STK11 genotyping and cancer risk in Peutz-Jeghers syndrome

[Prepubertal gynecomastia at the debut of hereditary tumors predisposition syndrome (clinical case reports)]

Peutz-Jeghers Syndrome (Peutz-Jeghers Syndrome, PJS) refers to syndromes of hereditary tumor predisposition and is caused by pathological variants of the STK11 gene, leading to a defect in the synthesis of serine/threonine kinase 11 protein, which acts as a tumor suppressor.Clinical symptoms of the syndrome are combination of hamartomatous polyposis of the gastrointestinal tract and specific skin-mucosal hyperpigmentation. Also, this disease is characterized by a high risk of developing gastrointestinal and extra-intestinal tumors, including benign or malignant tumors of the reproductive system.One of the first signs of the disease in male patients may be prepubertal gynecomastia associated with large-cell calcifying Sertoli cells tumors expressing aromatase. In contrast to from pubertal gynecomastia, prepubertal is extremely rare, and it is often based on pathological causes. Early diagnosis of patients with pre-pubertal gynecomastia, including Peitz-Jaegers syndrome, defines the tactics of gynecomastia management and protocols for monitoring the development of other components of the disease in the future.This article describes two patients with pre-pubertal gynecomastia and Peitz-Jaegers syndrome with different molecular genetic defects: in one case associated with duplication of the STK11 gene site, in the other - with microdeletion of the short arm of chromosome 19 containing this gene.

STK11 Causative Variants and Copy Number Variations Identified in Thai Patients With Peutz-Jeghers Syndrome

Introduction Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder caused by germline mutations in the serine-threonine kinase 11 (STK11) tumor suppressor gene. This syndrome is characterized by hamartomatous gastrointestinal polyps, mucocutaneous melanin pigmentation, and a higher risk of developing various cancers. Methods We summarized the clinical and molecular characteristics of five unrelated Thai patients with PJS. Denaturing high-performance liquid chromatography (DHPLC) screening, coupled with direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA), were applied for the molecular analysis of STK11. Results A total of four STK11 pathogenic changeswere identified in the five PJS patients, including two frameshift variants (a novel c.199dup, p.Leu67ProfsTer96 and a known c.834_835del, p.Cys278TrpfsTer6) and two types of copy number variations (CNV), exon 1 deletion and exons 2-3 deletion. Among reported STK11 exonic deletions, exon 1 and exons 2-3 deletions were found to be the two most commonly deleted exons. Conclusion All identified STK11 mutations were null mutations that were associated with more severe PJS phenotypes and cancers. This study broadens the phenotypic and mutational spectrum of STK11 in PJS.

Serine/Threonine Kinase 11 Plays a Canonical Role in Malignant Progression of KRAS -Mutant and GNAS -Wild-Type Intraductal Papillary Mucinous Neoplasms of the Pancreas

OBJECTIVE

We aimed to elucidate the clinicopathobiological significance of Serine/Threonine Kinase 11 (STK11) in pancreatic intraductal papillary mucinous neoplasms (IPMNs).

BACKGROUND

STK11 is a tumor suppressor involved in certain IPMNs; however, its significance is not well known.

METHODS

In 184 IPMNs without Peutz-Jeghers syndrome, we analyzed expression of STK11 and phosphorylated-AMPKa in all cases, and p16, p53, SMAD4, and β-catenin in 140 cases by immunohistochemistry; and we analyzed mutations in 37 genes, including whole coding exons of STK11, CDKN2A, TP53, and SMAD4, and hotspots of KRAS, BRAF, and GNAS in 64 cases by targeted sequencing. KRAS and GNAS were additionally analyzed in 86 STK11-normal IPMNs using digital-PCR.

RESULTS

Consistent loss or reduction of STK11 expression was observed in 26 of 184 (14%) IPMNs. These STK11-aberrant IPMNs were 17 of 45 (38%) pancreatobiliary, 8 of 27 (30%) oncocytic, 1 of 54 (2%) gastric, and 0 of 58 (0%) intestinal subtypes ( P = 8.5E-11), and 20 of 66 (30%) invasive, 6 of 74 (8%) high-grade, and 0 of 44 (0%) low-grade ( P = 3.9E-06). Sixteen somatic STK11 mutations (5 frameshift, 6 nonsense, 1 splicing, and 4 missense) were detected in 15/26 STK11-aberrant IPMNs ( P = 4.1E-06). All STK11-aberrantIPMNs were GNAS -wild-type and 96% of them were KRAS or BRAF -mutant.Morphologically, STK11-aberrant IPMNs presented "fern-like" arborizing papillae with thin fibrovascular core. Phosphorylated-AMPKa was down-regulated in STK11-aberrant IPMNs (92%, P = 6.8E-11). Patients with STK11-aberrant IPMNs showed poorer survival than patients with STK11-normal IPMNs ( P = 3.6E-04 overall; P = 6.1E-04 disease-free).

CONCLUSION

STK11 may play a canonical role in malignant progression and poor survival of patients with IPMNs. Aberrant STK11-driven phosphorylated AMPK downregulation may provide therapeutic opportunities with mTOR inhibitors/AMPK activators.

Identification of high-risk germline variants for the development of pancreatic cancer: Common characteristics and potential guidance to screening guidelines

Pancreatic cancer (PC) is a product of a variety of environmental and genetic factors. Recent work has highlighted the influence of hereditary syndromes on pancreatic cancer incidence. The purpose of this review is to identify the high-risk syndromes, common variants, and risks associated with PC. The study also elucidates common characteristics of patients with these mutations, which is used to recommend potential changes to current screening protocols for greater screening efficacy. We analyzed 8 syndromes and their respective variants: Hereditary Breast and Ovarian Cancer (BRCA1/2), Familial Atypical Multiple Mole Melanoma Syndrome (CDKN2A), Peutz-Jeghers Syndrome (STK11), Lynch Syndrome (PMS2, MLH1, MSH2, MSH6, EPCAM), Ataxia Telangiectasia (ATM), Li-Fraumeni Syndrome (TP53), Fanconi Anemia (PALB2), and Hereditary Pancreatitis (PRSS1, SPINK1, CFTR). Of 587 studies evaluated, 79 studies fit into our inclusion criteria. Information from each study was analyzed to draw conclusions on these variants as well as their association with pancreatic cancer. Information from this review is intended to improve precision medicine and improve criteria for screening.

