Jheelam Banerjee

Chronic nicotine inhibits the therapeutic effects of gemcitabine on pancreatic cancer in vitro and in mouse xenografts

AIM OF STUDY Smoking is an established risk factor for pancreatic cancer and nicotine replacement therapy (NRT) often accompanies chemotherapy. The current study has tested the hypothesis that chronic exposure to low dose nicotine reduces the responsiveness of pancreatic cancer to the leading therapeutic for this cancer, gemcitabine. METHODS The effects of chronic nicotine (1 μm/L) on two pancreatic cancer cell lines in vitro and in a xenograft model were assessed by immunoassays, Western blots and cell proliferation assays. RESULTS Exposure in vitro to nicotine for 7 days inhibited the gemcitabine-induced reduction in viable cells, gemcitabine-induced apoptosis as indicated by reduced expression of cleaved caspase-3 while inducing the phosphorylation of signalling proteins extracellular signal-regulated kinase (ERK), v-akt thymoma viral oncogene homolog (protein kinase B, AKT) and Src. Nicotine (1 μm/L) in the drinking water for 4 weeks significantly reduced the therapeutic response of mouse xenografts to gemcitabine while reducing the induction of cleaved caspase-3 and the inhibition of phosphorylated forms of multiple signalling proteins by gemcitabine in xenograft tissues. CONCLUSIONS Our experimental data suggest that continued moderate smoking and NRT may negatively impact therapeutic outcomes of gemcitabine on pancreatic cancer and that clinical studies in cancer patients are now warranted.

Nicotine induces self-renewal of pancreatic cancer stem cells via neurotransmitter-driven activation of sonic hedgehog signalling.

A small subpopulation of pancreatic cancer cells with characteristics of stem cells drive tumour initiation, progression and metastasis. A better understanding of the regulation of cancer stem cells may lead to more effective cancer prevention and therapy. We have shown that the proliferation and migration of pancreatic cancer cell lines is activated by the nicotinic receptor-mediated release of stress neurotransmitters, responses reversed by γ-aminobutyric acid (GABA). However, the observed cancer inhibiting effects of GABA will only succeed clinically if GABA inhibits pancreatic cancer stem cells (PCSCs) in addition to the more differentiated cancer cells that comprise the majority of cancer tissues and cell lines. Using PCSCs isolated from two pancreatic cancer patients by cell sorting and by spheroid formation assay from pancreatic cancer cell line Panc-1, we tested the hypothesis that nicotine induces the self-renewal of PCSCs. Nicotinic acetylcholine receptors (nAChRs) α3, α4, α5 and α7 were expressed and chronic exposure to nicotine increased the protein expression of these receptors. Immunoassays showed that PCSCs produced the stress neurotransmitters epinephrine and norepinephrine and the inhibitory neurotransmitter GABA. Chronic nicotine significantly increased the production of stress neurotransmitters and sonic hedgehog (SHH) while inducing Gli1 protein and decreasing GABA. GABA treatment inhibited the induction of SHH and Gli1. Spheroid formation and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide assays showed significant nicotine-induced increases in self renewal and cell proliferation, responses blocked by GABA. Our data suggest that nicotine increases the SHH-mediated malignant potential of PCSCs and that GABA prevents these effects.

Differential modulation of nicotine-induced gemcitabine resistance by GABA receptor agonists in pancreatic cancer cell xenografts and in vitro

