For Familial Adenomatous Polyposis Research Articles

Abstract SY07-02: Cell competition vs cell cooperation: Unlocking oncogenic potential of mutant clones in the gut

Abstract The epithelial monolayer of the intestine is one of the fastest renewing tissues of the human body. Every week, the entire epithelium is replaced by intestinal stem cells (ISCs) that reside in crypt-like structures within the monolayer. Within these crypts, a small number of ISCs continuously divide to provide all specialized cell types necessary to maintain normal intestinal homeostasis, while simultaneously competing with each other for a position within the crypt bottom. This competition, characterized by neutral loss-and-replacement events, can be drastically disturbed when one of the ISCs acquires a mutation that confers a competitive advantage. As a result, mutant ISCs will replace all normal ISCs, colonize the intestinal crypt, and facilitate the initiation of colorectal cancer (CRC). CRC development is a stepwise process characterized by the accumulation of mutations in cancer driver genes over time. Almost 80% of all CRCs present with early mutations in the tumor suppressor gene APC, leading to constitutive activation of the Wnt pathway and the formation of pre-malignant adenomas. We have previously demonstrated that, within individual crypts, Apc-mutant ISCs have a competitive advantage over normal ISCs, although the mechanism underlying this unequal competition remained unclear. Recently, we revealed that Apc-mutant ISCs in fact act as "supercompetitors" by secreting Wnt antagonists such as NOTUM, WIF1 and DKK2, that actively disadvantage neighboring wild type ISCs by forcing them do differentiate. We demonstrated that boosting wild type fitness by downstream pharmacological activation of the Wnt signaling pathway by GSK3β-inhibitor lithium rendered wild type ISCs resistant to the Wnt antagonists, reduced the number of Apc-mutant crypts, and prevented adenoma formation. Together, this work highlights that modulating cell competition between normal and mutant cells within the crypt can provide a novel approach to prevent CRC development. Our findings are particularly relevant for familial adenomatous polyposis (FAP) patients, that carry germline mutations in APC and are predisposed to the development of CRC. Based on our fundamental discoveries, we are currently performing a clinical trial to assess the chemopreventive effect of lithium on the expansion of APC-mutant clones in FAP patients [ClinicalTrials.gov: NCT05402891]. Importantly, it is becoming increasingly evident that intestinal adenomas do not form from a single Apc-mutant crypt, but require fields of multiple mutant crypts to facilitate tumor initiation. Although field cancerization by enhanced crypt fission has been observed for several oncogenic mutants in the gut (e.g. KrasG12D, PIK3CAH1047R), Apc-mutant cells are often contained within individual crypts. This indicates that multiple independent mutant clones may act cooperatively to facilitate tumorigenesis, thereby pointing towards a polyclonal origin of intestinal adenomas. Our current work investigates how Apc-mutant clones interact by modifying their local environment through reciprocal signalling with stromal and epithelial cells to escape the anatomical constraints of the crypt, thereby unlocking their oncogenic potential in the gut. Ultimately, unravelling the molecular mechanisms underlying clonal cooperation will inform potential chemoprevention strategies for CRC. Citation Format: Sanne van Neerven. Cell competition vs cell cooperation: Unlocking oncogenic potential of mutant clones in the gut [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr SY07-02.

Long-term outcomes of pouch surveillance and risk of neoplasia in familial adenomatous polyposis.

Long-term pouch surveillance outcomes for familial adenomatous polyposis (FAP) are unknown. We aimed to quantify surveillance outcomes and to determine which of selected possible predictive factors are associated with pouch dysplasia. Retrospective analysis of collected data on 249 patients was performed, analyzing potential risk factors for the development of adenomas or advanced lesions ( ≥ 10 mm/high grade dysplasia (HGD)/cancer) in the pouch body and cuff using Cox proportional hazards models. Kaplan-Meier analyses included landmark time-point analyses at 10 years after surgery to predict the future risk of advanced lesions. Of 249 patients, 76 % developed at least one pouch body adenoma, with 16 % developing an advanced pouch body lesion; 18 % developed an advanced cuff lesion. Kaplan-Meier analysis showed a 10-year lag before most advanced lesions developed; cumulative incidence of 2.8 % and 6.4 % at 10 years in the pouch body and cuff, respectively. Landmark analysis suggested the presence of adenomas prior to the 10-year point was associated with subsequent development of advanced lesions in the pouch body (hazard ratio [HR] 4.8, 95 %CI 1.6-14.1; P = 0.004) and cuff (HR 6.8, 95 %CI 2.5-18.3; P < 0.001). There were two HGD and four cancer cases in the cuff and one pouch body cancer; all cases of cancer/HGD that had prior surveillance were preceded by ≥ 10-mm adenomas. Pouch adenoma progression is slow and most advanced lesions occur after 10 years. HGD and cancer were rare events. Pouch phenotype in the first decade is associated with the future risk of developing advanced lesions and may guide personalized surveillance beyond 10 years.

