Effects of CD44 siRNA on inhibition, survival, and apoptosis of breast cancer cell lines (MDA-MB-231 and 4T1).

BACKGROUND: Breast cancer (BC) is one of the most common cancers in the world. Despite the many advances that have been made in treating patients, many patients are still resistant to treatment. CD44 is one of the surface glycoproteins of BC cells that plays an important role in the proliferation of these cells and inhibition of their apoptosis. Therefore, targeting it can be a treatment way for BC patients. METHODS: In this study, the effect of anti-CD44 siRNA on the proliferation, apoptosis, and migration rate of MDA-MB-231 and 4T1 cells was investigated. The techniques used in this study were MTT assay, RT-PCR, and flow cytometry. RESULTS: The apoptosis and proliferation rates in CD44 siRNA-treated cells were higher and lower, respectively, compared to untreated cells. Also, cell migration was less in treated cells compared to untreated cells. CD44 siRNA also decreased the expression of CXCR4, c-myc, Vimentin, ROCK, and MMP-9. CONCLUSION: Finally, CD44 targeting can be a good treatment option to make BC cells more sensitive to apoptosis.

MicroRNA-671-5p regulates the inflammatory response of periodontal ligament stem cells via the DUSP8/p38 MAPK pathway.

BACKGROUND: MicroRNAs are differentially expressed in periodontitis tissues. They are involved in cellular responses to inflammation and can be used as markers for diagnosing periodontitis. Microarray analysis showed that the expression level of microRNA-671-5p in periodontal tissues of patients with periodontitis was increased. In this study, we investigated the mechanism of action of microRNA-671-5p in human periodontal ligament stem cells (hPDLSCs) under inflammatory conditions. METHODS AND RESULTS: HPDLSCs were treated with lipopolysaccharide (LPS) to establish an inflammation model. The cell survival rate was determined using the cell counting kit-8 (CCK8). Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses were used to detect the expression of microRNA-671-5p and dual-specificity phosphatase (DUSP) 8 proteins, respectively, Interleukin (IL)-6, IL-1ß, and tumor necrosis factor (TNF)-α were detected using qRT-PCR and Enzyme-linked immunosorbent assay (ELISA). A dual-luciferase reporter system was employed to determine the relationship between micoRNA-671-5p and DUSP8 expression. Activation of the p38 mitogen-activated protein kinase (MAPK) signaling pathway was confirmed using western blot analysis. Following the treatment of hPDLSCs with LPS, the expression levels of microRNA-671-5p in hPDLSCs were increased, cell viability decreased, and the expression of inflammatory factors displayed an increasing trend. MicroRNA-671-5p targets and binds to DUSP8. Silencing microRNA-671-5p or overexpressing DUSP8 can improve cell survival rate and reduce inflammatory responses. When DUSP8 was overexpressed, the expression of p-p38 was reduced. CONCLUSIONS: microRNA-671-5p targets DUSP8/p38 MAPK pathway to regulate LPS-induced proliferation and inflammation in hPDLSCs.

Pseudogene CSPG4P12 inhibits colorectal cancer progression by attenuating epithelial-mesenchymal transition.

Colorectal cancer is one of the most common malignant cancers. Pseudogenes have been identified as oncogenes or tumor suppressor genes in the development of various cancers. However, the function of pseudogene CSPG4P12 in colorectal cancer remains unclear. Therefore, the aim of this study was to investigate the potential role of CSPG4P12 in colorectal cancer and explore the possible underlying mechanism. The difference of CSPG4P12 expression between colorectal cancer tissues and adjacent normal tissues was analyzed using the online Gene Expression Profiling Interactive Analysis 2 (GEPIA2) database. Cell viability and colony formation assays were conducted to evaluate cell viability. Transwell and wound healing assays were performed to assess cell migration and invasion capacities. Western blot was used to measure the expression levels of epithelial-mesenchymal transition-related proteins. Colorectal cancer tissues had lower CSPG4P12 expression than adjacent normal tissues. The overexpression of CSPG4P12 inhibited cell proliferation, invasion, and migration in colorectal cancer cells. Overexpressed CSPG4P12 promoted the expression of E-cadherin, whereas it inhibited the expression of vimentin, N-cadherin, and MMP9. These findings suggested that CSPG4P12 inhibits colorectal cancer development and may serve as a new potential target for colorectal cancer.

