Germline mutations of the PTEN gene in Cowden disease, an inherited breast and thyroid cancer syndrome

Cowden Syndrome Diagnosed by Bilateral Breast Cancer with Lhermitte-Duclos Disease: A Case Report

Cowden syndrome is extremely rare and is characterized by multiple hamartomas in various tissues, including the skin, mucous membranes, gastrointestinal tract, breast, thyroid, and brain, and has an increased risk of breast, thyroid, and uterine cancers. Here, we report a case of Cowden syndrome diagnosed following presentation with bilateral breast cancer and provide a discussion of the relevant literature. A 47-year-old woman with a tumor in her right breast was referred to our hospital. She was diagnosed with bilateral breast cancer upon imaging and underwent a bilateral mastectomy and sentinel lymph node biopsy. Previously, she had undergone total thyroidectomy to treat a thyroid tumor. Approximately 3 years later, she was diagnosed with Lhermitte-Duclos disease affecting her left cerebellar hemisphere. As her sister and mother had also been diagnosed with breast cancer, we suspected that she might have an inherited disease. Since 80% of individuals with Cowden syndrome have a mutation in the phosphatase and tension homolog (PTEN) gene, we did not perform any genetic testing. Instead, we used the syndrome’s pathognomonic criteria and major criteria (breast cancer, thyroid tumor, and Lhermitte-Duclos disease) to diagnose our patient with Cowden syndrome. While treatment of Cowden syndrome is currently limited to strategies that can manage the symptoms, patients are at an increased risk of certain cancers and require regular screening to allow for early detection of disease.

Hints from a Female Patient with Breast Cancer Who Later Presented with Cowden Syndrome

A 51-year-old woman presented with metachronous tumor development in bilateral breasts, thyroid, and endometrium. Additional signs and symptoms fulfilled the National Comprehensive Cancer Network criteria for Cowden syndrome. Immunohistochemistry showed loss of PTEN expression in all tumors. Single nucleotide variants, 647 germline variants (including one each in PTEN and MSH3), and 21 somatic mutations within exons were detected in all tumors after whole-exome sequencing. There were 0, 11, and 46 specific somatic mutations in bilateral breasts, thyroid, and endometrial cancers, respectively. Although PTEN mutation is key to the development of Cowden syndrome, DNA repair dysfunction might be the initial driver of mutations. Fewer mutations were required to induce initial bilateral breast carcinomas, with subsequent thyroid and endometrial carcinomas requiring more mutations for induction. When genetic screening is unavailable, breast cancer patients with clinical manifestations of Cowden syndrome must be carefully assessed for secondary malignancies, such as thyroid and endometrial carcinomas.

The Role of PTEN in Neurodevelopment

PTEN is a lipid and protein phosphatase that regulates cell growth and survival. Mutations to PTEN are highly penetrant for autism spectrum disorder (ASD). Here, we briefly review the evidence linking PTEN mutations to ASD and the mouse models that have been used to study the role of PTEN in neurodevelopment. We then focus on the cellular phenotypes associated with PTEN loss in neurons, highlighting the role PTEN plays in neuronal proliferation, migration, survival, morphology, and plasticity.

PTEN in Hereditary and Sporadic Cancer

Germline pathogenic phosphatase and tensin homolog (PTEN) mutations cause PTEN hamartoma tumor syndrome (PHTS), characterized by various benign and malignant tumors of the thyroid, breast, endometrium, and other organs. Patients with PHTS may present with other clinical features such as macrocephaly, intestinal polyposis, cognitive changes, and pathognomonic skin changes. Clinically, deregulation of PTEN function is implicated in other human diseases in addition to many types of human cancer. PTEN is an important phosphatase that counteracts one of the most critical cancer pathways: the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathways. Although PTEN can dephosphorylate lipids and proteins, it also has functions independent of phosphatase activity in normal and pathological states. It is positively and negatively regulated at the transcriptional level as well as posttranslationally by phosphorylation, ubiquitylation, oxidation, and acetylation. Although most of its tumor-suppressor activity is likely to be caused by lipid dephosphorylation at the plasma membrane, PTEN also resides in the cytoplasm and nucleus, and its subcellular distribution is under strict control. In this review, we highlight our current knowledge of PTEN function and recent discoveries in understanding PTEN function regulation and how this can be exploited therapeutically for cancer treatment.

An update on the CNS manifestations of brain tumor polyposis syndromes

Cancer predisposition syndromes are associated with an increased risk of developing primary malignancies. Here we discuss those which are associated with an increased risk of tumors of the central nervous system (CNS) and gastrointestinal (GI) tract. These can be grouped into those in which the CNS tumors predominate versus those in which the GI cancers predominate. The former include constitutional mismatch repair deficiency (CMMRD) syndrome, Li-Fraumeni syndrome (LFS), and Cowden syndrome (CS) while the latter include familial adenomatosis polyposis 1 (FAP1), Lynch syndrome and polymerase proofreading-associated polyposis syndrome (PPAP). Tumor specificity does exist as medulloblastoma occur in FAP, LFS and CMMRD while glioma are most commonly seen in all replication repair-deficient genes and LFS. Choroid plexus carcinoma is strictly observed in LFS while Cowden syndrome patients develop Lhermitte Duclos disease or meningioma. In each syndrome, specific types of low-grade and high-grade gastrointestinal cancers can occur, but these will be discussed elsewhere. Underlying cancer predisposition syndromes are important to consider when faced with brain tumors, particularly in the pediatric and young adult age groups, as identification of an underlying germ line mutation may change the upfront management of the patient and has implications for future cancer surveillance for both the patient and potentially affected family members. Considerations of family history, presence of skin lesions and consanguinity provide valuable information in identifying patients at potential increased risk.

The frequency of PTEN germline mutations in Chinese breast cancer patients: The PTEN gene may not be closely associated with breast cancer in the Chinese population

BACKGROUND

PTEN is a tumour suppressor gene that has been proven to be related to breast cancer incidence and tumour progression. The aim of this study was to investigate the frequency of PTEN mutations in breast carcinomas in China and the relationships of PTEN mutations with clinicopathological parameters and clinical outcomes.

MATERIAL AND METHODS

Trimmomatic, Burrows-Wheeler Aligner (BWA), ANNOVAR, SAMtools, and Sanger sequencing were used to analyse PTEN mutations and identify variants in Chinese breast cancer. The frequency of PTEN mutations and the relationships of PTEN mutations with clinicopathological parameters and clinical outcomes were evaluated in breast carcinomas in China.

RESULTS

The rate of PTEN germline mutation was 0.23% (n = 9) among 3955 unselected primary breast cancer patients. Of these 9 patients, 2 carried pathogenic mutations, and both were identified as having infiltrative carcinoma. One patient had a family history. The other 7 patients carried only PTEN germline variants that were not identified as pathogenic mutations.

CONCLUSIONS

We studied the frequency of PTEN germline mutations in a sequential cohort of Chinese breast carcinoma patients. Based on these data, we hypothesize that the germline mutation of the PTEN gene is not closely related to the occurrence of breast cancer in the Chinese population. In the clinic, the PTEN germline mutation cannot be used as the basis for the detection of breast cancer.

