Colorectal cancer is a heterogeneous disease caused by both genetic and epigenetics factors. Analysing DNA methylation changes occurring during colorectal cancer progression and metastasis formation is crucial for the identification of novel epigenetic markers of patient prognosis. Genome-wide methylation sequencing of paired samples of colon (normal adjacent, primary tumour and lymph node metastasis) showed global hypomethylation and CpG island (CGI) hypermethylation of primary tumours compared to normal. In metastasis we observed high global and non-CGI regions methylation, but lower CGI methylation, compared to primary tumours. Gene ontology analysis showed shared biological processes between hypermethylated CGIs in metastasis and primary tumours. After complementary analysis with The Cancer Genome Atlas (TCGA) cohort, FIGN, HTRA3, BDNF, HCN4 and STAC2 genes were found associated with poor survival. We mapped the methylation landscape of colon normal tissues, primary tumours and lymph node metastasis, being capable of identified methylation changes throughout the genome. Furthermore, we found five genes with potential for methylation biomarkers of poor prognosis in colorectal cancer patients.

The Epstein–Barr virus (EBV) is a globally dispersed pathogen involved in several human cancers of B-cell and non-B-cell origin. EBV has been classified into EBV-1 and EBV-2, which have differences in their transformative ability. EBV-1 can transform B-cells into LCL more efficiently than EBV-2, and EBV-2 preferentially infects T-cell lymphocytes. The EBNA3A oncoprotein is a transcriptional regulator of virus and host cell genes, and is required in order to transform B-cells. EBNA3A has six peptide motifs called nuclear localization signals (NLSs) that ensure nucleocytoplasmic protein trafficking. The presence of multiple NLSs has been suggested to enhance EBNA3 function or different specificities in different cell types. However, studies about the NLS variability associated with EBV types are scarce. Based on a systematic sequence analysis considering more than a thousand EBNA3A sequences of EBV from different human clinical manifestations and geographic locations, we found differences in NLSs’ nucleotide structures among EBV types. Compared with the EBNA3A EBV-1, EBNA3A EBV-2 has two of the six NLSs altered, and these mutations were possibly acquired by recombination. These genetic patterns in the NLSs associated with EBV-1 and EBV-2 provide new information about the traits of EBNA3A in EBV biology.

Human T-cell lymphotropic virus type 1 (HTLV-1) is a virus spread worldwide. It is estimated that there are about 5 - 10 million infected people in the world. In Chile, HTLV is endemic with higher seroprevalence among indigenous people, nonetheless little is known about the HTLV-1 genetic diversity, its introduction, and dispersion in this country. To gain insights into these issues, we conducted a phylogenetic dating analysis based on Chilean and closed related long terminal sequences (LTR) sequences. The time tree reconstruction showed that the introduction of HTLV-1aA occurred several times in Chile. We hypothesize that these introductions take place at least into different historical moments: (i) during the ancient human migrations and (ii) during/posterior the European colonization of South America. The present study contributes toward understanding the evolutionary history of HTLV-1 in Chile and South America.

Photodynamic therapy (PDT) treats nonmelanoma skin cancer. PDT kills cells through reactive oxygen species (ROS), generated by interaction among cellular O_2, photosensitizer and specific light. Protoporphyrin IX (PpIX) is a photosensitizer produced from methyl aminolevulinate (MAL) by heme group synthesis (HGS) pathway. In PDT-resistant cells, PDT efficacy has been improved by addition of epigallocatechin gallate (EGCG). Therefore, the aim of this work is to evaluate the effect of EGCG properties over MAL-TFD and PpIX production on A-431 cell line. EGCG’s role over cell proliferation (flow cytometry and wound healing assay) and clonogenic capability (clonogenic assay) was evaluated in A-431 cell line, while the effect of EGCG over MAL-PDT was determined by cell viability assay (MTT), PpIX and ROS detection (flow cytometry), intracellular iron quantification and gene expression of HGS enzymes (RT-qPCR). Low concentrations of EGCG (<50 µM) did not have an antiproliferative effect over A-431 cells; however, EGCG inhibited clonogenic cell capability. Furthermore, EGCG (<50 µM) improved MAL-PDT cytotoxicity, increasing PpIX and ROS levels, exerting a positive influence on PpIX synthesis, decreasing intracellular iron concentration and modifying HGS enzyme gene expression such as PGB (upregulated) and FECH (downregulated). EGCG inhibits clonogenic capability and modulates PpIX synthesis, enhancing PDT efficacy in resistant cells.

Ovarian cancer (OC) remains one of the deadliest gynecological malignancies, largely due to late diagnosis and the emergence of resistance to platinum–based chemotherapy. Long non–coding RNAs (lncRNAs) have recently emerged as key regulators of tumor progression and therapeutic adaptation. In this study, we performed integrative transcriptomic profiling of patient–derived TCGA ovarian tumor samples and carboplatin–resistant A2780 (CBDCA–R–A2780) cells to identify lncRNAs whose dysregulation overlaps between a cell–line resistance model and patient tumors. Our analyses revealed extensive transcriptional remodeling across both datasets, with MNX1–AS1 consistently emerging as a strongly deregulated transcript. Differential expression analysis showed robust upregulation of MNX1–AS1 in resistant cells and tumor tissues, accompanied by correlations with epithelial–mesenchymal transition (EMT)–related transcription factors such as FOXA1 and SNAI2 and inverse associations with epithelial markers including CDH1. Computational predictions using RIblast identified specific MNX1–AS1 binding regions with candidate miRNAs and mRNAs, prioritizing EMT–related transcripts (e.g., SNAI2, FOXA1, ZEB1) with favorable hybridization energies for future validation. Additional prioritized interactors included genes linked to stress response (IER2, FOSB) and invasion (MMP11, MMP1). Because A2780 has been discussed as an endometrioid–like/non–serous ovarian cancer model, mechanistic inferences primarily apply to this in vitro context, while TCGA analyses provide associative support rather than mechanistic validation. Collectively, these findings highlight MNX1–AS1 as a candidate regulator associated with transcriptional reprogramming in OC and a promising prognostic biomarker warranting further functional testing.