Metabolic regulation of homologous recombination repair by MRE11 lactylation.

Lactylation is a lactate-induced post-translational modification best known for its roles in epigenetic regulation. Herein, we demonstrate that MRE11, a crucial homologous recombination (HR) protein, is lactylated at K673 by the CBP acetyltransferase in response to DNA damage and dependent on ATM phosphorylation of the latter. MRE11 lactylation promotes its binding to DNA, facilitating DNA end resection and HR. Inhibition of CBP or LDH downregulated MRE11 lactylation, impaired HR, and enhanced chemosensitivity of tumor cells in patient-derived xenograft and organoid models. A cell-penetrating peptide that specifically blocks MRE11 lactylation inhibited HR and sensitized cancer cells to cisplatin and PARPi. These findings unveil lactylation as a key regulator of HR, providing fresh insights into the ways in which cellular metabolism is linked to DSB repair. They also imply that the Warburg effect can confer chemoresistance through enhancing HR and suggest a potential therapeutic strategy of targeting MRE11 lactylation to mitigate the effects.

Synergistic anticancer effect by targeting CDK2 and EGFR-ERK signaling.

The EGFR-RAS-ERK pathway is one of the most important signaling cascades in cell survival, growth, and proliferation. Aberrant activation of this pathway is a common mechanism in various cancers. Here, we report that CDK2 is a novel regulator of the ERK pathway via USP37 deubiquitinase (DUB). Mechanistically, CDK2 phosphorylates USP37, which is required for USP37 DUB activity. Further, USP37 deubiquitinates and stabilizes ERK1/2, thereby enhancing cancer cell proliferation. Thus, CDK2 is able to promote cell proliferation by activating USP37 and, in turn, stabilizing ERK1/2. Importantly, combined CDK1/2 and EGFR inhibitors have a synergetic anticancer effect through the downregulation of ERK1/2 stability and activity. Indeed, our patient-derived xenograft (PDX) results suggest that targeting both ERK1/2 stability and activity kills cancer cells more efficiently even at lower doses of these two inhibitors, which may reduce their associated side effects and indicate a potential new combination strategy for cancer therapy.

DNA Damage Response Evaluation Provides Novel Insights for Personalized Immunotherapy in Glioma.

Background: DNA damage response (DDR) proficiency is the principal mechanism of temozolomide (TMZ) resistance in glioma. Accumulating evidence has also suggested the determining role of DDR in anticancer immunity. We propose that a comprehensive investigation of the DDR landscape can optimize glioma treatment. Methods: We identified the pronounced enrichment of DDR in TMZ-resistant glioma cells by RNA sequencing. Nine differentially expressed genes between TMZ-sensitive/resistant glioma cells were selected to construct the DDR score through lasso regression analysis. Two glioma cohorts from TCGA and CGGA were interrogated to evaluate the predictive ability of DDR score. Multiple algorithms were applied to estimate the immunotherapeutic responses of two DDR phenotypes. Immunohistochemistry was used to determine the protein levels of PD-L1 and TGFß in glioma specimens. The oncoPredict package was employed to predict the candidate chemotherapy agents. Results: DDR score exhibited a robust prognostic capability in TCGA and CGGA cohorts and served as an independent predictive biomarker in glioma patients. Functional enrichment analyses revealed that high and low DDR score groups were characterized by distinct immune activity and metabolic processes. Elevated levels of infiltrating immune cells (including CD8+ T cells, CD4+ T cells, and dendritic cells) were observed in the high DDR score glioma. Further, high DDR scores correlated with increased mutation burden, up-regulated immune checkpoints, and tumor immunity activation, indicating a profound interplay between DDR score and glioma immunogenicity. In addition, PD-L1 and TGFß were overexpressed in recurrent glioma specimens compared with primary ones. Finally, we estimated that PI3K inhibitors may serve as latent regimens for high DDR score patients. Conclusion: Our study highlighted the promising prognostic role of DDR score in glioma. Individual assessment of DDR status for patients with glioma may provide new clues for developing immunotherapeutic strategies.

Flap endonuclease 1 and DNA-PKcs synergistically participate in stabilizing replication fork to encounter replication stress in glioma cells.

