Phosphatidylinositol-3-kinase α catalytic subunit gene somatic mutations in bronchopulmonary neuroendocrine tumours

Myc family proteins: Molecular drivers of tumorigenesis and resistance in neuroendocrine tumors

Neuroendocrine cancers are a diverse and poorly understood collection of malignancies derived from neuroendocrine cells throughout the body. These cancers uniquely exhibit properties of both the nervous and endocrine systems. Only a limited number of genetic driver mutations have been identified in neuroendocrine cancers, however the mechanisms of how these genetic aberrations alter tumor biology remain elusive. Recent studies have implicated the MYC family of transcription factors as important oncogenic factors in neuroendocrine tumors. We take a systematic approach to understand the roles of the MYC family (c-MYC, n-MYC, l-MYC) in the tumorigenesis of neuroendocrine cancers of the lung, GI tract, pancreas, kidney, prostate, pediatric neuroblastoma, and adrenal glands. Reflecting the complexity of neuroendocrine cancers, we highlight the roles of the MYC family in deregulating the cell cycle and transcriptional networks, invoking cellular plasticity, affecting proliferation capacity, aiding in chromatin remodeling, angiogenesis, metabolic changes, and resistance mechanisms. Depicting the diversity of neuroendocrine cancers, we suggest new approaches in understanding the underlying tumorigenic processes of neuroendocrine cancers from the perspective of MYC.

Concomitant inhibition of PI3K/mTOR signaling pathways boosts antiproliferative effects of lanreotide in bronchopulmonary neuroendocrine tumor cells

Introduction: Somatostatin analogues (SSAs) are commonly used in the treatment of hormone hypersecretion in neuroendocrine tumors (NETs), however the extent to which they inhibit proliferation is much discussed. Objective: We studied the antiproliferative effects of novel SSA lanreotide in bronchopulmonary NETs (BP-NETs). We focused on assessing whether pretreating cells with inhibitors for phosphatidylinositol 3-kinase (PI3K) and mammalian target for rapamycin (mTOR) could enhance the antiproliferative effects of lanreotide. Methods: BP-NET cell lines NCI-H720 and NCI-H727 were treated with PI3K inhibitor BYL719 (alpelisib), mTOR inhibitor everolimus and SSA lanreotide to determine the effect on NET differentiation markers, cell survival, proliferation and alterations in cancer-associated pathways. NT-3 cells, previously reported to express somatostatin receptors (SSTRs) natively, were used as control for SSTR expression. Results: SSTR2 was upregulated in NCI-H720 and NT-3 cells upon treatment with BYL719. Additionally, combination treatment consisting of BYL719 and everolimus plus lanreotide tested in NCI-H720 and NCI-H727 led to diminished cell proliferation in a dose-dependent manner. Production of proteins activating cell death mechanisms was also induced. Notably, a multiplexed gene expression analysis performed on NCI-H720 revealed that BYL719 plus lanreotide had a stronger effect on the downregulation of mitogens than lanreotide alone. Discussion/Conclusion: We report a widespread analysis of changes in BP-NET cell lines at the genetic/protein expression level in response to combination of lanreotide with pretreatment consisting of BYL719 and everolimus. Interestingly, SSTR expression reinduction could be exploited in therapeutic and diagnostic applications. The overall results of this study support the evaluation of combination-based therapies using lanreotide in preclinical studies to further increase its antiproliferative effect and ultimately facilitate its use in high-grade tumors.

Neuroendocrine Neoplasms: Genetics and Epigenetics

Neuroendocrine neoplasms (NENs) are a group of rare, heterogeneous tumors of neuroendocrine cell origin, affecting a range of different organs. The clinical management of NENs poses significant challenges, as tumors are often diagnosed at an advanced stage where overall survival remains poor with current treatment regimens. In addition, a host of complex and often unique molecular changes underpin the pathobiology of each NEN subtype. Exploitation of the unique genetic and epigenetic signatures driving each NEN subtype provides an opportunity to enhance the diagnosis, treatment, and monitoring of NEN in an emerging era of individualized medicine.

