Suppression of Peutz-Jeghers polyposis by inhibition of cyclooxygenase-2

Progress report: Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is a rare, autosomal dominant polyposis syndrome. Presenting with a remarkable phenotype including development of characteristic gastrointestinal polyps, mucocutaneous pigmentations, and an increased risk of cancer, the syndrome has been subject to many studies concerning the natural course of disease. In most patients, pathogenic germline variants are detected in the STK11 gene including cases of mosaicism and structural variants. Yet, studies assessing the effect of surveillance, understanding of cancer development, as well as clinical studies evaluating chemoprevention are lacking. In addition, the impact of Peutz-Jeghers syndrome on mental health, education, and family planning are insufficiently addressed. In this progress report, we describe current knowledge, clinical phenotype, surveillance strategies, and future areas of research.

Chemoprevention in hereditary digestive neoplasia: A comprehensive review

Hereditary syndromes, such as familial adenomatous polyposis (FAP), MUTYH polyposis or Lynch syndrome, are particularly predisposing to the development of colorectal cancer. These situations have necessitated the development of adapted prevention strategies based largely on reinforced endoscopic surveillance and the search for complementary prevention strategies. This is the case for chemoprevention, which is the long-term administration of chemical agents limiting carcinogenesis, used as primary or secondary prophylaxis. The aim of this review is to present the available literature and the latest advances in chemoprevention in patients with FAP or MUTYH and other polyposis as well as in patients with Lynch syndrome. The main conclusions of the few available guidelines in these situations are also discussed.

Cancer Risk of Peutz-Jeghers Syndrome and Treatment Experience: A Chinese Medical Center

Peutz-Jeghers syndrome (PJS), also known as hereditary mucocutaneous pigmented gastrointestinal polyposis, is a clinically rare autosomal dominant genetic disease, which falls into the category of hereditary colorectal cancer. There are ∼7,000 new cases of PJS in China every year, and 170,000 PJS patients may survive for a long time in society. PJS polyps are characterized by an early age of onset, difficult diagnosis and treatment, and easy recurrence. With repeated growth, polyps can lead to serious complications such as intestinal obstruction, intussusception, gastrointestinal bleeding, and cancerization, which cause serious clinical problems. Due to repeated hospitalization and endoscopic follow-up, PJS patients and their families suffer from great physical and mental pain and economic burden. With the in-depth understanding of PJS and the development and popularization of endoscopic techniques in the past decade, an integrated treatment modality based on endoscopy plus surgery has gradually become the preferred treatment in most hospitals, which greatly improves the quality of life of PJS patients. However, there is still a lack of effective drug prevention and cure means. In this paper, the current clinical treatment means for PJS polyps were summarized by literature review combined with the treatment experience of our medical center, with a focus on their clinical diagnosis, treatment, and cancer risk.

Preventive strategies in familial and hereditary colorectal cancer

Colorectal cancer is a leading cause of cancer-related deaths worldwide. While most cases are sporadic, a significant proportion of cases are associated with familial and hereditary syndromes. Individuals with a family history of colorectal cancer have an increased risk of developing the disease, and those with hereditary syndromes such as Lynch syndrome or familial adenomatous polyposis have a significantly higher risk. In these populations, preventive strategies are critical for reducing the incidence and mortality of colorectal cancer. This review provides an overview of current preventive strategies for individuals at increased risk of colorectal cancer due to familial or hereditary factors. The manuscript includes a discussion of risk assessment and genetic testing, highlighting the importance of identifying at-risk individuals and families. This review describes various preventive measures, including surveillance colonoscopy, chemoprevention, and prophylactic surgery, and their respective benefits and limitations. Together, this work highlights the importance of preventive strategies in familial and hereditary colorectal cancer.

Clinical features, diagnosis, and treatment of Peutz-Jeghers syndrome: Experience with 566 Chinese cases

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a clinically rare disease with pigmented spots on the lips and mucous membranes and extremities, scattered gastrointestinal polyps, and susceptibility to tumors as clinical manifestations. Effective preventive and curative methods are still lacking. Here we summarize our experience with 566 Chinese patients with PJS from a Chinese medical center with regard to the clinical features, diagnosis, and treatment.

AIM

To explore the clinical features, diagnosis, and treatment of PJS in a Chinese medical center.

METHODS

The diagnosis and treatment information of 566 cases of PJS admitted to the Air Force Medical Center from January 1994 to October 2022 was summarized. A clinical database was established covering age, gender, ethnicity, family history, age at first treatment, time and sequence of appearance of mucocutaneous pigmentation, polyp distribution, quantity, and diameter, frequency of hospitalization, frequency of surgical operations, etc. The clinical data was retrospectively analyzed using SPSS 26.0 software, with P < 0.05 considered statistically significant.

RESULTS

Of all the patients included, 55.3% were male and 44.7% were female. Median time to the appearance of mucocutaneous pigmentation was 2 years, and median time from the appearance of mucocutaneous pigmentation to the occurrence of abdominal symptoms was 10 years. The vast majority (92.2%) of patients underwent small bowel endoscopy and treatment, with 2.3% having serious complications. There was a statistically significant difference in the number of enteroscopies between patients with and without canceration (P = 0.004, Z = -2.882); 71.2% of patients underwent surgical operation, 75.6% of patients underwent surgical operation before the age of 35 years, and there was a statistically significant difference in the frequency of surgical operations between patients with and without cancer (P = 0.000, Z = -5.127). At 40 years of age, the cumulative risk of intussusception in PJS was approximately 72.0%, and at 50 years, the cumulative risk of intussusception in PJS was approximately 89.6%. At 50 years of age, the cumulative risk of cancer in PJS was approximately 49.3%, and at 60 years of age, the cumulative risk of cancer in PJS was approximately 71.7%.

CONCLUSION

The risk of intussusception and cancer of PJS polyps increases with age. PJS patients ≥ 10 years old should undergo annual enteroscopy. Endoscopic treatment has a good safety profile and can reduce the occurrence of polyps intussusception and cancer. Surgery should be conducted to protect the gastrointestinal system by removing polyps.

Clinical features, diagnosis, and treatment of Peutz-Jeghers syndrome: Experience with 566 Chinese cases

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a clinically rare disease with pigmented spots on the lips and mucous membranes and extremities, scattered gastrointestinal polyps, and susceptibility to tumors as clinical manifestations. Effective preventive and curative methods are still lacking. Here we summarize our experience with 566 Chinese patients with PJS from a Chinese medical center with regard to the clinical features, diagnosis, and treatment.

AIM

To explore the clinical features, diagnosis, and treatment of PJS in a Chinese medical center.

METHODS

The diagnosis and treatment information of 566 cases of PJS admitted to the Air Force Medical Center from January 1994 to October 2022 was summarized. A clinical database was established covering age, gender, ethnicity, family history, age at first treatment, time and sequence of appearance of mucocutaneous pigmentation, polyp distribution, quantity, and diameter, frequency of hospitalization, frequency of surgical operations, etc. The clinical data was retrospectively analyzed using SPSS 26.0 software, with P < 0.05 considered statistically significant.

RESULTS

Of all the patients included, 55.3% were male and 44.7% were female. Median time to the appearance of mucocutaneous pigmentation was 2 years, and median time from the appearance of mucocutaneous pigmentation to the occurrence of abdominal symptoms was 10 years. The vast majority (92.2%) of patients underwent small bowel endoscopy and treatment, with 2.3% having serious complications. There was a statistically significant difference in the number of enteroscopies between patients with and without canceration (P = 0.004, Z = -2.882); 71.2% of patients underwent surgical operation, 75.6% of patients underwent surgical operation before the age of 35 years, and there was a statistically significant difference in the frequency of surgical operations between patients with and without cancer (P = 0.000, Z = -5.127). At 40 years of age, the cumulative risk of intussusception in PJS was approximately 72.0%, and at 50 years, the cumulative risk of intussusception in PJS was approximately 89.6%. At 50 years of age, the cumulative risk of cancer in PJS was approximately 49.3%, and at 60 years of age, the cumulative risk of cancer in PJS was approximately 71.7%.

