Analysis of cell cycle regulator proteins in non-small cell lung cancer

The Role of Death-Associated Protein Kinase-1 in Cell Homeostasis-Related Processes

Tremendous amount of financial resources and manpower have been invested to understand the function of numerous genes that are deregulated during the carcinogenesis process, which can be targeted for anticancer therapeutic interventions. Death-associated protein kinase 1 (DAPK-1) is one of the genes that have shown potential as biomarkers for cancer treatment. It is a member of the kinase family, which also includes Death-associated protein kinase 2 (DAPK-2), Death-associated protein kinase 3 (DAPK-3), Death-associated protein kinase-related apoptosis-inducing kinase 1 (DRAK-1) and Death-associated protein kinase-related apoptosis-inducing kinase 2 (DRAK-2). DAPK-1 is a tumour-suppressor gene that is hypermethylated in most human cancers. Additionally, DAPK-1 regulates a number of cellular processes, including apoptosis, autophagy and the cell cycle. The molecular basis by which DAPK-1 induces these cell homeostasis-related processes for cancer prevention is less understood; hence, they need to be investigated. The purpose of this review is to discuss the current understanding of the mechanisms of DAPK-1 in cell homeostasis-related processes, especially apoptosis, autophagy and the cell cycle. It also explores how the expression of DAPK-1 affects carcinogenesis. Since deregulation of DAPK-1 is implicated in the pathogenesis of cancer, altering DAPK-1 expression or activity may be a promising therapeutic strategy against cancer.

Identification of Flavone Derivative Displaying a 4'-Aminophenoxy Moiety as Potential Selective Anticancer Agent in NSCLC Tumor Cells

Five heterocyclic derivatives were synthesized by functionalization of a flavone nucleus with an aminophenoxy moiety. Their cytotoxicity was investigated in vitro in two models of human non-small cell lung cancer (NSCLC) cells (A549 and NCI-H1975) by using MTT assay and the results compared to those obtained in healthy fibroblasts as a non-malignant cell model. One of the aminophenoxy flavone derivatives (APF-1) was found to be effective at low micromolar concentrations in both lung cancer cell lines with a higher selective index (SI). Flow cytometric analyses showed that APF-1 induced apoptosis and cell cycle arrest in the G2/M phase through the up-regulation of p21 expression. Therefore, the aminophenoxy flavone-based compounds may be promising cancer-selective agents and could serve as a base for further research into the design of flavone-based anticancer drugs.

Targeting Cell Cycle Progression in HER2+ Breast Cancer: An Emerging Treatment Opportunity

The development of HER2-targeted therapies has dramatically improved patient survival and patient management and increased the quality of life in the HER2+ breast cancer patient population. Due to the activation of compensatory pathways, patients eventually suffer from resistance to HER2-directed therapies and develop a more aggressive disease phenotype. One of these mechanisms is the crosstalk between ER and HER2 signaling, especially the CDK4/6-Cyclin D-Rb signaling axis that is commonly active and has received attention for its potential role in regulating tumor progression. CDK 4/6 inhibitors interfere with the binding of cell-cycle-dependent kinases (CDKs) with their cognate partner cyclins, and forestall the progression of the cell cycle by preventing Rb phosphorylation and E2F release that consequentially leads to cancer cell senescence. CDK 4/6 inhibitors, namely, palbociclib, ribociclib, and abemaciclib, in combination with anti-estrogen therapies, have shown impressive outcomes in hormonal receptor-positive (HR+) disease and have received approval for this disease context. As an extension of this concept, preclinical/clinical studies incorporating CDK 4/6 inhibitors with HER2-targeted drugs have been evaluated and have shown potency in limiting tumor progression, restoring therapeutic sensitivity, and may improving the management of the disease. Currently, several clinical trials are examining the synergistic effects of CDK 4/6 inhibitors with optimized HER2-directed therapies for the (ER+/-) HER2+ population in the metastatic setting. In this review, we aim to interrogate the burden of HER2+ disease in light of recent treatment progress in the field and examine the clinical benefit of CDK 4/6 inhibitors as a replacement for traditional chemotherapy to improve outcomes in HER2+ breast cancer.

Induction of G2/M Cell Cycle Arrest via p38/p21Waf1/Cip1-Dependent Signaling Pathway Activation by Bavachinin in Non-Small-Cell Lung Cancer Cells

Lung cancer is the most commonly diagnosed malignant cancer in the world. Non-small-cell lung cancer (NSCLC) is the major category of lung cancer. Although effective therapies have been administered, for improving the NSCLC patient’s survival, the incident rate is still high. Therefore, searching for a good strategy for preventing NSCLC is urgent. Traditional Chinese medicine (TCM) are brilliant materials for cancer chemoprevention, because of their high biological safety and low cost. Bavachinin, which is an active flavanone of Proralea corylifolia L., possesses anti-inflammation, anti-angiogenesis, and anti-cancer activities. The present study’s aim was to evaluate the anti-cancer activity of bavachinin on NSCLC, and its regulating molecular mechanisms. The results exhibited that a dose-dependent decrease in the cell viability and colony formation capacity of three NSCLC cell lines, by bavachinin, were through G2/M cell cycle arrest induction. Meanwhile, the expression of the G2/M cell cycle regulators, such as cyclin B, p-cdc2^Y15, p-cdc2^T161, and p-wee1, was suppressed. With the dramatic up-regulation of the cyclin-dependent kinase inhibitor, p21^Waf1/Cip1, the expression and association of p21^Waf1/Cip1 with the cyclin B/cdc2 complex was observed. Silencing the p21^Waf1/Cip1 expression significantly rescued bavachinin-induced G2/M cell accumulation. Furthermore, the expression of p21^Waf1/Cip1 mRNA was up-regulated in bavachinin-treated NSCLC cells. In addition, MAPK and AKT signaling were activated in bavachinin-added NSCLC cells. Interestingly, bavachinin-induced p21^Waf1/Cip1 expression was repressed after restraint p38 MAPK activation. The inhibition of p38 MAPK activation reversed bavachinin-induced p21^Waf1/Cip1 mRNA expression and G2/M cell cycle arrest. Collectively, bavachinin-induced G2/M cell cycle arrest was through the p38 MAPK-mediated p21^Waf1/Cip1-dependent signaling pathway in the NSCLC cells.

Metastatic HPV-Associated Oropharyngeal Versus Primary Pulmonary Squamous Cell Carcinoma: is p16 Immunostain Useful?

The lungs are a common site of metastasis of head and neck (H&N) squamous cell carcinomas (SCC). This study attempts to define p16 immunoexpression and presence of HPV in primary SCC of the lung and determine their usefulness in discriminating between primary lung SCC and metastasis from HPV-associated oropharyngeal primary. Pathology archives were searched for patients with SCC of the lung without SCC elsewhere. Tissue microarray was constructed and immunohistochemistry performed using anti-p40 and anti-p16 antibodies. All cases were tested for HPV viral proteins E6/E7 by RNA in situ hybridization (ISH) and available positive cases for HPV DNA by polymerase chain reaction (PCR). Eight of 25 (32%) showed cytoplasmic and nuclear expression of p16: 2 (8%) strong and 2 (8%) moderate in > 70% of tumor cells; 1 (4%) strong, 1 (4%) moderate, and 1 (4%) weak in 50-70% of tumor cells; 1 (4%) weak in < 50% of tumor cells. E6/E7 mRNA ISH was negative in all cases. Seven of 8 (87.5%) p16-expressing cases were available for testing by HPV PCR; all were negative for HPV DNA. A retrospective control group of 12 patients with possible SCC metastatic to lung was also identified; high-risk HPV DNA was present in 3, confirming metastasis. p16 expression in lung SCC is not uncommon and may not discriminate between primary pulmonary SCC and metastasis from HPV-associated oropharyngeal primary. Confirmatory HPV testing (high risk HPV DNA or E6/E7 mRNA) is recommended to differentiate metastasis from oropharyngeal primary from two separate primaries.

