CDKN2A Germline Rare Coding Variants and Risk of Pancreatic Cancer in Minority Populations

Background: Pathogenic germline mutations in the CDKN2A tumor suppressor gene are rare and associated with highly penetrant familial melanoma and pancreatic cancer in non-Hispanic whites (NHW). To date, the prevalence and impact of CDKN2A rare coding variants (RCV) in racial minority groups remain poorly characterized. We examined the role of CDKN2A RCVs on the risk of pancreatic cancer among minority subjects.Methods: We sequenced CDKN2A in 220 African American (AA) pancreatic cancer cases, 900 noncancer AA controls, and 183 Nigerian controls. RCV frequencies were determined for each group and compared with that of 1,537 NHW patients with pancreatic cancer. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for both a case-case comparison of RCV frequencies in AAs versus NHWs, and case-control comparison between AA cases versus noncancer AA controls plus Nigerian controls. Smaller sets of Hispanic and Native American cases and controls also were sequenced.Results: One novel missense RCV and one novel frameshift RCV were found among AA patients: 400G>A and 258_278del. RCV carrier status was associated with increased risk of pancreatic cancer among AA cases (11/220; OR, 3.3; 95% CI, 1.5-7.1; P = 0.004) compared with AA and Nigerian controls (17/1,083). Further, AA cases had higher frequency of RCVs: 5.0% (OR, 13.4; 95% CI, 4.9-36.7; P < 0.001) compared with NHW cases (0.4%).Conclusions: CDKN2A RCVs are more common in AA than in NHW patients with pancreatic cancer and associated with moderately increased pancreatic cancer risk among AAs.Impact: RCVs in CDKN2A are frequent in AAs and are associated with risk for pancreatic cancer. Cancer Epidemiol Biomarkers Prev; 27(11); 1364-70. ©2018 AACR.

Self-Reported Questionnaire Detects Family History of Cancer in a Pancreatic Cancer Screening Program

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer death; approximately 5-10% of PDAC is hereditary. Self-administered health history questionnaires (HHQs) may provide a low-cost method to detail family history (FH) of malignancy. Pancreas Center patients were asked to enroll in a registry; 149 with PDAC completed a HHQ which included FH data. Patients with FH of PDAC, or concern for inherited PDAC syndrome, were separately evaluated in a Prevention Program and additionally met with a genetic counselor (GC) to assess PDAC risk (n = 61). FH obtained through GC and HHQ were compared using Wilcoxon signed-rank sum and generalized linear mixed models with Poisson distribution. Agreement between GC and HHQ risk-assessment was assessed using kappa (κ) statistic. In the Prevention Program, HHQ was as precise in detecting FH of cancer as the GC (all p > 0.05). GC and HHQ demonstrated substantial agreement in risk-stratification of the Prevention Program cohort (κ = 0.73, 95% CI 0.59-0.87.) The sensitivity of the HHQ to detect a patient at elevated risk (i.e., moderate- or high-risk) of PDAC, compared to GC, was 82.9% (95% CI 67.3-92.3%) with a specificity of 95% (95% CI 73.1-99.7%). However, seven patients who were classified as average-risk by the HHQ were found to be at an elevated-risk of PDAC by the GC. In the PDAC cohort, 30/149 (20.1%) reported at least one first-degree relative (FDR) with PDAC. The limited sensitivity of the HHQ to detect patients at elevated risk of PDAC in the Prevention Program cohort suggests that a GC adds value in risk-assessment in this population. The HHQ may offer an opportunity to identify high-risk patients in a PDAC population.

Absence of pancreatic intraepithelial neoplasia predicts poor survival after resection of pancreatic cancer

OBJECTIVES

Pancreatic intraepithelial neoplasia (PanIN), thought to represent the dominant precursor of pancreatic adenocarcinoma (PDAC), is often found synchronously adjacent to resected PDAC tumors. However, its prognostic significance on outcome after PDAC resection is unknown.

METHODS

A total of 342 patients who underwent resection for PDAC between 2005 and 2010 at a single institution were identified and stratified according to highest grade of PanIN demonstrated surrounding the tumor. Clinical and pathologic characteristics of each patient and tissue were recorded and analyzed. The primary outcome was length of survival after resection.

RESULTS

An absence of PanIN lesions was identified in 32 patients (9%), low grade PanIN without synchronous high grade lesions was identified in 52 patients (15%), and high grade PanIN was found in 258 patients (75%). Median survival were 12.8 months for the non-PanIN group, 26.3 months for the low-grade PanIN group, and 23.8 months for the high-grade PanIN groups (P = 0.043). In multivariable analysis, absence of PanIN was independently associated with poor survival (P = 0.002).

CONCLUSIONS

The patients who demonstrate an absence of PanIN in the pancreatic tissue adjacent to the resected PDAC tumor have shorter postresection survival compared with those who demonstrate a PanIN lesion.

Pancreatic ductal adenocarcinoma: Risk factors, screening, and early detection

Pancreatic cancer is the fourth most common cause of cancer-related deaths in the United States, with over 38000 deaths in 2013. The opportunity to detect pancreatic cancer while it is still curable is dependent on our ability to identify and screen high-risk populations before their symptoms arise. Risk factors for developing pancreatic cancer include multiple genetic syndromes as well as modifiable risk factors. Genetic conditions include hereditary breast and ovarian cancer syndrome, Lynch Syndrome, familial adenomatous polyposis, Peutz-Jeghers Syndrome, familial atypical multiple mole melanoma syndrome, hereditary pancreatitis, cystic fibrosis, and ataxia-telangiectasia; having a genetic predisposition can raise the risk of developing pancreatic cancer up to 132-fold over the general population. Modifiable risk factors, which include tobacco exposure, alcohol use, chronic pancreatitis, diet, obesity, diabetes mellitus, as well as certain abdominal surgeries and infections, have also been shown to increase the risk of pancreatic cancer development. Several large-volume centers have initiated such screening protocols, and consensus-based guidelines for screening high-risk groups have recently been published. The focus of this review will be both the genetic and modifiable risk factors implicated in pancreatic cancer, as well as a review of screening strategies and their diagnostic yields.

BRCA1 and BRCA2 germline mutations are frequently demonstrated in both high-risk pancreatic cancer screening and pancreatic cancer cohorts

BACKGROUND

Approximately 10% of pancreatic ductal adenocarcinoma (PDAC) is due to a genetic predisposition, including the breast and ovarian cancer syndrome germline mutations BRCA1 and BRCA2. Knowledge of specific genetic mutations predisposing to PDAC may enable risk stratification, early detection, and the development of effective screening and surveillance programs. In the current study, the authors attempted to determine the diagnostic yield of testing for BRCA1/2 germline mutations in a PDAC screening cohort and a PDAC cohort referred for genetic testing.

METHODS

Patients in a high-risk PDAC prevention and genetics program or those with a personal history of PDAC who were referred for genetic evaluation underwent testing for BRCA1/2 germline mutations. Clinical BRCA1/2 genetic testing included testing for the 3 Ashkenazi Jewish founder mutations or BRCA1/2 comprehensive testing.

RESULTS

A total of 37 patients without PDAC underwent BRCA1/2 testing at the study institution. Genetic testing identified 7 patients who were BRCA1/2 carriers for a yield of 18.9%. Six patients carried Ashkenazi Jewish founder mutations (3 with BRCA1 and 3 with BRCA2), and 1 patient was found to have a BRCA2 mutation on comprehensive testing. Thirty-two patients with PDAC underwent BRCA1/2 genetic testing. Five patients had Ashkenazi Jewish founder mutations (2 with BRCA1 and 3 with BRCA2), and 2 patients were found to have BRCA2 mutations on comprehensive testing. The diagnostic yield was 7 of 32 patients (21.9%).

CONCLUSIONS

BRCA1/2 testing is useful in PDAC risk stratification and alters risk assignment and screening recommendations for mutation-positive patients and their families. Clinical BRCA1/2 testing should be considered in patients of Ashkenazi Jewish descent with a personal history or family history of PDAC, even in the absence of a family history of breast and ovarian cancer.

High prevalence of BRCA1 and BRCA2 germline mutations with loss of heterozygosity in a series of resected pancreatic adenocarcinoma and other neoplastic lesions

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is associated with the breast ovarian cancer syndrome (BRCA1/BRCA2) mutations. It is unknown if this association is causal.

EXPERIMENTAL DESIGN

This is a single-site study of patients who underwent surgical pancreatic tumor resection and self-identified as Ashkenazi Jewish. DNA from normal pancreatic tissue was genotyped for the three Ashkenazi Jewish BRCA1/2 founder mutations BRCA1 185delAG, BRCA1 5382insC, and BRCA2 6174delT, and loss of heterozygosity (LOH) was determined by sequencing DNA from microdissected tumor. When additional tumor tissue was available, p53 immunohistochemistry (IHC) was conducted.

RESULTS

Thirty-seven patients underwent surgery for PDAC, seven for intraductal papillary mucinous neoplasm (IPMN), and 19 for other diseases. A high prevalence of BRCA1/2 mutations was found in the surgical cohort (12/63; 19.0%; P < 0.001), PDAC cohort (8/37; 21.6%; P < 0.001), and IPMN cohort (2/7; 28.6%; P = .01) compared with published control mutation frequency. A high prevalence of BRCA1 185delAG (8.1%; P < 0.001) and BRCA2 6174delT (10.8%; P < 0.001) in Ashkenazi Jewish patients with PDAC was shown. BRCA1/2 LOH was found in 2 of 4 BRCA1-associated PDACs and 3 of 4 BRCA2-associated PDACs. Positive p53 IHC was found in 5 of 8 BRCA1/2 PDACs.

