Detection of K-ras gene mutations in non-neoplastic lung tissue and lung cancers

Game of clones: Battles in the field of carcinogenesis

Recent advances in bulk sequencing approaches as well as genomic decoding at the single-cell level have revealed surprisingly high somatic mutational burdens in normal tissues, as well as increased our understanding of the landscape of "field cancerization", that is, molecular and immune alterations in mutagen-exposed normal-appearing tissues that recapitulated those present in tumors. Charting the somatic mutational landscapes in normal tissues can have strong implications on our understanding of how tumors arise from mutagenized epithelium. Making sense of those mutations to understand the progression along the pathologic continuum of normal epithelia, preneoplasias, up to malignant tissues will help pave way for identification of ideal targets that can guide new strategies for preventing or eliminating cancers at their earliest stages of development. In this review, we will provide a brief history of field cancerization and its implications on understanding early stages of cancer pathogenesis and deviation from the pathologically "normal" state. The review will provide an overview of how mutations accumulating in normal tissues can lead to a patchwork of mutated cell clones that compete while maintaining an overall state of functional homeostasis. The review also explores the role of clonal competition in directing the fate of normal tissues and summarizes multiple mechanisms elicited in this phenomenon and which have been linked to cancer development. Finally, we highlight the importance of understanding mutations in normal tissues, as well as clonal competition dynamics (in both the epithelium and the microenvironment) and their significance in exploring new approaches to combatting cancer.

Comparison of tumor and two types of paratumoral tissues highlighted epigenetic regulation of transcription during field cancerization in non-small cell lung cancer

Background

Field cancerization is the process in which a population of normal or pre-malignant cells is affected by oncogenic alterations leading to progressive molecular changes that drive malignant transformation. Aberrant DNA methylation has been implicated in early cancer development in non-small cell lung cancer (NSCLC); however, studies on its role in field cancerization (FC) are limited. This study aims to identify FC-specific methylation patterns that could distinguish between pre-malignant lesions and tumor tissues in NSCLC.

Methods

We enrolled 52 patients with resectable NSCLC and collected resected tumor (TUM), tumor-adjacent (ADJ) and tumor-distant normal (DIS) tissue samples, among whom 36 qualified for subsequent analyses. Methylation levels were profiled by bisulfite sequencing using a custom lung-cancer methylation panel.

Results

ADJ and DIS samples demonstrated similar methylation profiles, which were distinct from distinct from that of TUM. Comparison of TUM and DIS profiles led to identification of 1740 tumor-specific differential methylated regions (DMRs), including 1675 hypermethylated and 65 hypomethylated (adjusted P < 0.05). Six of the top 10 tumor-specific hypermethylated regions were associated with cancer development. We then compared the TUM, ADJ, and DIS to further identify the progressively aggravating aberrant methylations during cancer initiation and early development. A total of 332 DMRs were identified, including a predominant proportion of 312 regions showing stepwise increase in methylation levels as the sample drew nearer to the tumor (i.e. DIS < ADJ < TUM) and 20 regions showing a stepwise decrease pattern. Gene set enrichment analysis (GSEA) for KEGG and GO terms consistently suggested enrichment of DMRs located in transcription factor genes, suggesting a central role of epigenetic regulation of transcription factors in FC and tumorigenesis.

Conclusion

We revealed distinct methylation patterns between pre-malignant lesions and malignant tumors, suggesting the essential role of DNA methylation as an early step in pre-malignant field defects. Moreover, our study also identified differentially methylated genes, especially transcription factors, that could potentially be used as markers for lung cancer screening and for mechanistic studies of FC and early cancer development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01192-1.

Calling Attention to the Role of Race-Driven Societal Determinants of Health on Aggressive Tumor Biology: A Focus on Black Americans

Blacks have the highest incidence and mortality from most cancers. The reasons for these disparities remain unclear. Blacks are exposed to adverse social determinants because of historic and contemporary racist polices; however, how these determinants affect the disparities that Blacks experience is understudied. As a result of discriminatory community policies, like redlining, Blacks have higher exposure to air pollution and neighborhood deprivation. Studies investigating how these factors affect tumor biology are emerging. We highlight the literature that connects racism-related community exposure to the tumor biology in breast, lung, prostate, and colorectal cancer. Further investigations that clarify the link between adverse social determinants that result from systemic racism and aggressive tumor biology are required if health equity is to be achieved. Without recognition that racism is a public health risk with carcinogenic impact, health care delivery and cancer care will never achieve excellence. In response, health systems ought to establish corrective actions to improve Black population health and bring medical justice to marginalized racialized groups.

Bronchiolar adenomas (BA) - A detailed radio-pathologic analysis of six cases and review of literature

Bronchiolar adenomas (BAs)/ciliated muco-nodular papillary tumors (CMPTs), are small, peripheral lung nodules arising predominantly in the elderly that follow a benign course. They can be mistaken for adenocarcinomas on frozen section. Immunohistochemistry (IHC) for basal cell markers highlights the continuous layer of basal cells underlying the tumor cells in BAs. BAs are further subdivided into proximal-type and distal type. Six BAs were retrieved from the pathology archives. The cases were classified based on morphology into proximal and distal BAs. The clinical and radiological features were reviewed. Immunohistochemistry and special stains were performed. The most common radiological picture of BA/CMPT was of a solid nodule with SUV_max < 3 as seen in 60% cases. 40% cases showed cavitation on CT. On histological examination, four cases were morphologically classified as proximal BAs and two as distal BAs. In proximal BAs, TTF1 was focally positive only in the basal cells in three of four. The mucin stained acidic. In distal BAs, TTF1 was diffusely positive in both basal and luminal cells. There was scant intracellular neutral mucin. Both the distal BAs had concomitant neuroendocrine tumors in the same lobe. Though the number of cases evaluated in this study is too low to be statistically significant, this study provides additional evidence to the concept of BA classification based on site specific histology and supplementary immunohistochemistry and reiterates the radiological features that may help distinguish it from malignant lesions.

Adenocarcinoma spectrum lesions of the lung: Detection, pathology and treatment strategies

Adenocarcinoma has become the most prevalent lung cancer sub-type and its frequency is increasing. The earliest stages in the development of lung adenocarcinomas are visible using modern computed tomography (CT) as ground glass nodules. These pre-invasive nodules can progress over time to become invasive lung adenocarcinomas. Lesions in this developmental pathway are termed 'adenocarcinoma spectrum' lesions. With the introduction of lung cancer screening programs there has been an increase in the detection of these lesions raising questions about natural history, surveillance and treatment. Here we review how the radiological appearance of an adenocarcinoma spectrum lesion relates to its underlying pathology and explore the natural history and factors driving lesion progression. We examine the molecular changes that occur at each stage of adenocarcinoma spectrum lesion development, including the effects of the driver mutations, EGFR and KRAS, that are key to invasive adenocarcinoma pathology. A better understanding of the development of pre-invasive disease will create treatment targets. Our understanding of how tumours interact with the immune system has led to the development of new therapeutic strategies. We review the role of the immune system in the development of adenocarcinoma spectrum lesions. With a clear preinvasive phase there is an opportunity to treat early adenocarcinoma spectrum lesions before an invasive lung cancer develops. We review current management including surveillance, surgical resection and oncological therapy as well as exploring potential future treatment avenues.