ELF3 plays an important role in defining TRAIL sensitivity in breast cancer by modulating the expression of decoy receptor 2 (DCR2).

BACKGROUND: TRAIL protein on binding to its cognate death receptors (DR) can induce apoptosis specifically in breast tumor cells sparing normal cells. However, TRAIL also binds to decoy receptors (DCR) thereby inhibiting the apoptotic pathways thus causing TRAIL resistance. Also, one of the barriers due to which TRAIL-based therapy could not become FDA-approved might be because of resistance to therapy. Therefore, in the current study we wanted to explore the role of transcription factors in TRAIL resistance with respect to breast cancer. METHODS: Microarray data from TRAIL-sensitive (TS) and TRAIL-resistant (TR) MDA-MB-231 cells were reanalyzed followed by validation of the candidate genes using quantitative PCR (qPCR), immunoblotting and immunofluorescence technique. Overexpression of the candidate gene was performed in MDA-MB-231 and MCF7 cells followed by cell viability assay and immunoblotting for cleaved caspase-3. Additionally, immunoblotting for DCR2 was carried out. TCGA breast cancer patient survival was used for Kaplan-Meier (KM) plot. RESULTS: Validation of the candidate gene i.e. ELF3 using qPCR and immunoblotting revealed it to be downregulated in TR cells compared to TS cells. ELF3 overexpression in MDA-MB-231 and MCF7 cells caused reversal of TRAIL resistance as observed using cell viability assay and cleaved caspase-3 immunoblotting. ELF3 overexpression also resulted in DCR2 downregulation in the MDA-MB-231 and MCF7 cells. Furthermore, KM analysis found high ELF3 and low DCR2 expression to show better patient survival in the presence of TRAIL. CONCLUSION: Our study shows ELF3 to be an important factor that can influence TRAIL-mediated apoptosis in breast cancer. Also, ELF3 and DCR2 expression status should be taken into consideration while designing strategies for successful TRAIL-based therapy.

METTL3-mediated m6A methylation of SLC38A1 stimulates cervical cancer growth.

The objective of this study was to better characterize the role of the glutamine transporter SLC38A1 in cervical cancer and explore the underlying mechanisms. Data from public databases and clinical cervical cancer tissue samples were used to assess the expression of SLC38A1 and its prognostic significance. Immunohistochemical staining, qRT-PCR, and Western blotting were used to evaluate the expression of relevant genes and proteins. Cell viability, cell cycle, apoptosis, and intracellular glutamine content were measured using CCK-8, flow cytometry, and biochemical assays. Additionally, the RNA immunoprecipitation (RIP) assay was used to examine the impact of METTL3/IGF2BP3 on the m6A modification of the SLC38A1 3'UTR. Both cervical cancer specimens and cells showed significantly increased expression of SLC38A1 and its expression correlated with an unfavorable prognosis. Knockdown of SLC38A1 inhibited cell viability and cell cycle progression, induced apoptosis, and suppressed tumor growth in vivo. Glutaminase-1 inhibitor CB-839 reversed the effects of SLC38A1 overexpression. METTL3 promoted m6A modification of SLC38A1 and enhanced its mRNA stability through IGF2BP3 recruitment. Moreover, METTL3 silencing inhibited cell viability, cell cycle progression, intracellular glutamine content, and induced apoptosis, but these effects were reversed by SLC38A1 overexpression. In conclusion, METTL3-mediated m6A methylation of SLC38A1 stimulates cervical cancer progression. SLC38A1 inhibition is a potential therapeutic strategy for cervical cancer.

Lhx2 promotes axon regeneration of adult retinal ganglion cells and rescues neurodegeneration in mouse models of glaucoma.

