SOCS2-enhanced ubiquitination of SLC7A11 promotes ferroptosis and radiosensitization in hepatocellular carcinoma

SDC1-TGM2-FLOT1-BHMT complex determines radiosensitivity of glioblastoma by influencing the fusion of autophagosomes with lysosomes

Rationale: Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults. Radiotherapy has long been an important treatment for GBM. Despite recent advances in tumor radiotherapy, the prognosis of GBM remains poor due to radioresistance. Autophagy has been reported as a basic factor to prolong the survival of tumor under radiation stress, but the molecular mechanism of how autophagy contributes to GBM radioresistance was still lacking. Methods: We established radioresistant GBM cells and identified their protein profiles by Tandem mass tag (TMT) quantitative proteomic analysis, then chose the radioresistant genes based on the TMT analysis of GBM cells and differentially expressed genes (DEGs) analysis of GEO database. Colony formation, flow cytometry, qPCR, western blotting, mRFP-GFP-LC3, transmission electron microscopy, immunofluorescence, and co-IP assays were conducted to investigate the regulation mechanisms among these new-found molecules. Results: Syndecan 1 (SDC1) and Transglutaminase 2 (TGM2) were both overexpressed in the radioresistant GBM cells and tissues, contributing to the dismal prognosis of radiotherapy. Mechanically, after irradiation, SDC1 carried TGM2 from cell membrane into cytoplasm, and transported to lysosomes by binding to flotillin 1 (FLOT1), then TGM2 recognized the betaine homocysteine methyltransferase (BHMT) on autophagosomes to coordinate the encounter between autophagosomes and lysosomes. Conclusions: The SDC1-TGM2-FLOT1-BHMT copolymer, a novel member of the protein complexes involved in the fusion of lysosomes and autophagosomes, maintained the autophagic flux in the irradiated tumor cells and ultimately enhanced radioresistance of GBM, which provides new insights of the molecular mechanism and therapeutic targets of radioresistant GBM.

Radiotherapy-induced ferroptosis for cancer treatment

Ferroptosis is a regulated cell death mechanism controlled by iron, amino acid and reactive oxygen species metabolisms, which is very relevant for cancer therapy. Radiotherapy-induced ferroptosis is critical for tumor suppression and several preclinical studies have demonstrated that the combination of ionizing radiation with small molecules or nano-systems is effective in combating cancer growth and overcoming drug or ionizing radiation resistance. Here, we briefly overview the mechanisms of ferroptosis and the cross-talk existing between the cellular pathways activated by ferroptosis and those induced by radiotherapy. Lastly, we discuss the recently reported combinational studies involving radiotherapy, small molecules as well as nano-systems and report the recent findings achieved in this field for the treatment of tumors.

Genetic polymorphisms in genes regulating cell death and prognosis of patients with rectal cancer receiving postoperative chemoradiotherapy

OBJECTIVE

The identification of biomarkers for predicting chemoradiotherapy efficacy is essential to optimize personalized treatment. This study determined the effects of genetic variations in genes involved in apoptosis, pyroptosis, and ferroptosis on the prognosis of patients with locally advanced rectal cancer receiving postoperative chemoradiotherapy (CRT).

METHODS

The Sequenom MassARRAY was used to detect 217 genetic variations in 40 genes from 300 patients with rectal cancer who received postoperative CRT. The associations between genetic variations and overall survival (OS) were evaluated using hazard ratios (HRs) and 95% confidence intervals (CIs) computed using a Cox proportional regression model. Functional experiments were performed to determine the functions of the arachidonate 5-lipoxygenase (ALOX5) gene and the ALOX5 rs702365 variant.

RESULTS

We detected 16 genetic polymorphisms in CASP3, CASP7, TRAILR2, GSDME, CASP4, HO-1, ALOX5, GPX4, and NRF2 that were significantly associated with OS in the additive model (P < 0.05). There was a substantial cumulative effect of three genetic polymorphisms (CASP4 rs571407, ALOX5 rs2242332, and HO-1 rs17883419) on OS. Genetic variations in the CASP4 and ALOX5 gene haplotypes were associated with a higher OS. We demonstrated, for the first time, that rs702365 [G] > [C] represses ALOX5 transcription and corollary experiments suggested that ALOX5 may promote colon cancer cell growth by mediating an inflammatory response.

CONCLUSIONS

Polymorphisms in genes regulating cell death may play essential roles in the prognosis of patients with rectal cancer who are treated with postoperative CRT and may serve as potential genetic biomarkers for individualized treatment.

