Other signalization targets

Treatment decisions for patients with lung cancer have historically been based upon tumor morphological analysis. Over the past decade, some molecular alterations have been identified as being necessary and sufficient to drive tumor carcinogenesis. These “driver” mutations occur in genes that encode signaling proteins critical for cellular proliferation and survival. Epidermal growth factor (EGF) receptor (EGFR) mutations are the best illustration of the therapeutic relevance of identifying such molecular clusters of lung cancer based on driver genetic alterations that predict the efficacy of specific tyrosine kinase inhibitors, a strategy referred to as “personalized medicine.” Besides EGFR and ALK, other genes harboring driver molecular alterations have been identified as part of integrated genomic studies of lung cancers. The objectives of this review are (1) to provide the reader with preclinical and clinical data on these new oncogenic mutations, focusing on druggable ones; (2) to discuss the dynamic nature of lung cancer molecular features in the context of acquired resistance to specific inhibitors; and (3) to highlight emerging data on other cancer hallmarks that may be of interest from a therapeutic perspective in the next future. From bench to bedside, personalized medicine represents a major revolution in the treatment of lung cancer.     

Targeted exome sequencing for the identification of common mutational signatures and potential driver mutations for brain metastases and prognosis

Brain metastases (BMs) are malignancies in the central nervous system with poor prognosis. Genetic landscapes of the primary tumor sites have been extensively profiled; however, mutations associated with BMs are poorly understood. In the present study, target exome sequencing of 560 cancer-associated genes in samples from 52 patients with brain metastasis from various primary sites was performed. Recurrent mutations for BMs from distinct origins were identified. There were both genetic homogeneity and heterogeneity between BMs and primary lung tumor tissues. The mutation rate of the major cancer driver gene, TP53, was consistently high in both the primary lung cancer sites and BMs, while some genetic alterations, associated with DNA damage response deficiency, were specifically enriched in BMs. The mutational signatures enriched in BMs could serve as actionable targets for treatment. The mutation in the primary site of the potential brain metastasis driver gene, nuclear mitotic apparatus protein 1 (NUMA1), affected the progression-free survival time of patients with lung cancer, and patients with the NUMA1 mutation in BMs had a good prognosis. This suggested that the occurrence and clinical outcome of brain metastases could be independent of each other.     

肺鳞癌的分子病理学研究进展

肺鳞癌是最具代表性的多发于吸烟人群的恶性肿瘤。目前研究多集中在肺腺癌和不吸烟患者,对鳞癌分子病理学改变的认知远远落后于腺癌。未来非小细胞肺癌的研究热点将集中在鉴定不同肺癌亚型的分子改变及研发相应靶点的靶向治疗药物。近来研究已发现多个具有潜在临床指导意义的抗肿瘤靶点并即将制成鳞癌基因图谱,有望为鳞癌的基因分型提供依据。本文将对肺鳞癌分子病理学的最新研究进展作一综述。     

Advances in Targeted Therapy Against Driver Mutations and Epigenetic Alterations in Non-Small Cell Lung Cancer

The incidence and mortality of lung cancer rank top three of all cancers worldwide. Accounting for 85% of the total number of lung cancer, non-small cell lung cancer (NSCLC) is an important factor endangering human health. Recently, targeted therapies against driver mutations and epigenetic alterations have made encouraging advances that benefit NSCLC patients. Druggable driver mutations, which mainly occur in EGFR, KRAS, MET, HER2, ALK, ROS1, RET and BRAF, have been identified in more than a quarter of NSCLC patients. A series of highly selective mutant targeting inhibitors, such as EGFR tyrosine kinase inhibitors and KRAS inhibitors, have been well studied and applied in clinical treatments, which greatly promote the overall survival of NSCLC patients. However, drug resistance has become a major challenge for targeted treatment, and a variety of methods to overcome drug resistance are constantly being developed, including inhibitors against new mutants, combination therapy with other pathway inhibitors, etc. In addition, epigenetics-based therapy is emerging. Epigenetic regulators such as histone deacetylases and non-coding RNA play a crucial role in the development of cancer and drug resistance by affecting multiple signaling pathways. Epigenetics-based therapeutic strategies combined with targeted drugs show great clinical potential. Many agents targeting epigenetic changes are being investigated in preclinical studies, with some already under clinical trials. This article focuses on driver mutations and epigenetic alterations in association with relevant epidemiological data. We introduce the current status of targeted inhibitors and known drug resistance, review advances in major targeted therapies with recent data from preclinical and clinical trials, and discuss the possibility of combination therapy against driver mutations and epigenetic alterations in overcoming drug resistance.     

