histone deacetylase inhibitor, is a targeted agent that has recently shown pre-clinical efficacy and entered a phase I clinical trial for the treatment of children with recurrent or progressive DIPG. Methods A collaborative pre-clinical study was conducted using both a genetic BSG mouse model driven by PDGF-B signaling, p53 loss, and ectopic H3.3-K27M or H3.3-WT expression and an H3.3-K27M orthotopic DIPG xenograft model to confirm and extend previously published findings regarding the efficacy of panobinostat in vitro and in vivo. Results In vitro, panobinostat potently inhibited cell proliferation, viability, and clonogenicity and induced apoptosis of human and murine DIPG cells. In vivo analyses of tissue after short-term systemic administration of panobinostat to genetically engineered tumor-bearing mice indicated that the drug reached brainstem tumor tissue to a greater extent than normal brain tissue, reduced proliferation of tumor cells and increased levels of H3 acetylation, demonstrating target inhibition. Extended consecutive daily treatment of both genetic and orthotopic xenograft models with 10 or 20 mg/kg panobinostat consistently led to significant toxicity. Reduced, well-tolerated doses of panobinostat, however, did not prolong overall survival compared to vehicle-treated mice. Conclusion Our collaborative pre-clinical study confirms that panobinostat is an effective targeted agent against DIPG human and murine tumor cells in vitro and in short-term in vivo efficacy studies in mice but does not significantly impact survival of mice bearing H3.3-K27M-mutant tumors. We suggest this may be due to toxicity associated with systemic administration of panobinostat that necessitated dose de-escalation.

Combination of Albendazole and 2-Methoxyestradiol significantly improves the survival of HCT-116 tumor-bearing nude mice

BackgroundAlbendazole (ABZ) is a microtubule-targeting anthelmintic with a remarkable activity against a variety of human cancer cells. In this study, we examined if the antitumor activity of ABZ could be enhanced by its combination with other microtubule-binding agents.MethodsThe interactions between ABZ and microtubule-binding agents, paclitaxel, vinblastine, colchicine, and 2-methoxyestradiol were characterized using median effect analysis method in HCT-116 colorectal cancer cells and DU145 prostate cancer cell line. The mechanism underlying the synergistic interaction related to tubulin polymerization and apoptosis was then investigated. Finally, the effect of the combination therapy on the survival of HCT-116 tumor-bearing nude mice was evaluated.ResultsAmong the tested drugs, a synergistic anti-proliferative effect was observed with the combination of low concentrations of ABZ plus colchicine and ABZ plus 2-methoxyestradiol (2ME). Exploring the mechanism of the interaction between ABZ and 2ME revealed that the combination therapy synergistically activated the extrinsic pathway of apoptosis. Consistent with in vitro results, the combination of low concentration of ABZ with 2ME prolonged the survival of mice-bearing HCT-116 tumors. High concentration of ABZ in combination with 2ME, however, proved to be less effective than ABZ alone.ConclusionsThe combination of low doses of ABZ and 2ME has shown promising results in our pre-clinical model. Additionally, the finding that the combination of two microtubule-binding agents that share the same binding site can act synergistically may lead to the development of new therapeutic strategies in cancer treatment.

Cytotoxic effects of bromelain in human gastrointestinal carcinoma cell lines (MKN45, KATO-III, HT29-5F12, and HT29-5M21)

