Lung cancer: genetics of risk and advances in chemoprevention

Repurposing quinacrine for treatment-refractory cancer

Quinacrine, also known as mepacrine, has originally been used as an antimalarial drug for close to a century, but was recently rediscovered as an anticancer agent. The mechanisms of anticancer effects of quinacrine are not well understood. The anticancer potential of quinacrine was discovered in a screen for small molecule activators of p53, and was specifically shown to inhibit NFκB suppression of p53. However, quinacrine can cause cell death in cells that lack p53 or have p53 mutations, which is a common occurrence in many malignant tumors including high grade serous ovarian cancer. Recent reports suggest quinacrine may inhibit cancer cell growth through multiple mechanisms including regulating autophagy, FACT (facilitates chromatin transcription) chromatin trapping, and the DNA repair process. Additional reports also suggest quinacrine is effective against chemoresistant gynecologic cancer. In this review, we discuss anticancer effects of quinacrine and potential mechanisms of action with a specific focus on gynecologic and breast cancer where treatment-refractory tumors are associated with increased mortality rates. Repurposing quinacrine as an anticancer agent appears to be a promising strategy based on its ability to target multiple pathways, its selectivity against cancer cells, and the synergistic cytotoxicity when combined with other anticancer agents with limited side effects and good tolerability profile.

The pivotal role of pathology in the management of lung cancer

The last decade has seen significant advances in our understanding of lung cancer biology and management. Identification of key driver events in lung carcinogenesis has contributed to the development of targeted lung cancer therapies, heralding the era of personalised medicine for lung cancer. As a result, histological subtyping and molecular testing has become of paramount importance, placing increasing demands on often small diagnostic specimens. This has triggered the review and development of the first structured classification of lung cancer in small biopsy/cytology specimens and a new classification of lung adenocarcinoma from the IASLC/ATS/ERS. These have enhanced the clinical relevance of pathological diagnosis, and emphasise the role of the modern surgical pathologist as an integral member of the multidisciplinary team, playing a crucial role in clinical trials and determining appropriate and timely management for patients with lung cancer.

Detection and minimally invasive treatment of early squamous lung cancer

Non-small cell lung cancer (NSCLC) is the most common cause of cancer deaths worldwide. The majority of patents presenting with NSCLC have advanced disease, which precludes curative treatment. Early detection and treatment might result in the identification of more patients with early central lung cancer and improve survival. In addition, the study of early lung cancer improves understanding of lung carcinogenesis and might also reveal new treatment targets for advanced lung cancer. Bronchoscopic investigation of the central airways can reveal both early central lung cancer in situ (stage 0) and other preinvasive lesions such as dysplasia. In the current review we discuss the detection of early squamous lung cancer, the natural history of preinvasive lesions and whether biomarkers can be used to predict progression to cancer. Finally we will review the staging and management of preinvasive lung cancer lesions and the different therapeutic modalities that are available.

Lung cancer chemoprevention: current status and future prospects

Lung cancer is the leading cause of cancer death worldwide, making it an attractive disease for chemoprevention. Although avoidance of tobacco use and smoking cessation will have the greatest impact on lung cancer development, chemoprevention could prove to be very effective, particularly in former smokers. Chemoprevention is the use of agents to reverse or inhibit carcinogenesis and has been successfully applied to other common malignancies. Despite prior studies in lung cancer chemoprevention failing to identify effective agents, we now have the ability to identify high-risk populations, and our understanding of lung tumour and premalignant biology continues to advance. There are distinct histological lesions that can be reproducibly graded as precursors of non-small-cell lung cancer and similar precursor lesions exist for adenocarcinoma. These premalignant lesions are being targeted by chemopreventive agents in current trials and will continue to be studied in the future. In addition, biomarkers that predict risk and response to targeted agents are being investigated and validated. In this Review, we discuss the principles of chemoprevention, data from preclinical models, completed clinical trials and observational studies, and describe new treatments for novel targeted pathways and future chemopreventive efforts.

