Learning curve for the surgical time of laparoscopic cholecystectomy performed by surgical trainees using the three-port method: how many cases are needed for stabilization?

BACKGROUND

The assessment of laparoscopic cholecystectomy (LC) skills using operating times has not been well reported. We examined the total and partial operating times for LC procedures performed by surgical trainees to determine the required number of surgeries until the surgical time stabilizes.

METHODS

We reviewed the video records of 514 consecutive LCs using the three-port method, performed by 16 surgical trainees. The total and partial surgical times were calculated and correlated to the surgeons' experience.

RESULTS

The median total surgical time for a trainee's first LC was 112 (range 71-226) minutes. It reduced rapidly after the first 20 LCs and plateaued to its minimum after approximately 60 cases. A statistically significant time decrease was observed between the first 10 (median, range 112, 46-252 min) and the next 50-59 cases (64, 34-198 min), but not between the 50-59 and the subsequent 100-109 cases (71, 33-127 min). The total times taken by trainees who had performed > 50 operations were not significantly different from those taken by instructors during the study period. Surgery for 125 patients with acute cholecystitis took a significantly longer time (median 99 vs. 74 min with non-acute cholecystitis); however, the abovementioned time reduction findings showed similar results regardless of the patient's acute inflammation status. The partial operating times around the cervical/cystic duct and gallbladder bed reduced uniformly between the first 10 and the following 50-59 cases. Although time variations in total and cervical/cystic duct operating times were not correlated to the surgical experience, time fluctuation of gallbladder bed procedures reduced after 60 cases.

CONCLUSION

The time required to perform an LC was inversely correlated with the experience of surgical trainees and halved after the first 60 cases. The surgical experience required for LC time stabilization is approximately 60 cases.

[A Case of Suspected Lynch Syndrome Due to Radical Resection for Descending Colon Cancer and Renal Pelvic Cancer]

A 60-year-old woman was admitted on account of presenting with bloody stools. She had a history of endometrial cancer surgery. Family history revealed 3 colorectal cancer cases among the first or second relatives. Colonoscopy and contrast- enhanced computed tomography revealed descending colon cancer and left renal pelvic cancer. We performed partial resection of the descending/transverse colon with D3 lymph node dissection and total resection of the left kidney and ureter with curative intent. Postoperative pathological diagnosis revealed descending colon cancer(pT4bN0M1c, pStage Ⅳc)and left renal pelvic cancer (T1N0M0, Stage Ⅰ). In this case, Lynch syndrome was suspected based on the family history and medical history. The clinical findings were consistent with Amsterdam Criteria Ⅱ. The microsatellite instability(MSI)test result was MSI-H and the BRAF genetic test result showed a wild type. Immunohistochemical staining of descending colon cancer tissue showed loss of expression of MSH2 and MSH6 proteins. Genetic counseling was provided because Lynch syndrome was strongly suspected. Capecitabine plus oxaliplatin therapy was performed for 6 months for descending colon cancer. Nine months postoperatively, the patient remained recurrence-free for both colon cancer and renal pelvic cancer. We report a case of suspected Lynch syndrome triggered by double cancer of the descending colon and renal pelvis.

Laparoscopic transabdominal preperitoneal hernioplasty for bilateral obturator hernias and left inguinal hernia with emaciation caused by anorexia nervosa: A case report

A 55-year-old woman receiving treatment for anorexia nervosa presented with abdominal pain and right thigh pain. Her body mass index was 12.9 kg/m² . Computed tomography showed fluid storage in the distal side of the right obturator foramen and revealed a dilated small bowel without a starting point of obstruction. We diagnosed a naturally reduced incarcerated right obturator hernia and performed elective surgery with a laparoscopic approach for hernia repair the next day. Intraperitoneal observation revealed bilateral obturator hernias and a left direct-type inguinal hernia. Transabdominal preperitoneal hernioplasty was performed using two self-gripping polyester meshes for bilateral obturator hernia repair and a lightweight 3D-shaped mesh for left inguinal hernia repair. Women with emaciation caused by anorexia nervosa may be more likely to have complex hernias, including obturator hernia, and laparoscopic approaches may be useful for preoperatively diagnosed nonstrangulated obturator hernias.

Surgical approach for right-sided colonic diverticular bleeding: A single-center review of 43 consecutive cases

INTRODUCTION

While Asian populations develop colonic diverticular disease predominantly in the right colon, Western populations mainly present with left-sided disease. The present study aimed to clarify the outcomes of surgical treatment for right-sided colonic diverticular bleeding.

METHODS

Medical records of 43 patients who underwent surgery for right-sided colonic diverticular bleeding between 2010 and 2019 were reviewed. Those whose general condition became unstable underwent open surgery at our institution. Patients were then divided into two groups, the open surgery group (n = 17) and laparoscopic surgery group (n = 26), after which operative outcomes between both groups were compared.

RESULTS

This study included 36 men and seven women with a median age of 76 (range: 37-91) years. Laparoscopic surgery had a significantly longer operative time (183.5 minutes vs 110 minutes; P < .001) and significantly lower intraoperative blood transfusion rate (19.2% vs 82.4%; P < .001) than open surgery. The laparoscopic surgery group had earlier resumption of postoperative meals than open surgery group (postoperative day 3 vs postoperative day 4; P = .010). No significant difference in postoperative complications was observed between both groups. With regard to long-term outcomes, none of the cases exhibited rebleeding from the right-sided colon.

CONCLUSION

The present study revealed that laparoscopic surgery promoted lower intraoperative blood transfusion rates and earlier resumption of postoperative meals compared to open surgery for right-sided colonic diverticular bleeding. Hence, laparoscopic surgery can be feasible for right-sided colonic diverticular bleeding provided that the patient's general condition is stable.

Influence of Suture Materials on Incisional Hernia Rate after Laparoscopic Colorectal Cancer Surgery: A Propensity Score Analysis

Objectives

Incisional hernia is a common problem after colorectal surgery, and a laparoscopic approach does not reduce the incisional hernia rate. Previous reports have described the risk factors for incisional hernia; however, the impact of suture materials remains unclear. As such, this study compared the incisional hernia rate using different suture materials for abdominal wall closure after laparoscopic colorectal cancer surgery.

Methods

Patients undergoing laparoscopic colorectal cancer surgery between January 2014 and December 2016 were included in this study. We separated patients into the following two groups based on the suture materials used for abdominal wall closure: (1.) fast-absorbable group and (2.) non-absorbable group. The primary outcome was incisional hernia rate that was diagnosed using computed tomography. We compared outcomes between these two groups using propensity score matching.

Results

Before matching, 394 patients were included (168 in the fast-absorbable group and 226 in the non-absorbable group). After one-to-one matching, patients were stratified into the fast-absorbable group (n = 158) and the non-absorbable group (n = 158). The incisional hernia rate was higher in the fast-absorbable group than in the non-absorbable group (13.9% vs. 6.3%; P = 0.04). The median time to develop an incisional hernia was significantly shorter in the fast-absorbable group (6.7 months vs. 12.3 months; P < 0.01). The incidence of surgical site infection was not different between the two groups, but the incidence of suture sinus was lower in the fast-absorbable group (0% vs. 5.1%; P < 0.01).

