Differential Genetic and Functional Markers of Second Neoplasias in Hodgkin´s Disease Patients

The mechanisms involved in the appearance of a second neoplasia in patients with Hodgkin´s disease (HD) may be probably related with the genomic damage induced by the administrated treatments and its repair. Evaluate using the Comet Assay whether baseline, induced and unrepaired DNA damage differ in HD patients who did not develop a second neoplasia (HD-NST), HD patients who developed a second tumor (HD-ST) and healthy individuals, and to identify, through cDNA microarray hybridization, an expression signature of genes which could discriminate among the three groups. Baseline, induced and unrepaired DNA damage was higher in HD-ST than in HD-NST and in the latest group higher than in healthy donors. The genomic approach revealed two set of genes that discriminated between healthy subjects and patients and among the 3 sets of individuals. Hsp40, RAD50, TPMT, Rap2a, E2F2, EPHX2, TBX21 and BATF were validated by RT-PCR. Functional and genomics techniques revealed that alterations in cell cycle, repair, detoxifying and stress response pathways could be involved in the development of HD and in the occurrence of a primary second neoplasia in these patients. Both approaches may be useful as biological markers in the clinical setting. We have measured the relative abundance of RNA species in plasma through microarray hybridization, by comparing RNA isolated and amplified from 3 samples classes: - 9 patients with Hodgkin´s Disease who did not develop a second neoplasia (HD-NST) - 9 patients with Hodgkin´s disease who developed a second tumor against (HD-ST) - 9 healthy donors. For each population’s series (healthy individuals, HD-ST and HD-NST), 3 different pooled samples were obtained by mixing equal amounts of RNA from three individual samples of each series. Each pooled sample was competitively hybridized against a common reference formed by a pool of samples from the 9 healthy donors.