High risk and early onset of cancer in Chinese patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominant inherited disorder associated with a predisposition to a variety of cancers. Previous studies that have evaluated the cancer spectrum and risk of this rare disease have primarily been based on small data sets or heterogeneous cohorts from different countries. Here, we report the results of a large homogeneous cohort of Chinese PJS patients who were followed prospectively from 2006 to July 2021, and clinical data before 2006 were retrospectively collected. A total of 412 PJS patients (56.55% males) from 208 families were enrolled, contributing 12,798 person-years of follow-up. A total of 113 cancers were diagnosed in 109 patients (26.46%). The median age at the first cancer diagnosis was 40 years. In particular, patients born after the 1980s were diagnosed with cancer at an earlier median age of 30.5 years. The cumulative cancer risk was sharply increased to 30.9% at age 40 years; this high cancer risk age was 10 years earlier than that reported in previous Western studies, and increased to 76.2% at an age of 60 years. The most common cancer was gastrointestinal (GI) cancer (64.6%), in which colorectal cancer constituted a significantly larger proportional distribution (32.74%), when compared with previous investigations (11.1%−20.83%). There was some evidence that overrepresentation point variants in domain XI of STK11 may be associated with GI cancers. Furthermore, the incidences of gynecological and lung cancers were second only to that of GI cancer in this cohort. These results may provide novel insight for justifying surveillance to detect cancers at an earlier phase to improve clinical outcomes. Furthermore, the potential STK11 genotype-phenotype association could be the basis for future genetic counseling.

STK11 (LKB1) missense somatic mutant isoforms promote tumor growth, motility and inflammation

Elucidating the contribution of somatic mutations to cancer is essential for personalized medicine. STK11 (LKB1) appears to be inactivated in human cancer. However, somatic missense mutations also occur, and the role/s of these alterations to this disease remain unknown. Here, we investigated the contribution of four missense LKB1 somatic mutations in tumor biology. Three out of the four mutants lost their tumor suppressor capabilities and showed deficient kinase activity. The remaining mutant retained the enzymatic activity of wild type LKB1, but induced increased cell motility. Mechanistically, LKB1 mutants resulted in differential gene expression of genes encoding vesicle trafficking regulating molecules, adhesion molecules and cytokines. The differentially regulated genes correlated with protein networks identified through comparative secretome analysis. Notably, three mutant isoforms promoted tumor growth, and one induced inflammation-like features together with dysregulated levels of cytokines. These findings uncover oncogenic roles of LKB1 somatic mutations, and will aid in further understanding their contributions to cancer development and progression.

Paula Granado-Martínez, Sara Ortega, Elena González-Sánchez et al. report a functional analysis of four cancer-associated mutant isoforms of the gene STK11 using cell-based and animal models. They find the mutant isoforms no longer show tumor suppressor activity, promote tumor growth, and affect the regulation of cytokines and genes involved in vesicle trafficking.

Novel germline STK11 variants and breast cancer phenotype identified in an Indian cohort of Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) caused by germline STK11 variants is a rare autosomal dominant cancer predisposition syndrome characterized by multiple gastrointestinal (GI) hamartomatous polyps, mucocutaneous pigmentation and a high inherited risk of developing GI, breast and other cancers. Despite GI and breast being the two most common PJS-associated cancer sites, the immunohistochemical (IHC) and molecular features of these tumors in carriers of STK11 variant is not known. Detailed phenotyping including tumor IHC and its correlation with comprehensive STK11 genotyping by full gene sequencing followed by large genomic rearrangement analysis was performed in an Indian PJS cohort. A total of 4 distinct STK11 pathogenic or likely pathogenic variants were identified in 10 PJS cases from 7 of the 19 families tested-in 4/5 classical PJS families and 3/14 suspected PJS families. The pathogenic STK11 variant identified was novel in 3/7 families. In addition, four distinct, likely benign variants identified in seven families were also novel. All of the four breast cancer cases in families with STK11 pathogenic variant were estrogen receptor (ER)-positive and Her2-negative. Several novel STK11 variants identified in this Indian PJS cohort highlight the need to study PJS in different populations across the world. This is the first report showing ER positivity in breast cancer in carriers of STK11 variants and needs confirmation in a larger pooled cohort of PJS associated breast cancers. This could help establish the role of chemoprevention or prophylactic oophorectomy in female carriers of STK11 pathogenic variants.

An exploration of genotype-phenotype link between Peutz-Jeghers syndrome and STK11: a review

Peutz-Jeghers Syndrome (PJS) is an autosomal dominant hereditary polyposis syndrome. Clinical features include hamartomatous polyps, mucocutaneous pigmentation and an increased predisposition towards developing malignancy. Variants in STK11, a tumour suppressor gene, located on Chromosome 19, predispose to PJS. Peutz-Jeghers Syndrome is associated with increased rates of malignancy, particularly gastrointestinal. However, PJS is also associated with increased gynaecological, testicular and thyroid papillary malignancy. Truncating variants in STK11 are thought to predispose to a more severe phenotype. Phenotype severity is based on earlier onset of gastrointestinal pathology arising from the polyps, such as intussusception or earlier onset malignancy. Missense variants are generally considered less severe than truncating variants. There remain a large number of variants of undetermined significance. Studies have attempted to correlate the location of variants with impact on protein structure and overall severity of the PJS phenotype. The results from these cohort studies have consistently found a non-random distribution of variants. Nevertheless, a consensus on phenotype severity based on variant location is yet to be established. A centralised database that collates all known variants would facilitate the interpretation of these variants, best under the governance of an international disease-specific organisation (InSiGHT). In particular, it could help explore the significance of variants based on their type or location. Understanding the genotype-phenotype link between STK11 variants and PJS could allow more personalised care for PJS patients and their families via appropriate risk stratification and personalised and targeted cancer screening.

[Hereditary predisposition to breast cancer (1): genetics]

The main objective of oncogenetics is to characterize a subpopulation of patients at high risk of cancer development at an early age in order to provide specific recommendations for an optimized follow-up and care path. Oncogenetic counselling helps to assess individual risk from a family history. By a family approach of formal genetics, the key issue is to identify families with a strong aggregation of cancers, and, in particular, suggesting a specific syndrome of inherited predisposition to cancer. This approach can lead to the proposal of germline genetic testing in search of causal mutations. As up to know, the search for a constitutional mutation in the BRCA genes has led to the identification of a causal deleterious mutation in less than 10% of index-cases analyzed. It is therefore important to evaluate the impact of new genes in the current panorama of inherited predisposition to breast and ovarian cancer.

