A novel deleterious PTEN mutation in a patient with early-onset bilateral breast cancer

The Association of PTEN Gene Mutations with the Breast Cancer Risk: A Systematic Review and Meta-analysis

Breast cancer (BC) is the most common malignancy in women in western countries. A significant part of malignant cases is caused by genetic mutation. Mutations in the gene phosphatase and tensin homologue deleted on chromosome (PTEN) have been proven in various malignancies. The present study was conducted with the aim of investigating the prevalence of BC due to PTEN gene mutation, as well as estimating the chance of developing BC due to the occurrence of PTEN gene mutation. The present study was conducted using a systematic review method based on PRISMA 2020 statements. The search was done in PubMed, Web of Science (WOS), Scopus, and direct scientific databases. The search was performed using the keywords breast cancer, breast malignancy, PTEN, polymorphism, mutation, variant, and their equivalents. Statistical analysis was performed using the second version of Comprehensive Meta-Analysis Software. A total of 2138 articles were collected. After removing duplicate articles, checking the title and abstract, and then checking the full text of the documents, finally 64 articles were approved and entered the systematic review process. Analysis of these studies with a sample size of 231,179 showed the prevalence of breast cancer patients with PTEN mutations. The combined results of 64 studies showed that the prevalence of PTEN mutations has a 3.3 (95% CI 2.2-5) in BC patients, and an analysis of 6 studies showed that the odds ratio of developing BC due to PTEN mutation is 3.7 (95% CI 1.1-11.9). The results of this study show that mutation in the PTEN gene increases the chance of developing BC. However, it was found that a small part of patients gets BC due to the occurrence of mutation in this gene.

Synchronous and metachronous thyroid cancer, breast cancer, and melanoma in a premenopausal patient with Cowden syndrome

Cowden syndrome is a rare autosomal dominant genetic disorder characterized by a germline mutation in the phosphatase and tensin homolog gene, leading to multiple hamartomas, neurodevelopmental disorders, and an increased lifetime risk of multiple cancers. Malignancy is the most common cause of mortality in Cowden syndrome, with breast cancer being the most common malignancy encountered in females with the disorder. Screening guidelines for this population should address this risk at an early age. We present a case of metachronous thyroid cancer followed by synchronous breast cancer and melanoma in a young female with Cowden syndrome, highlighting diagnostic imaging, management, and screening considerations.

What Is Known about Breast Cancer in Young Women?

Breast cancer (BC) is the second leading cause of cancer-related death in women under the age of 40 years worldwide. In addition, the incidence of breast cancer in young women (BCYW) has been rising. Young women are not the focus of screening programs and BC in younger women tends to be diagnosed in more advanced stages. Such patients have worse clinical outcomes and treatment complications compared to older patients. BCYW has been associated with distinct tumour biology that confers a worse prognosis, including poor tumour differentiation, increased Ki-67 expression, and more hormone-receptor negative tumours compared to women >50 years of age. Pathogenic variants in cancer predisposition genes such as BRCA1/2 are more common in early-onset BC compared to late-onset BC. Despite all these differences, BCYW remains poorly understood with a gap in research regarding the risk factors, diagnosis, prognosis, and treatment. Age-specific clinical characteristics or outcomes data for young women are lacking, and most of the standard treatments used in this subpopulation currently are derived from older patients. More age-specific clinical data and treatment options are required. In this review, we discuss the epidemiology, clinicopathologic characteristics, outcomes, treatments, and special considerations of breast cancer in young women. We also underline future directions and highlight areas that require more attention in future studies.

Targeting the mTOR Pathway in Hurthle Cell Carcinoma Results in Potent Anti-Tumor Activity

Hurthle cell carcinomas (HCC) are refractory to radioactive iodine and unresponsive to chemotherapeutic agents, with a fatality rate that is the highest among all types of thyroid cancer after anaplastic thyroid cancer. Our previous study on the genomic landscape of HCCs identified a high incidence of disruptions of mTOR pathway effectors. Here, we report a detailed analysis of mTOR signaling in cell line and patient-derived xenograft (PDX) mouse models of HCCs. We show that mTOR signaling is upregulated and that targeting mTOR signaling using mTOR inhibitors suppresses tumor growth in primary tumors and distant metastasis. Mechanistically, ablation of mTOR signaling impaired the expression of p-S6 and cyclin A2, resulting in the decrease of S phase and blocking of cancer cell proliferation. Strikingly, mTOR inhibitor treatment significantly reduced lung metastatic lesions, with the decreased expression of Snail in xenograft tumors. Our data demonstrates that mTOR pathway blockade represents a novel treatment strategy for HCC.