Surgical strategies for hereditary colorectal cancer

Hereditary colorectal cancer (hCRC) represents amajor diagnostic and therapeutic challenge. In addition to the usual diagnostic methods, the family history, histological confirmation and mutation analysis play an important role in identifying the type of hereditary CRC. The diagnosis and classification of hCRC are carried out based on the anamnesis, clinical presentation and histology and the further treatment is determined depending on the underlying type of hCRC. For familial adenomatous polyposis (FAP) coloproctomucosectomy after the end of puberty is always recommended, whereas the treatment recommendations for other forms, such as attenuated FAP (aFAP), MUTYH-associated polyposis (MAP) and hereditary nonpolyposis colon cancer (HNPCC, Lynch syndrome), range from close surveillance and endoscopic control, through segmental resection up to colectomy. Irrespective of the type of hCRC, the treatment regimens necessitate an individualized approach and require close interdisciplinary cooperation. When colorectal resection is performed, minimally invasive procedures should principally be prioritized and some studies could demonstrate apotential benefit of robotic surgery compared to laparoscopy.

DOP70 Crohn’s Disease Like Inflammation of The Pouch is a Distinct Type of Pouchitis

Abstract Background Pouchitis occurs in up to 80% of patients with ulcerative colitis (UC) after total proctocolectomy (TPC) with ileal pouch anal anastomosis (IPAA). The pathogenesis of pouchitis is unclear, but is thought to involve a complex interaction between the microbiome and mucosal immune system. To examine the underlying pathophysiological mechanisms of pouchitis, the present study aims to simultaneously define immuno-histological and microbial parameters associated with different pouch phenotypes. Methods Endoscopic biopsies from the pre-pouch ileum (PI) and the pouch body (PB) were obtained from 51 subjects age&amp;gt;18 who underwent TPC with IPAA, n=48 for UC and n=3 for familial adenomatous polyposis (FAP). Mucosal mononuclear cells (MMC) were isolated from the intra-epithelial compartment (IEC) and lamina propria (LP) and examined for lymphoid, myeloid and innate immune subsets by multiparameter flow-cytometry (FC). Histological sections were examined by two pathologists, blinded to clinical identifiers and scored for inflammatory parameters that included neutrophilic activity, lymphoplasmacytic infiltration, eosinophilia, villous atrophy and submucosal fibrosis. Metagenomic sequencing of stool was performed and analyzed for microbial beta and alpha diversity. Results IPAA subjects were classified into the following phenotypes: normal pouch (NP) n=15 (29.4%), acute pouchitis (AP) n=9 (17.6%), chronic antibiotic dependent pouchitis (CADP) n=9 (17.6%), Crohn’s disease like pouch inflammation (CDLPI) n=15 (29.4%), and FAP NP n=3 (5.9%). Among subjects with NP, the PB had a higher frequency of naïve-CD4+ and CD8+ T cells, central memory- CD4+ T cells, and naïve B cells and a lower frequency of homeostatic IELs relative to the PI (Fig. 1A). Immune remodeling of the PB was further confirmed on histology that demonstrated increased lymphoid aggregates and decreased IELs. Subjects with CDLPI had significantly higher levels of inflammation, chronicity, and lymphoid aggregates but decreased IELs in the PI than NP or AP patients (Fig. 1B and 1C). In contrast to immune parameters, the composition of the microbiota in non-inflamed UC pouches was more similar to inflamed UC pouches than to FAP pouches. Alpha diversity and genus relative abundance differences between UC and FAP pouch stool samples were not statistically significant (Fig. 1D). Conclusion CDLPI represents a distinct entity of pouchitis that is associated with heightened levels of chronic inflammation relative to AP despite similarities in microbiota.

