The lncRNA ZFAS1 regulates lipogenesis in colorectal cancer by binding polyadenylate-binding protein 2 to stabilize SREBP1 mRNA.
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ABSTRACT:
SUBMITTER: Wang H
PROVIDER: S-EPMC8728310 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Long noncoding RNAs (lncRNAs) have been reported to drive key cancer pathways but the functions of majority of lncRNAs are unknown making a case for comprehensive functional evaluation of lncRNAs. With an aim to identify lncRNAs dysregulated in human cancers, we analyzed the cancer patient database of lung adenocarcinoma (LUAD), which revealed an upregulated lncRNA, LINC02381 (renamed HOXC10mRNA stabilizing factor or HMS in this study), whose depletion results in proliferation defects and inhibition of colony formation of human cancer cells. In order to identify the binding targets of HMS, we screened for cis-genes and discovered that HOXC10, an oncogene, is downregulated in the absence of HMS. Depletion of HMS does not affect the HOXC10 promoter activity but inhibits the HOXC10 3'-UTR-linked luciferase reporter activity. Since lncRNAs have been known to associate with RNA-binding proteins (RBPs) to stabilize mRNA transcripts, we screened for different RBPs and discovered that HuR, an ELAV family protein, stabilizes HOXC10 mRNA. Using RNA pull-down and deletion mapping experiments, we show that HuR physically interacts with the cytosine-rich stretch of HMS and HOXC10 3'-UTR to stabilize HOXC10 mRNA. HOXC10 is overexpressed in many human cancers, and our discovery highlights that lncRNA HMS sustains the HOXC10 mRNA levels to maintain the invasive phenotypes of cancer cells.
| S-EPMC8363838 | biostudies-literature
Project description:Protein kinase B (AKT) hyperactivation and de novo lipogenesis are both common in tumor progression. Sterol regulatory element-binding protein 1 (SREBP1) is the master regulator for tumor lipid metabolism, and protein arginine methyltransferase 5 (PRMT5) is an enzyme that can catalyze symmetric dimethyl arginine (SDMA) modification of the mature form of SREBP1 (mSREBP1) to induce its hyperactivation. Here, we report that SDMA-modified mSREBP1 (mSREBP1-SDMA) was overexpressed and correlated with Ser473-phosphorylated AKT (AKT-473P) expression and poor patient outcomes in human lung adenocarcinomas. Furthermore, patients with AKT-473P and mSREBP1-SDMA coexpression showed the worst prognosis. Mechanistic investigation revealed that AKT activation upregulated SREBP1 at both the transcriptional and post-translational levels, whereas PRMT5 knockdown reversed AKT signaling-mediated mSREBP1 ubiquitin-proteasome pathway stabilization at the post-translational level. Meanwhile, AKT activation promoted nuclear PRMT5 to the cytoplasm without changing total PRMT5 expression, and the transported cytoplasmic PRMT5 (cPRMT5) induced by AKT activation showed a strong mSREBP1-binding ability. Immunohistochemical assay indicated that AKT-473P and mSREBP1-SDMA were positively correlated with cPRMT5 in lung adenocarcinomas, and high cPRMT5 levels in tumors were associated with poor patient outcomes. Additionally, PRMT5 knockdown reversed AKT activation-induced lipid synthesis and growth advantage of lung adenocarcinoma cells both in vitro and in vivo. Finally, we defined an AKT/PRMT5/SREBP1 axis involved in de novo lipogenesis and the growth of lung cancer. Our data also support that cPRMT5 is a potential therapeutic target for hyperactive AKT-driven lung adenocarcinoma.
