Search Results (291)

Background: Endometrial cancer is strongly associated with obesity, and tumors often harbor mutations in major cancer signaling pathways. To inform the integration of body composition into targeted therapy paradigms, this hypothesis-generating study explores the association between muscle mass, body fat, and tumor proteomics. Methods: We analyzed data from 113 patients in The Cancer Genome Atlas (TCGA) and Cancer Proteomic Tumor Analysis Consortium (CPTAC) cohorts and their corresponding abdominal CT scans. Among these patients, tumor proteomics data were available for 45 patients, and 133 proteins were analyzed. Adiposity and muscle components were assessed at the L3 vertebral level on the CT scans. Patients were stratified into tertiles of muscle and fat mass and categorized into three groups: high muscle/low adiposity, high muscle/high adiposity, and low muscle/all adiposities. Linear and Cox regression models were adjusted for study cohort, stage, histology type, age, race, and ethnicity. Results: Compared with the high-muscle/low-adiposity group, both the high-muscle/high-adiposity (HR = 4.3, 95% CI = 1.0–29.0) and low-muscle (HR = 4.4, 95% CI = 1.3–14.9) groups experienced higher mortality. Low muscle was associated with higher expression of phospho-4EBP1(T37 and S65), phospho-GYS(S641) and phospho-MAPK(T202/Y204) but lower expression of ARID1A, CHK2, SYK, LCK, EEF2, CYCLIN B1, and FOXO3A. High muscle/high adiposity was associated with higher expression of phospho-4EBP1 (T37), phospho-GYS (S641), CHK1, PEA15, SMAD3, BAX, DJ1, GYS, PKM2, COMPLEX II Subunit 30, and phospho-P70S6K (T389) but with lower expression of CHK2, CRAF, MSH6, TUBERIN, PR, ERK2, beta-CATENIN, AKT, and S6. Conclusions: These findings demonstrate an association between body composition and proteins involved in key cancer signaling pathways, notably the PI3K/AKT/MTOR, MAPK/ERK, cell cycle regulation, DNA damage response, and mismatch repair pathways. These findings warrant further validation and assessment in relation to prognosis and outcomes in these patients. Full article

Of all new cases of colorectal cancer, Lynch syndrome (LS) accounts for approximately 3%. This syndrome is the most common hereditary cancer syndrome and is caused by pathogenic variants in the genes responsible for DNA mismatch repair. Although the relationship between colorectal cancer risk and diet is well established, little is known regarding the influence of diet and nutritional characteristics on LS’s clinical evolution. There is some evidence suggesting that individuals living with LS should follow general guidelines for diet and alcohol restriction/moderation, so as to achieve and maintain a favorable weight status and overall health and quality of life. However, more research is needed, preferentially from clinical studies of a prospective nature with robust designs, to better inform diet and behavioral patterns targeting cancer prevention in LS. Full article

The nervous system is susceptible to DNA damage and DNA repair defects, and if DNA damage is not repaired, neuronal cells can die, causing neurodegenerative diseases in humans. The overall picture of what is known about DNA repair mechanisms in the nervous system is still unclear. The current challenge is to use the accumulated knowledge of basic science on DNA repair to improve the treatment of neurodegenerative disorders. In this review, we summarize the current understanding of the function of DNA damage repair, in particular, the base excision repair and double-strand break repair pathways as being the most important in nervous system cells. We summarize recent data on the proteins involved in DNA repair associated with neurodegenerative diseases, with particular emphasis on PARP1 and ND-associated proteins, which are involved in DNA repair and have the ability to undergo liquid–liquid phase separation. Full article