Field Cancerization in NSCLC: A New Perspective on MicroRNAs in Macrophage Polarization

Lung cancer is currently the first cause of cancer-related death. The major lung cancer subtype is non-small cell lung cancers (NSCLC), which accounts for approximatively 85% of cases. The major carcinogenic associated with lung cancer is tobacco smoke, which produces long-lasting and progressive damage to the respiratory tract. The progressive and diffuse alterations that occur in the respiratory tract of patients with cancer and premalignant lesions have been described as field cancerization. At the level of tumor cells, adjacent tumor microenvironment (TME) and cancerized field are taking place dynamic interactions through direct cell-to-cell communication or through extracellular vesicles. These molecular messages exchanged between tumor and nontumor cells are represented by proteins, noncoding RNAs (ncRNAs) and microRNAs (miRNAs). In this paper, we analyze the miRNA roles in the macrophage polarization at the level of TME and cancerized field in NSCLC. Identifying molecular players that can influence the phenotypic states at the level of malignant cells, tumor microenvironment and cancerized field can provide us new insights into tumor regulatory mechanisms that can be further modulated to restore the immunogenic capacity of the TME. This approach could revert alterations in the cancerized field and could enhance currently available therapy approaches.

Comparison of Mutated KRAS and Methylated HOXA9 Tumor-Specific DNA in Advanced Lung Adenocarcinoma

Circulating tumor DNA (ctDNA) has been suggested as a biomarker in non-small cell lung cancer. The optimal target for measuring ctDNA has not yet been established. This study aimed to investigate methylated Homeobox A9 (meth-HOXA9) as an approach to detect ctDNA in advanced lung adenocarcinoma and compare it with mutated Kirsten rat sarcoma viral oncogene homolog (mut-KRAS) in order to determine the mutual agreement. DNA was purified from formalin-fixed, paraffin-embedded non-malignant lung tissue and lung adenocarcinoma tissue, and plasma from healthy donors and lung adenocarcinoma patients, respectively. KRAS mutations in tumor tissue were identified by next-generation sequencing and quantified in tumor and plasma by droplet digital polymerase chain reaction (ddPCR). The meth-HOXA9 analysis was based on bisulfite-converted DNA from tumor and plasma and quantified by ddPCR. Samples consisted of 20 archival non-malignant lung tissues, 48 advanced lung adenocarcinomas with matched plasma samples, and 100 plasma samples from healthy donors. A KRAS mutation was found in the tumor in 34/48 (70.8%) adenocarcinoma patients. All tumors were positive for meth-HOXA9, while none of the non-malignant lung tissues were. Meth-HOXA9 was detected in 36/48 (75%) of plasma samples, and the median level was 0.7% (range of 0-46.6%, n = 48). Mut-KRAS was detected in 29/34 (85.3%) of the plasma samples, and the median level was 1.2% (range of 0-46.1%, n = 34). There was a good correlation between meth-HOXA9 and mut-KRAS in plasma (Spearman's rho 0.83, p < 0.001). Meth-HOXA9 is present in tissue from incurable lung adenocarcinoma but not in non-malignant lung tissue. It may be used as an approach for detecting ctDNA. The results demonstrated a high agreement between meth-HOXA9 and mut-KRAS in patients with advanced lung adenocarcinoma.

Tissue ACE phenotyping in lung cancer

Background

Pulmonary vascular endothelium is the main metabolic site for Angiotensin I-Converting Enzyme (ACE)-mediated degradation of several biologically-active peptides (angiotensin I, bradykinin, hemo-regulatory peptide Ac-SDKP). Primary lung cancer growth and lung cancer metastases decrease lung vascularity reflected by dramatic decreases in both lung and serum ACE activity. We performed precise ACE phenotyping in tissues from subjects with lung cancer.

Methodology

ACE phenotyping included: 1) ACE immunohistochemistry with specific and well-characterized monoclonal antibodies (mAbs) to ACE; 2) ACE activity measurement with two ACE substrates (HHL, ZPHL); 3) calculation of ACE substrates hydrolysis ratio (ZPHL/HHL ratio); 4) the pattern of mAbs binding to 17 different ACE epitopes to detect changes in ACE conformation induced by tumor growth (conformational ACE fingerprint).

Results

ACE immunostaining was dramatically decreased in lung cancer tissues confirmed by a 3-fold decrease in ACE activity. The conformational fingerprint of ACE from tumor lung tissues differed from normal lung (6/17 mAbs) and reflected primarily higher ACE sialylation. The increase in ZPHL/HHL ratio in lung cancer tissues was consistent with greater conformational changes of ACE. Limited analysis of the conformational ACE fingerprint in normal lung tissue and lung cancer tissue form the same patient suggested a remote effect of tumor tissue on ACE conformation and/or on “field cancerization” in a morphologically-normal lung tissues.

Conclusions/Significance

Local conformation of ACE is significantly altered in tumor lung tissues and may be detected by conformational fingerprinting of human ACE.

Tobacco chemical-induced mouse lung adenocarcinoma cell lines pin the prolactin orthologue proliferin as a lung tumour promoter

Lung adenocarcinoma (LADC) is the leading cause of cancer death worldwide. Nevertheless, syngeneic mouse models of the disease are sparse, and cell lines suitable for transplantable and immunocompetent mouse models of LADC remain unmet needs. We established multiple mouse LADC cell lines by repeatedly exposing two mouse strains (FVB, Balb/c) to the tobacco carcinogens urethane or diethylnitrosamine and by culturing out the resulting lung tumours for prolonged periods of time. Characterization of the resulting cell lines (n = 7) showed that they were immortal and phenotypically stable in vitro, and oncogenic, metastatic and lethal in vivo. The primary tumours that gave rise to the cell lines, as well as secondary tumours generated by transplantation of the cell lines, displayed typical LADC features, such as glandular architecture and mucin and thyroid transcription factor 1 expression. Moreover, these cells exhibited marked molecular similarity with human smokers' LADC, including carcinogen-specific Kras point mutations (KrasQ61R in urethane- and KrasQ61H in diethylnitrosamine-triggered cell lines) and Trp53 deletions and displayed stemness features. Interestingly, all cell lines overexpressed proliferin, a murine prolactin orthologue, which functioned as a lung tumour promoter. Furthermore, prolactin was overexpressed and portended poor prognosis in human LADC. In conclusion, we report the first LADC cell lines derived from mice exposed to tobacco carcinogens. These cells closely resemble human LADC and provide a valuable tool for the functional investigation of the pathobiology of the disease.

Driver Mutations in Normal Airway Epithelium Elucidate Spatiotemporal Resolution of Lung Cancer

Rationale: Uninvolved normal-appearing airway epithelium has been shown to exhibit specific mutations characteristic of nearby non-small cell lung cancers (NSCLCs). Yet, its somatic mutational landscape in patients with early-stage NSCLC is unknown.Objectives: To comprehensively survey the somatic mutational architecture of the normal airway epithelium in patients with early-stage NSCLC.Methods: Multiregion normal airways, comprising tumor-adjacent small airways, tumor-distant large airways, nasal epithelium and uninvolved normal lung (collectively airway field), matched NSCLCs, and blood cells (n = 498) from 48 patients were interrogated for somatic single-nucleotide variants by deep-targeted DNA sequencing and for chromosomal allelic imbalance events by genome-wide genotype array profiling. Spatiotemporal relationships between the airway field and NSCLCs were assessed by phylogenetic analysis.Measurements and Main Results: Genomic airway field carcinogenesis was observed in 25 cases (52%). The airway field epithelium exhibited a total of 269 somatic mutations in most patients (n = 36) including key drivers that were shared with the NSCLCs. Allele frequencies of these acquired variants were overall higher in NSCLCs. Integrative analysis of single-nucleotide variants and allelic imbalance events revealed driver genes with shared "two-hit" alterations in the airway field (e.g., TP53, KRAS, KEAP1, STK11, and CDKN2A) and those with single hits progressing to two in the NSCLCs (e.g., PIK3CA and NOTCH1).Conclusions: Tumor-adjacent and tumor-distant normal-appearing airway epithelia exhibit somatic driver alterations that undergo selection-driven clonal expansion in NSCLC. These events offer spatiotemporal insights into the development of NSCLC and, thus, potential targets for early treatment.