CONCLUSION

The risk of intussusception and cancer of PJS polyps increases with age. PJS patients ≥ 10 years old should undergo annual enteroscopy. Endoscopic treatment has a good safety profile and can reduce the occurrence of polyps intussusception and cancer. Surgery should be conducted to protect the gastrointestinal system by removing polyps.

Clinical Spectrum and Science Behind the Hamartomatous Polyposis Syndromes

The hamartomatous polyposis syndromes are a set of clinically distinct disorders characterized by the occurrence of hamartomatous polyps in the gastrointestinal tract. These syndromes include juvenile polyposis syndrome, Peutz-Jeghers syndrome, and PTEN hamartoma tumor syndrome. Although each of the syndromes has distinct phenotypes, the hamartomatous polyps can be challenging to differentiate histologically. Additionally, each of these syndromes is associated with increased lifetime risks of gene-specific and organ-specific cancers, including those outside of the gastrointestinal tract. Germline pathogenic variants can be identified in a subset of individuals with these syndromes, which facilitates molecular diagnosis and subsequent gene-enabled management in the setting of genetic counseling. Although the malignant potential of hamartomatous polyps remains elusive, timely recognition of these syndromes is important and enables presymptomatic cancer surveillance and management before symptom exacerbation. Presently, there are no standard agents to prevent the development of polyps and cancers in the hamartomatous polyposis syndromes.

Altered Gut Microbiota in Patients With Peutz–Jeghers Syndrome

Background

Peutz–Jeghers syndrome (PJS) is a rare genetic disorder characterized by the development of pigmented spots and gastrointestinal polyps and increased susceptibility to cancers. It remains unknown whether gut microbiota dysbiosis is linked to PJS.

Aim

This study aimed to assess the structure and composition of the gut microbiota, including both bacteria and fungi, in patients with PJS and investigate the relationship between gut microbiota dysbiosis and PJS pathogenesis.

Methods

The bacterial and fungal composition of the fecal microbiota was analyzed in 23 patients with PJS (cases), 17 first-degree asymptomatic relatives (ARs), and 24 healthy controls (HCs) using 16S (MiSeq) and ITS2 (pyrosequencing) sequencing for bacteria and fungi, respectively. Differential analyses of the intestinal flora were performed from the phylum to species level.

Results

Alpha-diversity distributions of bacteria and fungi indicated that the abundance of both taxa differed between PJS cases and controls. However, while the diversity and composition of fecal bacteria in PJS cases were significantly different from those in ARs and HCs, fungal flora was more stable. High-throughput sequencing confirmed the special characteristics and biodiversity of the fecal bacterial and fungal microflora in patients with PJS. They had lower bacterial biodiversity than controls, with a higher frequency of the Proteobacteria phylum, Enterobacteriaceae family, and Escherichia-Shigella genus, and a lower frequency of the Firmicutes phylum and the Lachnospiraceae and Ruminococcaceae families. Of fungi, Candida was significantly higher in PJS cases than in controls.

Conclusion

The findings reported here confirm gut microbiota dysbiosis in patients with PJS. This is the first report on the bacterial and fungal microbiota profile of subjects with PJS, which may be meaningful to provide a structural basis for further research on intestinal microecology in PJS.

Diagnosis and Management of Cancer Risk in the Gastrointestinal Hamartomatous Polyposis Syndromes: Recommendations From the US Multi-Society Task Force on Colorectal Cancer

The gastrointestinal hamartomatous polyposis syndromes are rare, autosomal dominant disorders associated with an increased risk of benign and malignant intestinal and extraintestinal tumors. They include Peutz-Jeghers syndrome, juvenile polyposis syndrome, the PTEN hamartoma tumor syndrome (including Cowden's syndrome and Bannayan-Riley-Ruvalcaba syndrome), and hereditary mixed polyposis syndrome. Diagnoses are based on clinical criteria and, in some cases, confirmed by demonstrating the presence of a germline pathogenic variant. The best understood hamartomatous polyposis syndrome is Peutz-Jeghers syndrome, caused by germline pathogenic variants in the STK11 gene. The management is focused on prevention of bleeding and mechanical obstruction of the small bowel by polyps and surveillance of organs at increased risk for cancer. Juvenile polyposis syndrome is caused by a germline pathogenic variant in either the SMAD4 or BMPR1A genes, with differing clinical courses. Patients with SMAD4 pathogenic variants may have massive gastric polyposis, which can result in gastrointestinal bleeding and/or protein-losing gastropathy. Patients with SMAD4 mutations usually have the simultaneous occurrence of hereditary hemorrhagic telangiectasia (juvenile polyposis syndrome-hereditary hemorrhagic telangiectasia overlap syndrome) that can result in epistaxis, gastrointestinal bleeding from mucocutaneous telangiectasias, and arteriovenous malformations. Germline pathogenic variants in the PTEN gene cause overlapping clinical phenotypes (known as the PTEN hamartoma tumor syndromes), including Cowden's syndrome and related disorders that are associated with an increased risk of gastrointestinal and colonic polyposis, colon cancer, and other extraintestinal manifestations and cancers. Due to the relative rarity of the hamartomatous polyposis syndromes, recommendations for management are based on few studies. This U.S Multi-Society Task Force on Colorectal Cancer consensus statement summarizes the clinical features, assesses the current literature, and provides guidance for diagnosis, assessment, and management of patients with the hamartomatous polyposis syndromes, with a focus on endoscopic management.

Diagnosis and management of cancer risk in the gastrointestinal hamartomatous polyposis syndromes: recommendations from the U.S. Multi-Society Task Force on Colorectal Cancer

The gastrointestinal hamartomatous polyposis syndromes are rare, autosomal dominant disorders associated with an increased risk of benign and malignant intestinal and extraintestinal tumors. They include Peutz-Jeghers syndrome, juvenile polyposis syndrome, the PTEN hamartoma tumor syndrome (including Cowden's syndrome and Bannayan-Riley-Ruvalcaba syndrome), and hereditary mixed polyposis syndrome. Diagnoses are based on clinical criteria and, in some cases, confirmed by demonstrating the presence of a germline pathogenic variant. The best understood hamartomatous polyposis syndrome is Peutz-Jeghers syndrome, caused by germline pathogenic variants in the STK11 gene. The management is focused on prevention of bleeding and mechanical obstruction of the small bowel by polyps and surveillance of organs at increased risk for cancer. Juvenile polyposis syndrome is caused by a germline pathogenic variant in either the SMAD4 or BMPR1A genes, with differing clinical courses. Patients with SMAD4 pathogenic variants may have massive gastric polyposis, which can result in gastrointestinal bleeding and/or protein-losing gastropathy. Patients with SMAD4 mutations usually have the simultaneous occurrence of hereditary hemorrhagic telangiectasia (juvenile polyposis syndrome-hereditary hemorrhagic telangiectasia overlap syndrome) that can result in epistaxis, gastrointestinal bleeding from mucocutaneous telangiectasias, and arteriovenous malformations. Germline pathogenic variants in the PTEN gene cause overlapping clinical phenotypes (known as the PTEN hamartoma tumor syndromes), including Cowden's syndrome and related disorders that are associated with an increased risk of gastrointestinal and colonic polyposis, colon cancer, and other extraintestinal manifestations and cancers. Due to the relative rarity of the hamartomatous polyposis syndromes, recommendations for management are based on few studies. This U.S. Multi-Society Task Force on Colorectal Cancer consensus statement summarizes the clinical features, assesses the current literature, and provides guidance for diagnosis, assessment, and management of patients with the hamartomatous polyposis syndromes, with a focus on endoscopic management.