Background Bromelain is a pineapple stem extract with a variety of therapeutic benefits arising from interaction with a number of different biological processes. Several preclinical studies and anecdotal clinical observations have reported the anticancer properties of bromelain. In the present study, we investigated the cytotoxic effects of bromelain in four human cancer cell lines of gastrointestinal origin and the mechanisms involved. Methods The gastric carcinoma cell lines (KATO-III and MKN45) and two chemoresistant subpopulations of the HT29 colon adenocarcinoma cell line (HT29-5M21 and HT29-5F12) were treated with a range of concentrations of bromelain, as well as with cisplatin as a positive control. The effect of bromelain on the growth and proliferation of cancer cells was determined using a sulforhodamine B assay after 72 hours of treatment. Expression of apoptosis-associated proteins in MKN45 cells treated with bromelain was analyzed by Western blotting. Results Data from our sulforhodamine B assay showed that bromelain inhibited proliferation of HT29-5F12, HT29-5M21, MKN45, and KATO-III cells, with respective half maximal inhibitory concentration values of 29, 34, 94, and 142 μg/mL. Analyzing the expression of proapoptotic and antiapoptotic proteins in bromelain-treated MKN45 cells, we observed activation of the caspase system, cleavage of PARP and p53, overexpression of cytochrome C, attenuation of phospho-Akt and Bcl2, and removal of MUC1. Apart from the caspase-dependent apoptosis observed, emergence of cleaved p53 supports a direct, extranuclear apoptotic function of p53. Moreover, interrupted Akt signaling and attenuation of Bcl2 and MUC1 oncoproteins suggest impaired survival of cancer cells. Conclusion Our findings collectively indicate that bromelain exerts cytotoxic effects in a panel of human gastric and colon carcinoma cells. Our study of MKN45 cells implicated different mechanisms in bromelain-induced cell death. While promoting apoptosis with involvement of the caspase system and extranuclear p53, bromelain also appears to impair cancer cell survival by blocking the Akt pathway and attenuating Bcl2 and MUC1 oncoproteins.

Depletion of mucin in mucin-producing human gastrointestinal carcinoma: Results from in vitro and in vivo studies with bromelain and N-acetylcysteine

Aberrant expression of membrane-associated and secreted mucins, as evident in epithelial tumors, is known to facilitate tumor growth, progression and metastasis, and to provide protection against adverse growth conditions, chemotherapy and immune surveillance. Emerging evidence provides support for the oncogenic role of MUC1 in gastrointestinal carcinomas and relates its expression to an invasive phenotype. Similarly, mucinous differentiation of gastrointestinal tumors, in particular increased or de novo expression of MUC2 and/or MUC5AC, is widely believed to imply an adverse clinicopathological feature. Through formation of viscous gels, too, MUC2 and MUC5AC significantly contribute to the biology and pathogenesis of mucin-secreting gastrointestinal tumors. Here, we investigated the mucin-depleting effects of bromelain (BR) and N-acetylcysteine (NAC), in nine different regimens as single or combination therapy, in in vitro (MKN45, KATOIII and LS174T cell lines) and in vivo (female nude mice bearing intraperitoneal MKN45 and LS174T) settings. The inhibitory effects of the treatment on cancer cell growth and proliferation were also evaluated in vivo. Our results suggest that a combination of BR and NAC with dual effects on growth and mucin products of mucin-expressing tumor cells is a promising candidate towards the development of novel approaches to gastrointestinal malignancies with the involvement of mucin pathology. This capability supports the use of this combination formulation in locoregional approaches for reducing the adverse effects of the aberrantly secreted gel-forming mucins, as in pseudomyxoma peritonei and similar pathologies with ectopic production of mucin.

Anticancer effect of bromelain with and without cisplatin or 5-FU on malignant peritoneal mesothelioma cells.

Malignant peritoneal mesothelioma (MPM) is a rare neoplasm of the peritoneum, causally related to asbestos exposure. Nonspecific symptoms with a late diagnosis results in poor survival (<1 year). Treatment with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy has improved survival in some patients (median 3–5 years). Hence, new therapies are urgently needed. MUC1 is a glycosylation-dependent protein that confers tumours with invasiveness, metastasis and chemoresistance. Bromelain (cysteine proteinase) hydrolyses glycosidic bonds. Therefore, we investigated the antitumour effect of bromelain on MUC1-expressing MPM cell lines. MUC1 expressions in cells were assessed using immunofluorescent probes with cells grown on cover slips and western blot analysis on cell lysates. The cell lines were treated with various concentrations of bromelain and after 4 and 72 h, their viability was assessed using standard sulforhodamine assays. The cells were also treated with combinations of bromelain and cytotoxic drugs (cisplatin or 5-FU) and their viability was assessed at 72 h. Finally, with western blotting, the effects of bromelain on cellular survival proteins were investigated. PET cells expressed more MUC1 compared with YOU cells. The cell viability of both PET and YOU cells was adversely affected by bromelain, with PET cells being slightly resistant. The addition of bromelain increased the cytotoxicity of cisplatin significantly in both cell lines. However, 5-FU with bromelain did not show any significant increase in cytotoxicity. Bromelain-induced cell death is by apoptosis and autophagy. Bromelain has the potential of being developed as a therapeutic agent in MPM.

