Noncanonical role of singleminded-2s in mitochondrial respiratory chain formation in breast cancer.
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ABSTRACT:
SUBMITTER: Wall SW
PROVIDER: S-EPMC10238511 | biostudies-literature | 2023 May
REPOSITORIES: biostudies-literature
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Project description:Singleminded-2s (SIM2s) is a member of the bHLH/PAS family of transcription factors and a key regulator of mammary epithelial cell differentiation. SIM2s is highly expressed in mammary epithelial cells and downregulated in human breast cancer. Loss of Sim2s causes aberrant mouse mammary ductal development, with features suggestive of malignant transformation, whereas overexpression of SIM2s promotes precocious alveolar differentiation in nulliparous mouse mammary glands, suggesting that SIM2s is required for establishing and enhancing mammary gland differentiation. To test the hypothesis that SIM2s regulates tumor cell differentiation, we analyzed SIM2s expression in human primary breast ductal carcinoma in situ (DCIS) samples and found that SIM2s is lost with progression from DCIS to invasive ductal cancer (IDC). Using a MCF10DCIS.COM progression model, we have shown that SIM2s expression is decreased in MCF10DCIS.COM cells compared with MCF10A cells, and reestablishment of SIM2s in MCF10DCIS.COM cells significantly inhibits growth and invasion both in vitro and in vivo. Analysis of SIM2s-MCF10DCIS.com tumors showed that SIM2s promoted a more differentiated tumor phenotype including the expression of a broad range of luminal markers (CSN2 (β-casein), CDH1 (E-cadherin), and KER18 (keratin-18)) and suppressed genes associated with stem cell maintenance and a basal phenotype (SMO (smoothened), p63, SLUG (snail-2), KER14 (keratin-14) and VIM (vimentin)). Furthermore, loss of SIM2s expression in MCF10DCIS.COM xenografts resulted in a more invasive phenotype and increased lung metastasis likely due to an increase in Hedgehog signaling and matrix metalloproteinase expression. Together, these exciting new data support a role for SIM2s in promoting human breast tumor differentiation and maintaining epithelial integrity.
| S-EPMC4469191 | biostudies-literature
Project description:We have previously demonstrated that the bHLH/PAS transcription factor, singleminded 2s (Sim2s), is required for proper mammary ductal morphogenesis and luminal epithelial differentiation. Furthermore, loss of Sim2s in breast cancer cells resulted in downregulation of epithelial markers and acquisition of a basal-like phenotype. The objective of this study was to further define the role of Sim2s in mammary differentiation. We found that Sim2s is developmentally regulated throughout mammary gland development with highest expression during lactation. Mammary glands from nulliparous mice expressing Sim2s driven by the mouse mammary tumor virus (MMTV) long terminal repeat (LTR) promoter were morphologically indistinguishable from wild-type mice but displayed hallmarks of precocious lactogenic differentiation. These included elevated expression of the milk protein genes Wap and Csn2, and apical localization of the lactation marker Npt2b. Consistent with the in vivo results, Sim2s enhanced prolactin-mediated Csn2 expression in HC11 and CIT3 mouse mammary epithelial cells, and downregulation of Sim2s by shRNA in HC11 cells inhibited Csn2 expression. Chromatin immunoprecipitation (ChIP) analyses of the Csn2 gene found that Sim2s associates with the Csn2 promoter and re-ChIP experiments showed that Sim2s interacted with the RNA II polymerase (RNAPII) complex. Together, these data demonstrate, for the first time, that Sim2s is required for establishing and maintaining mammary gland differentiation.
| S-EPMC2834457 | biostudies-literature
Project description:Mammalian mitochondrial respiratory chain (MRC) complexes are able to associate into quaternary structures named supercomplexes (SCs), which normally coexist with non-bound individual complexes. The functional significance of SCs has not been fully clarified and the debate has been centered on whether or not they confer catalytic advantages compared with the non-bound individual complexes. Mitochondrial respiratory chain organization does not seem to be conserved in all organisms. In fact, and differently from mammalian species, mitochondria from Drosophila melanogaster tissues are characterized by low amounts of SCs, despite the high metabolic demands and MRC activity shown by these mitochondria. Here, we show that attenuating the biogenesis of individual respiratory chain complexes was accompanied by increased formation of stable SCs, which are missing in Drosophila melanogaster in physiological conditions. This phenomenon was not accompanied by an increase in mitochondrial respiratory activity. Therefore, we conclude that SC formation is necessary to stabilize the complexes in suboptimal biogenesis conditions, but not for the enhancement of respiratory chain catalysis.
