Retroperitoneal Liposarcoma with Multilocular Cysts.

In this study, we describe a 60-year-old man with a giant retroperitoneal liposarcoma with multilocular cysts. He was admitted to our hospital because of a 5-month history of abdominal distention. Abdominal computed tomography revealed a giant lobulated cystic mass occupying the retroperitoneal space that contained partially solid fat components. Magnetic resonance imaging indicated that this complex mass exhibited a low signal intensity on a T1-weighted image, whereas it exhibited a high and focally intermediate signal intensity on a T2-weighted image. This patient was diagnosed with a mucinous type of retroperitoneal sarcoma, which was then resected. During surgery, the tumor was isolated from the retroperitoneum and other organs, but the detachment was required only because of fixation around the left external iliac artery. The histological diagnosis was a well-differentiated liposarcoma with multilocular cysts that contained old bloody, serous, and mucinous fluids, which are a rare phenomenon in liposarcoma. This case indicates that retroperitoneal liposarcoma should also be considered as a differential diagnosis of retroperitoneal cystic mass.

Paget's disease derived in situ from reserve cell hyperplasia, squamous metaplasia, and squamous cell carcinoma of the esophagogastric junction: a case report.

BACKGROUND: Extramammary Paget's disease (EMPD) of the esophagus is a rare tumor, with most cases originating from invasive adenocarcinoma of the esophagus. Pure esophageal Paget's disease, in which no underlying invasive carcinoma component is present, is extremely rare. In this report, we describe a case of EMPD of the esophagogastric junction with no evidence of invasive carcinoma. CASE PRESENTATION: An 81-year-old Japanese woman with a 2-week history of abdominal distension presented to our hospital for assessment. Endoscopic examination revealed a mild elevated granular lesion, with a slightly depressed irregular mucosa, in the distal esophagus, with EMPD confirmed by biopsy. Thoracoscopic esophagectomy with lymph node dissection was performed, with Paget cells observed on microscopic examination in the lower part of the esophageal epithelium. Only a few Paget cells stained positively for PAS/Alcian blue. Immunohistochemically, negative staining for CK5 and p63 were identified in the Paget cells, with positive staining for CK7. Furthermore, an intraepithelial squamous cell carcinoma, with squamous metaplasia and reserve cell hyperplasia, was observed in the gastric mucosa of the esophagogastric junction, adjacent to the Paget cells. CONCLUSIONS: EMPD of the esophagus is a rare disease. We report a case of EMPD that was probably derived from a gastric squamous cell carcinoma, with squamous cell metaplasia and reserve cell hyperplasia, in the esophagogastric junction, which, to our knowledge, is the first report of this type of EMPD in the clinical literature.

Successful surgical treatment of a spontaneous rupture of the esophagus diagnosed two days after onset.

Esophageal perforation is a relatively uncommon disease with a high rate of mortality and morbidity. Delay in the diagnosis and treatment occurs in more than 50% of cases, leading to a mortality rate of 40-60%. Primary repair is generally considered the gold standard for patients who present within the first 24 h following perforation of the esophagus. In this paper, we present a case of successful surgical treatment of spontaneous rupture of the esophagus that was diagnosed 2 days after onset. The patient was a 42-year-old man admitted to internal medicine with a diagnosis of pleuritis and complaining of chest and back pain. The next day, computed tomography revealed left-sided pleural effusion and mediastinal emphysema. An esophagogram revealed extravasation of the contrast medium from the lower left esophagus to the mediastinal cavity. These results confirmed a rupture of the esophagus, and an emergency left thoracotomy was performed. The perforation was repaired with a single-layered closure and was covered with elevated great omentum obtained by laparotomy. The patient was discharged 23 days after the first surgery. In conclusion, primary repair surgery must be selected as the best treatment beyond 24 h if the patient's general state was stable and there was no evidence of clinical sepsis.

Liver hemorrhage due to idiopathic peliosis hepatis successfully treated with hepatic artery embolization.