STK11 gene analysis reveals a significant number of splice mutations in Chinese PJS patients

BACKGROUND

The combination of direct sequencing and multiple ligation-dependent probe amplification (MLPA) has resulted in an 80% detection rate of serine/threonine kinase 11 (STK11) gene mutations in Peutz-Jeghers syndrome (PJS); however, this rate varies in different ethnicities.

AIMS

To test the efficacy of the combination in Chinese patients with PJS.

METHODS

PJS probands visiting our center during one year were enrolled. Sanger sequencing and MLPA were used to detect STK11 mutations. Associations between the occurrence of severe complications and risk factors were analyzed statistically.

RESULTS

We identified 47 PJS probands. Among them, 34 received an STK11 mutation test, revealing 23 point mutations and 2 exonic deletions. Nine of the mutations were splicing errors, reflecting a significantly higher proportion (p < 0.05). Laparotomy history existed for 33 of the probands, and seven families had a history of cancer. Statistical analysis revealed no associations between the occurrence of severe complications or cancers and risk factors.

CONCLUSION

The strategy achieved a high detection rate in Chinese people, validating its effectiveness. This cohort comprised a significantly higher proportion of splicing errors, reflecting the unique genetic characteristics Chinese people. No specific genotype-phenotype relationship was noted, while the wide usage of enteroscopy would benefit PJS surveillance.

Close and regular surveillance is key to prevent severe complications for Peutz-Jeghers syndrome patients without gastrointestinal polyps: case report of a novel STK11 mutation (c.471_472delCT) in a Chinese girl

Background

Peutz-Jeghers syndrome (PJS) is a Mendelian disease characterized by gastrointestinal hamartomas, mucocutaneous pigmentation (MP), and increased cancer risk. Serine/threonine kinase 11 (STK11) is the only validated causative gene in PJS. Clinical observation reveals MP and intussusception in childhood are more frequent and severe than in adults.

Case presentation

We report here a girl without a positive family history, who grew oral and fingertip MP at her age of 2 and got abdomen dull pain from 7 years old. Endoscopy revealed no obvious polyps in the stomach or the colon until 10 years old, when she received enteroscopy. Tens of polyps were resected during enteroscopy, and pathological examination confirmed them hamartomas. A heterozygous deletion in STK11, c.471_472delCT, was detected in the proband but not in her parents, which is not recorded in databases.

Conclusion

The mutation we reported here is a novel one and a de-novo one, so our results enlarge the spectrum of STK11. We speculate close and regular endoscopy especially enteroscopy is necessary for complication prevention when the former endoscopy discovers no polyps temporarily in a child of suspect PJS.

Whole exome sequencing identified sixty-five coding mutations in four neuroblastoma tumors

Neuroblastoma is a pediatric tumor characterized by histologic heterogeneity, and accounts for ~15% of childhood deaths from cancer. The five-year survival for patients with high-risk stage 4 disease has not improved in two decades. We used whole exome sequencing (WES) to identify mutations present in three independent high-risk stage 4 neuroblastoma tumors (COA/UAB-3, COA/UAB -6 and COA/UAB -8) and a stage 3 tumor (COA/UAB-14). Among the four tumors WES analysis identified forty-three mutations that had not been reported previously, one of which was present in two of the four tumors. WES analysis also corroborated twenty-two mutations that were reported previously. No single mutation occurred in all four tumors or in all stage 4 tumors. Three of the four tumors harbored genes with CADD scores ≥20, indicative of mutations associated with human pathologies. The average depth of coverage ranged from 39.68 to 90.27, with >99% sequences mapping to the genome. In summary, WES identified sixty-five coding mutations including forty-three mutations not reported previously in primary neuroblastoma tumors. The three stage 4 tumors contained mutations in genes encoding protein products that regulate immune function or cell adhesion and tumor cell metastasis.

Clinical manifestations and STK11 germline mutations in Taiwanese patients with Peutz-Jeghers syndrome

BACKGROUNDS

Clinical manifestations and molecular basis of Taiwanese patients with Peutz-Jeghers syndrome (PJS) were investigated to add the knowledge of phenotype and genotype of the disease.

METHODS

Based on the Pathology Data Bank and the Colorectal Cancer Register, we collected their clinical data. The entire coding sequence of the STK11 gene was amplified and analyzed by sequencing using the genomic DNA.

RESULTS

Fifteen patients diagnosed with PJS from 11 unrelated families were collected until 2015. The median age at the onset of symptoms was 19 years with intussusception as the most frequent presenting symptom. Ten patients developing 11 cancers at various anatomical sites, including two cases of sinonasal cancer, two lung cancers, two breast cancers, two rectal cancers, two gynecological cancers and one small bowel cancer. Five of the deceased patients had died of cancers. The median age of diagnosis of first cancer in the probands was 32 years. Seventy patients (7 of 10) diagnosed before age of 40. Mutations found in eight families included five novel mutations (exon 6, c.843 ins G; exon 8, c.2065 delete A; exon 8, c.G923A, nonsense; exon 6, c.748dupA; and mTOR c.5107dupA) and three previously reported mutations. The other three PJS families without detectable STK11 mutations did not develop malignancies so far.

CONCLUSION

This is the first comprehensive study of patients with Peutz-Jeghers syndrome in the Taiwanese. We have demonstrated that the phenotype of Peutz-Jeghers syndrome varies greatly among the patients. Patients with detectable STK11 mutations have very high risk of developing cancers.

Relationship between gastric polyps and Helicobacter pylori infection

AIM

To explore the relationship between the clinicopathological features of gastric polyps and the infection status of Helicobacter pylori (H. pylori).

METHODS

Data for gastric polyps detected by gastroscopy at the Endoscopy Center of Air Force General Hospital from January 2013 to December 2016 were collected, and their clinical and pathological features were analyzed. The difference in age was analyzed by t test. The distributions of age, sex, H. pylori infection status, number of polyps, and location were analyzed by χ² test.

RESULTS

In 39572 cases of endoscopic examinations, 2445 cases of gastric polyps were detected. After excluding some cases according to the inclusion criteria, a total of 1339 cases of gastric polyps were included in this study. There were 771, 559 and 9 cases of hyperplastic, fundic gland and adenomatous polyps, respectively. Multiple polyps were detected in 991 cases. Fundic gland polyps tended to affect females and have a lower positive rate of H. pylori and more multiple lesions, and involve the fundus and body of the stomach (P < 0.05). There was no significant difference in age distribution between the two groups. The positive rate of H. pylori for multiple lesions was lower than that for single lesion (P < 0.05).

