Upregulation of apoptotic protease activating factor-1 expression correlates with anti-tumor effect of taxane drug

Monitoring dimer structure orientation of full-length XIAP in living cells using a bioluminescence-based complementation assay

X-chromosome-linked inhibitor of apoptosis protein (XIAP) is a multi-functional protein that performs different roles during cellular processes. Homo- and hetero-dimerization of XIAP plays a critical role in the regulation of cell death signaling and mediating stimulant effects. XIAP-caspase interaction inhibits apoptosis whereas SMAC-XIAP interaction relieves this inhibition. The orientation of XIAP homo-dimerization has not been investigated as full-length so far. In this research, we created a luminescence-based model for real-time monitoring of full-length XIAP-XIAP interaction possibility and its orientation within living cells. Cluc-XIAP, XIAP-Cluc and Nluc-XIAP constructs were generated and expressed in HEK293T cells. We used signal intensity measurement to map out the tendency of two XIAP molecules to bind together and form a dimer. Co-transfection of Nluc-XIAP with Cluc-XIAP showed high level of signal, but no luciferase activity was observed with XIAP-Cluc. Although in presence of both pairs, a substantial decrease was observed in caspase 3/7 activity. Moreover, in Nluc-XIAP/XIAP-Cluc pair, no evidence of a difference was found in cells exposed to docetaxel and bortezomib. Computational analysis suggested that both direct and reverse forms of XIAP dimerization can happen, however experimental results demonstrated that full-length XIAP is capable of forming stable dimers when monomers are oriented in same direction.

Promotion of osteochondral repair through immune microenvironment regulation and activation of endogenous chondrogenesis via the release of apoptotic vesicles from donor MSCs

Utilizing transplanted human umbilical cord mesenchymal stem cells (HUMSCs) for cartilage defects yielded advanced tissue regeneration, but the underlying mechanism remain elucidated. Early after HUMSCs delivery to the defects, we observed substantial apoptosis. The released apoptotic vesicles (apoVs) of HUMSCs promoted cartilage regeneration by alleviating the chondro-immune microenvironment. ApoVs triggered M2 polarization in macrophages while simultaneously facilitating the chondrogenic differentiation of endogenous MSCs. Mechanistically, in macrophages, miR-100-5p delivered by apoVs activated the MAPK/ERK signaling pathway to promote M2 polarization. In MSCs, let-7i-5p delivered by apoVs promoted chondrogenic differentiation by targeting the eEF2K/p38 MAPK axis. Consequently, a cell-free cartilage regeneration strategy using apoVs combined with a decellularized cartilage extracellular matrix (DCM) scaffold effectively promoted the regeneration of osteochondral defects. Overall, new mechanisms of cartilage regeneration by transplanted MSCs were unconcealed in this study. Moreover, we provided a novel experimental basis for cell-free tissue engineering-based cartilage regeneration utilizing apoVs.

Proteomic analysis of holocarboxylase synthetase deficient-MDA-MB-231 breast cancer cells revealed the biochemical changes associated with cell death, impaired growth signaling, and metabolism

We have previously shown that the holocarboxylase synthetase (HLCS) is overexpressed in breast cancer tissue of patients, and silencing of its expression in triple-negative cancer cell line inhibits growth and migration. Here we investigated the global biochemical changes associated with HLCS knockdown in MDA-MB-231 cells to discern the pathways that involve HLCS. Proteomic analysis of two independent HLCS knockdown cell lines identified 347 differentially expressed proteins (DEPs) whose expression change > 2-fold (p < 0.05) relative to the control cell line. GO enrichment analysis showed that these DEPs were mainly associated with the cellular process such as cellular metabolic process, cellular response to stimulus, and cellular component organization or biogenesis, metabolic process, biological regulation, response to stimuli, localization, and signaling. Among the 347 identified DEPs, 64 proteins were commonly found in both HLCS knockdown clones, confirming their authenticity. Validation of some of these DEPs by Western blot analysis showed that plasminogen activator inhibitor type 2 (SerpinB2) and interstitial collagenase (MMP1) were approximately 90% decreased in HLCS knockdown cells, consistent with a 50%-60% decrease in invasion ability of knockdown cells. Notably, argininosuccinate synthase 1 (ASS1), one of the enzymes in the urea cycle, showed approximately a 10-fold increase in the knockdown cells, suggesting the crucial role of HLCS in supporting the urea cycle in the triple-negative cancer cell line. Collectively, our proteomic data provide biochemical insights into how suppression of HLCS expression perturbs global changes in cellular processes and metabolic pathways, impairing cell growth and invasion.