CONCLUSIONS

We show a high prevalence of BRCA1/2 mutations with LOH in an Ashkenazi Jewish cohort of surgically resected PDAC and neoplastic lesions, suggesting that these germline mutations are causal in selected individuals.

Mice that express human interleukin-8 have increased mobilization of immature myeloid cells, which exacerbates inflammation and accelerates colon carcinogenesis

BACKGROUND & AIMS

Interleukin (IL)-8 has an important role in initiating inflammation in humans, attracting immune cells such as neutrophils through their receptors CXCR1 and CXCR2. IL-8 has been proposed to contribute to chronic inflammation and cancer. However, mice do not have the IL-8 gene, so human cancer cell lines and xenograft studies have been used to study the role of IL-8 in colon and gastric carcinogenesis. We generated mice that carry a bacterial artificial chromosome that encompasses the entire human IL-8 gene, including its regulatory elements (IL-8Tg mice).

METHODS

We studied the effects of IL-8 expression in APCmin(+/-) mice and IL-8Tg mice given azoxymethane and dextran sodium sulfate (DSS). We also examined the effects of IL-8 expression in gastric cancer in INS-GAS mice that overexpress gastrin and IL-8Tg mice infected with Helicobacter felis.

RESULTS

In IL-8Tg mice, expression of human IL-8 was controlled by its own regulatory elements, with virtually no messenger RNA or protein detectable under basal conditions. IL-8 was strongly up-regulated on systemic or local inflammatory stimulation, increasing mobilization of immature CD11b(+)Gr-1(+) myeloid cells (IMCs) with thioglycolate-induced peritonitis, DSS-induced colitis, and H. felis-induced gastritis. IL-8 was increased in colorectal tumors from patients and IL-8Tg mice compared with nontumor tissues. IL-8Tg mice developed more tumors than wild-type mice following administration of azoxymethane and DSS. Expression of IL-8 increased tumorigenesis in APCmin(+/-) mice compared with APCmin(+/-) mice that lack IL-8; this was associated with increased numbers of IMCs and angiogenesis in the tumors.

CONCLUSIONS

IL-8 contributes to gastrointestinal carcinogenesis by mobilizing IMCs and might be a therapeutic target for gastrointestinal cancers.

Incidence of subsequent pancreatic adenocarcinoma in patients with a history of nonpancreatic primary cancers

BACKGROUND

Several environmental risk factors are known to predispose individuals to pancreatic cancer, and up to 15% of pancreatic cancers have an inherited component. Understanding metachronous cancer associations can modify pancreas cancer risk. The objective of this study was to investigate the association of nonpancreatic cancers with subsequent pancreatic adenocarcinoma.

METHODS

The authors used data from the US Surveillance, Epidemiology, and End Results (SEER) registries to identify 1,618,834 individuals who had a primary malignancy and subsequent pancreatic adenocarcinoma (n = 4013). Standardized incidence ratios were calculated as an approximation of relative risk (RR) for the occurrence of pancreatic adenocarcinoma after another primary malignancy.

RESULTS

Among patients who were diagnosed with a first primary malignancy at ages 20 to 49 years, the risk of subsequent pancreatic adenocarcinoma was increased among patients who had cancers of the ascending colon (relative risk [RR], 4.62; 95% confidence interval [CI], 1.86-9.52), hepatic flexure (RR, 5.42; 95% CI, 1.12-15.84), biliary system (RR, 13.14; 95% CI, 4.27-30.66), breast (RR, 1.32; 95% CI, 1.09-1.59), uterine cervix (RR, 1.61; 95% CI, 1.02-2.41), testes (RR, 2.78; 95% CI, 1.83-4.05), and hematopoietic system (RR, 1.83; 95% CI, 1.28-2.53). Among patients who had a first malignancy at ages 50 to 64 years, the risk was increased after cancers of the stomach (RR, 1.88; 95% CI, 1.13-2.93), hepatic flexure (RR, 2.25; 95% CI, 1.08-4.13), lung and bronchus (RR, 1.46; 95% CI, 1.16-1.82), pharynx (RR, 2.26; 95% CI, 1.13-4.04), and bladder (RR, 1.24; 95% CI, 1.03-1.48). Among patients who had a primary cancer after age 65 years, the risk was increased after cancers of the stomach (RR, 1.79; 95% CI, 1.23-2.53), hepatic flexure (RR, 1.76; 95% CI, 1.06-2.75), biliary system (RR, 2.35; 95% CI, 1.17-4.20), and uterus (RR, 1.23; 95% CI, 1.03-1.47).

CONCLUSIONS

The results from the current population-based data set suggested that pancreatic adenocarcinoma is associated with certain primary cancers. Genetic predisposition and common environmental and behavioral risk factors all may contribute to this observation. Specific tumor associations will guide future risk-stratification efforts.

Physician knowledge and appropriate utilization of computed tomographic colonography in colorectal cancer screening

GOALS

To assess physician understanding of computed tomographic colonography (CTC) in colorectal cancer (CRC) screening guidelines in a pilot study.

BACKGROUND

CTC is a sensitive and specific method of detecting colorectal polyps and cancer. However, several factors have limited its clinical availability, and CRC screening guidelines have issued conflicting recommendations.

STUDY

A web-based survey was administered to physicians at two institutions with and without routine CTC availability.

RESULTS

398 of 1655 (24%) participants completed the survey, 59% was from the institution with routine CTC availability, 52% self-identified as trainees, and 15% as gastroenterologists. 78% had no personal experience with CTC. Only 12% was aware of any current CRC screening guidelines that included CTC. In a multiple regression model, gastroenterologists had greater odds of being aware of guidelines (OR 3.49, CI 1.67-7.26), as did physicians with prior CTC experience (OR 4.81, CI 2.39-9.68), controlling for institution, level of training, sex, and practice type. Based on guidelines that recommend CTC, when given a clinical scenario, 96% of physicians was unable to select the appropriate follow-up after a CTC, which was unaffected by institution.

CONCLUSIONS

Most physicians have limited experience with CTC and are unaware of recent recommendations concerning CTC in CRC screening.

Pancreatic cancer screening in a prospective cohort of high-risk patients: a comprehensive strategy of imaging and genetics

PURPOSE

Pancreatic cancer is a virtually uniformly fatal disease. We aimed to determine if screening to identify curable neoplasms is effective when offered to patients at high risk.

EXPERIMENTAL DESIGN

Patients at high risk of pancreatic cancer were prospectively enrolled into a screening program. Endoscopic ultrasound (EUS), magnetic resonance imaging (MRI), and genetic testing were offered by a multidisciplinary team according to each patient's risk.

RESULTS

Fifty-one patients in 43 families were enrolled, with mean age of 52 years, 35% of whom were male. Of these patients, 31 underwent EUS and 33 MRI. EUS revealed two patients with pancreatic cancer (one resectable, one metastatic), five with intraductal papillary mucinous neoplasms (IPMN), seven with cysts, and six with parenchymal changes. Five had pancreatic surgery (one total pancreatectomy for pancreatic cancer, three distal and one central pancreatectomy for pancreatic intraepithelial neoplasia 2 and IPMN). A total of 24 (47%) had genetic testing (19 for BRCA1/2 mutations, 4 for CDKN2A, 1 for MLH1/MSH2) and 7 were positive for BRCA1/2 mutations. Four extrapancreatic neoplasms were found: two ovarian cancers on prophylactic total abdominal hysterectomy and bilateral salpingo-oophorectomy, one carcinoid, and one papillary thyroid carcinoma. Overall, 6 (12%) of the 51 patients had neoplastic lesions in the pancreas and 9 (18%) had neoplasms in any location. All were on the initial round of screening. All patients remain alive and without complications of screening.

CONCLUSIONS

Pancreatic cancer screening for high-risk patients with a comprehensive strategy of imaging and genetics is effective and identifies curable neoplasms that can be resected. Ongoing study will better define who will benefit from screening and what screening strategy will be the most effective.

Head and neck squamous cell carcinoma in FAMMM syndrome

BACKGROUND

Germline mutations at the INK4a/p16 locus are implicated in several human cancer syndromes, including familial atypical multiple mole melanoma (FAMMM) syndrome, FAMMM-pancreatic cancer (FAMMM-PC) syndrome, and in familial head and neck cancer syndrome.

METHODS

We present an individual with a family history of melanoma and pancreatic cancer who had multiple dysplastic nevi, squamous cell carcinoma of the tongue at age 22, multiple melanomas, a second squamous cell cancer of the tongue at age 40, and ultimately a pancreatic cancer.

RESULTS

We demonstrate a germline mutation in INK4a and loss of heterozygosity at this locus in his HNSCC tissue.

CONCLUSIONS

This report suggests that INK4a germline mutations associated with FAMMM/FAMMM-PC can also be associated with HNSCC. We conclude that HNSCC in young individuals should prompt clinicians to obtain a family history and consider that the patient may have a germline p16 defect that could predispose them to other cancers, including melanoma and pancreatic cancer.

