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Background: Chinese hamster ovarian (CHO) cells are widely employed in biotechnology for the production of recombinant proteins. Extending the life span of CHO cells and inhibiting the loss of producing cell population through the inhibition of apoptosis can benefit the productivity of those cells. In this study, we aimed to screen and evaluate the impact of some caspase-7 inhibitor candidates on the lifespan of CHO cells. Results: Through virtual screening and molecular docking, risperidone was screened and selected as a potential inhibitor of caspase-7 in CHO cells. The results of MTT assay revealed that the cytotoxicity of risperidone at all concentrations was lower than 50%, and thus it can be suggested as a safe treatment for CHO cells. Annexin V apoptosis and flow cytometry assays revealed that risperidone at 1, 25, and 50 µM concentrations inhibited apoptosis 72 h post-treatment through caspase-7 inhibition. Although gene expression analysis through qRT-PCR demonstrates that risperidone did not affect caspase-7 gene expression. Conclusions: This bioinformatics and experimental study suggests risperidone as a caspase-7 inhibitor with the potential to extend the lifespan of CHO cells and offers possible opportunities in biotechnology.How to cite: Kafi S, Najafi S, Mahnam K, et al. Virtual screening and experimental analysis of caspase-7 inhibitors as candidates for extending the lifespan of CHO cells. Electron J Biotechnol 2024;71. https://doi.org/10.1016/j.ejbt.2024.04.007.

Abstract Apoptosis plays a pivotal role in pathogen elimination and maintaining homeostasis. However, viruses have evolved strategies to evade apoptosis, enabling their persistence within the host. Z-DNA binding protein 1 (ZBP1) is a potent innate immune sensor that detects cytoplasmic nucleic acids and activates the innate immune response to clear pathogens. When apoptosis is inhibited by viral invasion, ZBP1 can be activated to compensate for the effect of apoptosis by triggering an innate immune response. This review examined the mechanisms of apoptosis inhibition and ZBP1 activation during viral invasion. The authors outlined the mechanisms of ZBP1-induced type I interferon, pyroptosis and necroptosis, as well as the crosstalk between ZBP1 and the cGAS-STING signalling pathway. Furthermore, ZBP1 can reverse the suppression of apoptotic signals induced by viruses. Intriguingly, a positive feedback loop exists in the ZBP1 signalling pathway, which intensifies the innate immune response while triggering a cytokine storm, leading to tissue and organ damage. The prudent use of ZBP1, which is a double-edged sword, has significant clinical implications for treating infections and inflammation.

Melanoma is the deadliest type of skin cancer. Human melanomas often show hyperactivity of nitric oxide synthase (NOS) and NADPH oxidase (NOX), which, respectively, generate nitric oxide (NO·) and superoxide (O2·−). The NO· and O2− react instantly with each other to generate peroxynitrite (ONOO−) which is the driver of melanin chemiexcitation. Melanoma precursors, the melanocytes, are specialized skin cells that synthesize melanin, a potent shield against sunlight's ultraviolet (UV) radiation. However, melanin chemiexcitation paradoxically demonstrates the melanomagenic properties of melanin. In a loop, the NOS activity regulates melanin synthesis, and melanin is utilized by the chemiexcitation pathway to generate carcinogenic melanin-carbonyls in an excited triplet state. These carbonyl compounds induce UV-specific DNA damage without UV. Additionally, the carbonyl compounds are highly reactive and can make melanomagenic adducts with proteins, DNA and other biomolecules. Here we review the role of the melanin chemiexcitation pathway in melanoma initiation, progression, and drug resistance. We conclude by hypothesizing a non-classical, positive loop in melanoma where melanin chemiexcitation generates carcinogenic reactive carbonyl species (RCS) and DNA damage in normal melanocytes. In parallel, NOS and NOX regulate melanin synthesis generating raw material for chemiexcitation, and the resulting RCS and reactive nitrogen species (RNS) regulate cellular proteome and transcriptome in favor of melanoma progression, metastasis, and resistance against targeted therapies.