Prognostic Signatures and Therapeutic Value Based on the Notch Pathway in Renal Clear Cell Carcinoma

Stem cell therapy for intervertebral disc degeneration: Clinical progress with exosomes and gene vectors

Intervertebral disc degeneration is a leading cause of lower back pain and is characterized by pathological processes such as nucleus pulposus cell apoptosis, extracellular matrix imbalance, and annulus fibrosus rupture. These pathological changes result in disc height loss and functional decline, potentially leading to disc herniation. This comprehensive review aimed to address the current challenges in intervertebral disc degeneration treatment by evaluating the regenerative potential of stem cell-based therapies, with a particular focus on emerging technologies such as exosomes and gene vector systems. Through mechanisms such as differentiation, paracrine effects, and immunomodulation, stem cells facilitate extracellular matrix repair and reduce nucleus pulposus cell apoptosis. Despite recent advancements, clinical applications are hindered by challenges such as hypoxic disc environments and immune rejection. By analyzing recent preclinical and clinical findings, this review provided insights into optimizing stem cell therapy to overcome these obstacles and highlighted future directions in the field.

BEX4 inhibits the progression of clear cell renal cell carcinoma by stabilizing SH2D4A, which is achieved by blocking SIRT2 activity

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignancies. Recently, the role of brain-expressed X-linked 4 (BEX4) in cancer progression has received increasing attention. This study aimed to investigate the function of BEX4 in ccRCC and to reveal the underlying mechanisms. We first confirmed that BEX4 was significantly downregulated in ccRCC by bioinformatics analysis and that patients with low BEX4 expression tended to have prolonged overall survival time. Subsequently, we confirmed that BEX4 inhibited ccRCC cell proliferation in vitro and tumorigenesis in vivo through a series of cell function assays and the establishment of a nude mouse xenograft model, respectively. Mechanistically, we found that BEX4 positively regulates the expression of Src homology 2 domain-containing 4A (SH2D4A), an inhibitor of the NOTCH pathway, which further promoted the tumor-suppressive effects of BEX4. In addition, our study confirmed that the promoting effect of BEX4 on SH2D4A was achieved by inhibiting the deacetylase sirtuin 2 (SIRT2) activity. On this basis, we found that there was a competition between acetylation and ubiquitination modifications at the K69 site of SH2DA4 and that BEX4-induced upregulation of acetylation at the k69 site stabilizes SH2D4A protein expression by inhibiting ubiquitination at the same site. In addition, dual-luciferase assays showed that the transcriptional activity of BEX4 was positively regulated by activation transcription factor 3 (ATF3). Our study suggests that BEX4 plays a role in inhibiting tumor progression in ccRCC and maybe a new diagnostic and therapeutic target for ccRCC patients.

Deubiquitinating enzyme OTUD4 stabilizes RBM47 to induce ATF3 transcription: a novel mechanism underlying the restrained malignant properties of ccRCC cells

Dysregulation of deubiquitination contributes to various diseases, including cancer, and aberrant expression of deubiquitinating enzymes is involved in carcinoma progression. As a member of the ovarian tumor (OTU) deubiquitinases, OTUD4 is considered a tumor suppressor in many kinds of malignancies. The biological characteristics and mechanisms of OTUD4 in clear cell renal cell carcinoma (ccRCC) remain unclear. The downregulation of OTUD4 in ccRCC was confirmed based on the TCGA database and a validation cohort of 30-paired ccRCC and para-carcinoma samples. Moreover, OTUD4 expression was detected by immunohistochemistry in 50 cases of ccRCC tissues, and patients with lower levels of OTUD4 showed larger tumor size (p = 0.015). TCGA data revealed that patients with high expression of OTUD4 had a longer overall survival rate. In vitro and in vivo studies revealed that downregulation of OTUD4 was essential for tumor cell growth and metastasis in ccRCC, and OTUD4 overexpression inhibited these malignant phenotypes. We further found that OTUD4 sensitized ccRCC cells to Erastin-induced ferroptosis, and ferrostain-1 inhibited OTUD4-induced ferroptotic cell death. Mechanistic studies indicated that OTUD4 functioned as an anti-proliferative and anti-metastasic factor through the regulation of RNA-binding protein 47 (RBM47)-mediated activating transcription factor 3 (ATF3). OTUD4 directly interacted with RBM47 and promoted its stability via deubiquitination events. RBM47 was critical in ccRCC progression by regulating ATF3 mRNA stability, thereby promoting ATF3-mediated ferroptosis. RBM47 interference abolished the suppressive role of OTUD4 overexpression in ccRCC. Our findings provide mechanistic insight into OTUD4 of ccRCC progression and indicate a novel critical pathway OTUD4/RBM47/ATF3 may serve as a potential therapeutic pathway for ccRCC.