Palbociclib treatment alters nucleotide biosynthesis and glutamine dependency in A549 cells

BACKGROUND

Aberrant activity of cell cycle proteins is one of the key somatic events in non-small cell lung cancer (NSCLC) pathogenesis. In most NSCLC cases, the retinoblastoma protein tumor suppressor (RB) becomes inactivated via constitutive phosphorylation by cyclin dependent kinase (CDK) 4/6, leading to uncontrolled cell proliferation. Palbociclib, a small molecule inhibitor of CDK4/6, has shown anti-tumor activity in vitro and in vivo, with recent studies demonstrating a functional role for palbociclib in reprogramming cellular metabolism. While palbociclib has shown efficacy in preclinical models of NSCLC, the metabolic consequences of CDK4/6 inhibition in this context are largely unknown.

METHODS

In our study, we used a combination of stable isotope resolved metabolomics using [U-13C]-glucose and multiple in vitro metabolic assays, to interrogate the metabolic perturbations induced by palbociclib in A549 lung adenocarcinoma cells. Specifically, we assessed changes in glycolytic activity, the pentose phosphate pathway (PPP), and glutamine utilization. We performed these studies following palbociclib treatment with simultaneous silencing of RB1 to define the pRB-dependent changes in metabolism.

RESULTS

Our studies revealed palbociclib does not affect glycolytic activity in A549 cells but decreases glucose metabolism through the PPP. This is in part via reducing activity of glucose 6-phosphate dehydrogenase, the rate limiting enzyme in the PPP. Additionally, palbociclib enhances glutaminolysis to maintain mitochondrial respiration and sensitizes A549 cells to the glutaminase inhibitor, CB-839. Notably, the effects of palbociclib on both the PPP and glutamine utilization occur in an RB-dependent manner.

CONCLUSIONS

Together, our data define the metabolic impact of palbociclib treatment in A549 cells and may support the targeting CDK4/6 inhibition in combination with glutaminase inhibitors in NSCLC patients with RB-proficient tumors.

Loss of Rb1 Enhances Glycolytic Metabolism in Kras-Driven Lung Tumors In Vivo

Dysregulated metabolism is a hallmark of cancer cells and is driven in part by specific genetic alterations in various oncogenes or tumor suppressors. The retinoblastoma protein (pRb) is a tumor suppressor that canonically regulates cell cycle progression; however, recent studies have highlighted a functional role for pRb in controlling cellular metabolism. Here, we report that loss of the gene encoding pRb (Rb1) in a transgenic mutant Kras-driven model of lung cancer results in metabolic reprogramming. Our tracer studies using bolus dosing of [U-¹³C]-glucose revealed an increase in glucose carbon incorporation into select glycolytic intermediates. Consistent with this result, Rb1-depleted tumors exhibited increased expression of key glycolytic enzymes. Interestingly, loss of Rb1 did not alter mitochondrial pyruvate oxidation compared to lung tumors with intact Rb1. Additional tracer studies using [U-¹³C,¹⁵N]-glutamine and [U-¹³C]-lactate demonstrated that loss of Rb1 did not alter glutaminolysis or utilization of circulating lactate within the tricarboxylic acid cycle (TCA) in vivo. Taken together, these data suggest that the loss of Rb1 promotes a glycolytic phenotype, while not altering pyruvate oxidative metabolism or glutamine anaplerosis in Kras-driven lung tumors.

Loss of parkin reduces lung tumor development by blocking p21 degradation

Several epidemiological studies have demonstrated the reciprocal relationship between the development of cancer and Parkinson’s disease (PD). However, the possible mechanisms underlying this relationship remain unclear. To identify this relationship, we first compared lung tumor growth in parkin knockout (KO) mice and wild-type (WT) mice. Parkin KO mice showed decreased lung tumor growth and increased expression of p21, a cell cycle arrester, as compared with WT mice. We also found that parkin interacts with p21, resulting in its degradation; however, parkin KO, knockdown, as well as mutation (R275W or G430D) reduced the degradation of p21. We investigated whether parkin KO increases the association of p21 with proliferating cell nuclear antigen (PCNA) or CDK2 by reducing p21 degradation, and, thus, arresting the cell cycle. The interaction between p21 and PCNA or CDK2 was also enhanced by parkin knockdown, and this increased interaction induced sub G0/G1 arrest, leading to cell death. Therefore, our data indicate that parkin KO reduces the development of lung tumors via cell cycle arrest by blocking the degradation of p21. These findings suggest that PD could be associated with lower lung cancer incidence.

A multi-omics approach for identifying important pathways and genes in human cancer

Background

Cancer develops when pathways controlling cell survival, cell fate or genome maintenance are disrupted by the somatic alteration of key driver genes. Understanding how pathway disruption is driven by somatic alterations is thus essential for an accurate characterization of cancer biology and identification of therapeutic targets. Unfortunately, current cancer pathway analysis methods fail to fully model the relationship between somatic alterations and pathway activity.

Results

To address these limitations, we developed a multi-omics method for identifying biologically important pathways and genes in human cancer. Our approach combines single-sample pathway analysis with multi-stage, lasso-penalized regression to find pathways whose gene expression can be explained largely in terms of gene-level somatic alterations in the tumor. Importantly, this method can analyze case-only data sets, does not require information regarding pathway topology and supports personalized pathway analysis using just somatic alteration data for a limited number of cancer-associated genes. The practical effectiveness of this technique is illustrated through an analysis of data from The Cancer Genome Atlas using gene sets from the Molecular Signatures Database.

Conclusions

Novel insights into the pathophysiology of human cancer can be obtained from statistical models that predict expression-based pathway activity in terms of non-silent somatic mutations and copy number variation. These models enable the identification of biologically important pathways and genes and support personalized pathway analysis in cases where gene expression data is unavailable.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2476-8) contains supplementary material, which is available to authorized users.

CDKN1A-interacting zinc finger protein 1 is a novel biomarker for lung squamous cell carcinoma

CDKN1A-interacting zinc finger protein 1 (CIZ1), a nuclear protein that participates in DNA replication, is involved in the pathogenesis of several types of cancer. However, the role of CIZ1 in lung squamous cell carcinoma (LSCC) is not fully understood. In the present study, the expression of CIZ1 in tissue microarrays and surgical samples of human LSCCs was examined. CIZ1 expression was found to be significantly increased in LSCC tissues compared with adjacent tissues or normal controls, whereas expression of a CIZ1-interacting protein, p21^Cip1/Waf1, was decreased. CIZ1 staining intensity and CIZ1-positive vascular invasion were positively correlated with at least two categories of the Tumor-Node-Metastasis (TNM) staging system (T stage, N stage or TNM stage). It was also observed that CIZ1 was specifically expressed in the vascular cells of LSCC tissues. These results indicate that overexpression of CIZ1 may contribute to the growth and angiogenesis of LSCC, thus CIZ1 could represent a biomarker for diagnosis and a target for therapeutic intervention.