Conclusions

The use of fast-absorbable sutures may increase the risk of incisional hernia after laparoscopic colorectal cancer surgery.

Outcome of radical surgery for gallbladder carcinoma according to TNM stage: implications for adjuvant therapeutic strategies

PURPOSE

Outcomes following surgery for advanced gallbladder carcinoma remain unsatisfactory. This study aimed to determine the surgical outcome and effectiveness of adjuvant chemotherapy according to TNM stage in patients with gallbladder carcinoma.

METHODS

A total of 200 patients undergoing surgery for gallbladder carcinoma were enrolled. Clinicopathological data were evaluated and surgical outcomes were compared between patients with and without adjuvant chemotherapy according to TNM stage.

RESULTS

The 5-year overall survival (OS) after resection for patients with stage I (n = 27), IIA (n = 18), IIB (n = 28), IIIA (n = 25), IIIB (n = 43), IVA (n = 7), and IVB (n = 52) disease was 90.8%, 94.4%, 73.6%, 33.7%, 57.7%, 14.3%, and 11.8%, respectively (p < 0.001). R0 resection was performed in all patients with stage I or II disease, in 89.7% of those with stage III disease, and 69.5% of those with stage IV disease. For patients with stage III disease, adjuvant chemotherapy was associated with improved OS (5-year OS, 60.9% vs. 41.1%; p = 0.028) and was an independent prognostic factor (hazard ratio, 2.045; p = 0.039). For patients with stage IV disease, adjuvant chemotherapy appeared to affect OS (5-year OS, 25.1% vs. 5.3%; p = 0.041); R0 resection (hazard ratio, 1.882; p = 0.040) was the only independent prognostic factor.

CONCLUSION

TNM stage clearly predicts survival after resection of gallbladder carcinoma. R0 resection with adjuvant chemotherapy is recommended for long-term survival in the multimodal management of patients with stage III or IV gallbladder carcinoma.

Inguinal Herniation After Living Donor Kidney Transplantation: A Case Report

A 68-year-old male patient received a living donor kidney transplantation 8 years earlier for end-stage kidney disease secondary to IgA nephropathy. His post-transplantation follow-up had been routinely performed with laboratory examinations, ultrasound, and computed tomography (CT). His kidney graft function had been excellent and stable, as shown by a baseline serum creatinine level of 1.0 mg/dL. At referral, regular follow-up ultrasound and CT showed allograft hydroureteronephrosis. He did not have any complaints, but his physical examination revealed right inguinal bulging that was 3.5 × 3.5 cm. Abdominal enhanced CT revealed transplant allograft hydroureteronephrosis due to ipsilateral herniation of ureteroneocystostomy into the right inguinal canal. His serum creatinine level was slightly elevated (1.1 mg/dL). Then, he underwent an open right inguinal hernia repair. Paraperitoneal allograft hydroureteronephrosis and bladder herniation was confirmed at surgery, and hernioplasty with polypropylene mesh reinforcement was successfully performed. The postoperative course was uneventful. He was discharged on the seventh day after surgery. Six weeks after surgery, CT revealed disappearance of allograft hydroureteronephrosis and no sign of inguinal hernia recurrence with the serum creatinine stable at 1.0 mg/dL. Transplant ureteral obstruction due to inguinal hernia is a rare complication after kidney transplantation. However, transplant ureter or bladder herniation should be considered in the differential diagnosis of graft hydroureteronephrosis for preventing allograft loss.

[A Case of Peritoneal Metastases after Radiofrequency Ablation for Liver Metastasis from a Pancreatic Neuroendocrine Tumor]

A 77-year-old woman presented with peritoneal metastases from a pancreatic neuroendocrine tumor(p-NET). At the age of 56 years, she underwent distal pancreatectomy for p-NET, which was pathologically diagnosed as G2. She underwent right hemihepatectomy for liver metastasis(S6)from the p-NET 10 years post-pancreatectomy. Eight years post-hepatectomy, radiofrequency ablation(RFA)was attempted for liver metastasis(S4)from the p-NET. However, RFA was not completed because of hematoma development along the needle tract of RFA. She underwent partial hepatectomy for this lesion 6 months post-RFA. Two years post-RFA, localized peritoneal metastases on the right diaphragm were detected. She underwent en bloc tumor resection with partial resection of the diaphragm. She remains alive and well with no evidence of disease 2 years post-resection of the peritoneal metastases from the p-NET.

Lymphatic spread of T2 gallbladder carcinoma: Regional lymphadenectomy is required independent of tumor location

BACKGROUND

This study aimed to investigate the incidence and distribution of regional lymph node metastasis according to tumor location, and to clarify whether tumor location could determine the extent of regional lymphadenectomy in patients with pathological T2 (pT2) gallbladder carcinoma.

METHODS

In total, 81 patients with pT2 gallbladder carcinoma (25 with pT2a tumors and 56 with pT2b tumors) who underwent radical resection were enrolled. Tumor location was determined histologically in each gallbladder specimen.

RESULTS

Survival after resection was significantly worse in patients with pT2b tumors than those with pT2a tumors (5-year survival, 72% vs. 96%; p = 0.027). Tumor location was an independent prognostic factor on multivariate analysis (hazard ratio, 14.162; p = 0.018). The incidence of regional lymph node metastasis was significantly higher in patients with pT2b tumors than in those with pT2a tumors (46% vs. 20%; p = 0.028). However, the number of positive nodes was similar between the two groups (median, 2 vs. 2; p = 0.910). For node-positive patients with pT2b tumors, metastasis was found in every regional node group (12%-63%), whereas even for node-positive patients with pT2a tumors, metastasis was observed in regional node groups outside the hepatoduodenal ligament.

CONCLUSIONS

Tumor location in patients with pT2 gallbladder carcinoma can predict the presence or absence of regional lymph node metastasis but not the number and anatomical distribution of positive regional lymph nodes. The extent of regional lymphadenectomy should not be changed even in patients with pT2a tumors, provided that they are fit enough for surgery.

[Surgical Resection after Transarterial Chemoembolization for Hepatocellular Carcinoma with Bile Duct Tumor Thrombus-Report of a Long-Term Survivor]

A 78-year-old woman with jaundice was referred to our hospital. On admission, serological testing for viral hepatitis was negative and serum levels of AFP and PIVKA-Ⅱ were elevated(925 ng/mL and 6,820 mAU/mL, respectively). Computed tomography revealed a main tumor measuring 3 cm in size at segment 1 of the liver and bile duct tumor thrombus extending to the right hepatic duct. A diagnosis of hepatocellular carcinoma with a bile duct tumor thrombus was made. After endoscopic biliary drainage for obstructive jaundice and transarterial chemoembolization for the lesions, she underwent left hepatectomy, resection of the caudate lobe, extrahepatic bile duct resection, and cholecystectomy. The hepatic side of the extrahepatic bile duct was transected at the confluence of the right anterior and posterior ducts because invasion of the tumor thrombus to the right hepatic duct was suspected on cholangioscopy. Histological examination revealed the tumor to be a moderately differentiated hepatocellular carcinoma with bile duct tumor thrombus. Surgical margins were negative, and vascular invasion was not found. She remains alive and well with no evidence of disease 64 months after hepatectomy.