CONCLUSION

Fundic gland polyps have a low H. pylori positive rate and tend to be multiple and occur in the fundus and the body of the stomach. The detection rate of fundic gland polyps increases, which may lead to a lower H. pylori positive rate in multiple polyps than in single polyp.

Duodenal cancer in a young patient with Peuts-Jeghers syndrome harboring an entire deletion of the STK11 gene

A 21-year-old woman with Peuts-Jeghers syndrome (PJS) was referred to our hospital for gastrointestinal surveillance. She had been diagnosed as having PJS from a young age based on her family history and the presence of mucocutaneous pigmentation on her lips and oral mucosa. Her mother and brother had PJS harboring an entire deletion of the STK11 gene. She had tetralogy of Fallot, atrial tachycardia, sick sinus syndrome, and mental retardation in her past history. Esophagogastroduodenoscopy identified a protruded lesion with a depressed area that occupied the lumen half-circumferentially in the duodenal second portion and also showed a 10-mm protruded lesion on the anterior wall of the lower gastric body. Colonoscopy revealed a 3-mm protruded lesion on the rectum. No polyp was found in a barium small bowel series. Biopsies were taken from the duodenal tumor and gastric and colon polyps. Histopathologically, the duodenal tumor revealed a well-differentiated tubular adenocarcinoma, whereas gastric and colon polyps showed hamartomatous polyp. Therefore, subtotal stomach-preserving pancreatoduodenectomy was performed, and subsequent histopathological examination revealed that the duodenal tumor consisted of hamartomatous polyp and a well-differentiated tubular adenocarcinoma with invasion to the muscularis propria. Immunohistochemistry revealed accumulation of nuclear p53 protein, but no accumulation of nuclear β-catenin protein. No RAS mutation was detected. Furthermore, direct sequencing of the STK11 gene in genomic DNA from peripheral blood mononuclear cells did not detect any mutation initially. However, multiplex ligation-dependent probe amplification (MLPA) analysis revealed entire deletion of STK11. These findings suggest that entire deletion of the STK11 gene caused hamartomatous polyps in the entire gastrointestinal tract and, subsequently, duodenal polyps likely gave rise to cancer through p53 mutation.

Correlation between genotype and phenotype in three families with Peutz-Jeghers Syndrome

Peutz-Jeghers syndrome (PJS) is a hereditary disorder characterized by mucocutaneous pigmentations, gastrointestinal (GI) polyposis and an increased risk of certain malignancies. Little is known about the causative genes of PJS, or their association with the clinical phenotypes of PJS. The present study reports the results of clinical and genetic analysis of three Chinese families with PJS. In addition, the medical histories and clinical manifestations of these families were compared. DNA was collected from the blood samples of patients with PJS and controls. Serine/threonine kinase 11 (STK11), olfactory receptor family 4 subfamily C member 45 (OR4C45) and zonadhesin (ZAN) were amplified by polymerase chain reaction, and analyzed by sequencing and cloning. Two PJS-affected members of one family had a de novo single base deletion (NM_000455.4:c.842delC) in the STK11 gene, and their clinical presentations reflected the quantity of mutant STK11 copies in a dose-dependent manner. No pathogenic variants of OR4C45 or ZAN were found in the patients with PJS, although a new single nucleotide polymorphism (NM_003386.2:c.5768delG) of ZAN was identified. The results of the current study identified that a STK11 mutation dose-dependent genotype-phenotype relationship exists in patients with PJS. In addition, an early onset and high severity of oral pigmentations in PJS was indicative of serious GI phenotypes. These findings may aid the diagnosis and treatment of PJS.

[Rare hereditary syndromes associated with polyposis and the development of malignant tumors]

Familial adenomatous polyposis (FAP) and Peutz-Jeghers syndrome are genetic diseases characterized by gastrointestinal polyps, extraintestinal manifestations, and autosomal dominant inheritance. The carriers of these diseases from early childhood are at risk for neoplasias at different sites, which are symptomatic at various ages.

AIM

to study the clinical organ-specific manifestations in patients with FAP and Peutz-Jeghers, genetics update and possibilities of diagnosis, monitoring, and treatment of these diseases.

MATERIAL AND METHODS

The authors give the results of their examination and follow-up of children with FAP and Peutz-Jeghers hamartoma-polypous syndrome. In addition, current data from PubMed, Medline (including reviews, original articles and case reports) were used.

RESULTS

The main clinical organ-specific signs of multiple tumors in FAP and Peutz-Jeghers syndrome are shown. Data on the assessment of a risk for malignant tumors at various sites in the affected patients and their family members at different ages are provided. Each of these syndromes has a dissimilar genetic foundation. FAP is caused by the germline mutations in the APC gene, Peutz-Jeghers syndrome is by the STK11 gene, which predispose individuals to specifically associated neoplasias and require different follow-up strategies. Information on a phenotype-genotype correlation may serve as a reference point for the possible severity and various manifestations of a disease. An update on the molecular pathogenesis of these diseases is considered.

CONCLUSION

Molecular genetic testing of the genes associated with FAP and Peutz-Jeghers syndromes makes it possible to timely recognize family members at high risk, to plan therapeutic strategy and to affect the course of a disease. The joint participation of pediatricians, proctologists, oncologists, morphologists, geneticists, and molecular biologists is essential to timely recognize the carriers of the syndromes and a better prognosis in these patients.

Unraveling the Deleterious Effects of Cancer-Driven STK11 Mutants Through Conformational Sampling Approach

Tumor suppressor gene, STK11, encodes for serine-threonine kinase, which has a critical role in regulating cell growth and apoptosis. Mutations of the same lead to the inactivation of STK11, which eventually causes different types of cancer. In this study, we focused on identifying those driver mutations through analyzing structural variations of mutants, viz., D194N, E199K, L160P, and Y49D. Native and the mutants were analyzed to determine their geometrical deviations such as root-mean-square deviation, root-mean-square fluctuation, radius of gyration, potential energy, and solvent-accessible surface area using conformational sampling technique. Additionally, the global minimized structure of native and mutants was further analyzed to compute their intramolecular interactions and distribution of secondary structure. Subsequently, simulated thermal denaturation and docking studies were performed to determine their structural variations, which in turn alter the formation of active complex that comprises STK11, STRAD, and MO25. The deleterious effect of the mutants would result in a comparative loss of enzyme function due to variations in their binding energy pertaining to spatial conformation and flexibility. Hence, the structural variations in binding energy exhibited by the mutants, viz., D194N, E199K, L160P, and Y49D, to that of the native, consequently lead to pathogenesis.

