Assessment of chimerism in epithelial cancers in transplanted patients.

Cancer is now the most severe complication in the long term in transplant recipients. As most solid-organ or hematopoietic stem-cell transplantations are allogeneic, chimerism studies can be performed on cancers occurring in recipients. We summarize here the different methods used to study chimerism in cancers developing in allogeneic-transplant recipients, analyze their respective advantages and report the main results obtained from these studies. Chimerism analyses of cancers in transplant recipients require methods suited to tissue samples. In the case of gender-mismatched transplantation, the XY chromosomes can be explored using fluorescent in situ hybridization on whole-tissue sections or Y-sequence-specific PCR after the laser microdissection of tumor cells. For cancers occurring after gender-matched transplantation, laser microdissection of tumor cells enables studies of microsatellite markers and high-resolution melting analysis of mitochondrial DNA on genes with marked polymorphism, provided these are different in the donor and the recipient. The results of different studies address the cancers that develop in both recipients and in transplants. The presence of chimeric cells in these two types of cancer implies an exchange of progenitor/stem-cells between transplant and recipient, and the plasticity of these progenitor/stem-cells contributes to epithelial cancers. The presence of chimeric cells in concomitant cancers and preneoplastic lesions implies that the oncogenesis of these cancers progresses through a multistep process.

Micromolecular methods for diagnosis and therapeutic strategy: a case study.

An intraductal carcinoma, 55 mm across, was diagnosed on a total mastectomy in a 45-year-old woman. The 2 micro-invasive areas found were too small for reliable immunostainings for estrogen, progesterone, and HER2 receptors. In the sentinel lymph-node, a subcapsular tumor embole of about 50 cancer cells was identified on the extemporaneous cryo-cut section, but not on further sections after paraffin-embedding of the sample. Considering this tumor metastatic potential, we decided to assess HER2 status on the metastatic embole using pathological and molecular micro-methods. We laser-microdissected the tumor cells, extracted their DNA, and performed droplet-digital-PCR (ddPCR) for HER2 gene copy number variation. The HER2/RNaseP allele ratio was 5.2 in the laser-microdissected tumor cells, similar to the 5.3 ratio in the HER2-overexpressing breast cancer cell line BT-474. We thus optimized the adjuvant treatment of our patient and she received a trastuzumab-based adjuvant chemotherapy.

Donor-derived stem-cells and epithelial mesenchymal transition in squamous cell carcinoma in transplant recipients.

BACKGROUND: Skin squamous-cell-carcinoma (SCC), is the main complication in long-term kidney-transplant recipients, and it can include donor-derived cells. Preclinical models demonstrated the involvement of epithelial mesenchymal transition (EMT) in the progression of skin SCC, and the role of Snail, an EMT transcription factor, in cancer stem-cell survival and expansion.Here, we studied stem-cells and EMT expression in SCCs and concomitant actinic keratoses (AK) in kidney-transplant recipients. METHODS: In SCC and AK in 3 female recipients of male kidney-transplants, donor-derived Y chromosome in epidermal stem cells was assessed using combined XY-FISH/CD133 immunostaining, and digital-droplet-PCR on laser-microdissected CD133 expressing epidermal cells.For EMT study, double immunostainings of CD133 with vimentin or snail and slug, electron microscopy and immunostainings of keratinocytes junctions were performed. Digital droplet PCR was used to check CDH1 (E-cadherin) expression level in laser-microdissected cells co-expressing CD133 and vimentin or snail and slug.The numbers of Y-chromosome were assessed using digital droplet PCR in laser-microdissected cells co-expressing CD133 and vimentin, or snail and slug, and in CD133 positive cells not expressing any EMT maker. RESULTS: We identified donor-derived stem-cells in basal layers and invasive areas in all skin SCCs and in concomitant AKs, but not in surrounding normal skin.The donor-derived stem-cells expressed the EMT markers, vimentin, snail and slug in SCCs but not in AKs. The expression of the EMT transcription factor, SNAI1, was higher in stem-cells when they expressed vimentin. They were located in invasive areas of SCCs. In these areas, the expressions of claudin-1 and desmoglein 1 were reduced or absent, and within the basal layer there were features of basal membrane disappearance.Donor-derived stem cells were in larger numbers in stem cells co-expressing vimentin or snail and slug than in stem cells not expressing any EMT marker. CONCLUSIONS: We identified here donor-derived stem cells within skin SCC in kidney-transplant recipients. They were located in invasive areas of SCC and had EMT characteristics.

Human skin carcinoma arising from kidney transplant-derived tumor cells.

Tumor cells with donor genotype have been identified in human skin cancer after allogeneic transplantation; however, the donor contribution to the malignant epithelium has not been established. Kidney transplant recipients have an increased risk of invasive skin squamous cell carcinoma (SCC), which is associated with accumulation of the tumor suppressor p53 and TP53 mutations. In 21 skin SCCs from kidney transplant recipients, we systematically assessed p53 expression and donor/recipient origin in laser-microdissected p53+ tumor cells. In one patient, molecular analyses demonstrated that skin tumor cells had the donor genotype and harbored a TP53 mutation in codon 175. In a kidney graft biopsy performed 7 years before the skin SCC diagnosis, we found p53+ cells in the renal tubules. We identified the same TP53 mutation in these p53+ epithelial cells from the kidney transplant. These findings provide evidence for a donor epithelial cell contribution to the malignant skin epithelium in the recipient in the setting of allogeneic kidney transplantation. This finding has theoretical implications for cancer initiation and progression and clinical implications in the context of prolonged immunosuppression and longer survival of kidney transplant patients.