Novel 1,3,4-oxadiazole Targets STAT3 Signaling to Induce Antitumor Effect in Lung Cancer

Discovery of 2-Pyrazolines That Inhibit the Phosphorylation of STAT3 as Nanomolar Cytotoxic Agents

STAT3 has emerged as a validated target in cancer, being functionally associated with breast cancer (BC) development, growth, resistance to chemotherapy, metastasis, and evasion of immune surveillance. Previously, a series of compounds consisting of imidazo[1,2-a]pyridine tethered 2-pyrazolines (referred to as ITPs) were developed that inhibit STAT3 phosphorylation in estrogen receptor-positive (ER+) BC cells. Herein, a new library of derivatives consisting of imidazo[1,2-a]pyridine clubbed 2-pyrazolines 2(a-o) and its amide derivatives 3(a-af) have been synthesized. Among these derivatives, 3n and 3p displayed efficacy to reduce ER+ BC cell viability, with IC50 values of 55 and 15 nM, respectively. Molecular docking simulations predicted that compound 3p bound to STAT3 protein, with a binding energy of -9.56 kcal/mol. Using Western blot analysis, it was demonstrated that treatment of ER+ BC cells with compound 3p decreased the levels of phosphorylated STAT3 at the Tyr705 residue. In conclusion, this investigation presents the synthesis of imidazopyridine clubbed 2-pyrazolines that exhibit significant efficacy in reducing viability of ER+ BC cells. In silico docking and Western blot analyses together support compound 3p as a promising novel inhibitor of STAT3 phosphorylation, suggesting its potential as a valuable candidate for further therapeutic development.

Discovery of oxazine-linked pyrimidine as an inhibitor of breast cancer growth and metastasis by abrogating NF-κB activation

Introduction

Nuclear factor kappa (NF-κB) plays a key role in cancer cell proliferation; thus, small molecule inhibitors of NF-κB activity can effectively inhibit breast cancer (BC) progression. We have previously reported oxazine and piperazine-linked pyrimidines as novel anti-cancer agents that can suppress NF-κB activation in BC cells. Moreover, the TRX-01 compound, an oxazine-linked pyrimidine, inhibited MCF-7 cells at a concentration of 9.17 µM in the Alamar Blue assay.

Methods

This work involved the analysis of frontier molecular orbitals, HOMO-LUMO interactions, and molecular electrostatic potential for the TRX-01 structure. Additionally, the TRX-01 compound was studied for cytotoxicity, and migration as well as invasion assays were performed on BC cells.

Results

Finally, TRX-01 blocked the translocation of NF-κB from the cytoplasm to the nucleus in MCF-7 cells and reduced NF-κB and IκBα levels in a dose-dependent manner. It also suppressed migratory and invasive properties of BC cells.

Conclusion

Overall, the data indicates that TRX-01 can function as a novel blocker of BC growth and metastasis by targeting NF-κB activation.

Substrate-based synthetic strategies and biological activities of 1,3,4-oxadiazole: A review

The five-membered 1,3,4-oxadiazole heterocyclic ring has received considerable attention because of its unique bio-isosteric properties and an unusually wide spectrum of biological activities. After a century since 1,3,4-oxadiazole was discovered, its uncommon potential attracted medicinal chemist's attention, leading to the discovery of a few presently accessible drugs containing 1,3,4-oxadiazole units, and a large number of patents have been granted on research related to 1,3,4-oxadiazole. It is worth noting that interest in 1,3,4-oxadiazoles' biological applications has doubled in the last few years. Herein, this review presents a comprehensive overview of the recent achievements in the synthesis of 1,3,4-oxadiazole-based compounds and highlights the major advances in their biological applications in the last 10 years, as well as brief remarks on prospects for further development. We hope that researchers across the scientific streams will benefit from the presented review articles for designing their work related to 1,3,4-oxadiazoles.