| S-EPMC8353903 | biostudies-literature
Project description:The aberrantly increased lipogenesis is a universal metabolic feature of proliferating tumor cells. Although most normal cells acquire the bulk of their fatty acids from circulation, tumor cells synthesize more than 90% of required lipids de novo. The sterol regulatory element-binding protein 1 (SREBP1), encoded by SREBF1 gene, is a master regulator of lipogenic gene expression. SREBP1 and its target genes are overexpressed in a variety of cancers; however, the role of SREBP1 in endometrial cancer is largely unknown. We have screened a cohort of endometrial cancer (EC) specimen for their lipogenic gene expression and observed a significant increase of SREBP1 target gene expression in cancer cells compared with normal endometrium. By using immunohistochemical staining, we confirmed SREBP1 protein overexpression and demonstrated increased nuclear distribution of SREBP1 in EC. In addition, we found that knockdown of SREBP1 expression in EC cells suppressed cell growth, reduced colonigenic capacity and slowed tumor growth in vivo. Furthermore, we observed that knockdown of SREBP1 induced significant cell death in cultured EC cells. Taken together, our results show that SREBP1 is essential for EC cell growth both in vitro and in vivo, suggesting that SREBP1 activity may be a novel therapeutic target for endometrial cancers.
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Project description:BackgroundLong non-coding RNAs (lncRNAs) perform a vital role during the progression of hepatocellular carcinoma (HCC). Here, we aimed to identify a novel lncRNA involved in HCC development and elucidate the underlying molecular mechanism.MethodsThe RT-qPCR and TCGA dataset analysis were applied to explore the expressions of MRVI1-AS1 in HCC tissues and cell lines. Statistical analysis was applied to analyze the clinical significance of MRVI1-AS1 in HCC. The functions of MRVI1-AS1 in HCC cells metastasis and growth were explored by transwell assays, wound healing assay, MTT assay, EdU assay, the intravenous transplantation tumor model, and the subcutaneous xenograft tumor model. Microarray mRNA expression analysis, dual luciferase assays, and actinomycin D treatment were used to explore the downstream target of MRVI1-AS1 in HCC cells. RIP assay was applied to assess the direct interactions between CELF2 and MRVI1-AS1 or SKA1 mRNA. Rescue experiments were employed to validate the functional effects of MRVI1-AS1, CELF2, and SKA1 on HCC cells.ResultsMRVI1-AS1 was found to be dramatically upregulated in HCC and the expression was strongly linked to tumor size, venous infiltration, TNM stage, as well as HCC patients' outcome. Cytological experiments and animal experiments showed that MRVI1-AS1 promoted HCC cells metastasis and growth. Furthermore, SKA1 was identified as the downstream targeted mRNA of MRVI1-AS1 in HCC cells, and MRVI1-AS1 increased SKA1 expression by recruiting CELF2 protein to stabilize SKA1 mRNA. In addition, we found that MRVI1-AS1 expression was stimulated by hypoxia through a HIF-1-dependent manner, which meant that MRVI1-AS was a direct downstream target gene of HIF-1 in HCC.ConclusionIn a word, our findings elucidated that hypoxia-induced MRVI1-AS1 promotes metastasis and growth of HCC cells via recruiting CELF2 protein to stabilize SKA1 mRNA, pointing to MRVI1-AS1 as a promising clinical application target for HCC therapy.
| S-EPMC10044719 | biostudies-literature
Project description:Increasing long non-coding RNAs (lncRNAs) have been reported to play key roles in the development and progression of various malignancies. ZNFX1 antisense RNA1 (ZFAS1) has been reported to be aberrant expression and suggested as a tumor suppressor or oncogene in many cancers. However, the biological role and underlying molecular mechanism of ZFAS1, especially the miRNA sponge role of which in CRC remain largely unknown. We found that ZFAS1 expression was higher in CRC tissues, where it was associated with poor overall survival (OS), we also showed that ZFAS1 upregulation was induced by nuclear transcription factor SP1. Moreover, ZFAS1 and VEGFA are both targets of miR-150-5p, while ZFAS1 binds to miR-150-5p in an AGO2-dependent manner. Additionally, ZFAS1 upregulation markedly promoted as well as ZFAS1 knockdown significantly suppressed CRC cell proliferation, migration, invasion and angiogenesis, and the inhibitory effect caused by ZFAS1 knockdown could be reversed by antagomiR-150-5p. Lastly, we demonstrated that ZFAS1 knockdown inhibited EMT process and inactivated VEGFA/VEGFR2 and downstream Akt/mTOR signaling pathway in CRC. Our data demonstrated that SP1-induced ZFAS1 contributed to CRC progression by upregulating VEGFA via competitively binding to miR-150-5p, which acts as a tumor suppressor by targeting VEGFA in CRC.
