Improved diagnostics targeting c-MET in non-small cell lung cancer: expression, amplification and activation?

BACKGROUND

Several c-MET targeting inhibitory molecules have already shown promising results in the treatment of patients with Non-small Cell Lung Cancer (NSCLC). Combination of EGFR- and c-MET-specific molecules may overcome EGFR tyrosine kinase inhibitor (TKI) resistance. The aim of this study was to allow for the identification of patients who might benefit from TKI treatments targeting MET and to narrow in on the diagnostic assessment of MET.

METHODS

222 tumor tissues of patients with NSCLC were analyzed concerning c-MET expression and activation in terms of phosphorylation (Y1234/1235 and Y1349) using a microarray format employing immunohistochemistry (IHC). Furthermore, protein expression and MET activation was correlated with the amplification status by Fluorescence in Situ Hybridization (FISH).

RESULTS

Correlation was observed between phosphorylation of c-MET at Y1234/1235 and Y1349 (spearman correlation coefficient rs = 0.41; p < 0.0001). No significant correlation was shown between MET expression and phosphorylation (p > 0.05). c-MET gene amplification was detected in eight of 214 patients (3.7%). No significant association was observed between c-MET amplification, c-MET protein expression and phosphorylation.

CONCLUSION

Our data indicate, that neither expression of c-MET nor the gene amplification status might be the best way to select patients for MET targeting therapies, since no correlation with the activation status of MET was observed. We propose to take into account analyzing the phosphorylation status of MET by IHC to select patients for MET targeting therapies. Signaling of the receptor and the activation of downstream molecules might be more crucial for the benefit of therapeutics targeting MET receptor tyrosine kinases than expression levels alone.

Relations among glycemic control, circulating endothelial cells, nitric oxide, and flow mediated dilation in patients with type 2 diabetes mellitus

OBJECTIVES

Circulating endothelial cells (CEC) have been identified as a surrogate marker of endothelial dysfunction. The aim of this study was to determine the association of glycemic control with CEC and endothelial function in patients with type 2 diabetes mellitus (DM).

METHODS

We studied 30 patients with type 2 DM and 20 age and sex matched healthy controls (HC). Number of circulating endothelial cells was measured by flow cytometry. Endothelial function was studied by measuring flow mediated vasodilation (FMD%) in the brachial artery and serum level of nitric oxide (NO).

RESULTS

CEC count was significantly elevated in patients with DM, than HC (35.3±15.1 vs. 7.3±2.4, p<0.001) and in patients with HbA1c>7 than patients with HbA1c≤7 (47.4±5.5 vs. 19.5±5.7, p<0.001). FMD% and NO were lower in DM patients than HC (3.5±0.85 vs. 9.5±3.1, p<0.001 and 37.8±6.1 vs. 64.1±5.7, p<0.001 respectively). FMD% and NO were lower in patients with HbA1c>7 as compared to patients with HA1c≤7 (2.8±0.4 vs. 4.3±0.4, p<0.001 and 33.1±2.9 vs. 43.9±2.8, respectively, p<0.001). HbA1c correlated negatively with FMD% and NO levels and positively with CEC. CEC count correlated negatively with FMD% and NO. There was a significant positive correlation between CEC count and HBA1c (p<0.001 for all correlations).

CONCLUSION

CEC is associated with markers of endothelial dysfunction and disease control in patients with type 2 DM. These findings suggest a potential role of CEC in the pathophysiology of cardiovascular disease in type 2 diabetic and raise the importance of tight glycemic control.

Rapid identification of local T cell expansion in inflammatory organ diseases by flow cytometric T cell receptor Vbeta analysis

Oligoclonal expansion of antigen-specific T cells occurs frequently during inflammatory diseases. These cells may persist for a long time at high frequency in the body and be enriched in the affected tissues. As a screening test for expanded cell T cell populations at sites of inflammation, we developed an optimized methodology for flow-cytometry-based quantification of T cell receptor Vbeta (TCRBV) expression. We first validated the specificity of a TCRBV-specific monoclonal antibody set by direct comparison with PCR-based analysis of mono- and polyclonal T cell samples. This monoclonal antibody (mAb) panel recognized approximately two thirds of the T cell receptor alpha/beta repertoire in a group of 64 healthy donors and allowed defining TCR usage in the CD4+ and CD8+ subsets. The reliable detection of expanded Vbeta gene families in T cell populations was confirmed in experiments on superantigen-stimulated T cells. Through differential TCR analysis on T cell subpopulations in cerebrospinal fluid and blood in patients with acute encephalitis, we were able to identify locally expanded CD8+ T cells. The power of this approach affords not only high-throughput comparative TCR analysis for immunological studies in vitro, but also rapid ex vivo identification of cell populations enriched in organ compartments during inflammatory diseases.

A point mutation in PTPRC is associated with the development of multiple sclerosis

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. It is widely accepted that a dysregulated immune response against brain resident antigens is central to its yet unknown pathogenesis. Although there is evidence that the development of MS has a genetic component, specific genetic factors are largely unknown. Here we investigated the role of a point mutation in the gene (PTPRC) encoding protein-tyrosine phosphatase, receptor-type C (also known as CD45) in the heterozygous state in the development of MS. The nucleotide transition in exon 4 of the gene locus interferes with mRNA splicing and results in altered expression of CD45 isoforms on immune cells. In three of four independent case-control studies, we demonstrated an association of the mutation with MS. We found the PTPRC mutation to be linked to and associated with the disease in three MS nuclear families. In one additional family, we found the same variant CD45 phenotype, with an as-yet-unknown origin, among the members affected with MS. Our findings suggest an association of the mutation in PTPRC with the development of MS in some families.