Indications for genetic study in gastro-entero-pancreatic and thoracic neuroendocrine tumors

Gastro-entero-pancreatic (GEP-NET) and thoracic neuroendocrine tumours (NETs) are one of the most heritable groups of neoplasms in the body, being multiple endocrine neoplasia syndrome type 1 (MEN1), the genetic syndrome most frequently associated with this type of tumours. Moreover, Von Hippel Lindau syndrome, tuberous sclerosis, type 4 multiple neoplasia syndrome, and type 1 neurofibromatosis are associated with an increased risk of developing GEP-NETs. Another important aspect in GEP-NETs and thoracic NETs is the knowledge of the molecular background since the molecular profile of these tumours may have implications in the prognosis and in the response to specific treatments. This review summarizes the main indications for performing a genetic study in patients with GEP-NETs and thoracic NETs, and the methods used to carry it out. Moreover, it offers a description of the main hereditary syndromes associated with these NETs and their molecular background, as well as the clinical implications of the molecular profile.

PIK3CA mutations in breast cancer: A Tunisian series

BACKGROUND

The aim of this study was to analyze PIK3CA mutations in exons 9 and 20 in breast cancers (BCs) and their association with clinicopathological characteristics.

METHODS

Mutational analysis of PIK3CA exon 9 and 20 was performed by Sanger sequencing in 54 primary BCs of Tunisian women. The associations of PIK3CA mutations with clinicopathological characteristics were analyzed.

RESULTS

Fifteen exon 9 and exon 20 PIK3CA variants were identified in 33/54 cases (61%). PIK3CA mutations including pathogenic (class 5/Tier I) or likely pathogenic (class 4/Tier II) occurred in 24/54 cases (44%): 17/24 cases (71%) in exon 9, 5/24 cases (21%) in exon 20 and 2/24 cases (8%) in both exons. Of these 24 cases, 18 (75%) carried at least one of the three hot spot mutations: E545K (in 8 cases), H1047R (in 4 cases), E542K (in 3 cases), E545K/E542K (in one case), E545K/H1047R (in one case) and P539R/H1047R (in one case). Pathogenic PIK3CA mutations were associated with negative lymph node status (p = 0.027). Age distribution, histological SBR tumor grading, estrogen and progesterone receptors, human epidermal growth factor receptor 2, and molecular classification were not correlated with PIK3CA mutations (p > 0.05).

CONCLUSION

The frequency of somatic PIK3CA mutations in BCs of Tunisian women is slightly higher than that of BCs of Caucasian women and more observed in exon 9 than in exon 20. PIK3CA mutated status is associated with negative lymph node status. These data need to be confirmed in larger series.

Lung Neuroendocrine Tumors: How Does Molecular Profiling Help?

PURPOSE OF REVIEW

Lung neuroendocrine tumors (NETs)-typical carcinoids and atypical carcinoids-have unique molecular alterations that are distinct from neuroendocrine carcinomas of the lung and non-small cell lung cancers. Here, we review the role of molecular profiling in the prognosis and treatment of lung NETs.

RECENT FINDINGS

There have been no recently identified molecular prognostic factors for lung NETs and none that have been routinely used to guide management of patients with lung NETs. Previous findings suggest that patients with loss of chromosome 11q may have a worse prognosis along with upregulation of anti-apoptotic pathways (e.g., loss of CD44 and OTP protein expression). Lung NETs rarely harbor driver mutations commonly found in non-small cell lung cancer (NSCLC) or TP53/RB1 mutations found universally in small cell lung cancer. Lung NETs also have low tumor mutation burden and low PD-L1 expression. Everolimus, an mTOR inhibitor and the only FDA approved therapy for unresectable lung NETs, is an effective treatment but the presence of a molecular alteration in the PI3K/AKT/mTOR pathway is not known to predict treatment response. The predominant mutations in lung NETs occur in genes regulating chromatin remodeling and histone modification, with potential targeted therapies emerging in clinical trials. Lung NETs have recurring alterations in genes that regulate the epigenome. Future targeted therapy interfering with epigenetic pathways may hold promise.

