The strict regulation of HIF-1α by non-coding RNAs: new insight towards proliferation, metastasis, and therapeutic resistance strategies.

The hypoxic environment is prominently witnessed in most solid tumors and is associated with the promotion of cell proliferation, epithelial-mesenchymal transition (EMT), angiogenesis, metabolic reprogramming, therapeutic resistance, and metastasis of tumor cells. All the effects are mediated by the expression of a transcription factor hypoxia-inducible factor-1α (HIF-1α). HIF-1α transcriptionally modulates the expression of genes responsible for all the aforementioned functions. The stability of HIF-1α is regulated by many proteins and non-coding RNAs (ncRNAs). In this article, we have critically discussed the crucial role of ncRNAs [such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), Piwi-interacting RNAs (piRNAs), and transfer RNA (tRNA)-derived small RNAs (tsRNAs)] in the regulation of stability and expression of HIF-1α. We have comprehensively discussed the molecular mechanisms and relationship of HIF-1α with each type of ncRNA in either promotion or repression of human cancers and therapeutic resistance. We have also elaborated on ncRNAs that are in clinical examination for the treatment of cancers. Overall, the majority of aspects concerning the relationship between HIF-1α and ncRNAs have been discussed in this article.

Cannabidiol activates MAPK pathway to induce apoptosis, paraptosis, and autophagy in colorectal cancer cells.

Mitogen-activated protein kinase (MAPK) activation by natural compounds is known to be involved in the induction of apoptosis, paraptosis, and autophagy. Cannabidiol (CBD), a bioactive compound found in Cannabis sativa, is endowed with many pharmacological activities. We investigated the cytotoxic effect of CBD in a panel of colorectal cancer (CRC) cells (HT-29, SW480, HCT-116, and HCT-15). CBD induced significant cytotoxicity as evidenced by the results of MTT  assay, live-dead assay, and flow cytometric analysis. Since CBD displayed cytotoxicity against CRC cells, we examined the effect of CBD on apoptosis, paraptosis, and autophagy. CBD decreased the expression of antiapoptotic proteins and increased the Annexin-V-positive as well as TUNEL-positive cells suggesting that CBD induces apoptosis. CBD increased the expression of ATF4 (activating transcription factor 4) and CHOP (CCAAT/enhancer-binding protein homologous protein), elevated endoplasmic reticulum stress, and enhanced reactive oxygen species levels indicating that CBD also promotes paraptosis. CBD also induced the expression of Atg7, phospho-Beclin-1, and LC3 suggesting that CBD also accelerates autophagy. Since, the MAPK pathway is a common cascade that is involved in the regulation of apoptosis, paraptosis, and autophagy, we investigated the effect of CBD on the activation of JNK, p38, and ERK pathways. CBD activated all the forms of MAPK proteins and pharmacological inhibition of these proteins reverted the observed effects. Our findings implied that CBD could induce CRC cell death by activating apoptosis, paraptosis, and autophagy through the activation of the MAPK pathway.

Hypoxia signaling in hepatocellular carcinoma: Challenges and therapeutic opportunities.

Hepatocellular carcinoma (HCC) is one of the most common cancers with a relatively high cancer-related mortality. The uncontrolled proliferation of HCC consumes a significant amount of oxygen, causing the development of a hypoxic tumor microenvironment (TME). Hypoxia-inducible factors (HIFs), crucial regulators in the TME, activate several cancer hallmarks leading to the hepatocarcinogenesis of HCC and resistance to current therapeutics. As such, HIFs and their signaling pathways have been explored as potential therapeutic targets for the future management of HCC. This review discusses the current understanding of the structure and function of HIFs and their complex relationship with the various cancer hallmarks. To address tumor hypoxia, this review provides an insight into the various potential novel therapeutic agents for managing HCC, such as hypoxia-activated prodrugs, HIF inhibitors, nanomaterials, antisense oligonucleotides, and natural compounds, that target HIFs/hypoxic signaling pathways in HCC. Because of HCC's relatively high incidence and mortality rates in the past decades, greater efforts should be put in place to explore novel therapeutic approaches to improve the outcome for HCC patients.