BackgroundPancreatic cancer is frequently resistant to cancer therapeutics. Smoking and alcoholism are risk factors and pancreatic cancer patients often undergo nicotine replacement therapy (NRT) and treatment for alcohol dependence. Based on our report that low dose nicotine within the range of NRT causes gemcitabine resistance in pancreatic cancer, our current study has tested the hypothesis that GABA or the selective GABA-B-R agonist baclofen used to treat alcohol dependence reverse nicotine-induced gemcitabine resistance in pancreatic cancer.MethodsUsing mouse xenografts from the gemcitabine--sensitive pancreatic cancer cell line BXPC-3, we tested the effects of GABA and baclofen on nicotine-induced gemcitabine resistance. The levels of cAMP, p-SRC, p-ERK, p-AKT, p-CREB and cleaved caspase-3 in xenograft tissues were determined by ELISA assays. Expression of the two GABA-B receptors, metalloproteinase-2 and 9 and EGR-1 in xenograft tissues was monitored by Western blotting. Mechanistic studies were conducted in vitro, using cell lines BXPC-3 and PANC-1 and included analyses of cAMP production by ELISA assay and Western blots to determine protein expression of GABA-B receptors, metalloproteinase-2 and 9 and EGR-1.ResultsOur data show that GABA was as effective as gemcitabine and significantly reversed gemcitabine resistance induced by low dose nicotine in xenografts whereas baclofen did not. These effects of GABA were accompanied by decreases in cAMP, p-CREB, p-AKT, p-Src, p-ERK metalloproteinases-9 and -2 and EGR-1 and increases in cleaved caspase-3 in xenografts whereas baclofen had the opposite effects. In vitro exposure of cells to single doses or seven days of nicotine induced the protein expression of MMP-2, MMP-9 and EGR-1 and these responses were blocked by GABA. Baclofen downregulated the protein expression of GABA-B-Rs in xenograft tissues and in cells exposed to baclofen for seven days in vitro. This response was accompanied by inversed baclofen effects from inhibition of cAMP formation after single dose exposures to stimulation of cAMP formation in cells pretreated for seven days.ConclusionsThese findings suggest GABA as a promising single agent for the therapy of pancreatic cancer and to overcome nicotine-induced gemcitabine resistance whereas treatment with baclofen may increase gemcitabine resistance.

Regulation of nonsmall-cell lung cancer stem cell like cells by neurotransmitters and opioid peptides

Nonsmall‐cell lung cancer (NSCLC) is the leading type of lung cancer and has a poor prognosis. We have shown that chronic stress promoted NSCLC xenografts in mice via stress neurotransmitter‐activated cAMP signaling downstream of beta‐adrenergic receptors and incidental beta‐blocker therapy was reported to improve clinical outcomes in NSCLC patients. These findings suggest that psychological stress promotes NSCLC whereas pharmacologically or psychologically induced decreases in cAMP may inhibit NSCLC. Cancer stem cells are thought to drive the development, progression and resistance to therapy of NSCLC. However, their potential regulation by stress neurotransmitters has not been investigated. In the current study, epinephrine increased the number of cancer stem cell like cells (CSCs) from three NSCLC cell lines in spheroid formation assays while enhancing intracellular cAMP and the stem cell markers sonic hedgehog (SHH), aldehyde dehydrogenase‐1 (ALDH‐1) and Gli1, effects reversed by GABA or dynorphin B via Gαi‐mediated inhibition of cAMP formation. The growth of NSCLC xenografts in a mouse model of stress reduction was significantly reduced as compared with mice maintained under standard conditions. Stress reduction reduced serum levels of corticosterone, norepinephrine and epinephrine while the inhibitory neurotransmitter γ‐aminobutyric acid (GABA) and opioid peptides increased. Stress reduction significantly reduced cAMP, VEGF, p‐ERK, p‐AKT, p‐CREB, p‐SRc, SHH, ALDH‐1 and Gli1 in xenograft tissues whereas cleaved caspase‐3 and p53 were induced. We conclude that stress neurotransmitters activate CSCs in NSCLC via multiple cAMP‐mediated pathways and that pharmacologically or psychologically induced decreases in cAMP signaling may improve clinical outcomes in NSCLC patients.

