Cellular and molecular characteristics of stromal Lkb1 deficiency-induced gastrointestinal polyposis based on single-cell RNA sequencing.

Liver kinase B1 (Lkb1), encoded by serine/threonine kinase (Stk11), is a serine/threonine kinase and tumor suppressor that is strongly implicated in Peutz-Jeghers syndrome (PJS). Numerous studies have shown that mesenchymal-specific Lkb1 is sufficient for the development of PJS-like polyps in mice. However, the cellular origin and components of these Lkb1-associated polyps and underlying mechanisms remain elusive. In this study, we generated tamoxifen-inducible Lkb1flox/flox;Myh11-Cre/ERT2 and Lkb1flox/flox;PDGFRα-Cre/ERT2 mice, performed single-cell RNA sequencing (scRNA-seq) and imaging-based lineage tracing, and aimed to investigate the cellular complexity of gastrointestinal polyps associated with PJS. We found that Lkb1flox/+;Myh11-Cre/ERT2 mice developed gastrointestinal polyps starting at 9 months after tamoxifen treatment. scRNA-seq revealed aberrant stem cell-like characteristics of epithelial cells from polyp tissues of Lkb1flox/+;Myh11-Cre/ERT2 mice. The Lkb1-associated polyps were further characterized by a branching smooth muscle core, abundant extracellular matrix deposition, and high immune cell infiltration. In addition, the Spp1-Cd44 or Spp1-Itga8/Itgb1 axes were identified as important interactions among epithelial, mesenchymal, and immune compartments in Lkb1-associated polyps. These characteristics of gastrointestinal polyps were also demonstrated in another mouse model, tamoxifen-inducible Lkb1flox/flox;PDGFRα-Cre/ERT2 mice, which developed obvious gastrointestinal polyps as early as 2-3 months after tamoxifen treatment. Our findings further confirm the critical role of mesenchymal Lkb1/Stk11 in gastrointestinal polyposis and provide novel insight into the cellular complexity of Lkb1-associated polyp biology. © 2024 The Pathological Society of Great Britain and Ireland.

Changes of gut microbiota and short chain fatty acids in patients with Peutz-Jeghers syndrome.

Peutz-Jeghers Syndromeis a rare autosomal dominant genetic disease characterized by gastrointestinal hamartomatous polyps and skin and mucous membrane pigmentation. The pathogenesis of PJS remains unclear; however, it may be associated with mutations in the STK11 gene, and there is currently no effective treatment available. The gut microbiota plays an important role in maintaining intestinal homeostasis in the human body, and an increasing number of studies have reported a relationship between gut microbiota and human health and disease. However, relatively few studies have been conducted on the gut microbiota characteristics of patients with PJS. In this study, we analyzed the characteristics of the gut microbiota of 79 patients with PJS using 16 S sequencing and measured the levels of short-chain fatty acids in the intestines. The results showed dysbiosis in the gut microbiota of patients with PJS, and decreased synthesis of short-chain fatty acids. Bacteroides was positively correlated with maximum polyp length, while Agathobacter was negatively correlated with age of onset. In addition, acetic acid, propionic acid, and butyric acid were positively correlated with the age of onset but negatively correlated with the number of polyps. Furthermore, the butyric acid level was negatively correlated with the frequency of endoscopic surgeries. In contrast, we compared the gut microbiota of STK11-positive and STK11-negative patients with PJS for the first time, but 16 S sequencing analysis revealed no significant differences. Finally, we established a random forest prediction model based on the gut microbiota characteristics of patients to provide a basis for the targeted diagnosis and treatment of PJS in the future.

[A man with brown discolorations]. / Een man met bruine vlekjes.

A 58-year-old man presents with spontaneous brown discolorations of his mouth and hands. Our differential diagnosis included Peutz-Jeghers syndrome, Laugier-Hunziker syndrome or Addison's disease. There were no polyps in a previously performed colonoscopy and no other systemic symptoms. We made the diagnosis Laugier-Hunziker syndrome, a benign skin disorder that doesn't require treatment, confirmed by skin biopsy.

Clinicopathologic comparison between sporadic and syndromic Peutz-Jeghers polyps.