Bronchial Carcinoids: From Molecular Background to Treatment Approach

A better understanding of the genetic and molecular background of bronchial carcinoids (BCs) would allow a better estimation of the risk of disease progression and the personalization of treatment in cases of advanced disease. Molecular studies confirmed that lungs neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) are different entities; thus, no progression of NET to NEC is expected. In BCs, MEN1 gene mutations and deletions and decreased gene expression have been associated with a poor prognosis. ATRX mutation has also been linked to a shorter disease-specific survival. In terms of therapeutic targets, PI3K/AKT/mTOR pathway mutations have been described in 13% of typical carcinoids (TCs) and 39% of atypical carcinoids (ACs), representing a targetable mutation with kinase inhibitors. Regarding treatment, surgical resection is usually curative in localized BCs and adjuvant treatment is not routinely recommended. Multiple options for systemic therapy exist for patients with advanced BCs, although limited by a heterogeneity in the scientific evidence behind their use recommendation. These options include somatostatin analogues, everolimus, peptide receptor radionuclide therapy, chemotherapy, radiotherapy, antiangiogenic agents, and immunotherapy. In this article, we provide a comprehensive review about the molecular and genetic background of BCs, and about the treatment of local and metastatic disease, as well as the main paraneoplastic syndromes that have been associated with this tumor.

Molecular Pathology of Well-Differentiated Pulmonary and Thymic Neuroendocrine Tumors: What Do Pathologists Need to Know?

Thoracic (pulmonary and thymic) neuroendocrine tumors are well-differentiated epithelial neuroendocrine neoplasms that are classified into typical and atypical carcinoid tumors based on mitotic index cut offs and presence or absence of necrosis. This classification scheme is of great prognostic value but designed for surgical specimens, only. Deep molecular characterization of thoracic neuroendocrine tumors highlighted their difference with neuroendocrine carcinomas. Neuroendocrine tumors of the lung are characterized by a low mutational burden, and a high prevalence of mutations in chromatin remodeling and histone modification-related genes, whereas mutations in genes frequently altered in neuroendocrine carcinomas are rare. Molecular profiling divided thymic neuroendocrine tumors into three clusters with distinct clinical outcomes and characterized by a different average of copy number instability. Moreover, integrated histopathological, molecular and clinical evidence supports the existence of a grey zone category between neuroendocrine tumors (carcinoid tumors) and neuroendocrine carcinomas. Indeed, cases with well differentiated morphology but mitotic/Ki-67 indexes close to neuroendocrine carcinomas have been increasingly recognized. These are characterized by specific molecular profiles and have an aggressive clinical behavior. Finally, thoracic neuroendocrine tumors may arise in the background of genetic susceptibility, being MEN1 syndrome the well-defined familial form. However, pathologists should be aware of rarer germline variants that are associated with the concurrence of neuroendocrine tumors of the lung or their precursors (such as DIPNECH) with other neoplasms, including but not limited to breast carcinomas. Therefore, genetic counseling for all young patients with thoracic neuroendocrine neoplasia and/or any patient with pathological evidence of neuroendocrine cell hyperplasia-to-neoplasia progression sequence or multifocal disease should be considered.

Clinicopathological characteristics and genetic analysis of pulmonary carcinoid tumors: A single-center retrospective cohort study and literature review

Pulmonary carcinoid tumors, including typical and atypical carcinoids, are well-differentiated neuroendocrine tumors (NETs) that represent 1–2% of all lung cancer cases. In the present study, all cases of well-differentiated NETs diagnosed at Tianjin Medical University General Hospital (Tianjin, China) between 2006 and 2016 were reviewed, and 20 pulmonary carcinoid cases were identified. The clinical features of these cases were summarized, and the results of pathological and imaging examinations were collated. As a low-grade malignant pulmonary neoplasm, the molecular biological mechanism of pulmonary carcinoids is yet to be elucidated. To investigate the underlying molecular mechanisms behind pulmonary carcinoids and to determine an effective molecular targeted therapeutic strategy, next-generation sequencing (NGS) was performed using tissue samples from six patients to determine additional molecular biological characteristics that may help guide targeted therapy. A total of 27 somatic mutations in 21 genes were detected. Of note, mutations in the KIT proto-oncogene receptor tyrosine kinase, Erb-B2 receptor tyrosine kinase 4, MET proto-oncogene receptor tyrosine kinase and insulin-like growth factor 1 genes occurred in two out of six cases. Since treatments for advanced carcinoids are relatively ineffective, molecular profiling may contribute to the identification of novel treatments. In addition, the literature on mutations in pulmonary carcinoids was reviewed and available clinical information and features of this tumor type were summarized.