Peliosis hepatis is an extremely rare condition that may cause fatal hepatic hemorrhage and liver failure. We report a case of liver hemorrhage due to idiopathic peliosis hepatis. A 60-year-old woman was admitted to our hospital with slight right hypochondriac pain. She went into hemorrhagic shock, and computed tomography (CT) showed multiple low-density areas in the right liver with massive subcapsular blood collection. Selective transfemoral arteriography of the celiac artery revealed no signs of vascular malformation or tumor stain, but showed signs of pooling in the right posterior segmental artery. The artery was embolized with particles of gelatin sponge, and hemostatic control was successful. Although peliosis hepatis is extremely rare, the diagnosis is significant because of its urgent clinical status, and transarterial embolization is a useful and minimally invasive procedure for liver hemorrhage due to peliosis hepatis.

HOMER2 binds MYO18B and enhances its activity to suppress anchorage independent growth.

MYO18B is a class XVIII myosin, cloned as a tumor suppressor gene candidate. To investigate the mechanisms of MYO18B-dependent tumor suppression, MYO18B-interacting proteins were searched for by a yeast two-hybrid screen. HOMER2, a Homer/Ves1 family protein, was identified as a binding partner of MYO18B. These proteins co-localized in the regions of membrane protrusion and stress fiber, which are known as ones with filamentous actin-rich structures. Expression of HOMER2 enhanced the ability of MYO18B to suppress anchorage-independent growth. These results indicate that HOMER2 and MYO18B cooperate together in tumor suppression.

Activation of the AKT and STAT3 pathways and prolonged survival by a mutant EGFR in human lung cancer cells.

To clarify the pathogenic and biological significance of EGFR mutations in lung cancer, we compared the status of ERBB family receptors, their downstream signal transductions and biological phenotypes between lung cancer cell lines with mutant and wild type EGFR. We initially analyzed expression and phosphorylation of ERBB family receptors and their major downstream proteins, AKT, p44/42 MAPK and STAT3, in a series of lung cancer cell lines with or without EGFR mutation. The expression levels of EGFR as well as of ERBB2 and ERBB3 proteins in cells with EGFR mutation tended to be higher than those in cells with wild type EGFR. There was no difference in stability between mutant and wild type EGFR proteins. EGF induced phosphorylation of EGFR, AKT, p44/42 MAPK and STAT3 to various extents, but the level of induction was not associated with the existence of EGFR mutation. These results implied that the activation of AKT, p44/42 MAPK and STAT3 signaling transmitted by EGFR would be critical for the growth and survival of lung cancer cells, but specific features of mutant EGFR in lung cancer cells was not discriminated by these approaches. We therefore performed transfection studies using PC-13 cells with no detectable endogenous EGFR expression. Exogenous expression of wild type and mutant EGFR (delE746-A750) in the cells revealed that only in the mutant EGFR transfected cells, EGFR itself as well as AKT and STAT3 were highly phosphorylated after 24h of serum deprivation. The survival time of mutant EGFR transfected cells was prolonged under serum-free culture conditions, but not under standard culture conditions with 10% serum. These results suggest that cells with a mutant EGFR survive through the activation of the AKT and/or STAT3 pathways, even in low EGF microenvironments. This specific property due to EGFR mutation could be an important step of multistage lung cancer progression.

MYO18B interacts with the proteasomal subunit Sug1 and is degraded by the ubiquitin-proteasome pathway.

MYO18B is a class XVIIIB unconventional myosin encoded by a candidate tumor suppressor gene. To gain insights into the cellular function of this protein, we searched for MYO18B-interacting proteins by a yeast two-hybrid screen. Sug1, a 19S regulator subunit of the 26S proteasome, was identified as a binding partner of the C-terminal tail region of MYO18B. The association of MYO18B with Sug1 was further confirmed by GST pull-down, co-immunoprecipitation, and immunocytochemistry. Furthermore, proteasome dysfunction by a proteasome inhibitor or siRNA-mediated knock-down of Sug1 caused the up-regulation of MYO18B protein and MYO18B was polyubiquitinated in vivo. Collectively, these results suggested that MYO18B is a substrate for proteasomal degradation.

Restored expression of the MYO18B gene suppresses orthotopic growth and the production of bloody pleural effusion by human malignant pleural mesothelioma cells in SCID mice.

