Hepatocyte growth factor (HGF) and its receptor MET play an important role in cancer growth and metastasis. Activation of MET elicit multiple cellular responses regulating cell survival, morphogenesis, adhesion, migration, breakdown of extracellular matrix (ECM) and angiogenesis. Numerous disorders related to deregulation of HGF-MET axis have been reported. Thus, new therapeutic agents targeting HGF-MET signaling have been sought. Here, we will present data describing the role of HGF-MET axis in growth and metastasis of tumor cells together with the recent approaches to block this axis.

In this study, geldanamycin (GA) was found to have an antiproliferative effect on both embryonal and alveolar rhabdomyosarcoma (RMS) cell lines. The maximum level of inhibition reached 80% for both embryonal and alveolar RMS. After GA treatment, cells also became apoptotic as judged by Annexin V-positive staining, activation of caspase-3 pathway and poly(ADP ribose) polymerase cleavage. GA was responsible for the arrest of RMS cells in both G1 and G2/M phases of the cell cycle. G1 blockade, however, was transient and was seen only in the first 24 h of GA treatment. RMS often gives distant metastases to various organs including bone marrow. RMS cells express high levels of MET receptor and respond to hepatocyte growth factor with increased motility. In our study, we found that GA decreased the level of MET expression and inhibited the chemotaxis of RMS cells toward the hepatocyte growth factor gradient. GA also blocked the homing of RMS cells into bone marrow of severe combined immune deficient mice. In all our experiments embryonal RMS cell lines were significantly more sensitive, and lower concentrations of GA were sufficient to block embryonal RMS cell proliferation, induce apoptosis and inhibit motility. Our data show that the HSP90 inhibitor GA has the potential to become a new drug in RMS treatment. It blocks RMS proliferation, decreases cell survival and inhibits motility of RMS cells.

OS is a variant of SCID characterized by generalized erythroderma, alopecia, eosinophilia, and elevated IgE levels. It is fatal unless treated with allogeneic HSCT, which is the only curative approach. However, treatment related complications and graft rejection are major obstacles to the success of treatment. In this report, we describe a patient with OS, complicated by prolonged cytomegalovirus infection, successfully treated by reduced intensity conditioning allogeneic HSCT from sibling donor.

The potential for multilineage differentiation together with the ability to expand in cultures are the reasons why Mesenchymal Stem Cells (MSC) are considered to be the population of stem cells for potential treatment for variety of disorders (e. g. Osteogenesis Imperfecta, Myocardium Infarction, GvHD). MSC are isolated from the bone marrow mononuclear cells (MNC) based on their adhesive properties. There have been few attempts to isolate MSC directly based on the expression of selected surface antigens, but these isolation strategies were not compared with “the gold standard” procedure which is still selection by plastic adherence. Nevertheless, it is obvious that a presence of different populations of cells “contaminating” MSC in adherent cell cultures (e.g., endothelial cells, macrophages, dendritic cells) may affect expansion of MSC. In this study we proposed new isolation strategies of bone marrow MSC based on RosetteSep Isolation Kit (Stem Cells Technologies Inc., Vancouver, Canada) and immunomagnetic isolation of CD105+ or CD271+ cell populations (Miltenyi Biotec, Germany). Four fractions of bone marrow mononuclear cells i) non-purified MNC, ii) MNC enriched in MSC by RosetteSep Isolation Kit, iii) sorted CD105+ and iv) sorted CD271+ cells were cultured for three passages. Subsequently, we evaluated i) number of CFU-F colonies, ii) expression of selected surface antigens (CD105, CD166, CD44, CD73, CD45, CD34), iii) in vitro osteogenic differentiation of expanded cells and iv) changes in the expression of genes related to osteogenesis (RQ-PCR). We found that the mean number of CFU-F colonies counted on the 9th day of culture was 26 (range 14,5–41,4), 49 (range 21,2–97,1), 105 (range 36,5–221) and 148 (range 55,3–211) per 107 MNC for non-purified MNC, MNC enriched in MSC by RosetteSep Isolation Kit, purified CD105+cells and purified CD271+cells, respectively. After 3rd passage the phenotype of cells was similar as we observed a comparable percentage of cells positive (over 90%) for CD105, CD166, CD44, CD73 and negative (below 5%) for CD45, CD34 surface antigens in all fractions. The RQ - PCR analysis of mRNA level of osteogenic (osteocalcin, PTHR, α1collagen), adipogenic (lipoprotein lipase, leptin, PPARγ2) and chondrogenic (aggrecan1) genes in all four populations revealed that MSC isolated by means of expression of 105 and CD271 antigens had higher level of mRNA for all assessed genes except for lipoprotein lipase and α1collagen prior to differentiation. After 30 days of osteogenic differentiation RQ - PCR analysis was repeated and compared with that before differentiation. We noticed an increased level of mRNA for osteocalcin and PTHR (markers of osteogenic differentiation) in all four populations, with the highest expression in MSC derived from non-purified MNC. However, this fraction had also the highest mRNA level of PPARγ2, lipoprotein lipase, and aggrecan genes (adipogenic and chondrogenic lineage respectively). Since the highest number of CFU-F was derived from purified CD105+ and CD271+ cells as well as these two populations seem to be the most homogenous based on RQ-PCR data, these cell fractions should be employed to expand most efficiently MSC for potential therapeutic purposes. Our data suggest that, non-MSC cells present in MNC and RosetteSep cultures may negatively affect both the expansion efficiency and differentiation along desired MSC lineage.

Silencing of a target-genes by small interfering RNA (siRNA) has emerged as a powerful new tool not only for basic research but also with potential therapeutic benefits. This paper demonstrates that optimal delivery strategy is crucial for effective target-gene silencing. Using lipofection, under defined conditions, we were able to markedly down-regulate expression of the selected genes involved in rhabdomyosarcoma metastasis: MET, CXCR4, LIFR and PAX3-FKHR.© Versita Warsaw and Springer-Verlag Berlin Heidelberg. Keywords: siRNA • Rhabdomyosarcoma • Lipofectamine 2000 • MET receptor • CXCR4 • LIFR • PAX3-FKHR