Connexin32 activates necroptosis through Src-mediated inhibition of caspase 8 in hepatocellular carcinoma

Ferroptosis, pyroptosis and necroptosis in hepatocellular carcinoma immunotherapy: Mechanisms and immunologic landscape (Review)

Hepatocellular carcinoma (HCC), one of the leading causes of cancer‑related mortality worldwide, is challenging to identify in its early stages and prone to metastasis, and the prognosis of patients with this disease is poor. Treatment options for HCC are limited, with even radical treatments being associated with a risk of recurrence or transformation in the short term. Furthermore, the multi‑tyrosine kinase inhibitors approved for first‑line therapy have marked drawbacks, including drug resistance and side effects. The rise and breakthrough of immune checkpoint inhibitors (ICIs) have provided a novel direction for HCC immunotherapy but these have the drawback of low response rates. Since avoiding apoptosis is a universal feature of cancer, the induction of non‑apoptotic regulatory cell death (NARCD) is a novel strategy for HCC immunotherapy. At present, NARCD pathways, including ferroptosis, pyroptosis and necroptosis, are novel potential forms of immunogenic cell death, which have synergistic effects with antitumor immunity, transforming immune 'cold' tumors into immune 'hot' tumors and exerting antitumor effects. Therefore, these pathways may be targeted as a novel treatment strategy for HCC. In the present review, the roles of ferroptosis, pyroptosis and necroptosis in antitumor immunity in HCC are discussed, and the relevant targets and signaling pathways, and the current status of combined therapy with ICIs are summarized. The prospects of targeting ferroptosis, pyroptosis and necroptosis in HCC immunotherapy are also considered.

Construction of an Immunogenic Cell Death-Related Gene Signature and Genetic Subtypes for Predicting Prognosis, Immune Microenvironments, and Drug Sensitivity in Hepatocellular Carcinoma

Purpose

Immunogenic cell death (ICD) is a type of regulated cell death that modifies the immune response by releasing DAMPs or danger signals. Herein, we aimed to develop an ICD-related predictive model for patients with hepatocellular carcinoma (HCC) and investigate its applicability for predicting prognostic outcomes and immunotherapeutic responses.

Methods

Differentially expressed genes of ICD were identified in the HCC and normal liver samples. A prognostic risk model and a nomogram containing clinicopathological features were created. To validate the effectiveness of the model, an external dataset was used. Clinical characteristics, prognosis, tumor mutation burden, immune microenvironments, biological function and chemotherapeutic drug sensitivity were evaluated for different genetic subtypes and risk groups.

Results

A total of 35 ICD-related genes (ICDRGs) were identified between HCC and normal samples, 11 of which were significantly associated with overall survival (OS) in HCC patients. Four different genetic subtypes were formed and eight ICDRGs were selected to develop a risk prognostic model. The risk scores were shown to be an independent prognostic factor for HCC and positively correlated with pathological severity. Patients in the high-risk group had a higher frequency of TP53 mutations, increased expression of immune checkpoints and human leukocyte antigen genes. The inhibitory concentrations of chemotherapeutic drugs differed in different populations.

Conclusion

In this study, we developed an ICDRG risk model and demonstrated its applicability in predicting survival outcomes, immune and chemotherapeutic responses in HCC patients. ICDRGs are expected to be used as novel biomarkers in the medical decision-making of HCC.

Understanding the Role of Connexins in Hepatocellular Carcinoma: Molecular and Prognostic Implications

Connexins, a family of tetraspan membrane proteins forming intercellular channels localized in gap junctions, play a pivotal role at the different stages of tumor progression presenting both pro- and anti-tumorigenic effects. Considering the potential role of connexins as tumor suppressors through multiple channel-independent mechanisms, their loss of expression may be associated with tumorigenic activity, while it is hypothesized that connexins favor the clonal expansion of tumor cells and promote cell migration, invasion, and proliferation, affecting metastasis and chemoresistance in some cases. Hepatocellular carcinoma (HCC), characterized by unfavorable prognosis and limited responsiveness to current therapeutic strategies, has been linked to gap junction proteins as tumorigenic factors with prognostic value. Notably, several members of connexins have emerged as promising markers for assessing the progression and aggressiveness of HCC, as well as the chemosensitivity and radiosensitivity of hepatocellular tumor cells. Our review sheds light on the multifaceted role of connexins in HCC pathogenesis, offering valuable insights on recent advances in determining their prognostic and therapeutic potential.