| S-EPMC10569793 | biostudies-literature
Project description:Mitochondrial membrane phospholipid composition affects mitochondrial function by influencing the assembly of the mitochondrial respiratory chain (MRC) complexes into supercomplexes. For example, the loss of cardiolipin (CL), a signature non-bilayer-forming phospholipid of mitochondria, results in disruption of MRC supercomplexes. However, the functions of the most abundant mitochondrial phospholipids, bilayer-forming phosphatidylcholine (PC) and non-bilayer-forming phosphatidylethanolamine (PE), are not clearly defined. Using yeast mutants of PE and PC biosynthetic pathways, we show a specific requirement for mitochondrial PE in MRC complex III and IV activities but not for their formation, whereas loss of PC does not affect MRC function or formation. Unlike CL, mitochondrial PE or PC is not required for MRC supercomplex formation, emphasizing the specific requirement of CL in supercomplex assembly. Of interest, PE biosynthesized in the endoplasmic reticulum (ER) can functionally substitute for the lack of mitochondrial PE biosynthesis, suggesting the existence of PE transport pathway from ER to mitochondria. To understand the mechanism of PE transport, we disrupted ER-mitochondrial contact sites formed by the ERMES complex and found that, although not essential for PE transport, ERMES facilitates the efficient rescue of mitochondrial PE deficiency. Our work highlights specific roles of non-bilayer-forming phospholipids in MRC function and formation.
| S-EPMC4945136 | biostudies-literature
Project description:Primary mitochondrial respiratory chain (RC) diseases are heterogeneous in etiology and manifestations but collectively impair cellular energy metabolism. To identify a common cellular response to RC disease, systems biology level transcriptome investigations were performed in human RC disease skeletal muscle and fibroblasts. Global transcriptional and post-transcriptional dysregulation in a tissue-specific fashion was identified across diverse RC complex and genetic etiologies. RC disease muscle was characterized by decreased transcription of cytosolic ribosomal proteins to reduce energy-intensive anabolic processes, increased transcription of mitochondrial ribosomal proteins, shortened 5'-UTRs to improve translational efficiency, and stabilization of 3'-UTRs containing AU-rich elements. These same modifications in a reversed direction typified RC disease fibroblasts. RC disease also dysregulated transcriptional networks related to basic nutrient-sensing signaling pathways, which collectively mediate many aspects of tissue-specific cellular responses to primary RC disease. These findings support the utility of a systems biology approach to improve mechanistic understanding of mitochondrial RC disease. To identify a common cellular response to primary RC that might improve mechanistic understanding and lead to targeted therapies for human RC disease, we performed collective transcriptome profiling in skeletal muscle biopsy specimens and fibroblast cell lines (FCLs) of a diverse cohort of human mitochondrial disease subjects relative to controls. Systems biology investigations of common cellular responses to primary RC disease revealed a collective pattern of transcriptional, post-transcriptional and translational dysregulation occurring in a highly tissue-specific fashion. Affymetrix Human Exon 1.0ST microarray analysis was performed on 29 skeletal muscle samples and Fibroblast cell lines from mitochondrial disease patients and age- and gender-matched controls.
2013-07-01 | E-GEOD-42986 | biostudies-arrayexpress
Project description:AimHistone deacetylase inhibitors (HDACIs)-based therapies have stimulated interest via their anti-tumor activities, including apoptosis induction, cell cycle arrest, cell differentiation, and autophagy. However, the mechanisms of HDACI-associated anti-tumor activity are not yet clearly defined. The aim of this study was to explore the key events of Trichostatin A (TSA), a classic HDACI agent, against breast cancer cells.MethodsThe MCF-7, MDA-MB-231 and MCF-10A cell lines were evaluated with colony-forming and cell viability assays. Apoptosis and cell cycle distribution were detected by flow cytometry. Mitochondrial function was measured with biochemical assays, flow cytometry and transmission electron microscopy.ResultsTSA inhibited breast cancer cell viability and proliferation, without affecting MCF-10A cell. TSA-induced breast cancer cell apoptosis was initiated by G2-M arrest and depended on mitochondrial reactive oxygen species (ROS) produced subsequent to reduced mitochondrial respiratory chain activity. The enhanced mitochondrial ROS production and apoptosis in cancer cells were markedly attenuated by antioxidants, such as N-acetyl cysteine (NAC), reduced glutathione (GSH) and Vitamin C.ConclusionThe present study demonstrated that TSA-induced cell death by arresting cell cycle in G2-M phase and was dependent on production of mitochondria-derived ROS, which was derived from impaired mitochondrial respiratory chain.