Prevention of pancreatic cancer in a hamster model by cAMP decrease

Smoking and alcoholism are risk factors for the development of pancreatitis-associated pancreatic ductal adenocarcinoma (PDAC). We have previously shown that these cancers overexpressed stress neurotransmitters and cyclic adenosine monophosphate (cAMP) while the inhibitory neurotransmitter γ-aminobutyric acid (GABA) was suppressed. Using a hamster model, the current study has tested the hypothesis that cAMP decrease by GABA supplementation in the drinking water prevents the development of pancreatitis-associated PDAC. Our data reveal strong preventive effects of GABA supplementation on the development of PDAC and pancreatic intraductal neoplasia (PanIN). ELISA assays and immunohistochemistry revealed significant decreases in the levels of cAMP and interleukin 6 accompanied by reductions in the expression of several cancer stem cell markers and phosphorylated signaling proteins, which stimulate cell proliferation, and migration in pancreatic exocrine cells of GABA treated animals. We conclude that cAMP decrease by GABA supplementation inhibits multiple cancer stimulating pathways in cancer stem cells, differentiated cancer cells and the immune system, identifying this approach as promising novel tool for the prevention of PDAC in individuals with a history of smoking and alcoholism.

Abstract 823: Prevention of pancreatic cancer by cAMP control

Smoking and alcoholism are risk factors for the development of pancreatitis-associated pancreatic ductal adenocarcinoma (PDAC). Using a hamster model of pancreatitis-associated PDAC induced by treatment with ethanol in the drinking water and the nicotine-derived nitrosamine 4-methylnitrosamino-(3-pyridyl)-1-butanone (NNK) by subcutaneous injection as well as immunohistochemistry of human PDAC tissue microarrays, we have previously shown that these cancers overexpressed stress neurotransmitters and cAMP while the inhibitory neurotransmitter a-aminobutyric acid (GABA) was suppressed. Using our hamster model, the current study has tested the hypothesis that cAMP control by GABA supplementation in the drinking water prevents the development of pancreatitis-associated PDAC. Our data reveal strong preventive effects of GABA supplementation on the development of PDAC and pancreatic intraductal neoplasia (PanIN). ELISA assays and immunohistochemistry revealed significant decreases in the levels of cyclic adenosine monophosphate (cAMP) and interleukin 6 accompanied by reductions in the expression of several cancer stem cell markers, phosphorylated signaling proteins associated with cell proliferation and migration in pancreatic exocrine cells of GABA treated animals. We conclude that cAMP control by GABA supplementation inhibits multiple cancer supporting pathways at the level of cancer stem cells, differentiated cancer cells and the immune system, identifying this approach as promising novel tool for the prevention of PDAC in individuals with a history of smoking and alcoholism. Citation Format: Jheelam Banerjee, Arokya M. Papu John, Mohammed H. Al-Wadei, Hildegard M. Schuller. Prevention of pancreatic cancer by cAMP control. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 823.

