Capsaicin Displays Anti-Proliferative Activity against Human Small Cell Lung Cancer in Cell Culture and Nude Mice Models via the E2F Pathway

Small cell lung cancer (SCLC) is characterized by rapid progression and low survival rates. Therefore, novel therapeutic agents are urgently needed for this disease. Capsaicin, the active ingredient of chilli peppers, displays anti-proliferative activity in prostate and epidermoid cancer in vitro. However, the anti-proliferative activity of capsaicin has not been studied in human SCLCs. The present manuscript fills this void of knowledge and explores the anti-proliferative effect of capsaicin in SCLC in vitro and in vivo.BrdU assays and PCNA ELISAs showed that capsaicin displays robust anti-proliferative activity in four human SCLC cell lines. Furthermore, capsaicin potently suppressed the growth of H69 human SCLC tumors in vivo as ascertained by CAM assays and nude mice models. The second part of our study attempted to provide insight into molecular mechanisms underlying the anti-proliferative activity of capsaicin. We found that the anti-proliferative activity of capsaicin is correlated with a decrease in the expression of E2F-responsive proliferative genes like cyclin E, thymidylate synthase, cdc25A and cdc6, both at mRNA and protein levels. The transcription factor E2F4 mediated the anti-proliferative activity of capsaicin. Ablation of E2F4 levels by siRNA methodology suppressed capsaicin-induced G1 arrest. ChIP assays demonstrated that capsaicin caused the recruitment of E2F4 and p130 on E2F-responsive proliferative promoters, thereby inhibiting cell proliferation.Our findings suggest that the anti-proliferative effects of capsaicin could be useful in the therapy of human SCLCs

The flavonoid nobiletin inhibits tumor growth and angiogenesis of ovarian cancers via the Akt pathway

Despite its importance, the death rate of ovarian cancer has remained unchanged over the past five decades, demanding an improvement in prevention and treatment of this malignancy. With no known carcinogens, targeted prevention is currently unavailable, and efforts in early detection of this malignancy by screening biomarkers have failed. The inhibition of angiogenesis, also known as angioprevention, is a promising strategy to limit the growth of solid tumors, including ovarian cancers. Nobiletin, a polymethoxy flavonoid compound isolated from the tiansheng plant, has been shown to inhibit the growth of multiple types of human cancers. However, there are no reports involving the effect on nobiletin on human ovarian cancer. The present report shows that nobiletin potently decreases the viability of ovarian cancer cells in vitro. However, nobiletin does not affect the viability of normal ovarian epithelial cells at \u3c40 µM. The antitumor activity of nobiletin was also observed in athymic mouse models and in chicken chorioallantoic membrane (CAM) models. The anti-neoplastic activity of nobiletin was due to its ability to inhibit angiogenesis. We also studied the molecular mechanisms by which nobiletin suppresses angiogenesis. We observed that nobiletin inhibits secretion of the key angiogenesis mediators, Akt, HIF-1α, NF-κB and vascular epithelial growth factor (VEGF) by ovarian cancer cells. Transient transfection experiments showed that nobiletin inhibits production of HIF-1α by downregulation of Akt. Such decreased levels of HIF-1α were responsible for nobiletin-induced suppression of VEGF. Our data suggest that nobiletin may be a promising anti-angiogenic agent relevant for therapy of ovarian cancers

Inhibition of Cholinergic Signaling Causes Apoptosis in Human Bronchioalveolar Carcinoma

Recent case-controlled clinical studies show that bronchioalveolar carcinomas (BAC) are correlated with smoking. Nicotine, the addictive component of cigarettes, accelerates cell proliferation through nicotinic acetylcholine receptors (nAChR). In this study, we show that human BACs produce acetylcholine (ACh) and contain several cholinergic factors including acetylcholinesterase (AChE), choline acetyltransferase (ChAT), choline transporter 1 (CHT1, SLC5A7), vesicular acetylcholine transporter (VAChT, SLC18A3), and nACh receptors (AChRs, CHRNAs). Nicotine increased the production of ACh in human BACs, and ACh acts as a growth factor for these cells. Nicotine-induced ACh production was mediated by α7-, α3β2-, and β3-nAChRs, ChAT and VAChT pathways. We observed that nicotine upregulated ChAT and VAChT. Therefore, we conjectured that VAChT antagonists, such as vesamicol, may suppress the growth of human BACs. Vesamicol induced potent apoptosis of human BACs in cell culture and nude mice models. Vesamicol did not have any effect on EGF or insulin-like growth factor-II–induced growth of human BACs. siRNA-mediated attenuation of VAChT reversed the apoptotic activity of vesamicol. We also observed that vesamicol inhibited Akt phosphorylation during cell death and that overexpression of constitutively active Akt reversed the apoptotic activity of vesamicol. Taken together, our results suggested that disruption of nicotine-induced cholinergic signaling by agents such as vesamicol may have applications in BAC therapy

