Extensive Expression of the Virulome Related to Antibiotic Genotyping in Nosocomial Strains of Klebsiella pneumoniae.

The emergence of hyper-virulent and multidrug-resistant (MDR) strains of Klebsiella pneumoniae isolated from patients with hospital- and community-acquired infections is a serious health problem that increases mortality. The molecular analysis of virulome expression related to antimicrobial-resistant genotype and infection type in K. pneumoniae strains isolated from patients with hospital- and community-acquired infections has been poorly studied. In this study, we analyzed the overall expression of the virulence genotype associated with the antimicrobial resistance genotype and pulse field gel electrophoresis (PFGE) type (PFtype) in K. pneumoniae. We studied 25 strains of K. pneumoniae isolated from patients who developed bacteremia and pneumonia during their hospital stay and 125 strains from outpatients who acquired community-acquired infections. Susceptibility to 12 antimicrobials was determined by Kirby-Bauer. The identification of K. pneumoniae and antibiotic-resistance genes was performed using polymerase chain reaction (PCR). To promote the expression of the virulence genes of K. pneumoniae, an in vitro infection model was used in human epithelial cell lines A549 and A431. Bacterial RNA was extracted with the QIAcube robotic workstation, and reverse transcription to cDNA was performed with the Reverse Transcription QuantiTect kit (Qiagen). The determination of the expression of the virulence genes was performed by real-time PCR. In addition, 57.3% (n = 86) of the strains isolated from patients with hospital- and community-acquired infections were multidrug-resistant (MDR), mainly to beta-lactam antibiotics (CB, AM, CFX, and CF), aminoglycosides (GE), quinolones (CPF and NOF), nitrofurantoin (NF), and sulfamethoxazole/trimethoprim (SXT). The most frequently expressed genes among strains isolated from hospital- and community-acquired infections were adhesion-type, ycfm (80%), mrkD (51.3%), and fimH (30.7%); iron uptake, irp2 (84%), fyuA (68.7%), entB (64.7%), and irp1 (56.7%); and protectins, rpmA (26%), which were related to antibiotic-resistance genes, blaTEM (96%), blaSHV (64%), blaCITM (52.6%), blaCTXM-1 (44.7%), tetA (74%), sul1 (57.3%), aac(3)-IV (40.7%), and aadA1 (36%). The results showed the existence of different patterns of expression of virulome related to the genotype of resistance to antimicrobials and to the PFtypes in the strains of K. pneumoniae that cause hospital- and community-acquired infections. These findings are important and may contribute to improving medical treatment strategies against infections caused by K. pneumoniae.

Mutational spectrum of breast cancer by shallow whole-genome sequencing of cfDNA and tumor gene panel analysis.

Breast cancer (BC) has different molecular subgroups related to different risks and treatments. Tumor biopsies for BC detection are invasive and may not reflect tumor heterogeneity. Liquid biopsies have become relevant because they might overcome these limitations. We rationalize that liquid cfDNA biopsies through shallow whole genome sequencing (sWGS) could improve the detection of tumor alterations, complementing the genomic profiling. We evaluated the feasibility to detect somatic copy number alterations (SCNAs) in BC using shallow whole genome sequencing (sWGS) in cfDNA from archived samples from National Cancer Institute of Colombia patients. We sequenced tumor tissues from 38 BC patients with different molecular subtypes using a gene panel of 176 genes significantly mutated in cancer, and by liquid biopsies using sWGS on 20 paired samples to detect SCNAs and compare with the tumor samples. We identified an extensive intertumoral heterogeneity between the molecular subtypes of BC, with a mean tumor load of 602 mutations in the gene panel of tumor tissues. There was a 12.3% of concordance in deletions in the cfDNA-tumor pairs considering only the genes covered by the panel encompassing seven genes: BRCA1, CDK12, NF1, MAP2K4, NCOR1, TP53, and KEAP1 in three patients. This study shows the feasibility to complement the genomic analysis of tumor tissue biopsies to detect SCNA in BC using sWGS in cfDNA, providing a wider identification of potential therapeutic targets.

Methylation marks in blood DNA reveal breast cancer risk in patients fulfilling hereditary disease criteria.