Costs and cost effectiveness of a health care provider-directed intervention to promote colorectal cancer screening

PURPOSE

Colorectal cancer (CRC) screening remains underutilized in the United States. Prior studies reporting the cost effectiveness of randomized interventions to improve CRC screening have not been replicated in the setting of small physician practices. We recently conducted a randomized trial evaluating an academic detailing intervention in 264 small practices in geographically diverse New York City communities. The objective of this secondary analysis is to assess the cost effectiveness of this intervention.

METHODS

A total of 264 physician offices were randomly assigned to usual care or to a series of visits from trained physician educators. CRC screening rates were measured at baseline and 12 months. The intervention costs were measured and the incremental cost-effectiveness ratio (ICER) was derived. Sensitivity analyses were based on varying cost and effectiveness estimates.

RESULTS

Academic detailing was associated with a 7% increase in CRC screening with colonoscopy. The total intervention cost was $147,865, and the ICER was $21,124 per percentage point increase in CRC screening rate. Sensitivity analyses that varied the costs of the intervention and the average medical practice size were associated with ICERs ranging from $13,631 to $36,109 per percentage point increase in CRC screening rates.

CONCLUSION

A comprehensive, multicomponent academic detailing intervention conducted in small practices in metropolitan New York was clinically effective in improving CRC screening rates, but was not cost effective.

Cost-effectiveness of a health care provider-directed intervention to promote colorectal cancer screening

6583

Background: Colorectal cancer (CRC) screening remains underutilized. Prior studies reported the cost-effectiveness of interventions to improve CRC screening, but none have been replicated in the setting of small medical practices. We recently conducted a randomized trial of an academic detailing strategy within 264 small physician offices in New York City. The objective of this analysis is to assess the cost-effectiveness of this intervention. Methods: 264 physician offices were randomized to usual care or to a series of ‘academic detailing’ visits from health educators trained in evidence-based CRC screening guidelines. CRC screening rates were measured at baseline and 12 months. Intervention-related costs were categorized as fixed or intervention delivery costs. The incremental cost effectiveness ratio (ICER) was expressed as cost per percentage point increase in CRC screening. Each practice contained an average of 4 physicians. Sensitivity analyses were estimated by varying the number of physicians per practice and accordingly, intervention delivery costs. Results: Academic detailing resulted in a 7% increase in CRC screening with colonoscopy. The cost of the intervention was $147,865. The ICER was $21,124 per percentage point increase in CRC screening. Sensitivity analyses that varied the intervention delivery costs by the average medical practice size were associated with ICERs ranging from $13,361 (8 physicians/office) to $36,109 (2 physicians/office) per percentage point increase in CRC screening rates. Conclusions: A multi-component academic detailing intervention conducted in small urban practices was clinically effective, but was not cost-effective when compared to other reported low-intensity patient-directed and infrastructural interventions ($131-$1,161 per percentage increase in CRC screening). (Table) While academic detailing may be more cost-effective in physician practices of larger size, new cost-effective approaches in small community practices are needed.

[Table: see text]

No significant financial relationships to disclose.

Head and neck squamous cell cancer as part of the germline p16/INK4a mutation-induced FAMMM syndrome

6052

Background: p16/INK4a constitutes an important cancer susceptibility locus. Germline mutations at this locus have been implicated in several human cancer syndromes, including familial atypical multiple mole melanoma (FAMMM) syndrome, FAMMM-pancreatic cancer (FAMMM-PC) syndrome, and more recently, in familial head and neck cancer syndrome. Methods: We present an individual with a family history of both pancreatic cancer and melanoma, who developed squamous cell carcinoma of the tongue at 21 years old, multiple melanomas, a second squamous cell cancer of the tongue at 40 years old, and ultimately a pancreatic cancer. Results: We identify a germline mutation in INK4a that leads to a substitution of tryptophan for glycine in the Ankyrin III domain of the p16 protein (G101W). We demonstrate loss of heterozygosity at the INK4a locus and lack of p16 expression in the second head and neck squamous cell cancer (HNSCC) tissue. Based on these and on previously published data, we propose that HNSCC resulting from an INK4a germline mutation is a variant of the FAMMM/FAMMM-PC syndrome. Further studies will determine whether there is genotype-phenotype correlation between these syndrome variants. Conclusions: We conclude that young individuals who develop HNSCC should be considered at high-risk for other cancers, including pancreatic cancer and melanoma. They should be advised to avoid cigarette smoking and should be considered for pancreas cancer screening.

No significant financial relationships to disclose.

BRAF and KRAS gene mutations in intraductal papillary mucinous neoplasm/carcinoma (IPMN/IPMC) of the pancreas

The Raf/MEK/ERK (MAPK) signal transduction is an important mediator of a number of cellular fates including growth, proliferation, and survival. The BRAF gene is activated by oncogenic RAS, leading to cooperative effects in cells responding to growth factor signals. Our study was performed to elucidate a possible role of BRAF in the development of IPMN (Intraductal Papillary Mucinous Neoplasm) and IPMC (Intraductal Papillary Mucinous Carcinoma) of the pancreas. Mutations of BRAF and KRAS were evaluated in 36 IPMN/IPMC samples and two mucinous cystadenomas by direct genomic sequencing. Exons 1 for KRAS, and 5, 11, and 15 for BRAF were examined. Totally we identified 17 (47%) KRAS mutations in exon 1, codon 12 and one missense mutation (2.7%) within exon 15 of BRAF. The mutations appear to be somatic since the same alterations were not detected in the corresponding normal tissues. Our data provide evidence that oncogenic properties of BRAF contribute to the tumorigenesis of IPMN/IPMC, but at a lower frequency than KRAS.

Advances in the Genetic Screening, Work-up, and Treatment of Pancreatic Cancer

Familiarity with the updated results in genetic screening and work-up presented here is essential to early diagnosis and possible cure. In the metastatic setting, we most frequently begin with the GTX regimen, consisting of Gemcitabine, Taxotere, and Xeloda. The regimen is based on our laboratory data demonstrating a synergistic increase in cell killing of pancreatic cancer cell lines. The combination takes advantage of the selective cell cycle effects of each of the three drugs. In our initial experience, we have seen a response rate of 40% at metastatic sites and 31% at the primary site after nine cycles of GTX. We are now conducting a formal phase II protocol to confirm these results. The median survival of this group of patients (at least 10.4 months) is as long as, or longer than other currently used regimens. In those patients who do not tolerate GTX or progress despite the regimen, we have found that a regimen of the same three drugs, administered on a different schedule, can produce responses. In the neoadjuvant (unresectable) setting, we treat with GTX initially and then follow with radiation; gemcitabine is used as a radiosensitizer during this treatment. An aggressive surgical approach with a team of surgeons were able to resect for cure 12 of the 16 patients who were initially unresectable; one year survival of these 12 was 100%; 2 year survival was 50%. Future work in this disease should focus on targeted agents such as bevacizumab.

Survival following intensive preoperative combined modality therapy with paclitaxel, cisplatin, 5-fluorouracil, and radiation in resectable esophageal carcinoma: A phase I report

PURPOSE

To assess the benefits of aggressive chemoradiation therapy followed by surgery in resectable esophageal carcinoma.

METHOD

Twenty-nine patients with resectable carcinoma were treated with 60 Gy of radiation (2 Gy daily for 6 weeks) and concurrent chemotherapy consisting of continuous infusion of 5-fluorouracil (200-225 mg/m(2)/d), paclitaxel (25, 40, 50, or 60 mg/m(2)) weekly over 1 hour, and cisplatin (25 mg/m(2)) weekly immediately following paclitaxel throughout radiation. Patients received either 4 cycles of postoperative paclitaxel 175 mg/m(2) over 3 hours and cisplatin 75 mg/m(2) every 3 weeks or paclitaxel 175 mg/m(2) over 3 hours and cisplatin 75 mg/m(2) every 3 weeks prior to the initiation of chemoradiation. After induction therapy and restaging, esophagectomy was performed 4 to 6 weeks later.

RESULTS

Twenty-seven patients were eligible for study (26 men, 23 with adenocarcinoma). Median age was 58 years (range 30-73). The maximum tolerated dose combination was paclitaxel 50 mg/m(2) over 1 hour weekly, cisplatin 25 mg/m(2) over 1 hour weekly, 5-fluorouracil 200 mg/m(2)/d by continuous infusion throughout radiotherapy and radiation to 60 Gy. Twenty-two patients completed therapy and underwent surgical resection. Four patients had complete pathological responses and 18 had partial responses with no mortality. The commonest dose-limiting toxicity was mucositis and esophagitis (n = 7). Median follow-up of 27 patients was 150 weeks (range 7-303). At 2-year follow-up 16/27 (59%) were alive and 15/27 (56%) were free of disease. At 4-year follow-up 12/27 (44%) were alive and free of disease. Median follow-up of 22 patients undergoing esophagectomy was 205 weeks (range 26-303). At 4-year follow-up 10/22 (45%) were alive and free of disease. For the 18 patients treated at or above the maximum tolerated dose, median follow-up was 151 weeks (range 35-206) and at 3-year follow-up 9/18 (50%) were alive and free of disease.

