Molecular Oncology最新文献

Glioblastoma is the most common primary malignant brain tumor in adults, with a median survival of just over 1 year. The failure of available treatments to achieve remission in patients with glioblastoma (GBM) has been attributed to the presence of cancer stem cells (CSCs), which are thought to play a central role in tumor development and progression and serve as a treatment-resistant cell repository capable of driving tumor recurrence. In fact, the property of "stemness" itself may be responsible for treatment resistance. In this study, we identify a novel long noncoding RNA (lncRNA), cancer stem cell-associated distal enhancer of SOX2 (CASCADES), that functions as an epigenetic regulator in glioma CSCs (GSCs). CASCADES is expressed in isocitrate dehydrogenase (IDH)-wild-type GBM and is significantly enriched in GSCs. Knockdown of CASCADES in GSCs results in differentiation towards a neuronal lineage in a cell- and cancer-specific manner. Bioinformatics analysis reveals that CASCADES functions as a super-enhancer-associated lncRNA epigenetic regulator of SOX2. Our findings identify CASCADES as a critical regulator of stemness in GSCs that represents a novel epigenetic and therapeutic target for disrupting the CSC compartment in glioblastoma.

High-risk neuroblastomas, often associated with MYCN protooncogene amplification, are addicted to polyamines, small polycations vital for cellular functioning. We have previously shown that neuroblastoma cells increase polyamine uptake when exposed to the polyamine biosynthesis inhibitor difluoromethylornithine (DFMO), and this mechanism is thought to limit the efficacy of the drug in clinical trials. This finding resulted in the clinical development of polyamine transport inhibitors, including AMXT 1501, which is presently under clinical investigation in combination with DFMO. However, the mechanisms and transporters involved in DFMO-induced polyamine uptake are unknown. Here, we report that knockdown of ATPase 13A3 (ATP13A3), a member of the P5B-ATPase polyamine transporter family, limited basal and DFMO-induced polyamine uptake, attenuated MYCN-amplified and non-MYCN-amplified neuroblastoma cell growth, and potentiated the inhibitory effects of DFMO. Conversely, overexpression of ATP13A3 in neuroblastoma cells increased polyamine uptake, which was inhibited by AMXT 1501, highlighting ATP13A3 as a key target of the drug. An association between high ATP13A3 expression and poor survival in neuroblastoma further supports a role of this transporter in neuroblastoma progression. Thus, this study identified ATP13A3 as a critical regulator of basal and DFMO-induced polyamine uptake and a novel therapeutic target for neuroblastoma.

Rejuvenation of elementary immune system components has emerged as a promising strategy to deal with increased susceptibility to infections, cancers, autoimmune disorders, and low efficacy to vaccines, frequently accompanying aging. In this context, the thymus has gained significant attention. A recent study by Santamaria et al. reveals that the receptor activator of nuclear factor-κB (RANK)-RANK ligand (RANKL) axis is altered during age related thymic involution, compromising immune responses. Based on their findings, authors propose exogenous RANKL administration as a therapeutic strategy to reinvigorate thymic function and improve T-cell immunity during aging.

Targeting the heterodimer MDM2/MDM4 is a novel and effective route for the reactivation of wild-type p53 in human tumors with reduced toxicity in nontransformed cells. To improve the therapeutic potential of peptides that interfere with MDM4 binding to MDM2, we demonstrated the tumor-suppressive activity of a short peptide (Pep3S), which is composed of the last five amino acids of the MDM4 protein. Compared to longer peptides (previously identified), Pep3S binds MDM2 with high affinity, increases p53-dependent cell death in 2D and 3D colorectal cancer models, and is more efficacious in suppressing xenograft tumor growth. Furthermore, its encapsulation in poly (lactic-co-glycolic acid) (PLGA) nanoparticles potentiated and prolonged its activity. A p53-specific target gene array revealed an uncommon p53 signature, with Pep3S leading to p53-mediated repression of a subset of p53 targets. Comparative analysis indicated that this repression is driven by p53-mediated activation of miR-34a, which is functional in Pep3S-induced cell death. Of note, unlike other p53-reactivating molecules, Pep3S led to significant downregulation of the cell cycle inhibitor CDKN1A/p21, one of the best-characterized p53-targets. Genetic manipulation of MDM4 demonstrated the requirement of the dissociated protein for p21 downregulation, whereas the miR-34a signature was not altered. At odds with Nutlin-3a, the proliferation status of nontumor muscle and lymphoblastoid cells was not altered by Pep3S. These data indicate that targeting the MDM2/MDM4 interaction region provides a different route for wild-type p53 reactivation in human tumors, potentially reducing toxicity to proliferating nontumor tissue. The development of a PLGA/Pep3S formulation represents a promising approach for therapeutic purposes.