Results of surgical treatment for familial adenomatous polyposis

Aim: to analyze the results of surgery for familial adenomatous polyposis (FAP). Patients and methods: the case series study included 20 patients with FAP, 85 % of procedures with anastomosis and 15 % with a permanent ileostomy. Laparoscopic approach was used in 35 %. Results: the mean time of operation time was 243 minutes, the mean intraoperative blood loss was 244 ml, and the mean hospital stay was 17.2. Three (15.0 %) patients developed postoperative complications. Laparoscopic pro­cedures were advantageous in terms of intraoperative blood loss and faster recovery. The first polyps were detected in the rectal stump within 6-8 months after surgery, desmoid tumors within 24.3 months. Most patients had an acceptable quality of life with an mean number of stools per day 11.1. Conclusions: FAP is a complex problem of modern medicine requiring the teamwork of various medical specialists. Minimally invasive interventions for FAP have advantages over open procedures.

Complicaciones asociadas al reservorio ileal en colitis ulcerativa versus poliposis familiar adenomatosa: Impacto en la calidad de vida del paciente

BackgroundProctocolectomy with ileal reservoir is the surgical procedure of choice for patients with ulcerative colitis and familial adenomatous polyposis. ObjectivesTo evaluate long-term postoperative complications (1994-2019) in patients operated for familial adenomatous polyposis (FAP) and ulcerative colitis (UC) and the degree of satisfaction with the procedure. MethodsObservational study based on the analysis of a retrospective database with prospective follow-up in 115 consecutive patients: 79 with UC and 36 with FAP. A total of 88 patients were followed up, 60 with UC and 28 with PFA. Results48 males (54.4%) with a mean age of 44.8 ± 10.6 years were evaluated. Indications for surgery were intractable disease in 54 patients (47%), dysplasia/cancer in 43 (37%), severe bleeding in 4 (4%) and perforation in 3 (3%). A proctectomy and mucosectomy of the rectal stump was performed in 67 (76.1%), and a double stapling technique in 21. A protective ileostomy was performed in all patients with UC and FAP. No differences were found in early complications between the two groups. Late complications showed a higher rate of reservoritis in UC patients compared to FAP (44.9 vs. 14.3%, p = 0.001), with more refractory reservoritis in the UC group (13.3 vs. 0%, p = 0.04) with no differences in bowel obstruction, strictures, or anastomotic fistulas. Overall satisfaction and adaptation were considered good in 87% of UC patients and only 57% in the FAP group (p < 0.01). ConclusionsProctocolectomy with ileal reservoir has comparable morbidity and mortality, except for the higher rate of reservoritis in patients with a history of UC, despite this contingency there is a better quality of life and greater acceptance of surgery in UC patients than in FAP patients.

Report from 'ESCP 2021 Virtual': the 16th Scientific and Annual Conference of the European Society of Coloproctology, 22-24 September 2021.

Report from 'ESCP 2021 Virtual': the 16th Scientific and Annual Conference of the European Society of Coloproctology, 22-24 September 2021.

Wild-type APC Influences the Severity of Familial Adenomatous Polyposis.

Germline mutations in the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis (FAP). FAP patients develop multiple colonic adenomas early in life. The number of polyps can vary considerably because of different mutations1 but also for family members carrying the same mutation.2 Several genes have been considered as modifiers for the intrafamilial severity differences.3

Characterizing Pediatric Familial Adenomatous Polyposis in Patients Undergoing Colectomy in the United States

To characterize a multi-institutional cohort of pediatric patients who underwent colectomy for familial adenomatous polyposis (FAP). In this retrospective cohort study, diagnosis and procedure codes were used to identify patients who underwent colectomy for FAP within the Pediatric Health Information System (PHIS). The inclusion criteria were validated at 3 children's hospitals and applied to PHIS to generate a cohort of patients with FAP between 2 and 21years who had undergone colectomy between 2009 and 2019. Demographics, clinical and surgical characteristics, and endoscopic procedure trends as identified through PHIS are described. Descriptive and comparative statistics were used to analyze data. Within the PHIS, 428 pediatric patients with FAP who underwent colectomy were identified. Median age at colectomy was 14years (range 2-21years); 264 patients (62%) received an ileal pouch anal anastomosis and 13 (3%) underwent ileorectal anastomosis. Specific anastomotic surgical procedure codes were not reported for 151 patients (35%). Endoscopic assessment at the surgical institution occurred in 40% of the cohort before colectomy and in 22% of the cohort following colectomy. In this cohort, colectomy took place at an earlier age than suggested in published guidelines. Ileal pouch anal anastomosis is the predominant procedure for pediatric patients with FAP who underwent colectomy in US pediatric centers. Endoscopic assessment trends before and after surgery suggest that the surgical institution plays a limited role in the care of this population.