CONCLUSION

Aggressive combined modality therapy of esophageal carcinoma was associated with excellent long-term survival in this phase I trial.

Hepatitis B virus reactivation after kidney transplantation and new onset lymphoma

A case of hepatitis B virus (HBV) reactivation after kidney transplantation is reported. The presence of antibodies against hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg) before transplantation indicated previous infection with HBV. Eight years after transplantation, a diffuse, large B-cell lymphoma occurred, and the patient was positive for HBsAg and hepatitis B e antigen, in association with normal activity of serum aminotransferases. Postmortem liver histology did not show any sign of portal tract or lobular inflammation despite the presence at immunostaining of extensive intranuclear and cytoplasmic positivity for HBcAg, indicating active viral replication. Natural immunity to HBV may not protect against reactivation in patients with a suppressed immune system. In this setting, periodic follow-up of HBV serology in patients at highest risk for HBV reactivation to allow for early diagnosis and prompt treatment with lamivudine is highly recommended.

Risk of perforation after colonoscopy and sigmoidoscopy: a population-based study

BACKGROUND

Although the risk of bowel perforation is often cited as a major factor in the choice between colonoscopy and sigmoidoscopy for colorectal screening, good estimates of the absolute and relative risks of perforation are lacking.

METHODS

We used a large population-based cohort that consisted of a random sample of 5% of Medicare beneficiaries living in regions of the United States covered by the Surveillance, Epidemiology, and End Results (SEER) Program registries to determine rates of perforation in people aged 65 years and older. We identified individuals who were cancer-free and had undergone colonoscopy or sigmoidoscopy between 1991 and 1998, calculated both the incidence and risk of perforation within 7 days of the procedure, and explored the impact on incidence and risk of perforation of age, race/ethnicity, sex, comorbidities, and indication for the procedure. We also estimated the risk of death after perforation. Risks were calculated with odds ratios (ORs) and 95% confidence intervals (CIs). All statistical tests were two-sided.

RESULTS

There were 77 perforations after 39 286 colonoscopies (incidence = 1.96/1000 procedures) and 31 perforations after 35 298 sigmoidoscopies (incidence = 0.88/1000 procedures). After adjustment, the OR for perforation from colonoscopy relative to perforation from sigmoidoscopy was 1.8 (95% CI = 1.2 to 2.8). Risk of perforation from either procedure increased in association with increasing age (P(trend)<.001 for both procedures) and the presence of two or more comorbidities (P(trend)<.001 for colonoscopy and P(trend) =.03 for sigmoidoscopy). Compared with those who were endoscopied and did not have a perforation, the risk of death was statistically significantly increased for those who had a perforation after either colonoscopy (OR = 9.0, 95% CI = 3.0 to 27.3) or sigmoidoscopy (OR = 8.8, 95% CI = 1.6 to 48.5). The risk of perforation after colonoscopy, especially for screening procedures, declined during the 8-year study period.

CONCLUSIONS

The risk of perforation after colonoscopy is approximately double that after sigmoidoscopy, but this difference appears to be decreasing. These observations should be useful to clinicians making screening and diagnostic decisions for individual patients and to policy officials setting guidelines for colorectal cancer screening programs.

Functional interaction of lithocholic acid conjugates with M3 muscarinic receptors on a human colon cancer cell line

Lithocholic acid (LA) conjugates interact with M3 receptors, the muscarinic receptor subtype that modulates colon cancer cell proliferation. This observation prompted us to examine the action of bile acids on two human colon cancer cell lines: H508, which expresses M3 receptors, and SNU-C4, which does not. Cellular proliferation was determined using a colorimetric assay. Interaction with muscarinic receptors was determined by measuring inhibition of muscarinic radioligand binding and changes in cellular inositol phosphate (IP) formation. Lithocholyltaurine (LCT) caused a dose-dependent increase in H508 cell proliferation that was not observed in SNU-C4 cells. After a 6-day incubation with 300 microM LCT, H508 cell proliferation increased by 200% compared to control. Moreover, in H508 cells, LCT caused a dose-dependent inhibition of radioligand binding and an increase in IP formation. LCT did not alter the rate of apoptosis in H508 or SNU-C4 cells. These data indicate that, at concentrations achievable in the gut, LA derivatives interact with M3 muscarinic receptors on H508 human colon cancer cells, thereby causing an increase in IP formation and cell proliferation. This suggests a mechanism whereby alterations in intestinal bile acids may affect the growth of colon cancer cells.

The genetics of colorectal cancer

Colon cancer is a common disease that can be sporadic, familial, or inherited. Recent advances have contributed to the understanding of the molecular basis of these various patterns of colon cancer. Germline genetic mutations are the basis of inherited colon cancer syndromes; an accumulation of somatic mutations in a cell is the basis of sporadic colon cancer; and, in Ashkenazi Jewish persons, a mutation that was previously thought to be a polymorphism may cause familial colon cancer. Mutations of three different classes of genes have been described in colon cancer etiology: oncogenes, suppressor genes, and mismatch repair genes. Knowledge of many of the specific mutations responsible for colon carcinogenesis allows an understanding of the phenotypic manifestations observed and forms the basis of genetic testing for inherited disease. Although genetic testing is possible and available, it is only an adjunct to the clinical management of persons at risk for colon cancer and patients with colon cancer. As a result of advances in the understanding of the molecular causes of colon cancer and the availability of colon cancer screening methods such as colonoscopy, it should be possible to prevent the vast majority of colon cancer in our society. Practicing clinicians should recognize the patterns of clinical colon cancer, understand its causes, and be able to use genetic testing and endoscopic screening for prevention.

Chronic dosing of oltipraz in people at increased risk for colorectal cancer

The dithiolethione oltipraz is being developed as a chemopreventive agent for many malignancies, including colorectal cancer, on the basis of its in vivo protective activity against chemically induced tumors in a variety of animal models. This protection has been associated with an enhanced capacity to detoxify reactive carcinogens and, more recently, with increased DNA repair. In a previous single-dose study, elevated detoxification gene expression was observed in the days after oltipraz dosing. Now, in this clinical study, we evaluated the effects of oltipraz when given over a 3-month period. Fourteen individuals with increased risk for colorectal cancer were randomly assigned to one of two oral doses (125 or 250 mg/m2) of oltipraz twice weekly for 12 weeks. Two of seven subjects at the 250 mg/m2 dosage required dose reductions, owing to significant fatigue. The 125 mg/m2 dose level was well tolerated by all patients. Blood or colon tissue (or both) for evaluation of glutathione, glutathione S-transferase, DT-diaphorase activity, and DT-diaphorase mRNA expression were obtained prior to treatment and at weeks 6, 12, and 16. No significant modulation of phase II detoxification enzymes was seen at either dose studied during this period. Phase II trials evaluating a tolerable regimen of oltipraz (as demonstrated in this study) and other possible mechanisms that may be responsible for the protective activity of oltipraz should be pursued.

Activation of the PPAR pathway induces apoptosis and COX-2 inhibition in HT-29 human colon cancer cells

The gamma isoform of the peroxisome proliferator-activated receptor (PPARgamma) is a nuclear receptor that regulates adipocyte differentiation. Recently it has been shown to be expressed in human colonic mucosa and cancer, but its role in colon carcinogenesis and progression is still unclear. We demonstrate that activation of PPARgamma by ciglitazone (cig), a selective PPARgamma ligand, induces HT-29 human colon cancer cells to undergo apoptosis. Treatment with cig also down-regulates expression of cyclooxygenase-2 (COX-2) protein. Simultaneous exposure of cells to cig and 9-cis-retinoic acid (9-cis-RA), a ligand for retinoid X receptor, results in an increased apoptotic effect and increased inhibition of COX-2 expression, compared with cells treated with either cig or 9-cis-RA alone. As COX-2 is overexpressed in human colon cancer and has been implicated in augmenting invasiveness and tumorigenecity, the ability of PPARgamma activation to decrease COX-2 expression and induce apoptosis suggests that the PPARgamma pathway may be considered as a therapeutic target for colon cancer.

Cholinergic receptor up-regulates COX-2 expression and prostaglandin E(2) production in colon cancer cells

The M(3) muscarinic cholinergic receptor has important physiological functions on normal colonic cells. It is frequently expressed on human colon cancer cells and is biologically active. Although it is mitogenic in certain cell models, the importance of this receptor on colon carcinogenesis is unknown. In the present study we have determined expression of the M(3) receptor on human colon cancer tissue compared with matched normal tissue and examined the downstream effect of receptor activation in the HT-29 human colon carcinoma cell line. Using reverse transcription-PCR, M(3) receptor RNA expression was detected in all matched colon carcinoma and normal specimens from eight patients. Five of the eight (62%) patients showed an up to 8-fold greater level of M(3) receptor expression in cancer compared with the matched normal tissue. Exposure of HT-29 cells to carbachol, a stable receptor agonist, results in a 10-fold increase in cyclooxygenase-2 (COX-2) protein. This induction of COX-2 protein was dose dependent and was inhibited by the cholinergic receptor antagonist N-methylscopolamine (NMS). Carbachol caused a dose-dependent increase in prostaglandin E(2) (PGE(2)), the main product of cyclooxygenase activity. The maximum stimulatory effect (40-fold increase) was noted with 1mM carbachol. The increase in PGE(2) was completely abolished by NMS and by the COX-2 selective inhibitor NS398. This suggests that the M(3) receptor mediates PGE(2) production by a mechanism involving COX-2. As COX-2 and PGE(2) are known promoters of gastrointestinal cancer, these data suggest that M(3) receptor activation may facilitate progression of colon carcinoma, in part by a COX-2-mediated cellular mechanism.