New Insights into the Molecular Characteristics of Pulmonary Carcinoids and Large Cell Neuroendocrine Carcinomas, and the Impact on Their Clinical Management

Carcinoids and large cell neuroendocrine carcinomas (LCNECs) are rare neuroendocrine lung tumors. Here we provide an overview of the most updated data on the molecular characteristics of these diseases. Recent genomic studies showed that carcinoids generally contain a low mutational burden and few recurrently mutated genes. Most of the reported mutations occur in chromatin-remodeling genes (e.g., menin 1 gene [MEN1]), and few affect genes of the phosphoinositide 3-kinase (PI3K)-AKT-mechanistic target of rapamycin gene pathway. Aggressive disease has been related to chromothripsis, DNA-repair gene mutations, loss of orthopedia homeobox/CD44, and upregulation of ret proto-oncogene gene (RET) gene expression. In the case of LCNECs, which present with a high mutation burden, two major molecular subtypes have been identified: one with biallelic inactivation of tumor protein p53 gene (TP53) and retinoblastoma gene (RB1), a hallmark of SCLC; and the other one with biallelic inactivation of TP53 and serine/threonine kinase 11 gene (STK11)/kelch like ECH associated protein 1 gene (KEAP1), genes that are frequently mutated in NSCLC. These data, together with the identification of common mutations in the different components of combined LCNEC tumors, provide further evidence of the close molecular relation of LCNEC with other lung tumor types. In terms of therapeutic options, future studies should explore the association between mechanistic target of rapamycin pathway mutations and response to mechanistic target of rapamycin inhibitors in carcinoids. For LCNEC, preliminary data suggest that the two molecular subtypes might have a predictive value for chemotherapy response, but this observation needs to be validated in randomized prospective clinical trials. Finally, delta like Notch canonical ligand 3 inhibitors and immunotherapy may provide alternative options for patient-tailored therapy in LCNEC.

Amiodarone's major metabolite, desethylamiodarone, induces apoptosis in human cervical cancer cells

Previously, we found that desethylamiodarone (DEA) may have therapeutic potentiality in bladder cancer. In this study, we determined its effects on human cervical cancer cells (HeLa). Cell viability was evaluated by Muse Cell Count & Viability Assay; cell apoptosis was detected by Muse Annexin V & Dead Cell Assay. Cell cycle was flow cytometrically determined by Muse Cell Cycle Kit and the morphological changes of the cells were observed under a fluorescence microscope after Hoechst 33342 staining. The changes in the expression levels of apoptosis-related proteins in the HeLa cells were assessed by immunoblot. Our results showed that DEA significantly inhibited the proliferation and viability of HeLa cells and induced apoptosis in vitro in dose-dependent and also in cell cycle-dependent manner because DEA induced G0/G1 phase arrest in the HeLa cell line. We found that DEA treatment downregulated the expression of phospho-Akt and phospho-Bad. In addition, DEA could downregulate expression of Bcl-2, upregulate Bax, and induce cytochrome c release. Our results indicate that DEA might have significance as an anti-tumor agent against human cervical cancer.

Mutational analysis of pulmonary tumours with neuroendocrine features using targeted massive parallel sequencing: a comparison of a neglected tumour group

Background:

Lung cancer is the leading cause of cancer-related deaths worldwide. The typical and atypical carcinoid (TC and AC), the large-cell neuroendocrine carcinoma (LCNEC) and the small-cell lung cancers (SCLC) are subgroups of pulmonary tumours that show neuroendocrine differentiations. With the rising impact of molecular pathology in routine diagnostics the interest for reliable biomarkers, which can help to differentiate these subgroups and may enable a more personalised treatment of patients, grows.

