Germline mutations in a DNA repair pathway are associated with familial colorectal cancer

CHEK2 deficiency increase the response to PD-1 inhibitors by affecting the tumor immune microenvironment

Immune checkpoint blockade (ICB) therapy has improved treatment effects in multiple cancers. Gene mutations in the DNA damage repair pathway (DDR) may cause genomic instability and may relate to the efficacy of ICB. Checkpoint kinase 2 (CHEK2) and polymerase epsilon (POLE) are important genes in the DDR. In this study, we aimed to study the impact of CHEK2 deficiency mutations on the response to ICB. We found that tumors with CHEK2 mutations had a significantly higher tumor mutational burden (TMB) compared to those with CHEK2-WT in a pancancer database. We noted that CHEK2 deficiency mutations potentiated the anti-tumor effect of anti-PD-1 therapy in MC38 and B16 tumor-bearing mice with the decrease of tumor volume and tumor weight after anti-PD-1 treatment. Mechanistically, CHEK2 deficiency tumors were with the increased cytotoxic CD8+ T-cell infiltration, especially cytotoxic CD8+ T cells, and modulated the tumor-immune microenvironment with an upregulated immune inflammatory pathway and antigen presentation pathway after anti-PD-1 treatment. Furthermore, murine models with POLE mutations confirmed that CHEK2 deficiency shaped similar mutational and immune landscapes as POLE mutations after anti-PD-1 treatment. Taken together, our results demonstrated that CHEK2 deficiency mutations may increase the response to ICB (eg. anti-PD-1) by influencing the tumor immune microenvironment. This indicated that CHEK2 deficiency mutations were a potentially predictive biomarker and CHEK2 deficiency may potentiate response to immunotherapy.

Aberrant β-Catenin Expression and Its Association With Epithelial-Mesenchymal Transition and Clinical Outcomes of Colorectal Cancer

Background Colorectal cancer (CRC) is a significant global health challenge with high mortality rates. Dysregulation of β-catenin, epithelial-mesenchymal transition (EMT), and adenomatous polyposis coli (APC) are crucial in CRC development. Mutations in the APC gene lead to aberrant β-catenin expression, a key player in CRC pathogenesis. β-catenin not only influences canonical Wnt signaling but also regulates EMT. This study investigated the correlation between APC mutations, β-catenin dysregulation, and EMT induction in CRC. Methodology Tissue samples from 96 CRC patients and 40 para-cancerous normal tissues were collected and subjected to immunohistochemistry to assess β-catenin, E-cadherin, ZEB1, Snail, and vimentin expression. Genomic DNA was extracted and analyzed for APC mutations. Next-generation sequencing was employed for data analysis. Results Aberrant β-catenin expression was found in 82.3% of CRC cases and correlated with advanced clinicopathological factors. Aberrant β-catenin expression was associated with age (p=0.01), tumor invasion depth (p=0.03), nodal/distant metastasis (p=0.001 and 0.004), and vascular invasion (p=0.001). Aberrant β-catenin was correlated with EMT status. A positive correlation was observed between aberrant β-catenin expression and ZEB1 (p=0.001), Snail (p=0.001), vimentin (p=0.001), and loss of membranous E-cadherin (p=0001). Coexistence of aberrant β-catenin and EMT markers was associated with advanced CRC progression. Cancerous tissues displayed higher aberrant β-catenin and EMT markers expression than para-cancerous tissues. APC mutations were present in 59.3% of cases, with 91.2% of mutated APC cases showing aberrant β-catenin expression. The coexistence of APC mutation and aberrant β-catenin expression was correlated with the clinical outcomes of CRC patients. Mutated APC cases exhibited significantly increased EMT marker expression. Conclusion This study underscores the importance of aberrant β-catenin expression in CRC progression, linked to APC mutations and EMT induction. Understanding these relationships could aid in developing targeted therapies for CRC.

CRISPR/Cas9: a powerful tool in colorectal cancer research

Colorectal cancer (CRC) is one of the most common malignant cancers worldwide and seriously threatens human health. The clustered regulatory interspaced short palindromic repeat/CRISPR-associate nuclease 9 (CRISPR/Cas9) system is an adaptive immune system of bacteria or archaea. Since its introduction, research into various aspects of treatment approaches for CRC has been accelerated, including investigation of the oncogenes, tumor suppressor genes (TSGs), drug resistance genes, target genes, mouse model construction, and especially in genome-wide library screening. Furthermore, the CRISPR/Cas9 system can be utilized for gene therapy for CRC, specifically involving in the molecular targeted drug delivery or targeted knockout in vivo. In this review, we elucidate the mechanism of the CRISPR/Cas9 system and its comprehensive applications in CRC. Additionally, we discussed the issue of off-target effects associated with CRISPR/Cas9, which serves to restrict its practical application. Future research on CRC should in-depth and systematically utilize the CRISPR/Cas9 system thereby achieving clinical practice.