| S-EPMC6155123 | biostudies-literature
Project description:The hereditary information encoded in DNA sequence is intrinsically susceptible to alterations, being continually threatened by a variety of genotoxic perturbations. To safeguard the stability of the genome, eukaryotic cells have evolved a set of sophisticated surveillance system that controls several aspects of the cellular response, including the detection of DNA lesions, a temporary cell cycle arrest, regulation of transcription, and the repair of the damaged DNA. However, it is still poorly understood how the DNA damage checkpoints and stalled RNAPII molecules convert a very limited amount of molecular-level information (even a single DNA lesion) in the context of an otherwise genome into regulation that halts and resumes the cell-cycle engine in a coordinated way. In this study, we reveal a map of extensive lncRNA transcription during DDR by using synchronized cells, leading to the unexpected identification of a poorly characterized mammalian lncRNA-ZFAS1. We describe that ZFAS1 functions as a key player of cellular response to DNA damage in both human and rodent cells by fine tuning RNAPII kinetics, suggesting a lncRNA-dependent transcriptional regulatory axis that maintains genomic stability upon DNA damage in mammalian cells.
2023-08-03 | GSE239615 | GEO
Project description:Emergence of acquired resistance to osimertinib (AZD9291), the first-approved third-generation EGFR inhibitor that selectively and irreversibly inhibits the activating EGFR mutations and the resistant T790M mutation, is a giant and urgent clinical challenge. Fully understanding the biology underlying the response of EGFR mutant non-small cell lung cancer (NSCLC) to osimertinib is the foundation for development of mechanism-driven strategies to overcome acquired resistance to osimertinib or other third-generation EGFR inhibitors. This study focused on tackling this important issue by elucidating the critical role of sterol regulatory element-binding protein 1 (SREBP1) degradation in conferring the response of EGFR mutant NSCLC cells to osimertinib and by validating the strategy via directly targeting SREBP1 for overcoming osimertinib acquired resistance. Osimertinib facilitated degradation of the mature form of SREBP1 (mSREBP1) in a GSK3/FBXW7-dependent manner and reduced protein levels of its regulated genes in EGFR-mutant NSCLC cells/tumors accompanied with suppression of lipogenesis. Once resistant, EGFR-mutant NSCLC cell lines possessed elevated levels of mSREBP1, which were resistant to osimertinib modulation. Both genetic and pharmacological inhibition of SREBP1 sensitized osimertinib-resistant cells and tumors to osimertinib primarily through enhancing Bim-dependent induction of apoptosis, whereas enforced expression of ectopic SREBP1 in sensitive EGFR-mutant NSCLC cells compromised osimertinib's cell-killing effects. Collectively, we have demonstrated a novel connection between osimertinib and SREBP1 degradation and its impact on the response of EGFR mutant NSCLC cells to osimertinib and suggested an effective strategy for overcoming acquired resistance to osimertinib, and possibly other EGFR inhibitors, via targeting SREBP1.
