Lisofylline and lysophospholipids ameliorate experimental colitis in rats

BACKGROUND

Intestinal inflammatory processes initiate a chain reaction in which membrane-bound lipids generate eicosanoids and phospholipids. Bioactive lipid mediators play a pivotal role in the pathogenesis of intestinal inflammation and colonic mucosa from patients with inflammatory bowel disease contains high levels of phospholipids. Therefore, we investigated the effects of lysophosphatidic acid and lysophosphatidylethanolamine, two natural occurring phospholipids and lisofylline, which decreases lipid peroxidation, in an in-vivo model of intestinal inflammation.

METHODS

Colitis was induced by rectal administration of ethanol and trinitrobenzene sulfonic acid in rats. Rats were treated once daily with either lysophosphatidic acid or lysophosphatidylethanolamine rectally or twice daily intraperitoneally with lisofylline following induction of colitis. Rats were sacrificed after 7 days and the effect of lysophosphatidic acid, lysophosphatidylethanolamine, and lisofylline on colonic damage and inflammation were assessed using standardized macroscopical and histological injury scores.

RESULTS

Treatment with lysophosphatidic acid, lysophosphatidylethanolamine, and lisofylline significantly reduced the degree of inflammation and necrosis in the distal colon compared to control rats. In addition, the weight loss was significantly less in the treatment groups compared to controls. Histological studies revealed a significant reduction of epithelial damage and colonic inflammation.

CONCLUSION

The administration of anti-inflammatory lysophospholipids and suppression of proinflammatory lipid metabolites by lisofylline may provide new approaches to ameliorate intestinal inflammation.

Expression of gap junction proteins (connexin 26, 30, 32, 43) in normal mucosa, hyperkeratosis and carcinoma of the human larynx

INTRODUCTION

Gap junction proteins (connexins = Cx) form transmembrane channels and mediate the transfer of small molecules and ions between the cytoplasm of adjacent cells. Most tissues express several Cx isoforms. The precise combination might play an important role in the maintenance of cell differentiation. Human carcinogenesis is accompanied by aberrant expression and function of Cx. While the larynx is a target organ for many tumor promoters, no data on Cx expression in laryngeal mucosa are available. The goal of the study was to observe the expression of different Cx (Cx26, -30, -32 and -43) in the normal mucosa, hyperkeratoses and carcinomas of the human larynx.

METHOD

The immunofluorescence method was performed in normal (n = 7) and dysplastic (n = 6) laryngeal mucosa and in squamous cell carcinoma (n = 7) using affinity-purified polyclonal rabbit antibodies against the 4 Cx isoforms and FITC-conjugated secondary antibodies.

RESULTS

The immunofluorescence staining of the normal human vocal fold's epithelium showed the expression of Cx26 and Cx30 in the parabasal and intermediate layers, whereas Cx43 was localized in the basal, parabasal and lower intermediate layers. Cx epitopes could not be found in the upper layers. The precanceroses showed a similar expression of the Cx compared to normal laryngeal epithelium. Due to the higher degree of staining observed in dysplastic specimens, a hyperexpression of Cx26, -30 and -43 could be assumed. The squamous cell carcinomas were characterized by inhomogeneous staining for Cx26, -30 and -43. Regions of intensive expression alternated with regions of no expression. Cx32 could not be observed by immunofluorescence staining in laryngeal tissue.

CONCLUSION

In immunohistochemical terms, there was no alteration of the expression of Cx isoforms during carcinogenesis in the laryngeal epithelium. These results do not exclude a loss of functional intercellular gap junction communication by posttranslational modifications of Cx isoforms or disturbed Cx integration into the gap junction channel. Further studies should investigate potential defective gap junctional intercellular communication in cancer cells based on molecular studies.

Influence of linomide on local tumor growth and metastasis of the human hormone-resistant prostate cancer cell line PC3 in an orthotopic model

OBJECTIVE

It has been demonstrated that quinoline-3-carboxamide, linomide, inhibited angiogenesis and reduced the volume of tumors grown from human hormone-resistant prostate cancer cell lines after subcutaneous implantation in mice. However, subcutaneous xenograft models may not mimic human conditions due to the absence of prostatic stromal cells at the ectopic site. Therefore, we investigated the influence of linomide on local tumor growth and metastasis of the human hormone-resistant prostate cancer cell line PC-3 in an orthotopic model.

