Cells

SATB2 (special AT-rich binding protein 2) functions as a chromatin-associated epigenetic regulator that modulates gene expression, in part by serving as a transcriptional cofactor. This study assessed whether SATB2 overexpression is sufficient to promote in vitro transformation of human mesothelial cells and whether SATB2 suppression in mesothelioma cancer stem cell (CSC)–enriched populations is associated with altered chemoresistance. SATB2 expression was high in human malignant pleural mesothelioma (MPM) cell lines but absent in Met5A mesothelial cells. Ectopic SATB2 expression in Met5A cells was associated with acquisition of malignant and stem cell–like phenotypes, including increased expression of stem cell markers and pluripotency-associated factors, as well as anchorage-independent growth in soft agar and spheroid formation in suspension culture. In contrast, Met5A cells transduced with an empty vector did not form colonies or mesospheres. SATB2 overexpression in Met5A cells was also associated with increased motility, migration, and invasion, accompanied by induction of epithelial–mesenchymal transition (EMT)–related transcription factors relative to empty vector controls. Conversely, shRNA-mediated SATB2 knockdown in an MPM cell line attenuated proliferation, EMT-associated features, and CSC-like characteristics. Chromatin immunoprecipitation assays identified SATB2 occupancy at promoter regions of Bcl2, XIAP, KLF4, c-Myc, NANOG, and SOX2, consistent with a role in transcriptional regulation of genes linked to transformation, pluripotency, cell survival, proliferation, and EMT. In CSC-enriched cells, SATB2 inhibition was associated with increased sensitivity to cisplatin and pemetrexed, concomitant with reduced OCT4 and SOX2 expression. Collectively, these findings support SATB2 as a candidate therapeutic target in MPM and suggest that SATB2 suppression may enhance chemotherapy response when combined with standard agents.

Nonsense-mediated mRNA decay (NMD) is a highly conserved RNA quality and quantity surveillance machinery in eukaryotic cells, serving as an important node in the post-transcriptional gene expression. Previous studies using the complete knockout of individual NMD factors in cells or animals reveal that NMD deficiency causes developmental defects and compromises tissue homeostasis. However, because most NMD factors participate in multiple molecular functions, a direct link between NMD and cell fate determination is missing. SMG6 is a core NMD effector and the only endoribonuclease among all NMD factors. The NMD function of SMG6 is exclusively mediated by its PIN (PilT N-terminus) domain. In this study, we engineered a mouse model with the capability of specifically deactivating the SMG6’s PIN domain/endoribonuclease activity (Smg6-PIN^F/F), but not knocking out the complete SMG6 protein. We found that SMG6’s PIN domain is essential for NMD activity in embryonic stem cells (ESCs) and various tissues of adult mice. Furthermore, loss of SMG6’s PIN domain is dispensable for the mouse ESC self-renewal, but severely compromises the differentiation, which consequently causes the mutant mice to die during the process of organogenesis. Through the induced deletion of SMG6’s PIN domain in adult mice, we found that loss of SMG6’s NMD function affects the homeostasis of several mouse tissues, including the testis and the intestine. In sum, our study establishes a mechanistic link between NMD per se and cell fate determination of mouse ESCs, as well as in the tissues of adult mice, where cell fate transitions are actively ongoing. The Smg6-PIN^F/F mouse line could be a valuable strain for elucidating the biology of NMD per se.

Ovarian cancer remains one of the leading causes of cancer-related mortality among women, underscoring the need for novel combination strategies that effectively inhibit tumor cell growth while limiting adverse effects. N-acetylcysteine (NAC) and alpha-ketoglutarate (AKG) are biologically active compounds with reported anticancer properties; however, their combined effects in ovarian cancer are not well characterized. In this study, we applied an integrative approach combining network pharmacology analysis with in vitro experiments to investigate the effects of NAC and AKG on OVCAR3 ovarian cancer cells. Common molecular targets of NAC and AKG were identified by intersecting predicted compound targets with ovarian cancer-associated genes, followed by protein–protein interaction network construction and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. Experimental validation assessed the effects of NAC and AKG, alone and in combination, on cell viability, apoptosis, migration, and clonogenic capacity. Network analysis identified 70 shared target genes enriched in pathways related to apoptosis, cellular stress responses, and cell migration. In vitro experiments demonstrated that combined treatment with NAC (10 mM) and AKG (100 µM) significantly reduced cell viability, increased apoptotic cell death, and markedly suppressed cell migration and colony formation compared with single-agent treatments. Overall, these findings indicate that the combination of NAC and AKG exerts enhanced inhibitory effects on ovarian cancer cell growth and motility in vitro.