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It has recently been shown that epithelial cells derived from stem cells originating outside the liver are integrated into liver allografts. Whether epithelial intragraft chimerism protects transplants from rejection or chronic transplant dysfunction, and whether it interferes with recurrence of primary liver disease, is not known. Twenty-seven sequential biopsies derived from 9 liver-transplant recipients were studied for chimerism of hepatocytes and cholangiocytes. The target cells were isolated by laser microdissection after cytokeratin immunolabeling and genotyped using DNA analysis of a highly polymorphic short tandem repeat. Irrespective of whether early (up to 4 weeks) or late (more than 12 months) posttransplantation biopsies were studied, cholangiocyte chimerism was almost constantly found in 91% of the samples. No significant differences occurred between samples derived from patients with chronic organ dysfunction (n = 3), recurrent hepatitis (n = 3), or mild, unspecific changes (n = 3). By contrast, hepatocyte chimerism tended to occur later (55% vs. 22%) and appeared to be associated with recurrent hepatitis (67% vs. 27%). In this respect, chronic organ dysfunction did not differ from mild, unspecific changes. While cholangiocyte chimerism represents a constant and early phenomenon in liver transplantations, an enhanced chimeric integration of recipient-derived hepatocytes can be observed in recurrent hepatitis, supporting the concept of an increased recruitment of extrahepatic progenitor cells to the liver in chronic hepatitis.

Ductal carcinoma in situ (DCIS), as an identifiable progenitor lesion of invasive breast cancer, represents a morphologically, biologically, and prognostically heterogeneous disease. It is not clear which molecular mechanisms are involved in progression to infiltrative growth. In this study, 83 DCIS classified according to the Van Nuys grading scheme were examined for amplification of growth regulatory genes that have been found to be amplified in invasive breast cancer (c-erbB2, topoisomerase IIalpha, c-myc, and cyclinD1 genes). Exact quantification of gene amplification was enabled by a combination of laser microdissection of paraffin-embedded tissue with real-time PCR. In DCIS, gene amplifications of all tested genes were found. The most frequently amplified gene was c-erbB2 found in 21 of 83 (25%) cases. Amplification of the other genes under investigation was observed in 4% to 6% of cases, high-grade DCIS being predominantly affected. High-grade DCIS differed significantly from low- and intermediate-grade DCIS in frequency and level of c-erbB2 amplification. In addition, high-grade DCIS revealed an accumulation of genetic aberrations. Amplification status in pure in situ lesions did not differ from intraductal carcinoma with an infiltrative component, indicating that although associated with a higher nuclear grade gene amplification might not represent an independent prognostic marker of disease progression.

The detection of donor-derived cells in the blood and tissues of graft recipients after solid organ transplantation is a readily observed phenomenon called microchimerism. Yet very little is known about the persistence and integration of recipient-derived cells in the transplanted organ, indicating a form of intragraft chimerism. To further study this phenomenon and its possible influence on graft acceptance or rejection, we developed the following novel approach. Immunohistochemically labeled cells were isolated by means of laser-based microdissection and subsequent laser pressure catapulting from paraffine-embedded posttransplantation biopsies. The following use of a highly sensitive PCR assay analyzing one polymorphic short tandem repeat (STR) marker enabled us to clearly identify the genotypes in samples containing as little as 10 isolated cells. The combination of laser-based microdissection and STR-PCR thus provides a powerful tool for the genotyping of even very few cells isolated from routinely processed biopsies after solid organ transplantation.

Gene amplification is one essential mechanism leading to oncogene activation which is supposed to play a major role in the pathogenesis of invasive breast cancer. However, using standard methodologies the detection of gene amplifications has been limited especially in small-sized lesions, like pre-invasive precursor lesions. The combination of two novel technologies, laser-based microdissection and quantitative real-time PCR, facilitates the detection of low-level amplifications in morphologically defined lesions. As a model system we investigated in situ breast cancer (ductal carcinoma in situ, DCIS) classified according to the morphology-based Van Nuys grading system for amplification of growth-regulatory genes. In this study 83 formalin-fixed, paraffin-embedded archival DCIS specimens were examined after laser-based microdissection by quantitative real-time PCR using the TaqMan® detection system for amplification of the c-erbB2, topoisomerase IIα, c-myc and cyclinD1 gene. In a subset of 17 DCIS with adjacent infiltrating tumour components we compared intraductal and invasive tumour components in parallel for differences in amplification status. The combination of these new techniques represents an excellent tool to gain new insights into carcinogenesis by analyzing genetic alterations in morphologically identified heterogeneous lesions in breast cancer progression within the very same specimen or even tissue slide.

BACKGROUND Hepatocellular carcinomas (HCC) that originate de novo in liver transplants without preceding HCC in the explanted organ have only rarely been reported. Because recent data demonstrated a mixed hepatocellular chimerism caused by the integration of host-derived stem cells, a study was conducted on the origin of tumor cells in de novo HCC. METHODS From two cases of de novo HCC arising in liver transplants after hepatitis B reinfection, tumor cells and non-neoplastic liver cells from the patient's own liver and donor liver were isolated by laser microdissection, and highly polymorphic short tandem DNA repeats (STR) were investigated. RESULTS Isolated tumor cells revealed donor-specific STR genotypes that could clearly be discriminated from the genotype of the host. CONCLUSIONS Hepatitis B virus-associated de novo HCC in liver transplants is of donor but not of host origin. The new technique described here can also discriminate between true recurrence of the original tumor and new recipient tumors.

