Synthesis and Cytotoxic Evaluation of Novel 2-(4-(2,2,2-Trifluoroethoxy)-3-methylpyridin-2-ylthio)-1H-benzo[d]imid azole Derivatives

The present work deals with the anticancer effect of benzimidazole derivatives associated with the pyridine framework. By varying the functional group at N-terminal of the benzimidazole by different L-amino acids, several 2-(4-(2,2,2-trifluoroethoxy)-3-methylpyridin-2-ylthio)-1H-benzo[d]imid azole derivatives 9(a-j) were synthesized. Their chemical structures were confirmed by H-1 NMR, IR and mass spectroscopic techniques. The synthesized compounds were examined for their antiproliferative effects against human leukemia cell lines, K562 and CEM. The preliminary results showed most of the derivatives had moderate antitumor activity. Compound 9j containing cysteine residue exhibited good inhibition compared to other amino acid resides. In addition DNA fragmentation results suggest that 9j is more cytotoxic and able to induce apoptosis.

Prevalence and analysis of t(14;18) and t(11;14) chromosomal translocations in healthy Indian population

Hematopoietic malignancies like leukemia and lymphoma are characteristically associated with various chromosomal translocations. Follicular lymphoma (FL) and mantle cell lymphoma (MCL) are two subtypes of non-Hodgkin's lymphoma which possess t(14;18) and t(11;14) translocations, respectively. The incidence of FL and MCL is higher in the western countries as compared to India. Interestingly, the associated translocations are also found in healthy individuals in western population, which is 50-80% for t(14;18), whereas t(11;14) occurs at a very low frequency. However, there are no studies to explore thes translocations in healthy Indian population, which could explain the lower incidence of FL and MCL. We employed Southern hybridization following nested PCR to detect above translocations in healthy individuals from India. Our results suggest that this assay can detect one t(14;18) translocation event in up to 10(7) normal cells where as one t(11;14) in 10(8) normal cells. According to our results, 87 out of 253 individuals carry t(14;18) indicating 34% prevalence in the population. The presence of this translocation was also detectable at the transcript level. Although, no gender-based difference was observed, an age-dependent increase in the prevalence of translocation was found in adults. However, even after studying 210 people, we could not detect any t(11;14) translocation, indicating that it is uncommon in Indian population. These results suggest that lower incidence of FL and MCL in India could be attributed to lower prevalence of these translocations in healthy individuals.

Cellular and molecular regulation of mammalian blastocyst hatching

In mammals including humans, failure in blastocyst hatching and implantation leads to early embryonic loss and infertility. Prior to implantation, the blastocyst must hatch out of its acellular glycoprotein coat, the zona pellucida (ZP). The phenomenon of blastocyst hatching is believed to be regulated by (i) dynamic cellular components such as actin-based trophectodermal projections (TEPs), and (ii) a variety of autocrine and paracrine molecules such as growth factors, cytokines and proteases. The spatio-temporal regulation of zona lysis by blastocyst-derived cellular and molecular signaling factors is being keenly investigated. Our studies show that hamster blastocyst hatching is acelerated by growth factors such as heparin binding-epidermal growth factor and leukemia inhibitory factor and that embryo-derived, cysteine proteases including cathepsins are responsible for blastocyst hatching. Additionally, we believe that cyclooxygenase-generated prostaglandins, estradiol-17 beta mediated estrogen receptor-alpha signaling and possibly NF kappa B could be involved in peri-hatching development. Moreover, we show that TEPs are intimately involved with lysing ZP and that the TEPs potentially enrich and harbor hatching-enabling factors. These observations provide new insights into our understanding of the key cellular and molecular regulators involved in the phenomenon of mammalian blastocyst hatching, which is essential for the establishment of early pregnancy.

