A novel carbazole derivative, MHY407, sensitizes cancer cells to doxorubicin-, etoposide-, and radiation treatment via DNA damage

Palindromic carbazole derivatives: unveiling their antiproliferative effect via topoisomerase II catalytic inhibition and apoptosis induction

Human DNA topoisomerases are essential for crucial cellular processes, including DNA replication, transcription, chromatin condensation, and maintenance of its structure. One of the significant strategies employed in cancer treatment involves the inhibition of a specific type of topoisomerase, known as topoisomerase II (Topo II). Carbazole derivatives, recognised for their varied biological activities, have recently become a significant focus in oncological research. This study assesses the efficacy of three symmetrically substituted carbazole derivatives: 2,7-Di(2-furyl)-9H-carbazole (27a), 3,6-Di(2-furyl)-9H-carbazole (36a), and 3,6-Di(2-thienyl)-9H-carbazole (36b) - as anticancer agents. Among investigated carbazole derivatives, compound 3,6-di(2-furyl)-9H-carbazole bearing two furan moieties emerged as a novel catalytic inhibitor of Topo II. Notably, 3,6-di(2-furyl)-9H-carbazole effectively selectively inhibited the relaxation and decatenation activities of Topo IIα, with minimal effects on the IIβ isoform. These findings underscore the potential of compound 3,6-Di(2-furyl)-9H-carbazole as a promising lead candidate warranting further investigation in the realm of anticancer drug development.

H2AX: A key player in DNA damage response and a promising target for cancer therapy

Cancer is caused by a complex interaction of factors that interrupt the normal growth and division of cells. At the center of this process is the intricate relationship between DNA damage and the cellular mechanisms responsible for maintaining genomic stability. When DNA damage is not repaired, it can cause genetic mutations that contribute to the initiation and progression of cancer. On the other hand, the DNA damage response system, which involves the phosphorylation of the histone variant H2AX (γH2AX), is crucial in preserving genomic integrity by signaling and facilitating the repair of DNA double-strand breaks. This review provides an explanation of the molecular dynamics of H2AX in the context of DNA damage response. It emphasizes the crucial role of H2AX in recruiting and localizing repair machinery at sites of chromatin damage. The review explains how H2AX phosphorylation, facilitated by the master kinases ATM and ATR, acts as a signal for DNA damage, triggering downstream pathways that govern cell cycle checkpoints, apoptosis, and the cellular fate decision between repair and cell death. The phosphorylation of H2AX is a critical regulatory point, ensuring cell survival by promoting repair or steering cells towards apoptosis in cases of catastrophic genomic damage. Moreover, we explore the therapeutic potential of targeting H2AX in cancer treatment, leveraging its dual function as a biomarker of DNA integrity and a therapeutic target. By delineating the pathways that lead to H2AX phosphorylation and its roles in apoptosis and cell cycle control, we highlight the significance of H2AX as both a prognostic tool and a focal point for therapeutic intervention, offering insights into its utility in enhancing the efficacy of cancer treatments.

Novel carbazole-oxadiazoles as potential Staphylococcus aureus germicides

Staphylococcus aureus resistance poses nonnegligible threats to the livestock industry. In light of this, carbazole-oxadiazoles were designed and synthesized for treating S. aureus infection. Bioassay discovered that 3,6-dibromocarbazole derivative 13a had effective inhibitory activities to several Gram-positive bacteria, in particular to S. aureus, S. aureus ATCC 29213, MRSA and S. aureus ATCC 25923 (MICs = 0.6-4.6 nmol/mL), which was more active than norfloxacin (MICs = 6-40 nmol/mL). Subsequent studies showed that 3,6-dibromocarbazole derivative 13a acted rapidly on S. aureus ATCC 29213 and possessed no obvious tendency to induce bacterial resistance. Further evaluations indicated that 3,6-dibromocarbazole derivative 13a showed strong abilities to disrupt bacterial biofilm and interfere with DNA, which might be the power sources of antibacterial performances. Moreover, 3,6-dibromocarbazole derivative 13a also exhibited slight cell lethality toward Hek 293 T and LO2 cells and low hemolytic toxicity to red blood cells. The above results implied that the active molecule 13a could be studied in the future development of agricultural available antibiotics.

