Shigeki Arii

Predictive value of vascular endothelial growth factor (VEGF) in metastasis and prognosis of human colorectal cancer

Vascular endothelial growth factor (VEGF) may affect the phenotype of cancer cells, such as growth velocity and metastatic potential, due to its probable multifunctional property including a mitogenic activity for vascular endothelial cells. The present study was designed to investigate the association of VEGF mRNA expression with progression and metastasis of human colorectal cancer. The level of VEGF mRNA expression was quantified by Northern blot hybridization in tumorous and non-tumorous tissues obtained from 60 primary colorectal cancer patients. The ratio of the former to the latter was defined as the VEGF T/N ratio, and the prognostic significance of this ratio, following surgery, in addition to the relationship to progression and metastatic potential, was evaluated. The value of the VEGF T/N ratio was significantly correlated with the depth of tumour infiltration (P=0.046), the incidence of liver metastasis (P < 0.0001) and lymph node metastasis (P=0.036). Patient prognosis was estimated by the Kaplan-Meier method and the log-rank test. When the VEGF T/N ratio was higher than 4.8 for which the chi2 value of the log-rank test was maximal, the tumour was defined as showing overexpression of VEGF mRNA. Patients with overexpression of VEGF mRNA demonstrated poorer survival than patients without overexpression of VEGF mRNA (P < 0.001). The overall estimated hazard ratio for death in patients with overexpression of VEGF mRNA was 1.94 according to a multivariate analysis (P=0.005). Thus, VEGF is associated with the progression, invasion and metastasis of colorectal cancer, and overexpression of VEGF mRNA in the primary tumour is assumed to be closely correlated with poor prognosis in colorectal cancer patients. Moreover, the VEGF T/N ratio may be used as an independent prognostic marker in colorectal cancer patients.

Overexpression of the rhoC gene correlates with progression of ductal adenocarcinoma of the pancreas.

It has been reported that the rho genes, which consist of a ras-related small GTPase protein family, regulate cytoskeletal structures and have the potential to transform cultured cells. To investigate the biological relevance of the rho genes in pancreatic carcinogenesis, we examined expressions of the rhoA, B and C genes by polymerase chain reaction after reverse transcription (RT-PCR) in 33 cases of ductal adenocarcinoma of the pancreas. In addition, mutations of the K-ras, rhoA, B and C genes were studied in the same series of tumour tissues to correlate with rho gene expressions. The expression levels of the rhoC gene were significantly higher in tumours than in non-malignant portions (P < 0.001). Metastatic lesions overexpressed the rhoC gene compared with primary tumours (P < 0.05). Carcinoma tissues with perineural invasion and lymph node metastasis exhibited significantly higher expressions of the rhoC gene than tumours without these manifestations (P < 0.001 and P < 0.05 respectively). Overexpression of the rhoC gene significantly correlated with poorer prognosis of patients with pancreatic adenocarcinoma (P < 0.05). In contrast, the expression levels of the rhoA and B genes showed no significant relationship with clinicopathological findings. Mutation was not found either in the rhoA, B or C gene sequences examined. K-ras gene mutation, detected in 27 out of 33 (81.8%) cases, did not affect the expression levels in any of the rho genes. These suggest that elevated expression of the rhoC gene may be involved in the progression of pancreatic carcinoma independent of K-ras gene activation.

Reduced stability of retinoblastoma protein by gankyrin, an oncogenic ankyrin-repeat protein overexpressed in hepatomas.

Hepatocellular carcinoma (HCC) is one of the most common cancers in Asia and Africa, where hepatitis virus infection and exposure to specific liver carcinogens are prevalent. Although inactivation of some tumor suppressor genes such as p53 and p16INK4Ahas been identified, no known oncogene is commonly activated in hepatocellular carcinomas. Here we have isolated genes overexpressed in hepatocellular carcinomas by cDNA subtractive hybridization, and identified an oncoprotein consisting of six ankyrin repeats (gankyrin). The expression of gankyrin was increased in all 34 hepatocellular carcinomas studied. Gankyrin induced anchorage-independent growth and tumorigenicity in NIH/3T3 cells. Gankyrin bound to the product of the retinoblastoma gene (RB1), increasing its phosphorylation and releasing the activity of the transcription factor E2F-1. Gankyrin accelerated the degradation of RB1 in vitro and in vivo, and was identical to or interacted with a subunit of the 26S proteasome. These results demonstrate the importance of ubiquitin–proteasome pathway in the regulation of cell growth and oncogenic transformation, and indicate that gankyrin overexpression contributes to hepatocarcinogenesis by destabilizing RB1.

Predictive factors for intrahepatic recurrence of hepatocellular carcinoma after partial hepatectomy.

To establish useful predictors of the intrahepatic recurrence of hepatocellular carcinoma (HCC) after partial hepatectomy, retrospective analyses of clinical and pathologic factors were done in 112 of 206 patients treated by partial hepatectomy. The absence or presence of intrahepatic recurrence was confirmed by a follow‐up study. Cancer‐free survival rates after 1, 2, 3, and 5 years were 54.8%, 36.7%, 32.5%, and 25.6%, respectively. The significant factors affecting recurrence were tumor size, number of tumors, cancer cell infiltration of the fibrous capsule of the tumor, portal involvement, and stage of the tumor, but the grade of anaplasia according to Edmondson‐Steiners classification and the severity of associated liver cirrhosis did not show a correlation with the incidence of recurrence. According to Akaikes Information Criteria (AIC), tumor number is useful for predicting early prognosis, and capsular infiltration is a good indicator of long‐term survival. However, portal involvement gives much prognostic information throughout the entire postoperative period. Cancer 1992; 69:913–919.

