Mitsuyoshi Okazaki

The Angiotensin II type 1 receptor blocker candesartan suppresses proliferation and fibrosis in gastric cancer

Gastric cancer with peritoneal dissemination has poor clinical prognosis because of the presence of rich stromal fibrosis and acquired drug resistance. Recently, Angiotensin II type I receptor blockers such as candesartan have attracted attention for their potential anti-fibrotic activity. We examined whether candesartan could attenuate tumor proliferation and fibrosis through the interaction between gastric cancer cell line (MKN45) cells and human peritoneal mesothelial cells. Candesartan significantly reduced TGF-β1 expression and epithelial-to-mesenchymal transition-like change, while tumor proliferation and stromal fibrosis were impaired. Targeting the Angiotensin II signaling pathway may therefore be an efficient strategy for treatment of tumor proliferation and fibrosis.

A case report of anaplastic carcinoma of the pancreas with remarkable intraductal tumor growth into the main pancreatic duct

We herein report a case of anaplastic carcinoma of the pancreas with remarkable intraductal tumor growth into the main pancreatic duct. A 76-year-old male was referred to our hospital for treatment of a pancreatic tumor. Preoperative examinations revealed a poorly defined tumor in the main pancreatic duct in the body of the pancreas, accompanied with severe dilatation of the main pancreatic duct, which was diagnosed as an intraductal papillary-mucinous neoplasm. We performed distal pancreatectomy and splenectomy. The pathological examination revealed that the tumor consisted of a mixture of anaplastic carcinoma (giant cell type) and adenocarcinoma in the pancreas. There was a papillary projecting tumor composed of anaplastic carcinoma in the dilated main pancreatic duct. The patient is now receiving chemotherapy because liver metastasis was detected 12 mo after surgery. In this case, we could observe a remarkable intraductal tumor growth into the main pancreatic duct. We also discuss the pathogenesis and characteristics of this rare tumor with specific tumor growth.

Establishing a xenograft mouse model of peritoneal dissemination of gastric cancer with organ invasion and fibrosis.

BackgroundThe clinical prognosis of gastric cancer with peritoneal dissemination is poor because of its chemoresistance and rich fibrosis. While several gastric cancer cell lines have been used to establish models of peritoneal dissemination by intraperitoneal injection, most peritoneal tumors that form adopt a medullary pattern in microscopic appearance. This histological finding for the model differs from that in the clinical situation. This study was performed to demonstrate the contribution of human peritoneal mesothelial cells (HPMCs) to fibrotic tumor formation and to establish a new xenograft model with high potential for peritoneal dissemination with organ invasion and extensive fibrosis.MethodsWe established four types of xenograft model: i) intraperitoneal injection of MKN45-P cells alone (control group), ii) injection of MKN45-P cells co-cultured with HPMCs (co-cultured group), iii) scratching the parietal peritoneum (parietal group), and iv) scratching the visceral peritoneum (visceral group) with a cotton swab before injection of co-cultured cells. Fibrosis, α-smooth muscle actin expression, and organ invasion by tumor cells were all assessed by immunohistochemical examination.ResultsAll mice developed abdominal swelling with peritoneal tumors and bloody ascites. Tumors of the control and co-cultured groups were not invasive or fibrotic. Contrastingly, tumors of the scratch groups exhibited rich stromal fibrosis and possessed increased α-smooth muscle actin (α-SMA) expression. In particular, the visceral group showed edematous and spreading tumors invading the intestinal wall.ConclusionWe established a model of peritoneal dissemination with organ invasion and stromal fibrosis. Formation of peritoneal dissemination required a favorable environment for cell adhesion, invasion, and growth. This model may be useful for analyzing the pathogenesis and treatment of peritoneal dissemination of gastric cancer.