1,3-Dipolar cycloadditions: Part VIII¹ - Microwave irradiation assisted synthesis of <i>N</i>-methyl-<i>C</i>-aryl nitrones

880-881N-Methyl-C-arylnitrones have been synthesized in very high yields within a few minutes from N-methyl-hydroxylamine hydrochloride and aryl aldehydes in presence of sodium hydrogen carbonate in methylene chloride using the microwave irradiation technique

Status of glucose metabolism including insulin resistance and beta cell function in overtly iron loaded Thalassemia patients

BACKGROUND Abnormality of glucose metabolism is a frequent complication in Thalassemia patients. Both insulin deficiency and insulin resistance has been proposed in its pathogenesis. Some form of abnormality in glucose metabolism is expected at an earlier age in these patients in developing countries like India and Nepal where iron overload is excessive due to lack of chelation therapy. MATERIALS AND METHODS Fasting serum glucose and fasting serum insulin (FSI) were measured in 40 beta-thalassemia major patients, 40 Ebeta- thalassemia patients and 40 controls, all aged between 5 and 12 years. 2 hours after an appropriate dose of oral glucose feed (Children ingested 1.75 g/kg body weight maximum 75 gram dissolved in 250 to 300 ml water) blood samples were drawn again to measure post prandial serum glucose. Iron overload was assessed by measuring liver size, spleen size, total amount of packed cells transfused and serum ferritin. Insulin resistance (IR), insulin sensitivity (%S) and beta cell functions (%B) were derived from the measured laboratory parameters using the latest version of Homeostatic Model Assessment (HOMA) calculator software. RESULTS No one had impaired glucose metabolism or diabetes mellitus beta-thalassemia major patients showed evidence of insulin resistance in the form of significantly higher fasting serum insulin (p value 0.002), IR (p value 0.003), %B (p value 0.017) and significantly lower %S (0.002) when compared with controls. FSI showed positive correlation with total amount of packed cells received (r=0.372, p=0.018), serum ferritin (r=0.345, p=0.029) and spleen size (r=0.427, p=0.006). Similarly, IR also showed positive correlation with total amount of packed cells received (r=0.388, p=0.013), serum ferritin (r=0.336, p=0.034) and spleen size (r=0.425, p=0.005). %S showed negative correlation with all these parameters. %B didn&rsquo;t show any statistically significant correlation with these parameters.Ebeta- thalassemia patients didn&rsquo;t have any statistically significant difference in FSI, IR, %S and %B than controls. CONCLUSION Insulin resistance develops as the earliest abnormality in glucose metabolism in overtly iron loaded beta thalassemia major patients at an early age. Ebeta- thalassemia patients with milder phenotype do not develop dysfunction of glucose metabolism at such an early age.DOI: http://dx.doi.org/10.3126/jcmsn.v10i3.12774 Journal of College of Medical Sciences-Nepal, 2014, Vol-10, No-3, 29-36</p

1,3-Dipolar cycloadditions: Part VII¹-Cycloaddition of C,N-diarylnitrones to ethyl crotonate

1925-1933Cycloaddition of C, N-diarylnitrones to ethyl crotonate occurrs with high regio- and stereo-selectivity to furnish 3,4-trans-4,5-trans-22,3-diaryl-4-carbethoxy-5-methylisoxazolidine derivatives as the major cycloadducts. The 3,4-cis-4,5-trans stereoisomers are obtained as minor products

Prohibitin Facilitates Cellular Senescence by Recruiting Specific Corepressors To Inhibit E2F Target Genes

Prohibitin is a growth regulatory gene that has pleiotropic functions in the nucleus, mitochondria, and cytoplasmic compartments. Earlier studies had proposed a role for prohibitin in modulating cellular senescence, but the underlying mechanisms remain unknown. Here we show that senescence induced by DNA-damaging agents causes the localization of prohibitin to specific heterochromatic foci. Prohibitin could bind to heterochromatin protein 1 (HP1) family proteins and colocalized with HP1γ in senescence-associated heterochromatic foci. Further, HP1γ could synergize with prohibitin to repress E2F1-mediated transcriptional activity. The depletion of prohibitin by small interfering RNA or antisense techniques led to a reduction in the senescent phenotype, correlating with a reduced expression of senescence-associated β-galactosidase and fewer numbers of senescence-associated heterochromatic foci. Chromatin immunoprecipitation assays showed that prohibitin is needed for the recruitment of HP1γ to E2F1-regulated proliferative promoters, leading to their repression. The ablation of prohibitin prevented the recruitment of HPIγ, but not Suv39H, to the promoters upon senescence. Prohibitin-mediated recruitment of HP1γ occurred in only senescent cells, not in quiescent cells; thus, there is a dichotomy in the recruitment of different corepressors by prohibitin, depending on the type of growth arrest. These studies show that prohibitin plays a vital role in inducing cellular senescence