Prediction of recurrence in early stage non-small cell lung cancer using computer extracted nuclear features from digital H&E images

Identification of patients with early stage non-small cell lung cancer (NSCLC) with high risk of recurrence could help identify patients who would receive additional benefit from adjuvant therapy. In this work, we present a computational histomorphometric image classifier using nuclear orientation, texture, shape, and tumor architecture to predict disease recurrence in early stage NSCLC from digitized H&E tissue microarray (TMA) slides. Using a retrospective cohort of early stage NSCLC patients (Cohort #1, n = 70), we constructed a supervised classification model involving the most predictive features associated with disease recurrence. This model was then validated on two independent sets of early stage NSCLC patients, Cohort #2 (n = 119) and Cohort #3 (n = 116). The model yielded an accuracy of 81% for prediction of recurrence in the training Cohort #1, 82% and 75% in the validation Cohorts #2 and #3 respectively. A multivariable Cox proportional hazard model of Cohort #2, incorporating gender and traditional prognostic variables such as nodal status and stage indicated that the computer extracted histomorphometric score was an independent prognostic factor (hazard ratio = 20.81, 95% CI: 6.42–67.52, P < 0.001).

Mdig, a lung cancer-associated gene, regulates cell cycle progression through p27(KIP1)

Mineral dust-induced gene (mdig) can accelerate cell proliferation. The aim of this study is to investigate the mechanism by which mdig regulates cell proliferation. A549 cells were transfected with siRNA specifically targeting mdig. Cell proliferation and cell cycle progression were measured using MTT assay and cell cycle analysis, respectively. Furthermore, real-time reverse transcription quantitative-polymerase chain reaction (RT-qPCR) was performed in A549 cells transfected with mdig siRNA to examine the expression levels of the cell cycle related genes such as p18(INK4c), p19(INK4d), p21(WAF/CIP1), p27(KIP1), p57(KIP2), cyclin D1, and cyclin E. To further explore the effect of mdig on p27(KIP1), the expression levels of total p27(KIP1) and its subtypes pT187-p27(KIP1) and pS10-p27(KIP1) were assessed by Western blotting. In vivo, Western blotting was performed to check the expression levels of mdig and p27(KIP1) in human lung cancer tissues, para-cancerous normal lung tissues, and para-bronchial stumps. Knockdown of mdig induced increases in p27(KIP1), both on mRNA and protein levels. Furthermore, the phosphorylation of p27(KIP1) at its Thr187 site was also inhibited. Importantly, in lung cancer tissues, upregulation of mdig expression accompanies with the downregulation of p27(KIP1) expression and in bronchial stump, vice versa. The data suggest that mdig-mediated inhibition of p27(KIP1) is important for cell proliferation and tumor formation and reveal therapeutic potential of p27(KIP1) for lung cancer.

Cyclin-dependent kinase-specific activity predicts the prognosis of stage I and stage II non-small cell lung cancer

BACKGROUND

Lung cancer is one of the leading causes of cancer death worldwide. Even with complete resection, the prognosis of early-stage non-small cell lung cancer is poor due to local and distant recurrence, and it remains unclear which biomarkers are clinically useful for predicting recurrence or for determining the efficacy of chemotherapy. Recently, several lines of evidence have indicated that the enzymatic activity of cyclin-dependent kinases could be a clinically relevant prognostic marker for some cancers. We investigated whether the specific activity of cyclin-dependent kinases 1 and 2 could predict recurrence or death in early non-small cell lung cancer patients.

METHODS

Patients with newly diagnosed, pathologically confirmed non-small cell lung cancer were entered into this blinded cohort study. The activity of cyclin-dependent kinases was determined in 171 samples by the C2P® assay, and the results were subjected to statistical analysis with recurrence or death as a clinical outcome.

RESULTS

The Cox proportional hazards model revealed that the activity of cyclin-dependent kinase 1, but not 2, was a predictor of recurrence, independent of sex, age, and stage. By contrast, cyclin-dependent kinase 2 activity was a predictor of death, independent of sex and stage.

CONCLUSION

This study suggested the possible clinical use of cyclin-dependent kinase 1 as a predictor of recurrence and cyclin-dependent kinase 2 as a predictor of overall survival in early-stage non-small cell lung cancer. Thus, a combination of activity of cyclin-dependent kinases 1 and 2 is useful in decision-making regarding treatment strategies for non-small cell lung cancer after surgery.

Relationship of immunohistochemical biomarker expression and lymph node involvement in patients undergoing surgical treatment of NSCLC with long-term follow-up

We try to identify the relationship between immunohistochemical marker expression and lymph node involvement in a cohort of 282 patients followed for 5 years after curative resection for NSCLC. In 189 patients (67%), lymph nodes were unaffected while 93 patients (33%) showed nodal involvement. The expression of 15 molecular markers was determined from each patient by tissue-array immunohistochemistry. Univariate analysis indicated significantly higher expression of E-cadherin, γ-catenin, p27, and p53 in patients with lymph node involvement. In those with unaffected nodes, p16 and Rb were expressed. E-cadherin expression was related to a 50% mortality reduction in patients with node involvement (hazard ratio (HR) 0.5; p = 0.017). c-erbB-2 expression was correlated with a 3.4-fold increase in mortality compared to patients without expression of this marker in subjects without node involvement (HR 3.41; p = 0.017). Multivariate analysis identified c-erbB-2 (HR 2.22; p = 0.089) and p27 (HR 1.44; p = 0.019) as prognostics of mortality while Rb (HR 0.74) indicated a good prognosis. The expression of proteins encoded by oncogenes and tumor suppressor genes was different according to lymph node involvement. The increased mortality related to c-erbB-2 expression in patients with unaffected lymph nodes would suggests a need for adjuvant treatment.

β-Escin inhibits NNK-induced lung adenocarcinoma and ALDH1A1 and RhoA/Rock expression in A/J mice and growth of H460 human lung cancer cells

Lung cancer is the leading cause of cancer-related deaths. β-Escin, a triterpene saponin isolated from horse chestnut seeds, was tested for inhibition of lung adenoma and adenocarcinoma induced by the tobacco carcinogen 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in female A/J mice; and its possible mode of action was evaluated using the H460 human lung cancer cell line. At 6 weeks of age, 35 mice were fed AIN-76A-modified diet, and one week later, lung tumors were induced with a single intraperitoneal (i.p.) injection of 10 μmol NNK/mouse. Three weeks after the NNK treatment, groups of mice were fed either control or experimental diets containing 500 ppm for 20 weeks (10 control, 5 β-escin) or 36 weeks (15 control, 5 β-escin) and evaluated for lung tumor via histopathologic methods. Administration of 500 ppm β-escin significantly suppressed lung tumor (adenoma + adenocarcinoma) formation by more than 40% (P < 0.0015) at 20 weeks and by 53.3% (P < 0.0001) at 37 weeks. β-Escin inhibited NNK-induced lung adenocarcinoma formation by 65% (P < 0.001) at 20 weeks and by 53% (P < 0.0001) at 37 weeks. Immunohistochemical analysis revealed that lung tumors from mice exposed to β-escin showed significantly reduced aldehyde dehydrogenase (ALDH)1A1 and phospho-Akt (p-Akt) expression when compared with those in mice fed control diet. Aldefluor assay for ALDH revealed that among H460 lung cancer cells treated with different concentrations of β-escin (0-40 μmol/L), the subpopulation of cells with elevated ALDH activity was inhibited significantly. Our findings suggest that β-escin inhibits tobacco carcinogen-induced lung tumor formation by modulating ALDH1A1-positive cells and RhoA/Rock signaling.