Oncogenic driver mutations in non-small cell lung cancer: Past,present and future

Lung cancer, of which non-small lung cancer is the most common subtype, represents the leading cause of cancer related-death worldwide. It is now recognized that a significant proportion of these patients present alterations in certain genes that drive oncogenesis. In recent years, more of these so-called oncogenic drivers have been identified, and a better understanding of their biology has allowed the development new targeted agents. This review aims to provide an update about the current landscape of driver mutation in non-small-cell lung cancer. Alterations in Kirsten rat sarcoma, epidermal growth factor receptor, MET, anaplastic lymphoma kinase, c-ROS oncogene 1, v-raf murine sarcoma viral oncogene homolog B, neurotrophic receptor tyrosine kinase, human epidermal growth factor 2, neuregulin-1 and rearranged during transfection are discussed, as well as agents targeting these alterations. Current standards of treatment as well as promising future strategies are presented. Currently, more than fifteen targeted agents are food and Drug administration-approved for seven oncogenic drivers in non-small-cell lung cancer, highlighting the importance of actively searching for these mutations. Continuous and future efforts made in defining the biology of each of these alterations will help to elucidate their respective resistance mechanisms, and to define the best treatment strategy and therapeutic sequence.     

Highly frequent promoter methylation and <Emphasis Type="Italic">PIK3CA</Emphasis> amplification in non-small cell lung cancer (NSCLC)

Background  

Lung cancer is the leading cause of cancer-related death worldwide. Genetic and epigenetic alterations have been identified frequently in lung cancer, such as promoter methylation, gene mutations and genomic amplification. However, the interaction between genetic and epigenetic events and their significance in lung tumorigenesis remains poorly understood.     

Dissecting the genetic alterations involved in lung carcinogenesis

During the past two decades, considerable efforts have been devoted to the identification of the genes that drive lung cancer development. In spite of such intense research, only a few genes harboring mutations have been found, thus hindering the improvement in lung cancer treatment. The present review describes the catalog of known genetic alterations and the recent advances in global expression profiles in lung tumors and briefly discusses their use in clinical management.     

非小细胞肺腺癌驱动突变的研究进展

随着主要肿瘤基因测序项目的开展,来源于体细胞突变的驱动突变以其在癌症发生、发展、治疗中的重要作用受到广泛关注.新驱动突变的不断确认使人们对非小细胞肺癌（NSCLC）的认识从传统的病理分类到现今的基于分子水平改变的分子分型;NSCLC患者也已不再被看做是同一类型肿瘤的集合,而是多种具有不同分子生物学行为、对不同的靶向药物敏感的患者群体.文章着重就NSCLC中腺癌这一特殊病理类型的常见驱动突变及相关转化性医学研究进展作一概述.     

Loss of heterozygosity is related to p53 mutations and smoking in lung cancer

Carcinogenesis results from an accumulation of several genetic alterations. Mutations in the p53 gene are frequent and occur at an early stage of lung carcinogenesis. Loss of multiple chromosomal regions is another genetic alteration frequently found in lung tumours. We have examined the association between p53 mutations, loss of heterozygosity (LOH) at frequently deleted loci in lung cancer, and tobacco exposure in 165 tumours from non-small cell lung cancer (NSCLC) patients. A highly significant association between p53 mutations and deletions on 3p, 5q, 9p, 11p and 17p was found. There was also a significant correlation between deletions at these loci. 86% of the tumours with concordant deletion in the 4 most involved loci (3p21, 5q11-13, 9p21 and 17p13) had p53 mutations as compared to only 8% of the tumours without deletions at the corresponding loci (P< 0.0001). Data were also examined in relation to smoking status of the patients and histology of the tumours. The frequency of deletions was significantly higher among smokers as compared to non-smokers. This difference was significant for the 3p21.3 (hMLH1 locus), 3p14.2 (FHIT locus), 5q11-13 (hMSH3 locus) and 9p21 (D9S157 locus). Tumours with deletions at the hMLH1 locus had higher levels of hydrophobic DNA adducts. Deletions were more common in squamous cell carcinomas than in adenocarcinomas. Covariate analysis revealed that histological type and p53 mutations were significant and independent parameters for predicting LOH status at several loci. In the pathogenesis of NSCLC exposure to tobacco carcinogens in addition to clonal selection may be the driving force in these alterations.     