Regulation of RhoB Gene Expression during Tumorigenesis and Aging Process and Its Potential Applications in These Processes

RhoB, a member of the Ras homolog gene family and GTPase, regulates intracellular signaling pathways by interfacing with epidermal growth factor receptor (EGFR), Ras, and phosphatidylinositol 3-kinase (PI3K)/Akt to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. Functionally, RhoB, part of the Rho GTPase family, regulates intracellular signaling pathways by interfacing with EGFR, RAS, and PI3K/Akt/mammalian target of rapamycin (mTOR), and MYC pathways to modulate responses in cellular structure and function. Notably, the EGFR, Ras, and PI3K/Akt pathways can lead to downregulation of RhoB, while simultaneously being associated with an increased propensity for tumorigenesis. RHOB expression has a complex regulatory backdrop consisting of multiple histone deacetyltransferase (HDACs 1 and 6) and microRNA (miR-19a, -21, and -223)-mediated mechanisms of modifying expression. The interwoven nature of RhoB’s regulatory impact and cellular roles in regulating intracellular vesicle trafficking, cell motion, and the cell cycle lays the foundation for analyzing the link between loss of RhoB and tumorigenesis within the context of age-related decline in RhoB. RhoB appears to play a tissue-specific role in tumorigenesis, as such, uncovering and appreciating the potential for restoration of RHOB expression as a mechanism for cancer prevention or therapeutics serves as a practical application. An in-depth assessment of RhoB will serve as a springboard for investigating and characterizing this key component of numerous intracellular messaging and regulatory pathways that may hold the connection between aging and tumorigenesis.

Targeted Sequencing Analysis of Pulmonary Adenocarcinoma with Multiple Synchronous Ground-Glass/Lepidic Nodules

INTRODUCTION

Lung adenocarcinoma (ADC) with synchronous ground-glass/lepidic (GG/L) nodules is considered a distinct disease entity in multiple synchronous lung cancers. Few studies have performed next-generation sequencing analysis of these synchronous sequential lesions, and genetic alterations of GG/L nodules must be further investigated.

METHODS

We performed targeted sequencing in ADC with synchronous atypical adenomatous hyperplasia (AAH), ADC in situ, or minimally invasive ADC from 16 patients. Next-generation sequencing was performed by using a customized panel including 154 cancer-associated genes.

RESULTS

Multiple synchronous lesions in the same patient showed different mutation profiles, and some shared identically mutated genes. In five patients harboring EGFR-mutant ADC, their synchronous GG/L nodules had EGFR mutation; however, none was observed in EGFR wild-type ADC. The average numbers of exonic mutations were 4.2, 5.4, 4.0, and 5.4 in AAH, ADC in situ, minimally invasive ADC, and ADC, respectively. In each lesion type, various mutations, including LDL receptor related protein 1B gene (LRP1B), KRAS, EGFR, and BRAF were observed in AAH, and EGFR mutations were the most frequently observed in ADC. In all, 80% of mutations with a variant allele frequency of 20% or higher, which contained driver gene mutations, were identified in ADC. Intratumoral heterogeneity of the genetic profile was found between the lepidic and invasive areas of ADC, but the driver gene mutations were similar.

CONCLUSIONS

This study suggests that ADC and synchronous GG/L nodules are genetically independent tumors. Intratumoral genetic heterogeneity of ADC was present, but driver gene mutations were homogeneously distributed. Driver gene mutations with a high variant allele frequency were identified in the invasive tumor. These findings support the relevance of molecular characterization of lung ADC and synchronous GG/L nodules.

Targeting the RAS-dependent chemoresistance: The Warburg connection

RAS protein family members (KRAS4A, KRAS4B, HRAS and NRAS) function as GDP-GTP-regulated on-off switches, which regulate cytoplasmic-nuclear signaling networks ruling diverse normal cellular processes. Constitutive activating mutations in RAS genes are found in up to 30% of human cancers, and remarkably, the oncogenic Ras mutations and mutations in other components of Ras/MAPK signaling pathways seem to be mutually exclusive in most tumors, pointing out that deregulation of Ras-dependent signaling is an essential requirement for tumorigenesis. Up to 30% of solid tumors are known to have a mutated (abnormal) KRAS gene. Unfortunately, patients harboring mutated KRAS CRC are unlikely to benefit from anti-EGFR therapy. Moreover, it remains unclear that patients with KRAS wild-type CRC will definitely respond to such therapies. Although some clinically designed-strategies to modulate KRAS aberrant activation have been designed, all attempts to target KRAS have failed in the clinical assays and K-RAS has been assumed to be invulnerable to chemotherapeutic attack. Recently, different encouraging publications reported that ascorbate may have a selective antitumoral effect on KRAS mutant cancer cells. In this review we aim to describe the prevalence and importance of KRAS mutation in cancer and associated problems for the clinical handling of patients harboring these tumors. We highlight the role of mutated KRAS in boosting and keeping the tumor associated aberrant cell metabolism stating that further in-depth studies on the molecular mechanism of ascorbate to bypass mutated KRAS-related metabolic alterations may constitute a new pathway to design novel molecules in order handle tumor resistance to anti EGFR-therapies.

Standardizing biomarker testing for Canadian patients with advanced lung cancer

BACKGROUND

The development and approval of both targeted and immune therapies for patients with advanced non-small cell lung cancer (nsclc) has significantly improved patient survival rates and quality of life. Biomarker testing for patients newly diagnosed with nsclc, as well as for patients progressing after treatment with epidermal growth factor receptor (EGFR) inhibitors, is the standard of care in Canada and many parts of the world.

METHODS

A group of thoracic oncology experts in the field of thoracic oncology met to describe the standard for biomarker testing for lung cancer in the Canadian context, focusing on evidence-based recommendations for standard-of-care testing for EGFR, anaplastic lymphoma kinase (ALK), ROS1, BRAF V600 and programmed death-ligand (PD-L1) at the time of diagnosis of advanced disease and EGFR T790M upon progression. As well, additional exploratory molecules and targets are likely to impact future patient care, including MET exon 14 skipping mutations and whole gene amplification, RET translocations, HER2 (ERBB2) mutations, NTRK, RAS (KRAS and NRAS), as well as TP53.

RESULTS

The standard of care must include the incorporation of testing for novel biomarkers as they become available, as it will be difficult for national guidelines to keep pace with technological advances in this area.

CONCLUSIONS

Canadian patients with nsclc should be treated equally; the minimum standard of care is defined in this paper.

Aging and the rise of somatic cancer-associated mutations in normal tissues

DNA mutations are inevitable. Despite proficient DNA repair mechanisms, somatic cells accumulate mutations during development and aging, generating cells with different genotypes within the same individual, a phenomenon known as somatic mosaicism. While the existence of somatic mosaicism has long been recognized, in the last five years, advances in sequencing have provided unprecedented resolution to characterize the extent and nature of somatic genetic variation. Collectively, these new studies are revealing a previously uncharacterized aging phenotype: the accumulation of clones with cancer driver mutations. Here, we summarize the most recent findings, which converge in the novel notion that cancer-associated mutations are prevalent in normal tissue and accumulate with aging.

