Effects of cholesterol on CCK-1 receptors and caveolin-3 proteins recycling in human gallbladder muscle

The contraction of gallbladders (GBs) with cholesterol stones is impaired due to high cholesterol concentrations in caveolae compared with GBs with pigment stones. The reduced contraction is caused by a lower cholecystokinin (CCK)-8 binding to CCK-1 receptors (CCK-1R) due to caveolar sequestration of receptors. We aimed to examine the mechanism of cholesterol-induced sequestration of receptors. Muscle cells from human and guinea pig GBs were studied. Antibodies were used to examine CCK-1R, antigens of early and recycling endosomes, and total (CAV-3) and phosphorylated caveolar-3 protein (pCAV-3) by Western blots. Contraction was measured in muscle cells transfected with CAV3 mRNA or clathrin heavy-chain small-interfering RNA (siRNA). CCK-1R returned back to the bulk plasma membrane (PM) 30 min after CCK-8 recycled by endosomes, peaking at 5 min in early endosomes and at 20 min in recycling endosomes. Pretreatment with cholesterol-rich liposomes inhibited the transfer of CCK-1R and of CAV-3 in the endosomes by blocking CAV-3 phosphorylation. 4-Amino-5-(4-chloro-phenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (inhibitor of tyrosine kinase) reproduced these effects by blocking pCAV-3 formation, increasing CAV-3 and CCK-1R sequestration in the caveolae and impairing CCK-8-induced contraction. CAV-3 siRNA reduced CAV-3 protein expression, decreased CCK-8-induced contraction, and accumulated CCK-1R in the caveolae. Abnormal concentrations of caveolar cholesterol had no effect on met-enkephalin that stimulates a delta-opioid receptor that internalizes through clathrin. We found that impaired muscle contraction in GBs with cholesterol stones is due to high caveolar levels of cholesterol that inhibits pCAV-3 generation. Caveolar cholesterol increases the caveolar sequestration of CAV-3 and CCK-1R caused by their reduced recycling to the PM.

Neoadjuvant bevacizumab, oxaliplatin, 5-fluorouracil, and radiation in clinical stage II-III rectal cancer

4105^

Background: This study evaluates induction bevacizumab and FOLFOX followed by concurrent chemoradiotherapy (CRT) with bevacizumab, weekly oxaliplatin, and continuous infusion 5-FU prior to surgical resection of newly-diagnosed Stage II or III rectal cancer. Methods: Eligible patients received one month of induction, biweekly bevacizumab (5mg/kg) and modified FOLFOX6. Patients then received 50.4Gy of radiation and concurrent bevacizumab (5 mg/kg on days 1, 15, and 29), oxaliplatin (50 mg/m2/week for 6 weeks), and 5-FU (200mg/m2/day) as a continuous IV infusion throughout radiation. Due to gastrointestinal toxicity, the oxaliplatin dose was reduced to 40 mg/m2/week. Resection was performed 4 to 8 weeks after the completion of CRT. Adjuvant chemotherapy was started after 4 but less than 12 weeks following surgical resection and consisted of 6 biweekly treatments of modified FOLFOX6 and bevacizumab. Results: Twenty-six eligible patients were treated. The median age was 50. One patient developed a grade 4 arrhythmia during induction chemotherapy and was removed from the study. Of the remaining 25 patients, there were no other grade 3 or 4 toxicities during induction FOLFOX/bevacizumab. Toxicity was more significant during chemoradiation. Any grade 3 toxicity was experienced by 19 of 25 (76%) patients. Grade 3 toxicities included diarrhea (40%), neutropenia (16%), pain (16%), fatigue (8%), nausea (8%), and radiation dermatitis (8%) and bleeding with menstruation (4%). Grade 4 toxicities included neutropenia (4%), sepsis (4%) and nausea/diarrhea (4%). Six of 25 resected patients (24%) had a complete pathologic response. Eight of 25 patients (32%) developed post-operative wound complications including infection/abscess (n=4), fistula (n=2), ischemic colonic reservoir (n=1) and sterile fluid collection (n=1). Nine of 25 (36%) patients developed postoperative wound complications including infection (n=4), delayed healing (n=3), leak/abscess (n=2), sterile fluid collection (n=2), ischemic colonic reservoir (n=1), and fistula (n=1). Conclusions: Concurrent oxaliplatin, bevacizumab, continuous infusion 5-FU and radiation causes significant gastrointestinal toxicity. The pathologic complete response rate of this regimen to similar to other fluorouracil based chemoradiaton regimens. The high incidence of post-operative wound complications is concerning and consistent with other reports utilizing bevacizumab prior to major surgical resections.

