Restoration of RUNX3 enhances transforming growth factor-beta-dependent p21 expression in a biliary tract cancer cell line.

RUNX3 is a candidate tumor suppressor gene localized in 1p36, a region commonly inactivated by deletion and methylation in various human tumors. To elucidate the role of RUNX3 in transforming growth factor (TGF)-beta signaling in biliary tract cancer, we transfected Mz-ChA-2 cells, which do not express RUNX3 but have intact TGF-beta type II receptor and SMAD4 genes, with the RUNX3 expression plasmid pcDNA3.1/RUNX3 or with the vector pcDNA3.1 as a control. Four Mz-ChA-2/RUNX3 clones and one control clone were obtained. Although TGF-beta1 only slightly inhibited growth of the control cells, growth inhibition and TGF-beta-dependent G(1) arrest were significantly enhanced in the RUNX3-transfected clones. None of the clones, however, exhibited apoptosis. The slightly increased TGF-beta1-induced p21 expression in the control clone was strongly enhanced in the RUNX3-transfected clones, and was accompanied by augmented decreases in the expression of cyclins D1 and E. When RUNX3 small interfering RNA was added, TGF-beta-dependent induction of p21 was reduced in the RUNX3-transfected clones. Xenografts of the clones in nude mice demonstrated that tumorigenicity was significantly decreased in the RUNX3-transfected clones in inverse proportion to the expression levels of RUNX3. Based on these results, RUNX3 is involved in TGF-beta-induced expression of p21 and the resulting induction of TGF-beta-dependent G(1) arrest.

Down-regulation of RUNX1, RUNX3 and CBFbeta in hepatocellular carcinomas in an early stage of hepatocarcinogenesis.

BACKGROUND: Our previous studies suggested that deficient function of RUNX3 protein is causally related to development and progression of human gastric cancer. RUNX3 is mapped to 1p36, which is frequently deleted in hepatocellular carcinomas (HCC), therefore, these tumors were investigated for expression and copy number changes of RUNX3 and other Runt-related genes, RUNX1, RUNX2, and their co-factor CBFP. Similarly nearby uninvolved liver showing cirrhosis or normal histology was investigated in conjunction with various clinicopathological factors. MATERIALS AND METHODS: Copy number change and expression change of RUNX family genes in 35 hepatocellular carcinoma specimens and adjoining liver with cirrhosis (LC) or normal histology were estimated using quantitative reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization.

Long-term survival of a case with multiple liver metastases from duodenal gastrointestinal stromal tumor drastically reduced by the treatment with imatinib and hepatectomy.

Constitutive activation of KIT receptor tyrosine kinase is a critical factor in the pathogenesis of gastrointestinal stromal tumors (GISTs). But there is little information on whether combination of imatinib mesylate (IM) and surgical treatment can prolong survival in the cases with unresectable multiple liver metastases. We report a case of postoperative recurrence of GIST treated by the tyrosine kinase inhibitor IM and surgical treatment. The initial complete response (CR) to treatment continued for 18 mo, but single liver metastasis showed regrowth in the left hepatic lobe during IM treatment. After partial resection of the recurrent tumor, postoperative course was uneventful and the patient has survived without recurrence for 24 mo. Currently, imatinib is the first-line therapy for non-resectable GISTs, but a single agent therapy often leads to tumor resistance. Even if tolerance to imatinib occurs, a combination of imatinib and surgical treatment can prolong survival in some cases as reported here. However, further studies on a large number of cases of recurrent GIST are necessary to evaluate the effectiveness of IM treatment combined with surgery.

Possible involvement of RUNX3 silencing in the peritoneal metastases of gastric cancers.

PURPOSE: Our previous results suggested that a lack of RUNX3 function contributed to human gastric carcinogenesis, but the role of RUNX3 in progression and metastasis remains unclear. We examined RUNX3 expression in clinical samples of peritoneal metastases in gastric cancers. Changes in metastatic potential were assessed in animal experiments using stable RUNX3 transfectants of gastric cancer cells. Finally, global expression changes were analyzed using a cDNA microarray. EXPERIMENTAL DESIGN AND RESULTS: Significant down-regulation of RUNX3 through methylation on the promoter region was observed in primary tumors (75%) as well as in all clinical peritoneal metastases of gastric cancers (100%) compared with normal gastric mucosa. Stable transfection of RUNX3 inhibited cell proliferation slightly, and modest transforming growth factor-beta (TGF-beta)-induced antiproliferative and apoptotic effects were observed. Interestingly, it strongly inhibited peritoneal metastases of gastric cancers in animal model (P < 0.01). Furthermore, we did globally analyzed expression profiles of approximately 21,000 genes in parent cells and stable transfectant of RUNX3 using a cDNA microarray. Microarray analysis identified approximately 28 candidate genes under the possible downstream control of RUNX3, some of these genes were considered to be possibly involved in peritoneal metastases, which were related to signal transduction (vav3, TOLL-like receptor, MAPKK, MET, S1 00A1 1, and cathepsin E), apoptosis (caspase 9), immune responses (CD55 and TLR1O), and cell adhesion (sialyltransferase 1 and galectin 4). Some of the genes are involved in the TGF-beta signaling pathway. CONCLUSION: These results indicate that silencing of RUNX3 affects expression of important genes involved in aspects of metastasis including cell adhesion, proliferation, apoptosis, and promoting the peritoneal metastasis of gastric cancer. Identification of such genes could suggest new therapeutic modalities and therapeutic targets.

Frequent downregulation of the runt domain transcription factors RUNX1, RUNX3 and their cofactor CBFB in gastric cancer.