The axons of retinal ganglion cells (RGCs) form the optic nerve, transmitting visual information from the eye to the brain. Damage or loss of RGCs and their axons is the leading cause of visual functional defects in traumatic injury and degenerative diseases such as glaucoma. However, there are no effective clinical treatments for nerve damage in these neurodegenerative diseases. Here, we report that LIM homeodomain transcription factor Lhx2 promotes RGC survival and axon regeneration in multiple animal models mimicking glaucoma disease. Furthermore, following N-methyl-D-aspartate (NMDA)-induced excitotoxicity damage of RGCs, Lhx2 mitigates the loss of visual signal transduction. Mechanistic analysis revealed that overexpression of Lhx2 supports axon regeneration by systematically regulating the transcription of regeneration-related genes and inhibiting transcription of Semaphorin 3C (Sema3C). Collectively, our studies identify a critical role of Lhx2 in promoting RGC survival and axon regeneration, providing a promising neural repair strategy for glaucomatous neurodegeneration.

Improved therapeutic effects on vascular intimal hyperplasia by mesenchymal stem cells expressing MIR155HG that function as a ceRNA for microRNA-205.

Coronary artery bypass grafting (CABG) is an effective treatment for coronary heart disease, with vascular transplantation as the key procedure. Intimal hyperplasia (IH) gradually leads to vascular stenosis, seriously affecting the curative effect of CABG. Mesenchymal stem cells (MSCs) were used to alleviate IH, but the effect was not satisfactory. This work aimed to investigate whether lncRNA MIR155HG could improve the efficacy of MSCs in the treatment of IH and to elucidate the role of the competing endogenous RNA (ceRNA). The effect of MIR155HG on MSCs function was investigated, while the proteins involved were assessed. IH was detected by HE and Van Gieson staining. miRNAs as the target of lncRNA were selected by bioinformatics analysis. qRT-PCR and dual-luciferase reporter assay were performed to verify the binding sites of lncRNA-miRNA. The apoptosis, Elisa and tube formation assay revealed the effect of ceRNA on the endothelial protection of MIR155HG-MSCs. We observed that MIR155HG improved the effect of MSCs on IH by promoting viability and migration. MIR155HG worked as a sponge for miR-205. MIR155HG/miR-205 significantly improved the function of MSCs, avoiding apoptosis and inducing angiogenesis. The improved therapeutic effects of MSCs on IH might be due to the ceRNA role of MIR155HG/miR-205.

USP39 Promotes the Viability and Migration of Head and Neck Squamous Cell Carcinoma Cell by Regulating STAT1.

Objective: Ubiquitin-specific peptidase 39 (USP39) plays a carcinogenic role in many cancers, but little research has been conducted examining whether it is involved in head and neck squamous cell carcinoma (HNSCC). Therefore, this study explored the functional role of USP39 in HNSCC. Method: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify differentially expressed proteins (DEPs) between the HNSCC tumor and adjacent healthy tissues. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were used to assess the functional enrichment of DEPs. Immunohistochemistry was used to detect protein expression. The viability and migration of two HNSCC cell lines, namely CAL27 and SCC25, were detected using the cell counting kit-8 assay and a wound healing assay, respectively. Quantitative real-time PCR was used to detect the expression level of signal transducer and activator of transcription 1 (STAT1) mRNA. Results: LC-MS/MS results identified 590 DEPs between HNSCC and adjacent tissues collected from 4 patients. Through GO and KEGG pathway analyses, 34 different proteins were found to be enriched in the spliceosome pathway. The expression levels of USP39 and STAT1 were significantly higher in HNSCC tumor tissue than in adjacent healthy tissue as assessed by LC-MS/MS analysis, and the increased expression of USP39 and STAT1 protein was confirmed by immunohistochemistry in clinical samples collected from 7 additional patients with HNSCC. Knockdown of USP39 or STAT1 inhibited the viability and migration of CAL27 and SCC25 cells. In addition, USP39 knockdown inhibited the expression of STAT1 mRNA in these cells. Conclusion: Our findings indicated that USP39 knockdown may inhibit HNSCC viability and migration by suppressing STAT1 expression. The results of this study suggest that USP39 may be a potential new target for HNSCC clinical therapy or a new biomarker for HNSCC.

The lincRNA JUNI regulates the stress-dependent induction of c-Jun, cellular migration and survival through the modulation of the DUSP14-JNK axis.