Methods:

A collective of 70 formalin-fixed, paraffin-embedded (FFPE) pulmonary neuroendocrine tumours (17 TCs, 17 ACs, 19 LCNECs and 17 SCLCs) was used to identify biomarkers by high-throughput sequencing. Using the Illumina TruSeq Amplicon-Cancer Panel on the MiSeq instrument, the samples were screened for alterations in 221 mutation hot spots of 48 tumour-relevant genes.

Results:

After filtering >26 000 detected variants by applying strict algorithms, a total of 130 mutations were found in 29 genes and 49 patients. Mutations in JAK3, NRAS, RB1 and VHL1 were exclusively found in SCLCs, whereas the FGFR2 mutation was detected in LCNEC only. KIT, PTEN, HNF1A and SMO were altered in ACs. The SMAD4 mutation corresponded to the TC subtype. We prove that the frequency of mutations increased with the malignancy of tumour type. Interestingly, four out of five ATM-mutated patients showed an additional alteration in TP53, which was by far the most frequently altered gene (28 out of 130; 22%). We found correlations between tumour type and IASLC grade for ATM- (P=0.022; P=0.008) and TP53-mutated patients (P<0.001). Both mutated genes were also associated with lymph node invasion and distant metastasis (P⩽0.005). Furthermore, PIK3CA-mutated patients with high-grade tumours showed a reduced overall survival (P=0.040) and the mutation frequency of APC and ATM in high-grade neuroendocrine lung cancer patients was associated with progression-free survival (PFS) (P=0.020).

Conclusions:

The implementation of high-throughput sequencing for the analysis of the neuroendocrine lung tumours has revealed that, even if these tumours encompass several subtypes with varying clinical aggressiveness, they share a number of molecular features. An improved understanding of the biology of neuroendocrine tumours will offer the opportunity for novel approaches in clinical management, resulting in a better prognosis and prediction of therapeutic response.

Driver gene mutations of non-small-cell lung cancer are rare in primary carcinoids of the lung: NGS study by ion Torrent

Lung carcinoids are rare neuroendocrine tumors of the lung. Very little is known about the genetic background of these tumors. We applied Ion Torrent Ampliseq next-generation technology to study hotspot mutations of 22 lung cancer-related genes from typical and atypical lung carcinoid tumors. DNA isolated from 25 formalin-fixed, paraffin-embedded carcinoid tumors were amplified to prepare barcoded libraries covering 507 mutations included in 90 amplicons. The libraries were pooled, purified, enriched, and sequenced on ion personal genome machine. The sequences were aligned and checked for known and novel variations using Torrent Suite Software v.4.0.2. One out of 25 patients had mutations in the targeted regions sequenced. This patient had mutations in BRAF, SMAD4, PIK3CA, and KRAS. All these mutations were confirmed as somatic and are previously known mutations. In summary, mutations in genes commonly mutated in non-small-cell lung cancer are not common in lung carcinoids.

P2X7 mRNA expression in non-small cell lung cancer: MicroRNA regulation and prognostic value

The human P2X7 receptor is significant and exhibits several functions in neoplasia. At present, little is known with regard to its regulation. P2X7 expression may be regulated post-transcriptionally and putative microRNA (miRNA) binding sites are considered to be involved. The aim of this study was to determine whether miRNAs (miR-21, let-7 g and miR-205) regulate P2X7 mRNA stability. In addition, the impact of P2X7 expression in patients with non-small cell lung cancer (NSCLC) was investigated. P2X7 mRNA and mature Let-7 g, miR-21, and miR-205 expression levels were quantified in 96 NSCLC cases using quantitative reverse transcription polymerase chain reaction. In all samples, epidermal growth factor receptor and K-Ras mutational analysis was also performed. Samples with low P2X7 expression were found to exhibit a higher fold change in miR-21 expression when compared with samples exhibiting high P2X7 expression. Significantly higher miR-21 expression was observed in the tumors of NSCLC patients with a K-Ras mutation when compared with patients who had K-Ras wild-type tumors (P=0.003). Additionally, to evaluate the association between P2X7 expression and prognosis in NSCLC patients, survival analysis was performed using the Kaplan-Meier method. A significant difference in the progression-free survival and overall survival in the NSCLC patients with high P2X7 expression was identified, when compared with that of patients with low expression (P=0.03 and P=0.02, respetively). Therefore, we hypothesized that high levels of miR-21 expression in NSCLC patients with K-Ras mutations may be regulated by a complex circuit, including P2X7 downregulation and together these processes may promote tumor progression.