Involvement of matrix metalloproteinase‐2 activity in invasion and metastasis of pancreatic carcinoma

Activation of matrix metalloproteinase‐2 (MMP‐2) has been implicated in the progression, invasion, and metastasis of various cancers, but little information is available with regard to its role in pancreatic carcinoma with poor prognosis.

A Prospective Randomized Trial of the Preventive Effect of Pre‐operative Transcatheter Arterial Embolization against Recurrence of Hepatocellular Carcinoma

To clarify whether pre‐operalive transcatheter arterial embolization (TAE) improves survival after hepatectomy, a prospective randomized comparative study was done. Of a total of 115 registered patients having solitary hepatocellular carcinoma (HCC) 2 to 5 cm in diameter, 18 (15.7%) were excluded after randomization. As a result, 97 patients were chosen as subjects and divided into two groups: hepatectomy with (group A: n = 50) and without (group B: n=47) pre‐operative TAE. The period of observation of the patients who survived the surgery was between 4.0 and 6.6 years. The randomization appeared to have provided well‐balanced groups of patients and the clinico‐pathological characteristics of the two groups were quite similar. The necrotic part of the cancerous lesions, as confirmed by operative specimens, amounted to 74.8 ±33.4% (mean±SD) in group A and 6.8 ±7.2% in group B (P<0.01). However, the cancer‐free survival rates after hepatectomy in both groups showed little difference (39.1±7.0 (%±SE) and 31.1±0.1, respectively). We speculate that TAE is not effective against such HCC accessory lesions as minute intrahepatic metastasis and tumor thrombus and that pre‐operative TAE does not improve post‐operative survival.

Tissue factor expression in human colorectal carcinoma

It has been suggested that tissue factor (TF) plays an important role in tumor metastasis. Its expression in sarcoma cells was reported to up‐regulate the vascular endothelial growth factor (VEGF) gene and thereby enhance tumor angiogenesis, which is essential to tumor metastasis. Although many malignant tumors have been reported to express this protein constitutively, recent clinical studies have focused mainly on the correlations among TF expression, tumor progression, and histologic grade. Therefore, to address the role of TF and the underlying mechanism of hematogenous metastasis of colorectal carcinoma, the authors analyzed the correlations among TF expression, hepatic metastasis, and VEGF gene expression in surgical specimens. Furthermore, they analyzed the prognostic significance of TF expression with respect to overall patient survival.

Identification of a neutrophil gelatinase-associated lipocalin mRNA in human pancreatic cancers using a modified signal sequence trap method

To identify the intercellular signal-transducing proteins and receptors produced by cancer cells, we attempted to clone cDNAs encoding secreted and type I membrane proteins using a signal sequence trap (SST) method with some modifications. By screening an SST library derived from pancreatic cancer cells, we identified two secretory proteins (neutrophil gelatinase-associated lipocalin (NGAL) and lung surfactant protein D) and three membrane proteins (carcinoembryonic antigen, BiP/GRP78 and Hsa4 mitochondrion cytochrome oxidase subunit II). NGAL mRNA was expressed in eight of the pancreatic cancer cell lines and eight pancreatic cancer tissues. The expression of NGAL mRNA was also observed in colorectal and hepatic tumors.

Results of surgical treatment for recurrent hepatocellular carcinoma; comparison of outcome among patients with multicentric carcinogenesis, intrahepatic metastasis, and extrahepatic recurrence

No consensus has been reached on the indications for and effectiveness of surgery for secondary intrahepatic hepatocellular carcinoma (HCC) and extrahepatic metastasis after macroscopically complete removal of primary HCC. Secondary intrahepatic HCCs, usually regarded as recurrence are classified into those arising as a result of multicentric carcinogenesis or intrahepatic metastases derived from the primary HCC. The present study was designed to evaluate the utility of surgical treatment in relation to the pathogenesis of the secondary HCC: classified as multicentric carcinogenesis (MC), intrahepatic metastasis (IM), and extrahepatic metastasis. Thirty patients underwent extirpation of secondary HCC: 22 patients had secondary HCCs in the remnant liver (MC group; n = 8; IM group, n = 14), 6 patients had extrahepatic metastases, and 2 patients had both intrahepatic and extrahepatic metastases. Survival rates after the re-resection in the 22 patients with the secondary intrahepatic HCCs were 94.7% at 1 year, and 50.2% at 3 years postoperatively, and the 8 patients with extrahepatic metastasis had survival rates of 62.5% at 1 year, 37.5% at 3 years, and at 5 years. The survival rates after re-resection in the MC group were 100% at 1 year and 80.0% at 3 years, whereas those in the IM group were 91.7% at 1 year, and 38.1% at 3 years. Surgery can be indicated not only in patients with localized intrahepatic secondary HCCs but also in those with extrahepatic metastasis. In particular, patients with secondary HCCs arising as a result of multicentric carcinogenesis are expected to have a good prognosis.

Implication of vascular endothelial growth factor and p53 status for angiogenesis in noninvasive colorectal carcinoma

It still is unclear when angiogenic potential, which is believed to be a prerequisite for tumor development, is acquired. The current study was designed 1) to clarify when the phenotypic change of angiogenicity occurs during the development of colon carcinoma and 2) to investigate the possible roles of vascular endothelial growth factor (VEGF) and p53 in angiogenesis.