Natural compounds targeting nuclear receptors for effective cancer therapy.

Human nuclear receptors (NRs) are a family of forty-eight transcription factors that modulate gene expression both spatially and temporally. Numerous biochemical, physiological, and pathological processes including cell survival, proliferation, differentiation, metabolism, immune modulation, development, reproduction, and aging are extensively orchestrated by different NRs. The involvement of dysregulated NRs and NR-mediated signaling pathways in driving cancer cell hallmarks has been thoroughly investigated. Targeting NRs has been one of the major focuses of drug development strategies for cancer interventions. Interestingly, rapid progress in molecular biology and drug screening reveals that the naturally occurring compounds are promising modern oncology drugs which are free of potentially inevitable repercussions that are associated with synthetic compounds. Therefore, the purpose of this review is to draw our attention to the potential therapeutic effects of various classes of natural compounds that target NRs such as phytochemicals, dietary components, venom constituents, royal jelly-derived compounds, and microbial derivatives in the establishment of novel and safe medications for cancer treatment. This review also emphasizes molecular mechanisms and signaling pathways that are leveraged to promote the anti-cancer effects of these natural compounds. We have also critically reviewed and assessed the advantages and limitations of current preclinical and clinical studies on this subject for cancer prophylaxis. This might subsequently pave the way for new paradigms in the discovery of drugs that target specific cancer types.

Kaempferide triggers apoptosis and paraptosis in pancreatic tumor cells by modulating the ROS production, SHP-1 expression, and the STAT3 pathway.

Pancreatic cancer is one of the deadliest diseases with a poor prognosis and a five-survival rate. The STAT3 pathway is hyperactivated which contributes to the sustained proliferative signals in pancreatic cancer cells. We have isolated kaempferide (KF), an O-methylated flavonol, from the green propolis of Mimosa tenuiflora and examined its effect on two forms of cell death namely, apoptosis and paraptosis. KF significantly increased the cleavage of caspase-3 and PARP. It also downmodulated the expression of Alix (an intracellular inhibitor of paraptosis) and increased the expression of CHOP and ATF4 (transcription factors that promote paraptosis) indicating that KF promotes apoptosis as well as paraptosis. KF also increased intracellular reactive oxygen species (ROS) suggesting the perturbance of the redox state. N-acetylcysteine reverted the apoptosis- and paraptosis-inducing effects of KF. Some ROS inducers are known to suppress the STAT3 pathway and investigation revealed that KF downmodulates STAT3 and its upstream kinases (JAK1, JAK2, and Src). Additionally, KF also elevated the expression of SHP-1, a tyrosine phosphatase which is involved in the negative modulation of the STAT3 pathway. Knockdown of SHP-1 prevented KF-driven STAT3 inhibition. Altogether, KF has been identified as a promoter of apoptosis and paraptosis in pancreatic cancer cells through the elevation of ROS generation and SHP-1 expression.

Targeting STAT3 signaling pathway in cancer by agents derived from Mother Nature.

Signal transducer and activator of transcription (STAT) proteins are latent transcription factors that reside in the cytoplasm of several types of cells. In canonical signaling, upon stimulation by cytokines and growth factors, STATs get activated and translocate into the nucleus to transcribe target genes. Among STATs, the STAT3 variant has been studied extensively and implicated in diverse human malignancies. Transcriptionally, STAT3 can upregulate the expression of genes associated with cell proliferation, antiapoptosis, prosurvival, angiogenesis, metastasis, and immune evasion. STAT3 can be constitutively activated in a broad range of human cancers including solid as well as hematological tumors and overexpression of STAT3 has been observed in a wide-range of patient-derived tumor tissue samples that may contribute to dismal prognosis. In contrast, blockade of STAT3 activation using inhibitors or knockdown systems can markedly suppress tumor progression, thus highlighting the significance of abrogating STAT3 signaling cascade in cancer therapy. In this review, we have provided a comprehensive overview of mechanisms of STAT3 signal transduction and its endogenous negative modulators, the role of STAT3 in oncogenesis, the interplay of miRNAs in STAT3 signaling, and mechanisms involved in persistent activation of STAT3. Furthermore, the review also provides a detailed overview of STAT3 signaling inhibition by selected natural compounds, which have displayed potent activity in various preclinical cancer model.

