Ongoing chromosomal instability in neoplasia (CIN) generates intratumor genomic heterogeneity and limits the efficiency of oncotherapeutics. Neoplastic human cells utilizing the alternative lengthening of telomeres (ALT)-pathway, display extensive structural and numerical CIN. To unravel patterns of genome evolution driven by oncogene-replication stress, telomere dysfunction, or genotoxic therapeutic interventions, we examined by comparative genomic hybridization five karyotypically-diverse outcomes of the ALT osteosarcoma cell line U2-OS. These results demonstrate a high tendency of the complex cancer genome to perpetuate specific genomic imbalances despite the karyotypic evolution, indicating an ongoing process of genome dosage maintenance. Molecular karyotyping in four ALT human cell lines showed that mitotic cells with low levels of random structural CIN display frequent evidence of whole genome doubling (WGD), suggesting that WGD may protect clonal chromosome aberrations from hypermutation. We tested this longstanding hypothesis in ALT cells exposed to gamma irradiation or to inducible DNA replication stress under overexpression of p21. Single-cell cytogenomic analyses revealed that although polyploidization promotes genomic heterogeneity, it also protects the complex cancer genome and hence confers genotoxic therapy resistance by generating identical extra copies of driver chromosomal aberrations, which can be spared in the process of tumor evolution if they undergo unstable or unfit rearrangements.

Leukocyte telomere length (LTL) is shortened in adults with type 1 diabetes (T1D), but less data is available concerning pediatric cases. Multiple factors affect LTL, namely genes, epigenetics, environmental factors, oxidation, and psychological stress. Children with T1D and their families experience chronic stress. This study aimed to investigate LTL in children with T1D (n = 35) aged 6–13 years old, in comparison to age-matched healthy counterparts (n = 35), and assess any correlation of LTL with perceived stress. Relative LTL (rLTL) was assessed through real-time qPCR. Morning serum cortisol, high-sensitivity C-Reactive Protein (hsCRP), and glycated hemoglobin (HbA1c) were measured. Children completed the validated questionnaires “Stress in Children” and “Pediatric Quality of Life”. Parents answered the “Perceived Stress Scale”. Children with T1D had a lower rLTL (p = 0.02) compared to age-matched healthy controls, higher hsCRP (p = 0.031), and a lower estimated quality of life (p = 0.01). RLTL was found to be lower in females with T1D (p < 0.001) and was positively related to the ‘gender–social support’ factor (p = 0.002) and diabetes duration (p = 0.045), adjusted for children’s age, parental age, and sociodemographic characteristics. These pilot findings indicate early emergence of shorter rLTL in T1D, pointing to a sexual dimorphism pattern. Insights into preventing LTL shortening in pediatric T1D can be gained from large-scale studies examining the impact of gender and social support.