A gene expression profile test to resolve head & neck squamous versus lung squamous cancers

Background

The differential diagnosis between metastatic head & neck squamous cell carcinomas (HNSCC) and lung squamous cell carcinomas (lung SCC) is often unresolved because the histologic appearance of these two tumor types is similar. We have developed and validated a gene expression profile test (GEP-HN-LS) that distinguishes HNSCC and lung SCC in formalin-fixed, paraffin-embedded (FFPE) specimens using a 2160–gene classification model.

Methods

The test was validated in a blinded study using a pre-specified algorithm and microarray data files for 76 metastatic or poorly-differentiated primary tumors with a known HNSCC or lung SCC diagnosis.

Results

The study met the primary Bayesian statistical endpoint for acceptance. Measures of test performance include overall agreement with the known diagnosis of 82.9% (95% CI, 72.5% to 90.6%), an area under the ROC curve (AUC) of 0.91 and a diagnostics odds ratio (DOR) of 23.6. HNSCC (N = 38) gave an agreement with the known diagnosis of 81.6% and lung SCC (N = 38) gave an agreement of 84.2%. Reproducibility in test results between three laboratories had a concordance of 91.7%.

Conclusion

GEP-HN-LS can aid in resolving the important differential diagnosis between HNSCC and lung SCC tumors.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1753227817890930

Cancer prevention interdisciplinary education program at Purdue University: overview and preliminary results

Cancer prevention is a broad field that crosses many disciplines; therefore, educational efforts to enhance cancer prevention research focused on interdisciplinary approaches to the field are greatly needed. In order to hasten progress in cancer prevention research, the Cancer Prevention Internship Program (CPIP) at Purdue University was designed to develop and test an interdisciplinary curriculum for undergraduate and graduate students. The hypothesis was that course curriculum specific to introducing interdisciplinary concepts in cancer prevention would increase student interest in and ability to pursue advanced educational opportunities (e.g., graduate school, medical school). Preliminary results from the evaluation of the first year which included ten undergraduate and five graduate students suggested that participation in CPIP is a positive professional development experience, leading to a significant increase in understanding of interdisciplinary research in cancer prevention. In its first year, the CPIP project has created a successful model for interdisciplinary education in cancer prevention research.

Beyond DNA binding - a review of the potential mechanisms mediating quinacrine's therapeutic activities in parasitic infections, inflammation, and cancers

This is an in-depth review of the history of quinacrine as well as its pharmacokinetic properties and established record of safety as an FDA-approved drug. The potential uses of quinacrine as an anti-cancer agent are discussed with particular attention to its actions on nuclear proteins, the arachidonic acid pathway, and multi-drug resistance, as well as its actions on signaling proteins in the cytoplasm. In particular, quinacrine's role on the NF-κB, p53, and AKT pathways are summarized.

Association studies of excision repair cross-complementation group 1 (ERCC1) haplotypes with lung and head and neck cancer risk in a Caucasian population

BACKGROUND

The formation of bulky DNA adducts caused by diol epoxide derivatives of polycyclic aromatic hydrocarbons has been associated with tobacco-induced cancers, and inefficient repair of such adducts by the nucleotide excision repair (NER) system has been linked to increased risk of tobacco-induced lung and head and neck (H&N) cancers. The human excision repair cross-complementation group 1 (ERCC1) protein is essential for a functional NER system and genetic variation in ERCC1 may contribute to impaired DNA repair capacity and increased lung and H&N cancer risk.

METHODS

In order to comprehensively capture common genetic variation in the ERCC1 gene, Caucasian data from the International HapMap project was used to assess linkage disequilibrium and choose four tagSNPs (rs1319052, rs3212955, rs3212948, and rs735482) in the ERCC1 gene to genotype 452 lung cancer cases, 175 H&N cancer cases, and 790 healthy controls. Haplotypes were estimated using expectation maximization (EM) algorithm, and haplotype association with cancer was investigated using Haplo.stats software adjusting for known covariates.