[A Case of Peritoneal Recurrence of Invasive Ductal Carcinoma Derived from Intraductal Papillary Mucinous Neoplasm after Surgery Treated with Palliative Radiation Therapy and Chemotherapy]

An 82-year-old man with a diagnosis ofintraductal papillary mucinous carcinoma(IPMC)underwent pancreaticoduodenectomy followed by adjuvant chemotherapy with S-1. Six months after surgery, he had upper abdominal pain, and CT demonstrated a recurrent intraabdominal tumor located at the surgical incision scar. It was diagnosed as a solitary peritoneal recurrence, and palliative radiation therapy at a dose of 30 Gy was performed for the relief of abdominal pain after administration ofoxycodone. He was free ofpain without pharmacological therapy and received subsequent chemotherapy with nabpaclitaxel plus gemcitabine(GnP). He remains free ofpain and alive without progression ofthe disease 24 months after recurrence. Hypofractionated-accelerated radiotherapy is feasible and results in pain relief for local recurrence of IPMC.

[Pancreaticoduodenectomy for Recurrent Retroperitoneal Liposarcoma]

A 56-year-old woman was referred to our hospital with complaints of appetite loss and abdominal distension. Enhanced abdominal computed tomography revealed a giant retroperitoneal tumor. We performed en bloc tumor resection. The histological diagnosis was of a dedifferentiated liposarcoma. One year after the initial surgery, 2 tumors were detected around the pancreas using computed tomography. We made a diagnosis of recurrent retroperitoneal liposarcoma and attempted surgical removal of the tumors. However, 1 of the tumors firmly adhered to the pancreas and duodenum; thus, we performed subtotal stomach-preserving pancreaticoduodenectomy to remove the tumors. The histological diagnosis was the same as that obtained during the initial surgery: a dedifferentiated liposarcoma. The patient remains alive and well with no evidence of disease 2 years after the initial surgery.

[A Case of Long-Term Survival after Reoperation for Neck Lymph Node Metastasis Occurring Seven Years after Pancreaticoduodenectomy for Pancreatic Adenocarcinoma]

A 59-year-old woman with pancreatic cancer underwent pancreaticoduodenectomy. The tumor was histologically diagnosed as a well-differentiated tubular adenocarcinoma with a small amount of mucinous component. After resection, the patient underwent hepatic perfusion therapy using 5-FU and gemcitabine chemotherapy for 1 year. 7 years after the initial surgery, CT and PET-CT revealed an isolated enlarged lymph node in the left neck. As the patient had no other metastasis, lymphadenectomy was performed. A diagnosis of lymph node metastasis originating from pancreatic cancer was confirmed on the basis of histological and immunohistopathological assessments. After the second resection, chemotherapy with S-1 was administered for 1 year. The patient has been alive without tumor relapse for 11 years. In patients with late recurrence after pancreatectomy, aggressive isolated lymph node resection and maintained chemotherapy may contribute to the improvement in prognosis.

[Surgical Resection for Peritoneal Metastasis in Hepatocellular Carcinoma-A Report of Three Cases]

Peritoneal metastasis is relatively rare in patients with hepatocellular carcinoma(HCC). No consensus has been reached regarding the treatment of this type of metastasis. Herein, we report 3 patients who underwent resection of peritoneal metastasis due to HCC. Case 1: A 48-year-old man underwent hepatectomy twice and radiofrequency ablation(RFA)once for HCC. Eight years after the initial resection, he underwent resection of peritoneal metastasis in the pelvic floor. He is alive with disease 17 months after the last operation. Case 2: A 71-year-old man with a history of percutaneous ablation therapy for HCC 3 times underwent hepatectomy for recurrent HCC. During the laparotomy, a peritoneal metastatic tumor was found near the live tumor, and simultaneous resection of both the tumors was performed. The patient died of recurrent disease 20 months after the last resection. Case 3: A 58-year-old man underwent hepatectomy for HCC and RFA for its recurrence. Peritoneal metastasis that invaded the duodenum was detected 8 years after the hepatectomy. Although the metastatic tumor was resected, he died of the carcinoma 2 months after the resection. We concluded that resection of peritoneal metastasis provides a survival benefit for selected patients with HCC.

Surgical management of carcinoma in situ at ductal resection margins in patients with extrahepatic cholangiocarcinoma

Recent advances in dimensional imaging, surgical technique, and perioperative patient care have resulted in increased rates of complete resection with histopathologically negative margins and improved surgical outcomes in patients with extrahepatic cholangiocarcinoma. However, achieving cancer-free resection margins at ductal stumps in surgery for this disease remains challenging because of longitudinal extension, which is one of the hallmarks of extrahepatic cholangiocarcinoma. When the ductal resection margins are shown to be positive on examination of frozen sections, discrimination between carcinoma in situ and invasive carcinoma is clinically important because residual carcinoma in situ may lead to late local recurrence whereas residual invasive carcinoma is associated with early local recurrence. Residual invasive carcinoma at the ductal margins should be avoided whenever technically feasible. Residual "carcinoma in situ" at the ductal margins appears to be allowed in resection for the advanced disease because it has less effect on survival than other adverse prognostic factors (pN1 and/ or pM1). However, in surgery for early-stage (pTis-2N0M0) extrahepatic cholangiocarcinoma, residual carcinoma in situ at the ductal margins may have an adverse effect on long-term survival, so should be avoided whenever possible. In this review, we focus on the histopathological term "carcinoma in situ," the biological behavior of residual carcinoma in situ at ductal resection margins, intraoperative histological examination of the ductal resection margins, outcome of additional resection for positive ductal margins, and adjuvant therapy for patients with positive margins.

Hand-assisted laparoscopic Hassab's procedure for esophagogastric varices with portal hypertension

Background

Laparoscopic surgery for patients with portal hypertension is considered to be contraindicated because of the high risk of massive intraoperative hemorrhaging. However, recent reports have shown hand-assisted laparoscopic surgery for devascularization and splenectomy to be a safe and effective method of treating esophagogastric varices with portal hypertension. The aim of this study is to evaluate the efficacy of hand-assisted laparoscopic devascularization and splenectomy (HALS Hassab’s procedure) for the treatment of esophagogastric varices with portal hypertension.

Case presentation

From 2009 to 2016, seven patients with esophagogastric varices with portal hypertension were treated with hand-assisted laparoscopic devascularization and splenectomy in our institute. Four men and three women with a median age of 61 years (range 35–71) were enrolled in this series. We retrospectively reviewed the medical records for the perioperative variables, postoperative mortality and morbidity, and postoperative outcomes of esophagogastric varices. The median operative time was 455 (range 310–671) min. The median intraoperative blood loss was 695 (range 15–2395) ml. The median weight of removed spleen was 507 (range 242–1835) g. The conversion rate to open surgery was 0%. The median postoperative hospital stay was 21 (range 13–81) days. During a median 21 (range 3–43) months of follow-up, the mortality rate was 0%. Four postoperative complications (massive ascites, enteritis, intra-abdominal abscess, and intestinal ulcer) were observed in two patients. Those complications were treated successfully without re-operation. Esophagogastric varices in all patients disappeared or improved. Bleeding from esophagogastric varices was not observed during the follow-up period.