Targeted therapies: how personal should we go?

Despite the development of drugs inhibiting the oncogenic proteins that cancer cells are dependent on, attempts to match targeted therapies to the genetic makeup of individual tumors is proving more difficult than expected. Until now, the paradigm has been a binary correlation between a mutated cancer gene and response to a given therapy. However, recent evidence indicates that different genetic alterations, such as mutations in different codons of a cancer gene, might be related to distinct sensitivity to targeted therapies. An example is the divergent effect that individual EGFR, PIK3CA and KRAS mutations might have on response or resistance to tailored drugs. Furthermore, the idea that the presence of a specific mutation translates into sensitivity or resistance to a particular drug is likely too simplistic, since it does not capture the complexity of the signaling pathways in an individual cancer. Only the overall genetic milieu (alterations in upstream and/or parallel pathways) ultimately determines the response of individual tumors to therapy. We have critically analyzed data supporting the genetic, biological and biochemical differences of individual mutations within a single cancer gene. The role of cancer mutations as predictors of sensitivity and resistance to targeted therapies is discussed, together with the implications for the 'personalized' treatment of cancer patients.     

Proteogenomic systems analysis identifies targeted therapy resistance mechanisms in EGFR-mutated lung cancer

Cancer precision medicine largely relies on knowledge about genetic aberrations in tumors and next-generation-sequencing studies have shown a high mutational complexity in many cancers. Although a large number of the observed mutations is believed to be not causally linked with cancer, the functional effects of many rare mutations but also of combinations of driver mutations are often unknown. Here, we perform a systems analysis of a model of EGFR-mutated nonsmall cell lung cancer resistant to targeted therapy that integrates whole exome sequencing, global time-course discovery phosphoproteomics and computational modeling to identify functionally relevant molecular alterations. Our approach allows for a complexity reduction from over 2,000 genetic events potentially involved in mediating resistance to only 44 phosphoproteins and 35 topologically close genetic alterations. We perform single- and combination-drug testing against the predicted phosphoproteins and discovered that targeting of HSPB1, DBNL and AKT1 showed potent antiproliferative effects overcoming resistance against EGFR-inhibitory therapy. Our approach may therefore be used to complement mutational profiling to identify functionally relevant molecular aberrations and propose combination therapies across cancers.     

APC Gene Mutations in Human Prostate Cancer

Prostate cancer is the most common cancer in aged men. Althoughras and p53 gene mutations have been detected in some prostatecancers, the major genetic alterations involved in its carcinogenesisare not well understood. Mutation of the APC gene is responsiblefor colorectal tumors in which ras and p53 mutations are alsooften involved. Using PCR-SSCP analysis and sequencing, we examined31 human primary prostate cancers (three cases at stage A, 10at stage B, five at stage C and 13 at stage D) and four casesof lymph node metastasis from the stage D cases, for mutationsin the APC gene. A mutation was detected in only one of the35 samples (3%). This mutation, present in a primary stage Bcancer, had a T to C transition in exon 15 at the first positionof codon 956, resulting in substitution of histidine for tyrosine.This study clarified that APC gene mutations are not largelyinvolved in the development of clinical prostate cancer.     

Mutated circulating tumor DNA as a liquid biopsy in lung cancer detection and treatment

Over the past decade, substantial developments have been made in the detection of circulating tumor DNA (ctDNA)—cell‐free DNA (cfDNA) fragments released into the circulation from tumor cells and displaying the genetic alterations of those cells. As such, ctDNA detected in liquid biopsies serves as a powerful tool for cancer patient stratification, therapy guidance, detection of resistance, and relapse monitoring. In this Review, we describe lung cancer diagnosis and monitoring strategies using ctDNA detection technologies and compile recent evidence regarding lung cancer‐related mutation detection in liquid biopsy. We focus not only on epidermal growth factor receptor (EGFR) alterations, but also on significant co‐mutations that shed more light on novel ctDNA‐based liquid biopsy applications. Finally, we discuss future perspectives of early‐cancer detection and clonal hematopoiesis filtering strategies, with possible inclusion of microbiome‐driven liquid biopsy.     