Abstract 3729: Inhibition of non small-cell lung cancer by stress reduction

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Non small-cell lung cancer (NSCLC) is the leading type of lung cancer with a poor prognosis. Smoking is a risk factor but NSCLC develops in a significant number of nonsmokers. We have reported that social stress significantly promoted the growth of NSCLC xenografts, a response mediated by multiple cAMP-driven signaling cascades downstream of Gαi-coupled beta-adrenergic receptors activated by the stress neurotransmitters norepinephrine and epinephrine and reversed by γ-aminobutyric acid (GABA) via Gαi-coupled GABA-B-receptor signaling. In addition, improved clinical outcomes in NSCLC patients with incidental beta-blocker therapy have been reported. These findings suggest that psychological stress with the associated increase in systemic stress neurotransmitter levels and suppression of physiological agonists for Gαi-coupled receptors may significantly contribute to the high incidence and poor therapeutic response of NSCLC. On the other hand, these findings suggest that stress reduction may have significant inhibitory effects on NSCLC. To test this hypothesis, we achieved stress reduction in athymic nude mice by maintaining the animals in larger cages and by providing them with several enrichment items, resulting in reduced systemic levels of corticosterone, norepinephrine and epinephrine while the levels of GABA and the physiological agonists for Gαi-coupled opioid receptors, dynorphin A and B and met-enkephalin increased. We found that stress reduction significantly inhibited the establishment of xenografts and significantly reduced xenograft sizes. Xenografts in the stress reduction group expressed lower levels of cAMP, VEGF and sonic hedgehog (SHH) accompanied by reduced protein expression of p-ERK, p-AKT, p-CREB, p-SRc and Gli1 while cleaved caspase-3 and p53 proteins were induced. Based on the observed reduction of the cancer stem cell markers SHH and Gli1 in xenograft tissues, we conducted additional mechanistic experiments with cancer stem cells enriched from three NSCLC cell lines under selective sphere formation conditions over 21 days with subcultures every seven days. We found that epinephrine significantly increased stem cell self renewal associated with increased intracellular cAMP, increased levels of the stem cell markers SHH and aldehyde dehydrogenase-1 and increased expression of Gli1. Simultaneous treatment of the enriched cancer stem cells with GABA or dynorphin B completely reversed all of these effects. We conclude that stress reduction can act as a powerful inhibitor of NSCLC by restoring cAMP homeostasis and should be incorporated as important component into existing NSCLC prevention and therapy protocols to improve clinical outcomes. Supported in part by 5RC1CA144640 and State of Tennessee Center of Excellence for Human and Livestock Disease Citation Format: Jheelam Banerjee, Arokya M. S Papu John, Hildegard M. Schuller. Inhibition of non small-cell lung cancer by stress reduction. [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 3729. doi:10.1158/1538-7445.AM2015-3729

Abstract 5298: Regulation of urothelial bladder cancer by nicotine and stress neurotransmitters

Urothelial bladder cancer (UBC) is the 7th most common cancer in men and the 17th most common cancer in women. Smoking is an established risk factor for UBC. However, the mechanisms how smoking induces bladder cancer are poorly understood. Using two established human urothelial bladder cancer cell lines, our data show that nicotine significantly increased the proliferation of both cell lines. Both cell lines produced the stress neurotransmitters norepinephrine and epinephrine and nicotine further enhanced this activity. The broad-spectrum beta-blocker propranolol strongly inhibited base level and nicotine-induced proliferation in both cell lines, identifying beta-adrenergic receptors as mediators. Proliferation in response to exogenous addition of epinephrine, norepinephrine or the selective β-adrenergic agonist isoproterenol and complete blockage of these responses by propranolol support this interpretation. Treatment with the inhibitory neurotransmitter γ-aminobutyric acid (GABA), that inhibits beta-adrenergic receptor-mediated proliferation of other cancer types via inhibition of cAMP formation, was less effective. These findings suggest that urothelial bladder cancer cells are stimulated in their growth via beta-adrenergic receptor signaling independent of cAMP by nicotine or psychological stress. Additional investigations are underway to further dissect the signal transduction pathways involved. Supported by the State of Tennessee Center of Excellence in Livestock Diseases and Human Health. Citation Format: Arokya M. Papu John, Jheelam Banerjee, Hildegard M. Schuller. Regulation of urothelial bladder cancer by nicotine and stress neurotransmitters. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5298. doi:10.1158/1538-7445.AM2014-5298

Abstract 1703: Nicotine-induced gemcitabine resistance is reversed by gamma-aminobutyric acid but enhanced by baclofen in pancreatic cancer xenografts and in pancreatic cancer cells in vitro