1,3,4-Oxadiazoles as Anticancer Agents: A Review

Among the deadliest diseases, cancer is characterized by tumors or an increased number of a specific type of cell because of uncontrolled divisions during mitosis. Researchers in the current era concentrated on the development of highly selective anticancer medications due to the substantial toxicities of conventional cytotoxic drugs. Several marketed drug molecules have provided resistance against cancer through interaction with certain targets/growth factors/enzymes, such as Telomerase, Histone Deacetylase (HDAC), Methionine Aminopeptidase (MetAP II), Thymidylate Synthase (TS), Glycogen Synthase Kinase-3 (GSK), Epidermal Growth Factor (EGF), Vascular Endothelial Growth Factor (VEGF), Focal Adhesion Kinase (FAK), STAT3, Thymidine phosphorylase, and Alkaline phosphatase. The molecular structure of these drug molecules contains various heterocyclic moieties that act as pharmacophores. Recently, 1,3,4- oxadiazole (five-membered heterocyclic moiety) and its derivatives attracted researchers as these have been reported with a wide range of pharmacological activities, including anti-cancer. 1,3,4- oxadiazoles have exhibited anti-cancer potential via acting on any of the above targets. The presented study highlights the synthesis of anti-cancer 1,3,4-oxadiazoles, their mechanism of interactions with targets, along with structure-activity relationship concerning anti-cancer potential.

Discovery of imidazopyridine-pyrazoline-hybrid structure as SHP-1 agonist that suppresses phospho-STAT3 signaling in human breast cancer cells

Signal transducer and activator of transcription 3 (STAT3) promotes breast cancer malignancy and controls key processes including proliferation, differentiation, and survival in breast cancer cells. Although many methods for treating breast cancer have been improved, there is still a need to discover and develop new methods for breast cancer treatment. Therefore, we synthesized a new compound 2-(4-(2,3-dichlorophenyl)piperazin-1-yl)-1-(3-(2,6-dimethylimidazo[1,2-a]pyridin-3-yl)-5-(3-nitrophenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone (DIP). We aimed to evaluate the anti-cancer effect of DIP in breast cancer cells and clarify its mode of action. We noted that DIP abrogated STAT3 activation and STAT3 upstream kinases janus-activated kinase (JAK) and Src kinases. In addition, DIP promoted the levels of SHP-1 protein and acts as SHP-1 agonist. Further, silencing of SHP-1 gene reversed the DIP-induced attenuation of STAT3 activation and apoptosis. DIP also induced apoptosis through modulating PARP cleavage and oncogenic proteins. Moreover, DIP also significantly enhanced the apoptotic effects of docetaxel through the suppression of STAT3 activation in breast cancer cells. Overall, our data indicated that DIP may act as a suppressor of STAT3 cascade, and it could be a new therapeutic strategy in breast cancer cells.

Genistein: a promising modulator of apoptosis and survival signaling in cancer

Genistein, a commonly occurring isoflavone, has recently gained popularity owing to its ever-expanding spectrum of pharmacological benefits. In addition to health benefits such as improved bone health and reduced postmenopausal complications owing to its phytoestrogen properties, it has been widely evaluated for its anti-cancer potential. Several studies have established the potential for its usage in the management of breast, lung, and prostate cancers, and its usage has significantly evolved from early applications in traditional systems of medicine. This review offers an insight into its current status of usage, the chemistry, and pharmacokinetics of the molecule, an exploration of its apoptotic mechanisms in cancer management, and opportunities for synergism to improve therapeutic outcomes. In addition to this, the authors have presented an overview of recent clinical trials, to offer an understanding of contemporary studies and explore prospects for a greater number of focused trials, moving forward. Advancements in the application of nanotechnology as a strategy to improve safety and efficacy have also been highlighted, with a brief discussion of results from safety and toxicology studies.