Nicotine induces cell proliferation by β-arrestin–mediated activation of Src and Rb–Raf-1 pathways

Recent studies have shown that nicotine, a component of cigarette smoke, can stimulate the proliferation of non-neuronal cells. While nicotine is not carcinogenic by itself, it has been shown to induce cell proliferation and angiogenesis. Here we find that mitogenic effects of nicotine in non–small cell lung cancers (NSCLCs) are analogous to those of growth factors and involve activation of Src, induction of Rb–Raf-1 interaction, and phosphorylation of Rb. Analysis of human NSCLC tumors show enhanced levels of Rb–Raf-1 complexes compared with adjacent normal tissue. The mitogenic effects of nicotine were mediated via the α(7)-nAChR subunit and resulted in enhanced recruitment of E2F1 and Raf-1 on proliferative promoters in NSCLC cell lines and human lung tumors. Nicotine stimulation of NSCLC cells caused dissociation of Rb from these promoters. Proliferative signaling via nicotinic acetylcholine receptors (nAChRs) required the scaffolding protein β-arrestin; ablation of β-arrestin or disruption of the Rb–Raf-1 interaction blocked nicotine-induced proliferation of NSCLCs. Additionally, suppression of β-arrestin also blocked activation of Src, suppressed levels of phosphorylated ERK, and abrogated Rb–Raf-1 binding in response to nicotine. It appears that nicotine induces cell proliferation by β-arrestin–mediated activation of the Src and Rb–Raf-1 pathways

Trichodermin Induces G0/G1 Cell Cycle Arrest by Inhibiting c-Myc in Ovarian Cancer Cells and Tumor Xenograft-Bearing Mice

Ovarian cancer is a fatal gynecological cancer because of a lack of early diagnosis, which often relapses as chemoresistant. Trichodermin, a trichothecene first isolated from Trichoderma viride, is an inhibitor of eukaryotic protein synthesis. However, whether trichodermin is able to suppress ovarian cancer or not was unclear. In this study, trichodermin (0.5 µM or greater) significantly decreased the proliferation of two ovarian cancer cell lines A2780/CP70 and OVCAR-3. Normal ovarian IOSE 346 cells were much less susceptible to trichodermin than the cancer cell lines. Trichodermin predominantly inhibited ovarian cancer cells by inducing G0/G1 cell cycle arrest rather than apoptosis. Trichodermin decreased the expression of cyclin D1, CDK4, CDK2, retinoblastoma protein, Cdc25A, and c-Myc but showed little effect on the expression of p21Waf1/Cip1, p27Kip1, or p16Ink4a. c-Myc was a key target of trichodermin. Trichodermin regulated the expression of Cdc25A and its downstream proteins via c-Myc. Overexpression of c-Myc attenuated trichodermin’s anti-ovarian cancer activity. In addition, trichodermin decelerated tumor growth in BALB/c nude mice, proving its effectiveness in vivo. These findings suggested that trichodermin has the potential to contribute to the treatment of ovarian cancer

Disruption of the Rb-Raf-1 Interaction Inhibits Tumor Growth and Angiogenesis

The retinoblastoma tumor suppressor protein (Rb) plays a vital role in regulating mammalian cell cycle progression and inactivation of Rb is necessary for entry into S phase. Rb is inactivated by phosphorylation upon growth factor stimulation of quiescent cells, facilitating the transition from G(1) phase to S phase. Although the signaling events after growth factor stimulation have been well characterized, it is not yet clear how these signals contact the cell cycle machinery. We had found previously that growth factor stimulation of quiescent cells lead to the direct binding of Raf-1 kinase to Rb, leading to its inactivation. Here we show that the Rb-Raf-1 interaction occurs prior to the activation of cyclin and/or cyclin-dependent kinases and facilitates normal cell cycle progression. Raf-1-mediated inactivation of Rb is independent of the mitogen-activated protein kinase cascade, as well as cyclin-dependent kinases. Binding of Raf-1 seemed to correlate with the dissociation of the chromatin remodeling protein Brg1 from Rb. Disruption of the Rb-Raf-1 interaction by a nine-amino-acid peptide inhibits Rb phosphorylation, cell proliferation, and vascular endothelial growth factor-mediated capillary tubule formation. Delivery of this peptide by a carrier molecule led to a 79% reduction in tumor volume and a 57% reduction in microvessel formation in nude mice. It appears that Raf-1 links mitogenic signaling to Rb and that disruption of this interaction could aid in controlling proliferative disorders