Energy sensing and cancer: LKB1 function and lessons learnt from Peutz-Jeghers syndrome

We describe in this review increasing evidence that loss of LKB1 kinase in Peutz-Jeghers syndrome (PJS) derails the existing natural balance between cell survival and tumour growth suppression. LKB1 deletion can plunge cells into an energy/oxidative stress-induced crisis which leads to the activation of alternative and often carcinogenic pathways to maintain cellular energy levels. It therefore appears that although LKB1 deficiency can suppress oncogenic transformation in the short term, it can ultimately lead to more progressed and malignant phenotypes by driving abnormal cell differentiation, genomic instability and increased tumour heterogeneity.

Update on our investigation of malignant tumors associated with Peutz-Jeghers syndrome in Japan

PURPOSE

To investigate the recent incidence of malignant tumors associated with Peutz-Jeghers syndrome (PJS) in Japan to clarify if there are any differences in malignant tumor risk and the spectrum of malignancies by reviewing the literature on this subject.

METHODS

We reviewed PJS cases reported in 1115 papers in Japan between January, 1989 and December, 2014.

RESULTS

Malignant tumors were identified in 186 of the total 583 PJS cases from 523 evaluable studies. The estimated cumulative risk of a malignant tumor was 83.0 % at 70 years of age. Compared with a previous study, on a collective 91 cases reported up until 1988 in Japan, the reported proportion of gastrointestinal malignancies decreased, from 82.4 to 48.3 %, whereas that of gynecological malignancies increased, from 8.8 to 34.3 % (P < 0.01). Moreover, breast cancers were occasionally reported (4.8 %), even though none were reported in the previous study. Adenocarcinoma of the uterine cervix was the most common malignant tumor (46.8 %) among women with PJS.

CONCLUSIONS

The increased number of reports of cervical adenocarcinoma in women with PJS is the prominent trend in Japan, and a subject of concern among gynecologists. The risk of breast cancer seems to be increasing, but confirmation of this trend will require further investigation.

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.

Clinical characteristics and STK11 gene mutations in Chinese children with Peutz-Jeghers syndrome

Background

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disease characterized by gastrointestinal hamartomatous polyps and mucocutaneous melanin spots. Germline mutation of the serine/threonine kinase 11 (STK11) gene are responsible for PJS. In this study, we investigated the clinical characteristics and molecular basis of the disease in Chinese children with PJS.

Methods

Thirteen children diagnosed with PJS in our hospital were enrolled in this study from 2011 to 2015, and their clinical data on polyp characteristics, intussusceptions events, family histories, etc. were described. Genomic DNA was extracted from whole-blood samples from each subject, and the entire coding sequence of the STK11 gene was amplified by polymerase chain reaction and analyzed by direct sequencing.

Results

The median age at the onset of symptoms was 2 years and 4 months. To date, these children have undergone 40 endoscopy screenings, 17 laparotomies and 9 intussusceptions. Polyps were found in the stomach, duodenum, small bowel, colon and rectum, with large polyps found in 7 children. Mutations were found in eleven children, including seven novel mutations (c.481het_dupA, c.943_944het_delCCinsG, c.397het_delG, c.862 + 1G > G/A, c.348_349het_delGT, and c.803_804het_delGGinsC and c.121_139de l19insTT) and four previously reported mutations (c.658C > C/T, c.890G > G/A, c.1062 C > C/G, and c.290 + 1G > G/A). One PJS patient did not have any STK11 mutations.

Conclusions

The polyps caused significant clinical consequences in children with PJS, and mutations of the STK11 gene are generally the cause of PJS in Chinese children. This study expands the spectrum of known STK11 gene mutations.

Polycystic ovary syndrome (PCOS) with melanocytic mucosal macules: the role of STK11 gene polymorphisms in PCOS and Peutz-Jeghers syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a complex genetic disorder that is the most common endocrinopathy that affects women.

OBSERVATIONS

We report two individuals with PCOS with a genetic polymorphism in serine threonine kinase 11 (STK11). Both these individuals developed mucosal pigmentation suggesting Peutz-Jeghers syndrome (PJS), which is associated with mutations in STK11. Both individuals showed some improvement in their metabolic and endocrine dysregulation with therapies commonly used for PCOS. However, they continued to show progression of mucosa pigmentation.

CONCLUSIONS

This is the first report of clinical overlap in individuals with PCOS and PJS, even though some individuals with PCOS show a polymorphism in STK11, which is the gene mutated in PJS. The importance of this clinical association is not clear but may be significant because of the association of STK11 dysregulation and the development of internal tumors.

[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.

Growing recognition of the role for rare missense substitutions in breast cancer susceptibility

Most cancer susceptibility genes function as tumor suppressors; accordingly, the focus of mutation screening in breast cancer families has been to identify protein-truncating mutations. However, it is now clear that, for some breast cancer susceptibility genes, a significant proportion of the burden of disease comes from rare missense substitutions. Among genes that have been extensively evaluated, BRCA1, BRCA2, PALB2 and BRIP1 stand as examples where the majority of mutations lead to protein truncation;TP53 provides a counter example, where the majority of pathogenic variants are missense substitutions. In ATM and CHEK2, missense substitutions are probably equally or more important in terms of their frequency and attributable risk. Therefore, ongoing efforts to identify new susceptibility genes should not ignore missense variation.

STK11 domain XI mutations: candidate genetic drivers leading to the development of dysplastic polyps in Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is a rare hereditary disorder resulting from mutations in serine/threonine kinase 11 (STK11) and characterized by gastrointestinal (GI) hamartomatous polyps, mucocutaneous pigmentation, and an increased risk for specific cancers. Little is known about the genetic implications of specific STK11 mutations with regard to their role in dysplastic and malignant transformation of GI polyps. Peripheral blood genomic DNA samples from 116 Chinese PJS patients from 52 unrelated families were investigated for STK11 mutations. Genotype-phenotype correlations were investigated. The mutation detection rate was 67.3% (51.9% point mutations, 15.4% large deletions). Fourteen out of the 25 point mutations identified were novel. Nearly one-third of all mutations, 8/27 (29.6%), were in exon 7, the shortest out of the nine exons. Strikingly, mutations affecting protein kinase domain XI, encoded in part by exon 7, correlated with a 90% (9/10) incidence of GI polyp dysplasia. In contrast, only two out of 17 (11.8%) nondomain XI mutations were linked to polyp dysplasia (P = 0.0001). The extent of the association between dysplasia and the development of GI-related cancers is currently unknown but our results highlight a novel STK11 genotype-phenotype association as the basis for future genetic counseling and basic research studies.