Peutz-Jeghers polyps (PJPs) are hamartomatous polyps that may define patients with Peutz-Jeghers syndrome (PJS), a rare inherited polyposis syndrome with high cancer risk. However, the clinical significance of 1-2 sporadic PJPs (without other PJS stigmata) regarding malignant potential and identification of new PJS probands is still unclear. We identified 112 patients with 524 histologically confirmed PJPs and categorized them based on polyp number into syndromic (n = 38) if ≥3 PJPs or diagnosed PJS, solitary (1 PJP, n = 61), and intermediate (2 PJPs, n = 13). Clinicopathologic features, including presence of dysplasia in the polyp and development of neoplasia in the patient, were compared on a per-patient and per-polyp basis. Whereas patients with solitary and intermediate PJPs were not different from each other, patients with syndromic PJPs were, in multivariate analysis, younger (P = .001) and more likely to develop neoplasia (P = .02) over a 62.6-months median follow-up than patients with sporadic PJPs. On an individual polyp basis, syndromic PJPs were more likely, in multivariate analysis, to occur in the small intestine (P < .001), but less likely to harbor metaplasia (P = .03) or dysplasia (P = .001), than sporadic PJPs. Dysplasia and metaplasia were more likely in larger PJPs, by multivariate analysis (P = .007 and P < .001, respectively). These data suggest that strict criteria for PJS (including ≥3 PJPs), as currently used, stratify patients into distinct groups with significant differences in clinicopathologic parameters, particularly regarding risk of neoplasia. However, sporadic PJPs exhibit characteristics such as dysplasia and are thus important to recognize and diagnose but perhaps as heralding only a forme fruste PJS.

[The course and clinical manifestations of Peutz-Jeghers syndrome in the Russian population].

BACKGROUND: Peutz-Jeghers syndrome (PJS) is a rare hereditary syndrome characterized by the growth of hamartomatous polyps in the gastrointestinal tract, perioral pigmentation and an increased risk of malignant neoplasms. The syndrome is caused by a pathogenic variant in the STK11 gene. AIM: To assess the clinical picture and treatment of Russian patients with PJS. MATERIALS AND METHODS: A retrospective analysis of 30 patients from 25 families with an established diagnosis of PJS who were in the Ryzikh State Scientific Center for Coloproctology from 2011 to 2021 was carried out. All patients underwent instrumental examination, including esophagogastroduodenoscopy, colonoscopy, X-ray examination of the small intestine/CT-enterography, in the absence of invaginates - video capsule endoscopy, as well as molecular genetic examination for the presence of pathogenic variants in the STK11 gene. All removed polyps were subjected to the histological examination. RESULTS: The analysis of the clinical picture allowed us to establish the following data: the first complaints in patients were noted in childhood and adolescence, while the median age was 11 [7; 19] (0.5-24) years; pathogenic variants in the STK11 gene were identified in 26 (87%) cases, among which 10 were described for the first time; during the initial examination, polyps in the small intestine were detected in all 30 (100%) patients, in the stomach - in 23/30 (77%) patients, and in the colon - in 21/30 (70%); with an age, an increase in the number of polyps in all parts of the gastrointestinal tract was noted; before the diagnosis operations were performed urgently for intestinal obstruction; after the diagnosis of PJS, when polyps were detected in the gastrointestinal tract, endoscopic polypectomies were performed; if endoscopic removal of hamartomatous polyps was impossible, patients were operated as planned; malignant diseases of the predominantly reproductive system were detected in 8/30 (27%) patients. The median age of cancer detection was 52 [31; 52] (17-59) years. CONCLUSION: Russian patients with PJS have population-specific features in the clinical picture of the course of the disease, which dictates the need to develop their own recommendations for monitoring and treatment of such patients.

[Sex cord tumors with annular tubules: About 4 cases and literature review]. / Les tumeurs des cordons sexuels à tubules annelés : à propos de 4 cas et revue de la littérature.

Sex cord tumor with annular tubules (SCTAT) is a rare ovarian tumor. It belongs to sex cord and stromal tumor of the ovary and represents less than 1% of cases. It includes two forms: the first one associated with Peuz-Jeghers syndrome and the second sporadic. We report 4 cases of SCTAT collected at the department of pathology of Salah Azaiez Institute of Tunis over the 12 last years. The age ranged from 10 to 32 years. Symptoms were non specific except for one case revealed by precocious puberty. One patient had Peutz-Jeghers syndrome associated. Tumors were unilateral. Gross findings showed often a solid tumor with yellow cut surface. Their size ranged from 0.5cm to 28cm. Their morphological features were characteristic. Immunohistochemistry showed that tumor cells expressed inhibin and claretinin. The treatment was surgical, often conservative. The diagnosis of malignancy wasn't focused on histological features, but on tumor extension, clinical course, and presence of metastases. Evolution was often favorable. We also performed a systematic review of the literature that identified 166 cases. Features of these cases were studied. We also compared these features between sporadic and syndromic forms and between benign and malignant forms. In conclusion, SCTAT is a rare tumor, usually benign. Its diagnosis is based on histological examination. There is a malignant potential especially in sporadic forms, estimated at 20%. Treatment is most often conservative, based on oophorectomy.