The expression of the Sprouty 1 protein inversely correlates with growth, proliferation, migration and invasion of ovarian cancer cells

BackgroundOur recent study on a panel of human ovarian cancer cells revealed that SKOV-3 cells barely express the Sprouty isoform 1 (Spry1) while 1A9 cells maintain it at a level similar to normal ovarian cells. Here we investigated the functional outcomes of induced alterations in the expression of Spry1 in the two cell lines in vitro.MethodsUsing the Spry1 specific plasmid and siRNA, the expression of Spry1 was induced and conversely silenced in SKOV-3 and 1A9 cells, respectively. The functional outcome was investigated by means of proliferation, MTT, scratch-wound, migration and invasion assays and selection of the stable clones. Mechanism of the effect was explored by Western blot.ResultsIn the Spry1-transfected SKOV-3 cells, a significant reduction in growth and proliferation was evident. Stable clones of the Spry1-transfected SKOV-3 were almost undetectable after day 14. The number of migrated and invaded cells and the percentage of the scratch closure were significantly lower in the Spry1-transfected group. Spry1 silencing in 1A9 cells, on the other hand, led to a significant increase in cell growth and proliferation. The number of migrated and invaded cells and the percentage of the scratch closure significantly increased in Spry1-silenced 1A9 group. Mechanistically, overexpression of Bax, activation of caspases 3, 7, 8 and 9, cleavage of PARP and attenuation of Bcl-2 and Bcl-xl were observed along with reduced activation of Erk and Akt and increased amount and activity of PTEN in the Spry1-transfected SKOV-3 cells.ConclusionsHere, we report the inverse correlation between the expression of Spry1 and growth, proliferation, invasion and migration of ovarian cancer cells.

Dual targeting of mitochondrial function and mTOR pathway as a therapeutic strategy for diffuse intrinsic pontine glioma

Diffuse Intrinsic Pontine Gliomas (DIPG) are the most devastating of all pediatric brain tumors. They mostly affect young children and, as there are no effective treatments, almost all patients with DIPG will die of their tumor within 12 months of diagnosis. A key feature of this devastating tumor is its intrinsic resistance to all clinically available therapies. It has been shown that glioma development is associated with metabolic reprogramming, redox state disruption and resistance to apoptotic pathways. The mitochondrion is an attractive target as a key organelle that facilitates these critical processes. PENAO is a novel anti-cancer compound that targets mitochondrial function by inhibiting adenine nucleotide translocase (ANT). Here we found that DIPG neurosphere cultures express high levels of ANT2 protein and are sensitive to the mitochondrial inhibitor PENAO through oxidative stress, while its apoptotic effects were found to be further enhanced upon co-treatment with mTOR inhibitor temsirolimus. This combination therapy was found to act through inhibition of PI3K/AKT/mTOR pathway, HSP90 and activation of AMPK. In vivo experiments employing an orthotopic model of DIPG showed a marginal anti-tumour effect likely due to poor penetration of the inhibitors into the brain. Further testing of this anti-DIPG strategy with compounds that penetrate the BBB is warranted.