METHODS

In 30 athymic nude mice, 5x10(5) PC-3 cells were injected into the dorsal prostate after surgical exposure. After 7 days, group 1 (n = 15 mice) received linomide 100 mg/kg/day in the drinking water (per os). The other 15 mice (group 2) served as controls. All mice were sacrificed after 38 days followed by macroscopical and histological evaluation of local tumor growth and metastasis. Microvessel density was determined by immunohistochemical staining for von Willebrand factor as well as silver staining followed by morphometric analysis in an area of highest vessel density.

RESULTS

In the control group, local tumorigenicity and locoregional lymph node metastasis was 100%. The mean weight of the local tumor was 894 mg (395- 1,261 mg). The mean transversal diameter of the lymph node metastases was 4.0 mm (1.5-5. 4 mm). In the treatment group, local tumor growth and lymph node metastasis was 100% with a mean local tumor weight of 869 mg (232-1, 131 mg) and a mean lymph node metastasis diameter of 4.6 mm (1.3-5.9 mm). Microvessel density of the local tumor in the control and treatment group did not differ significantly.

CONCLUSION

Contrary to the results reported in subcutaneous animal models, linomide per os has no effect on net tumor growth and metastasis after orthotopic implantation of the human hormone-resistant prostate cancer cell line PC-3 in nude mice.

Modulation of intestinal epithelial wound healing in vitro and in vivo by lysophosphatidic acid

BACKGROUND & AIMS

Lysophosphatidic acid (LPA) is assumed to play an important role in the modulation of injury and tissue repair in nonepithelial tissues. The effects of LPA on intestinal epithelial wound repair in vitro and in vivo were characterized.

METHODS

Effects of LPA on intestinal epithelial restitution and proliferation were assessed by using an in vitro wounding model with confluent intestinal epithelial cell line 6 (IEC-6) monolayers and colorimetric thiazolyl blue (MTT) assays. In addition, LPA signaling pathways were characterized. Effects of LPA on intestinal wound healing in vivo were studied by using the trinitrobenzene model of colitis in rats.

RESULTS

LPA significantly enhanced migration and inhibited cell proliferation of IEC-6 cells in vitro. The effects on intestinal epithelial cell migration and proliferation were mediated through transforming growth factor beta (TGF-beta)-independent pathways and binding to a G-protein receptor. In addition, LPA significantly ameliorated intestinal epithelial injury in the trinitrobenzene model of colitis in rats.

CONCLUSIONS

These findings suggest that LPA enhances intestinal epithelial wound healing by modulation of intestinal epithelial cell migration and proliferation through TGF-beta-independent pathways. Thus, exogenous administration of LPA may provide a new approach for modulating intestinal injury in vivo.

[Case report of epithelioid hemangioendothelioma of the frontal region metastatic to the parotid gland]

BACKGROUND

The epithelioid hemangioendothelioma is a soft tissue tumor of vascular origin. Typical localisations are subcutis, cutis, liver, lungs and bones. It has been described in 1982 by Weiss and Enzinger as a separate tumor entity. Due to the unpredictable biological behaviour of the tumor, a borderline malignancy is assumed.

CASE REPORT

We report on the case of a 44-year old woman with a metastasising epithelioid hemangioendothelioma in the head and neck area. The primary tumor was located in the subcutis of the left forehead. Due to local recurrences surgical treatment was performed three times after the initial removal in 1993. At the time of the last local recurrence in 1996, a tumor in the left parotid gland was diagnosed and was the reason for a lateral parotidectomy. Pathohistologically, a metastasis of the epithelioid hemangioendothelioma was found. Postoperative radiotherapy was performed and no recurrence occurred until now (22 months follow-up).

CONCLUSION

Metastatic epithelioid hemangioendotheliomas are rarely found in the head and neck area. Literature has not yet reported on metastasis formation in the parotid gland. The case illustrates the potentially malignant behaviour of epithelioid hemangioendotheliomas. Hence, therapy should consist of a combination of radical tumor removal and post-operative radiotherapy.