Less than 15-20% of patients who meet the criteria for hereditary breast and ovarian cancer (HBOC) carry pathogenic coding genetic mutations, implying that other molecular mechanisms may contribute to the increased risk of this condition. DNA methylation in peripheral blood has been suggested as a potential epigenetic marker for the risk of breast cancer (BC). We aimed to discover methylation marks in peripheral blood associated with BC in 231 pre-treatment BC patients meeting HBOC criteria, testing negative for coding pathogenic variants, and 156 healthy controls, through methylation analysis by targeted bisulfite sequencing on 18 tumor suppressor gene promoters (330 CpG sites). We found i) hypermethylation in EPCAM (17 CpG sites; p = 0.017) and RAD51C (27 CpG sites; p = 0.048); ii) hypermethylation in 36 CpG-specific sites (FDR q < 0.05) in the BC patients; iii) four specific CpG sites were associated with a higher risk of BC (FDR q < 0.01, Bonferroni p < 0.001): cg89786999-FANCI (OR = 1.65; 95% CI:1.2-2.2), cg23652916-PALB2 (OR = 2.83; 95% CI:1.7-4.7), cg47630224-MSH2 (OR = 4.17; 95% CI:2.1-8.5), and cg47596828-EPCAM (OR = 1.84; 95% CI:1.5-2.3). Validation of cg47630224-MSH2 methylation in one Australian cohort showed an association with 3-fold increased BC risk (AUC: 0.929; 95% CI: 0.904-0.955). Our findings suggest that four DNA methylation CpG sites may be associated with a higher risk of BC, potentially serving as biomarkers in patients without detectable coding mutations.

Evaluation of genetic alterations in hereditary cancer susceptibility genes in the Ashkenazi Jewish women community of Mexico.

Background: Individuals of Ashkenazi Jewish ancestry have been identified as having higher prevalence of specific pathogenic variants associated with susceptibility to specific rare and chronic diseases. In Mexico, the prevalence and composition of rare cancer predisposing germline variants in Ashkenazi Jewish individuals has not been evaluated. Aim and methods: We aimed to evaluate the prevalence of pathogenic variants by massive parallel sequencing in a panel of 143 cancer-predisposing genes in 341 women from the Ashkenazi Jewish community of Mexico, who were contacted and invited to participate in the study through the ALMA Foundation for Cancer Reconstruction. Pre- and posttest genetic counseling was given and a questionnaire on personal, gyneco-obstetric, demographic and lifestyle variables was conducted. From peripheral blood DNA, the complete coding region, and splicing sites of a panel of 143 cancer susceptibility genes, including 21 clinically relevant genes, were sequenced. The Mexican founder mutation BRCA1 ex9-12del [NC_000017.10(NM_007294):c. (825+1-826-1)_(4,589+1-4,590-1)del] was also evaluated. Results: Among study participants (mean age ±standard deviation: 47 ± 14) 15% reported a personal history of cancer (50/341). Fourteen percent of participants (48/341) were carriers of pathogenic and likely pathogenic variants distributed among seven high-risk genes (APC, CHEK2, MSH2, BMPR1A, MEN1, MLH1, and MSH6), whereas 18.2% (62/341) had variants of uncertain clinical significance in genes associated with breast and ovarian cancer susceptibility (list of genes with VUS). Pathogenic and likely pathogenic variants in 16 susceptibility genes with ambiguous or non-well-established risk association for cancer were detected in 17.6% (60/341) of participants. Sixty four percent of participants reported current alcohol consumption compared with the 39 percent prevalence of alcohol consumption in Mexican women. None of the participants carried the recurrent Ashkenazi and Mexican founder mutations in BRCA1 or BRCA2, but 2% (7/341) had pathogenic Ashkenazi Jewish founder variants in BLM. Conclusion: Our findings show a diverse pathogenic variant composition among the recruited individuals of Ashkenazi Jewish ancestry in Mexico consistent with being a high-risk population for genetic diseases, which warrants further investigation to adequately assess the burden of hereditary breast cancer in this group and implement appropriate preventative programs.

Molecular transition of SARS-CoV-2 from critical patients during the first year of the COVID-19 pandemic in Mexico City.

Background: The SARS-CoV-2 virus has caused unprecedented mortality since its emergence in late 2019. The continuous evolution of the viral genome through the concerted action of mutational forces has produced distinct variants that became dominant, challenging human immunity and vaccine development. Aim and methods: In this work, through an integrative genomic approach, we describe the molecular transition of SARS-CoV-2 by analyzing the viral whole genome sequences from 50 critical COVID-19 patients recruited during the first year of the pandemic in Mexico City. Results: Our results revealed differential levels of the evolutionary forces across the genome and specific mutational processes that have shaped the first two epidemiological waves of the pandemic in Mexico. Through phylogenetic analyses, we observed a genomic transition in the circulating SARS-CoV-2 genomes from several lineages prevalent in the first wave to a dominance of the B.1.1.519 variant (defined by T478K, P681H, and T732A mutations in the spike protein) in the second wave. Conclusion: This work contributes to a better understanding of the evolutionary dynamics and selective pressures that act at the genomic level, the prediction of more accurate variants of clinical significance, and a better comprehension of the molecular mechanisms driving the evolution of SARS-CoV-2 to improve vaccine and drug development.

