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Biomedical subjects

Marcus Kremer

Publications and source records attributed to Marcus Kremer.

23 records · Page 2Linked to original sources
PubMed2002

Busulfan depletes neutrophils and delays accelerated acute rejection of discordant xenografts in the guinea pig-to-rat model.

Complement factor C6 plays a critical role in mediating hyperacute rejection of discordant xenografts. In order to explore the mechanism of discordant xenograft rejection, we investigated kinetics and phenotypes of the cellular infiltrate in xenografts in untreated and leukocyte-depleted recipients, in relation to graft survival. Guinea pig cardiac xenografts were heterotopically transplanted to totally C6-deficient PVG (C-) rats. Grafts were removed after 0, 6, 12, and 24 h ( n = 6). Histological evaluation was performed with hematoxylin and eosin (H & E) and immunoperoxidase staining. The agents fucoidin and busulfan were applied to delay xenograft rejection further. Within 6 h, minimal perivascular edema with isolated infiltrating CD11b/c- and ED1-positive cells were found. An intense infiltration of CD11b/c- and ED1-positive cells with interstitial hemorrhage was present after 24 h, though with little CD161 and CD3 cell infiltration. Inhibition of cell adhesion by fucoidin did not prolong xenograft survival (34 +/- 15 h, n = 4, P<0.47), but the depletion of granulocytes by injection of busulfan did prolong survival of the discordant xenografts, to 62 +/- 22 h ( n = 7, P < or = 0.0039). These results demonstrate a significant effect of specific depletion of granulocytes and macrophages by busulfan therapy on guinea pig cardiac xenograft survival in PVG (C-) rats, suggesting the participation of these infiltrating cells in the xenoreactive rejection process.

Acute Disease↗
PubMed2002

Two novel tumor suppressor gene loci on chromosome 6q and 15q in human osteosarcoma identified through comparative study of allelic imbalances in mouse and man.

We have performed a comparative study of allelic imbalances in human and murine osteosarcomas to identify genetic changes critical for osteosarcomagenesis. Two adjacent but discrete loci on mouse chromosome 9 were found to show high levels of allelic imbalance in radiation-induced osteosarcomas arising in (BALB/cxCBA/CA) F1 hybrid mice. The syntenic human chromosomal regions were investigated in 42 sporadic human osteosarcomas. For the distal locus (OSS1) on mouse chromosome 9 the syntenic human locus was identified on chromosome 6q14 and showed allelic imbalance in 77% of the cases. Comparison between the human and mouse syntenic regions narrowed the locus down to a 4 Mbp fragment flanked by the marker genes ME1 and SCL35A1. For the proximal locus (OSS2) on mouse chromosome 9, a candidate human locus was mapped to chromosome 15q21 in a region showing allelic imbalance in 58% of human osteosarcomas. We have used a combination of synteny and microsatellite mapping to identify two potential osteosarcoma suppressor gene loci. This strategy represents a powerful tool for the identification of new genes important for the formation of human tumors.

Alleles↗
PubMed2002

Identification of cyclin D1 mRNA overexpression in B-cell neoplasias by real-time reverse transcription-PCR of microdissected paraffin sections.

PURPOSE: Overexpression of cyclin D1 mRNA and protein as a result of the chromosomal translocation t(11;14)(q13;q32) is a highly specific molecular marker of mantle cell lymphoma, but cyclin D1 dysregulation can also be found in other B-cell neoplasias. The aim of the study was to develop a precise and reliable tool for quantitation of cyclin D1 mRNA suitable for archival clinical specimens. EXPERIMENTAL DESIGN: A real-time reverse transcription-PCR (RT-PCR) assay was used to quantitate cyclin D1 mRNA copy numbers. Using 2000 microdissected cells as template, 104 formalin-fixed, paraffin-embedded lymph node, spleen, and decalcified bone marrow biopsies from a panel of 95 cases of B-cell non-Hodgkin's lymphomas (B-NHLs) were analyzed. In addition, cyclin D1 protein expression was assessed by immunohistochemistry. RESULTS: Strong cyclin D1 mRNA overexpression was detected in mantle cell lymphomas (23 of 23), hairy cell leukemias (5 of 19), and multiple myelomas (7 of 23) with particularly high levels in 2 of the latter cases. Intermediate transcript levels were found in 5 of 23 multiple myelomas and 7 of 19 hairy cell leukemias. B-cell chronic lymphocytic leukemias (10 of 10), follicular lymphomas (9 of 9), mucosa-associated lymphoid tissue lymphomas (5 of 5) and reactive lymphoid tissues with the exception of normal spleen had no or very low cyclin D1 expression. In comparison with real-time RT-PCR, immunohistochemistry showed a lower level of sensitivity, more variability, and did not allow accurate quantitation. CONCLUSIONS: Real-time RT-PCR for cyclin D1 mRNA is an excellent tool for the differential diagnosis of B-NHLs and, in combination with microdissection, a powerful approach for retrospective trials using archival clinical specimens as tissue source. Furthermore, real-time RT-PCR may help to identify subgroups of B-NHLs according to cyclin D1 mRNA copy numbers and to investigate the possible influence of different chromosomal breakpoints on cyclin D1 expression.

Chromosomes, Human, Pair 11↗
PubMed2002

Antitumor activity of UCN-01 in carcinomas of the head and neck is associated with altered expression of cyclin D3 and p27(KIP1).

Altered and deregulated cyclin-dependent kinase (cdk) activity is now believed to play a major role in the pathogenesis of head and neck squamous cell carcinomas (HNSCC), thus providing a suitable cellular target for therapeutic intervention. UCN-01 (7-hydroxy-staurosporine), a known protein kinase C and cdk modulator, demonstrates antiproliferative and antitumor properties in many experimental tumor models and may represent a potential candidate to test in HNSCC. In this study, UCN-01 displayed potent antiproliferative properties (IC50 of approximately 17-80 nM) in HNSCC cells. Cell cycle analysis revealed that UCN-01 treatment of HNSCC cells for 24 h leads to a G1 block with a concomitant loss of cells in S and G2-M and the emerging sub-G1 cell population, confirmed to be apoptotic by terminal deoxynucleotidyl transferase-mediated nick end labeling analysis. Additional in vitro studies demonstrated a G1 arrest that was preceded by depletion in cyclin D3, elevation of p21(WAF1) and p27(KIP1) leading to a loss in activity of G1 cdks (cdk2, cdk4), and reduction in pRb phosphorylation. Antitumor properties of UCN-01 were also assessed in vivo by treating HN12 xenografts (7.5 mg/kg/i.p./daily) with UCN-01 for 5 consecutive days. Total sustained abolition of tumor growth (P < 0.00001) was obtained with only one cycle of UCN-01 treatment. Terminal deoxynucleotidyl transferase-mediated nick end labeling staining of xenograft samples revealed a higher incidence of apoptosis in treated tissues when compared with control. Additional tissue analysis demonstrated that elevated p27(KIP1) with minimal increase in p21(WAF1) and reduced cyclin D3 levels were readily detected in those animals treated with UCN-01, similar to those observed in HNSCC cells. Thus, UCN-01 exhibits both in vitro and in vivo antitumor properties in HNSCC models, and these effects are associated with a decrease in cyclin D3 and an increase in p27(KIP1) protein levels, thus providing appropriate surrogate markers to follow treatment efficacy in vivo and, therefore, a suitable drug candidate for treating HNSCC patients.

3T3 Cells↗