The molecular basis of colorectal cancer (CRC) can guide patient prognosis and therapy. In Brazil, knowledge on the CRC mutation landscape is limited. Here, we investigated the mutation profile of 150 cancer-related genes by next-generation sequencing and associated with microsatellite instability (MSI) and genetic ancestry in a series of 91 Brazilian CRC patients. Driver mutations were found in the APC (71.4%), TP53 (56.0%), KRAS (52.7%), PIK3CA (15.4%) and FBXW7 (10.9%) genes. Overall, genes in the MAPK/ERK, PIK3/AKT, NOTCH and receptor tyrosine kinase signaling pathways were mutated in 68.0%, 23.1%, 16.5%, and 15.3% of patients, respectively. MSI was found in 13.3% of tumors, most of which were proximal (52.4%, P< 0.001) and had a high mutation burden. European genetic ancestry was predominant (median of 83.1%), followed by Native American (4.1%), Asian (3.4%) and African (3.2%). NF1 and BRAF mutations were associated with African ancestry, while TP53 and PIK3CA mutations were inversely correlated with Native American ancestry. Our study suggests that Brazilian CRC patients exhibit a mutation profile similar to other populations and identify the most frequently mutated genes, which could be useful in future target therapies and molecular cancer screening strategies.

DNA repair and metabolic pathways are vital to maintain cellular homeostasis in normal human cells. Both of these pathways, however, undergo extensive changes during tumorigenesis, including modifications that promote rapid growth, genetic heterogeneity, and survival. While these two areas of research have remained relatively distinct, there is growing evidence that the pathways are interdependent and intrinsically linked. Therapeutic interventions that target metabolism or DNA repair systems have entered clinical practice in recent years, highlighting the potential of targeting these pathways in cancer. Further exploration of the links between metabolic and DNA repair pathways may open new therapeutic avenues in the future. Here, we discuss the dependence of DNA repair processes upon cellular metabolism; including the production of nucleotides required for repair, the necessity of metabolic pathways for the chromatin remodeling required for DNA repair, and the ways in which metabolism itself can induce and prevent DNA damage. We will also discuss the roles of metabolic proteins in DNA repair and, conversely, how DNA repair proteins can impact upon cell metabolism. Finally, we will discuss how further research may open therapeutic avenues in the treatment of cancer.

DNA repair pathways are essential to maintain the integrity of the genome and prevent cell death and tumourigenesis. Here, we show that the Barrier-to-Autointegration Factor (Banf1) protein has a role in the repair of DNA double-strand breaks. Banf1 is characterized as a nuclear envelope protein and mutations in Banf1 are associated with the severe premature aging syndrome, Néstor–Guillermo Progeria Syndrome. We have previously shown that Banf1 directly regulates the activity of PARP1 in the repair of oxidative DNA lesions. Here, we show that Banf1 also has a role in modulating DNA double-strand break repair through regulation of the DNA-dependent Protein Kinase catalytic subunit, DNA-PKcs. Specifically, we demonstrate that Banf1 relocalizes from the nuclear envelope to sites of DNA double-strand breaks. We also show that Banf1 can bind to and directly inhibit the activity of DNA-PKcs. Supporting this, cellular depletion of Banf1 leads to an increase in non-homologous end-joining and a decrease in homologous recombination, which our data suggest is likely due to unrestrained DNA-PKcs activity. Overall, this study identifies how Banf1 regulates double-strand break repair pathway choice by modulating DNA-PKcs activity to control genome stability within the cell.

No abstract

Background: Colorectal cancer (CRC) is the third most common cancer in Brazil, where it appears as the fifth most deadly cancer. Brazilian National Cancer Institute estimates for the year of 2016 in Brazil 16,660 newly diagnosed cases of CRC in men and 17,620 in women. There is evidence that the incidence and mortality rates can be reduced through the detection of precursor lesions and early cancer in the context of CRC screening. Aberrant hypermethylation of cancer-related genes has emerged as a promising strategy for the molecular CRC screening. However, the methylation profile of colorectal cancer of the Brazilian population has limited information about its characterization and frequency. Objective: To investigate the frequency of DNA methylation in the promoter region of tumor suppressor genes SEPT9, NDRG4, and CDKN2A (p16) in sporadic CRCs of Brazilian patients. Methods: Retrospective molecular analysis included 57 adult patients with CRC in different clinical stages attended at the Barretos Cancer Hospital. Demographic, clinical, and tumor-related characteristics were obtained from medical records. DNA was extracted from fresh-frozen tumor tissues. Levels of DNA methylation were determined by quantitative pyrosequencing. Results: The mean ± SD age of the 57 patients' analysis was 64.40 ±14 years; 56.14% (32/57) were males. Almost all tumors (56/57; 98.24%) were located in the left side of the colon, from descending colon to rectum. Regarding stage, 3/57 (5.26%) were stage 0, 15/57 (26.31 %) stage I, 27/57 (47.36%) stage II, 10/57 (17.54%) stage III, and 2/57 (3.53%) stage IV tumors. Among 57 analyzed, 52/57 (91.22%) were methylated for SEPT9, 42/57 (73.68%) for NDRG4, and 15/57 (26.31%) for CDKN2A. In conclusion, in our Brazilian case series, the gene SEPT9 and NDGR4 showed high frequency of methylation CRC tissues, similar with results found in other populations. Citation Format: Thais Sobanski, Lidia Arantes, Wellington dos Santos, Ronilson Durães, Marcus Matsushita, Rui Manuel Reis, Denise Peixoto Guimaraes. Methylation profile of SEPT9, NDRG4, p16 genes in colorectal cancer [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A17.