Hepatocellular carcinoma (HCC), the sixth most prevalent cancer globally, is characterized by high recurrence rates and poor prognosis. Investigating the heterogeneity of relapsed HCC and identifying key therapeutic targets may facilitate the design of effective anticancer therapies. In this study, integrative analysis of single-cell RNA sequencing data of primary and early-relapsed HCC revealed increased proportions of infiltrating CD8⁺ T cells along with malignant cells and a decrease in CD4⁺ T cells in relapsed HCC. Cellular interaction and immunohistochemical analysis proposed MIF-(CD74 + CXCR4) signaling pathway as a key mechanism by which malignant cells influence immune cells within the tumor microenvironment. Notably, primary malignant cells showed greater differentiation and proliferation potential, whereas relapsed cells exhibited enhanced epithelial-mesenchymal transition and inflammation, along with upregulated glycogen synthesis and metabolism-related gene expression. Using machine learning techniques on bulk RNA-seq data, we developed a relapsed tumor cell-related risk score (RTRS) that independently predicts overall and recurrence-free survival time with higher accuracy compared with conventional clinical variables. Prognostic biomarkers and potential therapeutic targets were validated via RT-qPCR using mouse implantation models. This comprehensive investigation elucidates the heterogeneity of relapsed HCC and constructs a novel postoperative recurrence prognostic model, paving the way for targeted therapies and improved patient outcomes.

Colorectal cancer (CRC) is widely recognized for its high prevalence and significant mortality rates, and purine metabolism has been serving as a potential therapeutic target. However, purine metabolism has not yet been validated as a prognostic marker through immunohistochemical analysis. In this study, we utilized a combination of bulk transcriptome analysis, immunohistochemistry (IHC), and single-cell RNA sequencing (scRNA-seq) to assess the clinical relevance of purine metabolism in CRC. Low expression levels of five purine metabolism-related genes-ADSL, APRT, ADCY3, NME3, and NME6-were associated with worse prognosis in CRC patient subgroups, including wild-type TP53, mutant TP53, and microsatellite-stable phenotypes. IHC-based validation showed that NME3 expression was an independent prognostic factor, whereas ADSL and NME6 expressions were associated with clinical variables in prediction of prognosis. Notably, NME3 expression predicted a high risk in patients with early-stage CRC, while ADSL and NME6 expressions were predictive in late-stage CRC. scRNA-seq analysis showed that four genes, excluding NME6, had low expression levels in epithelial cells at the late-stage CRC. Despite the reversible nature of purine metabolism reactions, we demonstrated a consistent directional expression of these five prognostic purine metabolism-related proteins in CRC tissues. We suggest that alterations in purine metabolism could serve as a clinically useful prognostic marker in CRC.

Glioblastoma (GBM) is the most aggressive and lethal type of glioma, characterized by aberrant expression of noncoding RNAs including circular RNAs (circRNAs). CircRNAs may impact cellular processes by interacting with other molecules-like RNA-binding proteins (RBPs). The diagnostic value of circRNA and circRNA/RBP complexes is still largely unknown. To explore circRNA and RBP transcript expression in GBM, we performed and further analyzed RNA-seq data from GBM patients' primary and recurrent tumor samples. We identified circRNAs differentially expressed in primary tumors, the circRNA progression markers in recurrent GBM samples, and the expression profile of RBP genes. Furthermore, we demonstrated the clinical potential of circRNAs and RBPs in GBM and proposed them as stratification markers in de novo assembled tumor subtypes. Additionally, we experimentally validated the subcellular localization of select circRNAs and their interactions with FUS. Subsequently, we showed that circARID1A may play a role in promoting GBM cell proliferation. Overall, we described circRNA-RBP interactions that could play a regulatory role in gliomagenesis and GBM progression and provided a list of molecular players in GBM for further extensive studies.