Phase I study of weekly palliative chemotherapy with low-dose third-line paclitaxel for biliary tract cancer

The prognosis of patients with unresectable and recurrent biliary tract cancer (BTC) is very poor. Although gemcitabine (GEM) plus cisplatin therapy is useful for unresectable cases, the median overall survival (OS) of the patients is <1 year, and third-line chemotherapy following failure of 5-fluorouracil (5-FU) and GEM plus cisplatin is currently unavailable. The clinical efficacy and basic effects of low-dose paclitaxel (PTX) therapy for patients with BTC was previously reported. We herein present the results of a phase I clinical trial of weekly low-dose PTX as third-line palliative chemotherapy. PTX was administered on days 1, 8, 15 and 22 of each cycle and repeated twice as follows: Level 1, 40 mg/m2; level 2, 50 mg/m2 (n=3). During the two cycles, grade 1 or 2 adverse events were observed in 3 patients, whereas dose-limiting adverse events (grade 3 or 4) were not observed. The disease control rate was 83.3% (partial response, n=3; stable disease, n=2). The OS and median survival were 15.4 and 9.0 months, respectively. In conclusion, palliative chemotherapy with low-dose PTX following failure of GEM and 5-FU was well-tolerated, safe and effective for patients with unresectable or recurrent BTCs, and the optimal dose was 50 mg/m2.

Phase I study of third-line palliative chemotherapy with low dose paclitaxel for pancreatic cancer

The prognosis of patients with unresectable or recurrent pancreatic cancers is very poor. Prior to development of nab-paclitaxel (PTX) plus gemcitabine (GEM) therapy and FOLFIRINOX therapy, there was no recommended third-line chemotherapy after 5-fluorouracil (5-FU) and GEM-based regimens. The present study conducted a Phase I clinical trial of weekly low-dose PTX as a third-line palliative chemotherapy for patients with pancreatic cancer. PTX was administered on days 1, 8, 15, and 22 of each cycle, repeated twice as follows: Level 1, 40 mg/m2 (n=6); Level 2, 50 mg/m2 (n=4). During the two cycles, three patients developed Grade 3 neutropenia in level 2; thus, the recommended dose was defined as 40 mg/m2. The disease control rate was 40.0% (stable disease, n=4). Median time to treatment failure of the four patients with stable disease was 5.5 months. In conclusion, palliative chemotherapy with low-dose PTX after failure of GEM and 5-FU is well tolerated and safe for unresectable or recurrent pancreatic cancer patients. The unique ID issues by UMIN: 000008148.

The effect of HIF-1α and PKM1 expression on acquisition of chemoresistance

Background In patients with gastric cancer, one of the greatest obstacles to effective chemotherapy is the development of chemoresistance. It has been previously reported that hypoxia-inducible factor-1 alpha (HIF-1α) is associated with acquisition of chemoresistance, and more recent studies have also noted an association of pyruvate kinase muscle 1 (PKM1) and chemoresistance. The purpose of this study was to identify the effect of HIF-1α and PKM1 expression on the development of acquired chemoresistance using a paclitaxel (PTX)-resistant gastric cancer cell line. Materials and methods A cancer cell line resistant to PTX was established from MKN45 cells by stepwise exposure to drug (rMKN45-PTX). The expressions of HIF-1α, apoptosis, vascular endothelial growth factor (VEGF), multidrug transporters and glycolytic enzyme were examined by Western blotting, enzyme-linked immunosorbent assay and immunohistochemistry. We also assessed the tumor proliferation by subcutaneous tumor and peritoneal dissemination of mouse xenograft model. Results The resistance index was 6.1 by determining as the ratio of the 50% growth inhibition (IC50) of rMKN45-PTX/IC50 of MKN45. Expression of nuclear factor kappa B and HIF-1α was increased in rMKN45-PTX cells compared with the parent cells. Expression of Bax and caspase-3 was significantly downregulated, whereas expression of Bcl-xL, P-glycoprotein, multidrug resistance-associated protein and VEGF was increased in rMKN45-PTX. The expression level of PKM1 was upregulated in rMKN45-PTX, leading to an increase in the PKM1/PKM2 ratio. Using xenograft models, we demonstrated that mouse subcutaneous tumors derived from rMKN45-PTX were significantly larger than those derived from MKN45 cells. Conclusion Under the stress of chemotherapeutic agent exposure, high expression of HIF-1α affects various downstream genes. Although the underlying mechanism is unknown, our data suggest that PKM1 is also a molecular target for gastric cancer treatment.

