Aberrant intestinal stem cell lineage dynamics in Peutz-Jeghers syndrome and familial adenomatous polyposis consistent with protracted clonal evolution in the crypt.

OBJECTIVE: Genetic predisposition to cancer in Peutz-Jeghers syndrome (PJS) and the role of germline serine-threonine kinase (LKB1) mutations are poorly understood. The authors studied the effect of germline LKB1 mutations on intestinal stem cell dynamics in unaffected flat PJS mucosa. Recent research has documented that the intestinal crypt houses multiple equipotent stem cell lineages. Lineages continuously compete through random drifts, while somatically inherited methylation patterns record clonal diversity. DESIGN: To study the effect of germline LKB1 mutations on clonal expansion, the authors performed quantitative analyses of cardiac-specific homeobox methylation pattern diversity in crypts isolated from unaffected colonic mucosa obtained from archival PJS patient material. The authors compared methylation density and methylation pattern diversity in patients with PJS to those in patients with familial adenomatous polyposis and age-matched controls. RESULTS: The percentage of total methylation is comparable between groups, but the number of unique methylation patterns is significantly increased for patients with familial adenomatous polyposis and patients with PJS compared to control subjects. CONCLUSIONS: Monoallelic LKB1 loss is not silent and provokes a protracted clonal evolution in the crypt. The increased methylation pattern diversity observed in unaffected PJS mucosa predicts that premalignant lesions will arise at an accelerated pace compared to the general population.

Differential requirements for STRAD in LKB1-dependent functions in C. elegans.

The protein kinase LKB1 is a crucial regulator of cell growth/proliferation and cell polarity and is the causative gene in the cancer-predisposing disease Peutz-Jeghers syndrome (PJS). The activity of LKB1 is greatly enhanced following its association with the Ste20-like adapter protein STRAD. Unlike LKB1 however, mutations in STRAD have not been identified in PJS patients and thus, the key tumour suppressive role(s) of LKB1 might be STRAD independent. Here, we report that Caenorhabditis elegans strd-1/STRAD mutants recapitulate many phenotypes typical of par-4/LKB1 loss of function, showing defects during early embryonic and dauer development. Interestingly, although the growth/proliferation defects in severe par-4 and strd-1 mutant dauers are comparable, strd-1 mutant embryos do not share the polarity defects of par-4 embryos. We demonstrate that most of par-4-dependent regulation of germline stem cell (GSC) quiescence occurs through AMPK, whereby PAR-4 requires STRD-1 to phosphorylate and activate AMPK. Consistent with this, even though AMPK plays a major role in the regulation of cell proliferation, like strd-1 it does not affect embryonic polarity. Instead, we found that the PAR-4-mediated phosphorylation of polarity regulators such as PAR-1 and MEX-5 in the early embryo occurs in the absence of STRD-1. Thus, PAR-4 requires STRD-1 to phosphorylate AMPK to regulate cell growth/proliferation under reduced insulin signalling conditions, whereas PAR-4 can promote phosphorylation of key proteins, including PAR-1 and MEX-5, to specify early embryonic polarity independently of STRD-1. Our results therefore identify a key strd-1/STRAD-independent function of par-4/LKB1 in polarity establishment that is likely to be important for tumour suppression in humans.

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.

Peutz-Jeghers syndrome and management recommendations.

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disease caused by germline mutation of the serine threonine kinase 11 and characterized by hamartomatous polyps in the gastrointestinal tract and mucocutaneous melanin pigmentation. Patients with PJS are at increased risk for common and unusual types of gastrointestinal and nongastrointestinal tumors. This review analyzes currently available literature and describes the clinical characteristics of PJS, assesses the risk of malignancy in this disorder, and delineates management and surveillance recommendations for affected individuals.

Peutz-Jeghers syndrome: case reports and update on diagnosis and treatment.

OBJECTIVE: To analyze the etiology and diagnostic methods of Peutz-Jeghers syndrome (PJS) and thus establish a treatment strategy. METHODS: Clinical data from six patients with PJS were evaluated from the aspect of familial history, carcinogenesis and recurrence of polyps. RESULTS: The fathers of four and the mother of one of the six patients had PJS. The grandfather of three of the six patients had PJS. There was a history of cancer in three of the five families. Case 4 underwent two laparotomies for intussusceptions caused by recurrent polyps of the small intestine. Case 5 also had recurrent small intestinal polyps and required a laparotomy after 1 year of initial treatment. Polyps in cases 1 and 4 showed adenomatous changes and those in case 2 were associated with gastric cancer. CONCLUSIONS: Patients with PJS have a strong family history of cancer and a high incidence of recurrence of small intestinal polyps. Malignant changes of polyps may follow the hamartoma-adenoma-carcinoma sequence. Careful follow-up is mandatory for gastrointestinal tract symptoms, and other solid organs that are susceptible to malignant change.

[Sporadic and hereditary colorectal cancer. Pathogenetically different with different therapeutic indications]. / Sporadisches und hereditäres Karzinom von Kolon und Rektum. Pathogenetisch different mit unterschiedlicher Therapieindikation.