Conclusion

Although our data are preliminary, hand-assisted laparoscopic devascularization and splenectomy proved an effective procedure for treating esophagogastric varices in patients with portal hypertension.

Gastric adenosquamous carcinoma producing granulocyte-colony stimulating factor: a case of a rare malignancy

Background

A gastric adenosquamous carcinoma (ASC) that produces granulocyte-colony stimulating factor (G-CSF) is an uncommon malignancy with a poor prognosis. Due to the rarity of this lesion, a standard treatment for the disease has not been established.

Case presentation

We describe a case of a 66-year-old male with a G-CSF-producing gastric ASC who presented with severe anemia and leukocytosis. A radical resection was performed, followed by a course of adjuvant chemotherapy. Histopathologic examination revealed that the tumor consisted of areas of both squamous cell carcinoma and adenocarcinoma. Immunohistochemical staining with an anti-G-CSF antibody was also positive. He was started on adjuvant capecitabine and oxaliplatin (CapeOX) 6 weeks after surgery. The patient stopped treatment after 3 months due to his own preference. Eight months following surgery, the patient was found to have diffuse lymph node, liver, and peritoneal metastases.

Conclusions

G-CSF-producing gastric ASC is a rare and aggressive tumor. Because patients are usually diagnosed at an advanced stage, multidisciplinary evaluation and innovative treatments are needed. The rarity of this disease, with its aggressive features, poses a significant challenge in its treatment. In this brief case report, we summarize the management and outcomes of G-CSF-producing gastric ASC.

[Resection for a Locally Advanced Duodenal Adenocarcinoma with Obstructive Jaundice and Hepatic and Pancreatic Invasion - A Case Report]

A 64-year-old woman diagnosed with duodenal adenocarcinoma with duodenal stenosis and obstructive jaundice was referred to our hospital. Computed tomography revealed a tumor measuring 9×6 cm in the second portion of the duodenum that had invaded the liver(S6)and head of the pancreas. After percutaneous transhepatic biliary drainage for obstructive jaundice, the patient underwent subtotal stomach-preserving pancreaticoduodenectomy, partial resection of the liver(S6), and partial resection of the colon. Histologic examination showed the primary tumor to be moderately and poorly differentiated adenocarcinoma with hepatic and pancreatic invasion; lymph node metastasis was not found. The patient received S-1 for 1 year and remains alive and well with no evidence of disease 15 months after resection.

[Long-Term Survival after Reoperation for Lung Metastasis of Resected Pancreatic Adenocarcinoma - A Case Report]

A 66-year-old woman with pancreatic cancer underwent resection of the pancreatic body and tail. Thirty-seven months after the initial surgery, a tumor was found in S4 of the right lung, for which resection of the middle lobe of the lung was performed. A diagnosis of lung metastasis originating from pancreatic cancer was confirmed based on histological and immunohistopathological assessments. Sixty-seven months after the initial surgery, despite the gemcitabine-based adjuvant chemotherapy, a tumor was detected in S3 of the left lung, for which partial lung resection was performed. Similar to the previous diagnosis, the tumor was diagnosed as lung metastasis of pancreatic cancer on the basis of the pathological findings. After the third operation, despite gemcitabine and S-1 chemotherapy, widespread pulmonary metastasis developed. One hundred and thirty months after the initial surgery, the patient died of respiratory failure due to carcinomatous pleurisy.

[Surgical Resection for Carcinoma Arising from the Remnant Intrapancreatic Bile Duct after Excision of a Congenital Choledochal Cyst - A Case Report]

A 77-year-old woman presented with a high fever. She had a history of resection of the extrahepatic bile duct, cholecystectomy, and hepaticojejunostomy for a congenital choledochal cyst, 23 years previously. Computed tomography showed a tumor measuring 90mm behind the head of the pancreas. This tumor appeared to invade the duodenum and pancreas, although swollen lymph nodes and distant metastasis were not detected. The patient was diagnosed with a carcinoma arising from the intrapancreatic remnant bile duct. A subtotal stomach-preserving pancreaticoduodenectomy and regional lymphadenectomy were performed. The patient remains alive and well with no evidence of disease 11 months after resection.

[Lymph Node Recurrence of Small Cell Carcinoma of the Extrahepatic Bile Ducts Effectively Treated with Cisplatin plus Irinotecan Chemotherapy - Report of a Case]

A 78-year-old man with jaundice was diagnosed with perihilar cholangiocarcinoma(Bismuth type I ). After endoscopic biliary drainage for jaundice, a subtotal stomach-preserving pancreaticoduodenectomy was performed. Histologic examination and immunohistochemical staining with chromogranin A, synaptophysin, and CD56 resulted in a diagnosis of small cell carcinoma. Of the 18 dissected lymph nodes, 8 nodes contained a metastatic tumor. Left supraclavicular and paraaortic lymph node metastases were detected by computed tomography 5 months after the resection. He received cisplatin plus irinotecan chemotherapy, and after 2 courses of the chemotherapy, both metastatic lesions were reduced in size. He remains alive and well with no evidence of progressive disease after 6 courses of chemotherapy.

Bile duct stone formation around a nylon suture after gastrectomy: a case report

BACKGROUND

Many cases of choledocholiths formed around sutures and clips used during cholecystectomy have been reported. We describe a case of gallstone formation around a nylon suture after non-biliary surgery. To the best of our knowledge, this is the first report of such a case.

CASE PRESENTATION

A 75-year-old Japanese man, who had undergone distal gastrectomy for gastric cancer and reconstruction with the Billroth II method 8 years earlier, presented with gastric discomfort. Abdominal ultrasonography was conducted and we diagnosed cholecysto-choledocholithiasis with dilatation of the intrahepatic bile duct. He underwent cholecystectomy and cholangioduodenostomy for choledocholith removal. Gallstones, which had formed around a nylon suture used during the previous gastrectomy, were found in the bile duct. Sutures of the same material had also been placed on the duodenum. Chemical analysis revealed that the stones were composed of calcium bilirubinate. The patient was discharged on postoperative day 19, and choledocholithiasis has not recurred thus far.

CONCLUSION

The findings from this case suggest that standard, non-resorbable sutures used in gastrectomy may be associated with the formation of bile duct stones; therefore, absorbable suture material may be required to avert gallstone formation even in the case of gastrectomy.

Real-time detection of hepatic micrometastases from pancreatic cancer by intraoperative fluorescence imaging: preliminary results of a prospective study

BACKGROUND

Recently, a highly sensitive fluorescent imaging technique was developed for the real-time identification of hepatic tumors. The authors applied this procedure for the intraoperative detection of radiographically occult hepatic micrometastases from pancreatic cancer.

METHODS

Forty-nine consecutive patients with pancreatic cancer who underwent surgical intervention were examined. Preoperative clinical images had not revealed any hepatic metastases. On the day before surgery, indocyanine green was injected intravenously. During the operation, the liver was observed with a near-infrared camera system, and abnormal fluorescent foci were examined by frozen-section histology. The patients with hepatic micrometastases were judged to have unresectable disease and underwent only palliative surgery followed by systemic chemotherapy using gemcitabine.