Transcriptomic Microenvironment of Lung Adenocarcinoma

Background: Tissues surrounding tumors are increasingly studied to understand the biology of cancer development and identify biomarkers.Methods: A unique geographic tissue sampling collection was obtained from patients that underwent curative lobectomy for stage I pulmonary adenocarcinoma. Tumor and nontumor lung samples located at 0, 2, 4, and 6 cm away from the tumor were collected. Whole-genome gene expression profiling was performed on all samples (n = 5 specimens × 12 patients = 60). Analyses were carried out to identify genes differentially expressed in the tumor compared with adjacent nontumor lung tissues at different distances from the tumor as well as to identify stable and transient genes in nontumor tissues with respect to tumor proximity.Results: The magnitude of gene expression changes between tumor and nontumor sites was similar with increasing distance from the tumor. A total of 482 up- and 843 downregulated genes were found in tumors, including 312 and 566 that were consistently differentially expressed across nontumor sites. Twenty-nine genes induced and 34 knocked-down in tumors were also identified. Tumor proximity analyses revealed 15,700 stable genes in nontumor lung tissues. Gene expression changes across nontumor sites were subtle and not statistically significant.Conclusions: This study describes the transcriptomic microenvironment of lung adenocarcinoma and adjacent nontumor lung tissues collected at standardized distances relative to the tumor.Impact: This study provides further insights about the molecular transitions that occur from normal tissue to lung adenocarcinoma and is an important step to develop biomarkers in nonmalignant lung tissues. Cancer Epidemiol Biomarkers Prev; 26(3); 389-96. ©2016 AACR.

Prognostic value of molecular events from negative surgical margin of non-small-cell lung cancer

It is hypothesized that the molecular status in negative surgical margin (NSM) is associated with prognosis of cancer patients. In this study, the prognostic relevance of Epithelial-to-Mesenchymal Transition (EMT) molecular events in NSMs in patients with NSCLC was investigated. EMT model was developed, in which the mesenchymal transition of human immortalized bronchial epithelial cell line was induced by TGF-beta1. Gene expression of EMT-induced cells and NSMs from 60 lung squamous cell carcinoma (SCC) patients was profiled by microarray and validated by quantitative RT-PCR. Two independent cohorts (lung SCC, n = 50; NSCLC, n = 54) were employed to validate the prognostic value of candidate genes. A set of 1490 genes were identified in EMT model in vitro. An EMT-like gene-expression pattern by 33 essential genes was optimized in NSMs, and was significantly associated with tumor progression. The 33 genes also exhibited a site-dependent field cancerization effect in the normal-appearing airways adjacent to NSCLCs. In the independent lung SCC cohort, the EMT-like active pattern indicated poor outcome of patients (n = 50, log-rank p = 0.009). Furthermore, in the NSCLC cohort, patients with EMT-like active pattern had shorter predictive survival time (n = 54, log-rank p = 0.02). In conclusion, the existence of EMT-like gene expression in NSMs, may play critical role in tumor progression and be a potential biomarker for prognosis in patients with NSCLC.

Genomic Landscape Established by Allelic Imbalance in the Cancerization Field of a Normal Appearing Airway

Visually normal cells adjacent to, and extending from, tumors of the lung may carry molecular alterations characteristics of the tumor itself, an effect referred to as airway field of cancerization. This airway field has been postulated as a model for early events in lung cancer pathogenesis. Yet the genomic landscape of somatically acquired molecular alterations in airway epithelia of lung cancer patients has remained unknown. To begin to fill this void, we sought to comprehensively characterize the genomic architecture of chromosomal alterations inducing allelic imbalance (AI) in the airway field of the most common type of lung tumors, non-small cell lung cancer (NSCLC). To do so, we conducted a genome-wide survey of multiple spatially distributed normal-appearing airways, multiregion tumor specimens, and uninvolved normal tissues or blood from 45 patients with early-stage NSCLC. We detected alterations in airway epithelia from 22 patients, with an increased frequency in NSCLCs of squamous histology. Our data also indicated a spatial gradient of AI in samples at closer proximity to the NSCLC. Chromosome 9 displayed the highest levels of AI and comprised recurrent independent events. Furthermore, the airway field AI included oncogenic gains and tumor suppressor losses in known NSCLC drivers. Our results demonstrate that genome-wide AI is common in the airway field of cancerization, providing insights into early events in the pathogenesis of NSCLC that may comprise targets for early treatment and chemoprevention. Cancer Res; 76(13); 3676-83. ©2016 AACR.

Early Events in the Molecular Pathogenesis of Lung Cancer

The majority of cancer-related deaths in the United States and worldwide are attributed to lung cancer. There are more than 90 million smokers in the United States who represent a significant population at elevated risk for lung malignancy. In other epithelial tumors, it has been shown that if neoplastic lesions can be detected and treated at their intraepithelial stage, patient prognosis is significantly improved. Thus, new strategies to detect and treat lung preinvasive lesions are urgently needed in order to decrease the overwhelming public health burden of lung cancer. Limiting these advances is a poor knowledge of the earliest events that underlie lung cancer development and that would constitute markers and targets for early detection and prevention. This review summarizes the state of knowledge of human lung cancer pathogenesis and the molecular pathology of premalignant lung lesions, with a focus on the molecular premalignant field that associates with lung cancer development. Lastly, we highlight new approaches and models to study genome-wide alterations in human lung premalignancy in order to facilitate the discovery of new markers for early detection and prevention of this fatal disease. Cancer Prev Res; 9(7); 518-27. ©2016 AACR.

CT Characteristic of Early Local Recurrence After Resection of the Squamous Cell Carcinoma: Comparison With CT Characteristics of Stump Deformity or Granulation Tissue at Stump Site

The aim of this study is to compare the thin section computed tomography (CT) characteristics of the early local tumor recurrence with those of the stump deformity or granulation tissue after the resection of squamous cell carcinoma (SCC).Twenty-nine consecutive patients with local recurrence after definitive SCC operation from April 2006 to September 2012 were included in our study. Pre- and postoperative CT findings from these patients were retrospectively reviewed and compared with those in the age- and sex-matched 29 patients with the stump deformity or granulation tissue at stump site after definitive SCC operation, by 2 radiologists. We evaluated the initial tumor stage, tumor size, and tumor location in relation with the bronchus on preoperative CT scan. On postoperative CT scan, we evaluated the size, CT characteristics, and involvement pattern of the suspected soft tissue around the stump site, and the distance between surgical staples and soft tissue at the stump site.Tumor stage, tumor size, and tumor location in relation with the bronchus on preoperative CT scan were not significantly different between 2 groups, while lymph node stage was more advanced in the local recurrence group. On postoperative CT scan, the size of suspected soft tissue at stump site is significantly larger, and the distance between stump staples and suspected soft tissue was significantly longer in the local recurrence group than control group (median; 19 mm and 3 mm; 18 mm and 0 mm, respectively, P < 0.001). The univariate analysis showed that the size of soft tissue and the distance between soft tissue and stump site on postoperative CT scan were associated with the predictive factors of local recurrence (P < 0.001). On the receiver-operating characteristic analysis, the optimal cutoffs of the size of soft tissue and the distance between soft tissue and stump staples for determining local tumor recurrence were 6 and 5 mm, respectively.The proper knowledge CT characteristics of local tumor recurrence including the soft tissue size (cut-off, 6 mm) and the distance (cut-off, 5 mm) between soft tissue and stump site will help us achieve the early diagnosis and higher diagnostic rate of locally recurred SCC.

