Oncogenesis最新文献

Cancer cells exploit epigenetic modifications and post-transcriptional regulations to form oncogenic gene expression networks. However, how these machineries collaboratively orchestrate malignancy remains elusive. One of aberrant epigenetic pathways in cancer is Polycomb repressive complex 1 (PRC)-mediated H2AK119 monoubiquitination (H2AK119ub1) with subsequent silencing of tumor suppressor genes. Despite previous efforts, the biological and clinical significance of PRC1 remains unclear in neuroblastoma (NB), an aggressive sympathoadrenal solid tumor in children. In this study, we demonstrated that knockdown of RING1A, one of the E3 ubiquitin ligases of PRC1, reduced cell viability and enrichment of H2AK119ub1 in NB cells. Transcriptional profiling revealed RING1A-specific targets, whose lower expression was associated with poor outcomes in NB patients. Among these genes, BTG2, a component of the CCR4-NOT polyA deadenylase complex, harbored a hypomethylated CpG island occupied by H2AK119ub1 and accessory proteins of noncanonical PRC1.1 (ncPRC1.1). Biological experiments uncovered that BTG2 suppressed NB cell growth in vitro and inhibited tumor formation in vivo. Moreover, BTG2 perturbed cell cycle progression and selectively destabilized the mRNAs of the cyclin genes CCNA2, CCNB1, and CCNB2. In NB patient cohorts, lower expression of BTG2 was associated with poor outcomes and inversely correlated with those cyclin gene expression. Collectively, we have uncovered a crosstalk between epigenetic modifications and post-transcriptional regulations, in which ncPRC1.1-mediated silencing of BTG2 retains cyclin gene expression and cell proliferation in NB. This study provides new insights into how epigenetic pathways contribute to NB malignancy.

Cancer cells infiltrating surrounding tissue frequently undergo partial epithelial-mesenchymal transitions (pEMT) and employ a collective mode of invasion. How these phenotypic traits are regulated and interconnected remains underexplored. Here, we used intestinal organoids with colorectal cancer (CRC) driver mutations as model system to investigate the mechanistic basis of TGF-β1-induced pEMT and collective invasion. By scRNA-seq we identified multiple cell subpopulations representing a broad pEMT spectrum, where the most advanced pEMT state correlated with the transcriptional profiles of leader cells in collective invasion and a poor prognosis mesenchymal subtype of human CRC. Bioinformatic analyses pinpointed Sox11 as a transcription factor gene whose expression peaked in the potential leader/pEMT^high cells. Immunofluorescence staining confirmed Sox11 expression in cells at the invasive front of TGF-β1-treated organoids. Loss-of-function and overexpression experiments showed that Sox11 is necessary, albeit not sufficient, for TGF-β1-induced pEMT and collective invasion. In human CRC samples, elevated SOX11 expression was associated with advanced tumor stages and worse prognosis. Unexpectedly, aside from orchestrating the organoid response to TGF-β1, Sox11 controlled expression of genes related to normal gut function and tumor suppression. Apparently, Sox11 is embedded in several distinct gene regulatory circuits, contributing to intestinal tissue homeostasis, tumor suppression, and TGF-β-mediated cancer cell invasion.

Nasopharyngeal carcinoma (NPC) is a special histological and ethical type of head and neck cancer with unsatisfactory clinical outcome. Thus, exploring effective molecular targets is critical for NPC treatment. We observed increased expression levels of synaptotagmin-7 (SYT7) in NPC tissues, which correlated with unfavorable prognoses. Furthermore, knockdown of SYT7 in NPC cells suppressed proliferation and migration rates, and enhanced apoptosis. In contrast, overexpression of SYT7 accelerated NPC tumor growth. Using whole-genome gene arrays and immunoprecipitation-mass spectrometry assays, aldehyde dehydrogenase 1 family member A3 (ALDH1A3), a regulator of glycolytic metabolism, was identified as a critical downstream target of SYT7. Mechanistically, SYT7 binds and promotes ALDH1A3 deubiquitination, resulting in decreased ALDH1A3 degradation. Notably, we also observed an increased expression of ALDH1A3 in NPC. More importantly, the knockdown of ALDH1A3 resulted in suppressed proliferation, migration, glycolysis, and promoted apoptosis, all of which could be restored by the overexpression of SYT7 in NPC cells. Taken together, we found that SYT7 increases ALDH1A3-mediated STAT3 activation and glycolysis, contributing to NPC progression, which provides a possible molecular mechanism for the development of targeted therapeutics interventions.