Let-7g and miR-21 expression in non-small cell lung cancer: correlation with clinicopathological and molecular features

MicroRNAs (miRNAs) play a key role in cancer pathogenesis and are involved in several human cancers, including non-small cell lung cancer (NSCLC). This study evaluated Let-7g and miR-21 expression by quantitative real-time PCR in 80 NSCLC patients and correlated the results with their main clinicopathological and molecular features. MiR-21 expression was significantly higher in NSCLC tissues compared to non-cancer lung tissues (p<0.0001), while no significant changes in Let-7g expression were observed between the tumor and normal lung tissues. Target prediction analysis led to the identification of 26 miR-21 and 24 Let-7g putative target genes that play important roles in cancer pathogenesis and progression. No significant association was observed between the analysed miRNAs and the main clinicopathological or molecular characteristics of the NSCLC patients, although both miRNAs were downregulated in squamous cell carcinomas compared to adenocarcinomas. Noteworthy, we observed a significant association between low Let-7g expression and metastatic lymph nodes at diagnosis (p=0.046), as well as between high miR-21 expression and K-Ras mutations (p=0.0003). Survival analysis did not show any significant correlation between prognosis and the analysed miRNAs, although the patients with a high Let-7g and miR-21 expression showed a significantly lower short-term progression-free survival (p=0.01 and p=0.0003, respectively) and overall survival (p=0.023 and p=0.0045, respectively). In conclusion, we showed that Let-7g and miR-21 expression was deregulated in NSCLC and we demonstrated a strong relationship between miR-21 overexpression and K-Ras mutations. Our data indicate that Let-7g and miR-21 profiling combined with the determination of K-Ras mutational status may be considered a useful biomarker for a more effective molecular characterization and clinical management of NSCLC patients.

PIK3CA mutations are frequently observed in BRCAX but not BRCA2-associated male breast cancer

INTRODUCTION

Although a substantial proportion of male breast cancers (MBCs) are hereditary, the molecular pathways that are activated are unknown. We therefore examined the frequency and clinicopathological associations of the PIK3CA/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) pathways and their regulatory genes in familial MBC.

METHODS

High resolution melting analysis and confirmatory sequencing was used to determine the presence of somatic mutations in PIK3CA (exon 9 and 20), AKT1 (exon 4), KRAS (exon 2) and BRAF (exon 15) genes in 57 familial MBCs. Further analysis of the PIK3CA/mTOR pathway was performed using immunohistochemistry for the pAKT1, pS6 and p4EBP1 biomarkers.

RESULTS

PIK3CA somatic mutations were identified in 10.5% (6 of 57) of cases; there were no AKT1, KRAS or BRAF somatic mutations. PIK3CA mutations were significantly more frequent in cancers from BRCAX patients (17.2%, 5/29) than BRCA2 (0%, 0/25) carriers (P = 0.030). Two BRCAX patients had an E547K mutation which has only been reported in one female breast cancer previously. PIK3CA mutation was significantly correlated with positive pS6 (83.3% vs. 32.0%, P = 0.024) and negative p4EBP1 (100% vs. 38.0%, P = 0.006) expression, but not pAKT expression. Expression of nuclear p4EBP1 correlated with BRCA2 mutation carrier status (68.0% vs. 38.7%, P = 0.035).

CONCLUSIONS

Somatic PIK3CA mutation is present in familial male breast cancer but absent in BRCA2 carriers. The presence of two of the extremely rare E547K PIK3CA mutations in our cohort may have specific relevance in MBCs. Further study of PIK3CA in MBCs, and in particular BRCAX patients, may contribute to further establishing the relevance of specific PIK3CA mutations in MBC aetiology and in the identification of particular patient groups most likely to benefit from therapeutic targeting with the novel PIK3CA inhibitors that are currently in development.