Risks and Function of Breast Cancer Susceptibility Alleles

Family history remains one of the strongest risk factors for breast cancer. It is well established that women with a first-degree relative affected by breast cancer are twice as likely to develop the disease themselves. Twins studies indicate that this is most likely due to shared genetics rather than shared epidemiological/lifestyle risk factors. Linkage and targeted sequencing studies have shown that rare high- and moderate-penetrance germline variants in genes involved in the DNA damage response (DDR) including BRCA1, BRCA2, PALB2, ATM, and TP53 are responsible for a proportion of breast cancer cases. However, breast cancer is a heterogeneous disease, and there is now strong evidence that different risk alleles can predispose to different subtypes of breast cancer. Here, we review the associations between the different genes and subtype-specificity of breast cancer based on the most comprehensive genetic studies published. Genome-wide association studies (GWAS) have also been used to identify an additional hereditary component of breast cancer, and have identified hundreds of common, low-penetrance susceptibility alleles. The combination of these low penetrance risk variants, summed as a polygenic risk score (PRS), can identify individuals across the spectrum of disease risk. However, there remains a substantial bottleneck between the discovery of GWAS-risk variants and their contribution to tumorigenesis mainly because the majority of these variants map to the non-protein coding genome. A range of functional genomic approaches are needed to identify the causal risk variants and target susceptibility genes and establish their underlying role in disease biology. We discuss how the application of these multidisciplinary approaches to understand genetic risk for breast cancer can be used to identify individuals in the population that may benefit from clinical interventions including screening for early detection and prevention, and treatment strategies to reduce breast cancer-related mortalities.

PTEN Hamartoma Tumor Syndrome: Skin Manifestations and Insights Into Their Molecular Pathogenesis

Germline PTEN pathogenic variants cause a spectrum of disorders collectively labeled PTEN Hamartoma Tumor Syndrome (PHTS) and featured by hamartomas, developmental anomalies and increased cancer risk. Studies on experimental models provided evidence that PTEN is a “haploinsufficient” tumor-suppressor gene, however, mechanisms involved in the pathogenesis of clinical manifestations in PHTS patients remain elusive. Beyond analyzing clinical and molecular features of a series of 20 Italian PHTS patients, we performed molecular investigations to explore the mechanisms involved in the pathogenesis of PTEN-associated manifestations, with special focus on mucocutaneous manifestations. Typical mucocutaneous features were present in all patients assessed, confirming that these are the most important clue to the diagnosis. The most frequent were papules located in the trunk or extremities (73.7%), oral mucosa papules (68.4%), acral/palmoplantar keratosis and facial papules (both 57.9%), according with literature data. Molecular analyses on one trichilemmoma suggested that the wild-type PTEN allele was retained and expressed, reinforcing the evidence that PTEN does not require a second somatic hit to initiate pathogenic processes. Unexpectedly, one patient also displayed a cutaneous phenotype consistent with atypical mole/melanoma syndrome; no variants were detected in known melanoma genes, but Whole Exome Sequencing showed the rare truncating variant c.495G>A in the CDH13 gene that might have cooperated with PTEN-haploinsufficiency to generate such phenotype. Our findings confirm the reproducibility of known PHTS manifestations in real-world practice, highlighting the role of mucocutaneous manifestations in facilitating prompt diagnosis of the syndrome, and provide some insights into the pathogenic process induced by PTEN alterations, which may contribute to its understanding.

Rare genetic variants: making the connection with breast cancer susceptibility

The practice of clinical genetics in the context of breast cancer predisposition has reached another critical point in its evolution. For the past two decades, genetic testing offered to women attending clinics has been limited to BRCA1 and BRCA2 unless other syndromic indicators have been evident (e.g. PTEN and TP53 for Cowden and Li-Fraumeni syndrome, respectively). Women (and their families) who are concerned about their personal and/or family history of breast and ovarian cancer have enthusiastically engaged with clinical genetics services, anticipating a genetic cause for their cancer predisposition will be identified and to receive clinical guidance for their risk management and treatment options. Genetic testing laboratories have demonstrated similar enthusiasm for transitioning from single gene to gene panel testing that now provide opportunities for the large number of women found not to carry mutations in BRCA1 and BRCA2, enabling them to undergo additional genetic testing. However, these panel tests have limited clinical utility until more is understood about the cancer risks (if any) associated with the genetic variation observed in the genes included on these panels. New data is urgently needed to improve the interpretation of the genetic variation data that is already reported from these panels and to inform the selection of genes included in gene panel tests in the future. To address this issue, large internationally coordinated research studies are required to provide the evidence-base from which clinical genetics for breast cancer susceptibility can be practiced in the era of gene panel testing and oncogenetic practice.

Two significant steps associated with this process include i) validating the genes on these panels (and those likely to be added in the future) as bona fide1 breast cancer predisposition genes and ii) interpreting the variation, on a variant-by-variant basis in terms of their likely “pathogenicity”—a process commonly referred to as “variant classification” that will enable this new genetic information to be used at an individual level in clinical genetics services. Neither of these fundamental steps have been achieved for the majority of genes included on the panels.

We are thus at a critical point for translational research in breast cancer clinical genetics—how can rare genetic variants be interpreted such that they can be used in clinical genetics services and oncogenetic practice to identify and to inform the management of families that carry these variants?