Pregnant people infected with the SARS-CoV-2 virus have shown a higher incidence of "preeclampsia-like syndrome". Preeclampsia is a systematic syndrome that affects 5% of people worldwide and is the leading cause of maternal mortality. It is characterised by placental dysfunction, leading to poor placental perfusion, maternal hypertension and neurological disturbances. Here, we used whole-transcriptome, spatial profiling of placental tissues to analyse the expression of genes between placentae from pregnant participants who contracted SARS-CoV-2 and those prior to the pandemic. Our analysis of the trophoblast and villous core stromal cell populations revealed tissue-specific pathways enriched in the SARS-CoV-2 placentae that align with a pre-eclampsia signature. Most notably, we found enrichment of pathways involved in vascular tension, blood pressure, inflammation, and oxidative stress. This study illustrates how spatially resolved transcriptomic analysis can aid in understanding the underlying pathogenic mechanisms of SARS-CoV-2 in pregnancy that are thought to induce "preeclampsia-like syndrome". Our study highlights the benefits of spatial profiling to map the crosstalk between trophoblast and villous core stromal cells linked to pathways involved in "preeclampsia-like syndrome."

No abstract

Introduction: Metabolic reprogramming, known as the Warburg effect, is one of the universal differences between cancer cells and non-cancerous cells. Glucose metabolism and DNA repair are frequently dysregulated in cancer. Metabolic pathways provide cells with nucleic acids and energy required to repair DNA. However, the underlying mechanisms that promote crosstalk between these processes are unknown. ALDOA is a glycolytic enzyme that catalyses the conversion of fructose 1,6-bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. ALDOA is overexpressed in several types of cancer. In this study, we demonstrate a novel mechanism through which ALDOA directly regulates DSB repair. Methods: ALDOA was depleted from cells using siRNA and single-shot quantitative proteomics were performed. Immunofluorescence was utilized to determine the localization of ALDOA. DSB repair reporter assays were used to measure DSB break repair. Gene expression was quantified by western blot and qPCR. Immunoprecipitations were used to detect protein:protein interactions. Statistical analysis: The experiments were at least n=3, and data are presented as the means ± SEM. Statistical significance was evaluated using Student’s t-test or one-way ANOVA. Results: In order to identify ALDOA-dependent pathways, we performed quantitative mass spectrometry on ALDOA depleted cells. In addition to the expected decrease in glycolysis pathways, we also observed a significant downregulation of DNA repair proteins in ALDOA depleted cells. Further analysis showed that the ALDOA protein responds to DNA damage (IR) and migrates from the cytosol to the nucleus, suggesting that it could be directly involved in DNA damage repair. Slower clearance of γ-H2AX foci (a DSB marker), and decreased clonogenicity following irradiation (IR) treatment were also observed, indicating dysfunctional DNA repair processes. Repair of DSBs is primarily though the NHEJ (non-homologous end-joining) or HR (homologous recombination) -mediated DNA repair pathways. Silencing ALDOA led to a decrease in both NHEJ- and HR-mediated DSB repair efficiency. This disruption was likely due to the significant reduction of both the mRNA and protein of the DNA repair effector kinases, DNA-Dependent Kinase (DNA-PK) and Ataxia and Telangiectasia Mutated (ATM) in ALDOA-depleted cells. In addition to regulating the expression of DNAPK and ATM we also found that ALDOA directly interacted with both kinases, suggesting that it may have a direct role in regulating their function. Here, we define a role for ALDOA in the repair of DNA DSBs, through the regulation of DNA repair effector kinase expression and function. Conclusion: These results identify crosstalk between metabolic and DNA repair pathways and have implications for cancer treatment and tumorigenesis. The role of ALDOA in DNA repair could promote therapeutic resistance in tumors and may be a future therapeutic target to sensitize tumors to DNA-damaging agents such as radiation. Citation Format: Amila Suraweera, Kenneth O’Byrne, Derek Richard, Emma Bolderson, Thais Sobanski. Aldolase A (ALDOA) is required for efficient DNA double-strand break (DSB) repair [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-031.