Optimal tagging strategies for illuminating expression profiles of genes with different abundance in zebrafish

CRISPR-mediated knock-in (KI) technology opens a new era of fluorescent-protein labeling in zebrafish, a preferred model organism for in vivo imaging. We described here an optimized zebrafish gene-tagging strategy, which enables easy and high-efficiency KI, ensures high odds of obtaining seamless KI germlines and is suitable for wide applications. Plasmid donors for 3'-labeling were optimized by shortening the microhomologous arms and by reducing the number and reversing the sequence of the consensus Cas9/sgRNA binding sites. To allow for scar-less KI across the genome, linearized dsDNA donors with 5'-chemical modifications were generated and successfully incorporated into our method. To refine the germline screen workflow and expedite the screen process, we combined fluorescence enrichment and caudal-fin junction-PCR. Furthermore, to trace proteins expressed at a low abundance, we developed a fluorescent signal amplifier using the transcriptional activation strategy. Together, our strategies enable efficient gene-tagging and sensitive expression detection for almost every gene in zebrafish.

Exploration and validation of a novel signature of seven necroptosis-related genes to improve the clinical outcome of hepatocellular carcinoma

Necroptosis has been reported to be involved in cancer progression and associated with cancer prognosis. However, the prognostic values of necroptosis-related genes (NRGs) in hepatocellular carcinoma (HCC) remain largely unknown. This study aimed to build a signature on the basis of NRGs to evaluate the prognosis of HCC patients. In this study, using bioinformatic analyses of transcriptome sequencing data of HCC (n = 370) from The Cancer Genome Atlas (TCGA) database, 63 differentially expressed NRGs between HCC and adjacent normal tissues were determined. 24 differentially expressed NRGs were found to be related with overall survival (OS). Seven optimum NRGs, determined using Lasso regression and multivariate Cox regression analysis, were used to construct a new prognostic risk signature for predicting the prognosis of HCC patients. Then survival status scatter plots and survival curves demonstrated that the prognosis of patients with high-Riskscore was worse. The prognostic value of this 7-NRG signature was validated by the International Cancer Genome Consortium (ICGC) cohort and a local cohort (Wenzhou, China). Notably, Riskscore was defined as an independent risk factor for HCC prognosis using multivariate cox regression analysis. Immune infiltration analysis suggested that higher macrophage infiltration was found in patients in the high-risk group. Finally, enhanced 7 NRGs were found in HCC tissues by immunohistochemistry. In conclusion, a novel 7-NRG prognostic risk signature is generated, which contributes to the prediction in the prognosis of HCC patients for the clinicians.

Ferroptosis, Necroptosis, and Pyroptosis in Gastrointestinal Cancers: The Chief Culprits of Tumor Progression and Drug Resistance

In recent years, the incidence of gastrointestinal cancers is increasing, particularly in the younger population. Effective treatment is crucial for improving patients' survival outcomes. Programmed cell death, regulated by various genes, plays a fundamental role in the growth and development of organisms. It is also critical for maintaining tissue and organ homeostasis and takes part in multiple pathological processes. In addition to apoptosis, there are other types of programmed cell death, such as ferroptosis, necroptosis, and pyroptosis, which can induce severe inflammatory responses. Notably, besides apoptosis, ferroptosis, necroptosis, and pyroptosis also contribute to the occurrence and development of gastrointestinal cancers. This review aims to provide a comprehensive summary on the biological roles and molecular mechanisms of ferroptosis, necroptosis, and pyroptosis, as well as their regulators in gastrointestinal cancers and hope to open up new paths for tumor targeted therapy in the near future.