Inherited kidney cancer syndromes

PURPOSE OF REVIEW

To describe current paradigms for genetic testing, screening, and treatment of patients with inherited kidney cancer syndromes.

RECENT FINDINGS

We describe various new aspects of hereditary kidney cancer. Recent data now support that hereditary kidney cancer may account for 5-8% of kidney cancers diagnosed. Methods of testing have evolved including the introduction of multigene next-generation sequencing panels. We continue to learn more about the natural history and management of classic hereditary cancer syndromes. New emerging conditions with lower kidney cancer penetrance have been recognized adding the growing list of syndromes associated with kidney cancer development. The surgical management strategies of enucleation remain however systemic therapy options are being explored both for localized and advanced settings.

SUMMARY

Genetic predisposition to kidney cancer is likely more common than once thought. Knowledge of clinical manifestation and genetic testing strategies are needed to properly identify and treat patient and their families.

PTEN modulates gene transcription by redistributing genome-wide RNA polymerase II occupancy

Control of gene expression is one of the most complex yet continuous physiological processes impacting cellular homeostasis. RNA polymerase II (Pol II) transcription is tightly regulated at promoter-proximal regions by intricate dynamic processes including Pol II pausing, release into elongation and premature termination. Pol II pausing is a phenomenon where Pol II complex pauses within 30–60 nucleotides after initiating the transcription. Negative elongation factor (NELF) and DRB sensitivity inducing factor (DSIF) contribute in the establishment of Pol II pausing, and positive transcription elongation factor b releases (P-TEFb) paused complex after phosphorylating DSIF that leads to dissociation of NELF. Pol II pausing is observed in most expressed genes across the metazoan. The precise role of Pol II pausing is not well understood; however, it’s required for integration of signals for gene regulation. In the present study, we investigated the role of phosphatase and tensin homolog (PTEN) in genome-wide transcriptional regulation using PTEN overexpression and PTEN knock-down models. Here we identify that PTEN alters the expression of hundreds of genes, and its restoration establishes genome-wide Pol II promoter-proximal pausing in PTEN null cells. Furthermore, PTEN re-distributes Pol II occupancy across the genome and possibly impacts Pol II pause duration, release and elongation rate in order to enable precise gene regulation at the genome-wide scale. Our observations demonstrate an imperative role of PTEN in global transcriptional regulation that will provide a new direction to understand PTEN-associated pathologies and its management.

Structural Mechanisms of PTEN Regulation

The tumor suppressor phosphatase and tensin homolog on chromosome 10 (PTEN) is a tightly regulated enzyme responsible for dephosphorylating the progrowth lipid messenger molecule phosphatidylinositol 3,4,5-trisphosphate (PIP₃) on the plasma membrane. The carboxy-terminal tail (CTT) of PTEN is key for regulation of the enzyme. When phosphorylated, the unstructured CTT interacts with the phosphatase-C2 superdomain to inactivate the enzyme by preventing membrane association. PTEN mutations associated with cancer also inactivate the enzyme. Alternate translation-initiation sites generate extended isoforms of PTEN, such as PTEN-L that has multiple roles in cells. The extended amino-terminal region bears a signal sequence and a polyarginine sequence to facilitate exit from and entry into cells, respectively, and a membrane-binding helix that activates the enzyme. This amino-terminal region also facilitates mitochondrial and nucleolar localization. This review explores PTEN structure and its impact on localization and regulation.

Germline mutations of multiple breast cancer-related genes are differentially associated with triple-negative breast cancers and prognostic factors

Genetic testing for BRCA1/2 mutations has become the standard clinical practice. Recent findings suggest the clinical significance of multigene panel testing of BRCA1/2 and other cancer-related genes. However, the clinical features of patients with breast cancer with germline mutations identified using multigene panels remain unclear. In this study, DNA samples from 583 Chinese women with breast cancer were subjected to target sequencing for 54 cancer-related genes using a pre-capture pooling method followed by next-generation sequencing. We identified 79 pathogenic germline mutations in 21 cancer-related genes. Forty-five patients (7.7%) harbored BRCA1/2 mutations, and 38 patients (6.5%) carried pathogenic mutations in the remaining 19 genes. PALB2 was the most commonly (1.2%) mutated gene other than BRCA1/2. Most of the identified pathogenic mutations were novel, suggesting mutation screening by using multigene panel testing is important particularly for non-European populations. Mutations in BRCA1/2 and the other cancer-related genes were differentially associated with clinical features. BRCA1 mutation carriers were strongly associated with triple-negative breast cancer (TNBC), whereas BRCA2 mutation carriers were not. Tumors in BRCA1-mutation carriers had a high histological grade. Patients with BRCA2-mutated breast cancers were likely to develop E-cadherin-negative tumors with bone metastases. Furthermore, mutations in PALB2 were strongly associated with TNBC. We demonstrated the usefulness of multigene panel testing and observed that a substantial proportion of patients with breast cancer had hereditary risk factors. Identifying differential associations between mutation status and clinical features will advance our understanding regarding the pathologies of this heterogeneous disease.

PTEN Mouse Models of Cancer Initiation and Progression

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is one of the most frequently mutated, deleted, and functionally inactivated tumor suppressor genes in human cancer. PTEN is found mutated both somatically and in the germline of patients with PTEN hamartoma tumor syndrome (PHTS). PTEN encodes a dual lipid and protein phosphatase that dephosphorylates the lipid phosphatidylinositol-3,4,5-trisphosphate (PIP₃), in turn negatively regulating the oncogenic PI3K-AKT pathway, a key proto-oncogenic player in cancer development and progression. Because of importance of PTEN in tumorigenesis, a large number of sophisticated genetically engineered mouse models (GEMMs) has been designed to elucidate the underlying mechanisms by which the "PTEN pathway" promotes tumorigenesis, while simultaneously providing a well-tailored system for the identification of novel therapies and offering platforms for new drug discoveries. This review summarizes the major cancer mouse models through which the PTEN pathway has been genetically deconstructed, and outlines the rapid development of GEMMs toward more detailed functional and tissue-specific analysis.

Phenotype-to-genotype approach reveals head-circumference-associated genes in an autism spectrum disorder cohort

The genotype-first approach has been successfully applied and has elucidated several subtypes of autism spectrum disorder (ASD). However, it requires very large cohorts because of the extensive genetic heterogeneity. We investigate the alternate possibility of whether phenotype-specific genes can be identified from a small group of patients with specific phenotype(s). To identify novel genes associated with ASD and abnormal head circumference using a phenotype-to-genotype approach, we performed whole-exome sequencing on 67 families with ASD and abnormal head circumference. Clinically relevant pathogenic or likely pathogenic variants account for 23.9% of patients with microcephaly or macrocephaly, and 81.25% of those variants or genes are head-size associated. Significantly, recurrent pathogenic mutations were identified in two macrocephaly genes (PTEN, CHD8) in this small cohort. De novo mutations in several candidate genes (UBN2, BIRC6, SYNE1, and KCNMA1) were detected, as well as one new candidate gene (TNPO3) implicated in ASD and related neurodevelopmental disorders. We identify genotype-phenotype correlations for head-size-associated ASD genes and novel candidate genes for further investigation. Our results also suggest a phenotype-to-genotype strategy would accelerate the elucidation of genotype-phenotype relationships for ASD by using phenotype-restricted cohorts.