A comprehensive analysis of p16 expression, gene status, and promoter hypermethylation in surgically resected non-small cell lung carcinomas

INTRODUCTION

The role of p16 is gaining importance in non-small cell lung cancer (NSCLC) because of epigenetic therapy options. Further insight into the significance of protein expression, gene status and promoter methylation is needed and has the potential to optimize existing treatment strategies.

METHODS

This population-based study analyzes p16 in 383 surgically resected non-small cell lung carcinomas brought into a standardized tissue microarray platform. Immunohistochemistry and fluorescence in situ hybridization were performed. For selected cases, p16 promoter hypermethylation was assessed by a pyrosequencing assay. Extensive clinical data and a postoperative follow-up period of 15 years enabled detailed correlations.

RESULTS

Loss of p16 expression is a common event in NSCLC (232/365, 64%), especially in squamous cell carcinomas (97/115, 84%) in contrast to adenocarcinomas (93/186, 50%). Loss of p16 expression was associated with poorer survival time for the entire cohort and for certain subgroups including men, age younger than 65 years, smokers, early tumor stage, adenocarcinoma, and large-cell carcinoma. Promoter hypermethylation was absent for cases expressing p16 but was commonly observed when (heterozygous) p16 gene deletions were present and in cases negative for p16.

CONCLUSION

Our comprehensive data would be compatible with a two-step process leading to loss of p16 expression in NSCLC. Hypermethylation of the promoter region may represent an early event, followed by heterozygous deletion of the p16 locus. Because of the possibility of detection of hypermethylated gene regions, these data may lead to the identification of specific patient subgroups more likely to benefit from upcoming demethylating treatment strategies.

Tumor suppressors and cell-cycle proteins in lung cancer

The cell cycle is the cascade of events that allows a growing cell to duplicate all its components and split into two daughter cells. Cell cycle progression is mediated by the activation of a highly conserved family of protein kinases, the cyclin-dependent kinases (CDKs). CDKs are also regulated by related proteins called cdk inhibitors grouped into two families: the INK4 inhibitors (p16, p15, p19, and p18) and the Cip/Kip inhibitors (p21, p27, and p53). Several studies report the importance of cell-cycle proteins in the pathogenesis and the prognosis of lung cancer. This paper will review the most recent data from the literature about the regulation of cell cycle. Finally, based essentially on the data generated in our laboratory, the expression, the diagnostic, and prognostic significance of cell-cycle molecules in lung cancer will be examined.

Prognostic impact of S100A9 overexpression in non-small cell lung cancer

S100 proteins have been implicated in the progression and metastasis of several cancers. Among the S100 family, S100A9 is reportedly expressed in non-small cell lung cancer (NSCLC), though the clinical significance and prognostic value of S100A9 expression in NSCLC remains unclear. The aim of the present study was to examine the relationship between S100A9 expression and prognosis in NSCLC patients. S100A9 expression was evaluated by immunohistochemical staining. Seventy patients with NSCLC who had undergone lung resection were enrolled in the study. Overexpression of S100A9 was observed in 38 (54.3%) patients. Kaplan-Meier analysis showed that, following surgery, patients overexpressing S100A9 had a significantly lower 5-year overall survival rate than patients with weak or no expression of S100A9 (P=0.005). This finding was also observed in pathological stage IA patients (P=0.03). Multivariate Cox regression analysis revealed overexpression of S100A9 to be an independent factor predictive of poor disease outcome (hazard ratio, 0.3; 95% confidence interval, 0.1-0.8; P=0.02). Our results suggest that overexpression of S100A9 is associated with a poor prognosis among NSCLC patients and could serve as a marker identifying patients who are at high risk, even at an early pathological stage.

Reduced p21(WAF1/CIP1) via alteration of p53-DDX3 pathway is associated with poor relapse-free survival in early-stage human papillomavirus-associated lung cancer

PURPOSE

DDX3 alteration has been shown to participate in hepatocellular tumorigenesis via p21(WAF1/CIP1) (p21) deregulation. We observed that DDX3 and p21 expression in lung tumors was negatively associated with E6 expression. Therefore, the aim of this study was to clarify whether deregulation of p21 by DDX3 via an E6-inactivated p53 pathway would enhance tumor progression in HPV-associated lung cancers.

EXPERIMENTAL DESIGN

Real-time PCR, luciferase assays, immunoprecipitation, and chromatin immunoprecipitation (ChIP) were performed to determine whether DDX3 was regulated by p53 to synergistically enhance p21 transcriptional activity. Cell proliferation was examined by cell counting and colony formation assays. DDX3 and p21 expression were evaluated in 138 lung tumors by real-time PCR and immunohistochemistry. The prognostic value of p21 expression on relapse-free survival (RFS) was analyzed by Kaplan-Meier analysis.

RESULTS

Real-time PCR, luciferase assays, and ChIP assays indicated that three putative p53 binding sites, located at -1,080/-1,070, -695/-685, and -283/-273 on the DDX3 promoter, were required for DDX3 transcription. DDX3 deregulation by the E6-inactivated p53 pathway could promote cell proliferation and the ability to form colonies via reduced Sp1 binding activity on the p21 promoter. Among tumors, p21 expression was positively associated with DDX3 expression and negatively related with E6 expression, particularly in early-stage (I + II) tumors. Interestingly, low p21 expression was associated with a poor RFS in early-stage lung cancer.

CONCLUSION

The reduction of p21 by the alteration of the p53-DDX3 pathway plays an essential role in early-stage HPV-associated lung tumorigenesis and is correlated with poor RFS of lung cancer patients.

Potentially functional polymorphisms in cell cycle genes and the survival of non-small cell lung cancer in a Chinese population

The cell cycle governs the proliferation and growth of cells and is strictly controlled by some regulators including cyclins, CDKs and CKIs. Germ-line and somatic mutations in cell cycle genes were frequently observed in a subset of cancers including non-small cell lung cancer (NSCLC). In this study, we hypothesized that potentially functional single nucleotide polymorphisms (SNPs) in cell cycle genes may contribute to the prognosis of NSCLC in China. 54 potentially functional polymorphisms in key cell cycle genes (CDK1, CDK2, CDK4, CDK6, CDK7, CCND1, CCND2, CCND3, CCNE1, CCNA1, CCNA2, CCNB1, CCNH, p15, p16, p18, p19, p21, p27, Cdc25A and Cdc25B) were genotyped by using Illumina SNP genotyping platform to evaluate their associations with survival of NSCLC in a clinical cohort of 568 patients. We found that p18 rs3176447 variant genotypes were significantly associated with the decreased risk of death of NSCLC patients (adjusted HR=0.74, 95% CI=0.57-0.97 in an additive model; adjusted HR=0.76, 95% CI=0.55-0.97 in a dominant model); however, p21 rs2395655 variant genotypes were significantly associated with the increased risk of death (adjusted HR=1.21, 95% CI=1.02-1.42 in an additive model; adjusted HR=1.38, 95% CI=1.07-1.78 in a recessive model). Furthermore, the combined effect of unfavorable genotypes for these two SNPs was more prominent in patients with squamous cell carcinoma, late stage and without chemo- or radio-therapy. Although the exact biological function remains to be explored, our findings suggest possible association of polymorphisms of p18 and p21 with the prognosis of NSCLC in a Chinese population. Further large and functional studies are needed to confirm our findings.

