Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm defined by the presence of t(9;22) translocation whose origin has been associated with the tridimensional genome organization. This rearrangement leads to the fusion of BCR and ABL1 genes giving rise to a chimeric protein with constitutive kinase activity. Imatinib, a tyrosine kinase inhibitor (TKI), is used as a first-line treatment for CML, though approximately 40% of CML patients do not respond. Here, using structured illumination microscopy (SIM) and 3D reconstruction, we studied the 3D organization patterns of the ABL1 and BCR genes, and their chromosome territories (CTs) CT9 and CT22, in CD34+ cells from CML patients that responded or not to TKI. We found that TKI resistance in CML is associated with high levels of structural disruption of CT9 and CT22 in CD34+ cells, increased CT volumes (especially for CT22), intermingling between CT9 and CT22, and open-chromatin epigenetic mark in CT22. Altogether our results suggest that large-scale disruption of CT9 and CT22 correlates with the clinical response of CML patients, which could be translated into a potential prognostic marker of response to treatment in this disease and provide novel insights into the mechanisms underlying resistance to TKI in CML.

Marijuana (Cannabissp.) is among the most recurred controlled substances in the world, and there is a growing tendency to legalize its possession and use; however, the genotoxic effects of marijuana remain under debate. A clear definition of marijuana's genotoxic effects remains obscure by the simultaneous consumption of tobacco and other recreational substances. In order to assess the genotoxic effects of marijuana and to prevent the bias caused by the use of substances other than cannabis, we recruited marijuana users that were sub-divided into three categories: (1) users of marijuana-only (M), (2) users of marijuana and tobacco (M+T), and (3) users of marijuana plus other recreative substances or illicit drugs (M+O), all the groups were compared against a non-user control group. We quantified DNA damage by detection of γH2AX levels and quantification of micronuclei (MN), one of the best-established methods for measuring chromosomal DNA damage. We found increased levels of γH2AX in peripheral blood lymphocytes from the M and M+T groups, and increased levels of MNs in cultures from M+T group. Our results suggest a DNA damage increment for M and M+T groups but the extent of chromosomal damage (revealed here by the presence of MNs and NBuds) might be related to the compounds found in tobacco. We also observed an elevated nuclear division index in all marijuana users in comparison to the control group suggesting a cytostatic dysregulation caused by cannabis use. Our study is the first in Mexico to assess the genotoxicity of marijuana in mono-users and in combination with other illicit drugs.

The long noncoding RNA (lncRNA) telomeric repeat-containing RNA (TERRA) has been associated with telomeric homeostasis, telomerase recruitment, and the process of chromosome healing; nevertheless, the impact of this association has not been investigated during the carcinogenic process. Determining whether changes in TERRA expression are a cause or a consequence of cell transformation is a complex task because studies are usually carried out using either cancerous cells or tumor samples. To determine the role of this lncRNA in cellular aging and chromosome healing, we evaluated telomeric integrity and TERRA expression during the establishment of a clone of untransformed myeloid cells. We found that reduced expression of TERRA disturbed the telomeric homeostasis of certain loci, but the expression of the lncRNA was affected only when the methylation of subtelomeric bivalent chromatin domains was compromised. We conclude that the disruption in TERRA homeostasis is a consequence of cellular transformation and that changes in its expression profile can lead to telomeric and genomic instability.

Electrospun membranes (EMs) have a wide range of applications, including use as local delivery systems. In this study, we manufactured a polyurethane Tecoflex™ EM loaded with bismuth-based lipophilic nanoparticles (Tecoflex™ EMs-BisBAL NPs). The physicochemical and mechanical characteristics, along with the antitumor and bactericidal effects, were evaluated using a breast cancer cell line and methicillin-susceptible and resistant Staphylococcus aureus (MRSA). Drug-free Tecoflex™ EMs and Tecoflex™ EMs-BisBAL NPs had similar fiber diameters of 4.65 ± 1.42 µm and 3.95 ± 1.32 µm, respectively. Drug-free Tecoflex™ EMs did not negatively impact a human fibroblast culture, indicating that the vehicle is biocompatible. Tecoflex™ EMs-BisBAL NPs increased 94% more in size than drug-free Tecoflex™ EMs, indicating that the BisBAL NPs enhanced hydration capacity. Tecoflex™ EMs-BisBAL NPs were highly bactericidal against both methicillin-susceptible S. aureus and MRSA clinical isolates, inhibiting their growth by 93.11% and 61.70%, respectively. Additionally, Tecoflex™ EMs-BisBAL NPs decreased the viability of MCF-7 tumor cells by 86% after 24 h exposure and 70.1% within 15 min. Regarding the mechanism of action of Tecoflex™ EMs-BisBAL NPs, it appears to disrupt the tumor cell membrane. In conclusion, Tecoflex™ EMs-BisBAL NPs constitute an innovative low-cost drug delivery system for human breast cancer and postoperative wound infections.