Molecular characterization of the peripheral airway field of cancerization in lung adenocarcinoma

Field of cancerization in the airway epithelium has been increasingly examined to understand early pathogenesis of non-small cell lung cancer. However, the extent of field of cancerization throughout the lung airways is unclear. Here we sought to determine the differential gene and microRNA expressions associated with field of cancerization in the peripheral airway epithelial cells of patients with lung adenocarcinoma. We obtained peripheral airway brushings from smoker controls (n=13) and from the lung contralateral to the tumor in cancer patients (n=17). We performed gene and microRNA expression profiling on these peripheral airway epithelial cells using Affymetrix GeneChip and TaqMan Array. Integrated gene and microRNA analysis was performed to identify significant molecular pathways. We identified 26 mRNAs and 5 miRNAs that were significantly (FDR <0.1) up-regulated and 38 mRNAs and 12 miRNAs that were significantly down-regulated in the cancer patients when compared to smoker controls. Functional analysis identified differential transcriptomic expressions related to tumorigenesis. Integration of miRNA-mRNA data into interaction network analysis showed modulation of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway in the contralateral lung field of cancerization. In conclusion, patients with lung adenocarcinoma have tumor related molecules and pathways in histologically normal appearing peripheral airway epithelial cells, a substantial distance from the tumor itself. This finding can potentially provide new biomarkers for early detection of lung cancer and novel therapeutic targets.

Molecularly targeted therapies in non-small-cell lung cancer annual update 2014

There have been significant advances in the understanding of the biology and treatment of non-small-cell lung cancer (NSCLC) during the past few years. A number of molecularly targeted agents are in the clinic or in development for patients with advanced NSCLC. We are beginning to understand the mechanisms of acquired resistance after exposure to tyrosine kinase inhibitors in patients with oncogene addicted NSCLC. The advent of next-generation sequencing has enabled to study comprehensively genomic alterations in lung cancer. Finally, early results from immune checkpoint inhibitors are very encouraging. This review summarizes recent advances in the area of cancer genomics, targeted therapies, and immunotherapy.

BAI, a novel Cdk inhibitor, enhances farnesyltransferase inhibitor LB42708-mediated apoptosis in renal carcinoma cells through the downregulation of Bcl-2 and c-FLIP (L)

Previously, we reported the potential of a novel Cdk inhibitor, 2-[1,1'-biphenyl]-4-yl-N-[5-(1,1-dioxo-1λ6-isothiazolidin-2-yl)-1H-indazol-3-yl]acetamide (BAI) as a cancer chemotherapeutic agent. In this study, we investigated mechanisms by which BAI modulates FTI-mediated apoptosis in human renal carcinoma Caki cells. BAI synergizes with FTI to activate DEVDase, cleavage of poly ADP-ribose polymerase (PARP), and degradation of various anti-apoptotic proteins in Caki cells. BAI plus LB42708-induced apoptosis was inhibited by pretreatment with pan-caspase inhibitor, z-VAD-fmk, but not by overexpression of CrmA. The ROS scavenger, N-acetylcysteine (NAC) did not reduce BAI plus LB4270-induced apoptosis. Co-treatment of BAI and LB42708 reduced the mitochondrial membrane potential (MMP, ∆Ψm) in a time-dependent manner, and induced release of AIF and cytochrome c from mitochondria in Caki cells. Furthermore, BAL plus LB42708 induced downregulation of anti-apoptotic proteins [c-FLIP (L), c-FLIP (s), Bcl-2, XIAP, and Mcl-1 (L)]. Especially, we found that BAI plus LB42708-induced apoptosis was significantly attenuated by overexpression of Bcl-2 and partially blocked by overexpression of c-FLIP (L). Taken together, our results show that the activity of BAI plus LB42708 modulate multiple components in apoptotic response of human renal Caki cells, and indicate a potential as combinational therapeutic agents for preventing cancer such as renal carcinoma.

Clinicopathology and genetic profile of synchronous multiple small adenocarcinomas: implication for surgical treatment of an uncommon lung malignancy

PURPOSE

Synchronous multiple small adenocarcinomas are detected more frequently than in the past; however, the genetic profile, treatment, and prognosis of patients remain unclear. For treatment decisions and prognostic applications, we evaluated epidermal growth factor receptor (EGFR), p53, and KRAS somatic mutations in synchronous multiple small lung adenocarcinomas.

METHODS

The presence of EGFR, p53, and KRAS somatic mutations was determined in 64 synchronous multiple lung adenocarcinomas ≤2 cm in maximal dimension. Mutational analysis was performed on DNA extracted from paraffin-embedded tumors.

RESULTS

Five-year disease-free survival (DFS) was 86.1 %, and overall survival was 95.8 %. EGFR, p53, and KRAS mutations were detected in 41 (64.1 %), 8 (12.5 %), and 4 (6.3 %) patients, respectively. The high frequency of genetic mutations resulted in a high discrimination rate of tumor clonality (68.8 %; 44/64) in the study group. Fourteen (31.8 %) patients were assessed as having the same clonality, whereas 30 (68.2 %) patients had different clonality, which further supported the concept of field cancerization. Multivariate analysis showed lymph node metastasis (p = 0.003) and smoking (p = 0.011) were significantly correlated with tumor relapse. Surgical method, clonality, and tumor location were not correlated with tumor relapse.

CONCLUSIONS

Whether these tumors are different or the same clonal, sublobar resection of each lesion can achieve long-term DFS and is the treatment of choice for synchronous multiple small lung adenocarcinomas. Patients with lymph node metastasis are at risk of relapse and adjuvant chemotherapy is indicated.

Transcriptomic architecture of the adjacent airway field cancerization in non-small cell lung cancer

BACKGROUND

Earlier work identified specific tumor-promoting abnormalities that are shared between lung cancers and adjacent normal bronchial epithelia. We sought to characterize the yet unknown global molecular and adjacent airway field cancerization (FC) in early-stage non-small cell lung cancer (NSCLC).

METHODS

Whole-transcriptome expression profiling of resected early-stage (I-IIIA) NSCLC specimens (n = 20) with matched tumors, multiple cytologically controlled normal airways with varying distances from tumors, and uninvolved normal lung tissues (n = 194 samples) was performed using the Affymetrix Human Gene 1.0 ST platform. Mixed-effects models were used to identify differentially expressed genes among groups. Ordinal regression analysis was performed to characterize site-dependent airway expression profiles. All statistical tests were two-sided, except where noted.

RESULTS

We identified differentially expressed gene features (n = 1661) between NSCLCs and airways compared with normal lung tissues, a subset of which (n = 299), after gene set enrichment analysis, statistically significantly (P < .001) distinguished large airways in lung cancer patients from airways in cancer-free smokers. In addition, we identified genes (n = 422) statistically significantly and progressively differentially expressed in airways by distance from tumors that were found to be congruently modulated between NSCLCs and normal lung tissues. Furthermore, LAPTM4B, with statistically significantly increased expression (P < .05) in airways with shorter distance from tumors, was upregulated in human immortalized cells compared with normal bronchial epithelial cells (P < .001) and promoted anchorage-dependent and -independent lung cancer cell growth.

CONCLUSIONS

The adjacent airway FC comprises both site-independent profiles as well as gradient and localized airway expression patterns. Profiling of the airway FC may provide new insights into NSCLC oncogenesis and molecular tools for detection of the disease.