Steroidal alkaloid solanidine impedes hypoxia-driven ATM phosphorylation to switch on anti-angiogenesis in lung adenocarcinoma

PURPOSE

The declined oxygen tension in the cancer cell leads to the hypoxic adaptive response and favors establishment of tumor micro environment [TEM]. The complex TME consists of interwoven hypoxic HIF-1α and DNA damage repair ATM signaling. The ATM/HIF-1α phosphorylation switch on angiogenesis and abort apoptosis. Targeting this signaling nexus would be a novel therapeutic strategy for the treatment of cancer.

BACKGROUND

Steroidal alkaloid solanidine is known for varied pharmacological role but with less molecular evidences. Our earlier findings on solanidine proven its anti-neoplastic activity by inducing apoptosis in lung cancer. In continued research, efforts have been made to establish the underlying molecular signaling in induction of DNA damage in prevailing hypoxic TME.

METHODS

The solanidine induced DNA damage was assessed trough alkali COMET assay; signaling nexus and gene expression profile analysis through IB, qRT-PCR, Gelatin Zymography, IHC, IF and ELISA. Pathophysiological modulations assessed through tube formation, migration, invasion assays. Anti-angiogenic studies through CAM, rat aorta, matrigel assays and corneal neovascularization assay. Anti-tumor activity through in-vivo DLA ascites tumor model and LLC model.

RESULTS

The results postulates, inhibition of hypoxia driven DDR proteins pATMser1981/pHIF-1αser696 by solanidine induces anti-angiogenesis. Systematic study of both non-tumorigenic and tumorigenic models in-vitro as well as in-vivo experimental system revealed the angio-regression mediated anticancer effect in lung cancer. These effects are due to the impeded expression of angiogenic mediators such as VEGF, MMP2&9 and inflammatory cytokines IL6 and TNFα to induce pathophysiological changes CONCLUSION: The study establishes new role of solanidine by targeting ATM/HIF-1α signaling to induce anti-angiogenesis for the first time. The study highlights the potentiality of plant based phytomedicine solanidine which can targets the multiple hallmarks of cancer by targeting interwoven signaling crosstalk. Such an approach through solanidine necessary to counteract heterogeneous complexity of cancer which could be nearly translated into drug.

Noncoding RNAs as regulators of STAT3 pathway in gastrointestinal cancers: Roles in cancer progression and therapeutic response

Gastrointestinal (GI) tumors (cancers of the esophagus, gastric, liver, pancreas, colon, and rectum) contribute to a large number of deaths worldwide. STAT3 is an oncogenic transcription factor that promotes the transcription of genes associated with proliferation, antiapoptosis, survival, and metastasis. STAT3 is overactivated in many human malignancies including GI tumors which accelerates tumor progression, metastasis, and drug resistance. Research in recent years demonstrated that noncoding RNAs (ncRNAs) play a major role in the regulation of many signaling pathways including the STAT3 pathway. The major types of endogenous ncRNAs that are being extensively studied in oncology are microRNAs, long noncoding RNAs, and circular RNAs. These ncRNAs can either be tumor-promoters or tumor-suppressors and each one of them imparts their activity via different mechanisms. The STAT3 pathway is also tightly modulated by ncRNAs. In this article, we have elaborated on the tumor-promoting role of STAT3 signaling in GI tumors. Subsequently, we have comprehensively discussed the oncogenic as well as tumor suppressor functions and mechanism of action of ncRNAs that are known to modulate STAT3 signaling in GI cancers.

Discovery of Pyrimidine- and Coumarin-Linked Hybrid Molecules as Inducers of JNK Phosphorylation through ROS Generation in Breast Cancer Cells