Cancer cells employ adaptive mechanisms to survive various stressors, including genotoxic drugs. Understanding the factors promoting survival is crucial for developing effective treatments. In this study, we unveil a previously unexplored long non-coding RNA, JUNI (JUN-DT, LINC01135), which is upregulated by genotoxic drugs through the activation of stress-activated MAPKs, JNK, and p38 and consequently exerts positive control over the expression of its adjacent gene product c-Jun, a well-known oncoprotein, which transduces signals to multiple transcriptional outputs. JUNI regulates cellular migration and has a crucial role in conferring cellular resistance to chemotherapeutic drugs or UV radiation. Depletion of JUNI markedly increases the sensitivity of cultured cells and spheroids to chemotherapeutic agents. We identified 57 proteins interacting with JUNI. The activity of one of them the MAPK phosphatase and inhibitor, DUSP14, is counteracted by JUNI, thereby, facilitating efficient JNK phosphorylation and c-Jun induction when cells are exposed to UV radiation. The antagonistic interplay with DUSP14 contributes not only to c-Jun induction but also augments the survival of UV-exposed cells. In summary, we introduce JUNI as a novel stress-inducible regulator of c-Jun, positioning it as a potential target for enhancing the sensitivity of cancer cells to chemotherapy.

E2F transcription factors promote tumorigenicity in pancreatic ductal adenocarcinoma.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with limited treatment options, illustrating an urgent need to identify new drugable targets in PDACs. OBJECTIVE: Using the similarities between tumor development and normal embryonic development, which is accompanied by rapid cell expansion, we aimed to identify and characterize embryonic signaling pathways that were reinitiated during tumor formation and expansion. METHODS AND RESULTS: Here, we report that the transcription factors E2F1 and E2F8 are potential key regulators in PDAC. E2F1 and E2F8 RNA expression is mainly localized in proliferating cells in the developing pancreas and in malignant ductal cells in PDAC. Silencing of E2F1 and E2F8 in PANC-1 pancreatic tumor cells inhibited cell proliferation and impaired cell spreading and migration. Moreover, loss of E2F1 also affected cell viability and apoptosis with E2F expression in PDAC tissues correlating with expression of apoptosis and mitosis pathway genes, suggesting that E2F factors promote cell cycle regulation and tumorigenesis in PDAC cells. CONCLUSION: Our findings illustrate that E2F1 and E2F8 transcription factors are expressed in pancreatic progenitor and PDAC cells, where they contribute to tumor cell expansion by regulation of cell proliferation, viability, and cell migration making these genes attractive therapeutic targets and potential prognostic markers for pancreatic cancer.

Research of the unrecognised functions of miR-375 in prostate cancer cells.

Many cancers, including prostate cancer, have miRNAs with altered expression levels. These miRNAs play a pivotal role in regulating cancer initiation, invasion, and metastasis. miRNAs are an important component in cancer diagnosis and therapy and can play a key role as biomarkers or chemotherapeutic agents.  This investigation aimed to show the effects of miR-375 on PCa. In this project, target prediction tools and the KEGG pathway were performed to determine the potential targets of miR-375. Transfection was performed using miR-375 mimic and inhibitor. The actions of miRNAs on cell viability and migration were examined in PCa cells. In addition, qRT-PCR was executed to evaluate changes in gene expression in the PI3K-mTOR pathway. The analyses exposed that the upregulation of miR-375 repressed the viability at 48 h. While stimulation of miR-375 did not repress the migration, suppression of miR-375 reduced the migration at 24 and 48 hours. The predicted target TSC1 gene is not directly targeted by miR-375. Interestingly, in response to PIK3CA increase, mTOR expression was suppressed in all cells except LNCAP cells. In conclusion, miR-375 has anti-proliferative and cell migration inhibitory effects in prostate cancer. However, studies demonstrate that miR-375 may have tumor suppressor and oncogenic effects when considering cell molecular differences.

The role of hsa_circ_0042260/miR-4782-3p/LAPTM4A axis in gestational diabetes mellitus.