Diagnosis and Management of Cancer Risk in the Gastrointestinal Hamartomatous Polyposis Syndromes: Recommendations From the US Multi-Society Task Force on Colorectal Cancer

The gastrointestinal hamartomatous polyposis syndromes are rare, autosomal dominant disorders associated with an increased risk of benign and malignant intestinal and extraintestinal tumors. They include Peutz-Jeghers syndrome, juvenile polyposis syndrome, the PTEN hamartoma tumor syndrome (including Cowden's syndrome and Bannayan-Riley-Ruvalcaba syndrome), and hereditary mixed polyposis syndrome. Diagnoses are based on clinical criteria and, in some cases, confirmed by demonstrating the presence of a germline pathogenic variant. The best understood hamartomatous polyposis syndrome is Peutz-Jeghers syndrome, caused by germline pathogenic variants in the STK11 gene. The management is focused on prevention of bleeding and mechanical obstruction of the small bowel by polyps and surveillance of organs at increased risk for cancer. Juvenile polyposis syndrome is caused by a germline pathogenic variant in either the SMAD4 or BMPR1A genes, with differing clinical courses. Patients with SMAD4 pathogenic variants may have massive gastric polyposis, which can result in gastrointestinal bleeding and/or protein-losing gastropathy. Patients with SMAD4 mutations usually have the simultaneous occurrence of hereditary hemorrhagic telangiectasia (juvenile polyposis syndrome-hereditary hemorrhagic telangiectasia overlap syndrome) that can result in epistaxis, gastrointestinal bleeding from mucocutaneous telangiectasias, and arteriovenous malformations. Germline pathogenic variants in the PTEN gene cause overlapping clinical phenotypes (known as the PTEN hamartoma tumor syndromes), including Cowden's syndrome and related disorders that are associated with an increased risk of gastrointestinal and colonic polyposis, colon cancer, and other extraintestinal manifestations and cancers. Due to the relative rarity of the hamartomatous polyposis syndromes, recommendations for management are based on few studies. This US Multi-Society Task Force on Colorectal Cancer consensus statement summarizes the clinical features, assesses the current literature, and provides guidance for diagnosis, assessment, and management of patients with the hamartomatous polyposis syndromes, with a focus on endoscopic management.

Gastrointestinal aspects of Peutz-Jeghers syndrome

There are two main problems in the clinical management of the gastrointestinal (GI) tract in patients with Peutz-Jeghers syndrome (PJS), namely long-term cancer risk and managing polyp related complications (of which the most important clinically is intussusception). Given the rarity of this condition, the evidence base upon which to make recommendations is small. Furthermore, controversies persist regarding the relationship between PJ polyps, cancer development and cancer risk. In this article we will explore some of these controversies, to put into context the recommendations for clinical management of these patients. We will provide an overview, particularly focusing on clinical data, and on the recommendations for clinical management and surveillance of the GI tract in PJS. We highlight knowledge gaps which need to be addressed by further research.

Chemoprevention Considerations in Patients with Hereditary Colorectal Cancer Syndromes

Secondary prevention of colorectal neoplasia with chemoprevention is long-studied area of research and clinical use in patients with the 2 most common hereditary colorectal cancer syndromes including Lynch syndrome and familial adenomatous polyposis. No medication is currently approved for use for the prevention of colorectal polyps or cancer in either the general population or individuals with the hereditary colorectal cancer syndromes. Emerging data in animal models and limited data in humans suggest vaccines may be the next breakthrough for neoplasia prevention in patients with hereditary colorectal cancer. Clinicians must acknowledge chemoprevention is an adjunct and does not supplant endoscopic surveillance.

Peutz-Jeghers Syndrome and the Role of Imaging: Pathophysiology, Diagnosis, and Associated Cancers

Simple Summary

The Peutz-Jeghers Syndrome is a rare autosomal dominant syndrome characterized by mucocutaneous pigmentations, multiple gastrointestinal hamartomatous polyps, and an elevated risk of malignancy. Awareness of various Peutz-Jeghers Syndrome imaging patterns, associated malignancies, and their complications is crucial for accurate imaging interpretation and patient management. In this manuscript, we provide an overview of this condition, associated malignancies, and imaging surveillance protocols.

Abstract

The Peutz-Jeghers Syndrome (PJS) is an autosomal dominant neoplastic syndrome defined by hamartomatous polyps through the gastrointestinal tract, development of characteristic mucocutaneous pigmentations, and an elevated lifetime cancer risk. The majority of cases are due to a mutation in the STK11 gene located at 19p13.3. The estimated incidence of PJS ranges from 1:50,000 to 1:200,000. PJS carries an elevated risk of malignancies including gastrointestinal, breast, lung, and genitourinary (GU) neoplasms. Patients with PJS are at a 15- to 18-fold increased malignancy risk relative to the general population. Radiologists have an integral role in the diagnosis of these patients. Various imaging modalities are used to screen for malignancies and complications associated with PJS. Awareness of various PJS imaging patterns, associated malignancies, and their complications is crucial for accurate imaging interpretation and patient management. In this manuscript, we provide a comprehensive overview of PJS, associated malignancies, and surveillance protocols.

Malignant tumors associated with Peutz-Jeghers syndrome: Five cases from a single surgical unit

BACKGROUND

Peutz-Jeghers syndrome (PJS) is an autosomal dominant inherited disease easily causing secondary malignant changes without effective treatments.

AIM

To assess the clinical characteristics, diagnosis, and treatment of malignant changes secondary to PJS.

METHODS

The clinical data of five patients with malignant changes secondary to PJS diagnosed and treated at Beijing Friendship Hospital from June 2014 to January 2017 were retrospectively analyzed; the follow-up ended in May 2018.

RESULTS

There were three male and two female patients with an average age of 43.6 years. Intestinal obstruction, intussusception, and abdominal pain were the first symptoms. Computed tomography and gastrointestinal imaging combined with endoscopy helped evaluate the depth of tumor infiltration and determine the need for radical resection. Three patients underwent surgery. Postoperative pathology confirmed adenocarcinoma, genetic test indicated STK11 mutation, and the patients received chemotherapy, including one who succumbed to tumor progression 6 months post-surgery. Other two patients underwent endoscopic resection, and postoperative pathology confirmed high grade intraepithelial neoplasia. The surviving patients had no recurrence by May 2018.

CONCLUSION

Endoscopy combined with computed tomography and gastrointestinal imaging is of great significance in the diagnosis and treatment of PJS, and pathological examination and gene detection are the gold standards for detecting malignant changes secondary to PJS. Some malignant polyps can be removed under endoscopy, and surgery is feasible when malignant polyps cannot be removed under an endoscope. For patients unable to achieve R0 resection, clinical symptoms should be relieved, and postoperative adjuvant chemotherapy could improve long-term prognosis. Meanwhile, close and regular surveillance should be conducted to prevent severe complications.

Stromal Lkb1 deficiency leads to gastrointestinal tumorigenesis involving the IL-11-JAK/STAT3 pathway

Germline mutations in the gene encoding tumor suppressor kinase LKB1 lead to gastrointestinal tumorigenesis in Peutz-Jeghers syndrome (PJS) patients and mouse models; however, the cell types and signaling pathways underlying tumor formation are unknown. Here, we demonstrated that mesenchymal progenitor- or stromal fibroblast-specific deletion of Lkb1 results in fully penetrant polyposis in mice. Lineage tracing and immunohistochemical analyses revealed clonal expansion of Lkb1-deficient myofibroblast-like cell foci in the tumor stroma. Loss of Lkb1 in stromal cells was associated with induction of an inflammatory program including IL-11 production and activation of the JAK/STAT3 pathway in tumor epithelia concomitant with proliferation. Importantly, treatment of LKB1-defcient mice with the JAK1/2 inhibitor ruxolitinib dramatically decreased polyposis. These data indicate that IL-11-mediated induction of JAK/STAT3 is critical in gastrointestinal tumorigenesis following Lkb1 mutations and suggest that targeting this pathway has therapeutic potential in Peutz-Jeghers syndrome.