Bacteria as a treasure house of secondary metabolites with anticancer potential.

Cancer stands in the frontline among leading killers worldwide and the annual mortality rate is expected to reach 16.4 million by 2040. Humans suffer from about 200 different types of cancers and many of them have a small number of approved therapeutic agents. Moreover, several types of major cancers are diagnosed at advanced stages as a result of which the existing therapies have limited efficacy against them and contribute to a dismal prognosis. Therefore, it is essential to develop novel potent anticancer agents to counteract cancer-driven lethality. Natural sources such as bacteria, plants, fungi, and marine microorganisms have been serving as an inexhaustible source of anticancer agents. Notably, over 13,000 natural compounds endowed with different pharmacological properties have been isolated from different bacterial sources. In the present article, we have discussed about the importance of natural products, with special emphasis on bacterial metabolites for cancer therapy. Subsequently, we have comprehensively discussed the various sources, mechanisms of action, toxicity issues, and off-target effects of clinically used anticancer drugs (such as actinomycin D, bleomycin, carfilzomib, doxorubicin, ixabepilone, mitomycin C, pentostatin, rapalogs, and romidepsin) that have been derived from different bacteria. Furthermore, we have also discussed some of the major secondary metabolites (antimycins, chartreusin, elsamicins, geldanamycin, monensin, plicamycin, prodigiosin, rebeccamycin, salinomycin, and salinosporamide) that are currently in the clinical trials or which have demonstrated potent anticancer activity in preclinical models. Besides, we have elaborated on the application of metagenomics in drug discovery and briefly described about anticancer agents (bryostatin 1 and ET-743) identified through the metagenomics approach.

A comprehensive review of the multifaceted role of the microbiota in human pancreatic carcinoma.

Pancreatic carcinoma is associated with one of the worst clinical outcomes throughout the globe because of its aggressive, metastatic, and drug-resistant nature. During the past decade, several studies have shown that oral, gut, and tumor microbiota play a critical role in the modulation of metabolism and immune responses. Growing pieces of evidence have proved beyond a doubt that the microbiota has a unique ability to influence the tumor microenvironment as well as the metabolism of chemotherapeutic agents or drugs. Given this, microbiota, known as the ecological community of microorganisms, stands to be an avenue of quality research. In this review, we provide detailed and critical information on the role of oral, gut, and pancreatic microbiota disruptions in the development of pancreatic carcinoma. Moreover, we comprehensively discuss the different types of microbiota, their potential role, and mechanism associated with pancreatic carcinoma. The microbiome provides the unique opportunity to enhance the effectiveness of chemotherapeutic agents and immunotherapies for pancreatic cancer by maintaining the right type of microbiota and holds a promising future to enhance the clinical outcomes of patients with pancreatic carcinoma.

Mechanism of epithelial-mesenchymal transition in cancer and its regulation by natural compounds.

