farnesylamine and Pancreatic-Neoplasms

We have previously shown that farnesylamine which acts as a farnesyltransferase inhibitor (FTI) induces apoptosis in human pancreatic cancer cells. Since the effect of FTI is usually known as "cytostatic", another apoptotic machinery of farnesylamine should be revealed in addition to the inhibition of farnesylation. Considering the chemical formula of farnesylamine, the "long-chain fatty amine (LFA)" structure may have a critical role in this mechanism. In this experiment, we examined the cytotoxic effect of LFA with alkyl-chain including oleylamine. Exposure of human pancreatic cancer cells to LFAs resulted in cell death, whereas short-chain fatty amine and oleylamine-related compounds without "amine" did not exert cytotoxicity. Oleylamine-induced cell death was confirmed as apoptosis by DNA laddering and caspase-dependent, but numerous cytoplasmic vacuoles, a typical feature of autophagy (type-2 cell death), were also observed. Preceding the apoptosis, strong and sustained activation of c-jun N-terminal kinase (JNK) and p38 was observed; caspase inhibitors did not attenuate activities of those kinases despite significant inhibition of apoptosis. Blockage of JNK activity by dominant-negative mutant completely abrogated the oleylamine-induced DNA laddering, but not autophagy. Furthermore, oleylamine decreased extracellular signal-regulated kinase (ERK) activity, probably through the activation of mitogen-activated protein kinase phosphatase-1. Taken together, LFA induces apoptosis through activation of JNK, p38 and caspase, accompanied with ERK inactivation, in human pancreatic cancer cells.

Topics: Amines; Apoptosis; Enzyme Inhibitors; Farnesol; Humans; JNK Mitogen-Activated Protein Kinases; MAP Kinase Kinase 4; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Pancreatic Neoplasms; Tumor Cells, Cultured

Farnesyltransferase inhibitors (FTIs) represent a novel class of anticancer drugs and are now in clinical trial. We have previously shown that farnesylamine, synthetic isoprenoid-linked with "amine" which acts as a potent FTI, induces apoptosis in human pancreatic cancer cells through the ras signaling cascade. Since the effect of FTI is usually "cytostatic" rather than "cytotoxic", we speculated another apoptotic machinery of farnesylamine in addition to the effect of FTI. Farnesylamine induced sustained activation of c-jun N-terminal kinase (JNK), which was not caused by other FTI, FTI-277. Blockage of JNK activity by dominant-negative mutant abrogated the DNA laddering and significantly reduced "cytotoxic" effect of farnesylamine. Strikingly similar effect on JNK activation and apoptosis was induced by structurally related long-chain fatty amine (LFA), oleylamine, but not by farnesol, an isoprenoid analogue of farnesylamine without "amine." Taken together, apoptosis induction through JNK activation by farnesylamine based on the LFA structure rather than an effect of FTI.

Topics: Alkyl and Aryl Transferases; Amines; Antineoplastic Agents; Apoptosis; Enzyme Inhibitors; Farnesol; Farnesyltranstransferase; Genes, ras; Humans; JNK Mitogen-Activated Protein Kinases; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase 8; Mitogen-Activated Protein Kinases; Mutation; Pancreatic Neoplasms; Tumor Cells, Cultured

Farnesyl protein transferase (FPTase) catalyses the post-translational modification of proteins by a farnesyl pyrophosphate. One of the substrates of this enzyme is p21ras, the product of the ras oncogene. We examined whether farnesylamine, one of the FPTase inhibitors (FTI), is selectively cytotoxic in pancreatic carcinoma cells and Ki-ras-transformed fibroblasts. Furthermore, we investigated whether the cytotoxicity of farnesylamine is caused by the induction of apoptosis in these cells. Using the FPTase assay, we found that farnesylamine inhibited FPTase in vitro. Immunoprecipitation showed that farnesylamine inhibited farnesylation of p21ras in vivo. In addition, 24 and 5 microM farnesylamine were required to achieve 50% cytotoxicity in pancreatic carcinoma cells containing activated Ki-ras and Ki-ras-transformed NIH/3T3 cells, respectively. The parental NIH/3T3 cells were resistant to the cytotoxic effect of farnesylamine at concentrations less than 100 microM. After incubation with farnesylamine, DNA fragmentation was observed in both pancreatic carcinoma cells and Ki-ras-transformed fibroblasts at cytotoxic doses of this compound but not in NIH/3T3 cells. These results indicate that the mechanism of cell death induced by farnesylamine is apoptosis, and this apoptosis occurred specifically in pancreatic carcinoma cells containing mutated Ki-ras and the Ki-ras-transformed cells. Because raf is downstream of ras (p21ras) in the ras-raf-mitogen-activated protein kinase signaling pathway, we used c-raf-1-transformed fibroblasts, which proved to be resistant to apoptosis induced by farnesylamine. This supports the theory that inhibition of ras signaling may be related to the induction of apoptosis. These data further suggest that farnesylamine could be useful as a chemotherapeutic agent in cancers that very frequently contain a Ki-ras oncogene mutation, e.g., pancreatic cancer.

Topics: 3T3 Cells; Alkyl and Aryl Transferases; Animals; Apoptosis; Cell Transformation, Neoplastic; DNA Fragmentation; Enzyme Inhibitors; Farnesol; Genes, ras; Mice; Pancreatic Neoplasms; Protein Prenylation; Proto-Oncogene Proteins p21(ras); Signal Transduction