Abstract 2316: Analysis of APC-1B promoter region responsible for familial adenomatous polyposis

Abstract APC (APC regulator of WNT signaling pathway) is not only a gene responsible for familial adenomatous polyposis (FAP), a hereditary disease characterized by hundreds or thousands adenomatous polyps in the colon, but also plays a crucial role in sporadic human cancers. Although most of FAP cases are caused by germline mutations in the coding region of APC, deletions or point mutations in the promoter regions are involved in a limited number of cases. Previously, we reported an FAP case with a large deletion of approximately 10 kb encompassing APC promoter 1B and exon1B of the APC gene. Since precise regulatory mechanism(s) of the transcription of APC remains to be clarified, we searched in this study the regulatory domain(s) in the deleted region. First, we performed cap analysis of gene expression (CAGE) analysis, and compared the amount of APC-1A and APC-1B transcripts in the peripheral blood cells of the patient with that of healthy volunteers. As a result, we found that the deletion decreased the amount of APC-1B to 39% - 45% in the patient compared to the healthy controls, and that it did not change the amount of APC-1A in the patient. In addition, an allele-specific expression analysis by deep cDNA sequencing revealed that the amount of APC transcripts from the mutated APC allele is reduced to 11.2% by the deletion in the patient, suggesting that the deletion resulted in the marked decrease of the transcription of the affected allele and that the remaining expression of deleted allele may be driven by other regulatory region(s) such as promoter 1A. Consistently, CAGE analysis demonstrated that APC-1B transcripts are more abundantly expressed than APC-1A transcripts in all tissues tested except for the brain, suggesting that promoter 1B plays a crucial role in the expression of APC transcription. Analysis of promoter 1B by reporter assay identified a critical region for the transcriptional activation between -117 bp and -49 bp of promoter 1B. These data will contribute to the better understanding of regulatory mechanisms of APC transcription and the evaluation of genetic variants located in promoter 1B. Citation Format: Saya Nakagawa, Kiyoshi Yamaguchi, Kimiko Saito, Kiyoko Takane, Tsuneo Ikenoue, Yoichi Furukawa. Analysis of APC-1B promoter region responsible for familial adenomatous polyposis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2316.

Immune Microenvironment: New Insight for Familial Adenomatous Polyposis

Currently, the main treatment for familial adenomatous polyposis (FAP) is surgery, however, surgery is far from ideal as there are many complications such as uncontrollable bowel movements, pouch inflammation, anastomotic stricture, and secondary fibroids. Therefore, it is necessary to further expand the understanding of FAP and develop new treatments for FAP. The immune microenvironment including immune cells and cytokines, plays an important role in FAP and the progression of FAP to adenocarcinoma, thus it may be a promising treatment for FAP. In the current review, we summarized the recent progress in the immune microenvironment of FAP.

Approach to screening for Familial Adenomatous Polyposis (FAP) in a cohort of 226 patients with Desmoid-type Fibromatosis (DF): experience of a specialist center in the UK.

Desmoid-type fibromatosis (DF) are locally infiltrative, non-metastasizing tumours associated with significant morbidity and mortality if located intra-abdominally, retroperitoneally or in head and neck localisation. They are mostly sporadic, due to somatic CTNNB1 mutations. Alternatively, they can be associated with germline pathogenic variants in APC causing Familial Adenomatous Polyposis (FAP). Germline APC variants and somatic CTNNB1 mutations are mutually exclusive. We conducted a retrospective descriptive analysis of patients with DF seen at the Royal Marsden NHS Foundation Trust Sarcoma Unit in London. We aimed to describe the methods of screening for FAP in patients with DF from a specialist unit. Patients diagnosed between 1992 and 2020 were selected from the prospectively maintained Sarcoma Unit database. 226 patients were identified and 67% (n = 152) were female. Median age at diagnosis was 37.5 (range 2-81) years. Tumour localisation was limbs/pelvis in 30.9% (N = 70), intra-abdominal 16.8% (N = 38), abdominal wall 23.5% (N = 53), thorax 18.6% (N = 42), head and neck 3.1% (N = 7) and vertebral/paravertebral 7.1% (N = 16). Colonoscopy was requested in 65 patients (28.8% of all cases) and was completed in forty-six (20.4%). Molecular testing of CTNNB1 testing was requested in 35 cases (15.5%). APC germline test was requested in 12 cases. Four patients in our cohort had an FAP-associated DF. CTNNB1 ± APC testing and colonoscopy are useful tools for the screening of patients with DF. CTNNB1 molecular testing should be performed in all cases of newly diagnosed DF. Negative CTNNB1 results, alongside clinical assessment, should prompt APC testing and/or colonoscopy.