Human colon cancer cell proliferation mediated by the M3 muscarinic cholinergic receptor

We have demonstrated previously cell surface receptors for gastrointestinal peptides on 10 human colon cancer cell lines. Because most of the cells studied bind muscarinic cholinergic agonists, we undertook the determination of the cholinergic receptor subtype expressed by human colon cancer cells, as well as the biological function of these receptors, and more specifically, the effect on cell proliferation. We used radiolabeled ligand binding, PCR, calcium mobilization, and cellular proliferation studies. The present study demonstrates a muscarinic cholinergic receptor having two classes of binding site for carbamylcholine. Analysis demonstrated 2499+/-153 binding sites/cell, of which 75% had a high affinity for carbamylcholine (Kd 55 microM), and 25% had a low affinity (Kd 0.33 mM). N-Methylscopolamine, a receptor antagonist, recognized only one binding site having high affinity (Kd 0.20 nM). The number of muscarinic cholinergic binding sites/cell found on colon cancer cells is 50% of the number of receptors found on guinea pig chief cells in physiological conditions. Specific cholinergic receptor antagonists inhibit binding in the following order of potency: N-methylscopolamine > 4-DAMP >> pirenzipine > AF-DX116. This order of potency pharmacologically classifies the receptor as an M3 subtype. Receptor expression, studied by reverse transcription-PCR, correlates with the binding data. Specifically, cell lines that exhibit binding, abundantly expressed the M3 receptor subtype, whereas cell lines that do not exhibit binding for muscarinic cholinergic agonists did not abundantly express the M3 receptor. Agonist activation of the M3 receptor on these cells resulted in intracellular calcium mobilization. The dose-response curve of calcium mobilization suggests that there are spare receptors on these cells. Signal transduction can be inhibited by receptor antagonists in the same order of potency in which the binding is inhibited. Exogenous agonist added to the cells in culture induces significant cell proliferation. These results demonstrate a muscarinic cholinergic receptor of the M3 subtype on human colon cancer cells. This receptor induces intracellular calcium mobilization and mediates cell proliferation. The data suggest that there are spare receptors present, and that there may be enhanced intracellular signal activation in response to receptor binding.

Preclinical and clinical evaluation of broccoli supplements as inducers of glutathione S-transferase activity

Previous studies suggest that cruciferous vegetables may provide protection against carcinogen exposure by inducing detoxification enzymes. ICR(Ha) mice were gavaged with broccoli tablets (1 g/kg), and colon tissues were collected after treatment. Glutathione S-transferase (GST) activity was assayed and peaked on days 1 and 2 after treatment, respectively (P = 0.03). Elevations in GST activity were attributed to the increased expression of mu and pi. These data supported a clinical assessment of broccoli supplements. Twenty-nine subjects at increased risk for colorectal cancer were randomized to group 1 (no cruciferous vegetables) or group 2 (broccoli supplements, 3 g/day) for 14 days. Blood samples and colon biopsies were obtained pre- and postintervention. No significant difference was observed between the GST activities of the control and broccoli supplementation groups posttreatment. Mean lymphocyte GST activity was 107% of baseline in the broccoli supplementation group (range, 79-158%) and 102% of baseline in the control group (range, 75-158 percent;). Correlation of the GST activities of blood lymphocytes and colon mucosa taken simultaneously suggested that the GST activity of blood lymphocytes may be used as a biomarker of the responsiveness of colon tissue to chemopreventive regimens. Future clinical studies evaluating cruciferous vegetables should consider using concentrated dietary supplements in subjects with a previous history of colorectal cancer.

Modulation of gene expression in subjects at risk for colorectal cancer by the chemopreventive dithiolethione oltipraz

Prolonged exposure to mutagenic substances is strongly associated with an individual's risk of developing colorectal cancer. Clinical investigation of oltipraz as a chemopreventive agent is supported by its induction of the expression of detoxication enzymes in various tissues, and its protective activity against the formation of chemically induced colorectal tumors in animals. The goals of the present study were: to determine if oltipraz could induce detoxicating gene expression in human tissues; to identify effective non-toxic doses for more extensive clinical testing; and to establish a relationship between effects in the colon mucosa and those in a more readily available tissue, the peripheral mononuclear cell. 24 evaluable patients at high risk for colorectal cancer were treated in a dose-finding study with oltipraz 125, 250, 500, or 1,000 mg/m2 as a single oral dose. Biochemical analysis of sequential blood samples and colon mucosal biopsies revealed increases in glutathione transferase activity at the lower dose levels. These effects were not observed at the higher doses. More pronounced changes were observed in detoxicating enzyme gene expression in both tissues at all doses. Peripheral mononuclear cell and colon mRNA content for gamma-glutamylcysteine synthetase (gamma-GCS) and DT-diaphorase increased after dosing to reach a peak on day 2-4 after treatment, and declined to baseline in the subsequent 7-10 d. The extent of induction of gene expression in colon mucosa reached a peak of 5.75-fold for gamma-GCS, and a peak of 4.14-fold for DT-diaphorase at 250 mg/m2 ; higher doses were not more effective. Levels of gamma-GCS and DT-diaphorase correlated closely (P < or = 0.001) between peripheral mononuclear cells and colon mucosa both at baseline and at peak. These findings demonstrate that the administration of minimally toxic agents at low doses may modulate the expression of detoxicating genes in the tissues of individuals at high risk for cancer. Furthermore, peripheral mononuclear cells may be used as a noninvasive surrogate endpoint biomarker for the transcriptional response of normal colon mucosa to drug administration.

Glutathione S-transferase activity and glutathione S-transferase mu expression in subjects with risk for colorectal cancer

The glutathione S-transferases (alpha, mu, and pi), a family of Phase II detoxication enzymes, play a critical role in protecting the colon mucosa by catalyzing the conjugation of dietary carcinogens with glutathione. We investigated the efficacy of using the glutathione S-transferase (GST) activity of blood lymphocytes and GST-mu expression as biomarkers of risk for colorectal cancer. GST activity was measured in the blood lymphocytes of control individuals (n = 67) and in the blood lymphocytes (n = 60) and colon tissue (n = 34) of individuals at increased risk for colon cancer. Total GST activity was determined spectrophotometrically with the use of 1-chloro-2,4-dinitrobenzene as a substrate. The ability to express the um subclass of GST was determined with the use of an ELISA. Although interindividual variability in the GST activity of blood lymphocytes was greater than 8-fold (range, 16.7-146.8 nmol/min/mg), the GST activity of blood lymphocytes and colon tissue within an individual was constant over time and was unrelated to sex, age, or race. The GST activity of blood lymphocytes from high-risk individuals was significantly lower than that of blood lymphocytes from control individuals (P < or = 0.004). No association was observed between the frequency of GST-mu phenotype and risk for colorectal cancer. Blood lymphocytes from high-risk individuals unable to express GST-mu had lower levels of GST activity than did those from control subjects with the GST-mu null phenotype; however, this difference was significant in male subjects only (P < or = 0.006). Analysis of paired samples of blood lymphocytes and colon tissue indicated a strong correlation between the GST activity of the two tissue types (Spearman's rank correlation, r = 0.87; P < or = 0.0001). The GST activity of blood lymphocytes may be used to identify high-risk individuals with decreased protection from this Phase II detoxication enzyme who may benefit from clinical trials evaluating GST modulators as chemopreventive agents for colorectal cancer. The GST activity of blood lymphocytes may also be used in colorectal cancer chemoprevention trials to monitor the responsiveness of colon tissue to regimens that modify Phase II detoxication enzymes.

Clinical, pharmacokinetic and biological studies of topotecan

The topoisomerase I inhibitor topotecan is a potent water-soluble camptothecin derivative with activity in a wide variety of preclinical models. Topotecan exhibits schedule dependency in vivo, with the greatest activity being observed on repeated dose schedules. On the basis of the initial clinical studies that showed a short plasma half-life, we attempted to prolong drug exposure by giving topotecan as a 24-h infusion weekly. In a phase I trial, we treated 32 patients at doses ranging from 1.0 to 2.0 mg/m2. The patient population had not been heavily pretreated with chemotherapy and was of good performance status. The incidence of neutropenia, which was dose-limiting, increased sharply with relatively small increments in dose. Doses greater than 1.5 mg/m2 were associated with nadirs that developed after one to three weekly treatments. A patient with metastatic colorectal cancer had a prolonged partial response. The plasma pharmacokinetics of topotecan (lactone and open forms) was characterized in 21 patients. Mean plasma steady-state drug levels were proportional to the dose and were within the range required to exert cytotoxicity in preclinical models. Plasma elimination curves were fit to a one-compartment model, in which the harmonic mean half-life of topotecan was 3.5 h. The ratio of the lactone to the total drug concentrations was constant throughout, which suggests that for this schedule the total drug concentration may be used as a measure of active lactone exposure. This conclusion is supported by the pharmacodynamic analysis, which revealed a positive correlation of both lactone and total drug steady-state concentrations with bone marrow toxicity. The further investigation of this and other infusional schedules in phase II trials will be conducted. The steady-state concentrations of total drug will be measured in several of these trials to establish its potential role in adaptive dosing using this schedule. Such a strategy is justified by the interpatient variability in toxicity and the steep dose-response curve observed in this study. Preliminary evidence of interpatient variability in the mRNA expression of topoisomerase I in the peripheral mononuclear cells and colon mucosa is presented. Trials are under way using biological endpoints for further selection of patients in whom the use of topoisomerase inhibitors may be therapeutically beneficial.