RESULTS

Abnormal hepatic fluorescence at least 1.5 mm in greatest dimension without any apparent tumor was observed in 13 patients. Among them, histologic examination confirmed micrometastases in 8 of 49 patients (16%). All patients with hepatic micrometastases had clinical T3 or T4 disease and high serum CA19-9 levels (P = .042). On follow-up computed tomography images that were obtained within 6 months after surgery, the patients with hepatic micrometastases manifested hepatic overt metastases (7 of 8 patients; 88%) more frequently than the patients without hepatic micrometastases (4 of 41 patients; 10%; P < .001). Regardless of histologic confirmation, the positive predictive value of abnormal fluorescence for the manifestation of hepatic relapse within 6 months was 77% (10 of 13 patients), and the negative predictive value was 97% (35 of 36 patients).

CONCLUSIONS

Indocyanine green-fluorescent imaging can detect hepatic micrometastases of pancreatic cancer during surgery. The hepatic micrometastases seem to have an adverse clinical impact identical to that of evident distant metastases.

Identification of candidate genes involved in the radiosensitivity of esophageal cancer cells by microarray analysis

Radiotherapy plays a key role in the control of tumor growth in esophageal cancer patients. To identify the patients who will benefit most from radiation therapy, it is important to know the genes that are involved in the radiosensitivity of esophageal cancer cells. Hence, we examined the global gene expression in radiosensitive and radioresistant esophageal squamous cell carcinoma cell lines. Radiosensitivities of 13 esophageal cancer cell lines were measured. RNA was extracted from each esophageal cancer cell line and a normal esophageal epithelial cell line, and the global gene expression profiles were analyzed using a 34 594-spot oligonucleotide microarray. In the clonogenic assay, one cell line (TE-11) was identified to be highly sensitive to radiation, while the other cell lines were found to be relatively radioresistant. We identified 71 candidate genes that were differentially expressed in TE-11 by microarray analysis. The up-regulated genes included CABPR, FABP5, DSC2, GPX2, NME, CBR3, DOCK8, and ABCC5, while the down-regulated genes included RPA1, LDOC1, NDN, and SKP1A. Our investigation provided comprehensive information on genes related to radiosensitivity of esophageal cancer cells; this information can serve as a basis for further functional studies.

Gene expression profiling of the response of esophageal carcinoma cells to cisplatin

Cisplatin is the most common chemotherapeutic agent used in esophageal cancer. However, sensitivity to cisplatin varies greatly between patients. It is important to identify the gene(s) that are related to the sensitivity to cisplatin in esophageal cancer patients. The IC50 for cisplatin was measured for 15 esophageal cancer cell lines (TE1-5, TE8-15, KYSE140, and KYSE150). RNA was extracted from each of these cell lines and a normal esophageal epithelial cell line, namely, Het1A, and gene expression profiles were analyzed using an oligonucleotide microarray consisting of 34 594 genes. TE4 was highly resistant and TE12, 14, and 15 were sensitive to cisplatin. Thirty-seven genes were differentially expressed in the cisplatin-resistant esophageal cancer cell line. Our investigation provides a list of candidate genes that may be associated with resistance to cisplatin in esophageal cancer cells, which may serve as a basis for additional functional studies.

Relationship between expression of 5-fluorouracil metabolic enzymes and 5-fluorouracil sensitivity in esophageal carcinoma cell lines

5-Fluorouracil (5-FU) is a key drug in the treatment of esophageal squamous cell carcinoma (ESCC). Gene expression of 5-FU metabolic enzymes such as thymidylate synthase (TS), thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD) and orotate phosphoribosyl transferase (OPRT), has recently been investigated in order to predict the 5-FU sensitivity of several cancers. We examined the relationship between such gene expression and 5-FU sensitivity in 25 ESCC cell lines. TS, DPD, TP and OPRT mRNA levels were assessed by real-time polymerase chain reaction. The 50% inhibitory concentrations (IC50) of 5-FU in 25 ESCC cell lines were determined by cell proliferation assay. IC50 values for 5-FU ranged from 1.00 to 39.81 micromol/L. There were significant positive correlations between IC50 and TS mRNA expression (R(2) = 0.5781, P < 0.0001) and DPD mRNA expression (R(2) = 0.3573, P = 0.0016). There were no correlations between IC50 and TP or OPRT mRNA expression. TS and DPD mRNA expression levels may be useful indicators in predicting the anti-tumor activity of 5-FU in ESCC.

Antagonistic control of cell fates by JNK and p38-MAPK signaling

During the development and organogenesis of all multicellular organisms, cell fate decisions determine whether cells undergo proliferation, differentiation, or aging. Two independent stress kinase signaling pathways, p38-MAPK, and JNKs, have evolved that relay developmental and environmental cues to determine cell responses. Although multiple stimuli can activate these two stress kinase pathways, the functional interactions and molecular cross-talks between these common second signaling cascades are poorly elucidated. Here we report that JNK and p38-MAPK pathways antagonistically control cellular senescence, oncogenic transformation, and proliferation in primary mouse embryonic fibroblasts (MEFs). Similarly, genetic inactivation of the JNK pathway results in impaired proliferation of fetal hepatoblasts in vitro and defective adult liver regeneration in vivo, which is rescued by inhibition of the p38-MAPK pathway. Thus, the balance between the two stress-signaling pathways, MKK7-JNK and MKK3/6-p38-MAPK, determines cell fate and links environmental and developmental stress to cell cycle arrest, senescence, oncogenic transformation, and adult tissue regeneration.

Activation mechanism and physiological roles of stress-activated protein kinase/c-Jun NH2-terminal kinase in mammalian cells

Stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK), which belongs to the family of mitogen-activated protein kinase (MAPK), is activated by many types of cellular stress or extracellular signals. Recent studies, including the analysis with knockout cells and mice, have led towards understanding the molecular mechanism of stress-induced SAPK/JNK activation and the physiological roles of SAPK/JNK in embryonic development and immune responses. Two SAPK/JNK activators, SEK1 and MKK7, are required for full activation of SAPK/JNK, which responds to various stimuli in an all-or-none manner in mouse embryonic stem (ES) cells. SAPK/JNK activation plays essential roles in organogenesis during mouse development by regulating cell proliferation, survival or apoptosis and in immune responses by regulating cytokine gene expression. Furthermore, SAPK/JNK is involved in regulation of mRNA stabilization, cell migration, and cytoskeletal integrity. Thus, SAPK/JNK has a wide range of functions in mammalian cells.