NS-Pten adult knockout mice display both quantitative and qualitative changes in urine-induced ultrasonic vocalizations

The NS-Pten knockout (KO) mouse exhibits hyperactivity of the mammalian target of rapamycin (mTOR) and is a model of autism spectrum disorder (ASD). ASD presents with marked deficits in communication which can be elucidated by investigating their counterpart in mice, ultrasonic vocalizations (USVs). While USVs have been found to be altered in NS-Pten KO pups, no study has assessed whether this communication deficit persists into adulthood. In the present study, we investigate female urine-induced USVs, scent marking behavior, and open field activity in NS-Pten KO and wildtype (WT) adult male mice. Results showed that there was no difference in the quantity of vocalizations produced between groups, however, there were extensive alterations in the spectral properties of USVs. KO mice emitted vocalizations of a lower peak frequency, shorter duration, and higher peak amplitude compared to WT mice. KO animals also emitted a significantly different distribution of call-types relative to controls, displaying increased complex and short calls, but fewer upward, chevron, frequency steps, and composite calls. No significant differences between groups were observed for scent marking behavior and there was no difference between groups in the amount of time spent near the female urine. Overall, this study demonstrated that mTOR hyperactivity contributes to communication deficits in adult mice.

Analysis of Site-Specific Phosphorylation of PTEN by Using Enzyme-Catalyzed Expressed Protein Ligation

The activity and localization of PTEN, a tumor suppressor lipid phosphatase that converts the phospholipid PIP3 to PIP2, is governed in part by phosphorylation on a cluster of four Ser and Thr residues near the C terminus. Prior enzymatic characterization of the four monophosphorylated (1p) PTENs by using classical expressed protein ligation (EPL) was complicated by the inclusion of a non-native Cys at the ligation junction (aa379), which may alter the properties of the semisynthetic protein. Here, we apply subtiligase-mediated EPL to create wt 1p-PTENs. These PTENs are more autoinhibited than previously appreciated, consistent with the role of Tyr379 in driving autoinhibition. Alkaline phosphatase sensitivity analysis revealed that these autoinhibited 1p conformations are kinetically labile. In contrast to the Cys mutant 1p-PTENs, which are poorly recognized by an anti-phospho-PTEN antibody, three of the four wt 1p-PTENs are recognized by a commonly used anti-phospho-PTEN antibody.

Copy Number Variation and Clinical Outcomes in Patients With Germline PTEN Mutations

IMPORTANCE

PTEN is among the most common autism spectrum disorder (ASD)-predisposition genes. Germline PTEN mutation carriers can develop malignant neoplasms and/or neurodevelopmental disorders such as ASD and developmental delay. Why a single gene contributes to disparate clinical outcomes, even in patients with identical PTEN mutations, remains unclear.

OBJECTIVE

To investigate the association of copy number variations (CNVs), altered numbers of copies of DNA sequences within the genome, with specific phenotypes in patients with germline PTEN mutations.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study examined genome-wide microarrays performed on blood-derived DNA to detect germline CNVs from September 1, 2005, through January 3, 2018. Multicenter accrual occurred from community and academic medical centers throughout North America, South America, Europe, Australia, and Asia. Participants included patients with PTEN hamartoma tumor syndrome (PHTS) (n = 481), molecularly defined as carrying germline pathogenic PTEN mutations. Data were analyzed from November 14, 2018, to August 1, 2019.

EXPOSURES

Detection of CNVs from patient-derived germline DNA.

MAIN OUTCOMES AND MEASURES

Prevalence of pathogenic and/or likely pathogenic CNVs in patients with PHTS and association with ASD/developmental delay and/or cancer, ascertained through medical records and pathology reports.

RESULTS

The study included 481 patients with PHTS (mean [SD] age, 33.2 [21.6] years; 268 female [55.7%]). The analytic series consisted of 309 patients with PHTS and genetically determined European ancestry. Patients were divided into 3 phenotypic groups, excluding family members within each group. These include 110 patients with ASD/developmental delay, 194 without ASD/developmental delay, and 121 with cancer (of whom 116 were in the no ASD/developmental delay group). Genome-wide evaluation of autosomal CNVs indicated an increased CNV burden, particularly duplications in genic regions, in patients with ASD/developmental delay compared with those without ASD/developmental delay (odds ratio [OR], 1.9; 95% CI, 1.1-3.4; P = .03) and those with cancer (OR, 2.5; 95% CI, 1.3-4.6; P = .003). Eleven of the 110 patients (10.0%) with ASD/developmental delay carried pathogenic and/or likely pathogenic CNVs associated with neurodevelopmental disorders, compared with 5 of 194 (2.6%) without ASD/developmental delay (OR, 4.2; 95% CI, 1.4-13.7; P = .008) and 2 of 121 (1.7%) with cancer (OR, 6.6; 95% CI, 1.6-44.5; P = .007). Evidence of an association between pathogenic and/or likely pathogenic CNVs and PHTS with ASD/developmental delay was further supported in a validation series of 69 patients with PHTS of genetically determined non-European ancestry.

CONCLUSIONS AND RELEVANCE

These findings suggest that copy number variations are associated with the ASD/developmental delay clinical phenotype in PHTS, providing proof of principle for similarly heterogeneous disorders lacking outcome-specific associations.

Ductal carcinoma in situ of the breast arising in encapsulated mammary hamartoma ; A case report

Mammary hamartoma is benign lesion and relatively rare. 17 cases of breast cancer associated with a hamartoma had been previously documented in the literature. We describe herein a case of noninvasive ductal carcinoma of the breast arising in hamartoma in a woman of 60's. The discordance of images of the mass between mammogram and ultrasonogram can lead us to detect the carcinoma within the hamartoma in our case. J. Med. Invest. 67 : 368-371, August, 2020.

Spectrum of gastrointestinal tract pathology in a multicenter cohort of 43 Cowden syndrome patients

Most patients with Cowden syndrome have lesions in the gastrointestinal tract, characterized by multiple polyps of various histologic types in the large bowel, polyps in the upper gastrointestinal tract, and esophageal glycogenic acanthosis. However, pathologists are often unaware of the distinctive polyposis phenotype of Cowden syndrome. In this multicenter study, we report the spectrum of gastrointestinal manifestations in a series of 43 Cowden syndrome patients who had at least one endoscopy. The median age at the first endoscopy was 46 years and 58% were women. In 24 of 29 (83%) tested patients, a pathogenic germline mutation in PTEN was identified. The histology from 199 endoscopy procedures (67 upper gastrointestinal endoscopy and 132 colonoscopies) was reviewed. Hamartomatous polyps of the large bowel were the most common lesions, present in 85% of patients. Hamartomatous polyps showed varied histology, including lymphoid aggregates in 55% of patients, a lipomatous component in 52%, a ganglioneuromatous component in 52%, and a fibrous-rich component in 14%. Polyps with at least two different stromal components were found in 55% of patients. Inflammatory polyps were present in 21% of patients. Conventional adenomas and serrated polyps were identified in 48% and 62% of patients, respectively. In the upper gastrointestinal tract, the most common lesions were esophageal glycogenic acanthosis (37%), gastric hamartomatous polyps (47%), and duodenal hamartomatous polyps (20%). All patients with glycogenic acanthosis who had a colonoscopy had hamartomatous polyps of the large bowel. In five patients, the diagnosis of Cowden syndrome was established after the pathology report raised suspicion for the diagnosis. Pathologists who are aware of the characteristic admixture of lesions in Cowden syndrome can play an essential role in recommending referral to genetic counseling and gene testing. Early diagnosis of Cowden syndrome is important, as these patients and their relatives are at increased risk for developing multiple cancers.

