Claudia M. García-Cuellar

Colorectal cancer (CRC) is one of the leading causes of mortality worldwide, with rising cases in individuals under 50 years old, classified as early-onset CRC (EO-CRC). EO-CRC is characterized by having clinical features related to a worse prognosis and outcome. This underscores the critical need for early detection biomarkers. ncRNAs emerge as potential biomarkers for diagnosis, prognosis, and treatment response in other types of cancers. Sequencing data from the NCBI Bioproject PRJNA787417 were analyzed to identify differentially expressed miRNAs in early- and late-onset colorectal cancer (EO-CRC and LO-CRC). Differential expressions were assessed with a log fold change threshold of 1 and an adjusted p-value of 0.05. Predicted mRNA targets were identified via ENCORI and analyzed for pathway enrichment using the SHINYGO algorithm. RNA-seq analysis identified a 25-ncRNA EO-CRC signature, including hsa-miR-195 (downregulated) and hsa-miR-549a (upregulated), with enrichment analyses suggesting associations with MAPK, PI3K, VEGF, and KRAS pathways commonly linked to angiogenesis, migration, and invasion. This preliminary report highlights a 25-gene deregulated signature in EO-CRC, in which hsa-miR-195 and hsa-miR-549a emerge as biomarkers of clinical relevance, regulating key genes involved in angiogenesis, migration, and invasion. Their dysregulation could contribute to the aggressive clinical features and poor outcomes observed in EO-CRC.

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies affecting the head and neck and account for over 90% of all oral cancers (1)

The global population constantly breathes particulate matter with an aerodynamic diameter of ≤10 µm (PM₁₀)—a human carcinogen linked to lung cancer. Previous studies have indicated that PM₁₀ causes DNA damage, including double-strand breaks (DSBs). In particular, DSBs are primarily repaired by the non-homologous end joining (NHEJ) pathway, which is essential for maintaining genomic stability; however, the effects of PM₁₀ exposure on this pathway are unknown. To address this, A549 lung epithelial cells were exposed to 10 µg/cm² of PM₁₀ for 6, 12, and 24 h. We determined that DSBs increased with prolonged exposure, and an increase in the frequency of micronuclei was found. Despite the accumulated DNA damage, no changes in the cell cycle were observed. Reductions in the levels of the Ku80 gene and protein, as well as the Ku70–Ku80 heterodimer—which is essential for initiating NHEJ-mediated repair—were observed. Levels of Artemis (which is responsible for processing DNA damage) remained stable, while levels of the XRCC4 gene and protein (responsible for completing repair) decreased. We conclude that PM₁₀ disrupts two key proteins in the NHEJ pathway, impairing the capacity for DSB repair. This could promote the accumulation of DNA damage and induce genomic instability, contributing to the development of cancer.

In cells, oxidative stress is an imbalance between the production/accumulation of oxidants and the ability of the antioxidant system to detoxify these reactive products. Reactive oxygen species (ROS), cause multiple cellular damages through their interaction with biomolecules such as lipids, proteins, and DNA. Genotoxic damage caused by oxidative stress has become relevant since it can lead to mutation and play a central role in malignant transformation. The evidence describes chronic oxidative stress as an important factor implicated in all stages of the multistep carcinogenic process: initiation, promotion, and progression. In recent years, ambient air pollution by particulate matter (PM) has been cataloged as a cancer risk factor, increasing the incidence of different types of tumors. Epidemiological and toxicological evidence shows how PM-induced oxidative stress could mediate multiple events oriented to carcinogenesis, such as proliferative signaling, evasion of growth suppressors, resistance to cell death, induction of angiogenesis, and activation of invasion/metastasis pathways. In this review, we summarize the findings regarding the involvement of oxidative and genotoxic mechanisms generated by PM in malignant cell transformation. We also discuss the importance of new approaches oriented to studying the development of tumors associated with PM with more accuracy, pursuing the goal of weighing the impact of oxidative stress and genotoxicity as one of the main mechanisms associated with its carcinogenic potential.