Our previous studies suggest that lack of RUNX3 function is causally related to the genesis and progression of human gastric cancer, but potential roles of other members of the RUNX family genes have not yet been reported. We examined the expression of 3 Runt-related (RUNX) genes, RUNX1, RUNX2 and CBFB, in gastric cancer cell lines and primary gastric cancer specimens and compared them to those of RUNX3 reported earlier in conjunction with clinicopathologic factors. Expression of RUNX family genes in 9 gastric cancer cell lines, 56 primary gastric cancer specimens and surrounding normal gastric mucosa were estimated by Northern blot analysis, quantitative RT-PCR and in situ hybridization. Northern blot analysis in gastric cancer cell lines showed downregulation of RUNX1 and RUNX3 in 67% and 78% of the cell lines tested, respectively. The ratio of the average RUNX mRNA/beta-actin mRNA ratio (x10(3)) for RUNX1 was 48.0 +/- 21.1 vs. 21.4 +/- 8.1; RUNX2, 1.1 +/- 0.3 vs. 1.0 +/- 0.2; RUNX3, 9.2 +/- 6.3 vs. 3.1 +/- 1.3 and CBFB, 42.0 +/- 19.4 vs. 21.0 +/- 8.4 (normal vs. tumor, respectively, average +/-SD). The basal RUNX2 expression was very weak, and there was no significant change in gastric cancers. Both RUNX1 and RUNX3 showed remarkable downregulation in 62% and 69%, respectively, of surgically resected specimens compared to surrounding mucosa analyzed by quantitative RT-PCR (p < 0.01). Furthermore, CBFB, the gene encoding the cofactor of RUNX1, -2, -3, was also downregulated in significant fraction (32%, p < 0.05). The percentage of downregulation of RUNX1, RUNX3 and CBFB increased as the cancer stage progressed. Tricostatin A and 5'-azacitidin reactivate RUNX3 expression, but they could not reactivate expression of RUNX1 and CBFBeta in gastric cancer cells, suggesting that the downregulation was due to mechanisms other than methylation of the promoter region. These findings suggest that RUNX1 and CBFBeta in addition to RUNX3 play some roles in gastric cancers and that roles of RUNX gene family in gastric cancer are more widespread and complex than previously realized.

[Over expression of Reg IV in peritoneal dissemination of gastric cancer].

We previously performed a global analysis of the gene expression of gastric cancer cell lines established from peritoneal dissemination (SNU-5, SNU-16, SNU-719, KATO-III and GT3TKB) with the cDNA microarray method to identify the novel markers for the detection of micro-metastasis in peritoneal cavity. One of the up-regulated genes is Reg IV, which is a member of the Reg gene family belonging to calcium dependent lectin (C-type lectin) gene superfamily. We have examined Reg IV potential as a novel marker for the detection of peritoneal micro-metastases of gastric cancer. Reg IV expression was examined in five gastric cancer cell lines established from peritoneal dissemination and compared with myeloid leukemia cell (HL60), methothelial cell lines Met5A and the other gastric cell line established from primary tumor (SNU-1) by quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Reg IV was highly overexpressed in 4 gastric cancer cell lines established from peritoneal dissemination, but weakly expressed in other cell lines. According to Reg IV mRNA expression levels in surgically resected specimens, the quantity of Reg IV correlated with wall penetration. Furthermore, Reg IV mRNA expression level in the peritoneal wash from 35 gastric cancer patients was also prone to correlation with wall penetration. These results suggest that Reg IV may be involved in peritoneal dissemination of gastric cancers and Reg IV may be a potential novel marker for peritoneal dissemination of gastric cancers.

Possible involvement of inositol 1,4,5-trisphosphate receptor type 3 (IP3R3) in the peritoneal dissemination of gastric cancers.

Our previous study using cDNA microarray showed that differentially expressed genes among gastric cancer cells involved in peritoneal dissemination could be positively identified. One of these genes, which is overexpressed, is inositol 1,4,5-trisphosphate receptor type 3 (IP3R3). IP3R3 is responsible for the intracellular Ca2+ release channel and for mobilizing stored Ca2+. Three different receptor types have been molecularly cloned and their genes have been classified into a family. However, the role of the IP3 signaling pathway in the peritoneal dissemination of gastric cancer is still unclear. In the study presented here, the IP3R3 is showed to be overexpressed in gastric cancer cell lines established from malignant ascites, but weakly expressed in a gastric cancer cell line established from primary tumor as well as normal gastric epithelial cells. IP3R1 and 2 are only weakly or not expressed in these cells. The antagonist of IP3R, 2APB, inhibited cell proliferation and induced apoptosis in gastric cancer cells from malignant ascites at concentrations of 100 nM to 100 microM in a dose-dependent manner. On the other hand, 2APB showed a weak effect on other gastric cancer cells established from primary tumors (SNU1), lymph node metastases or liver metastases (MKN1 or 74), methothelial cell lines Met5A and myeloid leukemia HL60 cells. This suggests that this inhibitory effect depends on the level of IP3R3 expression. As cells which express IP3R3 mRNA (i.e. pancreas ascinar cells) are known to have a secretory function in which IP3/Ca2+ signaling has been shown to be involved, IP3R3 may be a prerequisite for secretion of an enzyme, such as protease, in gastric cancer cells. These results indicate that IP3R3 may be specifically involved in gastric cancer peritoneal dissemination and that IP3R3 may be a molecular target of the peritoneal dissemination of gastric cancer. Its antagonist, 2APB, may thus be useful for the specific treatment of peritoneal dissemination of gastric cancer.