Synthesis and identification of a new class of (S)-2,6-diamino-4,5,6,7-tetrahydrobenzo[d]thiazole derivatives as potent antileukemic agents

Benzothiazoles are multitarget agents with broad spectrum of biological activity. Among the antitumor agents discovered in recent years, the identification of various 2-(4-aminophenyl) benzothiazoles as potent and selective antitumor drugs against different cancer cell lines has stimulated remarkable interest. Some of the benzothiazoles are known to induce cell cycle arrest, activation of caspases and interaction with DNA molecule. Based on these interesting properties of benzothiazoles and to obtain new biologically active agents, a series of novel 4,5,6,7-tetrahydrobenzo[d]thiazole derivatives 5(a-i) were synthesized and evaluated for their efficacy as antileukemic agents in human leukemia cells (K562 and Reh). The chemical structures of the synthesized compounds were confirmed by H-1 NMR, LCMS and IR analysis. The cytotoxicity of these compounds were determined using trypan blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Results showed that, these compounds mediate a significant cytotoxic response to cancer cell lines tested. We found that the compounds having electron withdrawing groups at different positions of the phenyl ring of the thiourea moiety displayed significant cytotoxic effect with IC50 value less than 60 mu M. To rationalize the role of electron withdrawing group in the induction of cytotoxicity, we have chosen molecule 5g (IC50 similar to 15 mu M) which is having chloro substitution at ortho and para positions. Flow cytometric analysis of annexin V-FITC/ propidium iodide (PI) double staining and DNA fragmentation suggest that 5g can induce apoptosis.

Differential regulation of MRN (Mre11-Rad50-Nbs1) complex subunits and telomerase activity in cancer cells

Several lines of evidence suggest that cancer progression is associated with up-regulation or reactivation of telomerase and the underlying mechanism remains an active area of research. The heterotrimeric MRN complex, consisting of Mre11, Rad50 and Nbs1, which is required for the repair of double-strand breaks, plays a key role in telomere length maintenance. In this study, we show significant differences in the levels of expression of MRN complex subunits among various cancer cells and somatic cells. Notably, siRNA-mediated depletion of any of the subunits of MRN complex led to complete ablation of other subunits of the complex. Treatment of leukemia and prostate cancer cells with etoposide lead to increased expression of MRN complex subunits, with concomitant decrease in the levels of telomerase activity, compared to breast cancer cells. These studies raise the possibility of developing anti-cancer drugs targeting MRN complex subunits to sensitize a subset of cancer cells to radio- and/or chemotherapy. (C) 2010 Elsevier Inc. All rights reserved.

Synthesis and Identification of a new class of antileukemic agents containing 2-(arylcarboxamide)-(S)-6-amino-4,5,6,7-tetrahydrobenzod]thiazole

Recently we have reported the effect of (S)-6-aryl urea/thiourea substituted-2-amino-4,5,6,7-tetrahydrobenzod]thiazole derivatives as potent anti-leukemic agents. To elucidate further the Structure Activity Relationship (SAR) studies on the anti-leukemic activity of (S)-2,6-diamino-4,5,6,7 tetrahydrobenzod]thiazole moiety, a series of 2-arlycarboxamide substituted-(S)-6-amino-4,5,6,7-tetrahydrobenzod]thiazole were designed, synthesized and evaluated for their anti-leukemic activity by trypan blue exclusion, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) assays and cell cycle analysis. Results suggest that the position, number and bulkiness of the substituent on the phenyl ring of aryl carboxamide moiety at 2nd position of 6-amino-4,5,6,7-tetrhydrobenzod]thiazole play a key role in inhibiting the proliferation of leukemia cells. Compounds with ortho substitution showed poor activity and with meta and para substitution showed good activity. (C) 2010 Elsevier Masson SAS. All rights reserved.