RESULTS

The genotype and haplotype frequencies matched previous estimates from Caucasians. There was no significant difference in the prevalence of rs1319052, rs3212955, rs3212948, and rs735482 when comparing lung or H&N cancer cases with controls (p-values>0.05). Similarly, there was no association between ERCC1 haplotypes and lung or H&N cancer susceptibility in this Caucasian population (p-values>0.05). No associations were found when stratifying lung cancer cases by histology, sex, smoking status, or smoking intensity.

CONCLUSIONS

This study suggests that ERCC1 polymorphisms and haplotypes do not play a role in lung and H&N cancer susceptibility in Caucasians.

Chemoprevention of lung carcinogenesis in addicted smokers and ex-smokers

Chemoprevention of lung carcinogenesis is one approach to controlling the epidemic of lung cancer caused by cigarette smoking. The target for chemoprevention should be the activities of the multiple carcinogens, toxicants, co-carcinogens, tumour promoters and inflammatory compounds in cigarette smoke. At present there are many agents, both synthetic and naturally occurring, that prevent lung tumour development in well-established animal models. It seems likely that logically constructed mixtures of these agents, developed from the ground up, will be necessary for the prevention of lung carcinogenesis.

Genetic variants in cell cycle control pathway confer susceptibility to lung cancer

PURPOSE

To test the hypothesis that common sequence variants of cell cycle control genes may affect lung cancer predisposition.

EXPERIMENTAL DESIGN

We explored lung cancer risk associations of 11 polymorphisms in seven cell cycle genes in a large case-control study including 1,518 Caucasian lung cancer patients and 1,518 controls.

RESULTS

When individuals with variant-containing genotypes were compared with homozygous wild-type carriers, a significantly increased lung cancer risk was identified for polymorphisms in p53 intron 6 [rs1625895; odds ratio (OR), 1.29; 95% confidence interval (95% CI), 1.08-1.55] and in p27 5' untranslated region (UTR; rs34330; OR, 1.27; 95% CI, 1.01-1.60). Compared with homozygous wild-types, the homozygous variant genotypes of STK15 F31I and CCND1 G870A were associated with a significantly altered lung cancer risk with ORs of 0.58 (95% CI, 0.37-0.90) and 1.26 (95% CI, 1.03-1.53), respectively. To assess the cumulative effects of all the investigated polymorphisms on lung carcinogenesis, we conducted a combined analysis and found that compared with low-risk individuals with few adverse alleles, individuals with more adverse alleles had an increased risk in a significant dose-dependent manner (P(trend) = 0.041). This pattern was more evident in ever smokers (P(trend) = 0.037), heavy smokers (P(trend) = 0.020), and older subjects (P(trend) = 0.011). Higher-order gene-gene interactions were evaluated using the classification and regression tree analysis, which indicated that STK15 F31I and p53 intron 6 polymorphisms might be associated with lung carcinogenesis in never/light-smokers and heavy smokers, respectively.

CONCLUSIONS

Our results suggest that cell cycle gene polymorphisms and smoking may function collectively to modulate the risk of lung cancer.

Chemoprevention of lung cancers: lessons from CARET, the beta-carotene and retinol efficacy trial, and prospects for the future

The objective of this paper was to review the strategies for lung cancer chemoprevention. A retrospective assessment of the major findings from the most informative lung cancer chemoprevention clinical trials [alpha-tocopherol (vitamin E), beta-carotene trial and beta-carotene and retinol efficacy trial] was employed. Both trials and many others showed no benefit from what was once the prime candidate for lung cancer chemoprevention, beta-carotene. Furthermore, both trials found that beta-carotene, alone or in combination with vitamin E or retinyl palmitate, increased the incidence of lung cancers and the total and cardiovascular mortality rates. In conclusion, design, conduct, documentation, relationships with participants, and preparedness for unexpected findings are all important for chemoprevention research. Trials are necessary to test inferences from observational epidemiology and animal models. Multiple classes of promising agents are available for evaluation and for eventual randomized trials.

