Noriyuki Okada

Immunohistochemical study of metallothionein in pancreatic carcinomas

Metallothioneins are a family of intracellular metalloproteins that have been thought to be involved in anticancer drug resistance. However, the role of metallothioneins in pancreatic cancer has not been investigated in detail The immunohistochemical localization of metallothionein was examined in normal human adult pancreas tissue and in 75 pancreatic duct cell carcinomas, using monoclonal anti-metallothionein antibody. Furthermore, in vitro studies on the sensitivity of pancreatic cancer to cisplatin were performed in 10 cases of pancreatic carcinoma. Metallothionein staining was wekly positive in the acinar and islet cells and intralobular ducts but was negative in the large pancreatic ducts. In pancreatic carcinomas, metallothionein staining was diffusely positive in 6 (8%), focally positive in 25 (33%) and negative in 44 (59%) of the 75 pancreatic carcinomas. The expression of metallothioneins in pancreatic tumors was related to metastasis, poor prognosis and poor histological grading (poorer glandular differentiation and nuclear anaplasia). The in vitro study of tumor sensitivity to cisplatin showed no significant correlation between metallothionein expression and resistance to cisplatin. Metallothionein-positive pancreatic carcinoma will be potentially highly malignant or acquire an enhanced ability to produce metallothioneins as the malignant potential increases. The expression of metallothionein could be a prognostic indicator in pancreatic carcinomas.

Clinical significance of serum p53 antigen in patients with pancreatic carcinomas.

BACKGROUND: Alterations in the p53 gene are often found in pancreatic cancer, and accumulation of the p53 protein has been noted in tumour cells. AIMS: To investigate whether serum p53 protein concentrations could be used as markers for p53 gene mutations in neoplasms of the pancreas. METHODS: Serum p53 protein concentrations were determined by an enzyme linked immunosorbent assay (ELISA) in 104 cases of pancreatic adenocarcinoma, and 61 matched formalin fixed tissue sections were also stained by an anti-p53 DO-7 monoclonal antibody. RESULTS: The mean serum concentration of p53 protein in the adenocarcinoma patients was 0.27 (SEM 0.02) ng/ml, and was significantly higher than in 35 healthy blood donors (0.15 (0.02) ng/ml, SD = 0.11) or in 15 cases of chronic pancreatitis (0.15 (0.02) ng/ml). Adopting an arbitrary cut off value for the serum p53 protein concentration of 0.37 ng/ml, which corresponded to a value 2 SD above the mean value from the healthy blood donors, positive serum p53 protein concentrations were found in 23 out of 104 (22.1%) patients with adenocarcinomas examined, 16 out of 47 (34.0%) patients with carcinomas with distant metastases, but only seven of 57 patients (12.3%) with carcinomas without metastases (p < 0.05). In 11 patients with pancreatic adenocarcinomas, the mean serum p53 protein concentration after tumour resection was 0.21 (0.05) ng/ml, and had decreased compared with the preoperative concentrations (0.25 (0.05) ng/ml) (P < 0.05). There were no significant associations between the serum concentrations of p53 protein and serum concentrations of markers such as CA19-9 or CEA; however, serum concentrations of p53 protein demonstrated a potential role as an additional tumour marker. Immunohistochemical studies disclosed that the p53 protein was expressed in 28 out of 61 pancreatic adenocarcinomas (45.9%). Serum p53 protein concentrations in the positively immunostained cases were significantly higher than in the negatively immunostained cases (0.35 (0.05) ng/ml v 0.15 (0.01) ng/ml; p < 0.005). Furthermore, positive immunostaining for p53 protein was found in eight out of 10 (80%) serum positive p53 protein cases with adenocarcinomas. CONCLUSION: An increase in serum p53 protein concentrations appears during the progression of pancreatic adenocarcinoma and correlates with the accumulation of p53 protein as a result of a mutation of the p53 gene. An analysis of p53 antigen concentrations can detect p53 gene alterations, which could be useful for the selection of treatment regimens.

Expression of membrane-type matrix metalloproteinase-1 in human pancreatic adenocarcinomas

Abstract The expression of a new type of matrix metalloproteinase, membrane-type matrix metalloproteinase-1 (MT-MMP-1), was examined in 24 cases of primary pancreatic adenocarcinomas and 9 cases of secondary liver tumors derived from pancreatic adenocarcinomas, using a non-radioactive in situ hybridization and immunohistochemical methods. Out of 24 cases of primary pancreatic adenocarcinomas, 18 showed positive expression of MT-MMP-1 transcripts in cancer cells and 20 of 24 showed positive expression in the tumor stromal cells. The immunoreactivity of the gene products for MT-MMP-1 was demonstrated to be almost the same, as shown by in situ hybridization in these 24 cases. In particular, both the staining intensity for MT-MMP-1 transcripts and the immunoreactivity of the gene products in the tumor stromal cells of mucinous cystadenocarcinomas were significantly weaker than those of common-type ductal adenocarcinomas among the 24 cases. All of the 9 cases of secondary liver tumors derived from pancreatic adenocarcinomas showed positive expression for MT-MMP-1 transcripts but less immunoreactivity for the gene products. These results suggest that MT-MMP-1 is transcribed and translated in both cancer cells and the tumor stromal cells in human pancreatic adenocarcinomas. Furthermore, considering that common-type ductal adenocarcinoma of the pancreas usually shows a strong desmoplastic reaction, while mucinous cystadenocarcinoma typically does not, MT-MMP-1 expressed in the tumor stromal cells of common-type adenocarcinomas may be involved in processes leading to the desmoplastic reaction.