Malignant pleural mesothelioma (MPM) is closely related to exposure to asbestos, and a rapid increase in the number of MPM patients is therefore estimated to occur from 2010 to 2040 in Japan. Because MPM is refractory to conventional chemotherapy and radiotherapy, the prognosis of MPM patients is extremely poor. MYO18B, a novel member of the myosin family, is a tumor suppressor gene isolated from a homozygously deleted region at 22q12.1 in a lung cancer cell line. The inactivation of the MYO18B gene plays an important role in several malignant diseases. However, the role of MYO18B in the progression of MPM is still unknown. Six different human MPM cell lines were used in this study. Western blot revealed that none of the cell lines expressed a detectable level of MYO18B protein. One of the MPM cell lines, EHMES-10, was transfected with the MYO18B gene. We found that a restored expression of the MYO18B protein in EHMES-10 cells resulted in the inhibition of their anchorage-independent growth and motility in vitro. In addition, it also inhibited their ectopic (subcutaneous space) and orthotopic (thoracic cavity) growth in SCID mice, in association with an increased degree of cell apoptosis. Furthermore, it also suppressed the production of bloody pleural effusion after orthotopic injection. These findings suggest that the restored expression of MYO18B may be a useful therapeutic strategy for the treatment of locally advanced MPM in humans.

Genetic and epigenetic alterations of the candidate tumor-suppressor gene MYO18B, on chromosome arm 22q, in colorectal cancer.

Allelic imbalance (AI) on chromosome arm 22q has been detected in 20%-40% of colorectal cancers, suggesting that this chromosome arm has a tumor-suppressor gene involved in colorectal carcinogenesis. Recently, we isolated a candidate tumor-suppressor gene, MYO18B, at 22q12.1, that is deleted, mutated, and hypermethylated in more than 50% of lung cancers. In the present study, we analyzed genetic and epigenetic alterations of the MYO18B gene in colorectal cancers. AI at the MYO18B locus was detected in 16 of 43 (40%) informative cases. Mutations of the MYO18B gene were detected in 2 of 11 (18%) cell lines and 1 of 47 (2%) surgical specimens. Nine of 11 (82%) cell lines showed reduced MYO18B expression, which was restored in all 9 by treatment with 5-aza-2'-deoxycytidine and/or trichostatin A (TSA). Although hypermethylation of the promoter CpG island for MYO18B was not detected, a significant correlation was observed between the level of MYO18B expression and the level of acetylation of histones H3 and H4 in 6 cell lines with and without TSA treatment. Thus, it was suggested that MYO18B is inactivated in a considerable fraction of colorectal cancers by several mechanisms, especially silencing by histone deacetylation and/or AI. Furthermore, restoration of MYO18B expression in colorectal cancer cell lines HT29 and DLD-1 suppressed anchorage-independent growth, whereas it did not affect the growth rate in vitro. These results suggest that genetic and epigenetic inactivation of the MYO18B gene play an important role in colorectal carcinogenesis.

Correlation between histone acetylation and expression of the MYO18B gene in human lung cancer cells.

Recently, we isolated a candidate tumor-suppressor gene, MYO18B, which was inactivated in approximately 50% of human lung cancers by deletion, mutation, and promoter methylation. However, more frequent reduction or loss of MYO18B expression and restoration of MYO18B expression by trichostatin A (TSA) treatment suggested the contribution of other mechanisms, especially histone deacetylation, for epigenetic inactivation of the MYO18B gene. In this study, we examined histone modification of the promoter region of the MYO18B gene in 8 human lung cancer cell lines by a chromatin immunoprecipitation assay. In 6 of 7 cell lines with reduced or silenced MYO18B expression, the levels of histones H3 and H4 acetylation surrounding the MYO18B promoter region were lower than those in a cell line with MYO18B expression. By treatment with TSA, the levels of histone H3 and H4 acetylation were increased in all 6 cell lines whose MYO18B expression was restored by TSA, whereas neither H3 nor H4 acetylation was increased in cells whose MYO18B expression was not restored by TSA. Significant correlations were observed between the levels of histone H3/H4 acetylation and MYO18B expression. These results suggest that acetylation of both histones H3 and H4 contributes to regulation of MYO18B expression in lung cancer cells and that histone deacetylation surrounding the promoter region plays an important role in MYO18B silencing and is involved in lung carcinogenesis.