Epithelial-mesenchymal transition (EMT) is a complex process with a primordial role in cellular transformation whereby an epithelial cell transforms and acquires a mesenchymal phenotype. This transformation plays a pivotal role in tumor progression and self-renewal, and exacerbates resistance to apoptosis and chemotherapy. EMT can be initiated and promoted by deregulated oncogenic signaling pathways, hypoxia, and cells in the tumor microenvironment, resulting in a loss-of-epithelial cell polarity, cell-cell adhesion, and enhanced invasive/migratory properties. Numerous transcriptional regulators, such as Snail, Slug, Twist, and ZEB1/ZEB2 induce EMT through the downregulation of epithelial markers and gain-of-expression of the mesenchymal markers. Additionally, signaling cascades such as Wnt/ß-catenin, Notch, Sonic hedgehog, nuclear factor kappa B, receptor tyrosine kinases, PI3K/AKT/mTOR, Hippo, and transforming growth factor-ß pathways regulate EMT whereas they are often deregulated in cancers leading to aberrant EMT. Furthermore, noncoding RNAs, tumor-derived exosomes, and epigenetic alterations are also involved in the modulation of EMT. Therefore, the regulation of EMT is a vital strategy to control the aggressive metastatic characteristics of tumor cells. Despite the vast amount of preclinical data on EMT in cancer progression, there is a lack of clinical translation at the therapeutic level. In this review, we have discussed thoroughly the role of the aforementioned transcription factors, noncoding RNAs (microRNAs, long noncoding RNA, circular RNA), signaling pathways, epigenetic modifications, and tumor-derived exosomes in the regulation of EMT in cancers. We have also emphasized the contribution of EMT to drug resistance and possible therapeutic interventions using plant-derived natural products, their semi-synthetic derivatives, and nano-formulations that are described as promising EMT blockers.

Brucein D imparts a growth inhibitory effect in multiple myeloma cells by abrogating the Akt-driven signaling pathway.

The Akt signaling pathway is an oncogenic cascade activated in the bone marrow microenvironment of multiple myeloma (MM) cells and contributes to their uncontrolled proliferation. Abrogation of Akt signaling has been presented as one of the prime therapeutic targets in the treatment of MM. In the present report, we have investigated the effect of Brucein D (BD) on Akt-driven signaling events in MM cells. BD (300 nM) substantially inhibited cell viability and imparted growth-inhibitory effects in U266 cells as evidenced by cell viability assays and flow cytometric analysis. Effect of BD on cell viability was evaluated by MTT assay. Apoptotic cells and cell cycle arrest by BD were analyzed by flow cytometer. The results of the TUNEL assay and western blotting showed that BD induces apoptosis of MM cells by activating caspase-8 and 9 with subsequent reduction in the expression of antiapoptotic proteins (Bcl-2, Bcl-xl, survivin, cyclin D1, COX-2, VEGF, MMP-9). Analysis of activated kinases by Phospho-Kinase Array Kit revealed that Akt, p70S6K, HSP60, p53, and WNK1 were strongly expressed in untreated cells and BD treatment reversed this effect. Using transfection experiments, AKT depletion led to a decrease in phosphorylation of Akt, mTOR, p70S6K, and WNK. However, Akt overexpression led to increase in phosphorylation of these proteins. Depletion of Akt potentiated the apoptosis-inducing effect of BD whereas overexpression displayed resistance to BD-induced apoptosis suggesting the role of Akt in chemoresistance. Taken together, BD mitigates Akt-dependent signaling pathways in MM cells to impart its anticancer activity.

CXCR4 expression is elevated in TNBC patient derived samples and Z-guggulsterone abrogates tumor progression by targeting CXCL12/CXCR4 signaling axis in preclinical breast cancer model.