Identification of the phenomenon of anastasis in breast cancer cells

Aim: This study aimed to define the expression changes and potential roles of the apoptosis-related genes in the anastasis process in breast cancer, which is one of the most common cancer types. Materials and Methods: Different types of breast cancer cell lines (MCF7 and MDA-MB-231), breast cancer stem cells, and healthy breast cell line (MCF10A) were used. Apoptotic and anastatic cell percentages were determined by the Annexin V test and flow cytometry. Gene expression changes in anastatic cells compared to apoptotic cells were determined by the qRT-PCR and 2-ΔΔCt method. The pathways and biological processes of genes that show significant changes were determined using the STRING v11.5 database. Results: In all cell groups, it was determined that the percentage of apoptosis increased as a result of ethanol application, and the percentage of apoptotic cells decreased with the removal of the apoptosis-inducing factor. The change in the percentage of apoptotic cells between the control, apoptosis, and anastasis groups was determined the most in MCF7 cells. Consistently, expression changes were determined in the largest number of genes in this cell line. CASP7 and APAF1 genes downregulated in all cell lines. In all cell groups, it was determined that anastasis affects Cysteine-type endopeptidase activity involved in execution phase of apoptosis (GO_ID: 0043027), and drug resistance-related pathways (KEGG_ID: hsa01524). Conclusion: The definition of the interaction of the anastasis phenomenon in cells with apoptosis regulatory mechanisms is important in terms of elucidating both the oncogenic transformation of healthy cells and the mechanisms of drug resistance in cancer.

Inhibition of noncaspase proteases, calpain and proteasome, via ALLN and Bortezomib contributes to cell death through low degradation of pro-/anti-apoptotic proteins and apoptosis induction

Dysfunction at any regulatory point along the apoptotic signaling pathway is closely related to many diseases including cancers. The apoptotic protein expression level is an important cause of cancer-related death, and the correct degradation of apoptotic proteins is involved in tumor development. Therefore, understanding of a regulatory point that underlying cancer-related death may help the development of new strategies to overcome the clinical challenges. Here, proteasome inhibitor Bortezomib and calpain inhibitor ALLN were examined on protein levels of caspase-3, caspase-9, XIAP, and E3-ligase PARC in HEK293T cells overexpressing XIAP and caspase-9. ATP depletion and caspase-3 activation were as a consequence of Bortezomib and ALLN function. Higher numbers of PI-stained cells provided evidence of cell death by both inhibitors. Western blotting analysis showed that both ALLN and Bortezomib equally inhibited degradation of XIAP, but only ALLN was effective at inhibiting caspase proteolytic degradation. Moreover, treatment of cells with both types of inhibitors significantly increased the level of E3-ligase PARC. Our findings showed that inhibition of proteasome and calpains enhanced the level of anti-apoptotic, XIAP and PARC, and pro-apoptotic, caspase-9 and 3 proteins, which totally promote cell death significantly.