New predictors of response to neoadjuvant chemotherapy and survival for invasive thymoma: a retrospective analysis

BACKGROUND

Cell-cycle protein (p27, p21, and p53) expression can predict response to neoadjuvant chemotherapy and prognosis in some neoplasms. This study evaluated whether these markers could also be effective in invasive thymoma during a multimodality treatment.

METHODS

Between 1989 and 2008, 33 patients with invasive thymoma underwent surgical resection after neoadjuvant chemotherapy. Expression of p27, p21, and p53 was assessed using immunohistochemistry in specimens retrieved pre and post chemotherapy. Factors influencing response to neoadjuvant chemotherapy and survival were investigated by univariate and multivariate analysis. Good response was defined as complete disappearance of tumor at imaging or necrosis >90% at pathologic studies.

RESULTS

Twelve patients disclosed an imaging good response. Complete resection was possible in 17 patients, 9 of whom had presented imaging good response and 11 of whom had revealed pathologic good response. On univariate analysis both imaging and pathologic poor responses were significantly associated with incomplete resection (P = 0.04 and P = 0.03, respectively) and preneoadjuvant triple combination of p27 low, p21 low, and p53 high expressions (P = 0.001 and P < 0.0001, respectively), the last factor being the only one selected on logistic regression (P = 0.01 and P = 0.005, respectively). Long-term survival analysis was negatively influenced by triple combination of p27, p21, and p53 (P < 0.0001) and incomplete resection (P < 0.0001), which were also selected on Cox's regression (P = 0.004 and P = 0.02, respectively).

CONCLUSIONS

The triple combination of p27 low, p21 low, and p53 high expressions was the most significant predictor of imaging and pathologic poor responses to neoadjuvant chemotherapy in invasive thymoma. This combination together with incomplete resection was also the most significant negative predictor of long-term survival.

New biomarkers for lung cancer

IMPORTANCE OF THE FIELD

Despite many efforts to improve early detection, lung cancer remains the leading cause of cancer deaths. Stage is the main determinant of prognosis and the basis for deciding treatment options. Screening tests for lung cancer have not been successful so far.

AREAS COVERED IN THE REVIEW

The article reviews the available literature related to biomarkers in use at present and those that could be used for early diagnosis, staging, prognosis, response to therapy and prediction of recurrence. The single biomarkers are analysed, divided according to the technological methods used and the locations of sampling.

WHAT THE READER WILL GAIN

The reader will gain knowledge on biomarkers in use and those now under study. The reader will also gain insights into the difficulties pertaining to the development of biomarkers, results reproducibility and clinical application.

TAKE HOME MESSAGE

Although some markers seem to be promising, at present there is no consensus on the proven value of their clinical use in lung cancer. The future lies probably in a panel of biomarkers instead of individual assays, or in predictive models derived from the integration of clinical variables and gene expression profiles.

Silibinin inhibits human nonsmall cell lung cancer cell growth through cell-cycle arrest by modulating expression and function of key cell-cycle regulators

Recent studies show that silibinin possesses a strong antineoplastic potential against many cancers; however, its efficacy and underlying molecular mechanisms in nonsmall cell lung cancer (NSCLC) are not well defined. Herein, we assessed silibinin activity on prime endpoints and key molecular targets such as cell number, cell-cycle progression, and cell-cycle regulatory molecules in three cell lines representing different NSCLC subtypes, namely large cell carcinoma cells (H1299 and H460) and a bronchioalveolar carcinoma cell line (H322). Silibinin treatment (10-75 microM) inhibited cell growth and targeted cell-cycle progressing causing a prominent G(1) arrest in dose- and time-dependent manner. In mechanistic studies, silibinin (50-75 microM) modulated the protein levels of cyclin-dependent kinases (CDKs) (4, 6, and 2), cyclins (D1, D3, and E), CDKIs (p18/INK4C, p21/Cip1, and p27/Kip1) in a differential manner in these three cell lines. Consistent with these observations, silibinin caused a reduction in kinase activity of CDK4 and 2 in all cell lines except no effect on CDK4 kinase activity in H460 cells, and concomitantly reduced Rb phosphorylation. Together, for the first time, these results identify potential molecular targets and anticancer effects of silibinin in NSCLC cells representing different NSCLC subtypes.

Role of cell cycle regulators in lung carcinogenesis

Cellular division is an ordered, tightly regulated process involving multiple checkpoints that assess extracellular growth signals, cell size and DNA integrity. Progression throughout the cell cycle is based on the activation of different CDK-cyclin complexes that prevent cells from entering into a new phase until thay have successfully complete the previous one. In addition, a series of cell cycle checkpoints are designed to preserve genome integrity and chromosomal stability. Neoplastic lung cells develop the ability to bypass several of these checkpoints, and tumor cell proliferation is frequently associated with genetic or epigenetic alterations in key regulators of the cell cycle. The goal of this review is to summarize the knowledge about the dysregulation of major cell cycle regulators in lung cancer pathogenesis and to discuss the use of these proteins as targets for therapeutic intervention.

Cyclin D1 overexpression, p16 loss, and pRb inactivation play a key role in pulmonary carcinogenesis and have a prognostic implication for the long-term survival in non-small cell lung carcinoma patients

PURPOSE

We investigated the immunoexpressions of cyclin D1, cyclin-dependent kinase inhibitor p16 and phosphorylated retinoblastoma (p-pRb) proteins in non-small cell lung carcinoma (NSCLC) to demonstrate their key roles in tumorigenesis, their relationship with the clinicopathologic factors, and their prognostic influences on the long-term survival.

MATERIALS AND METHODS

115 surgically resected NSCLCs were immunohistochemically stained for the G(1)/S cell cycle proteins, with using a tissue microarray. The correlation between their immunoexpressions and the clinicopathologic prognostic factors, their inter-relationships and their single or combined effects on the long-term survival (over 5 years) were statistically analyzed by SPSS15.0.

RESULTS

Loss of p16 was found in 75% of the cases and cyclin D1 overexpression and phosphorylated pRb (p-pRb) were found in 64% and 46%, respectively. Cyclin D1 overexpression was correlated with the p16 loss and pRb inactivation by phosphorylation. The p16 loss was tightly associated with p-pRb. The Kaplan-Meier survival curves disclosed that the cyclin D1-positive group and the p16-negative group showed a rapid decline of survival at the point of about 5 years after surgery and thereafter. The combined actions of cyclin D1 overexpression, loss of p16 and pRb inactivation tended to have an adverse influence on the prolonged survival.