Enriching the molecular definition of the airway "field of cancerization:" establishing new paradigms for the patient at risk for lung cancer

The "field of cancerization" refers to histologically normal-appearing tissue adjacent to neoplastic tissue that displays molecular abnormalities, some of which are the same as those of the tumor. Improving our understanding of these molecular events is likely to increase our understanding of carcinogenesis. Kadara and colleagues attempt to characterize the molecular events occurring temporally and spatially within the field of cancerization of patients with early-stage non-small cell lung cancer (NSCLC) following definitive surgery. They followed patients with bronchoscopies annually after tumor resection and extracted RNA from the serial brushings from different endobronchial sites. They then conducted microarray analysis to identify gene expression differences over time and in different sites in the airway. Candidate genes were found that may have biologic relevance to the field of cancerization. For example, expression of phosphorylated AKT and ERK1/2 was found to increase in the airway epithelium with time. Although there are limitations in the study design, this investigation demonstrates the utility of identifying molecular changes in histologically normal airway epithelium in lung cancer. In addition to increasing our understanding of lung cancer biology, studying the field of cancerization has the potential to identify biomarkers from samples obtained in a minimally invasive manner.

Characterizing the molecular spatial and temporal field of injury in early-stage smoker non-small cell lung cancer patients after definitive surgery by expression profiling

Gene expression alterations in response to cigarette smoke have been characterized in normal-appearing bronchial epithelium of healthy smokers, and it has been suggested that adjacent histologically normal tissue displays tumor-associated molecular abnormalities. We sought to delineate the spatial and temporal molecular lung field of injury in smoker patients with early-stage non-small cell lung cancer (NSCLC; n = 19) who were accrued into a surveillance clinical trial for annual follow-up and bronchoscopies within 1 year after definitive surgery. Bronchial brushings and biopsies were obtained from six different sites in the lung at the time of inclusion in the study and at 12, 24, and 36 months after the first time point. Affymetrix Human Gene 1.0 ST arrays were used for whole-transcript expression profiling of airways (n = 391). Microarray analysis identified gene features (n = 1,165) that were nonuniform by site and differentially expressed between airways adjacent to tumors relative to more distant samples as well as those (n = 1,395) that were significantly altered with time up to 3 years. In addition, gene interaction networks mediated by phosphoinositide 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK)1/2 were modulated in adjacent compared with contralateral airways and the latter network with time. Furthermore, phosphorylated AKT and ERK1/2 immunohistochemical expression were significantly increased with time (nuclear pAKT, P = 0.03; cytoplasmic pAKT, P < 0.0001; pERK1/2, P = 0.02) and elevated in adjacent compared with more distant airways (nuclear pAKT, P = 0.04; pERK1/2, P = 0.03). This study highlights spatial and temporal cancer-associated expression alterations in the molecular field of injury of patients with early-stage NSCLCs after definitive surgery that warrant further validation in independent studies.

Field cancerization in non-small cell lung cancer: implications in disease pathogenesis

Lung cancer, of which non-small cell lung cancer (NSCLC) composes the majority, is the leading cause of cancer-related deaths in the United States and worldwide. NSCLCs are tumors with complex biology that we have recently started to understand with the advent of various histological, transcriptomic, genomic, and proteomic technologies. However, the histological and molecular pathogenesis of this malignancy, in particular of adenocarcinomas, is still largely unknown. Earlier studies have highlighted a field cancerization phenomenon in which histologically normal-appearing tissue adjacent to neoplastic and pre-neoplastic lesions display molecular abnormalities, some of which are in common with those in the tumors. This review will summarize advances in understanding the field cancerization phenomenon and the potential relevance of this knowledge to gain important and novel insights into the molecular pathogenesis of NSCLC as well as to subsequent development of biomarkers for early detection of lung cancers and possibly personalized prevention.

The genetics and biology of KRAS in lung cancer

Mutational activation of KRAS is a common oncogenic event in lung cancer and other epithelial cancer types. Efforts to develop therapies that counteract the oncogenic effects of mutant KRAS have been largely unsuccessful, and cancers driven by mutant KRAS remain among the most refractory to available treatments. Studies undertaken over the past decades have produced a wealth of information regarding the clinical relevance of KRAS mutations in lung cancer. Mutant Kras-driven mouse models of cancer, together with cellular and molecular studies, have provided a deeper appreciation for the complex functions of KRAS in tumorigenesis. However, a much more thorough understanding of these complexities is needed before clinically effective therapies targeting mutant KRAS-driven cancers can be achieved.

Pulmonary adenocarcinoma: a renewed entity in 2011

Lung cancer, of which non-small-cell lung cancer comprises the majority, is the leading cause of cancer-related deaths in the United States and worldwide. Lung adenocarcinomas are a major subtype of non-small-cell lung cancers, are increasing in incidence globally in both males and females and in smokers and non-smokers, and are the cause for almost 50% of deaths attributable to lung cancer. Lung adenocarcinoma is a tumour with complex biology that we have recently started to understand with the advent of various histological, transcriptomic, genomic and proteomic technologies. However, the histological and molecular pathogenesis of this malignancy is still largely unknown. This review will describe advances in the molecular pathology of lung adenocarcinoma with emphasis on genomics and DNA alterations of this disease. Moreover, the review will discuss recognized lung adenocarcinoma preneoplastic lesions and current concepts of the early pathogenesis and progression of the disease. We will also portray the field cancerization phenomenon and lineage-specific oncogene expression pattern in lung cancer and how both remerging concepts can be exploited to increase our understanding of lung adenocarcinoma pathogenesis for subsequent development of biomarkers for early detection of adenocarcinomas and possibly personalized prevention.

Ras in cancer and developmental diseases

Somatic, gain-of-function mutations in ras genes were the first specific genetic alterations identified in human cancer about 3 decades ago. Studies during the last quarter century have characterized the Ras proteins as essential components of signaling networks controlling cellular proliferation, differentiation, or survival. The oncogenic mutations of the H-ras, N-ras, or K-ras genes frequently found in human tumors are known to throw off balance the normal outcome of those signaling pathways, thus leading to tumor development. Oncogenic mutations in a number of other upstream or downstream components of Ras signaling pathways (including membrane RTKs or cytosolic kinases) have been detected more recently in association with a variety of cancers. Interestingly, the oncogenic Ras mutations and the mutations in other components of Ras/MAPK signaling pathways appear to be mutually exclusive events in most tumors, indicating that deregulation of Ras-dependent signaling is the essential requirement for tumorigenesis. In contrast to sporadic tumors, separate studies have identified germline mutations in Ras and various other components of Ras signaling pathways that occur in specific association with a number of different familial, developmental syndromes frequently sharing common phenotypic cardiofaciocutaneous features. Finally, even without being a causative force, defective Ras signaling has been cited as a contributing factor to many other human illnesses, including diabetes and immunological and inflammatory disorders. We aim this review at summarizing and updating current knowledge on the contribution of Ras mutations and altered Ras signaling to development of various tumoral and nontumoral pathologies.

Emerging concepts in the pathology and molecular biology of advanced non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is traditionally classified histologically, but until recently, the histologic subtype has had little impact on the selection of therapy. Drugs such as pemetrexed and bevacizumab are indicated for specific NSCLC subtypes, and this type of stratification represents the first step toward individualizing therapy in NSCLC. Beyond histologic features, the status of molecular targets, such as the epidermal growth factor receptor (EGFR) gene, has been shown to correlate with response to treatment with EGFR tyrosine kinase inhibitors in patients with relapsed or refractory disease and in the first-line therapy setting. New therapies targeting the EGFR and other molecular aberrations are under way to help define specific subsets of patients responsive to certain molecularly targeted treatments. The role of pathologists in guiding treatment decisions will increase because molecular profiling, together with pathologic and histologic analysis, represents the future of personalizing medicine for patients with NSCLC.