Revisiting PI3-kinase signalling in angiogenesis

PI3Ks belong to a family of lipid kinases that comprises eight isoforms. They phosphorylate the third position of the inositol ring present in phosphatidylinositol lipids and, in turn, activate a broad range of proteins. The PI3K pathway regulates primal cellular responses, including proliferation, migration, metabolism and vesicular traffic. These processes are fundamental for endothelial cell function during sprouting angiogenesis, the most common type of blood vessel formation. Research in animal models has revealed key functions of PI3K family members and downstream effectors in angiogenesis. In addition, perturbations in PI3K signalling have been associated with aberrant vascular growth including tumour angiogenesis and vascular malformations. Together, this highlights that endothelial cells are uniquely sensitive to fluctuations in PI3K signalling. Here, we aim to update the current view on this important signalling cue in physiological and pathological blood vessel growth.

Identification of two novel breast cancer loci through large-scale genome-wide association study in the Japanese population

Genome-wide association studies (GWAS) have successfully identified about 70 genomic loci associated with breast cancer. Owing to the complexity of linkage disequilibrium and environmental exposures in different populations, it is essential to perform regional GWAS for better risk prediction. This study aimed to investigate the genetic architecture and to assess common genetic risk model of breast cancer with 6,669 breast cancer patients and 21,930 female controls in the Japanese population. This GWAS identified 11 genomic loci that surpass genome-wide significance threshold of P < 5.0 × 10⁻⁸ with nine previously reported loci and two novel loci that include rs9862599 on 3q13.11 (ALCAM) and rs75286142 on 21q22.12 (CLIC6-RUNX1). Validation study was carried out with 981 breast cancer cases and 1,394 controls from the Aichi Cancer Center. Pathway analyses of GWAS signals identified association of dopamine receptor medicated signaling and protein amino acid deacetylation with breast cancer. Weighted genetic risk score showed that individuals who were categorized in the highest risk group are approximately 3.7 times more likely to develop breast cancer compared to individuals in the lowest risk group. This well-powered GWAS is a representative study to identify SNPs that are associated with breast cancer in the Japanese population.

PI3K/mTOR Pathway Inhibition: Opportunities in Oncology and Rare Genetic Diseases

The phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) signaling pathway has been implicated as a cancer target. Big pharma players and small companies have been developing small molecule inhibitors of PI3K and/or mTOR since the 1990s. Although four inhibitors have been approved, many open questions regarding tolerability, patient selection, sensitivity markers, development of resistances, and toxicological challenges still need to be addressed. Besides clear oncological indications, PI3K and mTOR inhibitors have been suggested for treating a plethora of different diseases. In particular, genetically induced PI3K/mTOR pathway activation causes rare disorders, known as overgrowth syndromes, like PTEN (phosphatase and tensin homolog) hamartomas, tuberous sclerosis complex (TSC), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-related overgrowth spectrum (PROS), and activated PI3-Kinase delta syndrome (PI3KCD, APDS). Some of those disorders likeTSC or hemimegalencephaly, which are one of the PROS disorders, also belong to a group of diseases called mTORopathies. This group of syndromes presents with additional neurological manifestations associated with epilepsy and other neuropsychiatric symptoms induced by neuronal mTOR pathway hyperactivation. While PI3K and mTOR inhibitors have been and still are intensively tested in oncology indications, their use in genetically defined syndromes and mTORopathies appear to be promising avenues for a pharmacological intervention.

Influencers on Thyroid Cancer Onset: Molecular Genetic Basis

Thyroid cancer, a cancerous tumor or growth located within the thyroid gland, is the most common endocrine cancer. It is one of the few cancers whereby incidence rates have increased in recent years. It occurs in all age groups, from children through to seniors. Most studies are focused on dissecting its genetic basis, since our current knowledge of the genetic background of the different forms of thyroid cancer is far from complete, which poses a challenge for diagnosis and prognosis of the disease. In this review, we describe prevailing advances and update our understanding of the molecular genetics of thyroid cancer, focusing on the main genes related with the pathology, including the different noncoding RNAs associated with the disease.

The Mechanisms Underlying PTEN Loss in Human Tumors Suggest Potential Therapeutic Opportunities

In this review, we will first briefly describe the diverse molecular mechanisms associated with PTEN loss of function in cancer. We will then proceed to discuss the molecular mechanisms linking PTEN loss to PI3K activation and demonstrate how these mechanisms suggest possible therapeutic approaches for patients with PTEN-null tumors.

High-throughput transcriptome analysis reveals that the loss of Pten activates a novel NKX6-1/RASGRP1 regulatory module to rescue microphthalmia caused by Fgfr2-deficient lenses

FGFR signaling is critical to development and disease pathogenesis, initiating phosphorylation-driven signaling cascades, notably the RAS-RAF-MEK-ERK and PI3 K-AKT cascades. PTEN antagonizes FGFR signaling by reducing AKT and ERK activation. Mouse lenses lacking FGFR2 exhibit microphakia and reduced ERK and AKT phosphorylation, widespread apoptosis, and defective lens fiber cell differentiation. In contrast, simultaneous deletion of both Fgfr2 and Pten restores ERK and AKT activation levels as well as lens size, cell survival and aspects of fiber cell differentiation; however, the molecular basis of this "rescue" remains undefined. We performed transcriptomic analysis by RNA sequencing of mouse lenses with conditional deletion of Fgfr2, Pten or both Fgfr2 and Pten, which reveal new molecular mechanisms that uncover how FGFR2 and PTEN signaling interact during development. The FGFR2-deficient lens transcriptome demonstrates overall loss of fiber cell identity with deregulated expression of 1448 genes. We find that ~ 60% of deregulated genes return to normal expression levels in lenses lacking both Fgfr2 and Pten. Further, application of customized filtering parameters to these RNA-seq data sets identified 68 high-priority candidate genes. Bioinformatics analyses showed that the cis-binding motif of a high-priority homeodomain transcription factor, NKX6-1, was present in the putative promoters of ~ 78% of these candidates. Finally, biochemical reporter assays demonstrate that NKX6-1 activated the expression of the high-priority candidate Rasgrp1, a RAS-activating protein. Together, these data define a novel regulatory module in which NKX6-1 directly activates Rasgrp1 expression to restore the balance of ERK and AKT activation, thus providing new insights into alternate regulation of FGFR downstream events.