Prognosis-Related Molecular Subtypes and Immune Features Associated with Hepatocellular Carcinoma

Bioinformatics tools were used to identify prognosis-related molecular subtypes and biomarkers of hepatocellular carcinoma (HCC). Differential expression analysis of four datasets identified 3330 overlapping differentially expressed genes (DEGs) in the same direction in all four datasets. Those genes were involved in the cell cycle, FOXO signaling pathway, as well as complement and coagulation cascades. Based on non-negative matrix decomposition, two molecular subtypes of HCC with different prognoses were identified, with subtype C2 showing better overall survival than subtype C1. Cox regression and Kaplan-Meier analysis showed that 217 of the overlapping DEGs were closely associated with HCC prognosis. The subset of those genes showing an area under the curve >0.80 was used to construct random survival forest and least absolute shrinkage and selection operator models, which identified seven feature genes (SORBS2, DHRS1, SLC16A2, RCL1, IGFALS, GNA14, and FANCI) that may be involved in HCC occurrence and prognosis. Based on the feature genes, risk score and recurrence models were constructed, while a univariate Cox model identified FANCI as a key gene involved mainly in the cell cycle, DNA replication, and mismatch repair. Further analysis showed that FANCI had two mutation sites and that its gene may undergo methylation. Single-sample gene set enrichment analysis showed that Th2 and T helper cells are significantly upregulated in HCC patients compared to controls. Our results identify FANCI as a potential prognostic biomarker for HCC.

A Previously Unrecognized Molecular Landscape of Lynch Syndrome in the Mexican Population

Lynch syndrome (LS) is the main hereditary colorectal cancer syndrome. There have been few reports regarding the clinical and molecular characteristics of LS patients in Latin America; this is particularly true in the Mexican population, where no information is available. The present study aims to describe the clinical and molecular spectrum of variants in a cohort of patients diagnosed with LS in Mexico. We present a retrospective analysis of 412 patients with suspected LS, whose main site of cancer diagnosis was the colon (58.25%), followed by the endometrium (18.93%). Next-generation sequencing analysis, with an extensive multigene panel, showed that 27.1% (112/414) had a variant in one of the genes of the mismatch repair pathway (MMR); 30.4% (126/414) had a variant in non-MMR genes such as CHEK2, APC, MUTYH, BRCA1, and BRCA2; and 42.5% (176/414) had no genetic variants. Most of the variants were found in MLH1. Pathogenic variants (PVs) in MMR genes were identified in 65.7% (96/146) of the total PVs, and 34.24% (45/146) were in non-MMR genes. Molecular and clinical characterization of patients with LS in specific populations allowed personalized follow-up, with the option for targeted treatment with immune checkpoint inhibitors and the development of public health policies. Moreover, such characterization allows for family cascade testing and consequent prevention strategies.

Transgenerational effects of gamma radiation dose and dose rate on Drosophila flies irradiated at an early embryonal stage

Ionizing radiation (IR) kills cells mainly through induction of DNA damages and the surviving cells may suffer from mutations. Transgenerational effects of IR are well documented, but the exact mechanisms underlying them are less well understood; they include induction of mutations in germ cells and epigenetic inheritance. Previously, effects in the offspring of mice and zebrafish exposed to IR have been reported. A few studies also showed indications of transgenerational effects of radiation in humans, particularly in nuclear power workers. In the present project, short- and long-term effects of low-dose-rate (LDR; 50 and 97 mGy/h) and high-dose-rate (HDR; 23.4, 47.1 and 495 Gy/h) IR in Drosophila embryos were investigated. The embryos were irradiated at different doses and dose rates and radiosensitivity at different developmental stages was investigated. Also, the survival of larvae, pupae and adults developed from embryos irradiated at an early stage (30 min after egg laying) were studied. The larval crawling and pupation height assays were applied to investigate radiation effects on larval locomotion and pupation behavior, respectively. In parallel, the offspring from 3 Gy irradiated early-stage embryos were followed up to 12 generations and abnormal phenotypes were studied. Acute exposure of embryos at different stages of development showed that the early stage embryo is the most sensitive. The effects on larval locomotion showed no significant differences between the dose rates but a significant decrease of locomotion activity above 7 Gy was observed. The results indicate that embryos exposed to the low dose rates have shorter eclosion times. At the same cumulative dose (1 up to 7 Gy), HDR is more embryotoxic than LDR. We also found a radiation-induced depigmentation on males (A5 segment of the dorsal abdomen, A5pig^-) that can be transmitted up to 12 generations. The phenomenon does not follow the classical Mendelian laws of segregation.