Feasibility and Safety of Endoscopic Ischemic Polypectomy and Clinical Outcomes in Patients with Peutz-Jeghers Syndrome (with Video).

OBJECTIVES: Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant hereditary disease with a clinical features related to gastrointestinal (GI) hamartomatous polyposis, frequently observed in the small bowel. Balloon-assisted enteroscopy (BAE) has made non-surgical treatment of GI polyps possible. Endoscopic mucosal resection (EMR) has been performed but was associated with complications and difficulties. Recently, endoscopic ischemic polypectomy (EIP) has been developed and its usefulness reported. The study evaluated the feasibility and safety of EIP and the clinical outcomes of patients with PJS. METHODS: We retrospectively collected data of consecutive patients with PJS between September 2009 and March 2021. Data regarding clinical characteristics, follow-up methods, endoscopic management, and complications were collected. EIP feasibility and safety were assessed. RESULTS: Twenty-two patients were included. The observation period was 70 months (range, 5-153). Of the 124 therapeutic endoscopy procedures performed, 68 used BAE. Of the 607 polyps treated, 329 polyps were located in the small bowel. EIP was able to treat a greater number of polyps per patient than EMR (P < 0.003), without any complications, carcinoma, or intussusception in the small bowel (P < 0.001). During the follow-up period, 3 patients developed GI cancer. CONCLUSION: Long-term follow-up in patients with PJS showed that EIP was a feasible and safe technique.

Preimplantation genetic testing in two Danish couples affected by Peutz-Jeghers syndrome.

BACKGROUND: Guidelines from the European Hereditary Tumor Group as well as The Danish National Guidelines for Peutz-Jeghers Syndrome (PJS) state that both prenatal diagnosis and preimplantation genetic testing for monogenic disorders (PGT-M) should be offered to patients with PJS. However, only a few cases resulting in viable pregnancies have been published. OBJECTIVE: We present two cases of PJS patients going through PGT-M for PJS. We highlight the awareness of this possibility and discuss the technical and ethical challenges of performing PGT-M for PJS. METHODS AND RESULTS: Case 1: A 36-year-old male with PJS and his partner were referred for genetic counseling. The patient carried a pathogenic de novo variant in STK11. After a terminated pregnancy of a fetus carrying the same pathogenic variant, microsatellite polymorphic marker analysis was established, and the patient was offered PGT-M. The female partner of the patient gave birth to a healthy boy after five years of fertility treatment. Case 2: A 35-year-old female with PJS and her partner were referred for genetic counseling. She carried an inherited pathogenic STK11 variant. The couple was offered PGT-M. Genetic testing of the embryos was performed using microsatellite polymorphic markers. After two rounds of oocyte extraction a blastocyst predicted not to be affected by PJS was identified. The blastocyst was transferred; however, this did not result in a viable pregnancy. CONCLUSIONS: PGT-M can be offered to patients with PJS. The process may be long and filled with ethical dilemmas requiring patients to be motivated and persistent.

Can tandem alternative splicing and evasion of premature termination codon surveillance contribute to attenuated Peutz-Jeghers syndrome?

Alternative use of short distance tandem sites such as NAGNn AG are a common mechanism of alternative splicing; however, single nucleotide variants are rarely reported as likely to generate or to disrupt tandem splice sites. We identify a pathogenic intron 5 STK11 variant (NM_000455.4:c.[735-6A>G];[=]) segregating with the mucocutaneous features but not the hamartomatous polyps of Peutz-Jeghers syndrome in two individuals. By RNAseq analysis of peripheral blood mRNA, this variant was shown to generate a novel and preferentially used tandem proximal splice acceptor (AAGTGAAG). The variant transcript (NM_000455.4:c.734_734 + 1insTGAAG), which encodes a frameshift (p.[Tyr246Glufs*43]) constituted 36%-43% of STK11 transcripts suggesting partial escape from nonsense mediated mRNA decay and translation of a truncated protein. A review of the ClinVar database identified other similar variants. We suggest that nucleotide changes creating or disrupting tandem alternative splice sites are a pertinent disease mechanism and require contextualization for clinical reporting. Additionally, we hypothesize that some pathogenic STK11 variants cause an attenuated phenotype.