The Impact of Genetic Variants on PTEN Molecular Functions and Cellular Phenotypes

Phosphatase and tensin homolog (PTEN) is a tumor suppressor that directly regulates a diverse array of cellular phenotypes, including growth, migration, morphology, and genome stability. How a single protein impacts so many important cellular processes remains a fascinating question. This question has been partially resolved by the characterization of a slew of missense variants that alter or eliminate PTEN's various molecular functions, including its enzymatic activity, subcellular localization, and posttranslational modifications. Here, we review what is known about how PTEN variants impact molecular function and, consequently, cellular phenotype. In particular, we highlight eight informative "sentinel variants" that abrogate distinct molecular functions of PTEN. We consider two published massively parallel assays of variant effect that measured the effect of thousands of PTEN variants on protein abundance and enzymatic activity. Finally, we discuss how characterization of clinically ascertained variants, establishment of clinical sequencing databases, and massively parallel assays of variant effect yield complementary datasets for dissecting PTEN's role in disease.

Germline variants associated with leukocyte genes predict tumor recurrence in breast cancer patients

Germline variants such as BRCA1/2 play an important role in tumorigenesis and clinical outcomes of cancer patients. However, only a small fraction (i.e., 5-10%) of inherited variants has been associated with clinical outcomes (e.g., BRCA1/2, APC, TP53, PTEN and so on). The challenge remains in using these inherited germline variants to predict clinical outcomes of cancer patient population. In an attempt to solve this issue, we applied our recently developed algorithm, eTumorMetastasis, which constructs predictive models, on exome sequencing data to ER+ breast (n = 755) cancer patients. Gene signatures derived from the genes containing functionally germline variants significantly distinguished recurred and non-recurred patients in two ER+ breast cancer independent cohorts (n = 200 and 295, P = 1.4 × 10-3). Furthermore, we compared our results with the widely known Oncotype DX test (i.e., Oncotype DX breast cancer recurrence score) and outperformed prediction for both high- and low-risk groups. Finally, we found that recurred patients possessed a higher rate of germline variants. In addition, the inherited germline variants from these gene signatures were predominately enriched in T cell function, antigen presentation, and cytokine interactions, likely impairing the adaptive and innate immune response thus favoring a pro-tumorigenic environment. Hence, germline genomic information could be used for developing non-invasive genomic tests for predicting patients' outcomes in breast cancer.

Decreased breast cancer-specific mortality risk in patients with a history of thyroid cancer

Previous studies have documented an intrinsic association between breast cancer (BC) and thyroid cancer (TC), but the clinical relevance of this relationship is not well defined. In the present study, we specifically investigated the impact of a history of TC on clinical outcomes of BC. We performed a population-based comparative analysis of tumor behaviors and BC-specific mortalities in 427,893 female patients with BC in the USA Surveillance, Epidemiology and End Results 9 database (1973–2013). In this cohort of subjects, 2,569 patients also had a history of differentiated TC (BC/TC), including BC diagnosed before TC (BC-1st) and BC diagnosed after TC (TC-1st), with the median follow-up time of 81 (IQR, 33–160) months. We found that, compared with matched BC-only patients, less aggressive BC tumor behaviors occurred in BC/TC patients, as exemplified by a distant metastasis rate of 7.0% in the former versus 3.3% in the latter (P<0.001). In BC/TC, BC-1st, and TC-1st patients versus their matched BC-only patients, BC-specific mortalities were 11.3% versus 21.0%, 9.9% versus 26.4%, and 12.4% versus 16.9%. These corresponded to hazard ratios (HR) (95% CI) of 0.47 (0.42–0.53), 0.31 (0.26–0.37), and 0.72 (0.61–0.84), respectively (all P<0.001), being lowest in BC-1st patients <50 years old [HR = 0.22 (0.16–0.31)], which remained significant after adjustment for clinicopathological and socioeconomic factors. Estrogen/progesterone receptor expression in BC tumors was significantly higher in patients with BC/TC than matched BC-only patients, providing evidence that BC in the former was biologically unique. Thus, a history of TC, particularly in younger BC-1st patients, may identify BC as a unique disease entity characterized by a decreased disease-specific mortality risk. The results have potentially important clinical and biological implications for BC in this special patient population and encourage further studies to confirm.

Distinct Alterations in Tricarboxylic Acid Cycle Metabolites Associate with Cancer and Autism Phenotypes in Cowden Syndrome and Bannayan-Riley-Ruvalcaba Syndrome

Germline heterozygous PTEN mutations cause subsets of Cowden syndrome (CS) and Bannayan-Riley-Ruvalcaba syndrome (BRRS); these subsets are characterized by high risks of breast, thyroid, and other cancers and, in one subset, autism spectrum disorder (ASD). Up to 10% of individuals with PTEN^MUT CS, CS-like syndrome, or BRRS have germline SDHx (succinate dehydrogenase, mitochondrial complex II) variants, which modify cancer risk. PTEN contributes to metabolic reprogramming; this is a well-established role in a cancer context. Relatedly, SDH sits at the crossroad of the electron transport chain and tricarboxylic acid (TCA) cycle, two central bioenergetic pathways. Intriguingly, PTEN^MUT and SDH^MUT individuals have reduced SDH catalytic activity, resulting in succinate accumulation; this indicates a common genotype-independent biochemical alteration. Here, we conducted a TCA targeted metabolomics study on 511 individuals with CS, CS-like syndrome, or BRRS with various genotypes (PTEN or SDHx, mutant or wild type [WT]) and phenotypes (cancer or ASD) and a series of 187 population controls. We found consistent TCA cycle metabolite alterations in cases with various genotypes and phenotypes compared to controls, and we found unique correlations of individual metabolites with particular genotype-phenotype combinations. Notably, increased isocitrate (p = 1.2 × 10⁻³), but reduced citrate (p = 5.0 × 10⁻⁴), were found to be associated with breast cancer in individuals with PTEN^MUT/SDHx^WT. Conversely, increased lactate was associated with neurodevelopmental disorders regardless of genotype (p = 9.7 × 10⁻³); this finding was replicated in an independent validation series (n = 171) enriched for idiopathic ASD (PTEN^WT, p = 5.6 × 10⁻⁴). Importantly, we identified fumarate (p = 1.9 × 10⁻²) as a pertinent metabolite, distinguishing individuals who develop ASD from those who develop cancer. Our observations suggest that TCA cycle metabolite alterations are germane to the pathobiology of PTEN-related CS and BRRS, as well as genotype-independent ASD, with implications for potential biomarker and/or therapeutic value.

PTEN in the Stroma

Although tremendous progress has been made in understanding the functions of Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in tumor cells, only recently have tumor cell-non-autonomous PTEN actions within the tumor microenvironment (TME) been appreciated. While it is accepted that the TME actively communicates with cancer cells to influence disease progression, our understanding of the genes and pathways responsible is still evolving. Given that inactivation of PTEN in the stroma is correlated with worse outcomes in human cancers, determining the unique functions and mechanisms of PTEN regulation in various TME cell compartments is essential. In this review, the evidence for PTEN function in different TME cell compartments, the mechanisms governing PTEN inactivation, and the downstream pathways regulated by PTEN that are critical for intracellular communication, are covered. The potential clinical implications of these findings as well as the future directions for the study of stromal PTEN are discussed.