BACKGROUND: Selectively utilizing alternative mechanisms to repair damaged DNA in essential factors deficient cancer facilitates tumor genetic evolution and contributes to treatment resistance. Synthetic lethality strategies provide a novel scenario to anticancer therapy with DNA repair protein mutation, such as glioma with DNA-PKcs-deficiency, a core factor crucial for non-homologous end joining (NHEJ) mediated DNA damage repair. Nevertheless, the clinical significance and molecular mechanisms of synthetic lethality function by interfering tumor DNA replication remain largely unexplored. METHODS: Cancer clinic treatment resistance-related replication core factors were identified through bioinformatics analysis and RNA-sequencing and verified in clinical specimens by immunoblotting and in situ Proximity Ligation Analysis (PLA). Then, in vitro and in vivo experiments, including visible single molecular tracking system were performed to determine functional roles, the molecular mechanisms and clinical significance of synthetic lethality on glioma tumors. RESULTS: Hyperactive DNA replication and regulator Flap endonuclease 1 (FEN1) provides high efficiency DNA double strand breaks (DSB) repair abilities preventing replication forks collapse during DNA replication which facilitate adaptation to selective pressures. DNA-PKcs deficient glioma cells are highly dependent on FEN1/BRCA1/RAD51 to survival and counteract replication stress. FEN1 protects perturbed forks from erroneous over-resection by MRE11 through regulating of BRCA1-RAD51 and WRN helicase, uncovering an essential genetic interaction between FEN1 and DNA-PKcs in mitigating replication-stress induced tumor genomic instability. Therapeutically, genetic depletion or molecular inhibition of FEN1 and DNA-PKcs perturb glioma progression. CONCLUSIONS: Our findings highlight an unanticipated synthetic interaction between FEN1/BRCA1/RAD51 and DNA-PKcs when dysfunction leads to incompatible with cell survival under conditions of interrupted replication progression by disrupting addictive alternative tumor evolution and demonstrate the applicability of combined FEN1 and DNA-PKcs targeting in the treatment of glioma.

RECQ1 Promotes Stress Resistance and DNA Replication Progression Through PARP1 Signaling Pathway in Glioblastoma.

Glioblastoma (GBM) is the most common aggressive primary malignant brain tumor, and patients with GBM have a median survival of 20 months. Clinical therapy resistance is a challenging barrier to overcome. Tumor genome stability maintenance during DNA replication, especially the ability to respond to replication stress, is highly correlated with drug resistance. Recently, we identified a protective role for RECQ1 under replication stress conditions. RECQ1 acts at replication forks, binds PCNA, inhibits single-strand DNA formation and nascent strand degradation in GBM cells. It is associated with the function of the PARP1 protein, promoting PARP1 recruitment to replication sites. RECQ1 is essential for DNA replication fork protection and tumor cell proliferation under replication stress conditions, and as a target of RECQ1, PARP1 effectively protects and restarts stalled replication forks, providing new insights into genomic stability maintenance and replication stress resistance. These findings indicate that tumor genome stability targeting RECQ1-PARP1 signaling may be a promising therapeutic intervention to overcome therapy resistance in GBM.

Genomic Analysis Uncovers Immune Microenvironment Characteristics and Drug Sensitivity of Ferroptosis in Breast Cancer Brain Metastasis.

Background: The role of ferroptosis in breast cancer brain metastasis (BCBM) is unclear. This study aimed to explore the ferroptosis-related genes (FRG) relations with the tumor microenvironment, as well as evaluate their values in predicting survival and drug sensitivity in patients with BCBM. Materials and Methods: Genes expression and clinical data were downloaded from Gene Expression Omnibus (GEO). Univariate and multivariate Cox regression analyses were performed to explore the independent prognostic factors. Consensus cluster principal component analysis (PCA) was used to establish the ferroptosis score. Immunological signatures were analyzed by the single-sample gene set enrichment analysis (ssGSEA). Drug sensitivity was evaluated through the estimated half-maximal inhibitory concentration (IC50). Finally, results were validated in external cohorts. Results: Fourteen significantly different FRG were identified between breast cancer (BC) and BCBM tissues. Survival analysis demonstrated HMOX1, PEBP1, KEAP1, and LPCAT3 were significantly associated with overall survival (OS) and relapse-free survival (RFS) (all p < 0.05). High ferroptosis score was correlated with iron ion homeostasis, iron metabolism, higher stromal cells and immune cells scores. Patients with high- and low-ferroptosis scores were characterized by different drug sensitivities. Following external validations, the ferroptosis had distinct expression profiles between the BC and BCBM, and could serve as biomarkers for OS and drug response. Conclusion: Our findings suggested that ferroptosis may be involved in the process of BCBM, and ferroptosis could serve as prognostic biomarkers. Evaluation of ferroptosis may deepen our understanding about the tumor microenvironment, and could help clinicians to make individualized therapy.

Two machine learning methods identify a metastasis-related prognostic model that predicts overall survival in medulloblastoma patients.

