Apogossypolone induces reactive oxygen species accumulation and controls cell cycle progression in Raji Burkkit’s lymphoma cells

Comprehensive review of Bcl-2 family proteins in cancer apoptosis: Therapeutic strategies and promising updates of natural bioactive compounds and small molecules

Cancer has a considerably higher fatality rate than other diseases globally and is one of the most lethal and profoundly disruptive ailments. The increasing incidence of cancer among humans is one of the greatest challenges in the field of healthcare. A significant factor in the initiation and progression of tumorigenesis is the dysregulation of physiological processes governing cell death, which results in the survival of cancerous cells. B-cell lymphoma 2 (Bcl-2) family members play important roles in several cancer-related processes. Drug research and development have identified various promising natural compounds that demonstrate potent anticancer effects by specifically targeting Bcl-2 family proteins and their associated signaling pathways. This comprehensive review highlights the substantial roles of Bcl-2 family proteins in regulating apoptosis, including the intricate signaling pathways governing the activity of these proteins, the impact of reactive oxygen species, and the crucial involvement of proteasome degradation and the stress response. Furthermore, this review discusses advances in the exploration and potential therapeutic applications of natural compounds and small molecules targeting Bcl-2 family proteins and thus provides substantial scientific information and therapeutic strategies for cancer management.

Inhibition of JAK2/STAT3 Signaling Pathway Suppresses Proliferation of Burkitt's Lymphoma Raji Cells via Cell Cycle Progression, Apoptosis, and Oxidative Stress by Modulating HSP70

Background

The aim of this study was to investigate the effect of the JAK2/STAT3 pathway on the proliferation, cell cycle distribution, apoptosis, and oxidative stress of Raji cells via regulating HSP70 expression.

Material/Methods

Raji cells were divided into Blank, HSP70 siRNA, NC siRNA, AG490 (a JAK2/STAT3 signaling pathway inhibitor), and HSP70 siRNA + rh JAK2 (recombinant human JAK2) groups. HSP70 expression was detected by quantitative real-time reverse transcription-PCR (qRT-PCR); the expression levels of HSP70 and JAK2/STAT3 pathway-related proteins were evaluated by Western blotting; cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays; cell cycle distribution was observed by flow cytometry; cell apoptosis was tested by Annexin V-FITC/PI and Hoechst 33342/PI staining; reactive oxygen species (ROS) production was measured by dichloro-dihydro-fluorescein diacetate (DCFH-DA) assays; and MDA content and SOD and GSH-Px activities were determined using detection kits.

Results

AG490 obviously down-regulated HSP70 expression, inhibited proliferation, induced cell cycle arrest at the G0/G1 phase, and promoted apoptosis in Raji cells; these effects were similar to the effects of HSP70 siRNA. Furthermore, ROS production and MDA content were increased in Raji cells treated with HSP70 siRNA or AG490, while SOD and GSH-Px activities were reduced. Raji cells in the HSP70 siRNA + rh JAK2 group did not significantly differ from those in the Blank group in regards to proliferation, cell cycle, apoptosis, and oxidative stress.

Conclusions

Blocking the JAK2/STAT3 signaling pathway may inhibit proliferation, induce cell cycle arrest, and promote oxidative stress and apoptosis in Raji cells via the down-regulation of HSP70.

Multifaceted anticancer activity of BH3 mimetics: Current evidence and future prospects

BH3 mimetics are a novel class of anticancer agents designed to specifically target pro-survival proteins of the Bcl-2 family. Like endogenous BH3-only proteins, BH3 mimetics competitively bind to surface hydrophobic grooves of pro-survival Bcl-2 family members, counteracting their protective effects and thus facilitating apoptosis in cancer cells. Among the small-molecule BH3 mimetics identified, ABT-737 and its analogs, obatoclax as well as gossypol derivatives are the best characterized. The anticancer potential of these compounds applied as a single agent or in combination with chemotherapeutic drugs is currently being evaluated in preclinical studies and in clinical trials. In spite of promising results, the actual mechanisms of their anticancer action remain to be identified. Findings from preclinical studies point to additional activities of BH3 mimetics in cancer cells that are not connected with apoptosis induction. These off-target effects involve induction of autophagy and necrotic cell death as well as modulation of the cell cycle and multiple cell signaling pathways. For the optimization and clinical implementation of BH3 mimetics, a detailed understanding of their role as inhibitors of the pro-survival Bcl-2 proteins, but also of their possible additional effects is required. This review summarizes the most representative BH3 mimetic compounds with emphasis on their off-target effects. Based on the present knowledge on the multifaceted effects of BH3 mimetics on cancer cells, the commentary outlines the potential pitfalls and highlights the considerable promise for cancer treatment with BH3 mimetics.