Characterization of bombesin receptors using a novel, potent, radiolabeled antagonist that distinguishes bombesin receptor subtypes

Bombesin (Bn)-related peptides affect numerous cell functions; however, receptor characterization by radiolabeled ligands is limited because only radiolabeled agonists exist. In the present study we demonstrate that [D-Tyr6]Bn(6-13)methyl ester [[D-Tyr6]Bn(6-13)ME] functions as a Bn receptor antagonist with high affinity. The binding of both the radiolabeled agonist 125I-[Tyr4]Bn and the radiolabeled antagonist 125I-[D-Tyr6]Bn(6-13)ME to AR42J cells, murine 3T3 cells, and dispersed guinea pig pancreatic acini was time and temperature dependent, saturable, and reversible. Binding of the antagonist more rapidly reached equilibrium and was more rapidly reversible. Guanine nucleotides did not affect binding of the radiolabeled antagonist, whereas guanosine-5'-(beta,gamma-imido)triphosphate decreased agonist binding by decreasing Bn receptor affinity. Acid stripping studies demonstrated that the radiolabeled agonist, but not the antagonist, was internalized in each cell system. Bn receptor affinities for various Bn receptor agonists or antagonists in each cell system were identical when computed from an analysis of inhibition curves for binding of radiolabeled agonist or antagonist. However, with AR42J cells and 3T3 cells the radiolabeled agonist demonstrated a > 2-fold higher number of Bn receptors than did the radiolabeled antagonist. Binding studies using cell membranes, in contrast to cells, showed equal numbers of Bn receptors with either radiolabeled ligand. The radiolabeled agonist demonstrated high affinity binding to both rat pancreatic acinar and esophageal muscularis mucosa membranes, whereas the radiolabeled antagonist interacted with high affinity only with the gastrin-releasing peptide-preferring subtype of Bn receptors on pancreatic tissue. These results demonstrate that 125I-[D-Tyr6]Bn(6-13)ME is a high affinity radiolabeled antagonist that interacts specifically with Bn receptors. In contrast to the radiolabeled agonist, binding of the antagonist is not affected by guanine nucleotides and it is not internalized, which allows quantitation of only Bn cell surface receptors. Furthermore, the radiolabeled antagonist can distinguish Bn receptor subtypes, whereas the radiolabeled agonist does not. This ligand should prove useful for characterizing Bn receptors as well as studying their regulation.

Ligand binding, internalization, degradation and regulation by guanine nucleotides of bombesin receptor subtypes: a comparative study

Recent cloning studies confirm two subtypes of Bn receptors exist, a neuromedin B-preferring receptor (NMB-R) and a gastrin-releasing peptide-preferring receptor (GRP-R). Both subtypes occur widely in GI tract and the CNS; however, in contrast to the GRP-R subtype little is known about the ligand-receptor interactions for the NMB-R. Therefore, in the present study we explored the ligand-receptor interactions including kinetics, stoichiometry, internalization, degradation and regulation by guanine nucleotide binding proteins with the NMB-R and compared it to the GRP-R. The rat glioblastoma C-6 cell line which possess functional NMB-R and 3T3 cells which possess functional GRP-R were used. 125I-[D-Tyr0]NMB and 125I-[Tyr4]Bn were prepared using Iodogen and purified on HPLC. At 37 degrees C binding of 125I-[D-Tyr0]NMB to NMB-R or 125I-[Tyr4]Bn to GRP-R was maximal by 5-15 min and decreased to 60-70% after 60 min. HPLC analysis of the 60 min supernatant showed that > 80% of each tracer was degraded. Addition of proteinase inhibitors had a varied inhibitory effect on degradation with the relative order of potency in C-6 cells being leupeptin > bacitracin < chymostatin > phosphoramidon >> bestatin and amastatin and 3T3 cells being bacitracin = phosphoramidon > leupeptin = bestatin > chymostatin > amastatin in 3T3 cells. By HPLC analysis addition of bacitracin prevented the degradation in both cell types. With both receptor subtypes dissociation of bound radioligands was slow, with 70-80% of either 125I-[D-Tyr0]NMB or 125I-[Tyr4]Bn remained cell-associated after 60 min suggesting possible peptide internalization. With an acid wash procedure to remove surface bound radioligands, 60% of the C-6 cell-associated 125I-[D-Tyr0]NMB and 52% of the 3T3 cell-associated 125I-[Tyr4]Bn were internalized after 30 min at 37 degrees C. With membranes from cells possessing either receptor subtype, the stable guanine nucleotide GPP(NH)P inhibited in a dose-dependent fashion binding of ligands. Computer analysis demonstrated that GPP(NH)P decreased receptor affinity for ligands to both receptor subtypes. These results demonstrated that NMB receptors, similar to GRP receptors and rapidly internalize bound agonists and rapidly degrade agonists. The ligand-receptor interaction is regulated by a guanine nucleotide binding protein for both Bn receptor subtypes.

Characterization of functional receptors for gastrointestinal hormones on human colon cancer cells

Studies demonstrate that some colon cancers possess receptors for various gastrointestinal hormones or neurotransmitters, the occupation of which can affect growth. These results are limited because frequently only a small number of tumors are studied, only 1 or 2 receptors are sought, and the effect on cell function is not investigated. In the present study, 10 recently characterized human colon cancer cell lines were studied to determine whether they possess receptors for any of 12 different gastrointestinal hormones or neurotransmitters and to determine whether these receptors mediate changes in cellular function. Each of the cell lines exhibited receptors for at least one radioligand. Receptors for vasoactive intestinal peptide (VIP) and muscarinic cholinergic agents occurred on 60%, bombesin and gastrin on 30%, beta-adrenergic agents and gastrin-releasing peptide (GRP) on 20%, and somatostatin, opiates, neuromedin B, and substance P on 10%. Analysis of [3H]N-methylscopolamine binding revealed a Kd of 0.2 nM for N-methylscopolamine with a binding capacity of 2500 sites/cell. With the agonist carbamylcholine, the receptor exhibited 2 classes of binding sites: one of high affinity (Kd 55 microM) representing 75% of the binding sites and one of low affinity (Kd 0.3 mM) representing 25% of the binding sites. Analysis of 125I-[Tyr4]bombesin binding revealed a receptor of high affinity (Kd 2.1 microM) with a binding capacity of 3300 sites/cell. Inhibition of binding by agonists revealed relative potencies of 125I-[Tyr4]bombesin greater than GRP much greater than neuromedin B, and two recently described antagonists were similar in potency to GRP. Analysis of 125I-VIP binding revealed a receptor having 2 classes of binding sites: one of high affinity (Kd 3.6 nM) and one of low affinity (Kd 1.7 microM) which represented the majority of the 5.5 x 10(6) binding sites/cell. The relative potencies of agonists were VIP greater than helodermin greater than peptide histidine methionine greater than secretin. Evaluation of biological activity mediated by the muscarinic cholinergic and bombesin receptors revealed an increase of intracellular calcium and of inositol triphosphate by specific receptor agonists. The presence or absence of receptors detected by binding correlated closely with the ability of selective receptor agonists to alter cell function. These results demonstrate the presence of several different receptors for gastrointestinal hormones or neurotransmitters, some described for the first time, on human colon cancer cell lines, including bombesin-related peptides, VIP, somatostatin, substance P, beta-adrenergic agents, calcitonin gene-related peptide, gastrin, muscarinic cholinergic agents, and opiates.(ABSTRACT TRUNCATED AT 400 WORDS)

Covalently cyclized agonist and antagonist analogues of bombesin and related peptides

During a search for possible cyclization points in shortened, potent bombesin agonists and antagonists, it was found that the joining of amino acid residues in positions 6 and 14 by various means resulted in retention of significant binding affinity for rat pancreatic acini and murine Swiss 3T3 cells. In one series of analogues, Cys residues in these positions were used for bridging via a disulfide bond. (D)-C-Q-W-A-V-G-H-L-C-NH2 retained significant binding affinity for rat pancreatic acini cells and was a full amylase releasing agonist (EC50 187 nM). Potency was markedly increased by substituting D-Ala for Gly (EC50 67 nM compared to 10 nM for its linear counterpart) and was decreased by substituting L-Cys for D-Cys in this analogue (EC50 214 nM), thus strongly suggesting stabilization of peptide folding by the D residues. Elimination of the COOH-terminal amino acid produces competitive antagonists in the linear analogues; however, (D)-C-Q-W-A-V-G-H-C-NH2 was devoid of activity. Likewise, cyclization to position 13 with the 14 amino acids intact to give (D)-C-Q-W-A-V-G-H-C-L-NH2 resulted in an almost inactive peptide. On the other hand, as in the linear series, the reduced peptide bond analogue, (D)-C-Q-W-A-V-(D)-A-H-L-psi (CH2NH)-C-NH2, was a receptor antagonist (IC50 5.7 mM), albeit much weaker than the corresponding linear analogues, but with no residual agonist activity. Direct head-to-tail cyclization was also tried. Both cyclo[(D)-F-Q-W-A-V-G-H-L-L] (EC50 346 nM) and the shorter cyclo [Q-W-A-V-G-H-L-L] (EC50 1236 nM) were full agonists. Elimination of the COOH-terminal residue in cyclo[(D)-p-Cl-F-Q-W-A-V-(D)-A-H-L] produced an agonist (EC50 716 nM) rather than an antagonist. These results provide support for the proposal that both bombesin agonists and antagonists adopt a folded conformation at their receptor(s). Furthermore, the retention of appreciable potencies using several cyclization strategies and chain lengths suggests that further optimization of these structures both in terms of potency and ring size is possible. Since these peptides have increased conformational restriction, they should begin to serve as useful substrates for NMR and molecular modeling studies aimed at comparing the obviously subtle differences between agonist and antagonist structures.

