Novel Hybrid CHC from β-carboline and N-Hydroxyacrylamide Overcomes Drug-Resistant Hepatocellular Carcinoma by Promoting Apoptosis, DNA Damage, and Cell Cycle Arrest

Advances in hepatocellular carcinoma drug resistance models

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Surgery has been the major treatment method for HCC owing to HCC's poor sensitivity to radiotherapy and chemotherapy. However, its effectiveness is limited by postoperative tumour recurrence and metastasis. Systemic therapy is applied to eliminate postoperative residual tumour cells and improve the survival of patients with advanced HCC. Recently, the emergence of various novel targeted and immunotherapeutic drugs has significantly improved the prognosis of advanced HCC. However, targeted and immunological therapies may not always produce complete and long-lasting anti-tumour responses because of tumour heterogeneity and drug resistance. Traditional and patient-derived cell lines or animal models are used to investigate the drug resistance mechanisms of HCC and identify drugs that could reverse the resistance. This study comprehensively reviewed the established methods and applications of in-vivo and in-vitro HCC drug resistance models to further understand the resistance mechanisms in HCC treatment and provide a model basis for possible individualised therapy.

Development of Novel β-Carboline/Furylmalononitrile Hybrids as Type I/II Photosensitizers with Chemo-Photodynamic Therapy and Minimal Toxicity

Chemo-photodynamic therapy is a treatment method that combines chemotherapy and photodynamic therapy and has demonstrated significant potential in cancer treatment. However, the development of chemo-photodynamic therapeutic agents with fewer side effects still poses a challenge. Herein, we designed and synthesized a novel series of β-carboline/furylmalononitrile hybrids 10a-i and evaluated their chemo-photodynamic therapeutic effects. Most of the compounds were photodynamically active and exhibited cytotoxic effects in four cancer cells. In particular, 10f possessed type-I/II photodynamic characteristics, and its 1O2 quantum yield increased by 3-fold from pH 7.4 to 4.5. Most interestingly, 10f exhibited robust antiproliferative effects by tumor-selective cytotoxicities and hypoxic-overcoming phototoxicities. In addition, 10f generated intracellular ROS and induced hepatocellular apoptosis, mitochondrial damage, and autophagy. Finally, 10f demonstrated extremely low acute toxicity (LD50 = 1415 mg/kg) and a high tumor-inhibitory rate of 80.5% through chemo-photodynamic dual therapy. Our findings may provide a promising framework for the design of new photosensitizers for chemo-photodynamic therapy.

Targeting Histone Deacetylases 6 in Dual-Target Therapy of Cancer

Histone deacetylases (HDACs) are the major regulators of the balance of acetylation of histone and non-histone proteins. In contrast to other HDAC isoforms, HDAC6 is mainly involved in maintaining the acetylation balance of many non-histone proteins. Therefore, the overexpression of HDAC6 is associated with tumorigenesis, invasion, migration, survival, apoptosis and growth of various malignancies. As a result, HDAC6 is considered a promising target for cancer treatment. However, none of selective HDAC6 inhibitors are in clinical use, mainly because of the low efficacy and high concentrations used to show anticancer properties, which may lead to off-target effects. Therefore, HDAC6 inhibitors with dual-target capabilities represent a new trend in cancer treatment, aiming to overcome the above problems. In this review, we summarize the advances in tumor treatment with dual-target HDAC6 inhibitors.

3-(1,2,3-Triazol-4-yl)-β-Carbolines and 3-(1H-Tetrazol-5-yl)-β-Carbolines: Synthesis and Evaluation as Anticancer Agents

Herein, the synthesis and anticancer activity evaluation of a series of novel β-carbolines is reported. The reactivity of nitrosoalkenes towards indole was explored for the synthesis of novel tryptophan analogs where the carboxylic acid was replaced by a triazole moiety. This tryptamine was used in the synthesis of 3-(1,2,3-triazol-4-yl)-β-carbolines via Pictet-Spengler condensation followed by an oxidative step. A library of compounds, including the novel 3-(1,2,3-triazol-4-yl)-β-carbolines as well as methyl β-carboline-3-carboxylate and 3-tetrazolyl-β-carboline derivatives, was evaluated for their antiproliferative activity against colorectal cancer cell lines. The 3-(1H-tetrazol-5-yl)-β-carbolines stood out as the most active compounds, with values of half-maximal inhibitory concentration (IC₅₀) ranging from 3.3 µM to 9.6 µM against colorectal adenocarcinoma HCT116 and HT29 cell lines. The results also revealed a mechanism of action independent of the p53 pathway. Further studies with the 3-tetrazolyl-β-carboline derivative, which showed high selectivity for cancer cells, revealed IC₅₀ values below 8 μM against pancreatic adenocarcinoma PANC-1, melanoma A375, hepatocarcinoma HEPG2, and breast adenocarcinoma MCF-7 cell lines. Collectively, this work discloses the 3-tetrazolyl-β-carboline derivative as a promising anticancer agent worthy of being further explored in future works.

Design, synthesis, and biological evaluation of β-carboline 1,3,4-oxadiazole based hybrids as HDAC inhibitors with potential antitumor effects

A series of novel β-carboline 1,3,4-oxadiazole based hybrids were designed, synthesized, and tested for cytotoxicity and HDAC inhibition. Among the target compounds, compound ZDLT-1 displayed high inhibitory activity for class I HDACs 1, 2, and 3, and potent anti-proliferative activity against HCT116 cells with an IC₅₀ value of 0.173 ± 0.018 μM, it also exhibited better inhibitory activity with an IC₅₀ value of 6 nM for HDAC6 than SAHA (IC₅₀ = 15 nM). Furthermore, the pharmacological experiment of Hoechst staining, colony formation, cell apoptosis assay, and wound healing scratch assay indicated that compound ZDLT-1 was a potent cytotoxic agent against HCT116 cells with cell apoptosis induction. Further, in silico prediction of physicochemical properties, drug-likeness, and ADME parameters suggested that compound ZDLT-1 is a promising anticancer agent. Taken together, the high potency cytotoxicity and class I HDACs inhibitory activity of compound ZDLT-1, which with the β-carboline 1,3,4-oxadiazole based hybrids as potent anticancer agents could be nominated for further modification and optimization.

A comprehensive overview of β-carbolines and its derivatives as anticancer agents

β-Carboline alkaloids are a family of natural and synthetic products with structural diversity and outstanding antitumor activities. This review summarizes research developments of β-carboline and its derivatives as anticancer agents, which focused on both natural and synthetic monomers as well as dimers. In addition, the structure-activity relationship (SAR) analysis of β-carboline monomers and dimers are summarized and mechanism of action of β-carboline and its derivatives are also presented. A few possible research directions, suggestions and clues for future work on the development of novel β-carboline-based anticancer agents with improved expected activities and lesser toxicity are also provided.