Environmental factors such as exposure to ionizing radiations, certain environmental pollutants, and toxic chemicals are considered as risk factors in the development of breast cancer. Triple-negative breast cancer (TNBC) is a molecular variant of breast cancer that lacks therapeutic targets such as progesterone receptor, estrogen receptor, and human epidermal growth factor receptor-2 which makes the targeted therapy ineffective in TNBC patients. Therefore, identification of new therapeutic targets for the treatment of TNBC and the discovery of new therapeutic agents is the need of the hour. In this study, CXCR4 was found to be highly expressed in majority of breast cancer tissues and metastatic lymph nodes derived from TNBC patients. CXCR4 expression is positively correlated with breast cancer metastasis and poor prognosis of TNBC patients suggesting that suppression of CXCR4 expression could be a good strategy in the treatment of TNBC patients. Therefore, the effect of Z-guggulsterone (ZGA) on the expression of CXCR4 in TNBC cells was examined. ZGA downregulated protein and mRNA expression of CXCR4 in TNBC cells and proteasome inhibition or lysosomal stabilization had no effect on the ZGA-induced CXCR4 reduction. CXCR4 is under the transcriptional control of NF-κB, whereas ZGA was found to downregulate transcriptional activity of NF-κB. Functionally, ZGA downmodulated the CXCL12-driven migration/invasion in TNBC cells. Additionally, the effect of ZGA on growth of tumor was investigated in the orthotopic TNBC mice model. ZGA presented good inhibition of tumor growth and liver/lung metastasis in this model. Western blotting and immunohistochemical analysis indicated a reduction of CXCR4, NF-κB, and Ki67 in tumor tissues. Computational analysis suggested PXR agonism and FXR antagonism as targets of ZGA. In conclusion, CXCR4 was found to be overexpressed in majority of patient-derived TNBC tissues and ZGA abrogated the growth of TNBC tumors by partly targeting the CXCL12/CXCR4 signaling axis.

The multifaceted antineoplastic role of pyrimethamine against human malignancies.

Cancer accounted for nearly 10 million deaths in 2020 and is the second leading cause of death worldwide. The chemotherapeutic agents that are in clinical practice possess a broad range of severe adverse effects towards vital organs which emphasizes the importance of the discovery of new therapeutic agents or repurposing of existing drugs for the treatment of human cancers. Pyrimethamine is an antiparasitic drug used for the treatment of malaria and toxoplasmosis with a well-documented excellent safety profile. In the last 5 years, numerous efforts have been made to explore the anticancer potential of pyrimethamine in in vitro and in vivo preclinical models and to repurpose it as an anticancer agent. The studies have demonstrated that pyrimethamine inhibits oncogenic proteins such as STAT3, NF-κB, DX2, MAPK, DHFR, thymidine phosphorylase, telomerase, and many more in a different types of cancer models. Moreover, pyrimethamine has been reported to work in synergy with other anticancer agents, such as temozolomide, to induce apoptosis of tumor cells. Recently, the results of phase-1/2 clinical trials demonstrated that pyrimethamine administration reduces the expression of STAT3 signature genes in tumor tissues of chronic lymphocytic leukemia patients with a good therapeutic response. In the present article, we have reviewed most of the published articles related to the antitumor effects of pyrimethamine in malignancies of breast, liver, lung, skin, ovary, prostate, pituitary, and leukemia in in vitro and in vivo settings. We have also discussed the pharmacokinetic profile and results of clinical trials obtained after pyrimethamine treatment. From these studies, we believe that pyrimethamine has the potential to be repurposed as an anticancer drug.

Leelamine Exerts Antineoplastic Effects in Association with Modulating Mitogen­Activated Protein Kinase Signaling Cascade.

Mitogen­activated protein kinase (MAPK) pathway is a prominent signaling cascade that modulates cell proliferation, apoptosis, stress response, drug resistance, immune response, and cell motility. Activation of MAPK by various small molecules/natural compounds has been demonstrated to induce apoptosis in cancer cells. Herein, the effect of leelamine (LEE, a triterpene derived from bark of pine trees) on the activation of MAPK in hepatocellular carcinoma (HCC) and breast cancer (BC) cells was investigated. LEE induced potent cytotoxicity of HCC (HepG2 and HCCLM3) and BC (MDA-MB-231 and MCF7) cells over normal counterparts (MCF10A). LEE significantly enhanced the phosphorylation of p38 and JNK MAPKs in a dose-dependent fashion and it did not affect the phosphorylation of ERK in HCC and BC cells. The apoptosis-driving effect of LEE was further demonstrated by cleavage of procaspase-3/Bid and suppression of prosurvival proteins (Bcl-xL and XIAP). Furthermore, LEE also reduced the SDF1-induced-migration and -invasion of HCC and BC cells. Taken together, the data demonstrated that LEE promotes apoptosis and induces an anti-motility effect by activating p38 and JNK MAPKs in HCC and BC cells.