Exome sequencing revealed novel germline mutations in Chinese Peutz-Jeghers syndrome patients

BACKGROUND AND AIMS

Peutz-Jeghers Syndrome (PJS) is an autosomal dominant disorder which predisposes to the development of various cancers. Germline mutation in the serine/threonine kinase 11 gene (STK11) is known as one of the major causes of PJS. However, a notable proportion of PJS samples do not carry any mutation in STK11, suggesting possible genetic heterogeneity in the disease and the existence of other causative variants.

METHODS AND RESULTS

In order to identify other germline variants in the coding regions of the genome that are associated with PJS, we performed exome sequencing in three Chinese individuals with PJS and identified 16 common germline variants (12 protein-coding including STK11, 4 in pre-microRNAs). We further validated protein-coding variants in six PJS individuals (three with wild-type STK11) and predicted the functional impact. As result, we found that 7 coding variants are likely to have functional impacts. Especially, we identified 2 new germline variants which are represented in all six PJS samples and are independent of STK11 mutation.

CONCLUSIONS

Our study provided an exomic view of PJS. The germline variants identified in our analysis may help to resolve the complex genetic background of the disease and thus lead to the discovery of novel causative variants of PJS.

Analysis of STK11 gene variant in five Chinese patients with Peutz-Jeghers syndrome

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder characterized by gastrointestinal hamartomatous polyps and mucocutaneous pigmentation. Germline mutation of a serine/threonine kinase 11(STK11) gene has been identified as a cause of PJS. In this study, we investigated the molecular basis of five Chinese PJS patients.

METHODS

Blood samples were collected from five unrelated Chinese PJS patients and their parents. The entire coding region of the STK11 gene was amplified by polymerase chain reaction and analyzed by direct sequencing.

RESULTS

Three different frameshift mutations (c.519insTGTG, c.792_793insT, and c.334_335insC), all of which would cause truncation of the gene product, were found in three patients. One missense mutation (p.Ser307Thr) and one 3bp deletion mutation (c.228-230del CGT) were identified in the remaining two patients. All of the five investigated patients carried de novo mutations.

CONCLUSIONS

The results support that mutation of the LKB1 gene is a cause of PJS, and expand the spectrum of the STK11 gene mutations.

High Resolution Melting analysis as a rapid and efficient method of screening for small mutations in the STK11 gene in patients with Peutz-Jeghers syndrome

Background

Peutz-Jeghers syndrome (PJS) is a rare hereditary syndrome characterized by the occurrence of hamartomatous polyps in the gastrointestinal tract, mucocutaneous pigmentation and increased risk of cancer in multiple internal organs. Depending on the studied population, its incidence has been estimated to range from 1:200 000 even up to 1:50 000 births. Being an autosomal disease, PJS is caused in most cases by mutations in the STK11 gene.

Methods

The majority of causative DNA changes identified in patients with PJS are small mutations and, therefore, developing a method of their detection is a key aspect in the advancement of genetic diagnostics of PJS patients. We designed 13 pairs of primers, which amplify at the same temperature and enable examination of all coding exons of the STK11 gene by the HRM analysis.

Results

In our group of 41 families with PJS small mutations of the STK11 gene were detected in 22 families (54%). In the remaining cases all of the coding exons were sequenced. However, this has not allowed to detect any additional mutations.

Conclusions

The developed methodology is a rapid and cost-effective screening tool for small mutations in PJS patients and makes it possible to detect all the STK11 gene sequence changes occurring in this group.

Minimal deviation adenocarcinoma of the cervix and tumorlets of sex-cord stromal tumor with annular tubules of the ovary in Peutz-Jeghers syndrome

We report 2 cases of minimal deviation adenocarcinoma of the cervix and tumorlets of sex cord tumor with annular tubules (SCTATs) of the ovaries, accompanied by Peutz-Jeghers syndrome. Case 1 is a 36-year-old woman and case 2 is a 35-year-old woman. Grossly, the cervix of both cases showed markedly barrel shaped enlargement with an infiltrating tumor. Microscopically, well-differentiated atypical glands were infiltrating into the entire thickness of the cervix. The ovarian masses in case 1 were diagnosed as metastatic carcinoma in mucinous cystadenoma with tumorlets of SCTATs of the ovaries. Multiple scattered tumorlets of SCTATs were also found in the ovary of case 2. By direct DNA sequencing analysis, a frame shift mutation of the STK11/LKB1 gene was identified in case 1. Case 1 represented the more aggressive clinical course, and although the patient received additional combined chemo-radiation therapy, she expired 1 year later. In general, mutation of the STK11/LKB1 gene is associated with poor clinical outcome in malignant tumors accompanied by Peutz-Jeghers syndrome.

One novel deletion and one splicing mutation of the LKB1 gene in two Chinese patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an uncommon autosomal dominant inherited disease, characterized by the occurrence of gastrointestinal hamartomatous polyps and pigmentation of the lips, buccal mucosa, and digits. Patients with PJS have a significant risk for developing tumors in multiple organs. Germline mutation of the LKB1 gene, which encodes a serine/threonine kinase that acts as a tumor suppressor, has been identified as a cause of PJS. The current study included two Chinese PJS probands and their available family members, as well as 200 unrelated healthy controls for comparison. Genomic DNA was extracted from the peripheral blood of these subjects. The nine coding exons and flanking introns of the LKB1 gene in the two probands and their family members were amplified by polymerase chain reaction (PCR) and then directly sequenced. Mutations identified in the patients were checked in the 200 healthy controls by PCR and denaturing high-performance liquid chromatography. Total RNA was extracted from the patient who was found to have a dubious splice site mutation and his available family members. Reverse transcription PCR was performed to identify the abnormal splicing caused by the splice site mutation. Two types of mutations were detected in the two PJS families. One type was a previously unreported 30-base-pair deletion in exon 4, and the other was an intron mutation that affected splicing. None of the 200 controls had either of these two types of mutations. The results provide support that mutation of the LKB1 gene is a cause of PJS, and expand the spectrum of LKB1 gene mutations.