Gestational diabetes mellitus (GDM) is a common metabolic condition during pregnancy, posing risks to both mother and fetus. CircRNAs have emerged as important players in various diseases, including GDM. We aimed to investigate the role of newly discovered circRNA, hsa_circ_0042260, in GDM pathogenesis. Using GSE194119 dataset, hsa_circ_0042260 was identified and its expression in plasma, placenta, and HG-stimulated HK-2 cells was examined. Silencing hsa_circ_0042260 in HK-2 cells assessed its impact on cell viability, apoptosis, and inflammation. Bioinformatics analysis revealed downstream targets of hsa_circ_0042260, namely miR-4782-3p and LAPTM4A. The interaction between hsa_circ_0042260, miR-4782-3p, and LAPTM4A was validated through various assays. hsa_circ_0042260 was upregulated in plasma from GDM patients and HG-stimulated HK-2 cells. Silencing hsa_circ_0042260 improved cell viability, suppressed apoptosis and inflammation. Hsa_circ_0042260 interacted with miR-4782-3p, which exhibited low expression in GDM patient plasma and HG-stimulated cells. MiR-4782-3p targeted LAPTM4A, confirmed by additional assays. LAPTM4A expression increased in GDM patient plasma and HG-induced HK-2 cells following hsa_circ_0042260 knockdown or miR-4782-3p overexpression. In rescue assays, inhibition of miR-4782-3p or overexpression of LAPTM4A counteracted the effects of hsa_circ_0042260 downregulation on cell viability, apoptosis, and inflammation. In conclusion, the hsa_circ_0042260/miR-4782-3p/LAPTM4A axis plays a role in regulating GDM progression in HG-stimulated HK-2 cells.

Multiple genetic variants at the SLC30A8 locus affect local super-enhancer activity and influence pancreatic ß-cell survival and function.

Variants at the SLC30A8 locus are associated with type 2 diabetes (T2D) risk. The lead variant, rs13266634, encodes an amino acid change, Arg325Trp (R325W), at the C-terminus of the secretory granule-enriched zinc transporter, ZnT8. Although this protein-coding variant was previously thought to be the sole driver of T2D risk at this locus, recent studies have provided evidence for lowered expression of SLC30A8 mRNA in protective allele carriers. In the present study, we examined multiple variants that influence SLC30A8 allele-specific expression. Epigenomic mapping has previously identified an islet-selective enhancer cluster at the SLC30A8 locus, hosting multiple T2D risk and cASE associations, which is spatially associated with the SLC30A8 promoter and additional neighboring genes. Here, we show that deletion of variant-bearing enhancer regions using CRISPR-Cas9 in human-derived EndoC-ßH3 cells lowers the expression of SLC30A8 and several neighboring genes and improves glucose-stimulated insulin secretion. While downregulation of SLC30A8 had no effect on beta cell survival, loss of UTP23, RAD21, or MED30 markedly reduced cell viability. Although eQTL or cASE analyses in human islets did not support the association between these additional genes and diabetes risk, the transcriptional regulator JQ1 lowered the expression of multiple genes at the SLC30A8 locus and enhanced stimulated insulin secretion.

The tumor suppressor effect of miRNA 200-c-3p on A549 non-small cell lung cancer cell line is associated with down-regulation of programmed cell death ligand 1; an immune-check point mechanism.

MiRNA 200-c-3p has varying functions in different tumor types, whether tumor suppression or promotion. Comprehensive assessment of its function in non-small cell lung cancer (NSCLC) together with its effect on antitumor immune response have not been declared before. We aimed to explore the effect of replacement and suppression of miRNA 200-c-3p on non-small cell lung cancer and its impact on immune checkpoint function and subsequently antitumor immunity. MiRNA 200-c-3p mimic/inhibitor was transfected into the A549 cells. A 549 non-small cell lung cancer cells viability was done by trypan blue staining and 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flowcytometric analysis was done for apoptosis detection. Real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used to study its effect on relative gene expression and relative protein level of programmed cell death ligand 1 (PD-L1). Finally, co-culture with isolated and activated T cells was performed. Multiple comparisons were performed using one-way analysis of variance (ANOVA) followed by Tukey's multiple-comparison test. Decreased cell viability, increased apoptosis, reduced PD-L1 relative gene expression and its relative protein level, together with enhanced T cell cytotoxicity towards tumor cells were detected after miRNA 200-c-3p mimic transfection of A549 NSCLC cell line.  However, these results were reversed in miRNA 200-c-3p suppression. MiRNA 200-c-3p had a tumor suppressive effect in non-small cell lung cancer cells which might be through down regulation of PD-L1 relative gene expression, and it may be used as a new target to improve immune checkpoint dysfunction.

