Expression of CD24 in cholangiocarcinoma cells is associated with disease progression and reduced patient survival

Cholangiocarcinoma is frequently found to invade local tissues and metastasize to distal organs. We investigated the expression of CD24 in cholangiocarcinoma samples and its prognostic significance. In addition, the cellular function of CD24 was studied in the RMCCA1 cholangiocarcinoma cell line. High CD24 expression significantly correlated with lymph node metastasis and positive surgical margins in cholangiocarcinoma patients. Univariate and multivariate analyses further demonstrated that CD24 expression was significantly associated with the overall survival of these patients (p=0.007 and p=0.040, respectively). For in vitro studies, the magnetic-activated cell sorting (MACS) system was used to isolate CD24+ and CD24- cell populations from RMCCA1 cells. CD24+ RMCCA1 cells had increased chemoresistance, adhesion (p=0.004), motility (p<0.001), migration (p<0.001) and invasion (p<0.001) capabilities when compared to CD24- cells. The matrix metalloproteinase (MMP)-7 was significantly elevated in CD24+ RMCCA1 cells (p=0.01). We found that inhibition of CD24 using siRNA silencing significantly decreased the invasive capacity of RMCCA1 cells. Both clinical and in vitro studies suggest that expression of CD24 is associated with cholangiocarcinoma disease progression. CD24 may thus serve as a new target for directed molecular therapy of cholangiocarcinoma.     

Involvement of ERK1/2 in invasiveness and metastatic development of rat prostatic adenocarcinoma

Extracellular signal-regulated kinase (ERK) activation has been implicated in cell motility and invasion. In this study, we demonstrated that the steady-state levels of activated ERK1/2 correlated with the degree of invasiveness and metastatic potential of three Dunning cancer cell lines, originating from the same parental tumor. Inhibition of mitogen-activated protein kinase kinase 1 (MEK1), an upstream regulator of ERK1/2, with PD98059 resulted in a dose-dependent reduction of invasiveness with different IC50 values in the three Dunning cell lines. These results suggest that ERK is, at least in part, responsible for regulating invasiveness and may underlie the differences in the metastatic ability of the cell lines.     

Dependence of metastatic cancer cell invasion on MLCK-catalyzed phosphorylation of myosin regulatory light chain

The role of myosin phosphorylation by myosin light chain kinase (MLCK) in regulating the invasiveness of metastatic cancer cells was investigated using the Dunning rat prostatic adenocarcinoma cell line, Mat Ly Lu, and in vitro invasion assay. Treatment with MLCK inhibitors resulted in marked reduction of invasiveness, which was principally due to impaired cellular motility, whereas the ability to survive and proliferate, to adhere to matrix, and to secrete gelatinases were minimally affected.     

PD98059-inhibited invasion of Dunning rat prostate cancer cells involves suppression of motility but not MMP-2 or uPA secretion

Up-regulation of extracellular-regulated kinases 1/2 (ERK1/2) has been implicated in tumor progression and metastasis in many types of cancer. We have previously shown that ERK1/2 is necessary for invasiveness of Dunning rat prostatic adenocarcinoma cell lines in which levels of activated ERK1/2 correlate with the metastatic potential. Here, we further examined the biological effects of elevated ERK1/2 in the highly metastatic Dunning cell line, MLL, in which the abilities to invade and metastasize are enhanced relative to its progenitor strain. Inhibition of ERK1/2 activation by the MEK1 inhibitor, PD98059, dose-dependently reduced MLL cell invasiveness and motility with similar IC50 values. On the other hand, the abilities of MLL cells to adhere to the extracellular matrix, phosphorylate myosin regulatory light chain and secrete matrix-degrading enzymes, matrix metalloproteinase (MMP)-2 and urokinase plasminogen activator (uPA) were marginally, if at all, affected by PD98059 treatment. These data indicated that the inhibitory effect of PD98059 on the invasiveness of MLL cells was primarily due to the suppression of cell motility, and the up-regulation of ERK1/2 is, at least in part, responsible for the enhanced cellular motility and invasiveness of the MLL cells.     

NGAL knockdown by siRNA in human cholangiocarcinoma cells suppressed invasion by reducing NGAL/MMP-9 complex formation

We studied the role of Neutrophil Gelatinase-associated Lipocalin (NGAL, lipocalin 2) in regulating the invasiveness of a cholangiocarcinoma cell line, RMCCA-1. RMCCA-1 cells expressed multiple forms of 25, 40, 75 and 115/135 kDa NGAL which were detected in the conditioned medium, whereas only the 25 kDa form was detected in the cell lysates. NGAL expression was induced by serum deprivation. NGAL downregulation by siRNA suppressed NGAL mRNA and protein expression by about 70–80%, concommittant with a significant reduction of in vitro invasiveness, migration and pro-MMP-9 activity, but not cell proliferation. Suppression of pro-MMP-9 activity paralleled a reduction of NGAL/MMP-9 complex in the conditioned medium, although MMP-9 mRNA expression was unaffected. Our data suggest that NGAL promotes the invasiveness of the cholangiocarcinoma cells by forming complex with MMP-9, stabilizing its activity and rendering the cancer cells to be more invasive.     

Establishment and characterization of a cholangiocarcinoma cell line （RMCCA-1） from a Thai patient

INTRODUCTIONCholangiocarcinoma is a highly malignant epithelial neoplasm that arises within the intrahepatic and extrahepatic biliary tract[1].The pathogenesis of this disease has been strongly associated with chronic inflammation and cellular injury with…     

Anti-metastatic effects of curcusone B, a diterpene from Jatropha curcas

A new approach to cancer therapy in recent years has been to target the metastatic process. The anti-metastatic potential of curcusone B, a diterpene isolated from Jatropha curcas Linn. (Euphorbiaceae), a herbal plant that has been used in traditional folk medicine in many tropical countries, was investigated against 4 human cancer cell lines. Treatment with non-cytotoxic doses of curcusone B resulted in a strong reduction of in vitro invasion, motility and secretion of matrix-metalloproteinases (MMP) of the cancer cells, whereas the ability to adhere to a Matrigel-coated surface was variably sensitive to curcusone B treatment. Curcusone B, thus, effectively suppresses the metastatic processes at doses that are non-toxic to cells, which may be of therapeutic benefit for the treatment of metastatic cancers.