Familial Gastric Cancers

Although the majority of gastric carcinomas are sporadic, approximately 10% show familial aggregation, and a hereditary cause is determined in 1%-3% cases. Of these, hereditary diffuse gastric cancer is the most recognized predisposition syndrome. Although rare, the less commonly known syndromes also confer a markedly increased risk for development of gastric cancer. Identification and characterization of these syndromes require a multidisciplinary effort involving oncologists, surgeons, genetic counselors, biologists, and pathologists. This article reviews the molecular genetics, clinical and pathologic features, surveillance guidelines, and preventive measures of common and less common hereditary gastric cancer predisposition syndromes.

[Hereditary predisposition to cancers of the digestive tract, breast, gynecological and gonadal: focus on the Peutz-Jeghers]

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disease due to mutations in the tumor suppressor gene STK11. PJS is characterized by periorificial hyperpigmented macules (lentiginosis) and hamartomatous polyposis. Polyps can be located anywhere in the gastrointestinal tract, but are preferably observed in the small bowel (70-90%), the colon (50%) and the stomach (25%). They tend to be cancerous in a particular sequence hamartoma-dysplasia-cancer. The diagnosis is often made in the first or second decade following the appearance of lentigines or upon the occurrence of complications due to polyps (obstruction, intussusception, occult bleeding responsible for anemia). Furthermore PJS is associated with a significant increase in cancer risk (relative risk of 89% over the life according to the most recent series). Digestive cancers are the more frequent with cumulative incidences of 55% for gastro-intestinal cancer (39% for colorectal cancer, 13% for small bowel cancer and between 11 and 36% for pancreatic cancer, respectively). There is also an increased risk of non digestive cancers. In particular the risk of breast cancer is similar to that of patients carrying deleterious BRCA1 or BRCA2 mutations (cumulative incidence of 45%). Gynecological and gonadal tumors are frequent as well and can be more (adenoma malignum) or less aggressive (ovarian sex cord tumors with annular tubules and testicular tumors with calcified Sertoli cells). Finally the frequency of lung cancer is moderately increased. Recommendations for screening and management based on retrospective series in the literature have led to various strategies. The aim of this paper is to summarize the clinical and molecular diagnostic criteria of PJS as well as recommendations on screening strategies, management and monitoring.

ACG clinical guideline: Genetic testing and management of hereditary gastrointestinal cancer syndromes

This guideline presents recommendations for the management of patients with hereditary gastrointestinal cancer syndromes. The initial assessment is the collection of a family history of cancers and premalignant gastrointestinal conditions and should provide enough information to develop a preliminary determination of the risk of a familial predisposition to cancer. Age at diagnosis and lineage (maternal and/or paternal) should be documented for all diagnoses, especially in first- and second-degree relatives. When indicated, genetic testing for a germline mutation should be done on the most informative candidate(s) identified through the family history evaluation and/or tumor analysis to confirm a diagnosis and allow for predictive testing of at-risk relatives. Genetic testing should be conducted in the context of pre- and post-test genetic counseling to ensure the patient's informed decision making. Patients who meet clinical criteria for a syndrome as well as those with identified pathogenic germline mutations should receive appropriate surveillance measures in order to minimize their overall risk of developing syndrome-specific cancers. This guideline specifically discusses genetic testing and management of Lynch syndrome, familial adenomatous polyposis (FAP), attenuated familial adenomatous polyposis (AFAP), MUTYH-associated polyposis (MAP), Peutz-Jeghers syndrome, juvenile polyposis syndrome, Cowden syndrome, serrated (hyperplastic) polyposis syndrome, hereditary pancreatic cancer, and hereditary gastric cancer.

Role of LKB1-CRTC1 on glycosylated COX-2 and response to COX-2 inhibition in lung cancer

BACKGROUND

Cyclooxygenase-2 (COX-2) directs the synthesis of prostaglandins including PGE-2 linking inflammation with mitogenic signaling. COX-2 is also an anticancer target, however, treatment strategies have been limited by unreliable expression assays and by inconsistent tumor responses to COX-2 inhibition.

METHODS

We analyzed the TCGA and Director's Challenge lung cancer datasets (n = 188) and also generated an LKB1-null lung cancer gene signature (n = 53) to search the Broad Institute/Connectivity-MAP (C-MAP) dataset. We performed ChIP analyses, real-time polymerase chain reaction, immunoblotting, and drug testing of tumor cell lines (n = 8) and primary lung adenocarcinoma surgical resections (n = 13).

RESULTS

We show that COX-2 is a target of the cAMP/CREB coactivator CRTC1 signaling pathway. In addition, we detected a correlation between LKB1 status, CRTC1 activation, and presence of glycosylated, but not inactive hypoglycosylated COX-2 in primary lung adenocarcinoma. A search of the C-MAP drug database discovered that all high-ranking drugs positively associated with the LKB1-null signature are known CRTC1 activators, including forskolin and six different PGE-2 analogues. Somatic LKB1 mutations are present in 20.0% of lung adenocarcinomas, and we observed growth inhibition with COX-2 inhibitors in LKB1-null lung cancer cells with activated CRTC1 as compared with LKB1-wildtype cells (NS-398, P = .002 and Niflumic acid, P = .006; two-tailed t test).

CONCLUSION

CRTC1 activation is a key event that drives the LKB1-null mRNA signature in lung cancer. We also identified a positive feedback LKB1/CRTC1 signaling loop for COX-2/PGE2 regulation. These data suggest a role for LKB1 status and glycosylated COX-2 as specific biomarkers that provide a framework for selecting patients for COX-2 inhibition studies.

Polyp Clearance via Operative and Endoscopic Polypectomy in Patients With Peutz-Jeghers Syndrome After Multiple Small Bowel Resections

Peutz-Jeghers syndrome is an autosomal dominant inherited disease that manifests as a combination of mucocutaneous pigmentation and gastrointestinal hamartomatous polyps that usually cause intussusception and intestinal hemorrhage. We report the case of a 40-year-old male patient who was diagnosed 20 years ago and had previously undergone 3 intestinal resection surgeries. This time, with the use of combined operative and endoscopic polypectomy, more than 100 polyps were removed. This technique is useful for providing a "clean" small intestine that allows the patient a long interval between laparotomies and reduces the complications associated with multiple laparotomies and resections.

Recent progress on liver kinase B1 (LKB1): expression, regulation, downstream signaling and cancer suppressive function

Liver kinase B1 (LKB1), known as a serine/threonine kinase, has been identified as a critical cancer suppressor in many cancer cells. It is a master upstream kinase of 13 AMP-activated protein kinase (AMPK)-related protein kinases, and possesses versatile biological functions. LKB1 gene is mutated in many cancers, and its protein can form different protein complexes with different cellular localizations in various cell types. The expression of LKB1 can be regulated through epigenetic modification, transcriptional regulation and post-translational modification. LKB1 dowcnstream pathways mainly include AMPK, microtubule affinity regulating kinase (MARK), salt-inducible kinase (SIK), sucrose non-fermenting protein-related kinase (SNRK) and brain selective kinase (BRSK) signalings, etc. This review, therefore, mainly discusses recent studies about the expression, regulation, downstream signaling and cancer suppressive function of LKB1, which can be helpful for better understanding of this molecular and its significance in cancers.