Synthesis and Characterization of Telmisartan-Derived Cell Death Modulators to Circumvent Imatinib Resistance in Chronic Myeloid Leukemia

New strategies to eradicate cancer stem cells in chronic myeloid leukemia (CML) include a combination of imatinib with peroxisome proliferator-activated receptor gamma (PPARγ) ligands. Recently, we identified the partial PPARγ agonist telmisartan as effective sensitizer of resistant K562 CML cells to imatinib treatment. Here, the importance of the heterocyclic core on the cell death-modulating effects of the telmisartan-derived lead 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid (3 b) was investigated. Inspired by the pharmacodynamics of HYL-6d and the selective PPARγ ligand VSP-51, the benzimidazole was replaced by a carbazole or an indole core. The results indicate no correlation between PPARγ activation and sensitization of resistant CML cells to imatinib. The 2-COOH derivatives of the carbazoles or indoles achieved low activity at PPARγ, while the benzimidazoles showed 60-100 % activation. Among the 2-CO2 CH3 derivatives, only the ester of the lead (2 b) slightly activated PPARγ. Sensitizing effects were further observed for this non-cytotoxic 2 b (80 % cell death), and to a lesser extent for the lead 3 b or the 5-Br-substituted ester of the benzimidazoles (5 b).

Ginsenoside Rh1 inhibits colorectal cancer cell migration and invasion in vitro and tumor growth in vivo

Colorectal cancer (CRC) is the third leading cause of cancer-associated mortality worldwide. Ginsenoside Rh1 (Rh1) is a traditional medicine monomer with antitumor activity; however, the effects of Rh1 in CRC remain to be determined. In the present study, SW620 cells were treated with different concentrations of Rh1. Cell Counting Kit-8, wound healing and Transwell assays were performed to measure cell viability and proliferation, migration and invasion, respectively. Subsequently, the mRNA expression levels of matrix metallopeptidase (MMP)1, MMP3 and tissue inhibitor of metalloproteinases 3 (TIMP3) were detected by reverse transcription-quantitative PCR analysis. In addition, the protein expression levels of MMP1, MMP3, TIMP3, and total or phosphorylated (p-)ERK1/2, P38, JNK were detected by western blotting. Furthermore, tumor growth was examined in a nude mouse xenograft model. The results of the present study indicated that Rh1 was not toxic to CRC cells at various concentrations (0, 50 or 100 µM) and treatment durations (24 or 48 h). However, cell proliferation was suppressed by Rh1 in a dose-dependent manner. Rh1 (100 µM) significantly inhibited cell migration and invasion in vitro. Additionally, Rh1 suppressed the mRNA and protein expression of MMP1 and MMP3, and promoted TIMP3 expression. Rh1 decreased the ratios of p-P38/P38, p-ERK1/2/ERK1-2 and p-JNK/JNK in vitro and in vivo, which suggested that Rh1 inactivated the mitogen-activated protein kinase (MAPK) signaling pathway. Notably, Rh1 markedly decreased tumor volume and weight in vivo. In conclusion, the present study demonstrated that Rh1 inhibited the proliferation, migration and invasion of CRC cells in vitro and tumor growth in vivo. This inhibition was at least partially due to the inhibition of MMP1 and MMP3 expression, the increase in TIMP3 expression level and the MAPK signaling pathway inactivation. Therefore, Rh1 may effectively inhibit the development of CRC as an anticancer drug, and may have a supporting effect during CRC treatment.

Carbazole scaffolds in cancer therapy: a review from 2012 to 2018

For over half a century, the carbazole skeleton has been the key structural motif of many biologically active compounds including natural and synthetic products. Carbazoles have taken an important part in all the existing anti-cancer drugs because of their discovery from a large variety of organisms, including bacteria, fungi, plants, and animals. In this article, we specifically explored the literature from 2012 to 2018 on the anti-tumour activities reported to carbazole derivatives and we have critically collected the most significant data. The most described carbazole anti-tumour agents were classified according to their structure, starting from the tricyclic–carbazole motif to fused tetra-, penta-, hexa- and heptacyclic carbazoles. To date, three derivatives are available on the market and approved in cancer therapy.