| S-EPMC3953478 | biostudies-literature
Project description:Postlactational involution of the mammary gland provides a unique model to study breast cancer susceptibility and metastasis. We have shown that the short isoform of Singleminded-2s (Sim2s), a basic helix loop helix/PAS transcription factor, plays a role in promoting lactogenic differentiation, as well as maintaining mammary epithelial differentiation and malignancy. Sim2s is dynamically expressed during mammary gland development, with expression peaking during lactation, and decreasing in early involution. To determine the role of SIM2S in involution, we used transgenic mice expressing SIM2S under the mouse mammary tumor virus-Sim2s promoter. Overexpression of Sim2s in the mouse mammary gland resulted in delayed involution, indicated by a lower proportion of cleaved caspase-3-positive cells and slower reestablishment of the mammary fat pad. Immunohistochemical and quantitative RNA analysis showed a decrease in apoptotic markers and inflammatory response genes, and an increase in antiapoptotic genes, which were accompanied by inhibition of signal transducer and activator of transcription 3 activity. Microarray analysis confirmed that genes in the signal transducer and activator of transcription 3 signaling pathway were repressed by SIM2S expression, along with nuclear factor-κB and other key pathways involved in mammary gland development. Multiparous mouse mammary tumor virus-Sim2s females displayed a more differentiated phenotype compared with wild-type controls, characterized by enhanced β-casein expression and alveolar structures. Together, these results suggest a role for SIM2S in the normal involuting gland and identify potential downstream pathways regulated by SIM2S.
| S-EPMC3386548 | biostudies-literature
Project description:We have previously shown that Singleminded-2s (SIM2s), a member of the basic helix-loop-helix Per-Arnt-Sim (bHLH/PAS) family of transcription factors, is downregulated in breast cancer samples and has tumor suppressor activity. However, the mechanism by which SIM2s is repressed in breast cancer cells has not been determined. In this study, we show that transformation of MCF10A cells by Harvey-Ras (Ha-Ras) induces CCAAT/enhance binding protein beta (C/EBPbeta) and activates the NOTCH signaling pathway to block SIM2s gene expression. NOTCH-mediated repression acts through a C-repeat binding factor 1 (CBF1)-independent mechanism, as introduction of CBF1 had no effect on SIM2s expression. Consistent with C/ebpbeta-dependent inhibition of SIM2s, C/ebpbeta(-/-) mouse mammary glands express high levels of SIM2s and reestablishment of C/ebpbeta isoforms decreased SIM2s mRNA levels in C/ebpbeta immortalized mammary epithelial cell lines. These studies illustrate a novel pathway of tumor suppressor gene silencing in Ha-Ras-transformed breast epithelial cells and identify SIM2s as a target of C/EBPbeta and NOTCH signaling.
| S-EPMC2692552 | biostudies-literature
Project description:Post-lactational involution of the mammary gland provides a unique model to study breast cancer susceptibility and metastasis. We have shown that the short isoform of Singleminded-2 (Sim2s), a bHLH/PAS transcription factor, plays a role in promoting lactogenic differentiation, as well as in maintaining mammary epithelial differentiation and malignancy. Sim2s is dynamically expressed during mammary gland development, with expression peaking during lactation, and decreasing in early involution. To determine the role of Sim2s in involution, we used transgenic mice expressing Sim2s under the mouse mammary tumor virus (MMTV-Sim2s) promoter. Over-expression of Sim2s in the mouse mammary gland resulted in delayed involution, indicated by a lower proportion of cleaved caspase-3 positive cells and slower re-establishment of the mammary fat pad. Immunohistochemical and quantitative RNA analysis showed a decrease in apoptotic markers and inflammatory response genes, and an increase in anti-apoptotic genes, which were accompanied by inhibition of signal transducer and activator of transcription 3 (Stat3) activity. Microarray analysis confirmed that genes in the Stat3 signaling pathway were repressed by Sim2s expression, along with NFκB and other key pathways involved in mammary gland development. Multiparous MMTV-Sim2s females displayed a more differentiated phenotype compared to wild-type controls, characterized by enhanced β-casein expression and alveolar structures. Together, these results suggest a role for Sim2s in the normal involuting gland, and identify potential down-stream pathways regulated by Sim2s.
2011-02-03 | GSE27012 | GEO
Project description:In this study, we investigate how mitochondrial thiamine pyrophosphate (TPP) transporter SLC25A19 regulates mitochondrial function and cell metabolism.
2025-03-31 | GSE253270 | GEO