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.

A novel mutation in STK11 gene is associated with Peutz-Jeghers syndrome in Chinese patients

BACKGROUND

Peutz-Jeghers syndrome (PJS) is caused by mutations in the tumor suppressor gene, STK11, and is characterized by gastrointestinal hamartomas, melanin spots on the lips, and an increased risk of developing cancer.

METHODS

Blood samples were collected from two unrelated Chinese PJS families totaling 20 individuals (9 male and 11 females), including 6 PJS patients. The entire coding region of the STK11 gene was amplified by polymerase chain reaction and analyzed by direct sequencing.

RESULTS

A novel mutation, c.904C > T, in exon 7 was identified in both families. A C > T substitution changed codon 302 from CAG (glutamine) to TAG (stop), truncating the STK11 protein, thus leading to the partial loss of the kinase domain and complete loss of the α-helix C-terminus. Furthermore, one PJS patient from each family was diagnosed with a visceral cancer, a colon cancer and a liver cancer respectively.

CONCLUSION

We predict that this novel mutation, p.Q302X, is most likely responsible for development of the PJS phenotype and may even contribute to malignancy.

Peutz-Jeghers syndrome: intriguing suggestion of gastrointestinal cancer prevention from surveillance

BACKGROUND

Peutz-Jeghers syndrome is characterized by GI polyps and mucocutaneous pigmentation and carries an increased risk of GI cancer. GI polyps may bleed or cause intussusception. Luminal GI surveillance is recommended, but there are few data detailing outcomes from GI surveillance in Peutz-Jeghers syndrome.

OBJECTIVE

This study aimed to assess outcomes from GI surveillance in patients with Peutz-Jeghers syndrome.

DESIGN

This study is a retrospective review, using hospital and registry notes and endoscopy and histology reports.

SETTING

The investigation was conducted at a tertiary referral center.

PATIENTS

All patients with Peutz-Jeghers syndrome who were followed up at St Mark's hospital were included.

MAIN OUTCOME MEASURES

The primary outcomes measured were surveillance procedures performed, complications, and long-term outcomes.

RESULTS

Sixty-three patients from 48 pedigrees were included; the median age when patients were first seen was 20 years (range, 3-59). Only baseline investigations were performed in 12 patients. The remaining patients were followed up for 683 patient years, a median of 10 years (range, 2-41). Seven hundred seventy-six procedures were performed to assess the GI tract. These led to 5 double-balloon enteroscopies, 1 push enteroscopy, and 71 surgical procedures. Of the surgical procedures, 20 were performed as a result of baseline investigations, 12 arose from investigations of symptoms, and 39 were due to surveillance of asymptomatic patients. No emergency surgical interventions were performed. No luminal GI cancers were diagnosed. Of the 2461 polypectomies performed, 6 polyps contained atypia or dysplasia. Six complications arose from endoscopy or surgical intervention, requiring 5 laparotomies to manage these complications.

CONCLUSION

GI surveillance in Peutz-Jeghers syndrome is relatively safe and avoids the need for emergency surgery for small-bowel polyps. The lack of GI cancers may reflect that surveillance and polypectomy have prevented cancer from developing, although the detection of neoplasia or dysplasia is uncommon.

High risk of cancer in Peutz-Jeghers syndrome

AIM: To assess cancer risk in patients with Peutz-Jeghers syndrome (PJS) and to develop a surveillance recommendation.

METHODS: A systematic PubMed search was performed to analyze related data of cancer in patients with PJS described in 20 cohort studies.

RESULTS: The cohort studies included 3 302 patients in total, and 573 (17.35%) of them developed 619 cases of cancer, including 368 (60.23%) cases of gastrointestinal and 243 (39.77%) cases of non-gastrointestinal cancers. The most common malignancy was colorectal cancer, followed by small bowel, breast, gastroesophageal, gynecological, pancreatic, and lung cancers. The age range of the high incidence rate of cancer was 11-70 years old, and seemed younger among Chinese patients than that in other countries. The lifetime relative risks for any cancer ranged from 9.9 to 18, for gastrointestinal cancer was 13 to 50.5, breast cancer 13.9 to 20.3, and gynecological cancer was 20.3 compared with the general population. Obviously, the age-related cumulative risks are increasing. The STK11/LKB1 mutation did not significantly influence cancer risk (P > 0.05).

CONCLUSION: Patients with PJS have markedly increased relative and absolute risk for gastrointestinal and non-gastrointestinal cancers. In order to improve the outcome for PJS patients, it is very important to strengthen cancer surveillance and closer follow-up in an early phase.

Identification of a Novel de Novo STK11 Mutation in a Chinese Child with Peutz-Jeghers Syndrome

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder characterized by gastrointestinal polyposis and mucocutaneous pigmentation. PJS patients have an increased risk of cancer in multiple locations. Germ-line mutations in the STK11 gene have been found to be responsible for most PJS cases. DNA samples were obtained from a Chinese child with PJS, his clinically unaffected parents and 50 unrelated normal individuals, and the exons and flanking intronic sequences of the STK11 gene were analysed by polymerase chain reaction and direct sequencing. A novel de novo mutation (c.698_699insG; F234LfsX3) was identified in exon 5 of STK11, that resulted in a translational frameshift leading to termination at codon 236. This mutation was not found in the parents or unrelated individuals. These results enlarge the genotypic spectrum of STK11, particularly with regard to early onset, as observed in the present sporadic PJS case. This study may have important future implications for precise genotype-phenotype correlation research.

Peutz-Jeghers syndrome: a study of long-term surgical morbidity and causes of mortality

Patients with Peutz-Jeghers syndrome (PJS) require lifelong multidisciplinary care for gastrointestinal polyposis and increased risk of cancer. Their long-term morbidities and causes of mortality are unknown. Patients with a definitive diagnosis of PJS (n = 54) were retrospectively reviewed for disease course and outcome. Operative details, pathology and complications were noted for those treated surgically (n = 33). Median follow-up was 7.0 years (interquartile range: 2-20). Two malignancies were found intra-operatively (duodenal and rectal adenocarcinoma). In the long-term, 42% underwent additional operations; 1 patient developed short bowel syndrome, while another, chronic partial bowel obstruction and pain. Twenty-one additional cancers were treated in 19 patients: gynecologic (11), lung (3), and prostate (2) being the most common. 16 patients (30%) were deceased, at a median age of 51 years. The cause of death was unknown in 4 patients, but was due exclusively to malignancies in all other patients, most commonly due to metastatic gynecologic cancer (5). The overall survival of PJS patients was significantly shorter than the expected survival of an age-and gender-matched reference population (P < 0.001). Given the morbidities associated with repeated operations and the risk for cancer-related mortality in the long-term, efforts should focus on minimizing the need for surgical intervention and optimizing cancer detection, treatment and prevention.

