5-aza-2'-deoxycytidine induces telomere dysfunction in breast cancer cells.

AIMS: Azacitidine, a drug that epigenetically modifies DNA, is widely used to treat haematological malignancies. However, at low doses, it demethylates DNA, and as a result, can alter gene expression. In our previous publication, we showed that low doses of azacitidine induce telomere length elongation in breast cancer cells. In this study, we aim to identify the mechanisms which lead to telomere length increases. METHODS: Breast cancer cell lines representing different molecular sub-types were exposed to 5-aza-2'-deoxycytidine (5-aza) in 2 and 3D cultures, followed by DNA, RNA, and protein extractions. Samples were then analysed for telomere length, DNA damage, telomerase, and ALT activity. RESULTS: We show that treatment of the cell lines with 5-aza for 72 h induced DNA damage at the telomeres and increased ALT activity 3-fold. We also identified a gene, POLD3, which may be involved in the ALT activity seen after treatment. CONCLUSION: Our results indicate that while 5-aza is a useful drug for treating haematological cancers, surviving cancer cells that have been exposed to lower doses of the drug may activate mechanisms such as ALT. This could lead to cancer cell survival and possible resistance to 5-aza clinically.

Burden of cardiovascular disease attributable to particulate matter pollution in the eastern Mediterranean region: analysis of the 1990-2019 global burden of disease.

AIMS: Particulate matter pollution is the most important environmental mediator of global cardiovascular morbidity and mortality. Air pollution evidence from the Eastern Mediterranean Region (EMR) is limited, owing to scarce local studies, and the omission from multinational studies. We sought to investigate trends of particulate matter (PM2.5)-related cardiovascular disease (CVD) burden in the EMR from 1990 to 2019. METHODS AND RESULTS: We used the 1990-2019 global burden of disease methodology to investigate total PM2.5, ambient PM2.5, and household PM2.5-related CVD deaths and disability-adjusted life years (DALYs) and cause-specific CVD mortality in the EMR. The average annual population-weighted PM2.5 exposure in EMR region was 50.3 µg/m3 [95% confidence interval (CI):42.7-59.0] in 2019, which was comparable with 199 048.1 µg/m3 (95% CI: 36.5-65.3). This was despite an 80% reduction in household air pollution (HAP) sources since 1990. In 2019, particulate matter pollution contributed to 25.67% (95% CI: 23.55-27.90%) of total CVD deaths and 28.10% (95% CI: 25.75-30.37%) of DALYs in the region, most of which were due to ischaemic heart disease and stroke. We estimated that 353 071 (95% CI: 304 299-404 591) CVD deaths in EMR were attributable to particulate matter in 2019, including 264 877 (95% CI: 218 472-314 057) and 88 194.07 (95% CI: 60 149-119 949) CVD deaths from ambient PM2.5 pollution and HAP from solid fuels, respectively. DALY's in 2019 from CVD attributable to particulate matter was 28.1% when compared with 26.69% in 1990. The age-standardized death and DALY rates attributable to air pollution was 2122 per 100 000 in EMR in 2019 and was higher in males (2340 per 100 000) than in females (1882 per 100 000). CONCLUSION: The EMR region experiences high PM2.5 levels with high regional heterogeneity and attributable burden of CVD due to air pollution. Despite significant reductions of overall HAP in the past 3 decades, there is continued HAP exposure in this region with rising trend in CVD mortality and DALYs attributable to ambient sources. Given the substantial contrast in disease burden, exposures, socio-economic and geo-political constraints in the EMR region, our analysis suggests substantial opportunities for PM2.5 attributable CVD burden mitigation.