Characteristic of molecular subtypes based on PANoptosis-related genes and experimental verification of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a type of liver cancer that originates from liver cells. It is one of the most common types of liver cancer and a leading cause of cancer-related death worldwide. Early detection and treatment can improve the HCC prognosis. Therefore, it is necessary to further improve HCC markers and risk stratification. PANoptosome is a cytoplasmic polymer protein complex that regulates a proinflammatory programmed cell death pathway called "PANoptosis". The role of PANoptosis in HCC remains unclear. In this study, the molecular changes of PANoptosis related genes (PAN-RGs) in HCC were systematically evaluated. We characterized the heterogeneity of HCC by using consensus clustering to identify two distinct subtypes. The two subtypes showed different survival rate, biological function, chemotherapy drug sensitivity and immune microenvironment. After identification of PAN-RG differential expression genes (DEGs), a prognostic model was established by Cox regression analysis using minimum absolute contraction and selection operator (LASSO), and its prognostic value was verified by Cox regression analysis, Kaplan-Meier curve and receiver operating characteristic (ROC) curve. Our own specimens were also used to further validate the prognostic significance and possible clinical value of the selected targets. Subsequently, we conducted a preliminary discussion on the reasons for the influence of the model on the prognosis through TME analysis, drug resistance analysis, TMB analysis and other studies. This study provides a new idea for individualized and precise treatment of HCC.

Identification and validation of necroptosis-related prognostic gene signature and tumor immune microenvironment infiltration characterization in esophageal carcinoma

Background

Esophageal carcinoma (ESCA) is a common malignancy with a poor prognosis. Previous research has suggested that necroptosis is involved in anti-tumor immunity and promotes oncogenesis and cancer metastasis, which in turn affects tumor prognosis. However, the role of necroptosis in ESCA is unclear. This study aimed to investigate the relationships between necroptosis-related genes (NRGs) and ESCA.

Methods and results

The clinical data and gene expression profiles of ESCA patients were extracted from The Cancer Genome Atlas (TCGA), and 159 NRGs were screened from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. We then identified 52 differentially expressed NRGs associated with ESCA and used them for further analysis. Gene ontology (GO) and KEGG functional enrichment analyses showed that these NRGs were mostly associated with the regulation of necroptosis, Influenza A, apoptosis, NOD-like receptor, and NF-Kappa B signaling pathway. Next, univariate and multivariate Cox regression and LASSO analysis were used to identify the correlation between NRGs and the prognosis of ESCA. We constructed a prognostic model to predict the prognosis of ESCA based on SLC25A5, PPIA, and TNFRSF10B; the model classified patients into high- and low-risk subgroups based on the patient’s risk score. Furthermore, the receiver operating characteristic (ROC) curve was plotted, and the model was affirmed to perform moderately well for prognostic predictions. In addition, Gene Expression Omnibus (GEO) datasets were selected to validate the applicability and prognostic value of our predictive model. Based on different clinical variables, we compared the risk scores between the subgroups of different clinical features. We also analyzed the predictive value of this model for drug sensitivity. Moreover, Immunohistochemical (IHC) validation experiments explored that these three NRGs were expressed significantly higher in ESCA tissues than in adjacent non-tumor tissues. In addition, a significant correlation was observed between the three NRGs and immune-cell infiltration and immune checkpoints in ESCA.

Conclusions

In summary, we successfully constructed and validated a novel necroptosis-related signature containing three genes (SLC25A5, PPIA, and TNFRSF10B) for predicting prognosis in patients with ESCA; these three genes might also play a crucial role in the progression and immune microenvironment of ESCA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02423-6.

Construction of a Necroptosis-Related miRNA Signature for Predicting the Prognosis of Patients With Hepatocellular Carcinoma

Background: Many miRNAs have been demonstrated to be associated with the prognosis of hepatocellular carcinoma (HCC). However, how to combine necroptosis-related miRNAs to achieve the best predictive effect in estimating HCC patient survival has not been explored.

Methods: The mRNA and miRNA expression profile were downloaded from a public database (TCGA-LIHC cohort). Necroptosis-related genes were obtained from previous references, and necroptosis-related miRNAs were identified using Pearson analysis. Subsequently, differential expression miRNAs (DEms) were identified in HCC and paracancer normal samples based on necroptosis-related miRNA expression. The whole set with HCC was randomized into a training set and testing set (1:1). LASSO-Cox regression analysis was used to construct an miRNA signature. Multiple statistical methods were used to validate the clinical benefit of signature in HCC patients, including receiver operator characteristic (ROC) curves, Kaplan–Meier survival analyses, and decision curve analysis (DCA). The downstream target genes of miRNAs were obtained from different online tools, and the potential pathways involved in miRNAs were explored. Finally, we conducted RT-qPCR in SK-HEP-1, THLE-3, and HUH-7 cell lines for miRNAs involved in the signature.

