Methylation Density Pattern of KEAP1 Gene in Lung Cancer Cell Lines Detected by Quantitative Methylation Specific PCR and Pyrosequencing.

BACKGROUND: The KEAP1/NRF2 pathway is the key regulator of antioxidants and cellular stress responses, and is implicated in neoplastic progression and resistance of tumors to treatment. KEAP1 silencing by promoter methylation is widely reported in solid tumors as part of the complex regulation of the KEAP1/NRF2 axis, but its prognostic role remains to be addressed in lung cancer. METHODS: We performed a detailed methylation density map of 13 CpGs located into the KEAP1 promoter region by analyzing a set of 25 cell lines from different histologies of lung cancer. The methylation status was assessed using quantitative methylation specific PCR (QMSP) and pyrosequencing, and the performance of the two assays was compared. RESULTS: Hypermethylation at the promoter region of the KEAP1 was detected in one third of cell lines and its effect on the modulation KEAP1 mRNA levels was also confirmed by in vitro 5-Azacytidine treatment on lung carcinoid, small lung cancer and adenocarcinoma cell lines. QMSP and pyrosequencing showed a high rate of concordant results, even if pyrosequencing revealed two different promoter CpGs sub-islands (P1a and P1b) with a different methylation density pattern. CONCLUSIONS: Our results confirm the effect of methylation on KEAP1 transcription control across multiple histologies of lung cancer and suggest pyrosequencing as the best approach to investigate the pattern of CpGs methylation in the promoter region of KEAP1. The validation of this approach on lung cancer patient cohorts is mandatory to clarify the prognostic value of the epigenetic deregulation of KEAP1 in lung tumors.

Effects of KEAP1 Silencing on the Regulation of NRF2 Activity in Neuroendocrine Lung Tumors.

BACKGROUND: The KEAP1/NRF2 pathway has been widely investigated in tumors since it was implicated in cancer cells survival and therapies resistance. In lung tumors the deregulation of this pathway is mainly related to point mutations of KEAP1 and NFE2L2 genes and KEAP1 promoter hypermethylation, but these two genes have been rarely investigated in low/intermediate grade neuroendocrine tumors of the lung. METHODS: The effects of KEAP1 silencing on NRF2 activity was investigated in H720 and H727 carcinoid cell lines and results were compared with those obtained by molecular profiling of KEAP1 and NFE2L2 in a collection of 47 lung carcinoids. The correlation between methylation and transcript levels was assessed by 5-aza-dC treatment. RESULTS: We demonstrated that in carcinoid cell lines, the KEAP1 silencing induces an upregulation of NRF2 and some of its targets and that there is a direct correlation between KEAP1 methylation and its mRNA levels. A KEAP1 hypermethylation and Loss of Heterozygosity at KEAP1 gene locus was also observed in nearly half of lung carcinoids. CONCLUSIONS: This is the first study that has described the effects of KEAP1 silencing on the regulation of NRF2 activity in lung carcinoids cells. The epigenetic deregulation of the KEAP1/NRF2 by a KEAP1 promoter hypermethylation system appears to be a frequent event in lung carcinoids.

Clinical impact of mixed pulmonary carcinoma and carcinoid: the driver from their mono-clonal origin.

The combination of neuroendocrine/non neuroendocrine lung tumors (CNNELT) mentioned in the last edition of the World Health Organization (WHO) of Thoracic Tumors refers to small cell carcinoma (SCLC) or large cell neuroendocrine carcinoma (LCNEC) mixed with any other non-small cell lung carcinoma (NSCLC). Typical Carcinoid (TC)/Atypical Carcinoid (AC) combined with NSCLC is not included among this category. However, case reports of TC/AC combined with NSCLC have been described. We previously reported 2 cases of lung adenocarcinoma (LUA) mixed with carcinoid sharing mutations in both components supporting the hypothesis of a clonal origin. We extended our analysis to other four cases of mixed NSCLC-carcinoid by performing targeted-DNA and RNA-based NGS analysis in both primary and their paired lymph nodes metastasis. In all cases, LUA and AC components shared at least 1 common mutation (KRAS driver mutation p.Gly12Val in cases 1 and 3, AKAP13-RET fusion in case 2, and missense KRAS driver mutation p.Gly12Ala in case 4, reinforcing the hypothesis of a clonal origin. Moreover, the same mutation was detected in the metastasis constituted only by AC (cases 2 and 4). Although it is a rare malignancy in the lung, mixed LUA and TC/AC could be included among the histotypes for which a deep molecular characterization of both components is needed to identify the presence of potential druggable genetic alterations.