CONCLUSIONS

The observation that cyclin D1 overexpression, p16 loss and pRb inactivation were largely found in NSCLCs suggests that they play an important role in pulmonary carcinogenesis. Also, their inverse or positive correlations indicate that the G(1)/S cell cycle proteins may act alternatively or synergistically on the mechanisms by which tumor cells escape the G(1) restriction point. Finally, their solitary or combined actions might have a long-term effect on the survival.

Potential biomarkers involving IKK/RelA signal in early stage non-small cell lung cancer

The clinical relevance of nuclear factor kappaB (NF-kappaB) and its regulatory molecules on prognosis of patient with early stages of non-small cell lung cancer (NSCLC), remains unclear. Therefore, we conducted biomarker analyses with survival in patients with stages I and II NSCLC. Tumor samples were collected from 88 patients with early-stage NSCLC (stages I, II). A minimum follow-up period of 5 years was required. RelA, phosphorylated I kappaB (pI kappaB alpha), pIKK alpha/beta were detected by immunostaining. NF-kappaB DNA binding activity was assessed by electrophoretic mobility shift assay. Association of clinical and pathologic variables (e.g. sex, age, pathologic stage) with relevant molecules was determined by Pearson's chi(2) test or Fisher's exact test. Survival analysis based on single expression of RelA, pI kappaB alpha, pIKK alpha/beta as well as composite expressions were evaluated using Cox proportional hazards regression models, and log rank test followed Kaplan-Meier estimates. RelA, pI kappaB alpha, pIKK alpha/beta were observed as increased expression in NSCLC tissues compared with adjacent normal tissues and normal lung tissues. These molecules were associated with tumor-node-metastasis stages, T stages and histological status, respectively. Among the molecules analyzed, RelA and pI kappaB alpha-positive were statistically significant predictors of patient death in the entire patient population adjusted by age, gender and smoking status; furthermore both RelA and pI kappaB alpha-positive was the strongest prognostic indicators of poor prognosis by univariate and multivariate analyses. Borderline positive correlations were observed between RelA and pI kappaB alpha or pIKK alpha/beta expression. In this cohort of early-stage NSCLC patients, molecular markers, especially composite application of multiple biomarkers (both nuclear RelA and cytoplasmic pI kappaB-alpha expression) that independently predict overall survival have been identified.

Combined prognostic value of both RelA and IkappaB-alpha expression in human non-small cell lung cancer

BACKGROUND

We sought to investigate the prognostic significance of nuclear factor (NF)-kappaB activity, especially nuclear RelA and IkappaB-alpha expression patterns, in non-small cell lung cancer (NSCLC).

METHODS

A total of 116 patients with pathologically confirmed stage I to II NSCLC were included. Immunohistochemical analysis and electrophoretic mobility shift assays of NF-kappaB were performed to determine RelA and phosphorylated IkappaB-alpha staining, and DNA binding activity of NF-kappaB in human NSCLC. Downstream genes, including VEGF and IL-8, were also assessed. The prognostic significance of a single expression of RelA, phosphorylated IkappaB-alpha, and b-composite expressions was evaluated by Cox proportional hazard regression models and by Kaplan-Meier survival analyses. Correlation between RelA/IkappaB-alpha expression status and clinicopathological features of NSCLC was also analyzed.

RESULTS

NF-kappaB DNA binding activity, VEGF, and IL-8 showed correlation with nuclear RelA and cytoplasmic pIkappaB-alpha expression. Expression of nuclear RelA/NF-kappaB showed an increase in NSCLC tissue compared with adjacent normal tissue and normal lung tissue. There was a positive correlation between NF-kappaB activation (nuclear translocation of RelA) and tumor clinicopathological features such as tumor grade, including T stages, N stages, and tumor, node, metastasis system stages, smoking status, and age. Positive correlation was observed between nuclear RelA and cytoplasmic pIkappaB-alpha. Both nuclear RelA and cytoplasmic pIkappaB-alpha were associated with poor prognosis by univariate and multivariate analyses.

CONCLUSIONS

Nuclear RelA and cytoplasmic pIkappaB-alpha expression are associated with a poorer prognosis in NSCLC patients. In particular, composite application of these two biomarkers might be of greater value than application of a single marker to identify patients at high risk, even at an early clinical stage.

Prognostic implications of cell cycle-related proteins in primary resectable pathologic N2 nonsmall cell lung cancer

BACKGROUND

Patients who have pathologic N2 (pN2) nonsmall cell lung cancer (pN2 NSCLC) represent a heterogeneous group with regard to prognosis and treatment. Molecular features of NSCLC seem to be of interest. For the current study, to select an appropriate therapeutic strategy for each patient, patients with N2 NSCLC were stratified into homogenous subgroups according to the expression profiles of cell cycle-related markers.

METHODS

The expression levels of retinoblastoma protein (pRb), cyclin D1, p16, p53, and p21 proteins and values of the Ki-67 labeling index were evaluated in 61 primary surgically resected tumor specimens from patients with pN2 NSCLC using immunohistochemistry. The prognostic impact of these markers on overall survival was analyzed in both univariate and multivariate analyses.

RESULTS

In univariate analysis, p21, p16, and Ki-67 were correlated significantly with survival. In multivariate analysis, only p21 and p16 influenced survival. Indeed, the group of patients with pN2 NSCLC who were positive for p21 and p16 had the most favorable overall survival (P = .001) and were correlated significantly with the clinical lymph node (cN) status (cN2 disease; P = .008). Moreover, no significant difference in survival was observed between patients with cN0/cN1 disease and patients with cN2 disease within the group (P = .4333).

CONCLUSIONS

Loss of control of cell-cycle checkpoints is a common occurrence in pN2 NSCLC. Functional cooperation between different cell-cycle regulators constitutes another level of regulation in cell growth control and tumor suppression. Preoperative patients with pN2 NSCLC, even those with cN2 disease, who have positive p21 and p16 protein expression in their primary tumors are expected to have a favorable postoperative prognosis and may be candidates for primary resection.

Immunohistochemical analysis of non-small cell lung cancer: correlation with clinical parameters and prognosis

Non-small cell lung cancers (NSCLC) vary in their biologic behavior. Recurrence and tumor-related mortality may be attributable to molecular abnormalities in primary tumors. This study evaluated such immunophenotypes with regard to cell cycle regulation and proliferation, apoptosis, and angiogenesis, to determine their significance for patient outcome. Core biopsies from 219 patients with NSCLC were assembled on tissue microarrays, and the expressions of p16, p21, p27, cyclin B1, cyclin E, Ki-67, caspase-3, survivin, bcl-2, VEGF, and endostatin were evaluated by immunohistochemistry. Despite previously described prognostic relevance of some of the investigated molecules, many of those markers were not directly associated with recurrence or survival. However, there was a trend for p16 immunoreactivity to be associated with a good prognosis (57% vs. 42% in 5-yr survival) (p=0.071). bcl-2 expression was strongly correlated with a better outcome (65% vs. 45% in 5-yr survival) (p=0.029), and the hazard of death for bcl-2 positive patients was 0.42 times of that for bcl-2 negative patients (p=0.047). A multivariate analysis with Cox proportional hazards model confirmed that the lymph node status (p=0.043) and stage (p=0.003) were other independent prognostic factors. Our results suggest that p16 and bcl-2 provide prognostic information independent of the TNM stage in NSCLC.

p21 as a prognostic factor in non-small cell lung carcinomas

Few studies have focused on the correlation between p21 expression and survival for patients with non-small cell lung carcinoma (NSCLC), and the results are not consistent. We investigated the expression of p21 in 90 cases of NSCLC to evaluate the correlation between the p21 expression level and the clinicopathologic characteristics with patient survival. p21 was expressed in the nuclei of all the NSCLCs. The percentage of immunoreactive cells varied from 1% to 70%. All the patients were subdivided into a high and a low p21 expression group on the basis of the median percentage (17.05). There was no significant correlation between the p21 expression level and age, gender, histologic type, histologic grade, or stage. Using uni- and multivariate analyses, survival was significantly associated with gender, stage, and the p21 expression level. The survival rate for the high p21 expression group was higher than that for the low p21 expression group in the entire patient group, and especially for stage II and III patients, males, adenocarcinomas, or p53-positive tumors. Our findings showed that high p21 expression was an independent prognostic factor for NSCLC. p21 may be useful for determining the candidates for adjuvant therapies and also for selecting the appropriate chemotherapeutic agents.