Histological transformation after acquired resistance to epidermal growth factor tyrosine kinase inhibitors

Non-small-cell lung cancer patients with sensitive epidermal growth factor receptor mutations generally respond well to tyrosine kinase inhibitors (TKIs). However, acquired resistance will eventually develop place after 8–16 months. Several mechanisms contribute to the resistance including T790M mutation, c-Met amplification, epithelial mesenchymal transformation and PIK3CA mutation; however, histological transformation is a rare mechanism. The patterns and mechanisms underlying histological transformation need to be explored. We searched PubMed, EMBASE and search engines Google Scholar, Medical Matrix for literature related to histological transformation. Case reports, cases series, and clinical and basic medical research articles were reviewed. Sixty-one articles were included in this review. Cases of transformation to small-cell lung cancer, squamous cell carcinoma, large-cell neuroendocrine carcinoma and sarcoma after TKI resistance have all been reported. As the clinical course differed dramatically between cases, a new treatment scheme needs to be recruited. The mechanisms underlying histological transformation have not been fully elucidated and probably relate to cancer stem cells, driver genetic alterations under selective pressure or the heterogeneity of the tumor. When TKI resistance develops, we recommend that patients undergo a second biopsy to determine the reason, guide the next treatment and predict the prognosis.     

Mutational Damages in Malignant Lung Tumors

Background: Today, genomic changes are an important cause of the occurrence, growth and progression of cancer. Technological advances in cancer genomic analysis platforms have made it possible to identify genomic alterations that may influence response to lung cancer treatment. Methods: The study examined tumor growth-inhibiting oncogenes and genes responsible for cell growth and division to identify mutations characteristic of malignant lung tumors. The mutations were studied in 400 postoperative samples after amplifying p53 and HRAS fragments and p53, p21Waf1, MDM2 mRNA. p53 or p21Waf1 were expressed in 50% of squamous cell carcinomas and adenocarcinomas of the lung. Results: The study examined tumor growth-inhibiting oncogenes and genes responsible for cell growth and division to identify mutations characteristic of malignant lung tumors. The mutations were studied in 400 postoperative samples after amplifying p53 and HRAS fragments and p53, p21Waf1, MDM2 mRNA. p53 or p21Waf1 were expressed in 50% of squamous cell carcinomas and adenocarcinomas of the lung. HRAS mutations were present in most squamous cell carcinomas and adenocarcinomas of the lung. EcoR1- and Pst1- restriction enzymes destroyed the RT-PCR product of the p53 and p21Waf1 mRNA and increased the level of detected mutations in lung adenocarcinoma to 75% and 50 %, respectively. EGFR mutations were more frequent in lung adenocarcinoma than in lung squamous cell carcinoma. Mutations in EGFR exons 19 and 21 found in 65 of 263 lung tumor samples indicated the tumor sensitivity to EGFR tyrosine kinase inhibitors. EGFR deletions in exon 19 occurred mainly in adenocarcinoma, L858R mutations in EGFR exon 21 were quite common in lung adenocarcinoma. Conclusion: The mutations detected in most squamous cell carcinomas and adenocarcinomas of the lung could be used to diagnose and predict the disease severity and targeted therapy efficacy.     