Early detection of colorectal cancer somatic mutations using cfDNA liquid biopsies in a murine carcinogenesis model.

Colorectal cancer (CRC) is one of the top five cancers in incidence and mortality worldwide. The early detection of this neoplasm through analysis of circulating free DNA (cfDNA), which carries tumor genetic alterations, as a liquid biopsy, could have a major impact in enhancing early detection and reducing the mortality rate. The aim of this work was to demonstrate the feasibility of using cfDNA as a liquid biopsy for the early detection of CRC. For this purpose, we implemented an azoxymethane and dextran sodium sulfate-induced murine carcinogenesis model to detect oncogenic somatic mutations in Ctnnb1 and Kras during CRC development. To enhance the sensitivity in the detection, E-ice-COLD-PCR was utilized to selectively enrich for mutant alleles, followed by massively parallel sequencing. Driving somatic mutations were detected in Ctnnb1 and Kras in the liquid biopsies of early stages of tumor development, corresponding to the formation of aberrant crypt foci, the first histological alterations that can be identified throughout the formation of CRC. The concentration of cfDNA was increased along the carcinogenic process. Polyclonality in Ctnnb1 was found in tumor samples and cfDNA in this model. On the other hand, the use of cfDNA as a non-invasive test resulted in superior early detection compared to microPET/CT imaging. As a proof-of-principle, this study shows the great potential use of allelic-specific PCR for the detection and enrichment of pathogenic alleles present in cfDNA samples, as a test for early non-invasive detection of CRC. This work provides scientific evidence to set methodological bases that allow early detection of mutations in cfDNA obtained from plasma of CRC in humans.

Cis-Acting Factors Causing Secondary Epimutations: Impact on the Risk for Cancer and Other Diseases.

Epigenetics affects gene expression and contributes to disease development by alterations known as epimutations. Hypermethylation that results in transcriptional silencing of tumor suppressor genes has been described in patients with hereditary cancers and without pathogenic variants in the coding region of cancer susceptibility genes. Although somatic promoter hypermethylation of these genes can occur in later stages of the carcinogenic process, constitutional methylation can be a crucial event during the first steps of tumorigenesis, accelerating tumor development. Primary epimutations originate independently of changes in the DNA sequence, while secondary epimutations are a consequence of a mutation in a cis or trans-acting factor. Secondary epimutations have a genetic basis in cis of the promoter regions of genes involved in familial cancers. This highlights epimutations as a novel carcinogenic mechanism whose contribution to human diseases is underestimated by the scarcity of the variants described. In this review, we provide an overview of secondary epimutations and present evidence of their impact on cancer. We propose the necessity for genetic screening of loci associated with secondary epimutations in familial cancer as part of prevention programs to improve molecular diagnosis, secondary prevention, and reduce the mortality of these diseases.

The Evolution of Clinically Aggressive Triple-Negative Breast Cancer Shows a Large Mutational Diversity and Early Metastasis to Lymph Nodes.

In triple-negative breast cancer (TNBC), only 30% of patients treated with neoadjuvant chemotherapy achieve a pathological complete response after treatment and more than 90% die due to metastasis formation. The diverse clinical responses and metastatic developments are attributed to extensive intrapatient genetic heterogeneity and tumor evolution acting on this neoplasm. In this work, we aimed to evaluate genomic alterations and tumor evolution in TNBC patients with aggressive disease. We sequenced the whole exome of 16 lesions from four patients who did not respond to therapy, and took several follow-up samples, including samples from tumors before and after treatment, as well as from the lymph nodes and skin metastases. We found substantial intrapatient genetic heterogeneity, with a variable tumor mutational composition. Early truncal events were MCL1 amplifications. Metastatic lesions had deletions in RB1 and PTEN, along with TERT, AKT2, and CCNE1 amplifications. Mutational signatures 06 and 12 were mainly detected in skin metastases and lymph nodes. According to phylogenetic analysis, the lymph node metastases occurred at an early stage of TNBC development. Finally, each patient had three to eight candidate driving mutations for targeted treatments. This study delves into the genomic complexity and the phylogenetic and evolutionary development of aggressive TNBC, supporting early metastatic development, and identifies specific genetic alterations associated with a response to targeted therapies.

Comprehensive Genomic Profile of Heterogeneous Long Follow-Up Triple-Negative Breast Cancer and Its Clinical Characteristics Shows DNA Repair Deficiency Has Better Prognostic.