Immunohistochemical markers of prognosis in non-small cell lung cancer: a review and proposal for a multiphase approach to marker evaluation

Characteristics of the tumour that affect and predict the survival outcome of patients with cancer are prognostic markers for cancer. In non-small cell lung carcinoma (NSCLC), stage is the main determinant of prognosis and the basis for deciding options for treatment. Patients with early-stage tumour are treated by complete surgical resection, which is curative in 40-70% of patients. That there are other factors important in determining the biology of these tumours, especially genes that have a role in metastasis, is indicated. Such factors could potentially be used to further classify patients into groups according to substages that may be treated differently. During the past decade, a large number of proteins that are putatively important in carcinogenesis and cancer biology have been studied for their prognostic value in NSCLC, but none of them have been proved to be sufficiently useful in clinical diagnosis. Several markers (epidermal growth factor receptor, human epidermal growth factor receptor 2, Ki-67, p53 and Bcl-2) have been studied exhaustively. Ki-67, p53 and Bcl-2 are suggested to be important but weak prognostic markers, by meta-analyses of the results. Cyclin E, vascular endothelial growth factor A, p16(INK4A), p27(kip1) and beta-catenin are promising candidates, but require further study in large randomised clinical trial samples by using standardised assays and scoring systems. Some issues and inconsistencies in the reported studies to date are highlighted and discussed. A guideline for a multi-phase approach for conducting future studies on prognostic immunohistochemistry markers is proposed here.

Aberrant expression of BARD1 in breast and ovarian cancers with poor prognosis

Mutations in tumor-suppressor gene BARD1 have been found in inherited and spontaneous breast, ovarian and uterine cancers. BARD1 plays a critical role in DNA repair and ubiquitination as binding partner of BRCA1, with which it colocalizes to nuclear dots. Independently of BRCA1, BARD1 can induce p53-dependent apoptosis in response to genotoxic stress. Therefore, BARD1 or p53 might be defective in cancer cells spared from apoptosis. We investigated BARD1 and p53 expression in ovarian, breast and non-small-cell lung cancers. BARD1 expression was highly upregulated and cytoplasmic in most cancer cells, while weak nuclear staining was observed in the surrounding normal tissue. Maximal BARD1 expression was associated with the most malignant ovarian cancer, clear cell carcinoma. In breast cancer, BARD1 expression was correlated with poor differentiation and large tumor size, established factors of poor prognosis, as well as short disease-free survival. In contrast to breast and ovarian cancers, no correlation of BARD1 expression with either grade or stage could be determined for lung cancer. RT-PCR, performed on 10 ovarian cancers, revealed absence of the 5' portion of the BARD1 transcript in 7 tumors, and sequencing of the remaining 3 identified a missense mutation (A1291G) resulting in an amino acid change of glutamine 406 to arginine. These data suggest that genetic and epigenetic changes might lead to elevated cytoplasmic expression of BARD1 and that cytoplasmic BARD1 might be a poor prognostic factor for breast and ovarian cancers.

Immunohistochemical expression of p16(INK4a) is predictive of HR-HPV infection in cervical low-grade lesions

The p16(INK4a) is a cyclin-dependent kinase inhibitor that decelerates the cell cycle by inactivating the cyclin-dependent kinases involved in the phosphorylation of the retinoblastoma protein (RB). Expression of E6 and E7 oncogenes of high-risk (HR) human papillomavirus (HPV), affecting the RB-p16 pathway, leads to p16 upregulation. Although it is widely reported that p16 is overexpressed in a high percentage of preneoplastic lesions and in almost all carcinomas of the uterine cervix, protein upregulation and its correlation with HPV infection in low-grade lesions is still being debated. In this study, we investigated in parallel, p16 expression and HPV infection in 100 cervical biopsies (17 normal tissues, 54 CIN1, 10 CIN2, 11 CIN3, eight invasive squamous cancers). Results obtained demonstrated that none of the 17 normal cervical tissues, evaluated by immunohistochemistry, presented p16 positivity whereas, starting from CIN1 (31%) to CIN2 (90%), CIN3 (100%) and carcinomas (100%), a constant and significant increase of protein overexpression (P<0.0001) was observed. In addition, p16 overexpression consistently showed elevated sensitivity (84%) and specificity (98%) in detecting HR-HPV infection with a high positive predictive value (97%) and negative predictive value (86%). Of interest, 93% of the p16-positive CIN1 were also HR-HPV infected. Our findings confirmed that p16 overexpression is associated to high-grade precancerous lesions and cervical carcinomas, and further demonstrated that immunohistochemical evaluation of p16 may be a useful biomarker in identifying HR-HPV-infected low-grade lesions.

Molecular Profiling of Computed Tomography Screen-Detected Lung Nodules Shows Multiple Malignant Features

RATIONALE AND PURPOSE

Low-dose spiral computerized axial tomography (spiral CT) is effective for the detection of small early lung cancers. Although published data seem promising, there has been a significant degree of discussion concerning the potential of overdiagnosis in the context of spiral CT-based screening. The objective of the current study was to analyze the phenotypic and genetic alterations in the small pulmonary malignancies resected after detection in the University of Navarra/International Early Lung Cancer Action Project spiral CT screening trial and to determine whether their malignant molecular features are similar to those of resected lung tumors diagnosed conventionally.

EXPERIMENTAL DESIGN

We analyzed 17 biomarkers of lung epithelial malignancy in a series of 11 tumors resected at our institution during the last 4 years (1,004 high-risk individuals screened), using immunohistochemistry and fluorescence in situ hybridization (FISH). A parallel series of 11 gender-, stage-, and histology-matched lung cancers diagnosed by other means except screening was used as control.

RESULTS

The molecular alterations and the frequency of phenotypic or genetic aberrations were very similar when screen-detected and nonscreen-detected lung cancers were compared. Furthermore, most of the alterations found in the screen-detected cancers from this study were concordant with what has been described previously for stage I-II lung cancer.

CONCLUSIONS

Small early-stage lung cancers resected after detection in a spiral CT-based screening trial reveal malignant molecular features similar to those found in conventionally diagnosed lung cancers, suggesting that the screen-detected cancers are not overdiagnosed.