Malignant proliferating trichilemmal tumors (MPTTs), arising from the external root sheath of hair follicles, are exceptionally rare, with limited documentation of their genetic alterations. We present a case of a 64-year-old African American woman who initially presented with a gradually enlarging nodule on her posterior scalp. An initial biopsy at an outside hospital suggested metastatic adenocarcinoma or squamous cell carcinoma (SCC) of an uncertain origin. A subsequent wide local excision revealed a 2.0 cm tumor demonstrating characteristic trichilemmal keratinization, characterized by an abrupt transition from the nucleated epithelium to a laminated keratinized layer, confirming MPTT. Immunohistochemistry demonstrated diffuse p53 expression, patchy CD 34 expression, focal HER2 membranous expression, and patchy p16 staining (negative HPV ISH). A molecular analysis identified TP53 mutation and amplifications in the ERBB2 (HER2), BRD4, and TYMS. Additional gene mutations of uncertain significance included HSPH1, ATM, PDCD1 (PD-1), BARD1, MSH3, LRP1B, KMT2C (MLL3), GNA11, and RUNX1. Assessments for the homologous recombination deficiency, PD-L1 expression, gene rearrangement, altered splicing, and DNA mismatch repair gene expression were negative. The confirmation of ERBB2 (HER2) amplification in the MPTT through a molecular analysis suggests potential therapeutic avenues involving anti-HER2 monoclonal antibodies. The presence of the TP53 mutation, without the concurrent gene mutations typically observed in SCC, significantly aided in this differential diagnosis. Full article

Lynch syndrome, one of the most common genetic syndromes predisposing to cancer, is associated with a series of malignant conditions, among which the most frequent is colorectal cancer, but gynecologic cancers (especially endometrial) are also quite common. Despite the significant progress made in understanding this condition over time, there are still aspects in managing this condition that have not demonstrated clear benefits. This article aims to summarize the recommendations of international societies and present the latest developments in managing Lynch syndrome, focusing on gynecologic cancer screening and possible prevention strategies. Advances in genetic testing procedures and discoveries related to the association between oncological pathology frequency and the affected pathogenic variant type will probably lead to personalized medicine focused on the individual patient in the coming years. Although various screening methods for gynecological cancers in patients with Lynch syndrome have been used over time, they have not shown significant survival benefits. This highlights the need for studying and implementing new screening and diagnostic methods, which have been under investigation in recent years and are mentioned in this article. Full article

Many DNA metabolic pathways, including DNA repair, require the transmission of signals across long stretches of DNA or between DNA molecules. Solutions to this signaling challenge involve various mechanisms: protein factors can travel between these sites, loop DNA between sites, or form oligomers that bridge the spatial gaps. This review provides an overview of how these paradigms have been used to explain DNA mismatch repair, which involves several steps that require action-at-a-distance. Here, we describe these models in detail and how current data fit into these descriptions. We also outline regulation steps that remain unanswered in how the action is communicated across long distances along a DNA contour in DNA mismatch repair. Full article

Background: O-6-methylguanine-DNA methyltransferase is responsible for the direct repair of O6-methylguanine lesions induced by alkylating agents, including temozolomide. O-6-methylguanine-DNA methyltransferase promoter hypermethylation is a well-established biomarker for temozolomide response in glioblastoma patients, also correlated with therapeutic response in colorectal cancer. Objectives: The ARETHUSA clinical trial aims to stratify colorectal cancer patients based on their mismatch repair status. Mismatch repair-deficient patients are eligible for treatment with immune checkpoint inhibitors (anti-PDL-1), whereas mismatch repair-proficient samples are screened for O-6-methylguanine-DNA methyltransferase promoter methylation to identify those suitable for temozolomide treatment. Methods: In this context, a subset of ARETHUSA metastatic colorectal cancer samples was used to compare two different techniques for assessing O-6-methylguanine-DNA methyltransferase hypermethylation: Methyl-BEAMing, a highly sensitive digital PCR approach that combines emulsion PCR and flow cytometry, and droplet digital PCR, a more automated procedure that enables the rapid, operator-independent analysis of a large number of samples. Results: Our study clearly demonstrates that the results obtained using Methyl-BEAMing and droplet digital PCR are comparable, with both techniques showing similar accuracy, sensitivity, and reproducibility. Conclusions: Digital droplet PCR proved to be an efficient method for detecting gene promoter methylation. However, the Methyl-BEAMing method has proved more sensitive for detecting low quantities of DNA. Full article