Pro-apoptotic effect of the novel benzylidene derivative MHY695 in human colon cancer cells

The induction of apoptosis is a useful strategy in anti-cancer research. Various Moon Hyung Yang (MHY) compounds have been developed as novel anti-cancer drug candidates; in the present study, the pro-apoptotic effects of (Z)-5-(3-ethoxy-4- hydroxybenzylidene)-2-thioxothiazolidin-4-one (MHY695) on HCT116 human colon cancer cells were assessed. MTT assays were performed to investigate the dose-dependent cytotoxic effects of MHY695 on HCT116 cells. Immunofluorescence staining and flow cytometry analyses were performed to identify apoptotic cell death, and western blot analysis was used to investigate the apoptotic-signaling pathways. A mouse xenograft model was also used to determine the effects of MHY695 in vivo. MHY695 decreased the viability of HCT116 cells and induced apoptotic cytotoxicity. The apoptotic mechanisms induced by MHY695 involved the dephosphorylation of Bcl-2-associated agonist of cell death protein following protein kinase B inactivation, induced myeloid leukaemia cell differentiation protein and BH3-interacting domain death agonist truncation, caspase-3 and -9 activation and poly (ADP-ribose) polymerase cleavage. In addition, MHY695 significantly suppressed tumor growth in the mouse xenograft model, compared with the vehicle control. Notably, MHY695 exhibited potent anti-cancer effects in four different types of human colon cancer cell line, including Caco-2, DLD-1, HT-29 and HCT116. Additionally, MHY695 showed reduced cytotoxicity in NCM460, normal colonic epithelial cells. Furthermore, MHY-induced cytotoxicity in colon cancer cells was independent of the tumor suppressor protein p53. Collectively, these observations suggested that MHY695 may be a novel drug for the treatment of colon cancer.

Identification of Racemic and Chiral Carbazole Derivatives Containing an Isopropanolamine Linker as Prospective Surrogates against Plant Pathogenic Bacteria: In Vitro and In Vivo Assays and Quantitative Proteomics

Recent observations on the emergence of drug-resistant plant pathogenic bacteria have highlighted and elicited an acute campaign to develop novel, highly efficient antibiotic surrogates for managing bacterial diseases in agriculture. Thus, a type of racemic and chiral carbazole derivative containing an isopropanolamine pattern was systematically synthesized to discover low-cost and efficient antibacterial candidates. Screening results showed that compounds 2f, 6c, and 2j could significantly suppress the growth of tested plant pathogens, namely Xanthomonas oryzae pv oryzae, X. axonopodis pv citri, and Pseudomonas syringae pv actinidiae, and provided the corresponding EC₅₀ values of 1.27, 0.993, and 0.603 μg/mL, which were significantly better than those of existing commercial drugs. In vivo studies confirmed their prospective applications for controlling plant bacterial diseases. Label-free quantitative proteomics analysis indicated that compound 2f could dramatically induce the up- and down-regulation of a total of 247 differentially expressed proteins, which was further validated by the parallel reaction monitoring technique. Moreover, fluorescence spectra and SEM images were obtained to further explore the antibacterial mechanism.

Design, synthesis and biological evaluation of new carbazole derivatives as anti-cancer and anti-migratory agents

Based on the efficacy of EHop-016 as an inhibitor of migration and Rac1 activation, a new series of carbazole derivatives has been synthesized. Cytotoxic and anti-migratory effects of these compounds were evaluated in MCF-7 and MDA-MB-231 breast cancer cell lines. Preliminary investigations of their anticancer activity demonstrated that several compounds have moderate antiproliferative effects on cancer cell lines with GI50 values in the range of 13-50 µM. Furthermore, compounds 3b and 11b inhibit migration activity of metastatic cell line MDA-MB-231 by 32% and 34%, respectively. Compound 11b was shown to inhibit activation of the Rho GTPase Rac1 by 55% at 250 nM in both MDA-MB-231 and MDA-MB-435 cell lines. Compared with the IC50 of Rac1 inhibition by lead compound EHop-016 of 1.1 µM, compound 11b demonstrates 4X improved in vitro efficacy.