The association between the anti-inflammatory protein CC10 and smoking status among participants in a chemoprevention trial

CC10, the secretory product of bronchiolar Clara cells, is infrequently expressed in non-small cell lung cancer (NSCLC), and its overexpression in NSCLC cell lines results in a less malignant phenotype. CC10 levels in bronchoalveolar lavage fluid (BAL) and serum are significantly lower in current smokers than healthy nonsmokers, but the effect of long-term smoking cessation on CC10 is unknown. We measured CC10 in baseline BAL and plasma collected from current (n = 81) and former (n = 23) smokers participating in a chemoprevention trial. Former smokers had significantly higher plasma CC10 levels compared with current smokers [mean, 62.1 ng/mL (95% CI, 43.0-81.2); range, 23.0-175.0 ng/mL for former smokers; and mean, 37.1 ng/mL (95% CI, 29.8-44.4); range, 5.0-171.0 ng/mL for current smokers; P < 0.001]. BAL CC10 levels also trended in the same direction. A significant positive correlation was found between CC10 plasma and BAL levels. After adjustment for age, sex, and pack-years of cigarette consumption, former smokers had 1.70 (95% CI, 1.23-2.36) times higher plasma CC10 levels than current smokers (P < 0.01), whereas former smokers also had nonsignificantly higher baseline BAL CC10 levels compared with current smokers [adjusted mean ratio (95% CI), 1.60 (0.92-2.80), P = 0.094 and 1.35 (0.86-2.10), P = 0.193 for the absolute and normalized BAL CC10, respectively]. These results show that sustained smoking cessation is associated with higher plasma CC10 levels, suggesting that at least some of the damage associated with tobacco smoke may be repaired by long-term smoking cessation.

Lung carcinoma in African Americans

Lung carcinoma is the most commonly diagnosed cancer and the leading cause of cancer deaths in the US. It accounts for 12% of all cancers diagnosed worldwide, making it the most common malignancy, other than nonmelanoma skin cancer. A new focus has emerged involving the role of race and ethnicity in lung carcinoma. Current health statistics data demonstrate striking disparities, which are most evident between African American patients and their white counterparts. This disparity is greatest among male patients, where statistically significant differences are seen not only in lung cancer incidence and risk, but also in survival and treatment outcomes. Several hypotheses that attempt to explain this disparity include genetic, cultural and socioeconomic differences, in addition to differences in tobacco use and exposure. Current evidence does not clearly identify the reasons for this observed disparity, or the role the aforementioned factors play in the development and overall outcomes of people with lung cancer in these populations. This disease continues to pose a considerable public health burden and more research is needed to improve understanding of the disparity of lung carcinoma statistics among African Americans. This review summarizes the existing body of knowledge regarding lung carcinoma in African Americans and attempts to identify promising areas for future investigation and intervention.

Lung Cancer in Never Smokers: A Review

Lung cancer is the leading cause of cancer-related death in the United States. Although tobacco smoking accounts for the majority of lung cancer, approximately 10% of patients with lung cancer in the United States are lifelong never smokers. Lung cancer in the never smokers (LCINS) affects women disproportionately more often than men. Only limited data are available on the etiopathogenesis, molecular abnormalities, and prognosis of LCINS. Several etiologic factors have been proposed for the development of LCINS, including exposure to radon, cooking fumes, asbestos, heavy metals, and environmental tobacco smoke, human papillomavirus infection, and inherited genetic susceptibility. However, the relative significance of these individual factors among different ethnic populations in the development of LCINS has not been well-characterized. Adenocarcinoma is the predominant histologic subtype reported with LCINS. Striking differences in response rates and outcomes are seen when patients with advanced non–small-cell lung cancer (NSCLC) who are lifelong never smokers are treated with epidermal growth factor receptor tyrosine kinase (EGFR-TK) inhibitors such as gefitinib or erlotinib compared with the outcomes with these agents in patients with tobacco-associated lung cancer. Interestingly, the activating mutations in the EGFR-TK inhibitors have been reported significantly more frequently in LCINS than in patients with tobacco-related NSCLC. This review will summarize available data on the epidemiology, risk factors, molecular genetics, management options, and outcomes of LCINS.