The Functional Role of SEC23 in Vesicle Transportation, Autophagy and Cancer

SEC23, the core component of the coat protein complex II (COPII), functions to transport newly synthesized proteins and lipids from the endoplasmic reticulum (ER) to the Golgi apparatus in cells for secretion. SEC23 protein has two isoforms (SEC23A and SEC23B) and their aberrant expression and mutations were reported to cause human diseases and oncogenesis, whereas SEC23A and SEC23B may have the opposite activity in human cancer, for a reason that remains unclear. This review summarizes recent research in SEC23, COPII-vesicle transportation, autophagy, and cancer.

PTEN Suppresses Glycolysis by Dephosphorylating and Inhibiting Autophosphorylated PGK1

The PTEN tumor suppressor is frequently mutated or deleted in cancer and regulates glucose metabolism through the PI3K-AKT pathway. However, whether PTEN directly regulates glycolysis in tumor cells is unclear. We demonstrate here that PTEN directly interacts with phosphoglycerate kinase 1 (PGK1). PGK1 functions not only as a glycolytic enzyme but also as a protein kinase intermolecularly autophosphorylating itself at Y324 for activation. The protein phosphatase activity of PTEN dephosphorylates and inhibits autophosphorylated PGK1, thereby inhibiting glycolysis, ATP production, and brain tumor cell proliferation. In addition, knockin expression of a PGK1 Y324F mutant inhibits brain tumor formation. Analyses of human glioblastoma specimens reveals that PGK1 Y324 phosphorylation levels inversely correlate with PTEN expression status and are positively associated with poor prognosis in glioblastoma patients. This work highlights the instrumental role of PGK1 autophosphorylation in its activation and PTEN protein phosphatase activity in governing glycolysis and tumorigenesis.

Translation deregulation in human disease

Advances in sequencing and high-throughput techniques have provided an unprecedented opportunity to interrogate human diseases on a genome-wide scale. The list of disease-causing mutations is expanding rapidly, and mutations affecting mRNA translation are no exception. Translation (protein synthesis) is one of the most complex processes in the cell. The orchestrated action of ribosomes, tRNAs and numerous translation factors decodes the information contained in mRNA into a polypeptide chain. The intricate nature of this process renders it susceptible to deregulation at multiple levels. In this Review, we summarize current evidence of translation deregulation in human diseases other than cancer. We discuss translation-related diseases on the basis of the molecular aberration that underpins their pathogenesis (including tRNA dysfunction, ribosomopathies, deregulation of the integrated stress response and deregulation of the mTOR pathway) and describe how deregulation of translation generates the phenotypic variability observed in these disorders.

Megalencephaly syndromes associated with mutations of core components of the PI3K-AKT-MTOR pathway: PIK3CA, PIK3R2, AKT3, and MTOR

Megalencephaly (MEG) is a developmental abnormality of brain growth characterized by early onset, often progressive, brain overgrowth. Focal forms of megalencephaly associated with cortical dysplasia, such as hemimegalencephaly and focal cortical dysplasia, are common causes of focal intractable epilepsy in children. The increasing use of high throughput sequencing methods, including high depth sequencing to more accurately detect and quantify mosaic mutations, has allowed us to identify the molecular etiologies of many MEG syndromes, including most notably the PI3K-AKT-MTOR related MEG disorders. Thorough molecular and clinical characterization of affected individuals further allow us to derive preliminary genotype-phenotype correlations depending on the gene, mutation, level of mosaicism, and tissue distribution. Our review of published data on these disorders so far shows that mildly activating variants (that are typically constitutional or germline) are associated with diffuse megalencephaly with intellectual disability and/or autism spectrum disorder; moderately activating variants (that are typically high-level mosaic) are associated with megalencephaly with pigmentary abnormalities of the skin; and strongly activating variants (that are usually very low-level mosaic) are associated with focal brain malformations including hemimegalencephaly and focal cortical dysplasia. Accurate molecular diagnosis of these disorders is undoubtedly crucial to more optimally treat children with these disorders using PI3K-AKT-MTOR pathway inhibitors.

The Clinical Spectrum of PTEN Mutations

PTEN is a tumor suppressor gene that classically dampens the PI3K/AKT/mTOR growth-promoting signaling cascade. PTEN dysfunction causes dysregulation of this and other pathways, resulting in overgrowth. Cowden syndrome, a hereditary cancer predisposition and overgrowth disorder, was the first Mendelian condition associated with germline PTEN mutations. Since then, significant advances by the research and medical communities have elucidated how clinical phenotypic manifestations result from the underlying germline PTEN mutations. With time, it became evident that PTEN mutations can result in a broad phenotypic spectrum, causing seemingly disparate disorders from cancer to autism. Hence, the umbrella term of PTEN hamartoma tumor syndrome (PHTS) was coined. Timely diagnosis and understanding the natural history of PHTS are vital because early recognition enables gene-informed management, particularly as related to high-risk cancer surveillance and addressing the neurodevelopmental symptoms.

Whole exome sequencing in childhood-onset lupus frequently detects single gene etiologies

BACKGROUND

Systemic lupus erythematosus (SLE) comprise a diverse range of clinical manifestations. To date, more than 30 single gene causes of lupus/lupus like syndromes in humans have been identified. In the clinical setting, identifying the underlying molecular diagnosis is challenging due to phenotypic and genetic heterogeneity.

METHODS

We employed whole exome sequencing (WES) in patients presenting with childhood-onset lupus with severe and/or atypical presentations to identify cases that are explained by a single-gene (monogenic) cause.

RESULTS

From January 2015 to June 2018 15 new cases of childhood-onset SLE were diagnosed in Edmond and Lily Safra Children's Hospital. By WES we identified causative mutations in four subjects in five different genes: C1QC, SLC7A7, MAN2B1, PTEN and STAT1. No molecular diagnoses were established on clinical grounds prior to genetic testing.

CONCLUSIONS

We identified a significant fraction of monogenic SLE etiologies using WES and confirm the genetic locus heterogeneity in childhood-onset lupus. These results highlight the importance of establishing a genetic diagnosis for children with severe or atypical lupus by providing accurate and early etiology-based diagnoses and improving subsequent clinical management.

Targeting the PI3-kinase pathway in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is characterised by poor outcomes and a historical lack of targeted therapies. Dysregulation of signalling through the phosphoinositide 3 (PI3)-kinase and AKT signalling pathway is one of the most frequent oncogenic aberrations of TNBC. Although mutations in individual genes occur relatively rarely, combined activating mutations in PIK3CA and AKT1, with inactivating mutations in phosphatase and tensin homologue, occur in ∼25%‒30% of advanced TNBC. Recent randomised trials suggest improved progression-free survival (PFS) with AKT-inhibitors in combination with first-line chemotherapy for patients with TNBC and pathway genetic aberrations. We review the evidence for PI3K pathway activation in TNBC, and clinical trial data for PI3K, AKT and mammalian target of rapamycin inhibitors in TNBC. We discuss uncertainty over defining which cancers have pathway activation and the future overlap between immunotherapy and pathway targeting.