Association of FcgammaRII with low-density detergent-resistant membranes is important for cross-linking-dependent initiation of the tyrosine phosphorylation pathway and superoxide generation

IgG immune complexes trigger humoral immune responses by cross-linking of FcRs for IgG (FcgammaRs). In the present study, we investigated role of lipid rafts, glycolipid- and cholesterol-rich membrane microdomains, in the FcgammaR-mediated responses. In retinoic acid-differentiated HL-60 cells, cross-linking of FcgammaRs resulted in a marked increase in the tyrosine phosphorylation of FcgammaRIIa, p58(lyn), and p120(c-cbl), which was inhibited by a specific inhibitor of Src family protein tyrosine kinases. After cross-linking, FcgammaRs and tyrosine-phosphorylated proteins including p120(c-cbl) were found in the low-density detergent-resistant membrane (DRM) fractions isolated by sucrose-density gradient ultracentrifugation. The association of FcgammaRs as well as p120(c-cbl) with DRMs did not depend on the tyrosine phosphorylation. When endogenous cholesterol was reduced with methyl-beta-cyclodextrin, the cross-linking did not induce the association of FcgammaRs as well as p120(c-cbl) with DRMs. In addition, although the physical association between FcgammaRIIa and p58(lyn) was not impaired, the cross-linking did not induce the tyrosine phosphorylation. In human neutrophils, superoxide generation induced by opsonized zymosan or chemoattractant fMLP was not affected or increased, respectively, after the methyl-beta-cyclodextrin treatment, but the superoxide generation induced by the insoluble immune complex via FcgammaRII was markedly reduced. Accordingly, we conclude that the cross-linking-dependent association of FcgammaRII to lipid rafts is important for the activation of FcgammaRII-associated Src family protein tyrosine kinases to initiate the tyrosine phosphorylation cascade leading to superoxide generation.

Increase of cGMP, cADP-ribose and inositol 1,4,5-trisphosphate preceding Ca2+ transients in fertilization of sea urchin eggs

Transient increases, or oscillations, of cytoplasmic free Ca2+ concentration, [Ca2+]i, occur during fertilization of animal egg cells. In sea urchin eggs, the increased Ca2+ is derived from intracellular stores, but the principal signaling and release system involved has not yet been agreed upon. Possible candidates are the inositol 1,4,5-trisphosphate receptor/channel (IP3R) and the ryanodine receptor/channel (RyR) which is activated by cGMP or cyclic ADP-ribose (cADPR). Thus, it seemed that direct measurements of the likely second messenger candidates during sea urchin fertilization would be essential to an understanding of the Ca2+ signaling pathway. We therefore measured the cGMP, cADPR and inositol 1,4,5-trisphosphate (IP3) contents of sea urchin eggs during the early stages of fertilization and compared these with the [Ca2+]i rise in the presence or absence of an inhibitor against soluble guanylate cyclase. We obtained three major experimental results: (1) cytosolic cGMP levels began to rise first, followed by cADPR and IP3 levels, all almost doubling before the explosive increase of [Ca2+]i; (2) most of the rise in IP3 occurred after the Ca2+ peak; IP3 production could also be induced by the artificial elevation of [Ca2+]i, suggesting the large increase in IP3 is a consequence, rather than a cause, of the Ca2+ transient; (3) the measured increase in cGMP was produced by the soluble guanylate cyclase of eggs, and inhibition of soluble guanylate cyclase of eggs diminished the production of both cADPR and IP3 and the [Ca2+]i increase without the delay of Ca2+ transients. Taken together, these results suggest that the RyR pathway involving cGMP and cADPR is not solely responsible for the initiating event, but contributes to the Ca2+ transients by stimulating IP3 production during fertilization of sea urchin eggs.

Ski7p G protein interacts with the exosome and the Ski complex for 3'-to-5' mRNA decay in yeast

Two cytoplasmic mRNA-decay pathways have been characterized in yeast, and both are initiated by shortening of the 3'-poly(A) tail. In the major 5'-to-3' decay pathway, the deadenylation triggers removal of the 5'-cap, exposing the transcript body for 5'-to-3' degradation. An alternative 3'-to-5' decay pathway also follows the deadenylation and requires two multi-complexes: the exosome containing various 3'-exonucleases and the Ski complex consisting of the RNA helicase Ski2p, Ski3p and Ski8p. In addition, Ski7p, which has an N-terminal domain and a C-terminal elongation factor 1alpha-like GTP-binding domain, is involved in the 3'-to-5' decay. However, physical interaction between the exosome and the Ski complex, together with the function of Ski7p, has remained unknown. Here we report that the N domain of Ski7p is required and sufficient for the 3'-to-5' decay. Furthermore, the exosome and the Ski complex interact with the different regions of Ski7p N domain, and both interactions are required for the 3'-to-5' decay. Thus, Ski7p G protein appears to function as a signal-coupling factor between the two multi-complexes operating in the 3'-to-5' mRNA-decay pathway.

Impaired synergistic activation of stress-activated protein kinase SAPK/JNK in mouse embryonic stem cells lacking SEK1/MKK4: different contribution of SEK2/MKK7 isoforms to the synergistic activation

Stress-activated protein kinase/c-Jun NH(2)-terminal kinase (SAPK/JNK), which is a member of the mitogen-activated protein kinase (MAPK) family, plays an important role in a stress-induced signaling cascade. SAPK/JNK activation requires the phosphorylation of Thr and Tyr residues in its Thr-Pro-Tyr motif, and SEK1 (MKK4) and MKK7 (SEK2) have been identified as the upstream MAPK kinases. Here we examined the activation and phosphorylation sites of SAPK/JNK and differentiated the contribution of SEK1 and MKK7alpha1, -gamma1, and -gamma2 isoforms to the MAPK activation. In SEK1-deficient mouse embryonic stem cells, stress-induced SAPK/JNK activation was markedly impaired, and this defect was accompanied with a decreased level of the Tyr phosphorylation. Analysis in HeLa cells co-transfected with the two MAPK kinases revealed that the Thr and Tyr of SAPK/JNK were independently phosphorylated in response to heat shock by MKK7gamma1 and SEK1, respectively. However, MKK7alpha1 failed to phosphorylate the Thr of SAPK/JNK unless its Tyr residue was phosphorylated by SEK1. In contrast, MKK7gamma2 had the ability to phosphorylate both Thr and Tyr residues. In all cases, the dual phosphorylation of the Thr and Tyr residues was essentially required for the full activation of SAPK/JNK. These data provide the first evidence that synergistic activation of SAPK/JNK requires both phosphorylation at the Thr and Tyr residues in living cells and that the preference for the Thr and Tyr phosphorylation was different among the members of MAPK kinases.

Association of phosphatidylinositol 3-kinase composed of p110beta-catalytic and p85-regulatory subunits with the small GTPase Rab5

A family of phosphatidylinositol 3-kinases (PI 3-kinase), comprising three major classes (I-III) in terms of substrate specificity and regulation, play important roles in a variety of cell functions. We previously reported that the class-I heterodimeric PI 3-kinase consisting of p110beta-catalytic and p85-regulatory subunits is synergistically activated by two different types of membrane receptors, one possessing tyrosine kinase activity and the other activating trimeric G proteins. Here we report an additional unique feature of the p110beta/p85 PI 3-kinase. The small GTPase Rab5 was identified as a binding protein for the p110beta-catalytic subunit in a yeast two-hybrid screening system. The interaction appears to require at least two separated amino-acid sequences present specifically in the beta isoform of p110 and the GTP-bound form of Rab5. The expressions of constitutively active and dominant negative mutants of Rab5 in THP-1 cells induce the stimulation and inhibition, respectively, of protein kinase B activity, which is dependent on the PI 3-kinase product phosphatidylinositol 3,4,5-triphosphate. These results suggest that there is a specific interaction between GTP-bound Rab5 and the p110beta/p85 PI 3-kinase, leading to efficient coupling of the lipid kinase product to its downstream target, protein kinase B.