Results: The results showed that a total of eight specific necroptosis-related miRNAs were screened between HCC and adjacent tissues in the training set. Subsequently, based on the aforementioned miRNAs, 5-miRNA signature (miR-139-5p, hsa-miR-326, miR-10b-5p, miR-500a-3p, and miR-592) was generated by LASSO-Cox regression analysis. Multivariate Cox regression analysis showed that the risk scores were independent prognostic indicators in each set. The area under curves (AUCs) of 1 year, 3 years, 5 years, and 7 years were high in each set (AUC >0.7). DCA analysis also revealed that the risk score had a potential benefit than other clinical characteristics. Meanwhile, survival analysis showed that the high-risk group showed low survival probabilities. Moreover, the results of enrichment analysis showed that specific miRNAs were mainly enriched in the cAMP signaling pathway and TNF signaling pathway. Finally, the results of RT-qPCR were consistent with the prediction results in public databases.

Conclusion: Our study establishes a robust tool based on 5-necroptosis-related miRNAs for the prognostic management of HCC patients.

Shikonin Inhibits Cell Growth of Sunitinib-Resistant Renal Cell Carcinoma by Activating the Necrosome Complex and Inhibiting the AKT/mTOR Signaling Pathway

Therapy resistance remains a major challenge in treating advanced renal cell carcinoma (RCC), making more effective treatment strategies crucial. Shikonin (SHI) from traditional Chinese medicine has exhibited antitumor properties in several tumor entities. We, therefore, currently investigated SHI's impact on progressive growth and metastatic behavior in therapy-sensitive (parental) and therapy-resistant Caki-1, 786-O, KTCTL-26, and A498 RCC cells. Tumor cell growth, proliferation, clonogenic capacity, cell cycle phase distribution, induction of cell death (apoptosis and necroptosis), and the expression and activity of regulating and signaling proteins were evaluated. Moreover, the adhesion and chemotactic activity of the RCC cells after exposure to SHI were investigated. SHI significantly inhibited the growth, proliferation, and clone formation in parental and sunitinib-resistant RCC cells by G2/M phase arrest through down-regulation of cell cycle activating proteins. Furthermore, SHI induced apoptosis and necroptosis by activating necrosome complex proteins. Concomitantly, SHI impaired the AKT/mTOR pathway. Adhesion and motility were cell line specifically affected by SHI. Thus, SHI may hold promise as an additive option in treating patients with advanced and therapy-resistant RCC.

Connexin32 activates necroptosis through Src-mediated inhibition of caspase 8 in hepatocellular carcinoma

Necroptosis is an alternative form of programmed cell death that generally occurs under apoptosis-deficient conditions. Our previous work showed that connexin32 (Cx32) promotes the malignant progress of hepatocellular carcinoma (HCC) by enhancing the ability of resisting apoptosis in vivo and in vitro. Whether triggering necroptosis is a promising strategy to eliminate the apoptosis-resistant HCC cells with high Cx32 expression remains unknown. In this study, we found that Cx32 expression was positively correlated with the expression of necroptosis protein biomarkers in human HCC specimens, cell lines, and a xenograft model. Treatment with shikonin, a well-used necroptosis inducer, markedly caused necroptosis in HCC cells. Interestingly, overexpressed Cx32 exacerbated shikonin-induced necroptosis, but downregulation of Cx32 alleviated necroptosis in vitro and in vivo. Mechanistically, Cx32 was found to bind to Src and promote Src-mediated caspase 8 phosphorylation and inactivation, which ultimately reduced the activated caspase 8-mediated proteolysis of receptor-interacting serine-threonine protein kinase 1/3, the key molecule for necroptosis activation. In conclusion, we showed that Cx32 contributed to the activation of necroptosis in HCC cells through binding to Src and then mediating the inactivation of caspase 8. The present study suggested that necroptosis inducers could be more favorable than apoptosis inducers to eliminate HCC cells with high expression of Cx32.