Evolving concepts in lung carcinogenesis

Lung carcinogenesis is a complex, stepwise process that involves the acquisition of genetic mutations and epigenetic changes that alter cellular processes, such as proliferation, differentiation, invasion, and metastasis. Here, we review some of the latest concepts in the pathogenesis of lung cancer and highlight the roles of inflammation, the "field of cancerization," and lung cancer stem cells in the initiation of the disease. Furthermore, we review how high throughput genomics, transcriptomics, epigenomics, and proteomics are advancing the study of lung carcinogenesis. Finally, we reflect on the potential of current in vitro and in vivo models of lung carcinogenesis to advance the field and on the areas of investigation where major breakthroughs will lead to the identification of novel chemoprevention strategies and therapies for lung cancer.

The field of tissue injury in the lung and airway

The concept of field cancerization was first introduced over 6 decades ago in the setting of oral cancer. Later, field cancerization involving histologic and molecular changes of neoplasms and adjacent tissue began to be characterized in smokers with or without lung cancer. Investigators also described a diffuse, nonneoplastic field of molecular injury throughout the respiratory tract that is attributable to cigarette smoking and susceptibility to smoking-induced lung disease. The potential molecular origins of field cancerization and the field of injury following cigarette smoke exposure in lung and airway epithelia are critical to understanding their potential impact on clinical diagnostics and therapeutics for smoking-induced lung disease.

Lung carcinogenesis: pivotal role of metals in tobacco smoke

Although significant progress has been made in unraveling the molecular mechanisms responsible for tobacco smoke toxicity and carcinogenicity, only limited information is available concerning the mechanisms by which tar particles and the gaseous phase constituents of tobacco smoke participate and contribute to carcinogenic processes in lung cancer. The present review critically evaluates how metals contained in the tar particles and the gaseous phase of tobacco smoke play a leading role in the carcinogenic process, taking into consideration the physiology and pathophysiology of the bronchial epithelium. Overwhelmingly, the published data indicate that the bronchopulmonary epithelial cells may represent the first and most critical line of defense against cigarette smoke.

The farnesyltransferase inhibitor, LB42708, inhibits growth and induces apoptosis irreversibly in H-ras and K-ras-transformed rat intestinal epithelial cells

LB42708 (LB7) and LB42908 (LB9) are pyrrole-based orally active farnesyltransferase inhibitors (FTIs) that have similar structures. The in vitro potencies of these compounds against FTase and GGTase I are remarkably similar, and yet they display different activity in apoptosis induction and morphological reversion of ras-transformed rat intestinal epithelial (RIE) cells. Both FTIs induced cell death despite K-ras prenylation, implying the participation of Ras-independent mechanism(s). Growth inhibition by these two FTIs was accompanied by G1 and G2/M cell cycle arrests in H-ras and K-ras-transformed RIE cells, respectively. We identified three key markers, p21(CIP1/WAF1), RhoB and EGFR, that can explain the differences in the molecular mechanism of action between two FTIs. Only LB7 induced the upregulation of p21(CIP1/WAF1) and RhoB above the basal level that led to the cell cycle arrest and to distinct morphological alterations of ras-transformed RIE cells. Both FTIs successfully inhibited the ERK and activated JNK in RIE/K-ras cells. While the addition of conditioned medium from RIE/K-ras reversed the growth inhibition of ras-transformed RIE cells by LB9, it failed to overcome the growth inhibitory effect of LB7 in both H-ras- and K-ras-transformed RIE cells. We found that LB7, but not LB9, decreased the expression of EGFRs that confers the cellular unresponsiveness to EGFR ligands. These results suggest that LB7 causes the induction of p21(CIP1/WAF1) and RhoB and downregulation of EGFR that may serve as critical steps in the mechanism by which FTIs trigger irreversible inhibitions on the cell growth and apoptosis in ras-transformed cells.

Exploiting the PI3K/AKT pathway for cancer drug discovery

Evolving studies with several different targeted therapeutic agents are demonstrating that patients with genomic alterations of the target, including amplification, translocation and mutation, are more likely to respond to the therapy. Recent studies indicate that numerous components of the phosphatidylinositol-3-kinase (PI3K)/AKT pathway are targeted by amplification, mutation and translocation more frequently than any other pathway in cancer patients, with resultant activation of the pathway. This warrants exploiting the PI3K/AKT pathway for cancer drug discovery.

P53and K-rasmutations are frequent events in microscopically negative surgical margins from patients with nonsmall cell lung carcinoma

BACKGROUND

The objective of the current study was to determine whether tumor cells harboring P53 and K-ras mutations could be detected in histopathologically tumor-free surgical margins in patients with nonsmall cell lung carcinoma who underwent complete pulmonary resection.

METHODS

In 118 consecutive patients, DNA obtained from primary tumors and from surgical margins was extracted for molecular analysis. A fragment of P53 gene encompassing exons 5-8 and codon 12 of the K-ras gene were amplified with the polymerase chain reaction technique and were assayed for the presence of mutations.

RESULTS

P53 and K-ras mutations were found in 30% and 39% of primary tumors, respectively, and in 11 (9%) and 22 (18%) apparently tumor-free surgical margins, respectively. At least 1 of those mutations was found in surgical margins in 29 patients (25%), and both mutations were found in 2 patients (1.7%). P53 mutations in surgical margins accompanied mutations in primary tumors in 9 of 35 patients (26%), and K-ras mutations accompanied mutations in primary tumors in 20 of 46 patients (44%). Among patients with either mutation in primary tumors, the incidence of at least 1 mutation in surgical margins was 43% (28 of 65 patients). In four patients, mutations (two K-ras mutations and two P53 mutations) were found in surgical margins despite the absence of the corresponding mutations in primary tumors. The presence of mutations in primary tumors and in surgical margins was not related significantly to clinical characteristics or to patient outcomes.

CONCLUSIONS

P53 and K-ras mutations are frequent events in surgical margins determined to be tumor free on light microscopy. The clinical relevance of these findings remains to be established.

Mutant frequencies and mutation spectra of dimethylnitrosamine (DMN) at the lacI and cII loci in the livers of Big Blue transgenic mice

The lacI gene in Big Blue transgenic rodents has traditionally been used as a surrogate gene for in vivo mutations. Recently, a more efficient and less expensive assay involving direct selection in the smaller lambda cII gene has been developed. Little is known, however, about the comparative sensitivity of the two loci or their influence on the recovered mutation spectrum following mutagen treatment. We have compared the mutation frequency (MF) and mutational spectrum (MS) of lacI and cII from the same DNA samples isolated from the liver of control and dimethylnitrosamine (DMN)-treated mice. A three-fold (p<0.01) increase in the MF was observed at both loci in the DMN-treated group compared to the corresponding control groups. While the DMN-induced mutation spectrum at lacI was significantly different from its corresponding spontaneous mutation spectrum (p<0.001), the mutation spectrum at cII (p>0.28) was not. The mutation spectra at the two loci from the DMN-treated mice resembled each other but the 4, 2.5 and 12-fold increase in the mutation frequency of A:T>T:A transversions, single base deletions and deletions of more than four base pairs, respectively, at lacI, altered the spectra significantly (p<0.007). The number of mutations of these classes at cII was also increased, but the fractions were lower than at lacI. The spontaneous mutation spectra at the cII and lacI loci resembled each other except for the seven-fold increase in G:C<C:G transversions in the cII spectrum resulting in a significant difference (p<0.0001) between the spectra. Our initial data indicates that although cII is as sensitive to mutation induction as lacI, fewer sites are available for certain classes of mutations to be manifest resulting in an apparent lack in change in the mutation spectrum.

