DNA methylation patterns suggest the involvement of DNMT3B and TET1 in osteosarcoma development.

DNA methylation may be involved in the development of osteosarcomas. Osteosarcomas commonly arise during the bone growth and remodeling in puberty, making it plausible to infer the involvement of epigenetic alterations in their development. As a highly studied epigenetic mechanism, we investigated DNA methylation and related genetic variants in 28 primary osteosarcomas aiming to identify deregulated driver alterations. Methylation and genomic data were obtained using the Illumina HM450K beadchips and the TruSight One sequencing panel, respectively. Aberrant DNA methylation was spread throughout the osteosarcomas genomes. We identified 3146 differentially methylated CpGs comparing osteosarcomas and bone tissue samples, with high methylation heterogeneity, global hypomethylation and focal hypermethylation at CpG islands. Differentially methylated regions (DMR) were detected in 585 loci (319 hypomethylated and 266 hypermethylated), mapped to the promoter regions of 350 genes. These DMR genes were enriched for biological processes related to skeletal system morphogenesis, proliferation, inflammatory response, and signal transduction. Both methylation and expression data were validated in independent groups of cases. Six tumor suppressor genes harbored deletions or promoter hypermethylation (DLEC1, GJB2, HIC1, MIR149, PAX6, and WNT5A), and four oncogenes presented gains or hypomethylation (ASPSCR1, NOTCH4, PRDM16, and RUNX3). Our analysis also revealed hypomethylation at 6p22, a region that contains several histone genes. Copy-number changes in DNMT3B (gain) and TET1 (loss), as well as overexpression of DNMT3B in osteosarcomas provide a possible explanation for the observed phenotype of CpG island hypermethylation. While the detected open-sea hypomethylation likely contributes to the well-known osteosarcoma genomic instability, enriched CpG island hypermethylation suggests an underlying mechanism possibly driven by overexpression of DNMT3B likely resulting in silencing of tumor suppressors and DNA repair genes.

Absolute telomere length in peripheral blood lymphocytes of workers exposed to construction environment.

Construction environment is composed of various substances classified as carcinogens. Thus, workers exposed in this environment can be susceptible to genomic instability that can be evaluated by absolute telomere length (TL). In this work, we evaluated TL in construction workers compared to a non-exposed group performed by qPCR assay. The TL was evaluated in 59 men exposed to the construction environment (10 years of exposure) and 49 men non-exposed. Our data showed that individuals exposed to the construction environment exhibited a significantly lower TL in relation to non-exposed group (p = 0.009). Also, on the multiple linear regression model, we observed that TL was significantly influenced by the construction environment exposure (p ≤ 0.001). Additionally, the arsenic exposure is associated to a shortening telomere (p ≤ 0.001), and the lead exposure caused an increase in TL (p ≤ 0.001). Thus, our findings suggest a modulation in TL by construction environment exposure, mainly by arsenic and lead exposure.

Hotspot TERT promoter mutations are rare events in testicular germ cell tumors.

The abnormal activation of telomerase, codified by the telomerase reverse transcriptase (TERT) gene, is related to one of cancer hallmarks. Hotspot somatic mutations in the promoter region of TERT, specifically the c.-124:C>T and c.-146:C>T, were recently identified in a range of human cancers and have been associated with a more aggressive behavior. Testicular germ cell tumors frequently exhibit a good prognosis; however, the development of refractory disease is still a clinical challenge. In this study, we aim to evaluate for the first time the presence of the hotspot telomerase reverse transcriptase gene promoter mutations in testicular germ cell tumors. A series of 150 testicular germ cell tumor cases and four germ cell tumor cell lines were evaluated by PCR followed by direct Sanger sequencing and correlated with patient's clinical pathological features. Additionally, we genotyped the telomerase reverse transcriptase gene promoter single nucleotide polymorphism rs2853669 (T>C) located at -245 position. We observed the presence of the TERT promoter mutation in four patients, one exhibited the c.-124:C>T and three the c.-146:C>T. No association between TERT mutation status and clinicopathological features could be identified. The analysis of the rs2853669 showed that variant C was present in 22.8 % of the cases. In conclusion, we showed for the first time that TERT promoter mutations occur in a small subset (~3 %) of testicular germ cell tumors.

Lipidomics by Nuclear Magnetic Resonance Spectroscopy and Liquid Chromatography-High-Resolution Mass Spectrometry in Osteosarcoma: A Pilot Study.

Cancer is a complex disease that can also affect the younger population; however, it is responsible for a relatively high mortality rate of children and youth, especially in low- and middle-income countries (LMICs). Besides that, lipidomic studies in this age range are scarce. Therefore, we analyzed blood serum samples from young patients (12 to 35 years) with bone sarcoma (osteosarcoma) and compared their lipidomics to the ones from the control group of samples, named healthy control (HC group), using NMR and LC-MS techniques. Furthermore, differences in the lipidomic profiles between OS patients with and without metastasis indicate higher glycerophosphocholine (GPC) and glycerophospholipid (GPL) levels in osteosarcoma and increased cholesterol, choline, polyunsaturated fatty acids (PUFAs), and glycerols during the metastasis. These differences, detected in the peripheral blood, could be used as biomarkers for liquid biopsy.