Background: High variability in the age at cancer diagnosis in Lynch syndrome (LS) patients is widely observed, even among relatives with the same germline pathogenic variant (PV) in the mismatch repair (MMR) genes. Genetic polymorphisms and lifestyle factors are thought to contribute to this variability. We investigated the influence of previously reported genetic polymorphisms on the age at cancer diagnosis in a homogenous LS cohort with a South African founder germline PV c.1528C>T in the MLH1 gene. Methods: A total of 359 LS variant heterozygotes (LSVH) from 60 different families were genotyped for specific genetic polymorphisms in GSTM1, GSTT1, CYP1A1, CYP17, PPP2R2B, KIF20A, TGFB1, XRCC5, TNF, BCL2, CHFR, CDC25C, ATM, TTC28, CDC25C, HFE, and hTERT genes using Multiplex Polymerase Chain Reaction and MassArray methods. Kaplan–Meier survival analysis, univariate and multivariate Cox proportional hazards gamma shared frailty models adjusted for sex were used to estimate the association between age at cancer diagnosis and polymorphism genotypes. A p-value < 0.05 after correcting for multiple testing using the Benjamini–Hochberg method was considered significant at a 95% confidence interval. Results: We identified three genotypes in the cell-cycle regulation, DNA repair, and xenobiotic-metabolism genes significantly associated with age at cancer diagnosis in this cohort. The CYP1A1 rs4646903 risk (GG) and CDC25C rs3734166 polymorphic (GA+AA) genotypes were significantly associated with an increased risk of a younger age at cancer diagnosis (Adj HR: 2.03 [1.01–4.08], p = 0.034 and Adj HR: 1.53 [1.09–2.14], p = 0.015, respectively). LSVH who were heterozygous for the XRCC5 rs1051685 SNP showed significant protection against younger age at cancer diagnosis (Adj HR: 0.69 [CI, 0.48–0.99], p = 0.043). The risk of a younger age at any cancer diagnosis was significantly high in LS carriers of one to two risk genotypes (Adj HR: 1.49 [CI: 1.06–2.09], corrected p = 0.030), while having one to two protective genotypes significantly reduced the risk of developing any cancer and CRC at a younger age (Adj HR: 0.52 [CI: 0.37–0.73], and Adj HR: 0.51 [CI: 0.36–0.74], both corrected p < 0.001). Conclusions: Polymorphism genotypes in the cell-cycle regulation, DNA repair, and xenobiotic metabolizing genes may influence the age at cancer diagnosis in a homogenous LS cohort with a South African founder germline PV c.1528C>T in the MLH1 gene. Full article

Pancreatic ductal adenocarcinoma (PDAC), a leading cause of cancer mortality in the United States, presents significant treatment challenges due to its late diagnosis and poor prognosis. Despite advances, the five-year survival rates remain dismally low, with only a fraction of patients eligible for potentially curative surgical interventions. This review aims to comprehensively examine the current landscape of targeted therapies in PDAC, focusing on recent developments in precision medicine approaches. We explore various molecular targets, including KRAS mutations, DNA damage repair deficiencies, mismatch repair pathway alterations, and rare genetic fusions. The review discusses emerging therapies, such as PARP inhibitors, immune checkpoint inhibitors, and novel targeted agents, like RET and NTRK inhibitors. We analyze the results of key clinical trials and highlight the potential of these targeted approaches in specific patient subgroups. Recent developments in PDAC research have emphasized precision oncology, facilitated by next-generation sequencing and the identification of genetic and epigenetic alterations. This approach tailors treatments to individual genetic profiles, improving outcomes and reducing side effects. Significant strides have been made in classifying PDAC into various subtypes, enhancing therapeutic precision. The identification of specific mutations in genes like KRAS, along with advancements in targeted therapies, including small molecule inhibitors, offers new hope. Furthermore, emerging therapies targeting DNA repair pathways and immunotherapeutic strategies also show promising results. As research evolves, integrating these targeted therapies with conventional treatments might improve survival rates and quality of life for PDAC patients, underscoring the shift towards a more personalized treatment paradigm. Full article

