Regeneration of injured intestinal mucosa is impaired in hepatocyte growth factor activator-deficient mice.

BACKGROUND AND AIMS: Hepatocyte growth factor activator (HGFA) is a serum proteinase that specifically converts an inactive single-chain form of hepatocyte growth factor (HGF) into an active 2-chain form. HGFA is produced in its precursor form and then activated in injured tissues. To address the precise role of HGFA and to investigate the mechanisms of HGF activation in injured tissues, we generated mice deficient in HGFA. METHODS: HGFA-deficient mice were generated using targeted gene disruption. The regenerating process of intestinal mucosa damaged by oral administration of dextran sodium sulfate (DSS) or by rectal administration of acetic acid was examined in both HGFA-deficient and control mice. HGF processing activity was analyzed using Western blotting and an HGF activation assay. RESULTS: Homozygous mutant mice were viable and fertile without obvious abnormalities. When mice were treated with 3% DSS in drinking water for 6 days followed by distilled water without DSS, 72% of HGFA-deficient mice died through day 12 while 75% of control mice survived injury. Similar results were also observed in the acetic acid-induced intestinal injury; the survival rate was 36.6% in HGFA-deficient mice and 84.2% in control mice. In HGFA-deficient mice, the injured mucosa was not sufficiently covered by regenerated epithelium and the activation of HGF was impaired in the injured colon. CONCLUSIONS: These results indicate that HGFA is required for repair of injured intestinal mucosa but is not essential for normal development during embryogenesis or after birth.

Complex formation of IQGAP1 with E-cadherin/catenin during cohort migration of carcinoma cells. Its possible association with localized release from cell-cell adhesion.

In histopathological sections, it is frequently observed that carcinoma cells invade the stroma as coherent cell nests rather than single cells. We have called this type of movement "cohort migration (CM)" and developed an in vitro model, in which human colon carcinoma cells move as coherent cell sheets when stimulated with hepatocyte growth factor/scatter factor (HGF/SF). In this CM model, localized release from cell-cell adhesion at the lower portion of cells is essential for cell movement. Its mechanism was investigated in this study with special reference to the E-cadherin/catenin complex (Ecc) and IQGAP1. IQGAP1 is a target molecule of Cdc42 and Rac1 and negatively regulates the Ecc-based cell-cell adhesion by dissociating alpha-catenin, a key molecule that links Ecc to actin cytoskeleton, from Ecc. In our study, the amount of IQGAP1 bound to Ecc increased in migrating cells in association with a decrease in the alpha-catenin level in Ecc. In accordance with this, IQGAP1 showed a shift from the cytosol to the membrane fraction. Moreover, confocal laser microscopic study demonstrated the localization of IQGAP1 at the membranes of the lower portion of migrating cells, where cell-cell adhesion was specifically disrupted during CM. Furthermore, when HGF/SF-induced CM was enhanced with pre-coated extracellular matrix (ECM) components, the level of IQGAP1 in Ecc increased more than that caused by HGF/SF alone. On the contrary, when CM was inhibited by interrupting cell-ECM interaction, the level of IQGAP1 in Ecc did not increase despite HGF/SF stimulation. Taken together, these results indicate close association of IQGAP1 with localized disruption of cell-cell adhesion during CM and that modulation of CM by cross-talk between signals induced by HGF/SF and cell-ECM interactions also involves IQGAP1-related mechanisms.

Cytology of primary cutaneous Langerhans cell histiocytosis with a malignant phenotype. A case report.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a proliferative disorder of Langerhans cells, but the nature of LCH, whether reactive, benign, or malignant and neoplastic, is controversial. We encountered a case of LCH showing a malignant phenotype initially localized in the skin of an elderly woman. Since there is no other report on the cytologic appearance of primary cutaneous LCH or on LCH with a malignant phenotype, we compared the cytologic features of this case with those of benign cases at other sites reported in the literature. CASE: A 74-year-old woman presented with a gradually enlarging and partially ulcerated skin lesion expanding both sides of her right hand. On histologic and ultrastructural analyses of surgically resected tissue, we diagnosed the lesion as Langerhans cell histiocytosis originating in the skin. Although the patient had no recurrence or metastases for six months after surgical resection of the primary skin lesion and radiation therapy, the tumor extended multisystemically, and the patient died of multiple organ failure 14 months after the initial diagnosis. CONCLUSION: Imprint and scrape cytology of multiple skin lesions six months after surgery was useful in immediately diagnosing the recurrent LCH. The tumor cells had indented, twisted or grooved nuclei, and some had intranuclear inclusions. Immunocytochemically the cells were positive for CD1a and S-100 protein. Numerous eosinophils were seen in the background.

Hydroxyapatite block for use in posterolateral lumbar fusion: a report of four cases.