N-methylnitrosourea aggravates gastrointestinal polyposis in Lkb1+/- mice

Peutz-Jeghers patients develop hamartomatous polyps and carcinomas of the gastrointestinal tract. Cyclooxygenase-2 accelerates polyp growth in Lkb1 (+/-) mice modelling Peutz-Jeghers polyposis. In this study, we aimed to evaluate the effect of the mutagenic carcinogen N-methylnitrosourea (MNU) on gastrointestinal tumourigenesis in Lkb1 (+/-) mice and to investigate the role of cyclooxygenase-2 on the tumourigenesis. We treated 40 Lkb1 (+/-) and 51 wild-type mice with MNU, 10 mice from both groups received the cyclooxygenase-2 inhibitor celecoxib. Carcinogen-treated Lkb1 (+/-) mice displayed worse survival (60%) than treated wild-type (100%, P = 0.028) or untreated Lkb1 (+/-) mice (92%, P = 0.045). Also, the gastrointestinal tumour burden was almost 10-fold higher in carcinogen-treated (2181 mm(3)) than in untreated (237 mm(3), P = 0.00045) Lkb1 (+/-) mice. Celecoxib was much less efficient in reducing tumourigenesis in MNU-treated mice (by 23%; 1686 mm(3)) than in untreated mice (76%; 58 mm(3)). Surprisingly, the increase in tumour burden in MNU-treated mice was not accompanied by consistent histological changes, with only a single focus of epithelial dysplasia noted. This study suggests that MNU promotes Peutz-Jeghers polyposis independently from the acceleration by cyclooxygenase-2.

Targeting LKB1 signaling in cancer

The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.

Cyclooxygenase-2 and gastric cancer

Gastric cancer remains a leading cause of cancer-related deaths worldwide, although its incidence has been steadily declining during recent decades. Expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. COX-2 expression associates with reduced survival in gastric cancer patients, and it has also been shown to be an independent factor of poor prognosis. Several molecular mechanisms are involved in the regulation of COX-2 expression in gastric cancer cell lines, including signal transduction pathways activated by Helicobacter pylori. In gastric tumor models in vivo the role of COX-2 seems to be predominantly to facilitate tumor promotion and growth.

LKB1 as the ghostwriter of crypt history

Familial cancer syndromes present rare insights into malignant tumor development. The molecular background of polyp formation and the cancer prone state in Peutz-Jeghers syndrome remain enigmatic to this day. Previously, we proposed that Peutz-Jeghers polyps are not pre-malignant lesions, but an epiphenomenon to the malignant condition. However, Peutz-Jeghers polyp formation and the cancer-prone state must both be accounted for by the same molecular mechanism. Our contribution focuses on the histopathology of the characteristic Peutz-Jeghers polyp and recent research on stem cell dynamics and how these concepts relate to Peutz-Jeghers polyposis. We discuss a protracted clonal evolution scenario in Peutz-Jeghers syndrome due to a germline LKB1 mutation. Peutz-Jeghers polyp formation and malignant transformation are separately mediated through the same molecular mechanism played out on different timescales. Thus, a single mechanism accounts for the development of benign Peutz-Jeghers polyps and for malignant transformation in Peutz-Jeghers syndrome.

Gastrointestinal polyps and cancer in Peutz-Jeghers syndrome: clinical aspects

The two main problems in the management of the gastrointestinal tract in patients with Peutz-Jeghers syndrome (PJS) are the long term cancer risk and managing polyp related complications, such as intussusception and bleeding. In this article we will focus mainly on the clinical management of these problems. We will highlight some of the controversies regarding gastrointestinal PJS polyps, cancer development and cancer risk. We will review the available literature, particularly focusing on clinical data, to provide insights into these controversies. We describe guidelines for the surveillance and management of gastrointestinal polyps in PJS and review the data behind current recommendations.

Chemoprevention in patients with genetic risk of colorectal cancers

A number of genetic syndromes are known to convey a high risk of colorectal cancer. Current standards of medical practice for these patients involve genetic testing followed by screening and surgical procedures. Pharmaceutical therapies for any of these syndromes are limited in number and are generally not approved by any regulatory body for applications in these genetic groups. This review discusses advances in mechanistic understanding of the disease processes leading to the development of promising pharmaceutical therapies. Clinical trials of potential chemotherapeutic agents must focus on the reduction of disease-related events, including cancer and cancer-related mortality, in patients with genetic syndromes.

Inhibition of cyclooxygenase-2 causes regression of gastric adenomas in trefoil factor 1 deficient mice

Cyclooxygenase-2 (Cox-2) expression is a marker of reduced survival in gastric cancer patients, and inhibition of Cox-2 suppresses gastrointestinal carcinogenesis in experimental animal models. To investigate the role of Cox-2 in gastric carcinogenesis in vivo, we utilized trefoil factor 1 (Tff1) deficient mice, which model the neoplastic process of the stomach by developing gastric adenomas with full penetrance. These tumors express Cox-2 protein and mRNA, and we have now investigated the effects of genetic deletion of the mouse Cox-2 gene [also known as prostaglandin-endoperoxide synthase 2 (Ptgs2)] and a Cox-2 selective drug celecoxib. Our results show that genetic deletion of Cox-2 in the Tff1 deleted background resulted in reduced adenoma size and ulceration with a chronic inflammatory reaction at the site of the adenoma. To characterize the effect of Cox-2 inhibition in more detail, mice that had already developed an adenoma were fed with celecoxib for 8-14 weeks, which resulted in disruption of the adenoma that ranged from superficial erosion to deep ulcerated destruction accompanied with chronic inflammation. Importantly, mice fed with celecoxib for 16 weeks, followed by control food for 9 weeks, redeveloped a complete adenoma with no detectable inflammatory process. Finally, we determined the identity of the Cox-2 expressing cells and found them to be fibroblasts. Our results show that inhibition of Cox-2 is sufficient to reversibly disrupt gastric adenomas in mice.

Hereditary colon cancer syndromes

Colon cancer is associated with a family history in up to 25% of cases. As many as 5% are associated with an established hereditary syndrome, demonstrating the profound influence of inheritable genetic mechanisms in the development of this disease. These syndromes confer a diverse spectrum of risk, age of presentation, endoscopic and histological findings, extracolonic manifestations, and modes of inheritance. As the molecular characteristics of these disorders become better described, enhanced genotype-phenotype correlations may offer a more targeted approach to diagnosis, screening, and surveillance. While the strategies for diagnosis and management of familial adenomatous polyposis (FAP) and Lynch syndrome are more established, the approach to newly recognized syndromes such as MUTYH-associated polyposis (MAP) and hyperplastic polyposis syndromes continues to evolve. Effective cancer prevention in affected individuals and at-risk family members first requires timely recognition of these hereditary colon cancer syndromes followed by integration of genetic testing and clinical examinations.

Inherited Syndromes Predisposing to Inflammation and GI Cancer

Cancers arising within the gastrointestinal (GI) tract are commonly associated with an immune component at their inception and later in their maintenance. While many of the immune factors and immune cell types surrounding these lesions have been highlighted, the underlying pre-dispositions in immunesupported carcinogenesis are not well characterised. Inherited Mendelian GI disorders such as polyposis syndromes, while classically due to germline mutations in non-immune genes, commonly demonstrate alterations in key immune and inflammatory genes. In some cases immune based therapies have been shown to provide at least some benefit in animal models of these syndromes. The advent of genome wide association studies has begun to powerfully examine the genetic nature of complex non-Mendelian GI diseases highlighting polymorphisms within immune related genes and their potential to provide the niche in which GI cancers may originate. Here in the role in which Mendelian and non-Mendelian genetics of immune related factors supporting GI malignancy will be presented and discussed.