Jellyfish as an Alternative Source of Bioactive Antiproliferative Compounds

Jellyfish are commonly considered a nuisance for their negative effects on human activities (e.g., fisheries, power plants and tourism) and human health. However, jellyfish provide several benefits to humans and are commonly eaten in eastern countries. Additionally, recent studies have suggested that jellyfish may become a source of high-value molecules. In this study, we tested the effects of the methanolic extracts and enriched fractions, obtained by solid-phase extraction fractionation, from the scyphomedusae Pelagia noctiluca, Rhizostoma pulmo, Cotylorhiza tuberculata and the cubomedusa Caryddea marsupialis on different human cancer cell lines in order to evaluate a potential antiproliferative activity. Our results indicated that fraction C from Caryddea marsupialis-(CM) and C. tuberculata oral arms (CTOA) were the most active to reduce cell viability in a dose-dependent manner. LC/MS based dereplication analyses highlighted that both bioactive fractions contained mainly fatty acids and derivatives, with CM additionally containing small peptides (0.7–0.8 kDa), which might contribute to its higher biological activity. The mechanism of action behind the most active fraction was investigated using PCR arrays. Results showed that the fraction C of CM can reduce the expression of genes involved in apoptosis inhibition in melanoma-treated cells, which makes jellyfish a potential new source of antiproliferative drugs to be exploited in the future.

Thymoquinone Alterations of the Apoptotic Gene Expressions and Cell Cycle Arrest in Genetically Distinct Triple-Negative Breast Cancer Cells

Breast cancer (BC) is the most common cancer in women worldwide, and it is one of the leading causes of cancer death in women. triple-negative breast Cancer (TNBC), a subtype of BC, is typically associated with the highest pathogenic grade and incidence in premenopausal and young African American (AA) women. Chemotherapy, the most common treatment for TNBC today, can lead to acquired resistance and ineffective treatment. Therefore, novel therapeutic approaches are needed to combat medication resistance and ineffectiveness in TNBC patients. Thymoquinone (TQ) is shown to have a cytotoxic effect on human cancer cells in vitro. However, TQ's mode of action and precise mechanism in TNBC disease in vitro have not been adequately investigated. Therefore, TQ's effects on the genetically different MDA-MB-468 and MDA-MB-231 human breast cancer cell lines were assessed. The data obtained show that TQ displayed cytotoxic effects on MDA-MB-468 and MDA-MB-231 cells in a time- and concentration-dependent manner after 24 h, with IC50 values of 25.37 µM and 27.39 µM, respectively. Moreover, MDA-MB-231 and MDA-MB-468 cells in a scratched wound-healing assay displayed poor wound closure, inhibiting invasion and migration via cell cycle blocking after 24 h. TQ arrested the cell cycle phase in MDA-MB-231 and MDA-MB-468 cells. The three cell cycle stages in MDA-MB-468 cells were significantly affected at 15 and 20 µM for G0/G1 and S phases, as well as all TQ concentrations for G2/M phases. In MDA-MB-468 cells, there was a significant decrease in G0/G1 phases with a substantial increase in the S phase and G2/M phases. In contrast, MDA-MB-231 showed a significant effect only during the two cell cycle stages (S and G2/M), at concentrations of 15 and 20 µM for S phases and all TQ values for G2/M phases. The TQ effect on the apoptotic gene profiles indicated that TQ upregulated 15 apoptotic genes in MDA-MB-231 TNBC cells, including caspases, GADD45A, TP53, DFFA, DIABLO, BNIP3, TRAF2/3, and TNFRSF10A. In MDA-MB-468 cells, 16 apoptotic genes were upregulated, including TNFRSF10A, TNF, TNFRSF11B, FADD TNFRSF10B, CASP2, and TRAF2, all of which are important for the apoptotic pathway andsuppress the expression of one anti-apoptotic gene, BIRC5, in MDA-MB-231 cells. Compared to MDA-MB-231 cells, elevated levels of TNF and their receptor proteins may contribute to their increased sensitivity to TQ-induced apoptosis. It was concluded from this study that TQ targets the MDA-MB-231 and MDA-MB-468 cells differently. Additionally, due to the aggressive nature of TNBC and the lack of specific therapies in chemoresistant TNBC, our findings related to the identified apoptotic gene profile may point to TQ as a potential agent for TNBC therapy.