Notch activation defines immune-suppressive subsets of ccRCCs with unfavorable benefits from immunotherapy over VEGFR/mTOR inhibitors

The evolutionarily conserved Notch pathway, involved in cancer stem cell capacity and cancer immunity, may predict the benefit from immune checkpoint inhibitors (ICIs) in clear cell renal cell carcinoma (ccRCC). In the TCGA dataset, mRNA expression of Notch pathway genes identified three clusters with different prognoses and molecular characteristics. Based on the differentially expressed Notch pathway genes between clusters, we constructed the Notch-score, correlated with Notch activation, angiogenesis, PI3K-AKT-mTOR activity, and sensitivities to VEGFR/mTOR inhibitors. A high Notch-score was linked with more "resting"/"anti-inflammatory" rather than "activated"/"pro-inflammatory" tumor-infiltrating immune cells, inactivated immune pathways, and scarce any benefits from ICI-based therapies over VEGFR/mTOR inhibitors in the JAVELIN Renal 101 (avelumab plus axitinib vs. sunitinib) and the CheckMate-009/010/025 trials (nivolumab vs. everolimus). For the Notch-activated ccRCCs, ICIs provide limited advantages and might not be strongly recommended, by which the cost-effectiveness of treatments in ccRCCs may be potentially improved.

Multi-omics pan-cancer study of cuproptosis core gene FDX1 and its role in kidney renal clear cell carcinoma

BACKGROUND

The mechanism of copper-induced cellular death was newly discovered and termed cuproptosis. Inducing cuproptosis in cancer cells is well anticipated for its curative potential in treating tumor diseases. However, ferredoxin 1 (FDX1), the core regulatory gene in cuproptosis, is rarely studied, and the regulation of FDX1 in tumor biology remains obscure. A comprehensive pan-cancer analysis of FDX1 is needed.

METHODS

Thirty-three types of tumors were included with paired normal tissues in The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) datasets. The interaction between transcription, protein, phosphorylation, and promoter methylation levels was analyzed. Survival, immune infiltration, single-cell FDX1 expression, FDX1-related tumor mutational burden (TMB), microsatellite instability (MSI), stemness, tumor immune dysfunction and exclusion (TIDE), and immunotherapy-related analyses were performed. FDX1 protein expression was assessed by kidney renal clear cell carcinoma (KIRC) tissue microarray immunohistochemistry. The function of FDX1 in KIRC was further explored by experiments in 786-O cell lines in vitro.

RESULTS

FDX1 is highly expressed in 15 tumor types and lowly expressed in 11 tumor types. The corresponding changes in protein expression, phosphorylation, and promoter methylation level of FDX1 have been described in several tumors. Survival analysis showed that FDX1 was related to favorable or poor overall survival in eight tumors and progression-free survival in nine tumors. Immune infiltration and single-cell analysis indicated the indispensable role of FDX1 expression in macrophages and monocytes. Multiple established immunotherapy cohorts suggested that FDX1 may be a potential predictor of treatment effects for tumor patients. Tissue microarray analysis showed decreased FDX1 expression in KIRC patients' tumor tissues. Knockdown of FDX1 resulted in the downregulation of cuproptosis in kidney renal clear tumor cells. Mechanistically, the FDX1-associated gene expression signature in KIRC is related to the enrichment of genes involved in the tricarboxylic acid (TCA) cycle, NOTCH pathway, etc. Several NOTCH pathway genes were differentially expressed in the high- and low-FDX1 groups in KIRC.

CONCLUSION

Our analysis showed that the central regulatory gene of cuproptosis, FDX1, has differential expression and modification levels in various tumors, which is associated with cellular function, immune modulation, and disease prognosis. Thus, FDX1-dependent cuproptosis may serve as a brand-new target in future therapeutic approaches against tumors.