Low-dose eribulin mesylate exerts antitumor effects in gastric cancer by inhibiting fibrosis via the suppression of epithelial–mesenchymal transition and acts synergistically with 5-fluorouracil

Background Characterized by aggressive proliferation, extensive stromal fibrosis, and resulting drug resistance, peritoneal dissemination in gastric cancer remains associated with poor prognosis. Interaction between cancer and stromal cells accelerates tumor progression via epithelial–mesenchymal transition (EMT), which is one of the major causes of tissue fibrosis, and human peritoneal mesothelial cells (HPMCs) play important roles as cancer stroma in peritoneal dissemination. Transforming growth factor-β (TGF-β) has a pivotal function in the progression of EMT, and Smad proteins play an important role in the TGF-β signaling pathway. Eribulin mesylate (eribulin), a nontaxane microtubule dynamics inhibitor used for the treatment of advanced breast cancer, inhibits EMT changes in triple-negative breast cancer cells. We examined its ability to inhibit tumor progression and EMT changes resulting from the interaction between gastric cancer cells and HPMCs and to act synergistically with 5-fluorouracil (5-FU), a key drug for gastric cancer. Materials and methods Proliferation of gastric cancer cells and HPMCs isolated from healthy omentum was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Following gastric cancer cell/HPMC coculture, EMT markers were detected by immunofluorescence, immunohistochemistry, and Western blotting; invasion assays were performed; and TGF-β and Smad phosphorylation were assessed by Western blotting and enzyme-linked immunosorbent assay. A mouse fibrotic tumor xenograft model was established using gastric cancer cell/HPMC cocultures. The effect of eribulin and/or 5-FU was tested in each case. Results Eribulin significantly suppressed gastric cancer cell proliferation and EMT changes in MKN-45 gastric cancer cells and HPMCs induced by their interaction in vitro. Eribulin inhibited EMT at much lower concentrations (≥0.5 nM for MKN-45 and ≥0.1 nM for HPMCs) than its half maximal inhibitory concentrations (2.2 nM for MKN-45 and 8.1 nM for HPMCs), and this resulted, at least partly, from the downregulation of TGF-β/Smad signaling. Eribulin administration of ≥0.1 mg/kg suppressed tumor progression (0.1 mg/kg, p=0.02), and fibrosis was inhibited by lower dose (0.05 mg/kg, p=0.008) in the xenograft model. Furthermore, 0.05 mg/kg administration with 5-FU brought about synergistic antitumor effects (p=0.006). Conclusion Low-dose eribulin combined with 5-FU might be a promising therapy for peritoneal dissemination in gastric cancer.

Von Willebrand Factor Deposition and ADAMTS-13 Consumption in Allograft Tissue of Thrombotic Microangiopathy-like Disorder After Living Donor Liver Transplantation: A Case Report

BACKGROUND Thrombotic microangiopathy (TMA) pathogenesis after living donor liver transplantation (LDLT) is thought to be caused by release of unusually large von Willebrand factor multimers (UL-vWFMs) resulting from sinusoidal endothelial cell damage and induction of platelet adhesion and aggregation. A decrease in a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13 (ADAMTS-13) that cleave UL-vWFMs might cause excessive UL-vWFMs activity and result in platelet thrombus formation. However, this phenomenon has not undergone a full pathologic assessment. PROCEDURES A 60-year-old man was diagnosed with hepatitis C-related end-stage cirrhosis. His son was the donor, and he underwent LDLT. On postoperative day 44, his laboratory findings met most TMA diagnostic criteria, and he was diagnosed with TMA-like disorder (TMALD). Localization of CD42b as a platelet marker, vWF, and ADAMTS-13 in allograft tissue of this patient were evaluated using immunohistochemistry. RESULTS CD42b expression was observed as platelet aggregates attached to hepatocytes or within the hepatocyte cytoplasm, a morphology called extravasated platelet aggregation (EPA). vWF expression was observed mainly as deposited compact clusters, and ADAMTS-13 expression resembled distinct dots throughout the liver tissue. CONCLUSION These findings suggest that EPA indicated sinusoidal endothelial cell damage followed by detachment, and vWF deposition resulted from UL-vWFM oversynthesis. ADAMTS-13 might be consumed in the allograft tissue to cleave UL-vWFMs, but ADAMTS-13 levels might be insufficient to cleave all the deposited UL-vWFMs. We present the case of an LDLT recipient diagnosed with TMALD using blood tests, which showed the presence of TMA pathogenesis in the allograft.