A combined ligand- and structure-based approach for the identification of rilmenidine-derived compounds which synergize the antitumor effects of doxorubicin

The clonidine-like central antihypertensive agent rilmenidine, which has high affinity for I1-type imidazoline receptors (I1-IR) was recently found to have cytotoxic effects on cultured cancer cell lines. However, due to its pharmacological effects resulting also from α2-adrenoceptor activation, rilmenidine cannot be considered a suitable anticancer drug candidate. Here, we report the identification of novel rilmenidine-derived compounds with anticancer potential and devoid of α2-adrenoceptor effects by means of ligand- and structure-based drug design approaches. Starting from a large virtual library, eleven compounds were selected, synthesized and submitted to biological evaluation. The most active compound 5 exhibited a cytotoxic profile similar to that of rilmenidine, but without appreciable affinity to α2-adrenoceptors. In addition, compound 5 significantly enhanced the apoptotic response to doxorubicin, and may thus represent an important tool for the development of better adjuvant chemotherapeutic strategies for doxorubicin-insensitive cancers.

BC3EE2,9B, a synthetic carbazole derivative, upregulates autophagy and synergistically sensitizes human GBM8901 glioblastoma cells to temozolomide

Glioblastoma multiforme (GBM) is the most fatal form of human brain cancer. Although temozolomide (TMZ), an oral alkylating chemotherapeutic agent, improves the survival rate, the prognosis of patients with GBM remains poor. Naturally occurring carbazole alkaloids isolated from curry leaves (Murraya koenigii Spreng.) have been shown to possess a wide range of anticancer properties. However, the effects of carbazole derivatives on glioblastoma cells remain poorly understood. In the present study, anti-glioblastoma profiles of a series of synthetic carbazole derivatives were evaluated in vitro. The most promising derivative in this series was BC3EE2,9B, which showed significant anti-proliferative effects in GBM8401 and GBM8901 cells. BC3EE2,9B also triggered cell-cycle arrest, most prominently at the G₁ stage, and suppressed glioblastoma cell invasion and migration. Furthermore, BC3EE2,9B induced autophagy-mediated cell death and synergistically sensitized GBM cells to TMZ cytotoxicity. The possible mechanism underlying BC3EE2,9B-induced autophagy may involve activation of adenosine monophosphate-activated protein kinase and the attenuation of the Akt and mammalian target of the rapamycin downstream signaling pathway. Taken together, the present results provide molecular evidence for the mode of action governing the ability of BC3EE2,9B to sensitize drug-resistant glioblastoma cells to the chemotherapeutic agent TMZ.

Thioridazine specifically sensitizes drug-resistant cancer cells through highly increase in apoptosis and P-gp inhibition

This study was designed to identify conditions that induce an increase in the sensitivity of drug-resistant cancer cells compared to sensitive cells. Using cell proliferation assays and microscopic observation, thioridazine (THIO) was found to induce higher sensitization in drug-resistant KBV20C cancer cells compared to sensitive KB parent cells. By studying cleaved PARP, annexin V staining, and Hoechst staining, we found that THIO largely increased apoptosis specifically in KBV20C cells, suggesting that the difference in sensitization between the resistant and sensitive cells can be attributed to the ability of THIO to induce apoptosis. THIO could also inhibit p-glycoprotein (P-gp) activity in the resistant KBV20C cells. These observations suggest that the mechanisms underlying THIO sensitization in resistant KBV20C cells involve both apoptosis and P-gp inhibition. Furthermore, co-treatment with THIO and vinblastine (VIB) induces higher sensitization in KBV20C cells than KB cells. As observed in a single treatment with THIO, the sensitization mechanism induced by the co-treatment also involves both apoptosis and P-gp inhibition. These results suggest that the THIO sensitization mechanism is generally conserved. Our findings may contribute to the development of THIO-based therapies for patients presenting resistance to antimitotic drugs.

Biscarbazolylmethane-based cyanine: a two-photon excited fluorescent probe for DNA and selective cell imaging

We report a novel biscarbazole-based cyanine with a large Stokes shift and TPA cross-section as a light-up probe for DNA and selective TPEF cell imaging.