Ubiquitin-proteasome system-based signature to predict the prognosis and drug sensitivity of hepatocellular carcinoma

Background: Ubiquitin-proteasome system (UPS) is implicated in cancer occurrence and progression. Targeting UPS is emerging as a promising therapeutic target for cancer treatment. Nevertheless, the clinical significance of UPS in hepatocellular carcinoma (HCC) has not been entirely elucidated. Methods: Differentially expressed UPS genes (DEUPS) were screened from LIHC-TCGA datasets. The least absolute shrinkage and selection operator (LASSO) and stepwise multivariate regression analysis were conducted to establish a UPS-based prognostic risk model. The robustness of the risk model was further validated in HCCDB18, GSE14520, and GSE76427 cohorts. Subsequently, immune features, clinicopathologic characteristics, enrichment pathways, and anti-tumor drug sensitivity of the model were further evaluated. Moreover, a nomogram was established to improve the predictive ability of the risk model. Results: Seven UPS-based signatures (ATG10, FBXL7, IPP, MEX3A, SOCS2, TRIM54, and PSMD9) were developed for the prognostic risk model. Individuals with HCC with high-risk scores presented a more dismal prognosis than those with low-risk scores. Moreover, larger tumor size, advanced TNM stage, and tumor grade were observed in the high-risk group. Additionally, cell cycle, ubiquitin-mediated proteolysis, and DNA repair pathways were intimately linked to the risk score. In addition, obvious immune cell infiltration and sensitive drug response were identified in low-risk patients. Furthermore, both nomogram and risk score showed a significant prognosis-predictive ability. Conclusion: Overall, we established a novel UPS-based prognostic risk model in HCC. Our results will facilitate a deep understanding of the functional role of UPS-based signature in HCC and provide a reliable prediction of clinical outcomes and anti-tumor drug responses for patients with HCC.

The role of lipid metabolism in cancer radioresistance

Radiotherapy is one of the main therapies for cancer. The process leading to radioresistance is still not fully understood. Cancer radiosensitivity is related to the DNA reparation of cancer cells and the tumor microenvironment (TME), which supports cancer cell survival. Factors that affect DNA reparation and the TME can directly or indirectly affect the radiosensitivity of cancer. Recent studies have shown that lipid metabolism in cancer cells, which is involved in the stability of cell membrane structure, energy supply and signal transduction of cancer cells, can also affect the phenotype and function of immune cells and stromal cells in the TME. In this review, we discussed the effects of lipid metabolism on the radiobiological characteristics of cancer cells and the TME. We also summarized recent advances in targeted lipid metabolism as a radiosensitizer and discussed how these scientific findings could be translated into clinical practice to improve the radiosensitivity of cancer.

The Ubiquitin-Proteasome System in Tumor Metabolism

Metabolic reprogramming, which is considered a hallmark of cancer, can maintain the homeostasis of the tumor environment and promote the proliferation, survival, and metastasis of cancer cells. For instance, increased glucose uptake and high glucose consumption, known as the "Warburg effect," play an essential part in tumor metabolic reprogramming. In addition, fatty acids are harnessed to satisfy the increased requirement for the phospholipid components of biological membranes and energy. Moreover, the anabolism/catabolism of amino acids, such as glutamine, cystine, and serine, provides nitrogen donors for biosynthesis processes, development of the tumor inflammatory environment, and signal transduction. The ubiquitin-proteasome system (UPS) has been widely reported to be involved in various cellular biological activities. A potential role of UPS in the metabolic regulation of tumor cells has also been reported, but the specific regulatory mechanism has not been elucidated. Here, we review the role of ubiquitination and deubiquitination modification on major metabolic enzymes and important signaling pathways in tumor metabolism to inspire new strategies for the clinical treatment of cancer.

Tubastatin A potently inhibits GPX4 activity to potentiate cancer radiotherapy through boosting ferroptosis

Ferroptosis, an iron-dependent lipid peroxidation-driven programmed cell death, is closely related to cancer therapy. The development of druggable ferroptosis inducers and their rational application in cancer therapy are critical. Here, we identified Tubastatin A, an HDAC6 inhibitor as a novel druggable ferroptosis inducer through large-scale drug screening. Tubastatin A directly bonded to GPX4 and inhibited GPX4 enzymatic activity through biotin-linked Tubastatin A putdown and LC/MS analysis, which is independent of its inhibition of HDAC6. In addition, our results showed that radiotherapy not only activated Nrf2-mediated GPX4 transcription but also inhibited lysosome-mediated GPX4 degradation, subsequently inducing ferroptosis tolerance and radioresistance in cancer cells. Tubastatin A overcame ferroptosis resistance and radioresistance of cancer cells by inhibiting GPX4 enzymatic activity. More importantly, Tubastatin A has excellent bioavailability, as demonstrated by its ability to significantly promote radiotherapy-induced lipid peroxidation and tumour suppression in a mouse xenograft model. Our findings identify a novel druggable ferroptosis inducer, Tubastatin A, which enhances radiotherapy-mediated antitumor effects. This work provides a compelling rationale for the clinical evaluation of Tubastatin A, especially in combination with radiotherapy.

