Human de novo papillary renal-cell carcinomas in a kidney graft: evidence of recipient origin with adenoma-carcinoma sequence

Papillary renal-cell carcinoma (pRCC) is unusual for its occurrence in kidneys with chronic dysfunction, for its frequent multifocality and for its common association with papillary adenoma, a benign renal lesion morphologically indistinguishable from pRCC. Concomitant development of papillary adenoma and pRCC in five transplanted kidneys, where donor and recipient characteristics are well established, provided a unique opportunity for molecular studies of de novo pRCC carcinogenesis. We aimed to study this tumor type to determine whether or not the different papillary tumors have the same origin, and whether or not papillary adenomas are precursor lesions of pRCC. We performed XY-FISH in sex-mismatched kidney transplants, and polymorphic microsatellite DNA and high-resolution melting of mitochondrial DNA analyzes in all five patients on laser-microdissected tumor cells, then compared these molecular profiles to donor and recipient profiles. This study (i) identified the recipient origin of de novo papillary adenomas and pRCCs in a kidney transplant, (ii) demonstrated an identical origin for precursor cells of papillary adenomas and pRCCs and (iii) showed additional genetic alterations in pRCCs compared to papillary adenomas. This molecular approach of papillary tumors developed in transplanted kidney identified successive steps in carcinogenesis of human de novo papillary renal-cell carcinoma.

Changes in allelic imbalances in locally advanced breast cancers after chemotherapy

In advanced breast cancers, TP53 mutation is highly predictive of complete response to high-dose epirubicin/cyclophosphamide chemotherapy. In these tumours with an altered control of genomic stability, accumulation of chemotherapy-induced genetic alterations may contribute to cell death and account for complete response. To explore the effects of chemotherapy on stability of the tumour genome, allelic profiles were obtained from microdissected tumour samples before and after chemotherapy in 29 unresponsive breast cancers (9 with TP53 mutation). Ninety-four per cent allelic profiles remained unchanged after treatment. Interestingly, 11 profiles (6%) showed important changes after treatment; allelic imbalances significantly increased (four cases) or decreased (seven cases) after chemotherapy in three distinct experiments, two of which using laser microdissected tumour cells. These genetic changes were not linked to the TP53 status, but one tumour showed complete disappearance of TP53-mutated cells in the residual tumour after treatment. Altogether, these observations carry important implications for the clonal evolution of breast cancers treated with DNA-damaging agents, as they point both to the importance of tumour heterogeneity and chemotherapy-driven selection of subclones.