Long non-coding RNA/epithelial-mesenchymal transition axis in human cancers: Tumorigenesis, chemoresistance, and radioresistance.

Epithelial-to-mesenchymal transition (EMT) is a process that involves the transformation of polarized epithelial cells to attain a mesenchymal phenotype that presents an elevated migratory potential, invasiveness, and antiapoptotic properties. Many studies have demonstrated that EMT is a prominent event that is associated with embryogenesis, tumor progression, metastasis, and therapeutic resistance. The EMT process is driven by key transcription factors (such as Snail, Twist, ZEB, and TGF-ß) and several long non-coding RNAs (lncRNAs) in many non-pathological as well as pathological conditions. In the present report, we have comprehensively discussed the oncogenic and tumor suppressor role of lncRNAs and their mechanism of action in the regulation of the EMT process in various cancers such as brain tumors, gastrointestinal tumors, and gynecological and urological tumors. We have also elaborated on the role of lncRNAs in the regulation of EMT-related transcription factors (such as Snail, Twist, ZEB, and TGF-ß) and therapeutic response (chemoresistance and radioresistance). Lastly, we have emphasized the role of exosomal lncRNAs in the regulation of EMT, metastasis, and therapeutic response in the aforementioned cancers. Taken together, this review provides a detailed insight into the understanding of role of lncRNAs/exosomal lncRNAs in EMT, metastasis, and therapeutic response in human cancers.

Euphorbiasteroid Abrogates EGFR and Wnt/ß-Catenin Signaling in Non-Small-Cell Lung Cancer Cells to Impart Anticancer Activity.

EGFR and Wnt/ß-catenin signaling pathways play a prominent role in tumor progression in various human cancers including non-small-cell lung carcinoma (NSCLC). Transactivation and crosstalk between the EGFR and Wnt/ß-catenin pathways may contribute to the aggressiveness of cancers. Targeting these oncogenic pathways with small molecules is an attractive approach to counteract various types of cancers. In this study, we demonstrate the effect of euphorbiasteroid (EPBS) on the EGFR and Wnt/ß-catenin pathways in NSCLC cells. EPBS induced preferential cytotoxicity toward A549 (wildtype EGFR-expressing) cells over PC-9 (mutant EGFR-expressing) cells. EPBS suppressed the expression of EGFR, Wnt3a, ß-catenin, and FZD-1, and the reduction in ß-catenin levels was found to be mediated through the activation of GSK-3ß. EPBS reduced the phosphorylation of GSK-3ßS9 with a parallel increase in ß-TrCP and phosphorylation of GSK-3ßY216. Lithium chloride treatment increased the phosphorylation of GSK-3ßS9 and nuclear localization of ß-catenin, whereas EPBS reverted these effects. Forced expression or depletion of EGFR in NSCLC cells increased or decreased the levels of Wnt3a, ß-catenin, and FZD-1, respectively. Overall, EPBS abrogates EGFR and Wnt/ß-catenin pathways to impart its anticancer activity in NSCLC cells.

Crocetin imparts antiproliferative activity via inhibiting STAT3 signaling in hepatocellular carcinoma.