Approximately 30% of medulloblastoma (MB) patients exhibit metastasis at initial diagnosis, which often leads to a poor prognosis. Here, by using univariate Cox regression analysis, two machine learning methods (Lasso-penalized Cox regression and random survival forest-variable hunting (RSF-VH)), and multivariate Cox regression analysis, we established two metastasis-related prognostic models, including the 47-mRNA-based model based on the Lasso method and the 21-mRNA-based model based on the RSF-VH method. In terms of the results of the receiver operating characteristic (ROC) curve analyses, we selected the 47-mRNA metastasis-associated model with the higher area under the curve (AUC). The 47-mRNA-based prognostic model could classify MB patients into two subgroups with different prognoses. The ROC analyses also suggested that the 47-mRNA metastasis-associated model may have a better predictive ability than MB subgroup. Multivariable Cox regression analysis demonstrated that the 47-mRNA-based model was independent of other clinical characteristics. In addition, a nomogram comprising the 47-mRNA-based model was built. The results of ROC analyses suggested that the nomogram had good discrimination ability. Our 47-mRNA metastasis-related prognostic model and nomogram might be an efficient and valuable tool for overall survival (OS) prediction and provide information for individualized treatment decisions in patients with MB.

Structural and Functional Overview of TEAD4 in Cancer Biology.

TEA domain transcription factor 4 (TEAD4) is an important member of the TEAD family. As a downstream effector of the Hippo pathway, TEAD4 has essential roles in cell proliferation, cell survival, tissue regeneration, and stem cell maintenance. TEAD4 contains a TEA DNA binding domain that binds the promoters of target genes and a Yes-associated protein/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) binding domain that associates with transcriptional cofactors. TEAD4 coordinates with YAP, TAZ, VGLL, and other transcription factors to regulate different cellular processes in cancer via its transcriptional output. Moreover, TEAD4 undergoes post-translational modifications and subcellular translocations, and both processes have been shown to shed new insights on how TEAD transcriptional activity can be modified. In summary, TEAD4 has important roles in cancer, including epithelial-mesenchymal transition (EMT), metastasis, cancer stem cell dynamics, and chemotherapeutic drug resistance, suggesting that TEAD4 may be a promising prognostic biomarker in cancer.

Comparison of Tacrolimus and Cyclosporine Combined With Methotrexate for Graft Versus Host Disease Prophylaxis After Allogeneic Hematopoietic Cell Transplantation.

BACKGROUND: After patients receive hematopoietic stem cell transplantation (HSCT), both cyclosporine (CsA) and tacrolimus (TAC) in combination with methotrexate (MTX) are recommended as the standard prophylaxis strategy for graft versus host disease (GVHD) by the European Group of Blood and Marrow Transplantation. However, the advantage of TAC combined with MTX lacks conclusive evidence. METHODS: We searched online databases for studies comparing CsA + MTX and TAC + MTX in patients who received HSCT. The odds ratio (OR) and 95% confidence interval (CI) were applied to compare the pooled data. RESULTS: We found a significant reduction in the grade II to IV acute GVHD (aGVHD) rate (OR, 0.42; CI, 0.28-0.61; P < 0.00001), grade III to IV aGVHD rate (OR, 0.59; CI, 0.38-0.92; P = 0.02), chronic GVHD rate (OR, 0.79; CI, 0.62-1.00; P = 0.05), and nonrelapse mortality rate (OR, 0.62; CI, 0.40-0.95; P = 0.03) and an increase in the overall survival (OS) rate (only in those received from unrelated donor) (OR, 1.30; CI, 1.15-1.48; P < 0.0001) in the TAC + MTX group. Similar outcomes occurred for the relapse rate and disease-free survival rate in both groups. CONCLUSIONS: TAC + MTX has a superior effect in the prevention of aGVHD in patients who received HSCT and further prolongs the OS in patients who received from unrelated donor transplants. CsA + MTX prolongs the OS in patients who received HSCT from HLA-identical sibling donors. The leukemic relapse and disease-free survival rate were not different between the 2 regimens. Thus, we conclude that TAC + MTX was superior to CsA + MTX, especially for HSCT patients with nonmalignant disorders. Further studies are still required to evaluate the effect of TAC or CsA combined with other suppressors in the treatment regimen following HSCT.

Once-daily prolonged-release tacrolimus versus twice-daily tacrolimus in liver transplantation.