Potentially pathogenic germline CHEK2 c.319+2T>A among multiple early-onset cancer families

To study the potential contribution of genes other than BRCA1/2, PTEN, and TP53 to the biological and clinical characteristics of multiple early-onset cancers in Norwegian families, including early-onset breast cancer, Cowden-like and Li-Fraumeni-like syndromes (BC, CSL and LFL, respectively). The Hereditary Cancer Biobank from the Norwegian Radium Hospital was used to identify early-onset BC, CSL or LFL for whom no pathogenic variants in BRCA1/2, PTEN, or TP53 had been found in routine diagnostic DNA sequencing. Forty-four cancer susceptibility genes were selected and analyzed by our in-house designed TruSeq amplicon-based assay for targeted sequencing. Protein- and RNA splicing-dedicated in silico analyses were performed for all variants of unknown significance (VUS). Variants predicted as the more likely to affect splicing were experimentally analyzed by minigene assay. We identified a CSL individual carrying a variant in CHEK2 (c.319+2T>A, IVS2), here considered as likely pathogenic. Out of the five VUS (BRCA2, CDH1, CHEK2, MAP3K1, NOTCH3) tested in the minigene splicing assay, only NOTCH3 c.14090C>T (p.Ser497Leu) showed a significant effect on RNA splicing, notably by inducing partial skipping of exon 9. Among 13 early-onset BC, CSL and LFL patients, gene panel sequencing identified a potentially pathogenic variant in CHEK2 that affects a canonical RNA splicing signal. Our study provides new information on genetic loci that may affect the risk of developing cancer in these patients and their families, demonstrating that genes presently not routinely tested in molecular diagnostic settings may be important for capturing cancer predisposition in these families.

Breast cancer genetics in young women: What do we know?

Breast cancer (BC) in young women, generally defined in oncology as women who are 40 years of age or younger, represents 2 out of 10 BC cases in developing countries. Several research studies, including genetic cancer panel tests, genome-wide association studies, expression analyses and polymorphisms reports, have found that young women with BC exhibit a higher genetic susceptibility and specific genomic signature compared to postmenopausal women with BC. Thus, international guidelines recommend genetic counseling for this age population. This review presents the current state of the art of genetics and genomics with regards to young women with BC.

De novo resistance biomarkers to anti-HER2 therapies in HER2-positive breast cancer

Therapies targeting HER2 receptor, overexpressed in 20% breast cancer (BC), improved prognosis, however ~62% patients experiment progression during the first year. Molecular mechanisms proposed to be responsible for this de novo resistance include HER2 modifications, defects in the antibody dependent cellular cytotoxicity or in cell arrest and apoptosis or alterations in HER2 signaling components. This article will review the influence of genetic markers investigated to date as cause of de novo resistance to HER2-targeted drugs in HER2-positive BC patients. Biomarkers like p95HER2, CCND1 and CDC25A have demonstrated clinical relevance and prognostic value in HER2-positive BC patients. However, the prognostic value of most biomarkers investigated to date, such as PIK3CA or AKT1, cannot be fully established yet.

Antagomir-1290 suppresses CD133⁺ cells in non-small cell lung cancer by targeting fyn-related Src family tyrosine kinase

Cancer stem-like cells (CSLCs) are involved in cancer initiation, development, and metastasis, and microRNAs (miRNAs) play pivotal roles in regulating CSLCs. miRNA-based therapeutic strategy associated with CSLCs might promise potential new therapeutic approaches. In the present study, we found that miR-1290 was increased in CD133(+) cells. Antagomir-1290 significantly suppressed tumor volume and weight initiated by CD133(+) cells in vivo. Furthermore, antagomir-1290 significantly inhibited the proliferation, clonogenicity, invasion, and migration of CD133(+) cells by targeting fyn-related Src family tyrosine kinase. These findings provide insights into the clinical prospect of miR-1290-based therapies for non-small cell lung cancer.

Functionally distinct groups of inherited PTEN mutations in autism and tumour syndromes

BACKGROUND

Germline mutations in the phosphatase PTEN are associated with diverse human pathologies, including tumour susceptibility, developmental abnormalities and autism, but any genotype-phenotype relationships are poorly understood.

METHODS

We have studied the functional consequences of seven PTEN mutations identified in patients diagnosed with autism and macrocephaly and five mutations from severe tumour bearing sufferers of PTEN hamartoma tumour syndrome (PHTS).

RESULTS

All seven autism-associated PTEN mutants investigated retained the ability to suppress cellular AKT signalling, although five were highly unstable. Observed effects on AKT also correlated with the ability to suppress soma size and the length and density of dendritic spines in primary neurons. Conversely, all five PTEN mutations from severe cases of PHTS appeared to directly and strongly disrupt the ability to inhibit AKT signalling.

CONCLUSIONS

Our work implies that alleles causing incomplete loss of PTEN function are more commonly linked to autism than to severe PHTS cases.