Sister chromatid cohesion defects are associated with chromosomal copy number heterogeneity in high hyperdiploid childhood acute lymphoblastic leukemia

High hyperdiploid acute lymphoblastic leukemia (ALL) is one of the most common malignancies in children. The main driver event of this disease is a nonrandom aneuploidy consisting of gains of whole chromosomes but without overt evidence of chromosomal instability (CIN). Here, we investigated the frequency and severity of defective sister chromatid cohesion-a phenomenon related to CIN-in primary pediatric ALL. We found that a large proportion (86%) of hyperdiploid cases displayed aberrant cohesion, frequently severe, to compare with 49% of ETV6/RUNX1-positive ALL, which mostly displayed mild defects. In hyperdiploid ALL, cohesion defects were associated with increased chromosomal copy number heterogeneity, which could indicate increased CIN. Furthermore, cohesion defects correlated with RAD21 and NCAPG mRNA expression, suggesting a link to reduced cohesin and condensin levels in hyperdiploid ALL. Knockdown of RAD21 in an ALL cell line led to sister chromatid cohesion defects, aberrant mitoses, and increased heterogeneity in chromosomal copy numbers, similar to what was seen in primary hyperdiploid ALL. In summary, our study shows that aberrant sister chromatid cohesion is frequent but heterogeneous in pediatric high hyperdiploid ALL, ranging from mild to very severe defects, and possibly due to low cohesin or condensin levels. Cases with high levels of aberrant chromosome cohesion displayed increased chromosomal copy number heterogeneity, possibly indicative of increased CIN. These abnormalities may play a role in the clonal evolution of hyperdiploid pediatric ALL.

Psychiatric disorders in offspring of childhood or adolescent central nervous system tumor survivors: a national cohort study

BACKGROUND

Children experience a higher risk of psychiatric problems when their parents are diagnosed with cancer. However, the psychological effect among offspring who are born after parental cancer diagnosed in childhood or adolescence is unknown. We aimed to investigate the risk of psychiatric disorders in children of survivors with childhood or adolescent central nervous system (CNS) tumors.

METHODS

By combining several nationwide Swedish registers, we identified all children who had at least one parent previously diagnosed with CNS tumor below the age of 20. Five children without parental CNS tumor were randomly selected for the matching. Cox proportional hazards model was used to calculate hazard ratios (HRs) with 95% confidence interval (CI).

RESULTS

The incidence rate of psychiatric disorders was 8.46 per 1000 person-years in children of CNS tumor survivors, whereas the rate was 7.47 in the matched comparisons, yielding an adjusted HR of 1.10 (95% CI = 0.94, 1.28). Boys of survivors had a higher risk of psychiatric disorders (adjusted HR = 1.29, 95% CI = 1.04, 1.59). The risk of the specific types of psychiatric disorders in children of tumor survivors was comparable with that in the matched comparisons, except for mental retardation. Children of survivors experienced 2.36 times higher risk of mental retardation (95% CI = 1.21, 4.58), mainly of mild mental retardation (adjusted HR = 2.99, 95% CI = 1.40, 6.38).

CONCLUSION

Children of survivors with CNS tumor in early life did not experience a significantly increased risk of overall psychiatric disorders, with the exception of an elevated risk of mental retardation that was mainly mild.

Poly-aneuploid cancer cells promote evolvability, generating lethal cancer

Cancer cells utilize the forces of natural selection to evolve evolvability allowing a constant supply of heritable variation that permits a cancer species to evolutionary track changing hazards and opportunities. Over time, the dynamic tumor ecosystem is exposed to extreme, catastrophic changes in the conditions of the tumor-natural (e.g., loss of blood supply) or imposed (therapeutic). While the nature of these catastrophes may be varied or unique, their common property may be to doom the current cancer phenotype unless it evolves rapidly. Poly-aneuploid cancer cells (PACCs) may serve as efficient sources of heritable variation that allows cancer cells to evolve rapidly, speciate, evolutionarily track their environment, and most critically for patient outcome and survival, permit evolutionary rescue, therapy resistance, and metastasis. As a conditional evolutionary strategy, they permit the cancer cells to accelerate evolution under stress and slow down the generation of heritable variation when conditions are more favorable or when the cancer cells are closer to an evolutionary optimum. We hypothesize that they play a critical and outsized role in lethality by their increased capacity for invasion and motility, for enduring novel and stressful environments, and for generating heritable variation that can be dispensed to their 2N+ aneuploid progeny that make up the bulk of cancer cells within a tumor, providing population rescue in response to therapeutic stress. Targeting PACCs is essential to cancer therapy and patient cure-without the eradication of the resilient PACCs, cancer will recur in treated patients.