OBJECTIVE: For patients who have received a kidney transplant, studies have shown that once-daily prolonged-release tacrolimus (TAC) has similar efficacy and safety to standard twice-daily dosing. The purpose of this study was to perform a meta-analysis to compare the effectiveness and safety of daily TAC (TAC qd) versus standard twice-daily TAC (TAC bid) administration in liver transplantation (LT). DESIGN: Meta-analysis. SETTING AND PARTICIPANTS: We systematically searched the PubMed/MEDLINE, Web of Science, and Cochrane Library databases for studies comparing outcomes of LT patients who received TAC qd versus TAC bid. OUTCOME MEASURES: Results were reported as odds ratios (ORs) with 95% CIs. RESULTS: Six studies, which included 5179 LT recipients (TAC qd = 951; TAC bid = 4228) were included in the analysis. The TAC qd group had a low 1-year graft loss rate (OR 0.70 [95% CI 0.54-0.91], P = 0.008) and lower rate of biopsy-proven acute rejection (BPAR) at 90 days (OR 0.46 [95% CI 0.24-0.89], P = 0.02) compared with the TAC bid group. There was no significant difference in 1-year mortality or the incidence of adverse events after LT between the 2 groups. CONCLUSIONS: Current evidence suggests that TAC qd is safe and effective for LT patients during the first year after transplantation. Longer-term follow-up studies are necessary to determine if TAC qd is safe and effective beyond the first year after LT.

The Association of obesity with vascular complications after liver transplantation.

BACKGROUND: Because of the growing number of obese patients undergoing liver transplantation (LT), it is important to investigate the impact of obesity on post-transplant outcomes. Vascular complications are rare, but serious causes of morbidity and mortality after LT. It is not known if pre-transplant obesity is associated with an increased incidence of post-LT vascular complications. METHODS: Medline, Embase, and Cochrane Library databases were searched in September 2017. The primary outcome was the impact of obesity on the vascular complication rate in adult LT recipients. Survival and biliary complications rates were also analyzed. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated to compare pooled data between groups with a body mass index (BMI) ≥ 30 kg/m2 and < 30 kg/m2. RESULTS: Six retrospective cohort studies with a total of 987 patients with a BMI ≥ 30 kg/m2 (high BMI group) and 2911 patients with a BMI < 3 0 kg/m2 (control group) were included in the analysis. All studies had Newcastle-Ottawa Scale scores ≥4. The vascular complication rates were similar between the high BMI group and control group (RR = 1.13, 95% CI: 0.87-1.47, P = 0.27), as were the patient survival, graft survival, and biliary complication rates. In subgroup analysis, there was no difference in the vascular complication rates between BMI ≥ 35 vs. BMI < 25 kg/m2; BMI 30-35 vs. BMI 18-25 kg/m2; BMI ≥ 30 vs. BMI 18-25 kg/m2; and BMI ≥ 35 vs. BMI < 35 kg/m2. No difference was found in subgroup analysis when BMI was adjusted for ascites. However, recipients whose primary disease was alcoholic liver disease, those with a BMI ≥ 30 kg/m2 had higher incidence of vascular complications than those with a BMI < 30 kg/m2 (RR = 1.55, 95% CI: 1.07-2.25, P = 0.02) . CONCLUSIONS: BMI does not affect incidence of vascular complications after LT. High pre-transplant BMI is not a risk factor for patient survival and biliary complications after LT.

The early outcomes of candidates with portopulmonary hypertension after liver transplantation.

BACKGROUND: Portopulmonary hypertension (PPH) was once regarded as a contraindicaton to liver transplantation (LT). However, growing evidence has indicated that PPH patients undergoing LT may show similar outcomes compared to those without PPH, and researchers have recommended it not be an absolute contraindication. Given this controversy, we aimed to identify and review the current evidence on this topic and to provide a comparison of the outcomes after LT between candidates with PPH and those without. METHODS: We systematically searched the MEDLINE, EMBASE and Cochrane Library databases for all studies that compared the outcomes of PPH patients and those without PPH after LT. All studies reporting outcomes of PPH patients versus those without PPH (Control) were further considered for inclusion in this meta-analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to compare the pooled data between PPH and Control groups. RESULTS: Eleven retrospective trials and one prospective, randomized, controlled trial, involving 37,686 transplant recipients were included. The PPH patients had increased 1-year mortality with an OR of 1.59 (95% CI = 1.26-2.01, P = 0.0001) compared to the control group. There was no significant difference in graft loss and 30-day mortality after LT between the two groups. CONCLUSIONS: Patients with PPH who underwent LT had increased 1-year mortality compared to those without PPH, while graft loss and 30-day mortality were similar. Nevertheless, LT may be a reasonable therapeutic option for some patients with PPH, but further studies are needed to identify those select patients with PPH who would benefit most from LT.