Human epidermal growth factor receptor 2 (HER2)-positive breast cancer exhibits early relapses, poor prognoses, and high recurrence rates. Herein, a JNK-targeting compound has been developed that may be of utility in HER2-positive mammary carcinoma. The design of a pyrimidine-and coumarin-linked structure targeting JNK was explored and the lead structure PC-12 [4-(3-((2-((4-chlorobenzyl)thio) pyrimidin-4-yl)oxy)propoxy)-6-fluoro-2H-chromen-2-one (5d)] was observed to selectively inhibit the proliferation of HER2-positive BC cells. The compound PC-12 exerted DNA damage and induced apoptosis in HER-2 positive BC cells more significantly compared to HER-2 negative BC cells. PC-12 induced PARP cleavage and down-regulated the expression of IAP-1, BCL-2, SURVIVIN, and CYCLIN D1 in BC cells. In silico and theoretical calculations showed that PC-12 could interact with JNK, and in vitro studies demonstrated that it enhanced JNK phosphorylation through ROS generation. Overall, these findings will assist the discovery of new compounds targeting JNK for use in HER2-positive BC cells.

Design and Activity of Novel Oxadiazole Based Compounds That Target Poly(ADP-ribose) Polymerase

Novel PARP inhibitors with selective mode-of-action have been approved for clinical use. Herein, oxadiazole based ligands that are predicted to target PARP-1 have been synthesized and screened for the loss of cell viability in mammary carcinoma cells, wherein seven compounds were observed to possess significant IC₅₀ values in the range of 1.4 to 25 µM. Furthermore, compound 5u, inhibited the viability of MCF-7 cells with an IC₅₀ value of 1.4µM, when compared to Olaparib (IC₅₀ = 3.2 µM). Compound 5s also decreased cell viability in MCF-7 and MDA-MB-231 cells with IC₅₀ values of 15.3 and 19.2 µM, respectively. Treatment of MCF-7 cells with compounds 5u and 5s produced PARP cleavage, H2AX phosphorylation and CASPASE-3 activation comparable to that observed with Olaparib. Compounds 5u and 5s also decreased foci-formation and 3D Matrigel growth of MCF-7 cells equivalent to or greater than that observed with Olaparib. Finally, in silico analysis demonstrated binding of compound 5s towardsthe catalytic site of PARP-1, indicating that these novel oxadiazoles synthesized herein may serve as exemplars for the development of new therapeutics in cancer.

Antiproliferative pharmacophore azo-hydrazone analogue BT-1F exerts death signalling pathway targeting STAT3 in solid tumour

BACKGROUND

Anomalous activation of intra-cellular signalling cascades confers neoplastic properties on malignant cells. The JAK2/STAT3 proteins play a pivotal role in the pathogenesis of most of the solid malignancies. The over expression of STAT3 in these tumours results in an evasion of apoptosis and thereby pathogenesis. Hence, strategy to target STAT3 to regress tumour development is an emerging new concept. As an approach, anti-neoplastic drug, Azo-hydrozone analogue, BT-1F with potential anti-proliferative effect was evaluated to demonstrate its capacity to counteract STAT3 signal with mechanistic approach.

METHODS

Cell based screening for cytotoxicity was performed through MTT, LDH and Trypan blue. The BT-1F induced anti-clonogenic property by clonogenic assay. The apoptotic capacity was examined by crystal violet staining, flow cytometry, Annexin-FITC, DAPI and TUNEL assay. The altered signalling events were studied using immunoblot. The drug-induced anti-tumour effect was evaluated in an in-vivo solid tumour model and molecular interaction was further validated by in-silico studies.

RESULTS

The BT-1F exerts chemo-sensitivity specifically against EAC and A549 cells without altering its normal counterpart. The anti-proliferative/anti-clonogenic effect was due to the induction of apoptosis through inhibition of STAT3^Tyr705 signal. Eventually downstream signalling proteins p53, Bax, Bad and Bcl-xL were significantly altered. Further in-vivo experimental results validated  in-vitro findings. The computational approaches assures the BT-1F efficiency in binding with STAT3.

CONCLUSION

Systemic validation of STAT3 target drug, BT-1F in in-vitro, in-silico and in-vivo models has promising strategy for solid cancer treatment.