Synthesis and biological evaluation of novel 2-aralkyl-5-substituted-6-(4 `-fluorophenyl)-imidazo2,1-b]1,3,4]thiadiazole derivatives as potent anticancer agents

Levamisole, the imidazo2,1-b]thiazole derivative has been reported as a potential antitumor agent. In the present study, we synthesized, characterized and evaluated biological activity of its novel analogues with substitution in the aralkyl group and on imidazothiadiazole molecules with same chemical backbone but different side chains namely 2-aralkyl-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]thiadiazoles (SCR1), 2-aralkyl-5-bromo-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-thiadiaz oles (SCR2), 2-aralkyl-5-formyl-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-thiadia zoles (SCR3) and 2-aralkyl-5-thiocyanato-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-th iadiazoles (SCR4) on leukemia cells. The cytotoxic studies showed that 3a, 4a, and 4c exhibited strong cytotoxicity while others had moderate cytotoxicity. Among these we chose 4a (IC50, 8 mu M) for understanding its mechanism of cytotoxicity. FACS analysis in conjunction with mitochondrial membrane potential and DNA fragmentation studies indicated that 4a induced apoptosis without cell cycle arrest suggesting that it could be used as a potential chemotherapeutic agent. (C) 2011 Elsevier Masson SAS. All rights reserved.

How does DNA break during chromosomal translocations?

Chromosomal translocations are one of the most common types of genetic rearrangements and are molecular signatures for many types of cancers. They are considered as primary causes for cancers, especially lymphoma and leukemia. Although many translocations have been reported in the last four decades, the mechanism by which chromosomes break during a translocation remains largely unknown. In this review, we summarize recent advances made in understanding the molecular mechanism of chromosomal translocations.

Synthesis and Antileukemic Activity of Novel 4-(3-(Piperidin-4-yl) Propyl)Piperidine Derivatives

To explore the anticancer effect associated with the piperidine framework, several (substituted phenyl) {4-[3-(piperidin-4-yl)propyl]piperidin-1-yl} methanone derivatives 3(a-i) were synthesized. Variation in the functional group at N-terminal of the piperidine led to a set of compounds bearing amide moiety. Their chemical structures were confirmed by (1)H NMR, IR and mass spectra analysis. Among these, compounds 3a, 3d and 3e were endowed with antiproliferative activity. The most active compound among this series was 3a with nitro and fluoro substitution on the phenyl ring of aryl carboxamide moiety, which inhibited the growth of human leukemia cells (K562 and Reh) at low concentration. Comparison with other derivative (3h) results shown by LDH assay, cell cycle analysis and DNA fragmentation suggested that 3a is more potent to induce apoptosis.

Synthesis and Antileukemic Activity of Novel 2-(4-(2,4-dimethoxybenzoyl)phenoxy)-1-(4-(3-(piperidin-4-yl)propyl)piper idin-1-yl)ethanone Derivatives

A series of novel 2-(4-(2,4-dimethoxybenzoyl)phenoxy)-1-(4-(3-(piperidin-4-yl)propyl) piperidin-1-yl)ethanone derivatives 9(ae) and 10(ag) were synthesized and characterized by 1H NMR, IR, mass spectral, and elemental analysis. These novel compounds were evaluated for their antileukemic activity against two human leukemic cell lines (K562 and CEM) by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay. Some of the tested compounds showed good antiproliferative activity with IC50 values ranging from 1.6 to 8.0 mu m. Compound 9c, 9e, and 10f with an electron-withdrawing halogen substituent at the para position on the phenyl ring showed excellent in vitro potency against tested human leukemia cells (K562 and CEM).