STAT3 is a key oncogenic transcription factor, often overactivated in several human cancers including hepatocellular carcinoma (HCC). STAT3 modulates the expression of genes that are connected with cell proliferation, antiapoptosis, metastasis, angiogenesis, and immune evasion in tumor cells. In this study, we investigated the effect of crocetin on the growth of HCC cells and dissected its underlying molecular mechanism in imparting a cytotoxic effect. Crocetin suppressed proliferation, promoted apoptosis, and counteracted the invasive capacity of HCC cells. Besides, crocetin downregulated the constitutive/inducible STAT3 activation (STAT3Y705 ), nuclear accumulation of STAT3 along with suppression of its DNA binding activity in HCC cells with no effect on STAT5 activation. Crocetin suppressed the activity of upstream kinases such as Src, JAK1, and JAK2. Sodium pervanadate treatment terminated the crocetin-propelled STAT3 inhibition suggesting the involvement of tyrosine phosphatases. Crocetin increased the expression of SHP-1 and siRNA-mediated SHP-1 silencing resulted in the negation of crocetin-driven STAT3 inhibition. Further investigation revealed that crocetin treatment inhibited the expression of STAT3 regulated genes (Bcl-2, Bcl-xL, cyclin D1, survivin, VEGF, COX-2, and MMP-9). Taken together, this report presents crocetin as a novel abrogator of the STAT3 pathway in HCC cell lines.

Pyrimidine-2,4-dione targets STAT3 signaling pathway to induce cytotoxicity in hepatocellular carcinoma cells.

Signal transducer and activator of transcription 3 (STAT3) is a tumorigenic transcription factor that is persistently activated in various human cancers including hepatocellular carcinoma (HCC). Therefore, STAT3 is considered as a prominent target to counteract the uncontrolled proliferation of cancer cells. In the present report, pyrimidine-2,4-diones (N-methyluracil derivatives) (MNK1-MNK14) were synthesized in an ionic liquid (BMIm PF6) medium employing a ligand-free Suzuki-Miyaura cross-coupling process. Among the 14 derivatives, compound MNK8 showed good cytotoxicity towards both the tested cell lines and did not display a toxic effect against normal hepatocytes (LO2). MNK8 significantly increased the Sub-G1 cell count in both cell lines and the cytotoxic effect of MNK8 was found to be mediated through the suppression of constitutive phosphorylation of STAT3Y705. It also decreased the DNA interaction ability of nuclear STAT3 in HCC cells. MNK8 downregulated the levels of apoptosis-related proteins (such as Bcl-2, cyclin D1, survivin) and increased cleaved caspase-3 inferring the apoptogenic effect of MNK8. It also reduced the CXCL12-triggered cell migration and invasion in in vitro assay systems. Overall, MNK8 has been demonstrated as a new inhibitor of STAT3 signaling cascade in HCC cells.

Discovery of a small-molecule inhibitor of specific serine residue BAD phosphorylation.

Human BCL-2-associated death promoter (hBAD) is an apoptosis-regulatory protein mediating survival signals to carcinoma cells upon phosphorylation of Ser99, among other residues. Herein, we screened multiple small-molecule databases queried in a Laplacian-modified naive Bayesian-based cheminformatics platform and identified a Petasis reaction product as a site-specific inhibitor for hBAD phosphorylation. Based on apoptotic efficacy against mammary carcinoma cells, N-cyclopentyl-3-((4-(2,3-dichlorophenyl) piperazin-1-yl) (2-hydroxyphenyl) methyl) benzamide (NPB) was identified as a potential lead compound. In vitro biochemical analyses demonstrated that NPB inhibited the phosphorylation of hBAD specifically on Ser99. NPB was observed to exert this effect independently of AKT and other kinase activities despite the demonstration of AKT-mediated BAD-Ser99 phosphorylation. Using a structure-based bioinformatics platform, we observed that NPB exhibited predicted interactions with hBAD in silico and verified the same by direct binding kinetics. NPB reduced phosphorylation of BAD-Ser99 and enhanced caspase 3/7 activity with associated loss of cell viability in various human cancer cell lines derived from mammary, endometrial, ovarian, hepatocellular, colon, prostatic, and pancreatic carcinoma. Furthermore, by use of a xenograft model, it was observed that NPB, as a single agent, markedly diminished BAD phosphorylation in tumor tissue and significantly inhibited tumor growth. Similar doses of NPB utilized in acute toxicity studies in mice did not exhibit significant effects. Hence, we report a site-specific inhibitor of BAD phosphorylation with efficacy in tumor models.