Molecular footprints of human lung cancer progression

Lung cancer is the leading cause of cancer-related death in the world. To understand the molecular processes and pathways of, and contributing factors to lung cancer progression, genetic alterations in various progression stages of lung cancer cells have been studied, since these alterations can be regarded as molecular footprints representing the individual processes of multistage lung carcinogenesis. The results indicate that defects in both the p53 and RB/p16 pathways are essential for the malignant transformation of lung epithelial cells. Several other genes, such as K-ras, PTEN and MYO18B, are genetically altered less frequently than p53 and RB/p16 in lung cancer cells, suggesting that alterations in these genes are associated with further malignant progression or unique phenotypes in a subset of lung cancer cells. However, it is still unclear what genes control the metastatic potential of lung cancer cells. Further analyses of molecular footprints in lung cancer cells, in particular in the cells of metastatic sites, will give us valuable information to fully understand the process of lung cancer progression, and to find novel ways of controlling it. Molecular footprints at the sites of p53 mutations and p16 deletions further indicate that DNA repair activities for G:C to T:A transversion and non-homologous end-joining of DNA double-strand breaks play important roles in the accumulation of genetic alterations in lung cancer cells. Thus, identification of environmental as well as genetic factors inducing or suppressing the occurrence of such alterations would be a clue to find novel ways of lung cancer prevention.     

MSH6 germline mutations in early-onset colorectal cancer patients without family history of the disease

Germline MLH1 and MSH2 mutations are scarce in young colorectal cancer patients with negative family history of the disease. To evaluate the contribution of germline MSH6 mutations to early-onset colorectal cancer, we have analysed peripheral blood of 38 patients diagnosed with this disease before 45 years of age and who presented no family history of hereditary nonpolyposis colorectal cancer-related cancers. Blood samples from 108 healthy volunteers were analysed for those genetic alterations suspected to affect the function of MSH6. Of the seven (18.4%) MSH6 alterations found, we have identified three novel germline mutations, one 8 bp deletion leading to a truncated protein and two missense mutations resulting in the substitution of amino acids belonging to different polarity groups. High-frequency microsatellite instability was found in the patient with the MSH6 deletion, but not in the other 27 carcinomas analysed. No MLH1 promoter methylation was detected in tumour tissue. Our findings suggest that germline MSH6 mutations contribute to a subset of early-onset colorectal cancer. Further studies are warranted to understand the genetic and environmental factors responsible for the variable penetration of MSH6 germline mutations, as well as to identify other causes of early-onset colorectal cancer.     

Mutations of the human interferon alpha-2b (hIFNα-2b) gene in cancer patients receiving radiotherapy

This research aimed to find out the impact of ionizing radiations on the hIFNα-2b gene of radiotherapy treated cancer patients. The gene hIFNα-2b synthesizes a protein which is an important anticancerous and antiviral protein. The cancer patients (breast, lung, thyroid, oral and prostate) who were undergoing a radiotherapy treatment were selected. A molecular analysis was performed for DNA isolation and gene amplification through PCR, to identify gene mutations. Further, by bioinformatics tools we concluded that how mutations identified in gene sequences have led to the alterations in the hINFα-2b protein in radiotherapy receiving cancer patients. The 32% mutations in the hINFα-2b gene were identified and all were frameshift mutations. Radiotherapy can impact the immune system and cancer patients may modulate their immunity. Understaning the mechanisms of radiotherapy-elicited immune response may be helpful in the development of those therapeutic interventions that can enhance the efficacy of radiotherapy.     

WWOX gene may contribute to progression of non-small-cell lung cancer (NSCLC)

Lung cancer is the most common cause of cancer-related death worldwide and, like many other cancers, is affected by different genetic, epigenetic, and environmental factors. The WW domain-containing oxidoreductase (WWOX) gene is a tumor-suppressor gene located on chromosome 16q23.3–24.1, and it has been shown that it loses its function due to alterations in genetic and epigenetic mechanisms. The aim of this study is to investigate the relationship between lung cancer and WWOX gene. Tumor tissue samples, corresponding normal tissues, and blood samples obtained from 50 lung cancer patients were involved in the study. We analyzed methylation profile by methylation-specific PCR and mutations and polymorphisms by DNA sequencing. Methylation analysis showed that promoter hypermethylation was present in 38 of 50 (76%) patients. In addition, promoter region of WWOX gene of younger patients was more frequently methylated than older patients. Using DNA sequencing, we found four genetic alterations in WWOX gene. Two of them were germline mutations (Exon 4 and 7), and two of them were polymorphic (Exon 6 and 8). We found a new mutation in exon 7 (Arg-254→Cys) which has not been described previously. The changes in the short-chain dehydrogenase domain of the protein caused by the genetic alterations may affect the function of the gene. We conclude that hypermethylation of WWOX gene promoter region and mutations in the gene might be related to lung carcinogenesis.