Comprehensive characterization of extracellular matrix-related genes in PAAD identified a novel prognostic panel related to clinical outcomes and immune microenvironment: A silico analysis with in vivo and vitro validation

The extracellular matrix (ECM) is a vital component of the tumor microenvironment, which interplays with stromal and tumor cells to stimulate the capacity of cancer cells to proliferate, migrate, invade, and undergo angiogenesis. Nevertheless, the crucial functions of ECM-related genes (ECMGs) in pancreatic adenocarcinoma (PAAD) have not been systematically evaluated. Hence, a comprehensive evaluation of the ECMGs is required in pan-cancer, especially in PAAD. First, a pan-cancer overview of ECMGs was explored through the integration of expression profiles, prognostic values, mutation information, methylation levels, and pathway-regulation relationships. Seven ECMGs (i.e. LAMB3, LAMA3, ITGB6, ITGB4, ITGA2, LAMC2, and COL11A1) were identified to be hub genes of PAAD, which were obviously up-regulated in PAAD and considerably linked to tumor stage as well as prognosis. Subsequently, patients with PAAD were divided into 3 clusters premised on ECMG expression and ECM scores. Cluster 2 was the subtype with the best prognosis accompanied by the lowest ECM scores, further verifying ECM’s significant contribution to the pathophysiological processes of PAAD. Significant differences were observed for oncogene and tumor suppressor gene expression, immune microenvironment, and chemotherapy sensitivity across three ECM subtypes. After applying a variety of bioinformatics methods, a novel and robust ECM-associated mRNA-lncRNA-based prognostic panel (ECM-APP) was developed and validated for accurately predicting clinical outcomes of patients with PAAD. Patients with PAAD were randomly categorized into the train, internal validation, and external validation cohorts; meanwhile, each patient was allocated into high-risk (unfavorable prognosis) and low-risk (favorable prognosis) populations premised on the expression traits of ECM-related mRNAs and lncRNAs. The discrepancy in the tumor mutation burden and immune microenvironment might be responsible for the difference in prognoses across the high-risk and low-risk populations. Overall, our findings identified and validated seven ECMGs remarkably linked to the onset and progression of PAAD. ECM-based molecular classification and prognostic panel aid in the prognostic assessment and personalized intervention of patients with PAAD.

Identification and validation of a prognostic risk-scoring model based on sphingolipid metabolism-associated cluster in colon adenocarcinoma

Colon adenocarcinoma (COAD) is the primary factor responsible for cancer-related mortalities in western countries, and its development and progression are affected by altered sphingolipid metabolism. The current study aimed at investigating the effects of sphingolipid metabolism-related (SLP) genes on multiple human cancers, especially on COAD. We obtained 1287 SLP genes from the GeneCard and MsigDb databases along with the public transcriptome data and the related clinical information. The univariate Cox regression analysis suggested that 26 SLP genes were substantially related to the prognosis of COAD, and a majority of SLP genes served as the risk genes for the tumor, insinuating a potential pathogenic effect of SLP in COAD development. Pan-cancer characterization of SLP genes summarized their expression traits, mutation traits, and methylation levels. Subsequently, we focused on the thorough research of COAD. With the help of unsupervised clustering, 1008 COAD patients were successfully divided into two distinct subtypes (C1 and C2). C1 subtype is characterized by a poor prognosis, activation of SLP pathways, high expression of SLP genes, disordered carcinogenic pathways, and immune microenvironment. Based on the clusters of SLP, we developed and validated a novel prognostic model, consisting of ANO1, C2CD4A, EEF1A2, GRP, HEYL, IGF1, LAMA2, LSAMP, RBP1, and TCEAL2, to quantitatively evaluate the clinical outcomes of COAD. The Kaplain-Meier survival curves and ROC curves highlighted the accuracy of our SLP model in both internal and external cohorts. Compared to normal colon tissues, expression of C2CD4A was detected to be significantly higher in COAD; whereas, expression levels of EEF1A2, IGF1, and TCEAL2 were detected to be significantly lower in COAD. Overall, our research emphasized the pathogenic role of SLP in COAD and found that targeting SLP might help improve the clinical outcomes of COAD. The risk model based on SLP metabolism provided a new horizon for prognosis assessment and customized patient intervention.