MiR-4319 targets tuftelin 1 to reduce malignancy of cervical cancer cells.

Cervical cancer (CC) is the most common malignant tumor of female reproductive system. MiR-4319 has been identified as an anti-oncogene in various cancers. In the present study, role of miR-4319 in CC was identified. Colony formation, flow cytometer, wound healing, and transwell assays were used to detect CC cell proliferation, apoptosis, migration, and invasion. The expression of miR-4319 was decreased in clinical CC tissues and CC cell lines. Upregulation of miR-4319 suppressed cell viability, proliferation, migration, and invasion, and induced cell apoptosis in CC cells. Moreover, tuftelin 1 (TUFT1) was verified as a direct target of miR-4319, as confirmed by dual-luciferase reporter assay. Additionally, TUFT1 expression was remarkably increased in clinical CC tissues and CC cell lines and was negatively associated with miR-4319 expression. Furthermore, overexpression of TUFT1 partially restored the effects of miR-4319 mimic on cell viability, proliferation, migration, invasion, and cell apoptosis in CC cells. To conclude, miR-4319 played an anti-cancer role in the occurrence and development of CC, which might be achieved by targeting TUFT1.

The Transcription Factor Zfp335 Promotes Differentiation and Survival of Effector Th1 Cells by Directly Regulating Lmna Expression.

Ag-specific effector CD4+ T cells play a crucial role in defending against exogenous pathogens. However, the mechanisms governing the differentiation and function of IFN-γ-producing effector CD4+ Th1 cells in immune responses remain largely unknown. In this study, we elucidated the pivotal role of zinc finger protein 335 (Zfp335) in regulating effector Th1 cell differentiation and survival during acute bacterial infection. Mice with Zfp335 knockout in OT-II cells exhibited impaired Ag-specific CD4+ T cell expansion accompanied by a significant reduction in resistance to Listeria infection. Furthermore, Zfp335 deficiency restricted the effector CD4+ Th1 cell population and compromised their survival upon Listeria challenge. The expression of T-bet and IFN-γ was accordingly decreased in Zfp335-deficient Th1 cells. Mechanistically, Zfp335 directly bound to the promoter region of the Lmna gene and regulated its expression. Overexpression of Lmna was able to rescue the survival and function of Zfp335-deficient effector Th1 cells. Therefore, our study provides novel insights into the mechanisms governing effector Th1 cell differentiation and survival during acute infection.

DNMT1-mediated epigenetic suppression of FBXO32 expression promoting cyclin dependent kinase 9 (CDK9) survival and esophageal cancer cell growth.

Esophageal cancer (EC) is a common and serious form of cancer, and while DNA methyltransferase-1 (DNMT1) promotes DNA methylation and carcinogenesis, the role of F-box protein 32 (FBXO32) in EC and its regulation by DNMT1-mediated methylation is still unclear. FBXO32 expression was examined in EC cells with high DNMT1 expression using GSE163735 dataset. RT-qPCR assessed FBXO32 expression in normal and EC cells, and impact of higher FBXO32 expression on cell proliferation, migration, and invasion was evaluated, along with EMT-related proteins. The xenograft model established by injecting EC cells transfected with FBXO32 was used to evaluate tumor growth, apoptosis, and tumor cells proliferation and metastasis. Chromatin immunoprecipitation (ChIP) assay was employed to study the interaction between DNMT1 and FBXO32. HitPredict, co-immunoprecipitation (Co-IP), and Glutathione-S-transferase (GST) pulldown assay analyzed the interaction between FBXO32 and cyclin dependent kinase 9 (CDK9). Finally, the ubiquitination assay identified CDK9 ubiquitination, and its half-life was measured using cycloheximide and confirmed through western blotting. DNMT1 negatively correlated with FBXO32 expression in esophageal cells. High FBXO32 expression was associated with better overall survival in patients. Knockdown of DNMT1 in EC cells increased FBXO32 expression and suppressed malignant phenotypes. FBXO32 repressed EC tumor growth and metastasis in mice. Enrichment of DNMT1 in FBXO32 promoter region led to increased DNA methylation and reduced transcription. Mechanistically, FBXO32 degraded CDK9 through promoting its ubiquitination.

