Incremento en la expresión del ARNm del receptor c-Met en el cáncer gástrico / Increased expression of the c-Met receptor mRNA in gastric cancer

El cáncer gástrico es una de las patologías malignas más frecuentes en el mundo. En las últimas décadas la atención se ha centrado en posibles alteraciones de factores genéticos que incluyen la activación de proto-oncogenes y/o la inactivación de genes supresores tumorales. El producto del C-MET proto-oncogen y su ligando, el factor de crecimiento del hepatocito (HGF), han sido implicados en la proliferación y migración celular en el cáncer gástrico. En este estudio se analizó a nivel molecular la amplificación del ARNm del receptor c-Met a partir del tejido tumoral gástrico de pacientes a quienes se les practicó gastrectomías, utilizando el método del ácido guanidina-tiocianato-fenol-cloroformo, y el método semicuantitativo de la Reacción en Cadena de la Polimerasa con Transcriptasa Reversa (RT-PCR), encontrándose que los elevados niveles del ARNm del receptor c-Met en las muestras tumorales de los pacientes están relacionados con mayor invasión en la profundidad de la pared gástrica (r = 0,762, p<0,01), incremento en la metástasis a los ganglios linfáticos (r = 0,766, p<0,01), alta frecuencia en tumores pocos diferenciados o indiferenciados (r = 0,912, p<0,001), aumento en el estadiaje del cáncer gástrico (r = 0,838, p<0,001), y en la sobreexpresión por el método inmunohistoquímico (IHQ) de la estreptavidina-biotina marcada de su receptor a nivel proteico (r = 0,858, p<0,001). La amplificación del ARNm y/o la sobreexpresión a nivel proteico del receptor c-Met, pudieran ser utilizados como factores pronósticos en el cáncer gástrico.

Gastric cancer is one of the most common malignancies in the world. In the last decades, the attention has been focused in possible alterations of genetic factors that include proto-oncogene activation and/or the tumor suppressor gene inactivation. The product of the proto-oncogene c-MET and its ligand, hepatocyte growth factor (HGF), have been implicated in cell proliferation and migration in gastric cancer. In this study we analyzed at the molecular level, the amplification of c-Met receptor mRNA from gastric tumor tissue of patients who underwent gastrectomy, using the acid guanidinium-thiocyanate-phenol-chloroform method and the semiquantitative Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) method. It was found that high levels of c-Met receptor mRNA in tumor samples from patients are associated with greater depth of invasion in the gastric wall (r = 0.762, p<0.01), increase in metastases to lymph nodes (r = 0.766, p<0.01), high frequency of poorly differentiated or undifferentiated tumors (r = 0.912, p<0.001), increase in the gastric cancer staging (r = 0.838, p<0.001), and the overexpression, by the immunohistochemistry method (IHC) of the labeled streptavidin-biotin, of the c-Met receptor at the protein level (r = 0.858, p<0.001). The amplification of mRNA and/or protein level overexpression of the c-Met receptor could be used as prognostic factors in gastric cancer.

Role of HGF/c-Met in Serum-Starved ARPE-19 Cells

PURPOSE: Hepatocyte growth factor (HGF) and its receptor (HGFR/c-Met) regulate motility, mitogenesis, and morphogenesis in a cell type-dependent fashion. We report the role of HGF and c-Met on stress-induced ARPE-19 human retinal pigment epithelial (RPE) cells in this study. METHODS: The cells were cultured either with or without serum. Southern and Western blot analyses were done to determine the expression patterns of HGF/c-Met in serum-starved ARPE-19 cells. The cell proliferation pattern in serum-starved condition was analyzed using MTS assay. Inhibition level of cell proliferation was analyzed using a neutralizing monoclonal antibody against c-Met (2 microgram/ml). RESULTS: Abnormal cell proliferation and scattering of ARPE-19 cells was observed under serum starvation. HGF/c-Met were expressed in serum-starved ARPE-19 cells. ARPE-19 cell proliferation was also enhanced with recombinant HGF treatment. Neutralization against c-Met inhibited the proliferation of serum-deprived ARPE-19 by 64.5% (n=9, S.D. 5.5%). Serum starvation appears to induce epithelial-mesenchymal transition of ARPE-19 cells, resulting in scatter, and the expression of alpha-smooth muscle actin (alpha-SMA), a marker for fibrosis. CONCLUSIONS: In conclusion, c-Met induced under non-physiologic conditions has significant effects on the activation of RPE cells.