PTEN Hamartoma Tumor Syndrome: A Clinical Overview

The phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is a grouping of related genetic disorders that has been linked to germline mutations in the PTEN gene. These disorders include Cowden syndrome (CS), Bannayan–Riley–Ruvalcaba syndrome, adult Lhermitte–Duclos disease, and autism spectrum disorders associated with macrocephaly. The majority of the clinical information available on PHTS, however, is related to individuals diagnosed with CS. There is still much to be learned about this disorder, since diagnostic criteria for CS were only established in 1996, before the identification of the PTEN gene, and were based primarily on features seen in cases reported in the existing literature. More recently, however, data from several large series of patients have shown that a number of the clinical features associated with PTEN mutations are either more or less common than previously reported. In addition, we now know that only about 30–35% of patients meeting clinical diagnostic criteria for Cowden syndrome actually have a detectable PTEN mutation. Thus, our understanding of PTEN-related diseases and their management has evolved significantly over time. The United States National Comprehensive Cancer Network (NCCN) has produced and regularly updates practice guidelines which include clinical diagnostic criteria as well as guidelines for PTEN testing and management of patients with mutations. This review will summarize the overall literature on PHTS as well as recent findings which are broadening our understanding of this set of disorders.

Phospho Tensin Homolog in Human and Lipid Peroxides in Peripheral Blood Mononuclear Cells Following Exposure to Flavonoids

Objectives: Studies have shown that human and peripheral blood mononuclear cells (PBMCs) are mostly used for research purposes to study several biochemical endpoints. The effects of the flavonoids, genistein, kaempferol, and quercetin on phospho tensin homolog (PTEN) levels in cancer cells (i.e., breast [BT549], lung [A549]), human embryonic kidney cells (HEK293), and the levels of lipid peroxides (LP) in PBMCs were respectively investigated.Materials and methods: Cancer, kidney, and PBMCs from several donors were each exposed to each of the flavonoids at concentrations of 0, 5, 10, 15, 20, and 25 µM. Our hypotheses were that exposure of cancer and kidney cells to genistein, kaempferol, and quercetin can increase PTEN and decrease lipid peroxides in PBMCs levels respectively to better cope with oxidative stress.Results: The results indicate that the flavonoids increased total PTEN levels in a dose-dependent manner. The effect of quercetin was more pronounced followed by genistein and kaempferol. Furthermore, decreases in lipid peroxides were observed in the PBMCs for the flavonoid-treated samples compared to those exposed to flavonoids and with oxidative stress as described by Fenton's chemistry. Levels of LP in quercetin-treated samples were lower compared to kaempferol and genistein.Conclusions: The findings suggest that the flavonoids play an important role in controlling oxidative stress in several human cells.

[Hereditary cutaneous tumor syndromes]

Skin tumors can manifest solitarily and sporadically but can also be multiple and familial. Beside the skin, hereditary cutaneous tumor syndromes also affect extracutaneous organs and are clinically and genetically heterogeneous. Taking the medical history, a clinical examination and dermatopathological characterization of the respective neoplasia will help the dermatologist to reach a diagnosis at an early stage. Subsequently, this diagnosis can be unambiguously confirmed by molecular genetic analysis. Here, we provide an overview and update on selected hereditary cutaneous tumor syndromes.

Looking for the hidden mutation: Bannayan-Riley-Ruvalcaba syndrome caused by constitutional and mosaic 10q23 microdeletions involving PTEN and BMPR1A

The PTEN hamartoma tumor syndrome (PHTS) is caused by heterozygous germline variants in PTEN. Here, we report two unrelated patients with juvenile polyposis, macrocephaly, intellectual disability, and hyperpigmented skin macules. Both patients were clinically suspected for the Bannayan-Riley-Ruvalcaba syndrome (BRRS), a PHTS subentity. By array-CGH analysis, we identified an interstitial 10q23.1q23.3 deletion in a buccal mucosa sample of Patient 1 that encompassed PTEN, BMPR1A, and KLLN, among others. In contrast, neither sequencing nor array-CGH analysis identified a pathogenic variant in PTEN or BMPR1A in a blood sample of Patient 2. However, in a surgical specimen of the thyroid gland high-level mosaicism for a 10q23.2q23.3 deletion was observed. Additionally, the pathogenic PTEN variant c.956_959delCTTT p.(Thr319LysfsTer24) was detected in his thyroid tissue. The frame shift variant was neither detected in the patient's blood nor in his buccal mucosa sample. Low-level mosaicism for the microdeletion was identified in a buccal swap sample, and reanalysis of the blood sample suggested marginal-level mosaicism for deletion. The 10q23.2q23.3 deletion mosaicism was also identified in a subsequently resected colonic polyp. Thus, in both cases, the diagnosis of a 10q23 deletion syndrome, which clinically presented as BRRS, was established. Overall, the study expands the BRRS spectrum and highlights the relevance of considering mosaicism in PHTS. We conclude that in all patients with a clear clinical suspicion of PHTS, in which genetic analyses of DNA from blood and buccal swap samples fail to identify causative genetic variants, genetic analyses of additional tissues are recommended.

Conformational Dynamics and Allosteric Regulation Landscapes of Germline PTEN Mutations Associated with Autism Compared to Those Associated with Cancer

Individuals with germline PTEN tumor-suppressor variants have PTEN hamartoma tumor syndrome (PHTS). Clinically, PHTS has variable presentations; there are distinct subsets of PHTS-affected individuals, such as those diagnosed with autism spectrum disorder (ASD) or cancer. It remains unclear why mutations in one gene can lead to such seemingly disparate phenotypes. Therefore, we sought to determine whether it is possible to predict a given PHTS-affected individual's a priori risk of ASD, cancer, or the co-occurrence of both phenotypes. By integrating network proximity analysis performed on the human interactome, molecular simulations, and residue-interaction networks, we demonstrate the role of conformational dynamics in the structural communication and long-range allosteric regulation of germline PTEN variants associated with ASD or cancer. We show that the PTEN interactome shares significant overlap with the ASD and cancer interactomes, providing network-based evidence that PTEN is a crucial player in the biology of both disorders. Importantly, this finding suggests that a germline PTEN variant might perturb the ASD or cancer networks differently, thus favoring one disease outcome at any one time. Furthermore, protein-dynamic structural-network analysis reveals small-world structural communication mediated by highly conserved functional residues and potential allosteric regulation of PTEN. We identified a salient structural-communication pathway that extends across the inter-domain interface for cancer-only mutations. In contrast, the structural-communication pathway is predominantly restricted to the phosphatase domain for ASD-only mutations. Our integrative approach supports the prediction and potential modulation of the relevant conformational states that influence structural communication and long-range perturbations associated with mutational effects that lead to PTEN-ASD or PTEN-cancer phenotypes.

Recent advances of therapeutic targets based on the molecular signature in breast cancer: genetic mutations and implications for current treatment paradigms

Breast cancer is the most common malignancy in women all over the world. Genetic background of women contributes to her risk of having breast cancer. Certain inherited DNA mutations can dramatically increase the risk of developing certain cancers and are responsible for many of the cancers that run in some families. Regarding the widespread multigene panels, whole exome sequencing is capable of providing the evaluation of genetic function mutations for development novel strategy in clinical trials. Targeting the mutant proteins involved in breast cancer can be an effective therapeutic approach for developing novel drugs. This systematic review discusses gene mutations linked to breast cancer, focusing on signaling pathways that are being targeted with investigational therapeutic strategies, where clinical trials could be potentially initiated in the future are being highlighted.