Pharmacokinetics of oral and intravenous omeprazole in patients with the Zollinger-Ellison syndrome

The pharmacokinetics and pharmacodynamics of oral and IV omeprazole after a single dose were studied in 9 patients with the Zollinger-Ellison syndrome to determine whether the increased dose required to control gastric acid hypersecretion could be explained on the basis of altered pharmacokinetics. Each patient was studied both after receiving a single IV bolus of omeprazole (40 mg) and after receiving a single oral dose of omeprazole (80 mg). Intravenous and oral omeprazole doses were administered 1 week apart. Gastric acid secretion and plasma concentrations of omeprazole after drug administration were determined in each patient. The area under the plasma concentration curve, clearance, and volume of distribution after IV omeprazole administration and the area under the plasma concentration curve, peak plasma concentration, and time required to reach the peak after oral omeprazole administration were not different from those reported previously for normal subjects and patients with peptic ulcer disease. Mean (+/- SEM) bioavailability of oral omeprazole for all patients was 68% +/- 16%, which was similar to the bioavailability reported previously for normal subjects. Three patients had a significantly lower bioavailability reported previously for normal subjects. Three patients had a significantly lower bioavailability (20% +/- 8%) than the others, and their basal acid outputs were significantly higher than those of the other 7 patients. For all patients there was an inverse correlation between bioavailability and basal acid output (r = 0.76; P less than 0.02). The mean (+/- SEM) elimination half-lives of IV and oral omeprazole were not different (2.3 +/- 0.4 vs. 2.4 +/- 0.5 hours) but were significantly longer than those reported previously for normal subjects (P less than 0.02). The duration of action correlated with the elimination half-life of the drug (r = 0.87; P less than 0.003) and area under the plasma concentration curve (r = 0.72; P less than 0.03). The mean durations of action of IV and oral omeprazole were not significantly different (34 +/- 7.2 vs. 35 +/- 6.2 hours). It was concluded that altered pharmacokinetics do not account for the increased drug requirement of omeprazole in patients with the Zollinger-Ellison syndrome. In contrast to a previous study, the oral and IV omeprazole had the same duration of action, suggesting that intermittent bolus administration of parenteral omeprazole will obviate the need for continuous infusion of histamine H2-receptor antagonists in patients requiring parenteral antisecretory drugs. Furthermore, an IV dose every 12 hours controlled acid secretion in all patients, suggesting this as the recommended dose interval in patients requiring parenteral drug therapy.

Use of omeprazole in patients with Zollinger-Ellison syndrome

Omeprazole, a substituted benzimidazole, has been shown to be a potent inhibitor of gastric acid secretion in patients with Zollinger-Ellison syndrome (ZES). We review our experience, as well as the published data on 210 patients with ZES who have required omeprazole for control of gastric acid hypersecretion over the past seven years. The dose of omeprazole required in individual patients ranged from 10 to 180 mg/24 hr with 20-60% requiring a split dosage regimen. Omeprazole was effective in approximately 99% of the patients over a period ranging from 0.5 to 54 months. Twenty-four percent of patients required an increase in omeprazole dose, while 26% required a decrease in dose. Adverse effects attributable to omeprazole were reported in 2% of patients, and in all cases, they were mild (ie, rash, constipation, headache). There was no effect of omeprazole on serum gastrin concentration or on gastric endocrine cells in three studies. Although one patient with multiple endocrine neoplasia, type-I syndrome (MEN-I) in this series developed a gastric carcinoid while taking omeprazole, evidence is presented that suggests the presence of MEN-I per se may be important in determining the development of gastric carcinoid in patients with ZES. It is concluded that omeprazole is safe and effective in patients with ZES, and in these patients, it is the drug of choice for the management of gastric acid hypersecretion. However, yearly assessment is indicated to clearly evaluate the long-term risk of gastric carcinoid as well as therapy directed at the gastrinoma itself.

Cholera toxin inhibits signal transduction by several mitogens and the in vitro growth of human small-cell lung cancer

Cholera toxin (CT) inhibited the in vitro growth of three of four human small-cell lung carcinoma (SCLC) cell lines with a 50% inhibitory concentration of 27-242 ng/ml. Loss of surface membrane ruffling and the capacity of [Tyr4]-bombesin, vasopressin, and fetal calf serum to stimulate increases in intracellular free calcium clearly preceded effects on cellular metabolic activity and cell growth. 125I-[Tyr4]-bombesin binding was unaffected by CT treatment but [Tyr4]-bombesin stimulated phospholipase C activity was decreased in membranes from CT-treated SCLC cells. CT stimulated a rapid but transient increase in intracellular cyclic AMP ([cAMP]i) in SCLC. The effects of CT on susceptible SCLC were not reproduced by elevations of [cAMP]i induced by forskolin or cyclic AMP analogues. GM1 ganglioside, the cellular binding site for CT, was highly expressed in the CT-sensitive but not the CT-resistant SCLC cell lines. In contrast, expression of guanine nucleotide binding protein substrates for ADP-ribosylation by CT was similar. These data demonstrate the existence of a CT-sensitive growth inhibitory pathway in SCLC-bearing GM1 ganglioside. Addition of CT results in decreased responsiveness to several mitogenic stimuli. These results suggest novel therapeutic approaches to human SCLC.

Detection of duodenal gastrinomas by operative endoscopic transillumination. A prospective study

The ability of operative endoscopic transillumination of the bowel wall to detect duodenal gastrinoma was evaluated prospectively in 26 patients with the Zollinger-Ellison syndrome. The results were assessed by exploratory laparotomy and compared with the results of other localization techniques. Twelve duodenal gastrinomas were resected from 10 patients. Operative endoscopic transillumination detected 10 of the 12 gastrinomas, a sensitivity of 83%, which was significantly greater (P less than 0.05) than that for either preoperative imaging (25%) or intraoperative ultrasonography and palpation (42%). The sensitivity of operative endoscopic transillumination was a result of the ability to detect focal areas that did not transilluminate on the serosal side of the duodenum, and not the mucosal appearances seen through the endoscope, which were not helpful. Operative endoscopic transillumination detected gastrinomas less than 1 cm in diameter throughout the duodenum. Of the patients in this study, 39% had duodenal gastrinomas, a greater frequency than previously reported. These results indicate that operative endoscopic transillumination is the most sensitive technique yet described for detecting duodenal gastrinomas and should be performed routinely in all patients with the Zollinger-Ellison syndrome who undergo exploratory laparotomy for cure.

des-Met carboxyl-terminally modified analogues of bombesin function as potent bombesin receptor antagonists, partial agonists, or agonists

In the present study we examined the effect of carboxyl-terminal modifications of des-Met14-bombesin (Bn) on Bn receptor affinity in murine 3T3 cells, rat and guinea pig pancreatic acini, and the ability to initiate biologic responses by synthesizing 18 des-Met14-Bn(6-13) analogues. With guinea pig acini and 3T3 cells, affinity was affected by the chain length of the alkyl moiety (R) added to [D-Phe6]Bn(6-13)NH2R with relative potencies: propyl greater than ethyl greater than butyl = hexyl greater than heptyl greater than free amide, whereas in rat acini affinity was not increased by the chain length. In each cell system the affinity of the alkylamide was not increased by insertion of a phenyl group in the alkyl side chain, by making the analogue more neuromedin B-like or by addition of a reduced peptide bond. The affinity in each cell system was increased by additions of other electron releasing groups to the COOH-terminal carboxyl group such as [D-Phe6]Bn(6-13)ethyl or methyl ester, or hydrazide. In guinea pig pancreas and 3T3 cells, 12 analogues were antagonists, 1 a full and 5 partial agonists. In rat pancreas, 8 were antagonists, 5 full agonists, and 5 partial agonists. Potent antagonists in each cell system were the methyl and ethyl ester, hydrazide, and ethylamide analogues. In 3T3 cells or guinea pig pancreas, agonist activity of the alkylamide was critically dependent on the chain length, whereas with rat pancreatic Bn receptors any alkylamide longer than the ethylamide had agonist activity. In all three cell systems any alteration that made the alkylamide more neuromedin B-like caused agonist activity. These results demonstrate that the nature of the substitution on the carboxyl terminus of des-Met14-Bn analogues is critically important, not only for determining Bn receptor affinity, but also for determining the ability to initiate a biologic response. In contrast to previous studies, the present results demonstrate that the presence of the COOH-terminal amino acid in position 14 of Bn is not essential for initiating a biologic response. Several des-Met14-Bn analogues were potent partial agonists, whereas others such as the hydrazide or ethyl ester are very potent antagonists.