Background: The effect of gender dimorphism and marital status on colorectal cancer mortality have been previously documented, but the relationship between these factors and DNA mismatch repair protein (MMRP) expression status is unknown. Methods: Colectomy specimens were reviewed retrospectively for patients between 2018 and 2023, with demographics including race/ethnicity, gender, marital status, faith, body mass index, pathologic staging, and MMRP expression status. Statistical analyses were performed by using baseline characteristics tables and various programs in the R package. Results: A total 1018 colectomies were reviewed, and the tumor stages were significantly higher in the right colon (stage 3 and 4) than in the left colon and rectosigmoid colon (p < 0.01). Marital status was significantly associated with patients’ gender, age, tumor size, and tumor stages (all p < 0.01). MMRP status was available in 775 cases, with 139 (17.9%) MMRP-deficient and 636 (82%) MMRP-proficient. MMRP deficiency was significantly associated with older female patients, larger tumor sizes, higher tumor stages, higher histologic grades, and was more common in the right colon (all p < 0.01). In addition, MMRP deficiency was statistically associated with a higher percentage of divorced and widowed patients (p < 0.01). Multivariate linear regression analysis revealed a persistent association of MMRP deficiency with tumor size, tumor grade, tumor stage, and nodal metastasis, but the associations with gender and marital status no longer existed. Conclusions: The differences in prevalence of CRC by gender and marital status and tumor MMRP status illustrate the importance of these factors on tumor stages and nodal metastasis but these associations are more complex with other confounding factors. Full article

Predictive biomarkers for immune checkpoint inhibitors (ICIs) in solid tumors such as melanoma, hepatocellular carcinoma (HCC), colorectal cancer (CRC), non-small cell lung cancer (NSCLC), endometrial carcinoma, renal cell carcinoma (RCC), or urothelial carcinoma (UC) include programmed cell death ligand 1 (PD-L1) expression, tumor mutational burden (TMB), defective deoxyribonucleic acid (DNA) mismatch repair (dMMR), microsatellite instability (MSI), and the tumor microenvironment (TME). Over the past decade, several types of ICIs, including cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, anti-programmed cell death 1 (PD-1) antibodies, anti-programmed cell death ligand 1 (PD-L1) antibodies, and anti-lymphocyte activation gene-3 (LAG-3) antibodies have been studied and approved by the Food and Drug Administration (FDA), with ongoing research on others. Recent studies highlight the critical role of the gut microbiome in influencing a positive therapeutic response to ICIs, emphasizing the importance of modeling factors that can maintain a healthy microbiome. However, resistance mechanisms can emerge, such as increased expression of alternative immune checkpoints, T-cell immunoglobulin (Ig), mucin domain-containing protein 3 (TIM-3), LAG-3, impaired antigen presentation, and alterations in the TME. This review aims to synthesize the data regarding the interactions between microbiota and immunotherapy (IT). Understanding these mechanisms is essential for optimizing ICI therapy and developing effective combination strategies. Full article

Breast cancer (BC) is the most frequently diagnosed cancer and the primary cause of cancer-related mortality in women. Treatment of triple-negative breast cancer (TNBC) remains particularly challenging due to its resistance to chemotherapy and poor prognosis. Extensive research efforts in BC screening and therapy have improved clinical outcomes for BC patients. Therefore, identifying reliable biomarkers for TNBC is of great clinical importance. Here, we found that tyrosine aminotransferase (TAT) expression was significantly reduced in BC and strongly correlated with the poor prognosis of BC patients, which distinguished BC patients from normal individuals, indicating that TAT is a valuable biomarker for early BC diagnosis. Mechanistically, we uncovered that methylation of the TAT promoter was significantly increased by DNA methyltransferase 3 (DNMT3A/3B). In addition, reduced TAT contributes to DNA replication and cell cycle activation by regulating homologous recombination repair and mismatch repair to ensure genomic stability, which may be one of the reasons for TNBC resistance to chemotherapy. Furthermore, we demonstrated that Diazinon increases TAT expression as an inhibitor of DNMT3A/3B and inhibits the growth of BC by blocking downstream pathways. Taken together, we revealed that TAT is silenced by DNMT3A/3B in BC, especially in TNBC, which promotes the proliferation of tumor cells by supporting DNA replication, activating cell cycle, and enhancing DNA damage repair. These results provide fresh insights and a theoretical foundation for the clinical diagnosis and treatment of BC. Full article