The intermediate filament protein Nestin identifies stem/progenitor cells in adult tissues, but the function of Nestin is poorly understood. We investigated Nestin expression and function in common lethal cancers. Nestin mRNA was detected in cell lines from small cell lung, and breast cancers, and particularly elevated in cell lines derived from prostate cancer metastases. Whereas the androgen-independent lines PC3, 22RV1, and DU145 all expressed Nestin transcripts under standard culture conditions, the androgen-dependent line LnCaP expressed Nestin only on androgen withdrawal. We confirmed associations of Nestin expression, androgen withdrawal, and metastatic potential by immunohistochemical analysis of samples from 254 prostate cancer patients. Cytoplasmic Nestin protein was readily identifiable in prostate cancer cells from 75% of patients with lethal androgen-independent disease, even in cancer sampled from the prostate itself. However, Nestin expression was undetectable in localized androgen-deprived tumors and in metastases without prior androgen deprivation. To address its function, we reduced Nestin levels with short hairpin RNAs, markedly inhibiting in vitro migration and invasion in prostate cancer cells but leaving cell growth intact. Nestin knockdown also diminished metastases 5-fold compared with controls despite uncompromised tumorigenicity at the site of inoculation. These results specify a function for Nestin in cell motility and identify a novel pathway for prostate cancer metastasis. Activity of this pathway may be selected by the extraprostatic environment or, as supported by our data, may originate within the prostate after androgen deprivation. Further dissection of this novel Nestin migration pathway may lead to strategies to prevent and neutralize metastatic spread. [Cancer Res 2007;67(19):9199–206]

Although data regarding the role of the Notch pathway in human lung cancer are still limited, fetal lung developmental studies suggest that Notch signaling plays a critical role in regulating airway epithelial development. The moderate hypotrophic phenotype of lungs from animals bearing a Hes1 mutation, and the expression of Notch components in the distal lung bud during branching morphogenesis, together suggest that Notch may play a role in normal lung growth, especially in Clara cell precursors. Non-small cell lung cancers, including adenocarcinoma, appear to actively utilize this conserved developmental pathway. Pharmacologic inhibition of the Notch pathway is a potential experimental approach to lung cancer treatment.

Recent studies have demonstrated an integration of recipient-derived progenitor cells into solid allografts with differentiation into parenchymal cells. Whether or to what extent this phenomenon influences allograft outcome has still to be elucidated. To detect epithelial chimerism tubular cells were harvested from sequential renal allograft biopsy samples by laser microdissection in 36 patients. Recipient-derived cells were detected by short-tandem repeat-based genotyping. In cases with gender-mismatched transplantation, chimerism was semiquantitatively evaluated by in situ hybridization for the Y-chromosome. Findings were correlated to different pathomechanisms of epithelial injury as well as to morphologic and clinical outcome. Epithelial chimerism was detectable as early as 8 d after transplantation and lasted for 8 yr. A total of 88% of the patients showed an epithelial chimerism; 72% had a stable chimerism in sequential biopsy samples. Evaluation of Y-chromosome by in situ hybridization revealed low percentages of chimerical tubular epithelial cells (2.4% to 6.6%). No correlation to morphology was found. Chimerism was detectable in inconspicuous protocol biopsy samples, cases of drug toxicity, and rejected allografts with and without chronic changes. No correlation was found to allograft function. Epithelial microchimerism is an early and persistent phenomenon after renal transplantation. There is no correlation to morphologic or functional outcome. Probably recipient-derived stem cells contribute in a minor fashion to tissue homeostasis, and cell turnover in renal allografts is predominantly enabled by donor cell renewal.

Chimerism on the parenchymal level has been shown for several human allografts, including liver, heart, and kidney, with the integrated recipient-derived cells most likely originating from multipotent bone marrow precursors. We investigated whether chimerism also occurs within epithelial structures of the lung. For this purpose archival tissue biopsies from seven explanted human lung allografts were obtained. We performed laser microdissection of the target structures with subsequent short tandem repeat analysis to detect chimerism within the isolated cells. We found integration of recipient-derived cells in the bronchial epithelium, in type II pneumocytes and in seromucous glands lying adjacent to larger bronchi in all lung allografts studied. Quantitative analysis revealed that the epithelial structures displaying signs of chronic injury, such as squamous metaplasia, showed a markedly higher degree of chimerism (24% versus 9.5%). We therefore conclude that in human lungs, epithelial chimerism occurs at least within bronchi, type II pneumocytes, and seromucous peribronchial glands. Although a bone marrow origin of immigrating host-derived stem cells has been suggested by previous studies in rodents, analysis of lung biopsies from bone marrow-transplanted patients (n = 3) could not prove such delineation in this study. The observation of an enhanced integration of recipient cells into chronically damaged epithelial structures suggests that extrapulmonary precursor cells are able to contribute to pulmonary regeneration.