High cancer risk in Peutz-Jeghers syndrome: a systematic review and surveillance recommendations

OBJECTIVES

Peutz-Jeghers syndrome (PJS) is an autosomal dominant inherited disorder associated with increased cancer risk. Surveillance and patient management are, however, hampered by a wide range in cancer risk estimates. We therefore performed a systematic review to assess cancer risks in PJS patients and used these data to develop a surveillance recommendation.

METHODS

A systematic PubMed search was performed up to February 2009, and all original articles dealing with PJS patients with confirmed cancer diagnoses were included. Data involving cancer frequencies, mean ages at cancer diagnosis, relative risks (RRs), and cumulative risks were collected.

RESULTS

Twenty-one original articles, 20 cohort studies, and one meta-analysis fulfilled the inclusion criteria. The cohort studies showed some overlap in the patient population and included a total of 1,644 patients; 349 of them developed 384 malignancies at an average age of 42 years. The most common malignancy was colorectal cancer, followed by breast, small bowel, gastric, and pancreatic cancers. The reported lifetime risk for any cancer varied between 37 and 93%, with RRs ranging from 9.9 to 18 in comparison with the general population. Age-related cumulative risks were given for any cancer and gastrointestinal, gynecological, colorectal, pancreatic, and lung cancers.

CONCLUSIONS

PJS patients are markedly at risk for several malignancies, in particular gastrointestinal cancers and breast cancer. On the basis of these elevated risks, a surveillance recommendation is developed to detect malignancies in an early phase and to remove polyps that may be premalignant and may cause complications, so as to improve the outcome.

Medical management update: Peutz Jeghers syndrome

Peutz Jeghers syndrome (PJS) is an autosomal dominant disease characterized by hamartomatous polyposis and distinct mucocutaneous pigmentation. PJS is associated with an increased risk for several cancers and other complications such as small intestine intussusception, short bowel syndrome, and anemia. Medical management mainly consists of treatment of the polyps and surveillance. This medical management update will review clinical concepts, therapeutic advances, and emphasize features of PJS important to the oral health care provider.

Truncating mutations in Peutz-Jeghers syndrome are associated with more polyps, surgical interventions and cancers

BACKGROUND AND GOALS

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant polyposis syndrome caused by STK11 germline mutations. PJS is associated with an increased risk of cancer. In our cohort, clinical and phenotypic parameters were correlated with genotypic findings and patients were prospectively followed by surveillance.

STUDY

Thirty-one patients treated between 2000 and 2006, were evaluated. STK11 genotyping was performed and phenotypes of patients with truncating (TM) and nontruncating mutations (NTM) were compared.

RESULTS

Median age at first symptoms was 11 years and complications occurred before the age of ten in 42% of patients. STK11 mutations were detected in 16 of 22 families (12 TM; four NTM). Patients with TM had more surgical gastrointestinal (GI) interventions (p = 0.021), and female patients in the TM group had an increased risk of undergoing gynecological surgery (p = 0.016). Also, there was a trend towards a higher polyp count (p = 0.11) and earlier age at first polypectomy (p = 0.13) in the TM group. Ten carcinomas were detected in six patients resulting in a cancer risk of 65% up to the age of 65 years. Patients with TM tended to develop more cancers (p = 0.10). Importantly, our surveillance strategy used detected 50% of cancers (n = 5) at an early potentially curable stage.

CONCLUSIONS

Our study shows that almost half of PJ patients have complications early in life independent of mutational status. Patients with TM require more surgical GI interventions and tend to develop more polyps and cancers. Furthermore, close surveillance detects early stage cancers in patients. We propose that surveillance should be started as early as 8 years in all patients to avoid complications. Moreover, patients with TM may benefit from surveillance at shorter intervals.

Novel mutations in the STK11 gene in Thai patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS), a rare autosomal dominant inherited disorder, is characterized by hamartomatous gastrointestinal polyps and mucocutaneous pigmentation. Patients with this syndrome have a predisposition to a variety of cancers in multiple organs. Mutations in the serine/threonine kinase 11 (STK11) gene have been identified as a major cause of PJS. Here we present the clinical and molecular findings of two unrelated Thai individuals with PJS. Mutation analysis by Polymerase Chain Reaction-sequencing of the entire coding region of STK11 revealed two potentially pathogenic mutations. One harbored a single nucleotide deletion (c.182delG) in exon 1 resulting in a frameshift leading to premature termination at codon 63 (p.Gly61AlafsX63). The other carried an in-frame 9-base-pair (bp) deletion in exon 7, c.907_915del9 (p.Ile303_Gln305del). Both deletions were de novo and have never been previously described. This study has expanded the genotypic spectrum of the STK11 gene.

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.

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.

A novel de novo mutation in the serine-threonine kinase STK11 gene in a Korean patient with Peutz-Jeghers syndrome

Background

Peutz-Jeghers syndrome (PJS) is an unusual autosomal dominant disorder characterized by mucocutaneous pigmentation and multiple gastrointestinal hamartomatous polyps. Patients with PJS are at an increased risk of developing multi-organ cancer, most frequently those involving the gastrointestinal tract. Germline mutation of the STK11 gene, which encodes a serine-threonine kinase, is responsible for PJS.

Methods

Using DNA samples obtained from the patient and his family members, we sequenced nine exons and flanking intron regions of the STK11 gene using polymerase chain reaction (PCR) and direct sequencing.

Results

Sequencing of the STK11 gene in the proband of the family revealed a novel 1-base pair deletion of guanine (G) in exon 6 (c.826delG; Gly276AlafsX11). This mutation resulted in a premature termination at codon 286, predicting a partial loss of the kinase domain and complete loss of the C-terminal domain. We did not observe this mutation in both parents of the PJS patient. Therefore, it is considered a novel de novo mutation.

Conclusion

The results presented herein enlarge the spectrum of mutations of the STK11 gene by identifying a novel de novo mutation in a PJS patient and further support the hypothesis that STK11 mutations are disease-causing mutations for PJS with or without a positive family history.