Effects of KEAP1 Silencing on NRF2 and NOTCH Pathways in SCLC Cell Lines.

The KEAP1/NRF2 pathway is a master regulator of several redox-sensitive genes implicated in the resistance of tumor cells against therapeutic drugs. The dysfunction of the KEAP1/NRF2 system has been correlated with neoplastic patients' outcomes and responses to conventional therapies. In lung tumors, the growth and the progression of cancer cells may also involve the intersection between the molecular NRF2/KEAP1 axis and other pathways, including NOTCH, with implications for antioxidant protection, survival of cancer cells, and drug resistance to therapies. At present, the data concerning the mechanism of aberrant NRF2/NOTCH crosstalk as well as its genetic and epigenetic basis in SCLC are incomplete. To better clarify this point and elucidate the contribution of NRF2/NOTCH crosstalk deregulation in tumorigenesis of SCLC, we investigated genetic and epigenetic dysfunctions of the KEAP1 gene in a subset of SCLC cell lines. Moreover, we assessed its impact on SCLC cells' response to conventional chemotherapies (etoposide, cisplatin, and their combination) and NOTCH inhibitor treatments using DAPT, a γ-secretase inhibitor (GSI). We demonstrated that the KEAP1/NRF2 axis is epigenetically controlled in SCLC cell lines and that silencing of KEAP1 by siRNA induced the upregulation of NRF2 with a consequent increase in SCLC cells' chemoresistance under cisplatin and etoposide treatment. Moreover, KEAP1 modulation also interfered with NOTCH1, HES1, and DLL3 transcription. Our preliminary data provide new insights about the downstream effects of KEAP1 dysfunction on NRF2 and NOTCH deregulation in this type of tumor and corroborate the hypothesis of a cooperation of these two pathways in the tumorigenesis of SCLC.

Clinical and Molecular Traits of a Novel SPECC1L-ALK Fusion in a Patient with Advanced Non-Small Cell Lung Cancer.

Anaplastic lymphoma kinase (ALK) fusions account for 5-7% of non-small cell lung cancer (NSCLC) patients, the therapeutic approaches for which have significantly evolved in the last few years. However, the response to target therapies remains heterogeneous, partially due to the many different ALK fusion variants reported to date. Rare fusion variants have also been discovered, but their role in influencing responses to ALK inhibitors (ALKis) remains poorly elucidated. Laboratory investigation at both the tissue and protein levels, and a molecular profile by next-generation sequencing (NGS) were performed on a lung biopsy sample from one patient with poorly differentiated adenocarcinoma. An in silico prediction model using ColabFold software v1.5.5 was used to model and predict the entire structure of the chimeric aberrant ALK protein. Here, we report a case of a former smoker, a 60-year-old man, diagnosed with NSCLC and undergoing ALK translocation. He received first-, second- and third-generation ALK protein inhibitors (ALKis), showing a clinical benefit for about 4 years. IHC analysis and the molecular examination of the tissue biopsy indicated a positive staining for ALK and a novel ALK gene fusion variant, involving the sperm antigen with calponin homology and coiled-coil domain 1-like (SPECC1L) gene with an unreported breakpoint in exon 7. The novel SPECCL1::ALK fusion was identified using Anchored Multiplex PCR (AMP)-NGS technology and was predicted to retain the Pkinase_Tyr domain at the carboxy-terminal region of the resulting chimeric protein. To the best of our knowledge, this is the first case of an ALK-positive NSCLC patient carrying the SPECC1L exon 7 fusion breakpoint and one of the few reports about clinical outcomes related to SPECC1L::ALK fusion. The in silico hypothesized biological role of this newly identified fusion variant corroborates the observed clinical response to multiple ALKis. The molecular findings also reinforce the utility of AMP-based NGS technology as a valuable tool for the identification of rare chromosomal events that may be related to the variability of patient outcomes to different ALKis treatments.

Design and experimental validation of OPERA_MET-A panel for deep methylation analysis by next generation sequencing.