Comprehensive microRNA expression analysis of pediatric gonadal germ cell tumors: unveiling novel biomarkers and signatures.

microRNAs (miRNAs) are small endogenous noncoding RNAs, and alterations in their expression may contribute to oncogenesis. Discovering a unique miRNA pattern holds the potential for early detection and novel treatment possibilities in cancer. This study aimed to evaluate miRNA expression in pediatric patients with gonadal germ cell tumors (GCTs), focusing on characterizing the miRNA profiles of each histological subtype and identifying a distinct histological miRNA signature for a total of 42 samples of pediatric gonadal GCTs. The analysis revealed distinct miRNA expression profiles for all histological types, regardless of the primary site. We identified specific miRNA expression signatures for each histological type, including 34 miRNAs for dysgerminomas, 13 for embryonal carcinomas, 25 for yolk sac tumors, and one for immature teratoma, compared to healthy controls. Furthermore, we identified 26 miRNAs that were commonly expressed in malignant tumors, with six miRNAs (miR-302a-3p, miR-302b-3p, miR-371a-5p, miR-372-3p, miR-373-3p, and miR-367-3p) showing significant overexpression. Notably, miR-302b-3p exhibited a significant association with all the evaluated clinical features. Our findings suggest that miRNAs have the potential to aid in the diagnosis, prognosis, and management of patients with malignant GCTs.

MicroRNA­130a­3p inhibition suppresses cervical cancer cell progression.

MicroRNAs (miRNAs or miRs) play essential roles in the initiation and progression of human tumors, including cervical cancer. However, the mechanisms underlying their actions in cervical cancer remain unclear. The present study aimed to evaluate the functional role of miR­130a­3p in cervical cancer. Cervical cancer cells were transfected with a miRNA inhibitor (anti­miR­130a­3p) and a negative control. Adhesion­independent cell proliferation, migration and invasion were evaluated. The findings presented herein demonstrated that miR­130a­3p was overexpressed in HeLa, SiHa, CaSki, C­4I and HCB­514 cervical cancer cells. The inhibition of miR­130a­3p significantly reduced the proliferation, migration and invasion of cervical cancer cells. The canonical delta­like Notch1 ligand (DLL1) was identified as a possible direct target of miR­103a­3p. The DLL1 gene was further found to be significantly downregulated in cervical cancer tissues. On the whole, the present study demonstrates that miR­130a­3p contributes to the proliferation, migration and invasion of cervical cancer cells. Therefore, miR­130a­3p may be used as a biomarker to determine cervical cancer progression.

RAD50 Deficient in a Breast Cancer Model Predicts Sensitivity to PARP Inhibitors.

BACKGROUND: Breast and ovarian tumors with pathogenic variants in BRCA1 or BRCA2 genes are more sensitive to poly (ADP-ribose) polymerase inhibitors (PARPi) treatment than wildtype tumors. Pathogenic variants in non-BRCA1/2 homologous recombination repair genes (HRR) also concede sensitivity to PARPi treatment. RAD50 participates in the Mre11-RAD50-Nbn (MRN) complex of the HRR pathway and plays an important role in DNA repair. OBJECTIVE: The objective of this study is to evaluate whether RAD50 protein deficiency modulates the PARPi response in breast cancer cell lines. METHODS: T47D breast cancer cell line was modified using small interfering RNA and CRISPR/Cas9 technology, to knockout the RAD50 gene. PARPi response (niraparib, olaparib and rucaparib alone or in combination with carboplatin), in T47D and T47D-edited clones, was evaluated by cell viability, cell cycle, apoptosis and protein expression analyses. RESULTS: Treatment with niraparib and carboplatin exerted a synergistic effect on T47D-RAD50 deficient cells and an antagonistic effect on T47D cells parental. Cell cycle analysis demonstrated an increase in the G2/M population in cells treated with niraparib or rucaparib alone or in combination with carboplatin. T47D-RAD50 deficient cells treated with rucaparib and carboplatin exhibited twofold levels in late apoptosis, also showing differences in PARP activation. All T47D RAD50 deficient clones treated with niraparib or rucaparib combined with carboplatin, or rucaparib alone showed increased levels of H2AX phosphorylation. CONCLUSIONS: T47D RAD50 deficient cells treated with PARP inhibitors alone or in combination with carboplatin showed cell cycle arrest in the G2/M phase, leading to death by apoptosis. Thus, RAD50 deficiency may be a good biomarker for predicting PARPi response.

Comprehensive Molecular Landscape of Cetuximab Resistance in Head and Neck Cancer Cell Lines.

Cetuximab is the sole anti-EGFR monoclonal antibody that is FDA approved to treat head and neck squamous cell carcinoma (HNSCC). However, no predictive biomarkers of cetuximab response are known for HNSCC. Herein, we address the molecular mechanisms underlying cetuximab resistance in an in vitro model. We established a cetuximab resistant model (FaDu), using increased cetuximab concentrations for more than eight months. The resistance and parental cells were evaluated for cell viability and functional assays. Protein expression was analyzed by Western blot and human cell surface panel by lyoplate. The mutational profile and copy number alterations (CNA) were analyzed using whole-exome sequencing (WES) and the NanoString platform. FaDu resistant clones exhibited at least two-fold higher IC50 compared to the parental cell line. WES showed relevant mutations in several cancer-related genes, and the comparative mRNA expression analysis showed 36 differentially expressed genes associated with EGFR tyrosine kinase inhibitors resistance, RAS, MAPK, and mTOR signaling. Importantly, we observed that overexpression of KRAS, RhoA, and CD44 was associated with cetuximab resistance. Protein analysis revealed EGFR phosphorylation inhibition and mTOR increase in resistant cells. Moreover, the resistant cell line demonstrated an aggressive phenotype with a significant increase in adhesion, the number of colonies, and migration rates. Overall, we identified several molecular alterations in the cetuximab resistant cell line that may constitute novel biomarkers of cetuximab response such as mTOR and RhoA overexpression. These findings indicate new strategies to overcome anti-EGFR resistance in HNSCC.