IN-VITRO CYTOTOXICITY AND CELL CYCLE ANALYSIS OF TWO NOVEL BIS-1, 2, 4-TRIAZOLE DERIVATIVES: 1,4-BIS[5-(5-MERCAPTO-1,3,4-OXADIAZOL-2-yl-METHYL)-THIO-4-(p-TOLYL)-1, 2,4-TRIAZOL-3-yl]-BUTANE (MNP-14) AND 1,4-BIS[5-(CARBETHOXY-METHYL)-THIO-4-(p-ETHOXY PHENYL)-1,2,4-TRIAZOL-3-yl]-BUTANE (MNP-16)

In the present study, we have tested the cytotoxic and DNA damage activity of two novel bis-1,2,4 triazole derivatives, namely 1,4-bis[5-(5-mercapto-1,3,4-oxadiazol-2-yl-methyl)-thio4-(p-tolyl)-1,2 ,4-triazol-3-yl]-butane (MNP-14) and 1,4-bis[5-(carbethoxy-methyl)-thio-4-(p-ethoxy phenyl) -1,2,4-triazol-3-yl]-butane (MNP-16). The effect of these molecules on cellular apoptosis was also determined. The in-vitro cytotoxicity was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay as well as Trypan blue dye exclusion methods against human acute lymphoblastic leukemia (MOLT4) and lung cancer cells (A549). Our results showed that MNP-16 induced significant cytotoxicity (IC50 of 3-5 mu M) compared with MNP-14. The cytotoxicity induced by MNP-16 was time and concentration dependent. The cell cycle analysis by flow cytometry (fluorescence-activated cell sorting [FACS]) revealed that though there was a significant increase in the apoptotic population (sub-G1 phase) with an increased concentration of MNP-14 and 16, there was no cell cycle arrest. Further, the comet assay results indicated considerable DNA

Potential G-quadruplex formation at breakpoint regions of chromosomal translocations in cancer may explain their fragility

Genetic alterations like point mutations, insertions, deletions, inversions and translocations are frequently found in cancers. Chromosomal translocations are one of the most common genomic aberrations associated with nearly all types of cancers especially leukemia and lymphoma. Recent studies have shown the role of non-B DNA structures in generation of translocations. In the present study, using various bioinformatic tools, we show the propensity of formation of different types of altered DNA structures near translocation breakpoint regions. In particular, we find close association between occurrence of G-quadruplex forming motifs and fragile regions in almost 70% of genes involved in rearrangements in lymphoid cancers. However, such an analysis did not provide any evidence for the occurrence of G-quadruplexes at the close vicinity of translocation breakpoint regions in nonlymphoid cancers. Overall, this study will help in the identification of novel non-B DNA targets that may be responsible for generation of chromosomal translocations in cancer. (C) 2012 Elsevier Inc. All rights reserved.

Novel Levamisole Derivative Induces Extrinsic Pathway of Apoptosis in Cancer Cells and Inhibits Tumor Progression in Mice

Background: Levamisole, an imidazo(2,1-b) thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4'-fluorophenyl)-5-thiocyanato-imidazo2,1-b]1,3,4]thi adiazole). Materials and Methods: ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo. Results: We have determined the IC50 value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC50 5 mu M). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models. Conclusion: Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.

Chromosomal translocations among the healthy human population: implications in oncogenesis

Chromosomal translocations are characteristic features of many cancers, especially lymphoma and leukemia. However, recent reports suggest that many chromosomal translocations can be found in healthy individuals, although the significance of this observation is still not clear. In this review, we summarize recent studies on chromosomal translocations in healthy individuals carried out in different geographical areas of the world and discuss the relevance of the observation with respect to oncogenesis.

Synthesis and evaluation of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles as anti-cancer agents

A series of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles 9a-j were obtained via multistep synthesis from hydroxybenzophenones 4a-e. The cytotoxicity of compounds 9a-j was evaluated against human leukemia cell lilies (K562 and CEM). The compounds exhibited moderate to good anti-cancer activity with compounds 9b and 9i having a chloro group exhibiting the best activity (IC50 = 10 mu M). Compound 9i exhibited activity against both the cell lines and 9b only exhibited activity against CEM. Further, a lactate dehydrogenase (LDH) assay and DNA fragmentation studies of the compounds 9a-j were also performed. (C) 2013 Elsevier Masson SAS. All rights reserved.