Synthetic lethality between MyD88 loss and mutations in Wnt/β-catenin pathway in intestinal tumor epithelial cells.

Although the Wnt/β-catenin pathway plays a central role in the carcinogenesis and maintenance of colorectal cancer (CRC), attempts to target the pathway itself have not been very successful. MyD88, an adaptor protein of the TLR/IL-1β signaling, has been implicated in the integrity of the intestines as well as in their tumorigenesis. In this study, we aimed to clarify the mechanisms by which epithelial MyD88 contributes to intestinal tumor formation and to address whether MyD88 can be a therapeutic target of CRC. Conditional knockout of MyD88 in intestinal epithelial cells (IECs) reduced tumor formation in Apc+/Δ716 mice, accompanied by decreased proliferation and enhanced apoptosis of tumor epithelial cells. Mechanistically, the MyD88 loss caused inactivation of the JNK-mTORC1, NF-κB, and Wnt/β-catenin pathways in tumor cells. Induction of MyD88 knockout in the intestinal tumor-derived organoids, but not in the normal IEC-derived organoids, induced apoptosis and reduced their growth. Treatment with the MyD88 inhibitor ST2825 also suppressed the growth of the intestinal tumor-derived organoids. Knockdown of MYD88 in human CRC cell lines with mutations in APC or CTNNB1 induced apoptosis and reduced their proliferation as well. These results indicate that MyD88 loss is synthetic lethal with mutational activation of the Wnt/β-catenin signaling in intestinal tumor epithelial cells. Inhibition of MyD88 signaling can thus be a novel therapeutic strategy for familial adenomatous polyposis (FAP) as well as for colorectal cancer harboring mutations in the Wnt/β-catenin signaling.

Stem cell models for genetically predisposed colon cancer.

Negative growth regulatory tumor suppressor genes and positive growth regulatory oncogenes serve important roles in initiation/progression of colon cancer. Germline mutation in the adenomatous polyposis coli (APC) tumor suppressor gene represents a primary genetic defect for familial adenomatous polyposis (FAP) syndrome, a predisposing factor for clinical colon cancer. Somatic mutations in the APC gene are common in sporadic colon cancer. Preclinical and clinical efficacy is documented for targeted therapy with non-steroidal anti-inflammatory drugs, selective cyclo-oxygenase-2 inhibitors for prostaglandin biosynthesis and selective inhibitor of ornithine decarboxylase for polyamine biosynthesis. However, these therapeutic options lead to systemic toxicity, acquired tumor resistance and emergence of therapy resistant cancer stem cells. By contrast, non-toxic natural products are unlikely to exhibit drug resistance and may represent testable alternatives for therapy resistant colon cancer. Tumorigenic Apc [-/-] colonic epithelial cell lines derived from preclinical FAP models provide novel cellular models for drug resistant cancer stem cells. Apc [-/-] Sulindac resistant (SUL-R) cells exhibit upregulated expression levels of cancer stem cell markers. Natural products, such as naturally occurring vitamin A derivative all-trans retinoic acid (ATRA) and the anti-cancer agent from Turmeric root curcumin (CUR), represent testable alternatives. Relative to the non-tumorigenic Apc [+/+] C57 COL colonic epithelial cells, the tumorigenic Apc [-/-] 1638N COL and Apc [-/-] 850 MIN COL cells exhibit aneuploid cell hyper-proliferation and upregulated expression of Apc target genes β-catenin, cyclin D1, c-myc and COX-2. The SUL-R phenotypes exhibit enhanced tumor spheroid formation and upregulated expression levels of stem cell markers CD44, CD133 and c-Myc. Treatment of the SUL-R stem cells with ATRA and CUR inhibits tumor spheroid formation and reduces the expression of stem cell markers. Stem cell models developed for FAP syndrome provide a novel experimental approach to identify mechanistic leads for efficacious natural products as testable alternatives for therapy-resistant, genetically predisposed colon cancer.