Advances in understanding the biological roles of HBx

Hepatitis B virus (HBV) is the leading cause of liver cancer. Globally, there are over 350 million individuals chronically infected with HBV, and approximately 25% of these individuals will develop hepatocellular carcinoma (HCC). HBV is the prototype virus of the hepadnavirus family. The genome of HBV is circular and contains four open reading frames (ORFs). The HBx protein encoded by the X region of HBV is a multifunctional regulatory protein that possesses a wide transactivation activity and plays critical roles in regulating intracellular signal transduction, viral replication and transcription, cell proliferation and apoptosis, protein degradation, and heredity stability of hepatocytes. Due to its important roles in the development of chronic liver diseases, the research on the HBx protein has become a hot topic in recent years. In this paper, we will summarize the latest advances in understanding the biological roles of the HBx protein.

Impaired gastric gland differentiation in Peutz-Jeghers syndrome

Gastrointestinal hamartomatous polyps in the Peutz-Jeghers cancer predisposition syndrome and its mouse model (Lkb1(+/-)) are presumed to contain all cell types native to the site of their occurrence. This study aimed to explore the pathogenesis of Peutz-Jeghers syndrome polyposis by characterizing cell types and differentiation of the epithelium of gastric polyps and predisposed mucosa. Both antral and fundic polyps were characterized by a deficit of pepsinogen C-expressing differentiated gland cells (antral gland, mucopeptic, and chief cells); in large fundic polyps, parietal cells were also absent. Gland cell loss was associated with an increase in precursor neck cells, an expansion of the proliferative zone, and an increase in smooth muscle alpha-actin expressing myofibroblasts in the polyp stroma. Lack of pepsinogen C-positive gland cells identified incipient polyps, and even the unaffected mucosa of young predisposed mice displayed an increase in pepsinogen C negative glands (25%; P = 0045). In addition, in small intestinal polyps, gland cell differentiation was defective, with the absence of Paneth cells. There were no signs of metaplastic differentiation in any of the tissues studied, and both the gastric and small intestinal defects were seen in Lkb1(+/-) mice, as well as polyps from patients with Peutz-Jeghers syndrome. These results identify impaired epithelial differentiation as the earliest pathological sign likely to contribute to tumorigenesis in individuals with inherited Lkb1 mutations.

Conditional deletion of the Lkb1 gene in the mouse mammary gland induces tumour formation

Heterozygous germline mutations in the LKB1 (STK11) gene cause Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder characterized by hamartomatous polyposis of the gastrointestinal tract and an increased risk of colorectal, breast, and other cancers. To model the role of LKB1 mutation in mammary tumourigenesis, we have used a conditional gene targeting strategy to generate a mouse in which exons encoding the kinase domain of Lkb1 were deleted specifically in the mammary gland. Mammary gland tumours developed in these mice with a latency of 46-85 weeks and occurred in the thoracic or inguinal glands. These tumours were grade 2 invasive ductal carcinomas or solid papillary carcinomas with histological features similar to those described in breast cancers arising in patients with PJS. This mouse model of Lkb1 deficiency provides a potentially useful tool to investigate the role of Lkb1 in tumourigenesis and to guide the development of therapeutic approaches.

Peutz-Jeghers syndrome: Diagnostic and therapeutic approach

Peutz-Jeghers syndrome (PJS) is an inherited, autosomal dominant disorder distinguished by hamartomatous polyps in the gastrointestinal tract and pigmented mucocutaneous lesions. Prevalence of PJS is estimated from 1 in 8300 to 1 in 280 000 individuals. PJS predisposes sufferers to various malignancies (gastrointestinal, pancreatic, lung, breast, uterine, ovarian and testicular tumors). Bleeding, obstruction and intussusception are common complications in patients with PJS. Double balloon enteroscopy (DBE) allows examination and treatment of the small bowel. Polypectomy using DBE may obviate the need for repeated urgent operations and small bowel resection that leads to short bowel syndrome. Prophylaxis and polypectomy of the entire small bowel is the gold standard in PJS patients. Intraoperative enteroscopy (IOE) was the only possibility for endoscopic treatment of patients with PJS before the DBE era. Both DBE and IOE facilitate exploration and treatment of the small intestine. DBE is less invasive and more convenient for the patient. Both procedures are generally safe and useful. An overall recommendation for PJS patients includes not only gastrointestinal multiple polyp resolution, but also regular lifelong cancer screening (colonoscopy, upper endoscopy, computed tomography, magnetic resonance imaging or ultrasound of the pancreas, chest X-ray, mammography and pelvic examination with ultrasound in women, and testicular examination in men). Although the incidence of PJS is low, it is important for clinicians to recognize these disorders to prevent morbidity and mortality in these patients, and to perform presymptomatic testing in the first-degree relatives of PJS patients.

Oral rapamycin reduces tumour burden and vascularization in Lkb1(+/-) mice

Patients with Peutz-Jeghers syndrome (PJS) are affected by hamartomatous intestinal polyposis and increased risk of cancers in multiple organs caused by germline mutations in the tumour suppressor gene LKB1. Murine models that recapitulate aspects of PJS have been created. Here we examine the therapeutic effect of rapamycin, a macrolide with anti-tumourigenic and anti-angiogenic properties, in reducing tumour incidence in a large cohort of Lkb1(+/-) mice. To study the influence of early intervention, the animals were dosed with rapamycin from the age of 8 weeks, well before the onset of polyposis. These mice continued to receive the drug, which was well tolerated, throughout their lives. At sacrifice, we observed a reduction in gastric tumour burden in the rapamycin-treated mice (p = 0.0001) compared with age- and sex-matched controls. Treated animals also have a lower number of polyps per mouse than controls. In the polyps from the treated mice, phosphorylation of ribosomal p70 S6 kinase was maintained, while the phosphorylation of AKT at serine-473 was elevated, suggesting that mTORC1 function is maintained at this dosage. Despite this, a significant reduction in microvessel density was seen in polyps from the rapamycin-treated mice compared to those from the control mice (p = 5 x 10(-5)), suggesting that the anti-angiogenic effect of rapamycin played a role in polyp reduction. Overall, we demonstrated that prolonged oral administration of rapamycin from an early age is effective in lowering tumour burden in the Lkb1(+/-) mice without evident side effects.

LKB1 and AMPK family signaling: the intimate link between cell polarity and energy metabolism

Research on the LKB1 tumor suppressor protein mutated in cancer-prone Peutz-Jeghers patients has continued at a feverish pace following exciting developments linking energy metabolism and cancer development. This review summarizes the current state of research on the LKB1 tumor suppressor. The weight of the evidence currently indicates an evolutionary conserved role for the protein in the regulation of various aspects of cellular polarity and energy metabolism. We focus on studies examining the concept that both cellular polarity and energy metabolism are regulated through the conserved LKB1-AMPK signal transduction pathway. Recent studies from a variety of model organisms have given new insight into the mechanism of polyp development and cancer formation in Peutz-Jeghers patients and the role of LKB1 mutation in sporadic tumorigenesis. Conditional LKB1 mouse models have outlined a tissue-dependent context for pathway activation and suggest that LKB1 may affect different AMPK isoforms independently. Elucidation of the molecular mechanism responsible for Peutz-Jeghers syndrome will undoubtedly reveal important insight into cancer development in the larger population.

Potent cell growth inhibitory effects in hepatitis B virus X protein positive hepatocellular carcinoma cells by the selective cyclooxygenase-2 inhibitor celecoxib

Hepatitis B virus (HBV) X protein (HBx) and cyclooxygenase-2 (COX-2) are all playing roles in hepatocellular carcinoma (HCC), but the reversing effects of COX-2 inhibitors on the neoplastic features caused by HBx protein is still unclear. To further evaluate the therapeutic potential of celecoxib on HBx mediated transformation, HCC cells transfected with HBx gene were treated with COX-2 selective inhibitor, celecoxib. The amount the main metabolite of COX-2, prostaglandin E2 (PGE2), was determined by using high sensitivity ELISA. Electron microscope and flow cytometry was used to analyze cell apoptosis and cell cycle distribution. RT-PCR and Western blot were used to identify the molecules involved in celecoxib induced cell apoptosis. The results showed that celecoxib inhibited cell growth more significantly and also induced more cell apoptosis in HBx over-expression cells than in control cells. Celecoxib could selectively inhibited COX-2 expression and PGE2 production. Celecoxib also inhibited p(473Ser)Akt, raf and p53 expression, and induced apoptosis by release of cytochrome c and activation of caspase 9, 3, and 6, which were more remarkably in HBx positive cells than in control cells. These results suggest that celecoxib had potent cell growth inhibitory effects on HBx positive HCC cells mainly through inducing more cell apoptosis, and these findings provide a new insight into the anticancer effects of celecoxib against HBx related HCC.