Evaluation of cholecystokinin, gastrin, CCK-A receptor, and CCK-B/gastrin receptor gene expressions in gastric cancer

The brain-gut hormones, cholecystokinin (CCK) and gastrin, regulate the growth of gastrointestinal mucosa and tumor cells. In this study, reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate messenger RNA expression for CCK, gastrin, CCK-A receptor, and CCK-B/gastrin receptor in surgical specimens of gastric cancers and in normal antrum and body mucosa of the stomach. The CCK mRNA expression was detectable in 4/14 (29%) samples of gastric cancer and in 3/12 (25%) samples of antral mucosa. However, the gastrin mRNA expression was not detectable in any gastric cancer samples, although it was detectable in all the samples of antral mucosa. The CCK-A receptor mRNA expression was detectable in 5/14 (36%) samples of gastric cancer and in 7/12 (58%) body mucosa. Three cases out of 14 (21%) of gastric cancer expressed both CCK gene and CCK-A receptor gene. The CCK-B receptor mRNA expression was detectable in only 1/14 (7%) samples of gastric cancer, although it was detectable in 10/12 (83%) body mucosa of the stomach. These findings may suggest a greater role for CCK and CCK-A receptor than for gastrin and CCK-B receptor in gastric cancers.

Elevated Serum c-erbB-2 Protein Levels in Patients with Pancreatic Cancer: Correlation to Metastasis and Shorter Survival

Overexpression of the c-erbB-2 proto-oncogene has been shown to correlate with relapse and poor prognosis in adenocarcinomas of the breast and stomach. In pancreatic cancer, c-erbB-2 overexpression has been demonstrated using immunohistochemistry, but the relationship between serum c-erbB-2 level and clinical data has not been fully evaluated. In this study, serum c-erbB-2 protein levels were measured in 100 patients with pancreatic adenocarcinomas and in 9 patients with mucin-producing tumors. Immunohistochemical studies for c-erbB-2 protein were performed in 36 patients and 4.0 U/ml in healthy controls (p < 0.001). The positive rate for serum c-erbB-2 was 34% (37/109) in patients with pancreatic cancer and 0% (0/66) in patients with gallstones and in healthy controls (p < 0.001). Immunohistochemical study disclosed that the positive staining rate was 28% (8/29) in common ductal adenocarcinoma specimens, 43% (3/7) in metastasis specimens, and 75% (3/4) in mucin-producing tumor specimens. Clinical evaluation revealed that 59% (22/37) of serum c-erbB-2-positive patients and 33% (24/72) of negative patients had liver or peritoneal metastases (p < 0.01). The mean survival time was 154 days in the c-erbB-2-positive group and 220 days in the negative group (p < 0.05). We suppose that c-erbB-2 is related to metastasis and progression of the disease in patients with advanced pancreatic cancer.

Increased pancreatic metallothionein and glutathione levels: protecting against cerulein- and taurocholate-induced acute pancreatitis in rats.

&NA; Recent findings have suggested that oxygen-derived free radicals play an important role in the development and progression of acute pancreatitis. Therefore, the present study was designed to investigate whether metallothionein, a free radical scavenger, can protect against acute pancreatitis. Rats were injected intraperito-neally with zinc, followed by either an infusion of cerulein at 10 μg/kg for 4 h or a retrograde injection with 100 μ1/100 g body weight of 5% sodium taurocholate into the pancreaticobiliary duct, in order to induce acute pancreatitis. Zn administration significantly increased the levels of both metallothionein and reduced glutathione in the pancreas; the metallothionein levels reached a peak of 83-fold of normal levels after 24 h. The indications of acute pancreatitis, as well as the mortality, were improved by Zn treatment before the onset of acute pancreatitis. Immunohistochemical studies showed that metallothionein accumulated in the acini of the pancreas in the Zn-treated groups, and with strong staining around the periphery of the vacuoles in the group treated with both Zn and cerulein. These findings suggested that Zn increased both metallothionein and glutathione levels in the pancreas and exerted a beneficial effect against cerulein-or taurocholate-induced acute pancreatitis in rats.