Complex gangliosides as cell surface inhibitors for the ecto-NAD+ glycohydrolase of CD38

Leukocyte cell surface antigen CD38 is a single-transmembrane protein whose extracellular domain has catalytic activity for NAD(+) glycohydrolase (NADase). We previously reported that b-series gangliosides inhibit the NADase activity of the extracellular domain of CD38 expressed as a fusion protein [Hara-Yokoyama, M., Kukimoto, I., Nishina, H., Kontani, K., Hirabayashi, Y., Irie, F., Sugiya, H., Furuyama, S., and Katada, T. (1996) J. Biol. Chem. 271, 12951-12955]. In the present study, we examined the effect of exogenous gangliosides on the NADase activity of CD38 on the surface of retinoic acid-treated human leukemic HL60 cells and CD38-transfected THP-1 cells. After incubation of the cells with G(T1b), inhibition of NADase activity was observed. The time course of inhibition was slower than that of the incorporation of G(T1b) into the cells, suggesting that incorporation into the cell membranes is a prerequisite for inhibition. Inhibition occurred efficiently when G(T1b) and CD38 were present on the same cells (cis interaction) rather than on different cells (trans interaction). Although gangliosides may affect localization of cell surface proteins, indirect immunofluorescence intensity due to CD38 was not affected after G(T1b) treatment. Comparison of the effect of G(T1b) and G(D1a) indicates that the tandem sialic acid residues linked to the internal galactose residue of the gangliotetraose core are crucial to the inhibition. These results suggest a novel role of complex gangliosides for the first time as cell surface inhibitors of CD38 through specific and cis interaction between the oligosaccharide moiety and the extracellular domain.

Possible association of BLM in decreasing DNA double strand breaks during DNA replication

Bloom's syndrome (BS) is a rare genetic disorder and the cells from BS patients show genomic instability and an increased level of sister chromatid exchange (SCE). We generated BLM(-/-) and BLM(-/-)/RAD54(-/-) DT40 cells from the chicken B-lymphocyte line DT40. The BLM(-/-) DT40 cells showed higher sensitivity to methyl methanesulfonate and elevated levels of SCE as expected. The targeted integration frequency was also increased remarkably in BLM(-/-) cells. The SCE frequency increase in BLM(-/-) cells was considerably reduced and the enhanced targeted integration observed in BLM(-/-) cells was almost completely abolished in BLM(-/-)/RAD54(-/-) cells, indicating that a large portion of the SCE in BLM(-/-) cells occurs via homologous recombination, and homologous recombination events increase with the defect of BLM function. The BLM(-/-)/RAD54(-/-) cells showed a slow growth phenotype and an increased incidence of chromosome-type breaks/gaps while each single mutant showed relatively small numbers of chromosome-type breaks/gaps.

Expression and characterization of Xenopus type I collagen alpha 1 (COL1A1) during embryonic development

A cDNA encoding Xenopus type I collagen alpha 1 (Xenopus COL1A1) has been isolated from an ovary cDNA library. The COL1A1 cDNA is approximately 5.7 kb pairs and encodes 1447 amino acids. The putative COL1A1 polypeptide shares high identities of amino acid sequence with other vertebrate COL1A1 proteins. The level of Xenopus COL1A1 transcripts was increased markedly in the posterior region of the embryo at the tail-bud stage, then gradually spread to the anterior region. Histological observations of the tail-bud embryos showed that COL1A1 was mainly expressed in the inner layer of the posterior dorsal epidermis exposed to the somite mesoderm, except for in the dorsal fin. Less intense signals were also detected in the outer layer of the dorsal epidermis and dermatome. The expression of COL1A1 was increased in posteriorized embryos resulting from treatment with retinoic acid but decreased in hyper-dorsalized embryos resulting from lithium chloride treatment. These results suggest that COL1A1 is a major component of the dorsal dermis exposed to the somite in Xenopus embryos, but its expression is not related to the temporal sequence of somite segregation.

Crystallization and preliminary X-ray diffraction analysis of the extracellular domain of the cell surface antigen CD38 complexed with ganglioside

The cell surface antigen CD38 is a multifunctional ectoenzyme that acts as an NAD(+) glycohydrolase, an ADP-ribosyl cyclase, and also a cyclic ADP-ribose hydrolase. The extracellular catalytic domain of CD38 was expressed as a fusion protein with maltose-binding protein, and was crystallized in the complex with a ganglioside, G(T1b), one of the possible physiological inhibitors of this ectoenzyme. Two different crystal forms were obtained using the hanging-drop vapor diffusion method with PEG 10,000 as the precipitant. One form diffracted up to 2.4 A resolution with synchrotron radiation at 100 K, but suffered serious X-ray damage. It belongs to the space group P2(1)2(1)2(1) with unit-cell parameters of a = 47.9, b = 94.9, c = 125.2 A. The other form is a thin plate, but the data sets were successfully collected up to 2.4 A resolution by use of synchrotron radiation at 100 K. The crystals belong to the space group P2(1) with unit-cell parameters of a = 57.4, b = 51.2, c = 101.1 A, and beta = 97.9 degrees, and contain one molecule per asymmetric unit with a VM value of 2.05 A(3)/Da.

Novel function of the eukaryotic polypeptide-chain releasing factor 3 (eRF3/GSPT) in the mRNA degradation pathway

The mammalian GTP-binding protein GSPT, whose carboxy-terminal sequence is homologous to the eukaryotic elongation factor EF1alpha, binds to the polypeptide chain releasing factor eRF1 to function as eRF3 in translation termination. However, the amino-terminal domain of GSPT, which contains a prion-like sequence, is not required for the binding. Instead, the amino-terminal domain is capable of binding to the carboxy-terminal domain of polyadenylate-binding protein (PABP), whose amino terminus is associating with the poly(A) tail of mRNAs, presumably for their stabilization. Interestingly, multimerization of PABP with poly(A), which is ascribed to the action of its carboxy-terminal domain, was completely inhibited by the interaction with the amino-terminal domain of GSPT. This may facilitate shortening of the poly(A) tail of mRNAs by an RNase. Thus, GSPT/eRF3 appears to function not only as a stimulator of eRF1 in the translation termination but also as an initiator of the mRNA degradation machinery. Further physiological and cell biological approaches will be necessary to show whether our current in vitro findings on GSPT/eRF3 indeed reflect its bifunctional properties in living cells.