SUN-482 A Very Rare Case of Thyroid Cancer

Background: Cribriform-Morular variant of Papillary Thyroid Cancer (PTC-CMV) is an exceedingly rare subtype of thyroid cancer that predominantly affects younger females. As the name implies, it is a papillary thyroid carcinoma with predominantly cribriform and morular pattern of carcinoma cells on cytopathology. While completion thyroidectomy is usually recommended for larger and higher-risk Papillary Thyroid Cancer (PTC), surveillance may be acceptable with PTC-CMV, which tends to be a less aggressive malignancy. Clinical Case: A 46-year-old Guyanese woman presented with a three week history of an enlarging right-sided neck mass associated with a globus sensation while swallowing food. She denied any history of radiation exposure. Her exam findings were positive for a tender, right-sided neck mass. CT neck without contrast revealed a 4.1 x 4.0 x 5.9cm heterogeneous mass within the right thyroid lobe causing mild tracheal deviation to the left. Ultrasound of thyroid gland showed a solid heterogeneous hypoechoic 4.22 x 2.39 x 2.46cm right lobe nodule with no microcalcifications, border irregularity or taller-than-wider morphology. Fine Needle Aspiration of the nodule came back as Atypia of Undetermined Significance. The patient then underwent a core needle biopsy. The resultant pathology was negative for thyroid carcinoma or medullary thyroid carcinoma but was suggestive of a bronchial cleft cyst versus bronchogenic cyst with atypical glandular proliferation. She subsequently underwent a right hemithyroidectomy which revealed a final pathological diagnosis of a 3.5cm PTC-CMV. Such pathology warranted the patient to undergo a colonoscopy which was negative for Familial Adenomatous Polyposis (FAP). Given her negative GI workup and non-contributory family history for colonic polyposis or carcinoma the decision was made to continue surveillance rather than performing completion thyroidectomy as the disease was presumed to be sporadic. Discussion: PTC-CMV accounts for 0.2% of all PTC. It is associated with FAP in more than 50% of cases but can also occur sporadically. This subtype of PTC generally follows a less aggressive course. Review of current literature revealed several case series of CMV-PTC patients. In the largest one, 32 cases were observed over a 19 year period and only two out of twelve patients with FAP-associated PTC-CMV initially treated with hemithyroidectomy developed recurrence to the contralateral lobe. Interestingly, none of the remaining patients with the sporadic type developed recurrence suggesting that completion thyroidectomy may not be mandatory in this group. It is, therefore, critical to identify these patients and screen them with a colonoscopy to avoid the potentially unnecessary resection of the contralateral lobe and the consequent need for thyroid hormone replacement.

Cribriform-Morular Variant of Papillary Thyroid Carcinoma: a Clinical Surprise in a Routine Case

Cribriform morular variant of papillary thyroid carcinoma (CMV-PTC) is a rare variant. It is commonly associated with familial adenomatous polyposis. It is mostly seen in females below 30 years of age. We describe a male patient in his fourth decade of life, who presented with a solitary thyroid nodule and was evaluated and treated. The histopathology of the thyroid nodule was reported as CMV-PTC. In light of this finding, the patient was further investigated and treated for familial adenomatous polyposis (FAP), for which he was asymptomatic. Any patient diagnosed with CMV-PTC must also undergo colonoscopy to rule out FAP and receive appropriate treatment. Clinicians must be aware that this variant can be seen in men too.

Retromastoid osteoma—a rare case report

Osteomas are slow growing bone tumours and are often asymptomatic. Rarely, they can be present in the temporal bone—only few cases had been reported, with an incidence of 0.1–1%. We describe a case of an osteoma of the temporal bone (retromastoid) found in a 40 year old female, who presented with a slow growing swelling behind the right ear for 9 years. Diagnosis was made on non-contrast computed topography (CT) of the skull. Treatment is indicated in symptomatic cases or cosmetic reasons. Screening colonoscopy and genetic testing for familial adenomatous polyposis (FAP) and Gardner’s syndrome are advised.

A unique case of two somatic APC mutations in an early onset cribriform-morular variant of papillary thyroid carcinoma and overview of the literature

We report a case of a 22-year-old female patient who was diagnosed with a cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC). While at early ages this thyroid cancer variant is highly suggestive for familial adenomatous polyposis (FAP), there was no family history of FAP. In the tumor biallelic, inactivating APC variants were identified. The patient tested negative for germline variants based on analysis of genomic DNA from peripheral blood leukocytes. Somatic mosaicism was excluded by subsequent deep sequencing of leukocyte and normal thyroid DNA using next generation sequencing (NGS). This report presents a rare sporadic case of CMV-PTC, and to the best of our knowledge the first featuring two somatic APC mutations underlying the disease, with an overview of CMV-PTC cases with detected APC and CTNNB1 pathogenic variants from the literature.