Autologous bone grafts for posterolateral lumbar fusion are harvested from the iliac crests. Recently, several alternatives to autologous bone have been evaluated (such as graft substitutes, graft extenders, or both) with variable results. However, no clinical long-term studies have validated the efficacy of these techniques in posterolateral lumbar fusion. This study evaluated radiographic and histologic findings in four patients (mean age, 66 years) during the first 5 years after posterolateral fusion with an hydroxyapatite block. The mean followup was 7 years 1 month. Radiologic evaluation was by plain radiographs and computed tomography scans. Histologic evaluation was done in one patient. Capillaries extended into the porous structure of the hydroxyapatite substrate, and some of the pores were replaced by newly formed bone tissue. The long-term results of graft substitutes were stable and hydroxyapatite appeared to have some potential to achieve union in posterolateral lumbar fusion. However, hydroxyapatite block alone has not functioned effectively as a complete graft substitute in posterolateral lumbar fusion. Thus, a suitable osteogenic material is required to induce the formation of new bone and achieve a solid union.

Diffuse pagetoid squamous cell carcinoma of the esophagus combined with choriocarcinoma and mucoepidermoid carcinoma: an autopsy case report.

Esophageal squamous cell carcinoma in situ (SCCIS) with diffuse pagetoid features is a recently recognized rare variant of squamous cell carcinoma. A histopathological study of a specimen from a 70-year-old male Japanese patient is reported. The patient died of respiratory failure due to rapidly progressing metastatic pulmonary tumors of unknown origin 73 days after the onset of hemosputum. Autopsy disclosed widespread metastasis of choriocarcinoma in the absence of tumors of the testes or other common sites of germ cell tumors. Elevation of human chorionic gonadotropin (hCG-beta) levels was later detected in the stored serum. Serial histological evaluation of the entire esophagus revealed a small primary site of choriocarcinoma in a background of diffuse SCCIS, mainly of pagetoid type, accompanied by several small foci of submucosally invasive squamous cell carcinoma and primary mucoepidermoid carcinoma. These stimulated nodal metastasis independently of the choriocarcinoma. The SCCIS did not alter the gross mucosal appearance. This is the first reported case of diffuse pagetoid SCCIS combined with choriocarcinoma. Morphological findings and previous studies suggest that the extensive SCCIS of the esophagus resulted from pagetoid spread of tumor cells. The invasive squamous cell carcinoma, mucoepidermoid carcinoma and choriocarcinoma are suggested to have originated from the overlying SCCIS.

Immunohistochemical analysis of IQGAP1 expression in human colorectal carcinomas: its overexpression in carcinomas and association with invasion fronts.

In histopathological sections, it is frequently observed that carcinoma cells move in and invade the stroma as coherent cell nests, rather than single cells. We have called this type of movement 'cohort migration (CM)' and developed an in vitro model, in which human colon adenocarcinoma cells move as coherent cell sheets when stimulated with naturally occurring motogenic factor, hepatocyte growth factor/scatter factor (HGF/SF). In this CM model, localized release from cell-cell adhesion is essential for cell movement. Recently, we have shown that IQGAP1, a target molecule of Cdc42 and Rac1 small GTPases, is involved in this localized release from the E-cadherin-based cell-cell adhesion during CM. In this study, we examined expression of IQGAP1 immunohistochemically in human colorectal tissues and found that IQGAP1 was overexpressed in carcinoma tissues compared with normal counterparts. Within the carcinoma tissue, IQGAP1 tended to be expressed more at the invasion front than at the upper portions, and higher levels of expression were observed in deeper two-thirds of carcinoma tissues than in the superficial one-third. This expression pattern showing stronger signals in deeper portions was most apparent in advanced carcinomas that invaded into the subserosa. These findings supported a role of IQGAP1 in colon carcinoma invasion.

Expression of hepatocyte growth factor activator inhibitor type 2 (HAI-2) in human testis: identification of a distinct transcription start site for the HAI-2 gene in testis.

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) and type 2 (HAI-2) are recently identified integral membrane Kunitz-type proteinase inhibitors. They have important regulatory roles in pericellular activation of hepatocyte growth factor/scatter factor (HGF/SF) which is critically involved in the development and regeneration of various tissues. Recent reports suggest that HGF/SF is also involved in testicular development and spermatogenesis. In this study, we analyzed the expression of HAIs in the testis. In human testis, HAI-2 was strongly expressed whereas HAI-1 mRNA was hardly detectable. Of interest was the observation that the mRNA size of HAI-2 was shorter in the testis (1.2 kb) than those in the other tissues such as placenta (1.5 kb). Subsequent experiments revealed that there are two major transcription start sites of the HAI-2 gene, which are -30 bp and -360 bp upstream from the translation initiation ATG codon. Although the latter site appeared to be mainly used in the placenta and other non-testicular organs, only the former site is used in testis, resulting in the -300 bp shorter mRNA. An immunohistochemical study using a specific monoclonal antibody raised against human HAI-2 protein indicated that HAI-2 is expressed exclusively in primary spermatocytes. These results suggest a distinct regulation of HAI-2 gene expression in testis and that HAI-2 may play a role in the process of spermatogenesis.