Recent studies have demonstrated that PLEKHA4 promotes tumor growth in some cancers, such as small-cell lung cancer, melanoma, and hepatic carcinomas; however, the underlying mechanism in glioblastoma remains ambiguous. Bioinformatic was used to analysis PLEKHA4 expression. In vitro and in vivo experiments were conducted to detect the effect of PLEKHA4 on glioblastoma cell glycolytic reprogramming and progression. GSEA was used to analyze the signal pathways related to PLEKHA4. Pharmacological methods further validated the role of activation pathways. We evaluated the effects of PLEKHA4 knockdown combined with temozolomide (TMZ) on glioblastoma cell proliferation and apoptosis in vitro and in vivo. We observed an overexpression of PLEKHA4 in GBM cell lines, resulting in enhanced cell proliferation, inhibited apoptosis, and promoted glycolysis. Mechanistically, our study demonstrated that PLEKHA4 mediates cell proliferation, apoptosis, and glycolysis via the STAT3/SOCS1 signaling pathway. Additionally, HOXD9 was predicted using Jasper, which is a transcription factor that binds to the PLEKHA4 promoter region. Knocking down PLEKHA4 combined with TMZ inhibited cell proliferation and promoted cell apoptosis in vitro and in vivo. Our results indicated that HOXD9-medicated PLEKHA4 regulates glioblastoma cell proliferation and glycolysis via activation of the STAT3/SOCS1 pathway.

Aberrant Receptor Tyrosine Kinase (RTK) signaling allows cancer cells to modulate survival, proliferation, and death, leading to tumorigenesis and chemoresistance. In leukemia, the RTK FMS-Related Tyrosine Kinase 4 (FLT4) (also known as VEGFR3, Vascular Endothelial Growth Factor Receptor- 3) is deregulated and correlates with cancer progression. However, the underlying consequences of its deregulation remain to be determined. Moreover, chemotherapy treatment requires that cancer cells retain a wild-type p53 to respond to DNA damage by tumor-suppressing activities, i.e. apoptosis. p53 activity is predominantly limited by its two major negative regulators, MDM2 and MDMX, which inactivate p53 by promoting its degradation and/or cytoplasmic localization. In this study, we have shown that activation of FLT4 by either overexpression or binding of its ligand, VEGFC, increases MDM2/MDMX stability, inactivates p53, and leads to resistance to DNA-damaging therapies. Moreover, we found that MDMX Ser-314 phosphorylation, a consensus sequence of CDK4/6, increases MDMX stability, which subsequently affects MDM2 and p53 degradation and could be reversed by the CDK4/6 inhibitor Palbociclib. More importantly, leukemic cells treated with Palbociclib were more susceptible to DNA-damaging induction of apoptosis and had reduced cell proliferation. Leukemic cells overexpressing FLT4 displayed accelerated proliferation when injected into NOD-SCID mice as compared to wild-type cells. Altogether, our research proposes an innovative way to reactivate p53 in leukemia through the pharmacological inhibition of FLT4 signaling, which could serve as a potential treatment option. Schematic representation of FLT4-mediated MDM2/MDMX complex stabilization and suppression of p53 activity. VEGFC triggers FLT4 activation, leading to CDK4/6 activation, which phosphorylates MDMX on Ser-314. As a result, MDMX levels increase and bind to MDM2, stabilizing the MDM2/MDMX complex. This complex binds to p53, facilitating its suppression by reducing its transcriptional activity or enhancing its export to the cytoplasm for proteasomal degradation. Consequently, p53 inactivation promotes their survival, proliferation, and resistance to chemotherapy-induced apoptosis. The figure was created in BioRender.com.

The oncoprotein MYCN drives malignancy in various cancer types, including neuroblastoma (NB). However, our understanding of the mechanisms underlying its transcriptional activity and oncogenic function, as well as effective strategies to target it, remains limited. We discovered that MYCN interacts with the transcriptional coactivator KAT2A, and this interaction significantly contributes to MYCN's activity in NB. Our genome-wide analyses indicate MYCN recruits KAT2A to bind to DNA, thereby transcriptionally regulating genes associated with ribosome biogenesis and RNA processing. Moreover, we identified that MYCN directly activates KAT2A transcription, while KAT2A acetylates MYCN, increasing MYCN protein stability. Consequently, MYCN and KAT2A establish a feedforward loop that effectively regulates global gene expression, governing the malignant NB phenotype. Treatment of NB cells with a KAT2A Proteolysis Targeting Chimera (PROTAC) degrader reduces MYCN protein levels, antagonizes MYCN-mediated gene transcription regulation and suppresses cell proliferation. This study highlights the potential of transcriptional cofactors as viable targets for developing anti-MYCN therapies.