Anti-neoplastic pharmacophore benzophenone-1 coumarin (BP-1C) targets JAK2 to induce apoptosis in lung cancer

Reigning of the abnormal gene activation associated with survival signalling in lung cancer leads to the anomalous growth and therapeutic failure. Targeting specific cell survival signalling like JAK2/STAT3 nexus has become a major focus of investigation to establish a target specific treatment. The 2-bromobenzoyl-4-methylphenoxy-acetyl hydra acetyl Coumarin (BP-1C), is new anti-neoplastic agent with apoptosis inducing capacity. The current study was aimed to develop antitumor phramacophore, BP-1C as JAK2 specific inhibitor against lung neoplastic progression. The study validates and identifies the molecular targets of BP-1C induced cell death. Cell based screening against multiple cancer cell lines identified, lung adenocarcinoma as its specific target through promotion of apoptosis. The BP-1C is able to induce, specific hall marks of apoptosis and there by conferring anti-neoplastic activity. Validation of its molecular mechanism, identified, BP-1C specifically targets JAK2^Tyr1007/1008 phosphorylation, and inhibits its downstream STAT3^Tyr705 signalling pathway to induce cell death. As a consequence, modulation in Akt/Src survival signal and altered expression of interwoven apoptotic genes were evident. The results were reproducible in an in-vivo LLC tumor model and in-ovo xenograft studies. The computational approaches viz, drug finger printing confers, BP-1C as novel class JAK2 inhibitor and molecular simulations studies assures its efficiency in binding with JAK2. Overall, BP-1C is a novel JAK2 inhibitor with experimental evidence and could be effectively developed into a promising drug for lung cancer treatment.

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 STAT3^Y705. 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.

Paradoxical functions of long noncoding RNAs in modulating STAT3 signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal and leading types of cancer threatening the globe with a high mortality rate. STAT3 is an oncogenic transcription factor that is aberrantly activated in several human malignancies including HCC. Many STAT3-driven genes control cell proliferation and survival, apoptotic resistance, cell cycle progression, metastasis, and chemotherapeutic resistance. STAT3 signaling is regulated by endogenous modulators such as protein tyrosine phosphatase (PTP), suppressor of cytokine signaling (SOCS), protein inhibitor of activated STAT (PIAS), and various long noncoding RNAs (lncRNAs). Interestingly, lncRNAs have been reported to exhibit oncogenic and tumor suppressor functions, and these effects are mediated through diverse molecular mechanisms including sponging of microRNAs (miRs), transcription activation/inhibition, and epigenetic modifications. In this article, we have discussed the possible role of STAT3 signaling in hepatocarcinogenesis and various mechanisms by which lncRNAs impart their oncogenic or tumor suppressive action by modulating the STAT3 pathway in HCC.

Synthesis and Anticancer Evaluation of New 1,3,4-Oxadiazole Derivatives

In order to develop novel chemotherapeutic agents with potent anticancer activities, a series of new 2,5-diaryl/heteroaryl-1,3,4-oxadiazoles were designed and synthesized. The structures of the new compounds were established using elemental analyses, IR and NMR spectral data. The compounds were evaluated for their anticancer potential on two standardized human cell lines, HT-29 (colon adenocarcinoma) and MDA-MB-231 (breast adenocarcinoma). Cytotoxicity was measured by MTS assay, while cell cycle arrest and apoptosis assays were conducted using a flow cytometer, the results showing that the cell line MDA-MB-231 is more sensitive to the compounds' action. The results of the predictive studies using the PASS application and the structural similarity analysis indicated STAT3 and miR-21 as the most probable pharmacological targets for the new compounds. The promising effect of compound 3e, 2-[2-(phenylsulfanylmethyl)phenyl]-5-(4-pyridyl)-1,3,4-oxadiazole, especially on the MDA-MB-231 cell line motivates future studies to improve the anticancer profile and to reduce the toxicological risks. It is worth noting that 3e produced a low toxic effect in the D. magna 24 h assay and the predictive studies on rat acute toxicity suggest a low degree of toxic risks.