Triple-negative breast cancer (TNBC) presents a marked diversity at the molecular level, which promotes a clinical heterogeneity that further complicates treatment. We performed a detailed whole exome sequencing profile of 29 Mexican patients with long follow-up TNBC to identify genomic alterations associated with overall survival (OS), disease-free survival (DFS), and pathologic complete response (PCR), with the aim to define their role as molecular predictive factors of treatment response and prognosis. We detected 31 driver genes with pathogenic mutations in TP53 (53%), BRCA1/2 (27%), CDKN1B (9%), PIK3CA (9%), and PTEN (9%), and 16 operative mutational signatures. Moreover, tumors with mutations in BRCA1/2 showed a trend of sensitivity to platinum salts. We found an association between deficiency in DNA repair and surveillance genes and DFS. Across all analyzed tumors we consistently found a heterogeneous molecular complexity in terms of allelic composition and operative mutational processes, which hampered the definition of molecular traits with clinical utility. This work contributes to the elucidation of the global molecular alterations of TNBC by providing accurate genomic data that may help forthcoming studies to improve treatment and survival. This is the first study that integrates genomic alterations with a long follow-up of clinical variables in a Latin American population that is an underrepresented ethnicity in most of the genomic studies.

Influence of Genetic and Non-Genetic Risk Factors for Serum Uric Acid Levels and Hyperuricemia in Mexicans.

Risk of hyperuricemia is modified by genetic and environmental factors. Our aim was to identify factors associated with serum uric acid levels and hyperuricemia in Mexicans. A pilot Genome-wide association study GWAS was performed in a subgroup of participants (n = 411) from the Health Workers Cohort Study (HWCS). Single nucleotide polymorphisms (SNPs) associated with serum uric acid levels were validated in all the HWCS participants (n = 1939) and replicated in independent children (n = 1080) and adult (n = 1073) case-control studies. The meta-analysis of the whole HWCS and replication samples identified three SLC2A9 SNPs: rs1014290 (p = 2.3 × 10-64), rs3775948 (p = 8.2 × 10-64) and rs11722228 (p = 1.1 × 10-17); and an ABCG2 missense SNP, rs2231142 (p = 1.0 × 10-18). Among the non-genetic factors identified, the visceral adiposity index, smoking, the metabolic syndrome and its components (waist circumference, blood pressure, glucose and hyperlipidemia) were associated with increased serum uric acid levels and hyperuricemia (p < 0.05). Among the female HWCS participants, the odds ratio for hyperuricemia was 1.24 (95% CI, 1.01-1.53) per unit increase in soft drink consumption. As reported in other studies, our findings indicate that diet, adiposity and genetic variation contribute to the elevated prevalence of hyperuricemia in Mexico.

Serum Proteomic Analysis Reveals Vitamin D-Binding Protein (VDBP) as a Potential Biomarker for Low Bone Mineral Density in Mexican Postmenopausal Women.

Osteoporosis is a skeletal disease mainly affecting women over 50 years old and it represents a serious public health problem because of the high socioeconomic burden. This disease is characterized by deterioration of bone microarchitecture, low bone mineral density (BMD), and increased risk of fragility fractures. This study aimed to identify serum useful proteins as biomarkers for the diagnosis and/or prognosis of osteoporosis and fracture risk. We collected 446 serum samples from postmenopausal women aged ≥45 years old. Based on the BMD measurement, we classified the participants into three groups: osteoporotic, osteopenic, and normal. In an initial discovery stage, we conducted a proteomic approach using two-dimensional differential gel electrophoresis (2D-DIGE). The peptides into the spots of interest were identified through matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF/TOF). Enzyme-linked immunosorbent assay (ELISA) was performed to validate the proteins of interest. We identified 27 spots of interest when comparing low BMD versus normal BMD postmenopausal women. Based on their relevance in bone metabolism, we analyzed three proteins: ceruloplasmin (CP), gelsolin (GSN), and vitamin D-binding protein (VDBP). Our results demonstrated that low serum VDBP levels correlate with low BMD (osteopenic and osteoporotic). Therefore, VDBP could be considered as a novel, potential, and non-invasive biomarker for the early detection of osteoporosis.

Identification of miR-708-5p in peripheral blood monocytes: Potential marker for postmenopausal osteoporosis in Mexican-Mestizo population.

IMPACT STATEMENT: This is the first study in which hsa-miR-708-5p has been identified in peripheral blood monocytes (osteoclast precursors) and associated with postmenopausal osteoporosis through small RNA-Sequencing, in an Admixed Mexican Mestizo population. By conducting in silico and bioinformatic analyzes, we identified target genes and important signaling pathways involved in bone metabolism pointing hsa-miR-708-5p as a candidate marker for osteoporosis in Mexican population. These approaches provide a landscape of the post-transcriptional regulation, which can be useful for the management of postmenopausal osteoporosis along with the potential use of microRNAs as markers for its early detection.