Juvenile polyposis syndrome: An overview.

Juvenile polyposis syndrome (JPS) is a rare precancerous condition that confers an increased risk of developing gastrointestinal cancers. The inheritance pattern is autosomal dominant. JPS should be clinically suspected when the other hamartomatous polyposis syndromes are excluded (i.e., Peutz- Jeghers and Cowden), in presence of numerous juvenile polyps in the colorectum or in other GI locations. Among the syndromic features, JPS can present with concomitant extra-intestinal manifestations, above all cutaneous manifestations such as telangiectasia, pigmented nevi, and skeletal stigmata. Pathogenic germline variants of either BMPR1A or SMAD4 cause the syndrome. In JPS a cumulative risk of CRC of 39-68% has been estimated. The oncological risk justifies and imposes prevention strategies that aim at the cancer risk reduction through endoscopic screening, as recommended by international scientific societies. The aim of this review is to summarize clinical and genetic features of JPS and to elucidate the steps of the clinical management from diagnosis to surveillance.

PTEN and LKB1 are differentially required in Gli1-expressing mesenchymal cells to suppress gastrointestinal polyposis.

PTEN and LKB1 are intimately associated with gastrointestinal tumorigenesis. Mutations of PTEN or LKB1 lead to Cowden syndrome and Peutz-Jeghers syndrome characterized by development of gastrointestinal polyps. However, the cells of origin of these polyps and underlying mechanism remain unclear. Here, we reveal that PTEN or LKB1 deficiency in Gli1+ gut mesenchymal cells, but not intestinal epithelium, drives polyp formation histologically resembling polyposis in human patients. Mechanistically, although PTEN and LKB1 converge to regulate mTOR/AKT signaling in various tumor contexts, we find that mTOR is essential for PTEN-deletion-induced polyp formation but is largely dispensable for polyposis induced by mesenchymal LKB1 deficiency. Altogether, our studies identify Gli1-expressing mesenchymal cells as a common cell of origin for polyposis associated with PTEN and LKB1 and reveal their engagement of different downstream pathways in gut mesenchyme to suppress gastrointestinal tumorigenesis.

68 Ga-FAPI-04 Versus 18 F-FDG PET/CT in a Case of Peutz-Jeghers Syndrome.

ABSTRACT: Peutz-Jeghers syndrome is a rare inherited hamartomatous polyposis syndrome. We describe 68 Ga-FAPI-04 and 18 F-FDG PET/CT findings in a case of Peutz-Jeghers syndrome with primary duodenal clear cell sarcoma, peritoneal metastases, and multiple intestinal polyps varying in size. The duodenal tumor and its metastases showed increased FDG and FAPI uptake. The peritoneal metastases were delineated more clearly on FAPI PET/CT compared with FDG PET/CT. More interestingly, the intestinal polyps showed increased FDG uptake and no FAPI uptake.

Multidisciplinary management for Peutz-Jeghers syndrome and prevention of vertical transmission to offspring using preimplantation genetic testing.

BACKGROUND: Peutz Jeghers syndrome (PJS) is an autosomal dominant genetic disorder caused by STK11 mutation with a predisposition to gastrointestinal polyposis and cancer. PJS patients suffer poor quality of life and are highly concerned about whether deleterious mutations transmit to their offspring. Therefore, this study aimed to propose feasible clinical management and provide effective preimplantation genetic testing for monogenic defect (PGT-M) strategies to protect offspring from inheriting the disease. METHODS: A hospital-based clinical retrospective analysis reviewing the clinical characteristics and fertility aspects was first conducted on 51 PJS patients at the First Affiliated Hospital of Zhengzhou University between January 2016 and March 2021. Among the 51 patients, the PGT-M strategy was further carried out in 4 couples, which started with a biopsy of the trophectoderm cells of embryos and whole genome amplification using multiple displacement amplification. Thereafter, single nucleotide polymorphism linkage analyses based on karyomapping were performed with copy number variations of the embryos identified simultaneously. Finally, prenatal diagnosis was used to verify the validity of the PGT-M results. RESULTS: A comprehensive management flowchart adopted by the multidisciplinary team model was formulated mainly focusing on clinical genetic and gastrointestinal aspects. Under the guidelines of this management, 32 embryos from 4 PJS pedigrees were diagnosed and 2 couples successfully conceived healthy babies free of the STK11 pathogenic mutation. CONCLUSIONS: Our comprehensive management could help affected families avoid having children with PJS through preimplantation genetic testing and provide meaningful guidance for multidisciplinary clinical practice on PJS.