An unappreciated cell survival-independent role for BAFF initiating chronic lymphocytic leukemia.

Background: Chronic Lymphocytic Leukemia (CLL) is characterized by the expansion of CD19+ CD5+ B cells but its origin remains debated. Mutated CLL may originate from post-germinal center B cells and unmutated CLL from CD5+ mature B cell precursors. Irrespective of precursor types, events initiating CLL remain unknown. The cytokines BAFF and APRIL each play a significant role in CLL cell survival and accumulation, but their involvement in disease initiation remains unclear. Methods: We generated novel CLL models lacking BAFF or APRIL. In vivo experiments were conducted to explore the impact of BAFF or APRIL loss on leukemia initiation, progression, and dissemination. Additionally, RNA-seq and quantitative real-time PCR were performed to unveil the transcriptomic signature influenced by BAFF in CLL. The direct role of BAFF in controlling the expression of tumor-promoting genes was further assessed in patient-derived primary CLL cells ex-vivo. Results: Our findings demonstrate a crucial role for BAFF, but not APRIL, in the initiation and dissemination of CLL cells. In the absence of BAFF or its receptor BAFF-R, the TCL1 transgene only increases CLL cell numbers in the peritoneal cavity, without dissemination into the periphery. While BAFF binding to BAFF-R is dispensable for peritoneal CLL cell survival, it is necessary to activate a tumor-promoting gene program, potentially linked to CLL initiation and progression. This direct role of BAFF in controlling the expression of tumor-promoting genes was confirmed in patient-derived primary CLL cells ex-vivo. Conclusions: Our study, involving both mouse and human CLL cells, suggests that BAFF might initiate CLL through mechanisms independent of cell survival. Combining current CLL therapies with BAFF inhibition could offer a dual benefit by reducing peripheral tumor burden and suppressing transformed CLL cell output.

Maintenance of proteostasis by Drosophila Rer1 is essential for competitive cell survival and Myc-driven overgrowth.

Defects in protein homeostasis can induce proteotoxic stress, affecting cellular fitness and, consequently, overall tissue health. In various growing tissues, cell competition based mechanisms facilitate detection and elimination of these compromised, often referred to as 'loser', cells by the healthier neighbors. The precise connection between proteotoxic stress and competitive cell survival remains largely elusive. Here, we reveal the function of an endoplasmic reticulum (ER) and Golgi localized protein Rer1 in the regulation of protein homeostasis in the developing Drosophila wing epithelium. Our results show that loss of Rer1 leads to proteotoxic stress and PERK-mediated phosphorylation of eukaryotic initiation factor 2α. Clonal analysis showed that rer1 mutant cells are identified as losers and eliminated through cell competition. Interestingly, we find that Rer1 levels are upregulated upon Myc-overexpression that causes overgrowth, albeit under high proteotoxic stress. Our results suggest that increased levels of Rer1 provide cytoprotection to Myc-overexpressing cells by alleviating the proteotoxic stress and thereby supporting Myc-driven overgrowth. In summary, these observations demonstrate that Rer1 acts as a novel regulator of proteostasis in Drosophila and reveal its role in competitive cell survival.

N-MYC regulates cell survival via eIF4G1 in inv(16) acute myeloid leukemia.

N-MYC (encoded by MYCN) is a critical regulator of hematopoietic stem cell function. While the role of N-MYC deregulation is well established in neuroblastoma, the importance of N-MYC deregulation in leukemogenesis remains elusive. Here, we demonstrate that N-MYC is overexpressed in acute myeloid leukemia (AML) cells with chromosome inversion inv(16) and contributes to the survival and maintenance of inv(16) leukemia. We identified a previously unknown MYCN enhancer, active in multiple AML subtypes, essential for MYCN mRNA levels and survival in inv(16) AML cells. We also identified eukaryotic translation initiation factor 4 gamma 1 (eIF4G1) as a key N-MYC target that sustains leukemic survival in inv(16) AML cells. The oncogenic role of eIF4G1 in AML has not been reported before. Our results reveal a mechanism whereby N-MYC drives a leukemic transcriptional program and provides a rationale for the therapeutic targeting of the N-MYC/eIF4G1 axis in myeloid leukemia.