Pancreatic cancer is frequently resistant to cancer therapeutics. Smoking and alcoholism are risk factors and pancreatic cancer patients often undergo nicotine replacement therapy (NRT) and treatment for alcohol dependence. Based on our report that low dose nicotine within the range of NRT causes gemcitabine resistance in pancreatic cancer, our current study has tested the hypothesis that GABA or the selective GABA-B-R agonist baclofen used to treat alcohol dependence reverse nicotine-induced gemcitabine resistance in pancreatic cancer. Using pancreatic cancer cell lines BXPC-3 and PANC-1, our data show that GABA significantly reversed gemcitabine resistance induced by low dose nicotine in xenografts whereas baclofen did not. This effect of GABA was accompanied by decreases in cAMP, p-CREB, p-AKT, p-Src, p-ERK metalloproteinases-9 and -2 and EGR-1 and increases in cleaved caspase-3 in xenografts whereas baclofen had the opposite effects. In vitro exposure of cells to single doses or seven days of nicotine induced the protein expression of MMP-2, MMP-9 and EGR-1 and these responses were blocked by GABA. Baclofen downregulated the protein expression of GABA-B-Rs in xenograft tissues and in cells exposed to baclofen for seven days in vitro. This response was accompanied by inversed baclofen effects from inhibition of cAMP formation after single dose exposures to stimulation of cAMP formation in cells pretreated for seven days. These findings suggest GABA as a promising agent to overcome nicotine-induced gemcitabine resistance in pancreatic cancer whereas treatment of alcoholism by baclofen may increase gemcitabine resistance. Supported by grants RO1CA130888 and RO1CA042829 with the National Cancer Institute. Citation Format: Jheelam Banerjee, Hussein A. N Al-Wadei, Mohammed H. Al-Wadei, Koami Dagnon, Hildegard M. Schuller. Nicotine-induced gemcitabine resistance is reversed by gamma-aminobutyric acid but enhanced by baclofen in pancreatic cancer xenografts and in pancreatic cancer cells in vitro . [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1703. doi:10.1158/1538-7445.AM2014-1703

Abstract 2191: GABA but not baclofen prevents gemcitabine resistance induced by low dose nicotine in pancreatic cancer xenografts.

Pancreatic ductal adenocarinoma (PDAC) is a leading cause of cancer deaths in developed countries. The nucleoside analog Gemcitabine, which induces apoptosis, is widely used for the therapy of pancreatic cancer. Smoking and alcoholism are risk factors for pancreatic cancer. Nicotine replacement therapy often accompanies chemotherapy while the GABA-B receptor (GABA-B-R) agonist Baclofen has recently been suggested as an effective agent for the treatment of alcohol dependence. Our laboratory has shown that the proliferation and migration of PDAC and pancreatic duct epithelial cells in vitro is regulated by the nicotinic receptor-mediated synthesis and release of stress neurotransmitters that bind to beta-adrenoreceptors (beta-ARs). We have additionally shown that nicotine in the drinking water at a high dose (432 μmole/L) comparable to nicotine exposure in heavy smokers significantly stimulated the growth of PDAC xenografts whereas identical exposure of mice to low dose nicotine (1 μmole/L) reduced gemcitabine-induced apoptosis, thus significantly increasing resistance to gemcitabine. In the current study, we have investigated the potential prevention of nicotine-induced gemcitabine resistance by γ-aminobutyric acid (GABA) and Baclofen in PDAC xenografts. We found that GABA significantly reduced nicotine-induce drug resistance. By contrast, Baclofen failed to reduce nicotine-induced resistance to gemcitabine while even slightly increasing xenograft growth in mice not exposed to nicotine. Investigation of xenograft tissues for the expression levels of the GABA-B-R, intracellular cAMP and signaling proteins associated with cell proliferation, apoptosis and metastasis by immunoassays and western blots revealed effective inhibition of cAMP-dependent signaling in xenografts of mice treated with GABA. By contrast, Baclofen did not inhibit cAMP-dependent signaling and decreased the protein expression of the GABA-R, suggesting downregulation of the receptor. Our findings identify GABA as a promising agent for the prevention of nicotine-induced resistance to gemcitabine in PDAC. On the other hand, our data suggest that treatment of alcohol dependence by Baclofen should be avoided in PDAC patients. Supported by grants RO1CA130888 and RO1CA042829 with the National Cancer Institute. Citation Format: Jheelam Banerjee, Mohammed H. Al-Wadei, Hussein A. N. Al-Wadei, Hildegard M. Schuller. GABA but not baclofen prevents gemcitabine resistance induced by low dose nicotine in pancreatic cancer xenografts. [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 2191. doi:10.1158/1538-7445.AM2013-2191