Cholesterol (CHOL) homeostasis is significantly modulated in prostate cancer (PCa) suggesting an active role in PCa development and progression. Several studies indicate a strong correlation between elevated CHOL levels and increased PCa risk and severity. Inhibition of CHOL biosynthesis at different steps, including lanosterol synthase (LSS), has shown significant efficacy against both hormone-dependent and castration-resistant PCa. Earlier, we reported proteasomal degradation of androgen receptor (AR)/AR-Vs and Mnk1/2 as the primary mechanisms of action of VNPP433-3β in inhibiting PCa cell proliferation and tumor growth. Through thermal proteome profiling, comparative proteomics and cellular thermal shift assay, we identified VNPP433-3β's ancillary effect of lowering CHOL by binding to LSS and lanosterol 14-alpha demethylase, potentially inhibiting CHOL biosynthesis in PCa cells and tumors. Additionally, in conjunction with our previously reported transcriptome analysis, proteomics reveals that VNPP433-3β modulated upstream regulators and pathways critical for PCa stem cell maintenance and recurrence. The inhibition of CHOL biosynthesis by VNPP433-3β reinforces its multifaceted effects in PCa across all stages, highlighting its potential as a single-agent therapy. Achieving reduced CHOL levels aligns with better treatment outcomes, further substantiating VNPP433-3β's therapeutic potential.

Oncogene-induced replication stress (RS) is a vulnerability of cancer cells that forces reliance on the intra-S-phase checkpoint to ensure faithful genome duplication. Inhibitors of the intra-S-phase checkpoint kinases ATR and CHK1 have been developed, but resistance to these drugs remains problematic. Understanding drug tolerance mechanisms is impeded by analysis of bulk samples, which neglect tumor heterogeneity and often fail to accurately interpret cell cycle-mediated resistance. Here, by combining intracellular immunostaining and single-cell RNA-sequencing, we characterized the transcriptomes of oncogenic RAS-expressing cells with variable levels of RS when challenged with a CHK1 inhibitor combined with gemcitabine. We identified 37 genes differentially expressed between tolerant and sensitive cells, including several FOXM1 targets. While complete knockdown of FOXM1 impeded cell proliferation, partial knockdown protected cells against DNA damage, and improved recovery from drug-induced RS. Remarkably, knockdown of individual FOXM1 target genes UBE2C and MKI67 also mitigated DNA damage, uncovering unanticipated roles for these in the replication stress response. Our results suggest that low levels of FOXM1-dependent gene expression during S and G2 phase protects cells against excessive DNA damage during drug-induced replication stress.

Chondrosarcomas are common bone sarcomas frequently resistant to radiation and chemotherapy, with high recurrence rates, development of metastatic disease, and death. Fibrosarcomas are soft tissue sarcomas associated with poor outcomes. Translocase of outer mitochondrial membrane receptor 20 (TOMM20) is a mitochondrial receptor protein associated with cancer aggressiveness in many cancer subtypes, but the mechanisms remain poorly understood. Here, we studied the effects of TOMM20 overexpression and downregulation on the redox state, mitochondrial oxidative phosphorylation (OXPHOS), and tumor growth using fibrosarcoma and chondrosarcoma models. TOMM20 overexpression increased OXPHOS, NADH, and NADPH with reduced cellular reactive oxygen species (ROS). TOMM20 induced resistance to apoptosis, including with BCL-2 and OXPHOS complex IV inhibitors, but with increased sensitivity to an OXPHOS complex I inhibitor. Also, TOMM20 induced cell growth and migration in vitro and promoted tumor growth in vivo. Conversely, knocking down TOMM20 using CRISPR-Cas9 reduced cancer aggressiveness in vivo in both chondrosarcoma and fibrosarcoma mouse models. In conclusion, TOMM20 is a driver of cancer aggressiveness by OXPHOS, apoptosis resistance, and the maintenance of a reduced state.