Follicular thyroid carcinoma (FTC) is a common endocrine malignancy characterized by a higher propensity for invasion and metastasis compared to papillary thyroid carcinoma (PTC). Ephrin type A receptor 5 (EPHA5) is a crucial receptor tyrosine kinase involved in orchestrating diverse physiological processes, including apoptosis and proliferation. However, the mechanism of EPHA5 in FTC remains unclear. This study identified significant overexpression of EPHA5 in FTC. In vitro experiments showed that increased expression of EPHA5 promotes proliferation and inhibits apoptosis in FTC. Furthermore, EPHA5 activates the STAT3 signaling pathway. To explore the interaction between EPHA5 and the STAT3 signaling pathway, we used SH-4-54 (a STAT3-specific inhibitor). Interestingly, the influence of EPHA5 on proliferation and apoptosis was reduced upon combination with SH-4-54. In summary, this study unveils the involvement of the EPHA5-STAT3 signaling pathway in FTC and implies that the function of EPHA5 in FTC may partly depend on the STAT3 signaling pathway.

Fructose-1,6-bisphosphatase 1 (FBP1), a rate-limiting enzyme in gluconeogenesis, is important for cancer progression. The post-translational regulation of FBP1 in hypoxic environments is still unclear. Here, we report that FBP1 is down-regulated, and a low expression level of FBP1 predicts a poor prognosis in pancreatic cancer. A hypoxic environment makes FBP1 more prone to degradation, and this effect can be reversed by inhibiting global O-GlcNAcylation signalling. O-linked N-acetylglucosamine transferase (OGT) interacts with FBP1 and induces its O-GlcNAcylation at serine 47 residue (FBP1-S47) to modulate its protein function in pancreatic cancer cells. O-GlcNAcylation of FBP1-S47 promotes FBP1 degradation and also influences the expression of canonical HIF-1α target genes involved in glucose metabolism, resulting in an increase in glucose uptake and lactate secretion in pancreatic cancer cells. In addition, O-GlcNAcylation of FBP1-S47 facilitates FBP1 K48-linked polyubiquitination at lysine 51 residue (FBP1-K51), in which GlcNAc moiety can serve as a prerequisite for an FBP1 ubiquitin ligase. FBP1 (K51) K48-linked polyubiquitination mediated protein degradation can also promote cancer progression, similarly to the O-GlcNAcylation of FBP1-S47. Our data uncover a mechanism whereby FBP1 can be regulated by a protein O-GlcNAcylation-polyubiquitination axis, paving the way to cancer cell metabolic reprogramming.

MicroRNAs (miRNAs) are important regulators of gene expression whose dysregulation is widely linked to tumourigenesis, tumour progression and Epithelial-Mesenchymal Transition (EMT), a developmental process that promotes metastasis when inappropriately activated. However, controversy has emerged regarding how many functional miRNAs are encoded in the genome, and to what extent non-regulatory products of RNA degradation have been mis-identified as miRNAs. Central to miRNA function is their capacity to associate with an Argonaute (AGO) protein and form an RNA-Induced Silencing Complex (RISC), which mediates target mRNA suppression. We report that numerous "miRNAs" previously reported in EMT and cancer contexts, are not incorporated into RISC and are not capable of endogenously silencing target genes, despite the fact that hundreds of publications in the cancer field describe their roles. Apparent function can be driven through the expression of artificial miRNA mimics which is not necessarily reflective of any endogenous gene regulatory function. We present biochemical and bioinformatic criteria that can be used to distinguish functional miRNAs from mistakenly annotated RNA fragments.

Bone-marrow mesenchymal stem cells (BM-MSCs) rely on glycolysis, yet their trafficked mitochondria benefit recipient cells’ bioenergetics in regenerative and cancerous settings, most relevant to BM-resident multiple myeloma (MM) cells. Fission/fusion dynamics regulate mitochondria function. Proteomics demonstrates excessive mitochondrial processes in BM-MSCs from MM patients compared to normal donors (ND). Thus, we aimed to characterize BM-MSCs (ND, MM) mitochondrial fitness, bioenergetics and dynamics with a focus on therapeutics. MM-MSCs displayed compromised mitochondria evidenced by decreased mitochondrial membrane potential (ΔΨm) and elevated proton leak. This was accompanied by stimulation of stress-coping mechanisms: spare respiratory capacity (SRC), mitochondrial fusion and UPR^mt. Interfering with BM-MSCs mitochondrial dynamics equilibrium demonstrated their significance to bioenergetics and fitness according to the source. While ND-MSCs depended on fission, reducing MM-MSCs fusion attenuated glycolysis, OXPHOS and mtROS. Interestingly, optimization of mtROS levels is central to ΔΨm preservation in MM-MSCs only. MM-MSCs also demonstrated STAT3 activation, which regulates their OXPHOS and SRC. Targeting MM-MSC’ SRC with Venetoclax diminished their pro-MM support and sensitized co-cultured MM cells to Bortezomib. Overall, MM-MSCs distinct mitochondrial bioenergetics are integral to their robustness. Repurposing Venetoclax as anti-SRC treatment in combination with conventional anti-MM drugs presents a potential selective way to target MM-MSCs conferred drug resistance.