Chemopreventive efficacy of rapamycin on Peutz-Jeghers syndrome in a mouse model

Germline mutations in LKB1 cause Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder with a predisposition to gastrointestinal polyposis and cancer. Hyperactivation of mTOR-signaling has been associated with PJS. We previously reported that rapamycin treatment of Lkb1(+/-) mice after the onset of polyposis reduced the polyp burden. Here we evaluated the preventive efficacy of rapamycin on Peutz-Jeghers polyposis. We found that rapamycin treatment of Lkb1(+/-) mice initiated before the onset of polyposis in Lkb1(+/-) mice led to a dramatic reduction in both polyp burden and polyp size and this reduction was associated with decreased phosphorylation levels of S6 and 4EBP1. Together, these findings support the use of rapamycin as an option for chemoprevention and treatment of PJS.

LKB1; linking cell structure and tumor suppression

Germ line mutations in the LKB1 tumor suppressor gene are associated with the Peutz-Jeghers polyposis and cancer syndrome. Somatic mutations in Lkb1 are observed in sporadic pulmonary, pancreatic and biliary cancers and melanomas. The LKB1 serine-threonine kinase functionally and biochemically links control of cellular structure and energy utilization through activation of the AMPK family of kinases. Lkb1 regulates cell polarity through downstream kinases including AMPKs, MARKs and BRSKs, and nutrient utilization and cellular metabolism through the AMPK-mTOR pathway. LKB1 has been shown to affect normal chromosomal segregation, TGF-beta signaling in the mesenchyme and WNT and p53 activity. Although each of the LKB1-dependent processes and downstream pathways have been individually delineated through work across a range of experimental systems, how they relate to Lkb1's role as a tumor suppressor remains to be fully explored and elucidated. The recent development of mouse cancer models harboring engineered mutations in Lkb1 have offered insights into how LKB1 may be functioning to restrain tumorigenesis and how its role as a master regulator of polarity and metabolism could contribute to its tumor suppressor function.

Molecular insights into Peutz-Jeghers syndrome: two probands with a germline mutation of LKB1

LKB1 encodes a serine/threonine protein kinase that is defective in patients with Peutz-Jeghers syndrome (PJS), a hereditary disorder characterized by gastrointestinal hamartomatous polyposis and an increased risk of cancer development. Although a tentative molecular classification of PJS patients was recently made according to their LKB1 mutation status, it is difficult to clarify the genotype-phenotype relationship because of the rarity and genetic heterogeneity of this disease. Here we report on two probands with PJS whose intestinal hamartomatous polyposis was treated by laparoscopyassisted polypectomy. Direct sequencing analyses revealed a nonsense mutation at codon 240 in exon 5 in one patient, and a mutation at a splicing donor site in intron 5 in the other patient. No additional somatic mutations were detected in the resected hamartomas in either case. Immunohistochemical analysis revealed an elevated expression of cyclooxygenase-2, and almost complete loss of LKB1 expression in the polyps, suggesting that a biallelic inactivation of the LKB1 gene was responsible for the hamartoma formation. Methylation-specific polymerase chain reaction analysis revealed no hypermethylation of the LKB1 promoter. Mutation analysis is useful in making a precise diagnosis of PJS in candidate probands, and may in the near future provide valuable information for predicting cancer risk based on genotype-phenotype correlations.

Intussusception in the adult: an unsuspected case of Peutz-Jeghers syndrome with review of the literature

Peutz-Jeghers syndrome is an uncommon genetic defect in the signal pathways of growth. The incidence has most recently been estimated to be in the range of 1 per 120,000 live births [1]. It is characterized by hamartomas throughout the gastrointestinal tract, mucocutaneous melanotic spots and increased predisposition to malignancy. The infrequent presentation of this syndrome in most practice combined with some less well-known diagnostic features may contribute to a misdiagnosis. Further, understanding of the genetic defect leading to the phenotypic syndrome and the future implications of this defect continue to evolve. Therefore we present a review in the setting of a case of misdiagnosed Peutz-Jeghers syndrome to portray illuminating features of the syndrome and review the literature.

Role of LKB1 in lung cancer development

Three phenotypically related genetic syndromes and their lesions (LKB1, PTEN, and TSC1/2) are identified as frequently altered in lung cancer. LKB1, a kinase inactivated in 30% of lung cancers, is discussed in this review. Loss of LKB1 regulation often coincident with KRAS activation allows for unchecked growth and the metabolic capacity to accommodate the proliferation.

Suppression of Peutz-Jeghers polyposis by targeting mammalian target of rapamycin signaling

PURPOSE

Peutz-Jeghers syndrome (PJS) is a unique disorder characterized by the development of hamartomas in the gastrointestinal tract as well as increased risks for variety of malignancies. Germ-line mutations of LKB1 cause PJS. We have generated Lkb1+/- mice, which model human PJS. Rapamycin and its analogues are promising preventive and therapeutic agents that specifically inhibit signaling from mammalian target of rapamycin (mTOR). Hyperactivation of mTOR signaling has been associated with PJS. The objective of the study is to investigate the efficacy of mTOR inhibition in suppressing Peutz-Jeghers polyposis in Lkb1+/- mice.

EXPERIMENTAL DESIGN

We initiated a trial of rapamycin in Lkb1+/- mice at 9 months of age (after the onset of polyposis) at the dose of 2 mg/kg/d for a 2-month period. We assessed the efficacy of rapamycin by measuring polyp sizes and tumor burden. To examine the effect of rapamycin on mTOR signaling, phosphorylation levels of S6 were evaluated by immunostaining.

RESULTS

We observed a significant decrease in mean tumor burden (Student's t test, P = 0.023) as well as total tumor burden in rapamycin-treated group compared with control group. Comparison of the polyp size observed in both rapamycin-treated and control groups showed that rapamycin efficiently decreased the tumor burden of large polyps (> 8 mm). This inhibition of rapamycin was associated with a decrease in phosphorylated S6 levels in the polyps.

CONCLUSIONS

Rapamycin effectively suppresses Peutz-Jeghers polyposis in a mouse model, suggesting that rapamycin or its analogues may represent a new targeted therapy for the treatment of PJS.

An anti-adenoma antibody, Adnab-9, may reflect the risk for neoplastic progression in familial hamartomatous polyposis syndromes

Patients with the hamartomatous polyposis Peutz-Jeghers and familial juvenile polyposis syndromes are predisposed to colorectal cancer but lack early genetic alterations found in adenomatous premalignant lesions. We studied hamartomatous polyps for the expression of an early preneoplastic colorectal neoplasia risk marker also found in familial adenomatous polyposis patients. Retrospective, genetic, and hospital archival tissue immunohistochemistry using Adnab-9, a premalignant marker often found in Paneth-like cells (PCs), was performed on sections of polyps from eight patients with Peutz-Jeghers syndrome, eight patients with familial juvenile polyposis, and 36 hyperplastic polyp control sections. Anti-alpha-defensin 5 (AD5), a universal PC marker, was also used to label a subgroup of sections. Hamartomatous polyposis patients also underwent specific genetic analysis. Eighty-nine percent of Peutz-Jeghers syndrome polyps labeled with Adnab-9 compared with 63% for AD5; 88% of familial juvenile polyposis sections also labeled with Adnab-9. Of the 36 hyperplastic polyp sections, only four (11%) labeled with Adnab-9 and one (3%) with AD5. Adnab-9 labeling of PCs in the epithelial elements of hamartomatous colonic lesions of hereditary hamartomatous syndrome patients reflects the predisposition to colorectal cancer, further justifying early intervention strategies.