Association of Single-Nucleotide Polymorphisms in Monoubiquitinated FANCD2-DNA Damage Repair Pathway Genes With Breast Cancer in the Chinese Population

Objective:

The aim of the study was to estimate breast cancer risk conferred by individual single-nucleotide polymorphisms of breast cancer susceptibility genes.

Methods:

We analyzed the 48 tagging single-nucleotide polymorphisms of 8 breast cancer susceptibility genes involved in the monoubiquitinated FANCD2–DNA damage repair pathway in 734 Chinese women with breast cancer and 672 age-matched healthy controls.

Results:

Forty-five tagging single-nucleotide polymorphisms were successfully genotyped by SNPscan, and the call rates for each tagging single-nucleotide polymorphisms were above 98.9%. We found that 13 tagging single-nucleotide polymorphisms of 5 genes (Parter and localizer of Breast cancer gene2 (PALB2), Tumour protein 53 (TP53), Nijmegen breakage syndrome 1, Phosphatase and tensin homolog deleted from chromosome 10 (PTEN), and Breast cancer gene 1 (BRCA1-interacting protein 1)) were significantly associated with breast cancer risk. A total of 5 tagging single-nucleotide polymorphisms (rs2299941 of PTEN, rs2735385, rs6999227, rs1805812, and rs1061302 of Nijmegen breakage syndrome 1) were tightly associated with breast cancer risk in sporadic cases, and 5 other tagging single-nucleotide polymorphisms (rs1042522 of TP53, rs2735343 of PTEN, rs7220719, rs16945628, and rs11871753 of BRCA1-interacting protein 1) were tightly associated with breast cancer risk in familial and early-onset cases.

Conclusions:

Some of the tagging single-nucleotide polymorphisms of 5 genes (PALB2, TP53, Nijmegen breakage syndrome 1, PTEN, and BRCA1-interacting protein 1) involved in the monoubiquitinated FANCD2–DNA damage repair pathway were significantly associated with breast cancer risk.

Phosphoinositide phosphatases in cancer cell dynamics-Beyond PI3K and PTEN

Phosphoinositides are a group of lipids that regulate intracellular signaling and subcellular biological events. The signaling by phosphatidylinositol-3,4,5-trisphosphate and Akt mediates the action of growth factors that are essential for cell proliferation, gene transcription, cell migration, and polarity. The hyperactivation of this signaling has been identified in different cancer cells; and, it has been implicated in oncogenic transformation and cancer cell malignancy. Recent studies have argued the role of phosphoinositides in cancer cell dynamics, including actin cytoskeletal rearrangement at the plasma membrane and the organization of intracellular compartments. The focus of this review is to summarize the impact of the activities of phosphoinositide phosphatases on intracellular signaling related to cancer cell dynamics and to discuss how the abnormalities in the activities of the enzymes alter the levels of phosphoinositides in cancer cells.

PTEN arginine methylation by PRMT6 suppresses PI3K-AKT signaling and modulates pre-mRNA splicing

Arginine methylation is a ubiquitous posttranslational modification that regulates critical cellular processes including signal transduction and pre-mRNA splicing. Here, we report that the tumor-suppressor PTEN is methylated by protein arginine methyltransferase 6 (PRMT6). Mass-spectrometry analysis reveals that PTEN is dimethylated at arginine 159 (R159). We found that PTEN is mutated at R159 in cancers, and the PTEN mutant R159K loses its capability to inhibit the PI3K-AKT cascade. Furthermore, PRMT6 is physically associated with PTEN, promotes asymmetrical dimethylation of PTEN, and regulates the PI3K-AKT cascade through PTEN R159 methylation. In addition, using transcriptome analyses, we found that PTEN R159 methylation is involved in modulation of pre-mRNA alternative splicing. Our results demonstrate that PTEN is functionally regulated by arginine methylation. We propose that PTEN arginine methylation modulates pre-mRNA alternative splicing and influences diverse physiologic processes.

Integrated Analysis of Germline and Tumor DNA Identifies New Candidate Genes Involved in Familial Colorectal Cancer

Colorectal cancer (CRC) shows aggregation in some families but no alterations in the known hereditary CRC genes. We aimed to identify new candidate genes which are potentially involved in germline predisposition to familial CRC. An integrated analysis of germline and tumor whole-exome sequencing data was performed in 18 unrelated CRC families. Deleterious single nucleotide variants (SNV), short insertions and deletions (indels), copy number variants (CNVs) and loss of heterozygosity (LOH) were assessed as candidates for first germline or second somatic hits. Candidate tumor suppressor genes were selected when alterations were detected in both germline and somatic DNA, fulfilling Knudson's two-hit hypothesis. Somatic mutational profiling and signature analysis were also performed. A series of germline-somatic variant pairs were detected. In all cases, the first hit was presented as a rare SNV/indel, whereas the second hit was either a different SNV (3 genes) or LOH affecting the same gene (141 genes). BRCA2, BLM, ERCC2, RECQL, REV3L and RIF1 were among the most promising candidate genes for germline CRC predisposition. The identification of new candidate genes involved in familial CRC could be achieved by our integrated analysis. Further functional studies and replication in additional cohorts are required to confirm the selected candidates.

Surgical management of follicular thyroid carcinoma in children and adolescents: A study of 30 cases

BACKGROUND/PURPOSE

The purpose of the study is to describe the anatomoclinical, diagnostic, therapeutic and prognostic aspects of pediatric follicular thyroid carcinoma (FTC) in order to choose the best therapeutic strategy.

METHODS

Our study includes patients ≤18 years old surgically treated for FTC in four Italian Pediatric Surgery Centers from January 2000 to March 2017. The collected data were compared with those of 132 patients matched for age with a histological diagnosis of papillary thyroid carcinoma (PTC) surgically treated in the same institutions during the same period and with the data of patients diagnosed with FTC found in the literature; p-values <0.05 were considered significant.

RESULTS

21 (70%) of the 30 patients with a histological diagnosis of FTC underwent hemithyroidectomy while 9 (30%) underwent total thyroidectomy. 11 (55%) out of 21 patients were subjected to a completion of thyroidectomy. All patients are alive (OS = 100%) without recurrence or relapse of the disease. Compared with PTC, FTC is significant for capsule infiltration (p < 0.0001), vascular invasion (p = 0.0014) and T-stage T3-T4 (p = 0.013). However, multifocality (p < 0.001), extrathyroid extension (p < 0.0001) and lymph node metastasis (p < 0.0001) are more evident in PTC.

CONCLUSION

The conservative approach seems to be a valid surgical treatment for pediatric patients diagnosed with MI-FTC. For patients with wide vascular invasion and/or a tumor >4 cm, especially with high after-surgery Tg rate, a completion of thyroidectomy is recommended. In patients with multifocal neoplasia, and/or tumor size ≥4 cm, and/or extrathyroid extension, and/or lymph node metastasis, and/or distant metastasis, total thyroidectomy followed by radioiodine therapy is generally indicated.

LEVELS OF EVIDENCE

II.