Frequent induction of chromosomal aberrations in in vivo skin fibroblasts after allogeneic stem cell transplantation: hints to chromosomal instability after irradiation

Spontaneous and Radiation-Induced Chromosome Aberrations in Primary Fibroblasts of Patients With Pediatric First and Second Neoplasms

The purpose of the present study was to investigate whether former childhood cancer patients who developed a subsequent secondary primary neoplasm (SPN) are characterized by elevated spontaneous chromosomal instability or cellular and chromosomal radiation sensitivity as surrogate markers of compromised DNA repair compared to childhood cancer patients with a first primary neoplasm (FPN) only or tumor-free controls. Primary skin fibroblasts were obtained in a nested case-control study including 23 patients with a pediatric FPN, 22 matched patients with a pediatric FPN and an SPN, and 22 matched tumor-free donors. Clonogenic cell survival and cytogenetic aberrations in Giemsa-stained first metaphases were assessed after X-irradiation in G1 or on prematurely condensed chromosomes of cells irradiated and analyzed in G2. Fluorescence in situ hybridization was applied to investigate spontaneous transmissible aberrations in selected donors. No significant difference in clonogenic survival or the average yield of spontaneous or radiation-induced aberrations was found between the study populations. However, two donors with an SPN showed striking spontaneous chromosomal instability occurring as high rates of numerical and structural aberrations or non-clonal and clonal translocations. No correlation was found between radiation sensitivity and a susceptibility to a pediatric FPN or a treatment-associated SPN. Together, the results of this unique case-control study show genomic stability and normal radiation sensitivity in normal somatic cells of donors with an early and high intrinsic or therapy-associated tumor risk. These findings provide valuable information for future studies on the etiology of sporadic childhood cancer and therapy-related SPN as well as for the establishment of predictive biomarkers based on altered DNA repair processes.

Molecular karyotyping and gene expression analysis in childhood cancer patients

Abstract

The genetic etiology of sporadic childhood cancer cases remains unclear. We recruited a cohort of 20 patients who survived a childhood malignancy and then developed a second primary cancer (2N), and 20 carefully matched patients who survived a childhood cancer without developing a second malignancy (1N). Twenty matched cancer-free (0N) and additional 1000 (0N) GHS participants served as controls. Aiming to identify new candidate loci for cancer predisposition, we compared the genome-wide DNA copy number variations (CNV) with the RNA-expression data obtained after in vitro irradiation of primary fibroblasts. In 2N patients, we detected a total of 142 genes affected by CNV. A total of 53 genes of these were not altered in controls. Six genes (POLR3F, SEC23B, ZNF133, C16orf45, RRN3, and NTAN1) that we found to be overexpressed after irradiation were also duplicated in the genome of the 2N patients. For the 1N collective, 185 genes were affected by CNV and 38 of these genes were not altered in controls. Five genes (ZCWPW2, SYNCRIP, DHX30, DHRS4L2, and THSD1) were located in duplicated genomic regions and exhibited altered RNA expression after irradiation. One gene (ABCC6) was partially duplicated in one 1N and one 2N patient. Analysis of methylation levels of THSD1 and GSTT2 genes which were detected in duplicated regions and are frequently aberrantly methylated in cancer showed no changes in patient’s fibroblasts. In summary, we describe rare and radiation-sensitive genes affected by CNV in childhood sporadic cancer cases, which may have an impact on cancer development.

Key messages

• Rare CNV’s may have an impact on cancer development in sporadic, non-familial, non-syndromic childhood cancer cases.

• In our cohort, each patient displayed a unique pattern of cancer-related gene CNVs, and only few cases shared similar CNV.

• Genes that are transcriptionally regulated after radiation can be located in CNVs in cancer patients and controls.

• THSD1 and GSTT2 methylation is not altered by CNV.

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01937-4) contains supplementary material, which is available to authorized users.

Clinical course of autologous recovery with chromosomal abnormalities after allogeneic hematopoietic stem cell transplantation

After primary graft failure following allogeneic hematopoietic stem cell transplantation, some patients experience autologous recovery of hematopoiesis without salvage transplantation. However, clinicians occasionally encounter unusual chromosomal abnormalities in recipient cells, not related to the original underlying diseases. In this study, through a survey based on data from the nationwide registry at the Japan Society for Hematopoietic Cell Transplantation, 42 patients were identified as having chromosomal abnormalities after autologous recovery. The complex chromosomal abnormalities were not consistent and randomly changed at each testing. Of the 42 patients, seven experienced disappearance of chromosome abnormalities without any treatment, and the probability was estimated as 17.4% (95% CI: 7.5-30.7%) at the 5-year observation. On the other hand, two patients developed hematologic malignancy at 1447 and 6202 days. Ten patients were alive without relapse or development of hematologic disorders, even though chromosomal abnormalities were continuously detected at a median of 3192 (103-4710) days. In conclusion, chromosomal abnormalities can persist for more than 10 years, and may eventually contribute to hematologic malignancy development in a small fraction of cases. Although oncogenic effects of the chromosomal abnormalities are still unclear, these findings may provide supporting evidence for late occurrence of secondary malignant neoplasms after cancer treatment.

Clinical and treatment-related features determining the risk of late relapse in patients with diffuse large B-cell lymphoma

It is still unclear whether there are clinically exploitable differences in the biology and behaviour of early versus late relapses in diffuse large B-cell lymphoma (DLBCL). The present study aimed to analyse a large population-based DLBCL cohort in order to identify (i) the frequency of late relapses (LR), (ii) parameters influencing the risk of LR, and (iii) the impact of introducing rituximab on the occurrence of LR. The data of 7247 DLBCL patients was obtained from the Danish Lymphoma Group Registry. Patients with LR had a lower International Prognostic Index and better performance score than early relapse (ER) patients. The use of radiotherapy lowered only the rate of ER while the use of rituximab yielded a lower occurrence of both ER and LR (P < 0·0001 and P < 0·0001, respectively), possibly suggesting a longer-lasting biological effect. Additionally, we found a female overrepresentation among LR patients that had received a rituximab-containing first line treatment. It was found that patients with LR had a significantly better 5-year overall survival compared to ER patients. In conclusion, LR was more frequently associated with low-risk features than ER. Furthermore, we found that the use of modern immunochemotherapy regimens in DLBCL lowers the risk of both ER and LR.

Biodosimetry of Persons Chronically Exposed to Low and Therapeutic Doses of Ionizing Radiation

Dynamic changes of the chromosomal aberrations and the DNA damage were analyzed in individuals exposed to low and therapeutic doses of radiation. The investigation included 37 persons living in areas where the radioactive sources were discovered 10–12 years ago. It was established by biodosimetry methods that the examined persons had absorbed dose of 0.2–0.7 Gy or had increased number of chromosomal aberrations, though insufficient to determine a dose. Clinical examination, chromosomal analysis, and assay of DNA damage by the comet (single-cell gel electrophoresis) assay were carried out. There was no correlation between the doses received 10 years ago and the cytogenetic changes with clinical outcome. The effect of the local fractionated gamma-irradiation with doses of 40–70 Gy was studied in cancer patients with localized head and neck tumors. The study of chromosomal abnormalities, the DNA damages by the comet assay, and the micronuclei detection of the buccal cells revealed a statistically significant correlation between the initial cytogenetic indices in cancer patients and their dynamic changes during and after the radiation exposure. In addition, the correlation was detected between the initial cytogenetic parameters and the functional stage of red blood system. Our results allow us to conclude that there is a need for further research to estimate the individual radiation risk to optimize and individualize the subsequent medical management of radiotherapy.