Celecoxib induced tumor cell radiosensitization by inhibiting radiation induced nuclear EGFR transport and DNA-repair: a COX-2 independent mechanism

PURPOSE

The purpose of the study was to elucidate the molecular mechanisms mediating radiosensitization of human tumor cells by the selective cyclooxygenase (COX)-2 inhibitor celecoxib.

METHODS AND MATERIALS

Experiments were performed using bronchial carcinoma cells A549, transformed fibroblasts HH4dd, the FaDu head-and-neck tumor cells, the colon carcinoma cells HCT116, and normal fibroblasts HSF7. Effects of celecoxib treatment were assessed by clonogenic cell survival, Western analysis, and quantification of residual DNA damage by gammaH(2)AX foci assay.

RESULTS

Celecoxib treatment resulted in a pronounced radiosensitization of A549, HCT116, and HSF7 cells, whereas FaDu and HH4dd cells were not radiosensitized. The observed radiosensitization could neither be correlated with basal COX-2 expression pattern nor with basal production of prostaglandin E2, but was depended on the ability of celecoxib to inhibit basal and radiation-induced nuclear transport of epidermal growth factor receptor (EGFR). The nuclear EGFR transport was strongly inhibited in A549-, HSF7-, and COX-2-deficient HCT116 cells, which were radiosensitized, but not in FaDu and HH4dd cells, which resisted celecoxib-induced radiosensitization. Celecoxib inhibited radiation-induced DNA-PK activation in A549, HSF7, and HCT116 cells, but not in FaDu and HH4dd cells. Consequentially, celecoxib increased residual gammaH2AX foci after irradiation, demonstrating that inhibition of DNA repair has occurred in responsive A549, HCT116, and HSF7 cells only.

CONCLUSIONS

Celecoxib enhanced radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance, a signaling that was independent of COX-2 activity. This novel observation may have therapeutic implications such that COX-2 inhibitors may improve therapeutic efficacy of radiation even in patients whose tumor radioresistance is not dependent on COX-2.

Hamartomatous polyposis syndromes

The hamartomatous polyposis syndromes are a heterogeneous group of disorders that share an autosomal-dominant pattern of inheritance and are characterized by hamartomatous polyps of the gastrointestinal tract. These syndromes include juvenile polyposis syndrome, Peutz-Jeghers syndrome and the PTEN hamartoma tumor syndrome. The frequency and location of the polyps vary considerably among syndromes, as does the affected patient's predisposition to the development of gastrointestinal and other malignancies. Although the syndromes are uncommon, it is important for the clinician to recognize these disorders because they are associated with considerable morbidity and mortality, not only from malignancy but also from nonmalignant manifestations such as bleeding, intussusception, and bowel obstruction. Each hamartomatous polyposis syndrome has its own distinctive organ-specific manifestations and each requires a different surveillance strategy, which makes accurate diagnosis crucial for appropriate patient management. The availability of clinical genetic testing for these disorders means that appropriate recognition allows for timely referral for cancer genetic counseling, and often allows for predicative testing in at-risk family members. Promisingly, an understanding of the molecular pathogenesis of these disorders offers insights into the mechanisms underlying the development of sporadic malignancy, and enables rational selection of targeted therapies that warrant further investigation.

Genodermatoses with malignant potential

PURPOSE OF REVIEW

The delineation of syndromes carrying a predisposition to malignancy has led to great insights into the molecular biology of malignancy. Many such syndromes have cutaneous findings which can precede the development of neoplasia. Early recognition of the cutaneous stigmata of the genodermatoses with malignant potential can lead to early diagnosis and initiation of proper screening and treatment when indicated.

RECENT FINDINGS

This article reviews 'classic' genodermatoses with malignant potential and highlights recent recommendations for screening and treatment. Additionally more recently delineated syndromes and their cutaneous findings are discussed.

SUMMARY

Certain inherited syndromes with a risk of neoplasia exhibit characteristic cutaneous findings. Recognition of these findings by the astute practitioner can lead to early intervention which can impact the course of these rare diseases.

[Family study in Peutz-Jeghers syndrome]

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant hereditary disease characterized by mucocutaneous pigmentation, gastrointestinal hamartomatous polyposis and an increased risk for the development of gastrointestinal and extra-gastrointestinal malignancies.

AIM AND METHODS

Five generations of two PJS families (21-21 patients) were analyzed to summarize the clinical appearance of the disorder by interview, physical examination, laboratory and imaging studies.

RESULTS

Phenotypic variability was observed in PJS both in and between families. In family "A" 13 people were diagnosed as being affected, all of them had melanin spots at birth and the first presenting clinical symptom was colicky abdominal pain (median age 12 years, range: 2-35) resulting in 14 laparotomies in 9 of the affected persons. 4/13 patients died from small-bowel ileus (median age 7 years, range 2-31), 2/13 from GI cancer (median age 54 years). In family "B" 7 patients were documented as being affected. The first features were also abdominal cramps (at age 22). The main causes of death were gynaecological (1/5) and GI malignancies (4/5) at advanced age, no one died in ileus.

CONCLUSIONS

The results based on the analysis of the two families suggest that PJS is not a benign disease. It is difficult to predict the outcome of the disorder regarding the variable expression and incomplete penetrance. Therefore we emphasize the importance of checking the pedigree, finding out the leading symptom in the family; hemoccult test and routine lab studies should be carried out at every affected individual. If clinical signs and symptoms are present we recommend to perform the complete diagnostic protocol and a yearly follow-up by a gastroenterologist familiar with PJS focusing on the leading symptoms.

Cyclooxygenase-2 expression in polyps from a patient with juvenile polyposis syndrome with mutant BMPR1A

OBJECTIVES

Cyclooxygenase-2 (COX-2) expression is increased in colorectal cancers and has been reported to be upregulated in Peutz-Jeghers polyps. To determine whether germline and somatic loss of BMPR1A in polyps from a patient with juvenile polyposis syndrome have altered COX-2 expression, we characterized a patient with juvenile polyposis syndrome for BMPR1A germline mutations and examined the polyps for BMPR1A expression and COX-2 expression.

PATIENTS AND METHODS

DNA analysis for BMPR1A was performed on a patient with juvenile polyposis syndrome. Multiple polypectomies were performed, and several polyps showed adenomatous change. Genomic DNA was extracted from polyp material for loss of heterozygosity (LOH) analyses with microsatellite markers. Immunohistochemistry was performed on sections using antibodies for BMPR1A and COX-2.

RESULTS

The kindred possessed a germline BMPR1A missense mutation. In polyp domains containing cystic and adenomatous epithelium, no LOH was observed using markers near the BMPR1A locus. Immunostaining indicated decreased expression of phospho-SMAD1 (pSMAD1), functionally downstream of the mutant BMPR1A receptor in the cystic epithelium, with further reduction in adenomatous portions within the polyp. COX-2 protein, normally not expressed in the colon, was present and increased in polyp epithelium.

CONCLUSIONS

Decreased expression of pSMAD1 in the cystic epithelium with further reduction in the adenomatous area, and increase in COX-2 expression within polyps from the BMPR1A heterozygote, suggest a potential mechanism for adenomatous pathogenesis in these hamartomatous polyps. This may imply that COX-2 inhibitors could be a means for chemoprevention in this syndrome.