PLK1 has tumor-suppressive potential in APC-truncated colon cancer cells

The spindle assembly checkpoint (SAC) acts as a molecular safeguard in ensuring faithful chromosome transmission during mitosis, which is regulated by a complex interplay between phosphatases and kinases including PLK1. Adenomatous polyposis coli (APC) germline mutations cause aneuploidy and are responsible for familial adenomatous polyposis (FAP). Here we study the role of PLK1 in colon cancer cells with chromosomal instability promoted by APC truncation (APC-ΔC). The expression of APC-ΔC in colon cells reduces the accumulation of mitotic cells upon PLK1 inhibition, accelerates mitotic exit and increases the survival of cells with enhanced chromosomal abnormalities. The inhibition of PLK1 in mitotic, APC-∆C-expressing cells reduces the kinetochore levels of Aurora B and hampers the recruitment of SAC component suggesting a compromised mitotic checkpoint. Furthermore, Plk1 inhibition (RNAi, pharmacological compounds) promotes the development of adenomatous polyps in two independent ApcMin/+ mouse models. High PLK1 expression increases the survival of colon cancer patients expressing a truncated APC significantly.

Ileal Pouch of Ulcerative Colitis Patients Exhibit Impaired Autophagy

BACKGROUND: Total rectocolectomy with ileal pouch-anal anastomosis (IPAA) is the surgery of choice for patients with ulcerative colitis (UC) that are refractory to clinical treatment and for familial adenomatous polyposis (FAP) with many rectal polyps. The main complication after this procedure is the pouch inflammation (pouchitis) that can affect up to 45 percent of patients who are submitted to IPAA for UC, and only five percent of the FAP patients who undergo the same procedure. Previous studies have shown increased pro-inflammatory cytokines in the ileal pouch (IP) mucosa of UC patients, even in the absence of clinical, endoscopic and histological inflammation. Autophagy is an evolutionarily conserved catabolic pathway that consists of selective degradation of cellular components and a homeostatic mechanism that protects cells exposed to stress situations (toxins, starvation), and defects in this pathway have been reported in inflammatory bowel diseases. However, there are no studies on the IP. Therefore, we studied markers for autophagy in the IP mucosa of UC and FAP patients comparing them to controls with a normal distal ileum. METHODS: Sixteen patients with IP in "J" shape, asymptomatic and with endoscopically normal mucosa were evaluated. The control group consisted of eight patients with normal colonoscopy. Gene expression was analyzed by qPCR and protein levels by immunoblotting and immunofluorescence. This study was approved by the Ethics Committee of the University of Campinas and was performed in accordance with the Declaration of Helsinki. All results were reported as means ± SEM. Data were analyzed by non-parametric Test, comparing all groups. The level of significance was set at P<0.05. RESULTS: There was a significant decrease in the transcriptional levels of ATG5, MAP1LC3A and BAX in the FAP group (P<0.05). There was also a decrease in the protein level of Beclin-1 in the UC and FAP compared to the control group (P<0.05). Although the LC3II levels by immunoblot were higher in the UC group, total LC3 and LC3/p62 co-localization were lower in the immunofluorescence analysis in the UC and FAP compared to the control group (P<0.05). Corroborating to these results, there was an increase of p62 by immunoblot in the UC group, compared to controls (P<0.05). CONCLUSION(S): These results indicate impaired macroautophagy mechanism in the IP. In FAP, decreased autophagy may be related to impaired apoptosis, otherwise in UC, may be mainly due to increased Toll-Like Receptors (TLR) activation. These findings may explain the inflammation predisposition, mainly in the IP mucosa of UC patients. Acknowledgments: We thank FAPESP (São Paulo Research Foundation) for financial support. Negreiros LMV (co-author) received scholarship from FAPESP. We are grateful to Prof. Tristan Torriani for English grammar revision. We thank Francesca Ramos and José Diego Botezelli for technical assistance and the staff of the Life Sciences Core Facility (LaCTAD) from State University of Campinas (UNICAMP), for the Cell Biology analysis.