DNA methylation is the most recognized epigenetic mark that leads to a massive distortion in cancer cells. It has been observed that a large number of DNA aberrant methylation events occur simultaneously in a group of genes, thus providing a growth advantage to the cell in promoting cell differentiation and neoplastic transformation. Due to this reason, methylation profiles have been suggested as promising cancer biomarkers. Here, we designed and performed a first step of validation of a novel targeted next generation sequencing (NGS) panel for methylation analysis, which can simultaneously evaluate the methylation levels at CpG sites of multiple cancer-related genes. The OPERA_MET-A methylation panel was designed using the Ion AmpliSeq™ technology to amplify 155 regions with 125-175 bp mean length and covers a total of 1107 CpGs of 18 cancer-related genes. The performance of the panel was assessed by running commercially available fully methylated and unmethylated control human genomic DNA (gDNA) samples and a variable mixture of them. The libraries were run on Ion Torrent platform and the sequencing output was analyzed using the "methylation_analysis" plugin. DNA methylation calls on both Watson (W) and Crick (C) strands and methylated:unmethylated ratio for each CpG site were obtained. Cell lines, fresh frozen and formalin-fixed paraffin-embedded (FFPE) lung cancer tissues were tested. The OPERA_MET-A panel allows to run a minimum of 6 samples/530 chip to reach an observed mean target depth ≥2,500X (W and C strands) and an average number of mapped reads >750,000/sample. The conversion efficiency, determined by spiking-in unmethylated Lambda DNA into each sample before the bisulfite conversion process, was >97% for all samples. The observed percentage of global methylation for all CpGs was >95% and <5% for fully methylated and unmethylated gDNA samples, respectively, and the observed results for the variable mixtures were in agreement with what was expected. Methylation-specific NGS analysis represents a feasible method for a fast and multiplexed screening of cancer patients by a high-throughput approach. Moreover, it offers the opportunity to construct a more robust algorithm for disease prediction in cancer patients having a low quantity of biological material available.

Neuroendocrine-Related Circulating Transcripts in Small-Cell Lung Cancers: Detection Methods and Future Perspectives.

No well-established prognostic or predictive molecular markers of small-cell lung cancer (SCLC) are currently available; therefore, all patients receive standard treatment. Adequate quantities and quality of tissue samples are frequently unavailable to perform a molecular analysis of SCLC, which appears more heterogeneous and dynamic than expected. The implementation of techniques to study circulating tumor cells could offer a suitable alternative to expand the knowledge of the molecular basis of a tumor. In this context, the advantage of SCLC circulating cells to express some specific markers to be explored in blood as circulating transcripts could offer a great opportunity in distinguishing and managing different SCLC phenotypes. Here, we present a summary of published data and new findings about the detection methods and potential application of a group of neuroendocrine related transcripts in the peripheral blood of SCLC patients. In the era of new treatments, easy and rapid detection of informative biomarkers in blood warrants further investigation, since it represents an important option to obtain essential information for disease monitoring and/or better treatment choices.

Mixed Pulmonary Adenocarcinoma and Atypical Carcinoid: A Report of Two Cases of a Non-codified Entity With Biological Profile.

Pulmonary carcinoids combined with a non-neuroendocrine component have rarely been described, and this histological subtype is not included as a specific entity in the current World Health Organization classification of pulmonary neoplasms. Here, we described the molecular and histological features of two rare cases of mixed lung neoplasms, composed of atypical carcinoid and adenocarcinoma. The targeted next-generation sequencing analysis covering single nucleotide variations, copy number variations, and transcript fusions in a total of 161 cancer genes of the two different tumor components shows a similar molecular profile of shared and private gene mutations. These findings suggest their monoclonal origin from a transformed stem/progenitor tumor cell, which acquires a divergent differentiation during its development and progression and accumulates novel, specific mutations.

Potential Prognostic Role of SPARC Methylation in Non-Small-Cell Lung Cancer.