[Table: see text]

ASCO Conflict of Interest Policy and Exceptions

In compliance with the guidelines established by the ASCO Conflict of Interest Policy (J Clin Oncol. 2006 Jan 20;24[3]:519–521) and the Accreditation Council for Continuing Medical Education (ACCME), ASCO strives to promote balance, independence, objectivity, and scientific rigor through disclosure of financial and other interests, and identification and management of potential conflicts. According to the ASCO Conflict of Interest Policy, the following financial and other relationships must be disclosed: employment or leadership position, consultant or advisory role, stock ownership, honoraria, research funding, expert testimony, and other remuneration (J Clin Oncol. 2006 Jan 20;24[3]:520). The ASCO Conflict of Interest Policy disclosure requirements apply to all authors who submit abstracts to the Annual Meeting.

For clinical trials that began accrual on or after April 29, 2004, ASCO's Policy places some restrictions on the financial relationships of principal investigators (J Clin Oncol. 2006 Jan 20;24[3]:521). If a principal investigator holds any restricted relationships, his or her abstract will be ineligible for placement in the 2009 Annual Meeting unless the ASCO Ethics Committee grants an exception. Among the circumstances that might justify an exception are that the principal investigator (1) is a widely acknowledged expert in a particular therapeutic area; (2) is the inventor of a unique technology or treatment being evaluated in the clinical trial; or (3) is involved in international clinical oncology research and has acted consistently with recognized international standards of ethics in the conduct of clinical research. NIH-sponsored trials are exempt from the Policy restrictions. Abstracts for which authors requested and have been granted an exception in accordance with ASCO's Policy are designated with a caret symbol (^) in the Annual Meeting Proceedings.

For more information about the ASCO Conflict of Interest Policy and the exceptions process, please visit www.asco.org/conflictofinterest .

Does sodium hyaluronate- and carboxymethylcellulose-based bioresorbable membrane (Seprafilm) decrease operative time for loop ileostomy closure?

BACKGROUND

Adhesions can result in serious clinical complications and make ileostomy closure, which is relatively simple procedure into a complicated and prolonged one. The use of sodium hyaluronate and carboxymethyl cellulose membrane (Seprafilm) was proven to significantly reduce the postoperative adhesions at the site of application. The aim of this study was to assess the incidence and severity of adhesions around a loop ileostomy and to analyze the length of time and morbidity for mobilization at the time of ileostomy closure with and without the use of Seprafilm.

METHODS

Twenty-nine surgeons from 15 institutions participated in this multicenter prospective randomized study. 191 patients with loop ileostomy construction were randomly assigned to either receive Seprafilm under the midline incision and around the stoma (Group I), only under the midline incision (Group II), or not to receive Seprafilm (Group III). At ileostomy closure, adhesions were quantified and graded; operative morbidity was also measured.

RESULTS

All 3 groups were comparable relative to gender, mean age and number of patients with prior operations (26, 25 and 19, respectively). Group II patients were significantly more likely to have pre-existing adhesions than Group III patients (30.6% vs. 14.1%, p = 0.025). At stoma mobilization, significantly more patients in Group III than in Group I had adhesions around the stoma (95.2% vs. 82.3%, p = 0.021). Mean operative times were 27, 25, and 28 minutes, respectively (p = 0.38), with significant differences among sites. There was no significant difference in the number of patients needing myotomy or enterotomy (29, 27 and 24 patients, respectively), nor in the number of postoperative complications (7, 9 and 7 patients, respectively).

CONCLUSIONS

When consistently applied, Seprafilm significantly decreased adhesion formation around the stoma but not operative times without any increase in the need for myotomy or enterotomy. These findings were not seen in the overall study population possibly due to the large number of surgeons using a variety of application techniques.

Increased expression of keratinocyte growth factor messenger RNA associated with inflammatory bowel disease

BACKGROUND & AIMS

Alterations in intestinal epithelial cell function are common in inflammatory bowel disease (IBD). Keratinocyte growth factor (KGF) is an epithelial cell-specific mitogen. The aim of this study was to examine IBD tissue for altered KGF expression.

METHODS

Expression levels of the KGF and KGF receptor transcripts were analyzed by ribonuclease protection assay. The cellular localization of each transcript was determined using in situ hybridization.

RESULTS

KGF messenger RNA levels were increased in inflamed IBD tissue in comparison with control tissues. In normal tissue, KGF messenger RNA was localized to the mesenchymal cells at the tip of the villi in the small intestine and directly underlying the mature enterocytes in the colon, whereas in IBD it was present throughout the lamina propria, although distinct from the germinal centers. The topographic distribution of the KGF in situ hybridization signal in IBD was similar to that observed for T lymphocytes. In contrast, KGF receptor transcripts were localized to the cryptal region of the mucosal epithelium in both normal and IBD tissue, with no apparent differences in the level of expression.

CONCLUSIONS

The increased expression of KGF in IBD suggests that it may be involved in mediating the altered regulatory functions of intestinal epithelial cells in this disease.