Usefulness of selective arterial calcium injection test and secretin test in patients with insulinoma

Preoperatively, it is sometimes very difficult to localize pancreatic endocrine tumors by conventional imaging techniques. Insulinoma is often solitary and benign, but 10% of insulinomas are multiple and malignant. To perform a curative resection of insulinomas, it is important not to leave any tumor postoperatively. In patients with gastrinomas, the selective arterial secretin injection test has been demonstrated to be useful for the curative resection of gastrinomas, since this test tells us whether there is a gastrinoma in the area of interest. The principle of this test is based on the observation that gastrinomas promptly release gastrin when stimulated by secretin. Following a principle analogous to that underlying the secretin test, we have used calcium solution as a stimulant for insulinoma. This selective arterial calcium injection (SACI) test has been used in Kyoto and in National Institute in Health, Bethesda, USA, NIH since 1990. In three patients with insulinoma, curative resection was performed successfully, based on localization by the SACI test. For the differential diagnosis of insulinoma and B cell hyperplasia, we used the intravenous secretin test in 14 patients who had had episodes of hypoglycemia; the test was useful, showing 75% sensitivity and 100% specificity.

Response of human insulinoma cells to extracellular calcium is different from normal B cells.

The preoperative determination of thelocalization of a small insulinoma is sometimesdifficult using routine imaging techniques. We have usedthe selective arterial calcium injection (SACI) test todetermine the location of the tumor preoperatively. Thepathophysiologic basis of the SACI test is based on theresponsiveness of insulinomas to calcium injected intothe feeding artery. In this study, we demonstrated the in vitro response of the insulinoma cellsto the extracellular calcium challenge by usingprimary-cultured insulinoma cells. Human insulinomacells were obtained from three patients. MIN6 cells(normal pancreatic B cells) were used as a control;their insulin response to various stimuli resembles thatof normal B cells. The insulin secretory dynamics inresponse to extracellular calcium were observed using a perfusion system. Second, the change ofthe concentration of cytosolic free calcium([Ca2+]i) was monitored byfluorometry using fura-2/AM. When the concentration ofextracellular calcium ([Ca2+]o) was changed from 2.54 mM to 10 mM, insulinsecretion from the insulinoma cells was markedlyincreased within 6 min (10- to 18-fold at maximum), andrapidly returned to the basal level; at the same time, [Ca2+]i was immediatelyelevated and reached a peak within 1 min. In contrast,in the MIN6 cells, the insulin secretion and [Ca2+]iwere not significantly changed when[Ca2+]o was switched to 10 mM. The results of these in vitro experiments agreedwith the clinical results of the SACI test. The positiveresponse of the insulinoma to the SACI test is probablydue to the different response of insulinoma cells to the extracellular calcium challengecompared with normal B cells. The role of[Ca2+]i may be important in themechanism underlying the SACI test.

Exocrine pancreatic function in the early period after pancreatoduodenectomy and effects of preoperative pancreatic duct obstruction

Exocrine pancreatic function in the early period after pancreatoduodenectomy was investigated. The effects of preoperative pancreatic duct obstruction on exocrine pancreatic function were also investigated. The volume of pancreatic juice and its amylase activity were investigated in 39 patients who underwent pancreatoduodenectomy (including pylorus-preserving pancreatoduodenectomy). TheN-benzoyl-l-tyrosyl-p-aminobenzoic acid (BT-PABA) test was performed on 23 of 39 patients about 40 days after pancreatoduodenectomy. The exocrine pancreatic function was inhibited three to eight days after pancreatoduodenectomy (amylase activity: 23,700±4300 IU/day), and recovered on days 9–15 (48,000±8400 IU/day) in patients with a normal main pancreatic duct. In patients with pancreatic duct obstruction, the exocrine pancreatic function was almost eliminated (amylase activity: 440±260 IU/day) and BT-PABA test results were low (45±17%). In patients with narrowed pancreatic duct, amylase secretion was significantly inhibited even in patients with a normal number of acinar cells. There was a good positive correlation (Spearmans rank correlation coefficient,rs=0.715,P<0.01) between amylase secretion and BT-PABA test. Amylase secretion more than 10,000 IU/day is essential for a normal BT-PABA test and normal digestive function. The inhibited digestive function in patients with pancreatic duct obstruction may be due to the decreased number of acinar cells and the inhibition of exocrine pancreatic function.

Pancreatic Exocrine Secretion in Short-Term Pancreatic Duct Obstruction Induced Acute Pancreatitis in Rats: An in vivo and in vitro Study

We investigated digestive enzyme release following a short-term pancreatic duct obstruction in rats. An in vivo experiment demonstrated that a 6-hour pancreatic duct obstruction reduced digestive enzyme release evoked both by endogenously released cholecystokinin (CCK) due to pancreaticobiliary diversion and by exogenous administration of CCK8. In vitro experiments also showed that pancreatic duct obstruction reduced the maximal CCK8-evoked amylase secretion. Amylase secretion evoked by the calcium ionophore A23187 and by phorbol myristate acetate was also markedly decreased. These data suggest that pancreatic duct obstruction probably interferes with the secretory process downstream of hormone receptor binding, intracellular Ca2+ release and protein kinase C activation.