Lung cancer risk prediction: a tool for early detection

Although 45% of men and 39% of women will be diagnosed with cancer in their lifetime, it is difficult to predict which individuals will be affected. For some cancers, substantial progress in individual risk estimation has already been made. However, relatively few models have been developed to predict lung cancer risk beyond effects of age and smoking. This paper reviews published models for lung cancer risk prediction, discusses their potential contribution to clinical and research settings and suggests improvements to the risk modeling strategy for lung cancer. The sensitivity and specificity of existing cancer risk models is less than optimal. Improvement in individual risk prediction is important for selection of individuals for prevention or early detection interventions. In addition to smoking, factors related to occupational exposure, personal medical history and family history of cancer can add to the predictive power. A good risk prediction model is one that can identify a small fraction of the population in which a large proportion of the disease cases will occur. In the future, genetic and other biological markers are likely to be useful, although they will require rigorous evaluation. Validation is essential to establish the predictive effect and for ongoing monitoring of the model's continued relevance.

Tumor-suppressive effects of MBP-1 in non-small cell lung cancer cells

Lung cancer is the leading cause of cancer death among both men and women. Only approximately 15% of people diagnosed with non-small cell lung cancer (NSCLC) survive this disease beyond 5 years. Thus, novel therapeutic strategies are urgently needed to improve the clinical management of this devastating disease. We have previously shown the antiproliferative effect of MBP-1 on several human cancer cells. In this study, we have examined the potential of MBP-1 as a gene therapeutic candidate in regression of non-small cell lung tumor growth. We have observed that exogenous expression of MBP-1 in NSCLC cells (H1299) induces massive cell death. To determine the gene therapeutic potential of MBP-1, replication-deficient recombinant adenovirus expressing MBP-1 was given intratumorally in human lung cancer xenografts in nude mice. Our results showed a significant regression of lung tumor growth and prolonged survival on treatment with MBP-1 compared with the control groups (saline or dl312). Subsequently, the mechanism of MBP-1-mediated H1299 cell death was investigated. Our results suggested that MBP-1 induced poly(ADP-ribose) polymerase cleavage in H1299 cells; however, treatment with pan-caspase inhibitor did not protect against MBP-1-induced cell death. Cells transduced with MBP-1 displayed early plasma membrane permeability, mitochondrial damage without cytochrome c release, and extensive cytoplasmic vacuolation, yielding a morphotype that is typical of necrosis. Taken together, this study suggests that MBP-1 expression induces a novel form of necrosis-like cell death and MBP-1 could be a potential gene therapeutic candidate against non-small cell lung tumor growth.

Pathogenesis of lung cancer: 100 year report

Over the past 100 years, our understanding of the pathogenesis of lung cancer has advanced impressively. Environmental carcinogens and a gene locus determining susceptibility have been identified. The pathology of lung cancer has been classified into categories with major clinical implications. The cellular and molecular genetic changes underlying lung cancer have become better understood over the past 25 years, but the stepwise progression of respiratory epithelium from normal to neoplastic is not yet well demarcated, limiting abilities to advance early detection and chemoprevention. The translation of improved understanding of dominant signal transduction pathways in lung cancer to rationally designed therapeutic strategies has had recent successes, demonstrating a proof of principle for targeted therapy in lung cancer. Improvement in overall patient outcomes has been stubbornly slow and will require concerted efforts.