Anti-Tumour and Chemosensitising Effect of a Combination of Bromelain + N-Acetyl Cysteine with Cisplatin or 5-Fu on Malignant Peritoneal Mesothelioma Cells

normally poor however, cytoreductive surgery and hyperthermic intraperitoneal chemotherapy has increased survival in some patients. Hence, new therapies are needed. MUC1 is a glycosylation dependant protein associated with tumour invasiveness, metastasis and chemo resistance. Bromelain, a cysteine proteinase, hydrolyses glycosidic bonds, whilst N-Acetyl cysteine reduces disulphide bonds in glycoprotein. Hence, we investigated the anti-tumour effect of these agents in MUC 1 expressing MPM cell lines. Materials and Methods: The cell lines were treated to various concentrations of bromelain, NAC and combinations of NAC + bromelain, NAC + bromelain + cisplatin or 5-FU. Their cell viabilities were assessed at 48 hours with sulfhordamine B assay. Finally, with western blotting, the effect of NAC and the combination of NAC + bromelain on cellular survival proteins were investigated. Results: Combination of NAC (10 mM) with bromelain (75 ug/ml) showed 97% and 88% cell proliferation inhibition in YOU and PET cells, respectively. In triple combination, the addition of cisplatin to only 5.0 mM NAC and bromelain increased cytotoxicity in YOU cells but absent at 10.0 mM NAC concentration. However, in PET cells, triple combinations with cisplatin had no effect. The addition of 5-FU in triple combinations showed an increase in cytotoxicity with 5.0 mM NAC and bromelain in YOU cells. No increase in cytotoxicity was seen with addition of 10 mM NAC. In PET cells, the addition 5-FU to 5.0 mM NAC + 50 ug/ml bromelain, enhanced cytotoxicity significantly but was absent at all other combinations. Conclusion: The combination of bromelain and NAC may be developed as anti-tumour agents for treating MPM, with a possible role in combined therapy with current chemotherapeutic agents.

Abstract LB-007: Synergistic inhibition of human gastric and colorectal cancers by Bromelain and N-acetylcysteine: An in vivo study

Mucin is well understood to be an adverse prognostic factor in some cancers. We previously reported that a combination of Bromelain (BR) and N-acetylcysteine (NAC) were synergistic in dissolving pseudomyxoma peritonei mucin, had direct in vitro cytotoxic effects on some gastrointestinal cancer cells and sensitized them to some chemotherapy agents. In the present study, we aimed to evaluate the growth-inhibitory effect of BR and NAC as single agent or combination therapy in nude mice models of gastrointestinal cancer. Nude mice received 2 million and 1 million cells of MKN45 (gastric) and LS174T (colorectal) by intraperitoneal injection. At day 14 and 7 post inoculation for MKN45 and LS174T cells, respectively, animals were intraperitoneally administrated BR (3, 6 mg/kg), NAC (300, 500 mg/kg) or their combination every other day over 12 days for MKN45 and 17 days for LS174T models. At the end of the study, the animals were euthanized, the number of peritoneal nodules and their weight were collected, and the peritoneal tumors were subjected to immunohistochemistry for evaluation of MUC2. No toxicity was observed during the experiment. At necropsy, highly significant reductions in the number of tumor nodules and tumor burden were observed, in particular in the combination group, where almost complete inhibition in LS174T group was found. There was more than 95% and 70% decreases in tumor burden and tumor nodules, respectively, in LS174T group after combination treatment. For MKN45 model, the reductions in tumor burden and tumor nodules in combination groups were more than 60% and 70%, respectively. Performing immunohistochemistry on tumor samples, MUC2 staining of the LS174T xenografts showed a greater than 60% reduction of cytoplasmic staining. To the best of our knowledge, this is the first report of the in vivo use of this combination with synergistic inhibition of human gastric and colorectal cancers. The combination of BR and NAC in mucin secreting gastrointestinal tumors is interesting and could be of potential value in peritoneal cancer. Citation Format: Afshin Amini, Samar Masoumi-Moghaddam, Anahid Ehteda, Winston Liauw, Javed Akhter, Krishna Pilai, David L. Morris. Synergistic inhibition of human gastric and colorectal cancers by Bromelain and N-acetylcysteine: An in vivo study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-007. doi:10.1158/1538-7445.AM2015-LB-007