Synthesis of CC, CN coupled novel substituted dibutyl benzothiazepinone derivatives and evaluation of their thrombin inhibitory activity.

The formation of a thrombus is a key event in thromboembolic disorders, that contribute to high mortality and morbidity in affected patients. In the present study, we synthesized a library of novel substituted 3,3-dibutyl-8-methoxy-2,3-dihydrobenzo [b] [1,4] thiazepin-4(5H)-one derivatives which were tested for their platelet aggregation and thrombin inhibitory activity. Among the tested compounds, 3,3-dibutyl-7-(2-chlorophenyl)-8-methoxy-2,3-dihydrobenzo[b] [1,4]thiazepin-4(5H)-one (DCT) displayed the maximum thrombin inhibition with an IC50 value of 3.85 µM and thus DCT was chosen for further studies. Next, the effect of DCT on primary hemostasis was evaluated using agonist-induced platelet aggregation model. The lead compound inhibited the collagen- or ADP- or thrombin-induced platelet aggregation in a dose-dependent manner. Furthermore, DCT prolonged the process of clot formation when evaluating plasma re-calcification time (320 ±â€¯11 sec at 5 µg DCT), activated partial thromboplastin time (58.0 ±â€¯0.01 sec at 2 µg), and prothrombin time (14.7 ±â€¯0.01 sec at 5 µg). Molecular docking studies suggested that the benzothiazepinones evaluated here consistently display hydrogen bonding with Ser214 of thrombin, which is similar to that of the co-crystallized ligand (1-(2R)-2-amino-3-phenyl-propanoyl-N-(2,5dichlorophenyl)methylpyrrolidine-2-carboxamide). DCT displayed additional hydrogen bonding to Ser195 and π-π interactions between its methoxyphenyl groups and Trp60, thereby providing a structural rationale for the observed biological effect.

Triazole-Pyridine Dicarbonitrile Targets Phosphodiesterase 4 to Induce Cytotoxicity in Lung Carcinoma Cells.

Phosphodiesterase 4 (PDE4) is a key enzyme involved in the hydrolysis of cyclic adenosine monophosphate (cAMP) and widely expressed in several types of cancers. The inhibition of PDE4 results in an increased concentration of intracellular cAMP levels that imparts the anti-inflammatory response in the target cells. In the present report, two series of triazolo-pyridine dicarbonitriles and substituted dihydropyridine dicarbonitriles were synthesized using green protocol (TBAB in refluxed water). We next evaluated the title compounds for their cytotoxicity towards lung cancer (A549) cells and identified 7'-[4-(methylsulfonyl)phenyl]-5'-oxo-1',5'-dihydrospiro[cyclohexane-1,2'-[1,2,4]triazolo[1,5-a]pyridine]-6',8'-dicarbonitrile (5h) and 7'-(1-methyl-1H-imidazol-2-yl)-5'-oxo-1',5'-dihydrospiro[cyclohexane-1,2'-[1,2,4]triazolo[1,5-a]pyridine]-6',8'-dicarbonitrile (5j) as lead analogs with the IC50 values of 15.2 and 24.1 µm, respectively. Furthermore, all the new compounds were tested for PDE4 inhibitory activity and 5j showed relatively good inhibitory activity towards PDE4 with inhibition of 50.9 % at 10 µm. In silico analysis demonstrated the favorable interaction of the title compounds with the target enzyme. Taken together, the present study introduces a new scaffold for the development of novel PDE4 inhibitors to fight against inflammatory diseases.