CELL SEPARATION AND GENE EXPRESSION ANALYSIS IN A TUMOR-STROMA INTERACTION MODEL

A novel technique for co-culturing and separating fibroblasts and carcinoma cells in a 2-D model of tumorstroma interaction is presented. The methodology is based on cell co-cultivation on an 1.35 μm thin membrane followed by rapid immunostaining and microdissection of the different cell compartments using a laser microdissection system (P.A.L.M. Microlaser Technologies AG, Germany). For identifying the tumor cell compartment, immunolabeling for a marker that is expressed only in epithelial tumor cells is performed. The RNA quality from the microdissected co-cultured cells was successfully proved by RT-PCR for a housekeeping gene transcript and for the laminin gamma 2 chain gene transcript used before in the tumor cell immunostaining. Laminin cDNA was amplificable only in tumor cells and not in the co-cultivated fibroblasts indicating no cell-cross-contamination during microdissection. Microdissected tumor and stroma cells from the presented membrane based co-culture model can be used for gene expression profiling and DNA based analysis in the investigation of tumor-stroma interactions

No Incidence of BRAF Mutations in Salivary Gland Carcinomas—Implications for Anti-EGFR Therapies

BRAF is the main effector of KRAS in the RAS-RAF-MAPK axis, a signaling pathway downstream of EGFR. The activation of this cascade is an important pathway in cancer development and is considered a key pathway for therapeutic molecules. Recent studies in metastatic colorectal cancer found that an oncogenic activation of BRAF by a point mutation in exon 15 (V600E) could bypass the EGFR-initiated signaling cascade with the effect that patients bearing the mutant BRAF allele are not likely to benefit from EGFR-targeted therapies. We designed an allele-specific PCR and screened 65 salivary gland carcinoma (SGC) of the main histopathological types for the BRAF V600E mutation. All 65 SGC in this cohort (100%) presented the BRAF wildtype. In a previous study, we found a KRAS wildtype in 98.5% of SGC. These findings imply that SGC rarely acquires mutations that result in a constitutive activation of the signaling cascade downstream of EGFR and this pleads in favor of further therapeutic trials with EGFR-targeting monoclonal antibodies

Regulator of G-protein signaling 5 (RGS5) protein: a novel marker of cancer vasculature elicited and sustained by the tumor’s proangiogenic microenvironment

We previously identified regulator of G-protein signaling 5 (RGS5) among several genes expressed by tumor-derived endothelial cells (EC). In this study, we provide the first in vivo/ex vivo evidence of RGS5 protein in the vasculature of ovarian carcinoma clinical specimens and its absence in human ovaries. Consistent with this, we show higher amounts of Rgs5 transcript in EC isolated from human cancers (as opposed to normal tissues) and demonstrate that expression is sustained by a milieu of factors typical of the proangiogenic tumor environment, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2). Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature. RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA). To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues. RGS5 expression by the cancer vasculature triggered and retained by the proangiogenic microenvironment supports its exploitation as a novel biomarker and opens the path to explore new possibilities of therapeutic intervention aimed at targeting tumor blood vessels

Determination of telomerase activity for differential analysis of multifocal renal cell carcinomas

Determination of telomerase activity for differential analysis of multifocal renal cell carcinomas. Secondary tumors are found in approximately 12 to 22% of all renal cell carcinoma, and their origin is currently unknown. To determine their potential for malignancy, we examined the telomerase activity of primary tumors and secondary lesions, and found that 86% of the lesions had an identical telomerase status as the related primary tumors, and thus probably share their malignancy potential