Biological properties and gene expression associated with metastatic potential of human osteosarcoma.

Lung metastasis has a great influence on the prognosis of patients with osteosarcoma. We previously established two high-metastatic sublines, M112 and M132, from the HuO9 human osteosarcoma cell line by in vivo selection. In this study, we newly isolated a high-metastatic subline, H3, and three low-metastatic sublines, L6, L12 and L13, from HuO9 by the dilution plating method. Three high-metastatic sublines produced more than 200 metastatic nodules in the lung, while three low-metastatic sublines produced no or few nodules after injection of 2 x 10(6) cells into the tail vein of nude mice. There were significant differences in the motility and invasiveness between high- and low-metastatic sublines, whereas the growth rates in vitro and the tumorigenicity in vivo showed no correlation with their metastatic abilities. Early adherence to culture plates was significantly lower in two of three low-metastatic sublines, which occupied smaller surface areas on the culture plates than other sublines did. Comparison of the expression of 637 cancer-related genes by cDNA microarray revealed that seven genes were differentially expressed between high- and low-metastatic sublines. Among them, five genes (AXL, TGFA, COLL7A1, WNT5A, and MKK6) were associated with adherence, motility, and/or invasiveness. These results suggest that the differences in motility/invasiveness and adhesive abilities are key determinants of lung metastasis in osteosarcoma.

Genetic alterations responsible for metastatic phenotypes of lung cancer cells.

It is now widely accepted that human carcinogenesis is a multi-step process and phenotypic changes during cancer progression reflect the sequential accumulation of genetic alterations in cells. Thus, in order to understand the process of acquisition of metastatic phenotypes in cancer cells, it is indispensable to identify genes whose alterations accumulate during cancer progression and correlate with metastatic phenotypes of cancer cells. For this reason, we have been searching for genes that are preferentially altered in metastatic lung cancer cells and have activities to regulate their metastatic potentials. In lung cancer, both the p16INK4A/RB and p53 genes are frequently inactivated and are critical determinants for the regulation of cell growth and apoptosis. However, it still remains unclear whether these genes are also involved in the regulation of metastatic potential in lung cancer cells. Recently, we identified a novel myosin family gene, MYO18B, from the chromosome 22q12.1 region which shows frequent loss of heterozygosity in advanced lung cancer, and we found that this gene is inactivated in approximately 50% of lung cancers by deletions, mutations and methylation. Furthermore, restoration of MYO18B expression suppressed anchorage-independent growth of lung cancer cells. Thus, it was indicated that the MYO18B gene is a strong candidate for a metastasis suppressor gene of human lung cancer. Further functional and biological studies of the MYO18B gene will help us understand the molecular pathway of human lung cancer progression.

Pathogenetic and biologic significance of TP14ARF alterations in nonsmall cell lung carcinoma.

The INK4a/ARF locus on human chromosome band 9p21 carries two tumor suppressor genes, TP14ARF and TP16INK4a, and both are frequently inactivated in nonsmall cell lung carcinoma (NSCLC. TP14ARF and TP16INK4a play important roles in the TP53 and RB tumor suppressor pathways, respectively. To elucidate the genetic and epigenetic status of the TP14ARF and TP16INK4a genes in NSCLC, we comprehensively analyzed mutations, homozygous deletions, methylations in the CpG regions, and expression of the TP14ARF and TP16INK4a genes in 31 NSCLC cell lines. TP16INK4a (84%) was inactivated more frequently than TP14ARF (55%). Moreover, p16INK4a was inactivated in all 17 cell lines with TP14ARF inactivation. Three cell lines with base substitutions in exon 2 resulted in missense mutations of TP16INK4a but silent mutations of TP14ARF. There was a case of mutation in exon 1alpha unique to TP16INK4a, but not a mutation in exon 1beta unique to TP14ARF. The TP16INK4a gene was methylated in 6 cell lines, but the TP14ARF gene was not methylated in any cell line. Unlike a mutually exclusive relationship for inactivation between TP16INK4a and RB, TP14ARF and TP53 did not show such a relationship (P = 0.61, Fisher exact test). Thus, the present results indicate the TP16INK4a gene to be the primary target of INK4a/ARF locus alterations. Transient TP14ARF expression induced G1 arrest in the cells with wild-type TP53, but not in the cells with mutated TP53. Thus, the pathogenetic and biologic significance of TP14ARF inactivation is different between NSCLC cells with wild-type TP53 and those with mutated TP53.