In recent years, there have been major advances regarding the understanding of the pathogenesis of sporadic and hereditary colorectal cancer on the basis of molecular research. The clinical implications of this knowledge differ for the sporadic and hereditary forms. In sporadic colorectal cancer, gene mutations occur in colorectal cells but not as germline mutations. Even though molecular data currently do not influence the clinical management of this form of colorectal cancer, promising molecular approaches exist for the assessment of prognosis, early detection, prevention, and therapy. Germline mutations are the cause of hereditary colorectal cancers, in which molecular methods have a major impact on diagnosis and therapy. Prophylactic surgery is accepted for patients with familial adenomatous polyposis (FAP), but not for patients with hereditary non-polyposis colorectal cancer (HNPCC), the second main form of hereditary colorectal cancer. Further studies will have to clarity this issue.

[Mutations of fragile histidine triad gene in Peutz-Jeghers syndrome and canceration].

BACKGROUND & OBJECTIVE: Peutz-Jeghers syndrome (PJS) is an autosomal dominantly inherited disease. Fragile histidine triad (FHIT) gene is an important tumor suppressor gene at the fragile sites region of 3p14. The authors' previous study suggested that PJS patients might have a susceptible gene at the region of 3p14.2. This study was designed to reveal the relationship between the variant of FHIT gene in PJS and its canceration. METHOD: Mutations of FHIT gene in 15 PJS patients and 20 unaffected members in 6 PJS families were determined using denaturing high-performance liquid chromatography (DHPLC), polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) and DNA sequencing techniques. RESULTS: A non-sense mutation and a frame-shift mutation were identified at codon 54(GAA to TAA) (exon 6) which led to the change of the amino acid from glutamic acid (Glu) to stop codon, and a guanine insertion at codon 62 in exon 6 resulting in a premature stop codon TGA at codon 111 in one PJS patient. A homozygous deletion and a synonymous mutation were detected in exon 8. The homozygous deletion of exon 8 in FHIT gene was found in two polyps tissues and two cancerous tissues. And in 3 sporadic cases, the patients and their mothers have the same bands of SSCP and the same elution profiles of DHPLC when exon 8 was amplified. The DNA sequencing result showed that a synonymous mutation (polymorphism) occurred at codon 98 [CAT (H)-->CAC (H)], this mutation resulted in no change of amino acid. In addition, one base substitute from A to G mutation at 5'end, +42 nucleotide in intron 6 of FHIT gene was detected in seven patients and two unaffected members. CONCLUSION: PJS patients have low frequency point mutation of FHIT gene and their cancerous tissues had homozygous deletions in FHIT gene. This study indicated that the mutations and deletions of FHIT gene in PJS may play a role in the development of PJS and their cancerations.

Skin manifestations of internal malignancy.

This article concentrates on the major signs and syndromes that are associated with internal malignancies in the geriatric population. Included are cutaneous metastases, ectopic adrenocorticotropic hormone-producing syndromes, and disorders arising from APUD cell tumors. The major paraneoplastic disorders of dermatomyositis, generalized pruritus, Bazex's syndrome, and acanthosis nigricans also are discussed. Also included are Bowen's disease of skin; arsenical toxicity; and the Peutz-Jeghers', Gardner's, and Torre's syndromes, which are indicative of systemic or organ-related carcinogens.

Genetics of Carney complex and related familial lentiginoses, and other multiple tumor syndromes.

Carney complex is a multiple endocrine neoplasia (MEN) syndrome that affects the adrenal cortex, the pituitary and thyroid glands, and the gonads. The complex is also associated with skin and mucosa pigmentation abnormalities and myxoid and other neoplasms of mesenchymal and neural crest origin. Thus, this syndrome also belongs to another group of genetic disorders, the lentiginoses (or lentigenoses), which include the Peutz-Jeghers, LEOPARD, arterial dissections and lentiginosis, and Laugier-Hunziker syndromes, Cowden disease and Ruvalcaba-Myhre-Smith (Bannayan-Zonana) syndrome and the centrofacial, benign patterned and segmental lentiginoses, all of which can be associated with a variety of developmental defects. The inheritance of Carney complex, just like that of the other MENs and the lentiginoses, is autosomal dominant. Genetic loci or genes have been identified for Carney complex, Peutz-Jeghers and Ruvalcaba-Myhre-Smith syndromes, but not for other lentiginoses. Elucidation of the molecular defects responsible for these disorders is expected to shed light on aspects of early neural crest differentiation, the regulation of pigmentation, the development of autonomous endocrine function, and endocrine and nonendocrine tumorigenesis.

Sindrome de Peutz-Jeghers: apresentacao de um caso com obstrucao intestinal / Peutz-Jeghers syndrome: a case report with intestinal obstruction

Os autores mostram um caso de Sindrome de Peutz-Jeghers, em um paciente de 24 anos, masculino, que cursava ha 7 meses, com dor abdominal em colica intermitente, acompanhada de vomitos e parada de eliminacao de gases e fezes. Procurou a emergencia do hospital, com quadro de obstrucao intestinal, pelo qual foi levado a cirurgia.