Intravenous omeprazole in patients with Zollinger-Ellison syndrome undergoing surgery

Twenty patients with Zollinger-Ellison syndrome who were undergoing surgery were studied prospectively to assess the efficacy and safety of IV omeprazole. During the preoperative period, in 19 of 20 patients, omeprazole 60 mg administered as an IV bolus every 12 hours inhibited acid output to less than 5 mEq/h measured in the last hour before the next dose of drug. In one patient, acid output was 25 mEq/h 12 hours after omeprazole, 60 mg, and increasing the dose to 100 mg every 12 hours reduced acid output to less than 5 mEq/h. During the operative and postoperative periods, IV omeprazole controlled gastric acid hypersecretion in all patients for up to 15 days. During this time, all patients received the dose determined preoperatively. No patient developed any clinical, hematological, or biochemical toxicity that could be attributed to omeprazole therapy during the preoperative or postoperative period. The present study demonstrates that omeprazole administered by IV bolus is safe and effective for controlling gastric acid hypersecretion. In contrast to IV histamine H2-receptor antagonists, IV omeprazole has the advantages of not requiring continuous infusion or postoperative dose adjustments. Intravenous omeprazole will become the drug of choice in patients with Zollinger-Ellison syndrome undergoing surgery.

Characteristics of cell lines established from human gastric carcinoma

We report the establishment and characterization of four continuous cell lines derived from human primary and metastatic gastric carcinomas, and we compare their properties with a panel of colorectal carcinoma cell lines previously established and reported by us. Our success rate in culturing gastric carcinomas was relatively low, especially from primary tumors, compared to colorectal carcinoma. These observations may reflect the relatively modest number of gastric carcinoma cell lines established (mainly from Japan), compared to the abundance of colorectal carcinoma lines established worldwide. All four gastric lines expressed the surface glycoproteins carcinoembryonic antigen and TAG-72 and three lines expressed CA 19-9. Two of the lines expressed aromatic amino acid decarboxylase but lacked other markers for neuroendocrine differentiation. All four lines were positive for vasoactive intestinal peptide receptors but lacked gastrin receptors. In addition, two lines expressed receptors for muscarinic/cholinergic receptors but not beta-adrenergic receptors. Cytogenetic evidence for gene amplification was present in the cell lines. All four lines contained varying numbers of double-minute chromosomes. One line, SNU-16, was amplified for the c-myc proto-oncogene and contained four homogeneously staining regions. While c-myc and c-erb-B-2 RNA were expressed by all lines, there was no evidence of amplification or overexpression of several other proto-oncogenes and growth factors. The multiple properties we have described in our gastric carcinoma cell lines are remarkably similar to those found in the panel of colorectal carcinoma cell lines. These properties include morphology, growth characteristics, expression of surface glycoproteins, partial expression of neuroendocrine cell markers, frequent chromosomal evidence of gene amplification, and occasional amplification of the c-myc proto-oncogene. Our four well characterized cell lines should provide useful additions to the modest number currently available for in vitro studies of gastric carcinoma.

Zollinger-Ellison syndrome. Recent advances in the management of the gastrinoma

Because of increasingly effective oral antisecretory agents, gastric acid hypersecretion is now able to be controlled in all patients with Zollinger-Ellison syndrome with the result that the natural history of the gastrinoma is becoming the major determinant of long-term survival. In this article recent advances in the management of the gastrinoma itself are reviewed, including results with new modalities such as intraoperative ultrasound, MRI, and selective gastrin sampling to localize gastrinoma in patients with Zollinger-Ellison syndrome, as well as recent results of the treatment of metastatic and localized gastrinomas.

Reflux esophagitis in patients with Zollinger-Ellison syndrome

The incidence of ulcers of the stomach and duodenum and their response to medical therapy, in patients with Zollinger-Ellison syndrome is well described. However, reflux esophagitis is less well recognized. In this study we determined the frequency of reflux esophagitis in 122 patients with Zollinger-Ellison syndrome and examined their response to medical therapy. Esophageal symptoms, endoscopic abnormalities, or both were present in 61% of patients. Forty-five percent of patients had esophageal symptoms consisting of heartburn, dysphagia, or both. Forty-three percent of patients had endoscopic abnormalities of the esophagus, and 23% demonstrated moderate or severe disease. When sufficient antisecretory medication was administered to lower gastric acid secretion to less than 10 mEq/h in the last hour before the next dose of drug, 67% of the patients with reflux esophagitis responded with complete disappearance of symptoms and normalization of the endoscopic abnormalities. The other 33% of patients required an increase in medication to lower acid output to less than 5 mEq/h in 7% and less than 1 mEq/h in the other 26% to resolve symptoms and signs completely. We conclude that reflux esophagitis occurs in the majority of patients with Zollinger-Ellison syndrome and responds well to medical therapy, although one third of patients require intensive antisecretory medication.

Desmethionine alkylamide bombesin analogues: a new class of bombesin receptor antagonists with potent antisecretory activity in pancreatic acini and antimitotic activity in Swiss 3T3 cells

Bombesin-related peptides have a large number of physiological functions as well as having an autocrine growth mechanism for the regulation of small cell lung cancer cells. In the present study we have synthesized 21 des-Met amide or alkylamide analogues of bombesin and compared their abilities to function as bombesin receptor antagonists in guinea pig pancreatic acini and Swiss 3T3 cells with those of the previously most potent antagonist described, [Leu13 psi(CH2NH)Leu14]bombesin (analogue I). All des-Met analogues functioned as antagonists. Bn(1-13)NH2 was approximately equipotent to I (Ki = 60-80 nM) whereas Bn(6-13)NH2 was 30-fold less potent (Ki = 1800 nM). Formation of an ethylamide, Bn(6-13)ethylamide, increased the potency 30-fold such that this octapeptide was equipotent to I. The addition of a D-Phe6 moiety to I did not change potency but caused a 30-fold increase in potency of Bn(6-13)NH2 and a 8-fold increase in the potency of Bn(6-13)ethylamide (Ki = 16 nM). Additional studies of both NH2- and COOH-terminal alterations in Bn(6-13)NH2 demonstrated that the most potent antagonist was [D-Phe6]Bn(6-13)propylamide (PA), having IC50's of 1.6 nM and 0.8 nM for bombesin-stimulated amylase release and Swiss 3T3 cell growth, respectively. Detailed studies of the most potent amide analogue, [D-Phe6]Bn(6-13)NH2, and alkylamide analogue, [D-Phe6]Bn(6-13)PA, demonstrated that these analogues functioned as competitive antagonists and that their action was selective for the bombesin receptor. These results demonstrate that, as with CCK- and gastrin-related peptides, the C-terminal amino acid is important for initiating a biologic response but not essential for determining receptor affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective study of the standard meal provocative test in Zollinger-Ellison syndrome

PURPOSE

The purpose of this work was to evaluate the proposed usefulness of a standard meal-stimulated gastrin provocative test in: (1) distinguishing Zollinger-Ellison syndrome (ZES) from antral syndromes; (2) localizing duodenal gastrinomas; or (3) suggesting that patients with multiple endocrine neoplasia type I (MEN-I) may have an increased incidence of antral syndromes.

PATIENTS AND METHODS

Seventy-four consecutive patients with ZES referred to the National Institutes of Health were studied prospectively. The extent and location of gastrinomas, acid secretory studies, and the presence or absence of MEN-I were determined and correlated with the results of the gastrin response to standard meal provocative testing.

RESULTS

For patients with fasting serum gastrin levels less than 1,000 pg/mL (n = 43), only 44% had a less than 50% increase over the pre-meal value, which is reported to be the typical response in ZES, and 40% had a 50% to 99% increase. Furthermore 16% had a 100% or greater increase, 9% a 150% or greater increase, and 5% a 200% or greater increase, which overlaps with values reported to be characteristic of 98%, 92%, and 46% of patients with antral syndromes. Results did not differ for patients with or without MEN-I, depend on the extent of the gastrinoma (duodenal versus pancreatic gastrinomas), the presence of previous gastric surgery or type of gastric surgery, or for patients with fasting serum gastrin concentrations greater than or equal to 1,000 pg/mL or less than 1,000 pg/mL. studies of four patients before and after resection of the gastrinoma, who prior to surgery had a greater than 100% increase in gastrin secretion after the meal, demonstrated that all patients had a less than 100% increase postoperatively even though no gastric resection was done.

CONCLUSIONS

Approximately half of the patients with ZES have a greater than 50% increase in serum gastrin concentration following a standard test meal and one fifth have a 100% or greater increase. Therefore, they cannot be distinguished on this basis from patients with antral syndromes. The increased serum gastrin level after the meal in these patients with ZES appears to be due to the gastrinoma. Furthermore, the current study provides no evidence for the proposals that antral syndromes are more common in patients with MEN-I, that gastric surgery affects the meal response in patients with gastrinomas, or that the meal test is useful in localizing duodenal gastrinomas.