Establishment of human osteosarcoma cell lines with high metastatic potential to lungs and their utilities for therapeutic studies on metastatic osteosarcoma.

Relevant animal models for metastasis of osteosarcoma is needed to understand the biology and to develop the treatment modality of metastasis of human osteosarcoma. Therefore, we screened six human osteosarcoma cell lines for metastatic ability in nude mice. The HuO9 cell line was identified as being metastatic to the lung after intravenous injection. We established two sublines, HuO9-M112 and HuO9-M132, with high metastatic potential to the lung from the parental HuO9 cells by in vivo selection. There were no differences between these two sublines and the parental cells in the growth rate in vitro and the tumorigenicity after subcutaneous injection in nude mice, however, mice injected with the metastatic sublines became moribund earlier than mice injected with the parental HuO9 cells did. Thus, adriamycin (ADR) and recombinant interleukin-12 (IL-12) were administered to mice injected with the HuO9-M112 subline to suppress experimental lung metastases. Production of lung colonies was significantly suppressed and the prognoses of mice were significantly improved by both ADR and IL-12 treatments. These results indicate that both ADR and IL-12 are effective agents against pulmonary metastatic osteosarcoma, and that these sublines are useful for studies on the biological behavior and treatment of pulmonary metastatic osteosarcoma.

MYO18B, a candidate tumor suppressor gene at chromosome 22q12.1, deleted, mutated, and methylated in human lung cancer.

Loss of heterozygosity on chromosome 22q has been detected in approximately 60% of advanced nonsmall cell lung carcinoma (NSCLC) as well as small cell lung carcinoma (SCLC), suggesting the presence of a tumor suppressor gene on 22q that is involved in lung cancer progression. Here, we isolated a myosin family gene, MYO18B, located at chromosome 22q12.1 and found that it is frequently deleted, mutated, and hypermethylated in lung cancers. Somatic MYO18B mutations were detected in 19% (14/75) of lung cancer cell lines and 13% (6/46) of primary lung cancers of both SCLC and NSCLC types. MYO18B expression was reduced in 88% (30/34) of NSCLC and 47% (8/17) of SCLC cell lines. Its expression was restored by treatment with 5-aza-2'-deoxycytidine in 11 of 14 cell lines with reduced MYO18B expression, and the promoter CpG island of the MYO18B gene was methylated in 17% (8/47) of lung cancer cell lines and 35% (14/40) of primary lung cancers. Furthermore, restoration of MYO18B expression in lung carcinoma cells suppressed anchorage-independent growth. These results indicate that the MYO18B gene is a strong candidate for a novel tumor suppressor gene whose inactivation is involved in lung cancer progression.

E-cadherin gene variants in gastric cancer families whose probands are diagnosed with diffuse gastric cancer.

To identify germline E-cadherin mutations responsible for the predisposition to diffuse gastric cancer (DGC) among the Japanese, we screened 17 patients with familial aggregation of gastric cancer by sequencing analysis. All the patients were diagnosed with DGC and had at least 1 sibling with gastric cancer. Two novel E-cadherin gene variants were detected. One was detected in 1 patient only and associated with an amino acid substitution (Val/Met) at codon 832 in the region essential for binding to beta-catenin. The M832 variant was detected not only in the proband but also in 2 other gastric cancer patients in the family. Immunohistochemical analysis of gastric cancer tissue from the proband revealed that E-cadherin expression was markedly reduced and beta-catenin expression was also reduced in cancer cells. However, no significant difference in the activity of beta-catenin binding was detected between the M832 variant and V832 wild-type E-cadherin in immunofluorescence and immunoprecipitation/Western blot analyses. The other was detected in 5 patients and was located in the splice donor site (IVS1+6T/C); however, RT-PCR analysis indicated that the IVS+6C variant did not cause an aberrant splicing. Thus, the M832 variant could be a germline mutation causative of familial aggregation of DGC, although further functional studies are needed to understand the pathogenic significance of this variant.