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Project description:The aryl hydrocarbon receptor (AHR) mediates 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) induced toxicity that can lead to chloracne in humans. A characteristic of chloracne, in contrast to acne vulgaris, is shrinkage or loss of sebaceous glands. Acne vulgaris, on the other hand, is often accompanied by excessive sebum production. Here, we examined the role of AHR in lipid synthesis in human sebocytes using distinct classes of AHR ligands. Modulation of AHR activity attenuated the expression of lipogenic genes and key pro-inflammatory markers in the absence of canonical DRE-driven transcription of the AHR target gene CYP1A1. Furthermore, topical treatment with TCDD, which mediates DRE-dependent activity, and SGA360, which fails to induce DRE-mediated responses, both exhibited a decrease in the size of sebaceous glands and the number of sebocytes within each gland in the skin. To elucidate the mechanism of AHR-mediated repression of lipid synthesis, we demonstrated that selective AHR modulators, SGA360 and SGA315 increased the protein turnover of the mature sterol regulatory element-binding protein (mSREBP-1), the principal transcriptional regulator of the fatty acid synthesis pathway. Interestingly, selective AHR ligand treatment significantly activated the AMPK-dependent kinase (AMPK) in sebocytes. Moreover, we demonstrated an inverse correlation between the active AMPK and the mSREBP-1 protein, which is consistent with the previously reported role of AMPK in inhibiting cleavage of SREBP-1. Overall, our findings indicate a DRE-independent function of selective AHR ligands in modulating lipid synthesis in human sebocytes, which might raise the possibility of using AHR as a therapeutic target for treatment of acne.
| S-EPMC6736396 | biostudies-literature
Project description:Proper regulation of sebum production is important for maintaining skin homeostasis in humans. However, little is known about the role of epigenetic regulation in sebocyte lipogenesis. We investigated histone acetylation changes and their role in key lipogenic gene regulation during sebocyte lipogenesis using the human sebaceous gland cell line SZ95. Sebocyte lipogenesis is associated with a significant increase in histone acetylation. Treatment with anacardic acid (AA), a p300 histone acetyltransferase inhibitor, significantly decreased the lipid droplet number and the expression of key lipogenic genes, including sterol regulatory-binding protein 1 (SREBP1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). In contrast, treatment with trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, increased the expression of these genes. Global HDAC enzyme activity was decreased, and HDAC1 and HDAC2 expression was downregulated during sebaceous lipogenesis. Interestingly, HDAC1 knockdown increased lipogenesis through SREBP1 induction, whereas HDAC1 overexpression decreased lipogenesis and significantly suppressed SREBP1 promoter activity. HDAC1 and SREBP1 levels were inversely correlated in human skin sebaceous glands as demonstrated in immunofluorescence images. In conclusion, HDAC1 plays a critical role in reducing SREBP1 transcription, leading to decreased sebaceous lipogenesis. Therefore, HDAC1 activation could be an effective therapeutic strategy for skin diseases related to excessive sebum production.
| S-EPMC8123291 | biostudies-literature
Project description:Protein kinase D (PKD) has been implicated in cancer cell survival, proliferation, migration and angiogenesis. However, it is still unknown whether PKD regulates cell proliferation through lipid metabolism in cancer cells. Here we report a novel function of PKD3, a member of PKD family, in regulating of prostate cancer cell proliferation by modulation of SREBP1-mediated de novo lipogenesis. We show that silencing of PKD3 significantly reduces lipid content and expression of the lipogenic genes encoding FASN and ATP-citrate lyase (ACLY). Moreover, endogenous PKD3 interacts with sterol regulatory element binding protein 1(SREBP1) in DU145 cells. Interestingly, PKD3 silencing decreases not only the level of matured-SREBP1 (68KD) but also the binding of SREBP1 to the promoter of fasn gene. In addition, overexpression of SREBP1 reverses the suppression of cell growth caused by PKD3 depletion. Finally, immune-histochemical staining indicate that PKD3 expression is positively correlated with expression of FASN and SREBP1 in prostate cancers. Taken together, these data suggest that targeting PKD3-mediated de novo lipogenesis may be a potential therapeutic approach to block prostate cancer progression.
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