Differential frequencies of p16(INK4a) promoter hypermethylation, p53 mutation, and K-ras mutation in exfoliative material mark the development of lung cancer in symptomatic chronic smokers

PURPOSE

The aim of this study was to investigate the frequency of three (epi)genetic alterations (p53 and K-ras mutations and p16(INK4a) promoter hypermethylation) in symptomatic chronic smokers compared with patients with lung cancer and to evaluate the use of exfoliative material for such analyses.

PATIENTS AND METHODS

Fifty-one patients with histologically confirmed lung cancer and 25 chronic smokers (> 20 pack-years) were investigated for mutations in the K-ras (codon 12) and p53 (codons 248, 249, and 273) genes and for allelic hypermethylation of the p16(INK4a) gene. DNA was isolated from sputum and bilateral bronchial lavage, and brushings were taken at bronchoscopy.

RESULTS

Forty-one genetic lesions were detected within exfoliative material from the group of 51 patients with lung cancer and 10 lesions in the chronic smoker group. K-ras mutations occurred exclusively in the lung cancer group, whereas p53 mutations and p16(INK4a) promoter hypermethylation were also found in chronic smokers. Three of eight chronic smokers who harbored an (epi)genetic alteration were subsequently diagnosed with lung cancer. Analysis of sputum yielded information equivalent to that of samples obtained during bronchoscopy.

CONCLUSION

p16(INK4a) promoter hypermethylation and p53 mutations can occur in chronic smokers before any clinical evidence of neoplasia and may be indicative of an increased risk of developing lung cancer or of early disease. K-ras mutations occur exclusively in the presence of clinically detectable neoplastic transformation. Molecular analysis of sputum for such markers may provide an effective means of screening chronic smokers to enable earlier detection and therapeutic intervention of lung cancer.

Early detection and prevention of lung cancer

Lung cancer remains the leading cause of cancer death in the United States and is one of the world's leading causes of preventable death. Technologic advances have brought new modalities that may be useful for the early detection of lung cancer. However, because of the large number of persons at increased risk for lung cancer, screening is a formidable task. There are several risk factors that can be identified, including potential susceptibility factors, which may aid in pinpointing individuals who need to participate in regular screening programs. Aside from recognized environmental exposures including cigarette smoking, there are a number of genetic and metabolic susceptibility factors that have been examined. These include polymorphisms in the cytochrome p450 enzymes and the metabolizing capability of glutathione s-transferase or acetylation. Additionally, defects in DNA repair and in bleomycin sensitivity assays may also aid in identifying individuals who are at an increased risk for lung cancer. Additional work has been done in the area of characterizing the molecular alterations in the bronchial epithelium in high-risk smokers. This manuscript addresses only selected molecular alterations that have been examined in preneoplastic bronchial epithelium. In addition to mutations in the k-ras oncogene and the p53 gene, which are frequently seen in malignancy, alterations in the p16 gene, microsatellite instability and loss of heterozygocity are also promising potential markers of preneoplasia. The hnRNP A2/B1 gene also shows some promising increased expression in preneoplasia. Lung cancer prevention has made some strides. A number of trials with molecular and morphologic intermediate endpoints have been conducted and have suggested that some of the molecular alterations and morphologic alterations are reversible. However, the rate of spontaneous regression of these lesions is, as yet, uncharacterized. Two recent large studies, the beta-carotene and retinol efficacy trial (CARET) trial conducted in the United States and the Alpha-Tocopherol Beta Carotene (ATBC) trial conducted in Finland, both demonstrated an unexpected increased risk for lung cancer associated with beta-carotene supplementation. The EUROSCAN trial evaluation of vitamin A and N-acetylcystine also showed no benefit to supplementation in reducing risk for lung cancer. Results from the Intergroup study of 1 3-cis-retinoic acid are pending, and plans are underway for an Intergroup trial studying high selenium yeast to reduce lung cancer risk. Hopefully, the combination of identifying markers of increased risk among the numerous current and former smokers will identify high-risk populations to participate in future trials of promising agents that may lead to reduction in incidence and mortality of the leading cause of cancer death.

Potential biomarkers for the early detection of lung cancer

Lung cancer remains the leading cause of cancer death among men and women in the United States. Early detection of premalignant lesions provides the possibility of treatment at earlier stages. Because malignancy develops from genetic alterations, the early detection of these genetic changes should be associated with the earliest clues to transformation. This article presents an overview of detection of molecular markers and their relevance to lung cancer. In the future, such molecular markers may play a role in guiding therapy for lung cancer.

K-ras gene point mutation in neogenetic lesions of subpleural fibrotic lesions: either an early genetic event in lung cancer development or a non-specific genetic change during the inflammatory reparative process

In the present study, K-ras mutation was investigated in 156 neogenetic epithelia that appeared in the lesion of subpleural fibrosis in order to elucidate the close relationship of lung cancer development with pulmonary interstitial pneumonia. The neogenetic epithelia were histologically subclassified into six types: (i) ciliated bronchial epithelium (CBE); (ii) squamous metaplastic epithelium (SME); (iii) cuboidal immature epithelium (CIE); (iv) stratified immature epithelium (SIE); (v) mucus cell epithelium (MCE); and (vi) intestinal metaplastic epithelium (IME). K-ras mutation was detected in 9.6% of neogenetic epithelia overall; 21% of CIE, 12% of SIE, 16% of SME, but not in other types of neogenetic epithelia. Immunohistochemically, CIE and SIE frequently expressed surfactant apoprotein and SME was characteristic to carcinoembryonic antigen expression. According to Ki-67 immunostain, CIE, SIE and SME are likely to grow faster than other histological types of epithelia. K-ras mutation was seen exclusively in codon 12 with predominant G to A and G to C substitutions without any G to T transversions, results which are somewhat different to previous studies in lung cancers. The present study clearly demonstrated that K-ras mutation appeared in certain histological types of neogenetic epithelia, but raised the question of whether K-ras mutation in neogenetic epithelia during the inflammatory reparative process might be an early genetic event in lung carcinogenesis.

Synchronous and metachronous lung carcinomas: molecular evidence for multicentricity

The present study is aimed to evaluate the genetic evidence for multicentricity of synchronous and metachronous multiple lung carcinomas. Nineteen cases of synchronous multiple lung carcinomas and 11 cases of metachronous multiple lung carcinomas were analyzed for p53 protein overexpression by immunohistochemistry (DO-7) and for genetic abnormality of the p53 gene by loss of heterozygosity (LOH) at chromosome 17p and by polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis. They were also analyzed for K-ras mutation. DNA from three patients was also sequenced by the dideoxy sequencing method to confirm the presence of mutations and determine the base substitutions. Different spectrums of genetic changes, which were evaluated by a combination of p53 mutation, LOH at chromosome 17p and p53 overexpression, were observed in 11 of 19 cases of synchronous multiple lung carcinomas (57.9%) in the present study. Similarly, five of 11 cases of metachronous multiple lung carcinomas (45.4%) showed a different pattern of genetic changes. The present data suggest that some of the multiple carcinomas have different clonal origins, although their histological types are identical, and support the use of genetic markers in the differential diagnosis between metastasis and second primary carcinoma of the lung.