Sex-Cord Tumor with Annular Tubules with Unusual Morphology in an Infant with Peutz-Jeghers Syndrome.

Background Peutz-Jeghers syndrome (PJS) is characterized by hamartomatous gastrointestinal polyposis, mucocutaneous pigmentation and cancer predisposition. The clinical features of PJS manifest in first two decades of life; however, neonatal presentation is uncommon. Case report: We present a five day old girl with PJS that presented with obstructive hamartomatous polyps in the sigmoid colon. At colostomy closure at six months, an incidental ovarian sex-cord tumor with annular tubules (SCTAT) was detected. It showed predominantly a solid pattern with limited tubule formation and was composed of lipid-rich cells. She had no hormonal symptoms. Conclusion: SCTAT can occur as young as six months of age in PJS, and may show histologic overlap with lipid-rich Sertoli cell tumors.

A novel pathogenic splice site variation in STK11 gene results in Peutz-Jeghers syndrome.

BACKGROUND: Peutz-Jeghers syndrome (PJS) is a rare autosomal dominantly inherited disease resulting in multiple gastrointestinal hamartomatous polyps, mucocutaneous pigmentation, and an increased risk of various types of cancer, and is caused by variations in the serine/threonine protein kinase STK11 (LKB1). METHODS: STK11 gene variations were identified by analyzing STK11 cDNA and genomic DNA. Minigenes carrying the wild-type and mutant sequences were subjected to in vitro splicing assay to dissect the features of these mutations. The different distribution of wild-type and mutant protein in cells were tested by Immunofluorescence assays and the functional analysis of the variation were performed using Western blot. RESULTS: A novel heterozygous splice-acceptor site variation (c.921-2 A>C) in intron 7 of the STK11 gene which is co-segregates with the PJS phenotypes in the proband and all the affected family members and three previously reported variations (c.180C>G, c.580G>A, c.787_790del) were identified in the four families. The c.921-2 A>C substitution resulted in the inactivation of a splice site and the utilization of a cryptic splice acceptor site surrounding exon 8, generating three different aberrant RNA transcripts, leading to frameshift translation and protein truncation. The results of minigenes indicated that the spliceosome can use a variety of 3' acceptor site sequences to pair with a given 5' donor site. The immunofluorescent visualization showed that the distribution of mutant STK11 was different from that of wild-type STK11, suggesting the mutation may be the causative effect on the dysfunction of the mutant protein. The rescue experiments indicated that the failure of suppressing mTOR phosphorylation by shRNA STK11 could be eliminated by supply of wild-type STK11 rather than mutant STK11. CONCLUSION: We identified a novel heterozygous mutation (c.921-2 A>C) in the STK11 in a Chinese PJS family. Haploinsufficiency of STK11 might contribute to the pathogenesis of the disease.

Histologic heterogeneity and syndromic associations of non-ampullary duodenal polyps and superficial mucosal lesions.

BACKGROUND: Duodenal polyps and superficial mucosal lesions (DP/SMLs) are poorly characterised. AIMS: To describe a series of endoscopically-diagnosed extra-ampullary DPs/SMLs. METHODS: This is a retrospective study conducted in a tertiary referral Endoscopy Unit, including patients who had DPs or SMLs that were biopsied or removed in 2010-2019. Age, gender, history of familial polyposis syndromes, DP/SML characteristics were recorded. Histopathological, immunohistochemical and molecular analyses were performed. RESULTS: 399 non-ampullary DP/SMLs from 345 patients (60.6% males; median age 67 years) were identified. Gastric foveolar metaplasia represented the most frequent histotype (193 cases, 48.4%), followed by duodenal adenomas (DAs; 77 cases, 19.3%). Most DAs (median size 6 mm) were sessile (Paris Is; 48%), intestinal-type (96.1%) with low-grade dysplasia (93.5%). Among syndromic DAs (23%), 15 lesions occurred in familial adenomatous polyposis 1, two were in MUTYH-associated polyposis and one was in Peutz-Jeghers syndrome (foveolar-type, p53-positive, low-grade dysplasia). Only one (3.3%) tubular, low-grade DA showed mismatch repair deficiency (combined loss of MLH1 and PMS2, heterogeneous MSH6 expression), and it was associated with a MLH1 gene germline mutation (Lynch syndrome). CONCLUSION: DPs/SMLs are heterogeneous lesions, most of which showing foveolar metaplasia, followed by low-grade, intestinal-type, non-syndromic DAs. MMR-d testing may identify cases associated with Lynch syndrome.