Overcoming temozolomide (TMZ)-resistance is a major challenge in glioblastoma therapy. Therefore, identifying the key molecular player in chemo-resistance becomes urgent. We previously reported the downregulation of PDCD10 in primary glioblastoma patients and its tumor suppressor-like function in glioblastoma cells. Here, we demonstrate that the loss of PDCD10 causes a significant TMZ-resistance during treatment and promotes a rapid regrowth of tumor cells after treatment. PDCD10 knockdown upregulated MGMT, a key enzyme mediating chemo-resistance in glioblastoma, accompanied by increased expression of DNA mismatch repair genes, and enabled tumor cells to evade TMZ-induced cell-cycle arrest. These findings were confirmed in independent models of PDCD10 overexpressing cells. Furthermore, PDCD10 downregulation led to the dedifferentiation of glioblastoma cells, as evidenced by increased clonogenic growth, the upregulation of glioblastoma stem cell (GSC) markers, and enhanced neurosphere formation capacity. GSCs derived from PDCD10 knockdown cells displayed stronger TMZ-resistance and regrowth potency, compared to their parental counterparts, indicating that PDCD10-induced stemness may independently contribute to tumor malignancy. These data provide evidence for a dual role of PDCD10 in tumor suppression by controlling both chemo-resistance and dedifferentiation, and highlight PDCD10 as a potential prognostic marker and target for combination therapy with TMZ in glioblastoma. Full article

A multitude of exogenous and endogenous processes have the potential to result in DNA damage. While the repair mechanisms are typically capable of correcting this damage, errors in the repair process can result in mutations. The findings of research conducted in 2012 indicate that mutations do not occur randomly but rather follow specific patterns that can be attributed to known or inferred mutational processes. The process of mutational signature analysis allows for the inference of the predominant mutational process for a given cancer sample, with significant potential for clinical applications. A deeper comprehension of these mutational signatures in CRC could facilitate enhanced prevention strategies, facilitate the comprehension of genotoxic drug activity, predict responses to personalized treatments, and, in the future, inform the development of targeted therapies in the context of precision oncology. The efforts of numerous researchers have led to the identification of several mutational signatures, which can be categorized into different mutational signature references. In CRC, distinct mutational signatures are identified as correlating with mismatch repair deficiency, polymerase mutations, and chemotherapy treatment. In this context, a mutational signature analysis offers considerable potential for enhancing minimal residual disease (MRD) tests in stage II (high-risk) and stage III CRC post-surgery, stratifying CRC based on the impacts of genetic and epigenetic alterations for precision oncology, identifying potential therapeutic vulnerabilities, and evaluating drug efficacy and guiding therapy, as illustrated in a proof-of-concept clinical trial. Full article

In clinics, chemotherapy is often combined with surgery and radiation to increase the chances of curing cancers. In the case of glioblastoma (GBM), patients are treated with a combination of radiotherapy and TMZ over several weeks. Despite its common use, the mechanism of action of the alkylating agent TMZ has not been well understood when it comes to its cytotoxic effects in tumor cells that are mostly non-dividing. The cellular response to alkylating DNA damage is operated by an intricate protein network involving multiple DNA repair pathways and numerous checkpoint proteins that are dependent on the type of DNA lesion, the cell type, and the cellular proliferation state. Among the various alkylating damages, researchers have placed a special on O⁶-methylguanine (O⁶-mG). Indeed, this lesion is efficiently removed via direct reversal by O⁶-methylguanine-DNA methyltransferase (MGMT). As the level of MGMT expression was found to be directly correlated with TMZ efficiency, O⁶-mG was identified as the critical lesion for TMZ mode of action. Initially, the mode of action of TMZ was proposed as follows: when left on the genome, O⁶-mG lesions form O6-mG: T mispairs during replication as T is preferentially mis-inserted across O⁶-mG. These O6-mG: T mispairs are recognized and tentatively repaired by a post-replicative mismatched DNA correction system (i.e., the MMR system). There are two models (futile cycle and direct signaling models) to account for the cytotoxic effects of the O⁶-mG lesions, both depending upon the functional MMR system in replicating cells. Alternatively, to explain the cytotoxic effects of alkylating agents in non-replicating cells, we have proposed a “repair accident model” whose molecular mechanism is dependent upon crosstalk between the MMR and the base excision repair (BER) systems. The accidental encounter between these two repair systems will cause the formation of cytotoxic DNA double-strand breaks (DSBs). In this review, we summarize these non-exclusive models to explain the cytotoxic effects of alkylating agents and discuss potential strategies to improve the clinical use of alkylating agents. Full article