Inhibition of phosphodiesterase/pyrophosphatase activity of PC-1 by its association with glycosaminoglycans

PC-1 is a type II membrane-bound glycoprotein consisting of a short N-terminal cytoplasmic domain and a large C-terminal extracellular domain, which contains phosphodiesterase/pyrophosphatase activity. When Jurkat T cells were cultured with dibutyryl cAMP, the membrane-bound PC-1 and its soluble form were induced. They were purified as a homodimer of a 130 kDa peptide and a 120 kDa monomer, respectively, and the same two forms could also be obtained from COS-7 cells that had been transfected with PC-1 cDNA. The membrane-bound and soluble forms of PC-1 were indistinguishable from each other in terms of their enzyme kinetics and N-glycosylated moieties. Thus, the enzymatically active and fully glycosylated form of soluble PC-1 was utilized to search for its interacting molecules. The phosphodiesterase/pyrophosphatase activity of PC-1 was competitively inhibited by glycosaminoglycans, such as heparin and heparan sulfate, which are the major components of the extracellular matrix. PC-1 was capable of binding to heparin-Sepharose and the binding was inhibited in the presence of the enzyme substrate, ATP or its nonhydrolyzable analog. The enzyme activity of PC-1 itself, however, was not required for the binding to heparin-Sepharose. These results suggest that PC-1 might function as an adhesion molecule independent of its enzyme activity to associate with glycosaminoglycans in the extracellular matrix.

Enhancement by adenosine of insulin-induced activation of phosphoinositide 3-kinase and protein kinase B in rat adipocytes

The role of adenosine receptor in regulation of insulin-induced activation of phosphoinositide 3-kinase (PI 3-kinase) and protein kinase B was studied in isolated rat adipocytes. Rat adipocytes are known to spontaneously release adenosine, which in turn binds and stimulates the adenosine A1 receptors on the cells. In the present study, we observed that degradation of this adenosine by adenosine deaminase attenuated markedly the insulin-induced accumulation of phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3), a product of PI 3-kinase. p-Aminophenylacetyl xanthine amine congener (PAPA-XAC), an inhibitor of the adenosine A1 receptor, also inhibited the insulin-induced PtdIns(3,4,5)P3 accumulation. When extracellular adenosine was inactivated by adenosine deaminase, phenylisopropyladenosine, an adenosine A1 receptor agonist, potentiated the insulin-induced accumulation of PtdIns(3,4,5)P3. Insulin-induced activation of protein kinase B, the activity of which is controlled by the lipid products of PI 3-kinase, was also potentiated by adenosine. Prostaglandin E2, another activator of a pertussis toxin-sensitive GTP-binding protein in these cells, potentiated the insulin actions. Thus, the receptors coupling to the GTP-binding protein were found to positively regulate the production of PtdIns(3,4,5)P3, a putative second messenger for insulin actions, in physiological target cells of insulin.

The eukaryotic polypeptide chain releasing factor (eRF3/GSPT) carrying the translation termination signal to the 3'-Poly(A) tail of mRNA. Direct association of erf3/GSPT with polyadenylate-binding protein

The mammalian GTP-binding protein GSPT, whose carboxyl-terminal sequence is homologous to the eukaryotic elongation factor EF1alpha, binds to the polypeptide chain releasing factor eRF1 to function as eRF3 in the translation termination. The amino-terminal domain of GSPT was, however, not required for the binding. Search for other GSPT-binding proteins in yeast two-hybrid screening system resulted in the identification of a cDNA encoding polyadenylate-binding protein (PABP), whose amino terminus is associating with the poly(A) tail of mRNAs presumably for their stabilization. The interaction appeared to be mediated through the carboxyl-terminal domain of PABP and the amino-terminal region of GSPT. Interestingly, multimerization of PABP with poly(A), which is ascribed to the action of its carboxyl-terminal domain, was completely inhibited by the interaction with the amino-terminal domain of GSPT. These results indicate that GSPT/eRF3 may play important roles not only in the termination of protein synthesis but also in the regulation of mRNA stability. Thus, the present study is the first report showing that GSPT/eRF3 carries the translation termination signal to 3'-poly(A) tail ubiquitously present in eukaryotic mRNAs.

G-protein betagamma subunit-dependent phosphorylation of 62-kDa protein in the early signaling pathway of starfish oocyte maturation induced by 1-methyladenine

In starfish oocytes, maturation is induced by a hormone, 1-methyladenine (1-MA), that binds to the receptors exposed to the outer surface of the plasma membrane. The signal of 1-MA stimulates the heterotrimeric G protein, resulting in dissociation of the betagamma subunit of G protein (Gbetagamma) from a pertussis toxin-sensitive Gi-type alpha subunit. To investigate the targets for Gbetagamma, we analyzed 1-MA- or Gbetagamma-dependent phosphorylation using in vivo and in vitro systems. A 62-kDa protein was phosphorylated immediately after 1-MA treatment in intact oocytes. In the cell-free preparations, the 62-kDa protein was also phosphorylated on serine residue(s) immediately after addition of 1-MA or Gbetagamma. The Gbetagamma-dependent phosphorylation of the 62-kDa protein was inhibited by wortmannin or LY294002, which are mechanistically different inhibitors of phosphatidylinositol 3-kinase (PI3K). LY294002 also inhibited Gbetagamma- as well as 1-MA-induced maturation of oocytes. Taken together, these results indicate that the 62-kDa protein functions downstream of Gbetagamma and PI3K in the early signaling pathway of 1-MA-induced starfish oocyte maturation. The phosphorylation of the 62-kDa protein may be required for the activation of maturation-promoting factor.

Synergistic activation of a family of phosphoinositide 3-kinase via G-protein coupled and tyrosine kinase-related receptors

Phosphoinositide 3-kinase (PI 3-kinase) is a key signaling enzyme implicated in a variety of receptor-stimulated cell responses. Stimulation of receptors possessing (or coupling to) protein-tyrosine kinase activates heterodimeric PI 3-kinases, which consist of an 85-kDa regulatory subunit (p85) containing Src-homology 2 (SH2) domains and a 110-kDa catalytic subunit (p110 alpha or p110 beta). Thus, this form of PI 3-kinases could be activated in vitro by a phosphotyrosyl peptide containing a YMXM motif that binds to the SH2 domains of p85. Receptors coupling to alpha beta gamma-trimeric G proteins also stimulate the lipid kinase activity of a novel p110 gamma isoform, which is not associated with p85, and thereby is not activated by tyrosine kinase receptors. The activation of p110 gamma PI 3-kinase appears to be mediated through the beta gamma subunits of the G protein (G beta gamma). In addition, rat liver heterodimeric PI 3-kinases containing the p110 beta catalytic subunit are synergistically activated by the phosphotyrosyl peptide plus G beta gamma. Such enzymatic properties were also observed with a recombinant p110 beta/p85 alpha expressed in COS-7 cells. In contrast, another heterodimeric PI 3-kinase consisting of p110 alpha and p85 in the same rat liver, together with a recombinant p110 alpha/p85 alpha, was not activated by G beta gamma, though their activities were stimulated by the phosphotyrosyl peptide. Synergistic activation of PI 3-kinase by the stimulation of the two major receptor types was indeed observed in intact cells, such as chemotactic peptide (N-formyl-Met-Leu-Phe) plus insulin (or Fc gamma II) receptors in differentiated THP-1 and CHO cells and adenosine (A1) plus insulin receptors in rat adipocytes. Thus, PI 3-kinase isoforms consisting of p110 beta catalytic and SH2-containing (p85 or its related) regulatory subunits appeared to function as a 'cross-talk' enzyme between the two signal transduction pathways mediated through tyrosine kinase and G protein-coupled receptors.