Ferroptosis and its interaction with tumor immune microenvironment in liver cancer

Exploring effective systemic treatments for liver cancer is still a great challenge worldwide. As a novel form of regulated cell death, ferroptosis has been paid more and more attention in the cancer research field. In recent years, targeting ferroptosis has become an encouraging strategy for liver cancer treatment. Cancer cells can be directly killed by inducing ferroptosis; in contrast, ferroptosis can also ameliorate the tumor immunosuppressive microenvironment and sensitize cancers to immunotherapy. Here, we summarize fully current progress in the iron homeostasis in the liver, the internal association between imbalanced iron homeostasis and ferroptosis in liver carcinogenesis and development, as well as ferroptosis-related regulators in liver cancer. Furthermore, we discuss thoroughly the interaction between ferroptosis and tumor immune microenvironment. Finally, we provide certainly a future insight on the potential value of ferroptosis in the immunotherapy of liver cancer.

Characterization of cellular senescence patterns predicts the prognosis and therapeutic response of hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is a prevalent malignancy with a high mortality rate. Cellular senescence, an irreversible state of cell cycle arrest, plays a paradoxical role in cancer progression. Here, we aimed to identify Hepatocellular carcinoma subtypes by cellular senescence-related genes (CSGs) and to construct a cellular senescence-related gene subtype predictor as well as a novel prognostic scoring system, which was expected to predict clinical outcomes and therapeutic response of Hepatocellular carcinoma. Methods: RNA-seq data and clinical information of Hepatocellular carcinoma patients were derived from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC). The "multi-split" selection was used to screen the robust prognostic cellular senescence-related genes. Unsupervised clustering was performed to identify CSGs-related subtypes and a discriminant model was obtained through multiple statistical approaches. A CSGs-based prognostic model-CSGscore, was constructed by LASSO-Cox regression and stepwise regression. Immunophenoscore (IPS) and Tumor Immune Dysfunction and Exclusion (TIDE) were utilized to evaluate the immunotherapy response. Tumor stemness indices mRNAsi and mDNAsi were used to analyze the relationship between CSGscore and stemness. Results: 238 robust prognostic differentially expressed cellular senescence-related genes (DECSGs) were used to categorize all 336 hepatocellular carcinoma patients of the TCGA-LIHC cohort into two groups with different survival. Two hub genes, TOP2A and KIF11 were confirmed as key indicators and were used to form a precise and concise cellular senescence-related gene subtype predictor. Five genes (PSRC1, SOCS2, TMEM45A, CCT5, and STC2) were selected from the TCGA training dataset to construct the prognostic CSGscore signature, which could precisely predict the prognosis of hepatocellular carcinoma patients both in the training and validation datasets. Multivariate analysis verified it as an independent prognostic factor. Besides, CSGscore was also a valuable predictor of therapeutic responses in hepatocellular carcinoma. More downstream analysis revealed the signature genes were significantly associated with stemness and tumor progression. Conclusion: Two subtypes with divergent outcomes were identified by prognostic cellular senescence-related genes and based on that, a subtype indicator was established. Moreover, a prognostic CSGscore system was constructed to predict the survival outcomes and sensitivity of therapeutic responses in hepatocellular carcinoma, providing novel insight into hepatocellular carcinoma biomarkers investigation and design of tailored treatments depending on the molecular characteristics of individual patients.

A Novel Ferroptosis-Related Signature for Prediction of Prognosis, Immune Profiles and Drug Sensitivity in Hepatocellular Carcinoma Patients

Hepatocellular carcinoma (HCC) is a malignant disease with an increasing incidence and a high mortality rate. Ferroptosis, a novel type of cell death, has been reported to be closely associated with the progression of HCC. The aim of our study was to construct a novel ferroptosis-related signature (nFRGs) for prediction of prognosis, immune features and drug sensitivity of HCC patients. Data were obtained from the TCGA, ICGC, GSE104580, CCLE and IMvigor210 datasets, and the least absolute shrinkage and selection operator (LASSO) was used to construct nFRGs. In addition, the analyses involved in prognoses, molecular function, stemness indices, somatic mutation, responses to immunologic therapy, efficacy of transcatheter arterial chemoembolization (TACE) therapy and drug sensitivity were performed using diverse packages of R 4.1.3 between the low- and high-risk groups. The nFRGs included seven ferroptosis-related genes. Our results showed that nFRGs was an independent risk factor for prognoses of HCC patients, and HCC patients in the high-risk group presented with worse prognosis. Compared with the results of other studies, nFRGs was superior to other promising signatures in predicting prognoses of patients with HCC. In addition, most of the enriched pathways of differentially expressed genes (DEGs) between these subgroups were related to immune features. The molecular functions, genetic mutation and mRNAsi were varied between the high- and low-risk groups. Moreover, we observed significant immunosuppression state in the high-risk group. Patients in the high-risk group might benefit from immunotherapy, whereas patients in the low-risk group may be susceptible to TACE therapy. Finally, five sensitive drugs and four sensitive drugs were screened for patients in the high- and low-risk groups, respectively. nFRGs may served as a novel biomarker of prognosis and aid in personalized therapeutic strategies for patients with HCC.