The silencing of SPARC (secreted protein acid and rich in cysteine) gene through methylation of its promoter region represents a common event in many solid tumors and it is frequently associated with tumor progression and an aggressive clinical outcome. Anyhow, the data concerning the epigenetic mechanism of SPARC deregulation and its prognostic value in lung cancer are still incomplete. We explored the aberrant methylation of SPARC and its effects in 4 non-small cell lung cancer (NSCLC) cell lines and 59 NSCLC tissues and correlated the methylation levels with clinical-pathological features and disease outcome of patients. In 3 out of 4 tumor cell lines high SPARC methylation levels were observed. An inverse correlation between the epigenetic silencing and SPARC expression was confirmed by 5-Aza-2'-deoxycytidine ((5-Aza-CdR) treatment that also significantly induced a reduction in cell viability, proliferation and tumor cell migration. In tissues, the DNA methylation levels of the SPARC gene were significantly lower in paired non-neoplastic lungs (NLs) and normal lungs distant from tumor (NLDTs) than in NSCLCs (p = 0.002 and p = 0.0034 respectively). A promoter hypermethylation was detected in 68% of squamous cell carcinoma (SqCCs, 17/25) and 56% of adenocarcinoma (ADCs, 19/34), with SqCC showing the highest levels of methylation. Higher SPARC methylation levels were significantly associated with higher mortality risk both in all NSCLCs early stage patients (Hazard Ratio, HR = 1.97; 95% Confidence Interval, CI: 1.32-2.93; p = 0.001) and in those with SqCC (HR = 2.96; 95% CI: 1.43-6.12; p = 0.003). Promoter methylation of SPARC gene should represent an interesting prognostic biomarker in NSCLC, with potential application in the squamous early-stage context. Further research in this setting on larger independent cohorts of lung patients with different histologies and stages of disease are warranted.

Automated Workflow for Somatic and Germline Next Generation Sequencing Analysis in Routine Clinical Cancer Diagnostics.

Thanks to personalized medicine trends and collaborations between industry, clinical research groups and regulatory agencies, next generation sequencing (NGS) is turning into a common practice faster than one could have originally expected. When considering clinical applications of NGS in oncology, a rapid workflow for DNA extraction from formalin-fixed paraffin-embedded (FFPE) tissue samples, as well as producing high quality library preparation, can be real challenges. Here we consider these targets and how applying effective automation technology to NGS workflows may help improve yield, timing and quality-control. We firstly evaluated DNA recovery from archived FFPE blocks from three different manual extraction methods and two automated extraction workstations. The workflow was then implemented to somatic (lung/colon panel) and germline (BRCA1/2) library preparation for NGS analysis exploiting two automated workstations. All commercial kits gave good results in terms of DNA yield and quality. On the other hand, the automated workstation workflow has been proven to be a valid automatic extraction system to obtain high quality DNA suitable for NGS analysis (lung/colon Ampli-seq panel). Moreover, it can be efficiently integrated with an open liquid handling platform to provide high-quality libraries from germline DNA with more reproducibility and high coverage for targeted sequences in less time (BRCA1/2). The introduction of automation in routine workflow leads to an improvement of NGS standardization and increased scale up of sample preparations, reducing labor and timing, with optimization of reagents and management.

Frequent NRG1 fusions in Caucasian pulmonary mucinous adenocarcinoma predicted by Phospho-ErbB3 expression.

NRG1 fusions were recently reported as a new molecular feature of Invasive Mucinous Adenocarcinoma (IMA) of the lung. The NRG1 chimeric ligand acts as a strong inductor of phosphorylation and tyrosine kinase activity of the ErbB2/ErbB3 heterodimer, thus enhancing the PI3K-AKT/MAPK pathways. The NRG1 fusions were widely investigated in Asian IMA cohorts, whereas just anecdotal information are available about the occurrence of NRG1 fusions in IMA Caucasian population. Here we firstly explored a large Caucasian cohort of 51 IMAs and 34 non-IMA cases for the occurrence of NRG1 rearrangements by fluorescent in situ hybridization (FISH) and RNA target sequencing. FISH results were correlated to the immunohistochemical expression of phosphorylated-ErbB3 (pErbB3) receptor and the mutational status of KRAS, EGFR and ALK genes. The NRG1 rearrangements were detected in 31% IMAs and 3% non-IMAs and the CD74-NRG1 fusion transcript variant was characterized in 4 NRG1-positive IMAs. Moreover, pErbB3 expression was found to be strictly associated to the mucinous pattern (p = 0.012, Chi-square test) and all IMA cases showing aberrant expression of pErbB3 demonstrated NRG1 rearrangements. No significant correlation between NRG1 rearrangements and EGFR, KRAS or ALK mutations respectively, was observed. We report for the first time that NRG1 fusions are driver alterations clearly associated with mucinous lung adenocarcinoma subtype of Caucasian patients and not exclusive of Asiatic population. pErbB3 immunostaining may represent a strong predictor of NRG1 fusions, pointing out the detection of pErbB3 by IHC as a rapid and effective pre-screening method to select the NRG1-positive patients.