Role of cell-cycle regulators in lung cancer

Lung cancer is the leading cause of cancer death worldwide. Histologically, 80% of lung cancers are classified as non-small-cell lung cancer (NSCLC), and the remaining 20% as small-cell lung cancer (SCLC). Lung carcinoma is the result of molecular changes in the cell, resulting in the deregulation of pathways controlling normal cellular growth, differentiation, and apoptosis. This review summarizes some of the most recent findings about the role of cell-cycle proteins in lung cancer pathogenesis and progression.

COX-2 inhibitors suppress lung cancer cell growth by inducing p21 via COX-2 independent signals

COX-2 has been implicated in the control of human non-small cell lung carcinoma (NSCLC) cell growth. The mechanisms by which COX-2 exerts its mitogenic effects have not been entirely elucidated, but stimulation of prostaglandin E2 production and alterations in the expression of the cyclin-dependent kinase inhibitor p21(WAF-1/CIP1/MDA-6)(p2i) have been suggested. Here, we demonstrate that two COX-2 inhibitors (NS398 and Nimesulide) inhibit proliferation and induce apoptosis in NSCLC cells, and these effects were associated with induction of p21 mRNA and protein expression. However, the anti-growth effect of the COX-2 inhibitors and their ability to induce p21 were not affected by COX-2 siRNA suggesting that their actions were COX-2 independent. Instead, activation of the MEK-1/Erk pathway was necessary since COX-2 inhibitors stimulated the phosphorylation of ERKs, and their effects were blocked by PD98095, an inhibitor of this pathway. Furthermore, we show that both NS398 and Nimesulide induced p21 gene promoter activity and this was prevented by PD98095. COX-2 inhibitors increased nuclear protein binding to the Spl site in the promoter region of the p21 gene. Consistent with a role for p21, we found that p21 antisense oligonucleotides prevented the effects of COX-2 inhibitors on cell growth. In summary, our results suggest that COX-2 inhibitors suppress NSCLC cell growth by inducing the expression of the p21 gene through MEK-1/ERK signaling and DNA-protein interactions involving Spl. These observations unveil a mechanism for p21 gene regulation by COX-2 inhibitors in lung carcinoma cell growth and this pathway represents a potential target for therapy.

Long-term disease-free survival of patients with radically resected thymomas: relevance of cell-cycle protein expression

BACKGROUND

Despite radical surgical resection, thymomas often recur. The objective of the current retrospective study was to investigate the prognostic relevance of the expression of cell-cycle proteins in these neoplasms to formulate a possible therapeutic surveillance strategy for the prevention of recurrence.

METHODS

The authors retrospectively reviewed the main clinicopathologic factors, including the World Health Organization (WHO) classification, of patients with thymoma who had undergone radical surgical resection. Specimens were studied using immunohistochemistry and the expression of cell-cycle proteins (i.e., p21, p27, and p53) was assessed. Univariate and multivariate analysis of predicting survival prognostic factors were performed.

RESULTS

The authors analyzed 88 patients with thymoma who underwent radical surgical resection at the study institution. According to the Masaoka staging system, 41 patients had Stage I disease, 31 patients had Stage II disease, and 16 patients had Stage III disease. There were 24 tumor recurrences (27.3%), 4 of which were local, 16 of which were distant intrathoracic, and 4 of which were extrathoracic. The second radical resection provided a disease-free survival rate that was similar to the first. Only Masaoka stage (P = 0.001), WHO classification (P=0.001), high expression of p53 (P=0.03), and low expression of p21 (P=0.02) and p27 (P=0.001) were found to be correlated with a reduced disease-free survival. Low p27 expression was found to be the most significant predictive factor of a short disease-free survival (P=0.001), especially when associated with low p21 expression and high p53 expression (P=0.0001).

CONCLUSIONS

Long-term disease-free survival in thymoma patients treated with radical surgical resection was found to be correlated with Masaoka stage, WHO classification, and expression of cell-cycle proteins, with the latter found to be the most significant predictive factor. Functional cooperation between cell-cycle proteins might constitute another level of regulation in tumor growth. More careful surveillance should be adopted whenever there is negative cell-cycle protein expression.

Cell cycle related proteins as prognostic parameters in radically resected non-small cell lung cancer

BACKGROUND

Experimental evidence suggests that lung cancer development and progression can be linked to an increased proliferation rate.

AIMS/METHODS

To evaluate the immunohistochemical expression of seven components of the cell cycle machinery in a series of well characterised non-small cell lung cancer (NSCLC) specimens (n = 105).

RESULTS

Multivariate analysis revealed that simultaneous loss of expression of three of these factors--cyclin D1, the cyclin dependent kinase inhibitor p16, and the tumour suppressor retinoblastoma protein Rb2/p130--correlated with survival, confirming the hypothesis that the cyclin D1-p16-retinoblastoma tumour suppressor pathway is inactivated in most lung cancer samples.

CONCLUSIONS

These results suggest that loss of control of cell cycle checkpoints is a common occurrence in lung cancer and support the idea that functional cooperation between different cell cycle regulatory proteins constitutes another level of regulation in cell growth control and tumour suppression.

Prognostic implications of cell cycle, apoptosis, and angiogenesis biomarkers in non-small cell lung cancer: a review

Lung cancer is the leading cause of cancer death in the U.S. with survival restricted to a subset of those patients able to undergo surgical resection. However, even with surgery, recurrence rates range from 30% to 60%, depending on the pathologic stage. With the advent of partially effective, but potentially toxic adjuvant chemotherapy, it has become increasingly important to discover biomarkers that will identify those patients who have the highest likelihood of recurrence and who thus might benefit most from adjuvant chemotherapy. Hundreds of papers have appeared over the past several decades proposing a variety of molecular markers or proteins that may have prognostic significance in non-small cell lung cancer. This review analyzes the largest and most rigorous of these studies with the aim of compiling the most important prognostic markers in early stage non-small cell lung cancer. In this review, we focused on biomarkers primarily involved in one of three major pathways: cell cycle regulation, apoptosis, and angiogenesis. Although no single marker has yet been shown to be perfect in predicting patient outcome, a profile based on the best of these markers may prove useful in directing patient therapy. The markers with the strongest evidence as independent predictors of patient outcome include cyclin E, cyclin B1, p21, p27, p16, survivin, collagen XVIII, and vascular endothelial cell growth factor.

Surfactant Protein A Gene Deletion and Prognostics for Patients with Stage I Non–Small Cell Lung Cancer

PURPOSE

The present study was conducted to determine clinical relevance of surfactant protein A (SP-A) genetic aberrations in early-stage non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

To determine whether SP-A aberrations are lung cancer-specific and indicate smoking-related damage, tricolor fluorescence in situ hybridization with SP-A and PTEN probes was done on touch imprints from the lung tumors obtained prospectively from 28 patients with primary NSCLC. To further define the clinical relevance of SP-A aberrations, fluorescence in situ hybridization was done on both tumor cells and adjacent bronchial tissue cells from paraffin-embedded tissue blocks from 130 patients NSCLC for whom we had follow-up information.

RESULTS

SP-A was deleted from 89% of cancer tissues and the deletion was related to the smoking status of patients (P < 0.001). PTEN was deleted from 16% in the cancer tissues and the deletion was not related to the smoking status of patients (P > 0.05). In the cells isolated from paraffin-embedded tissue blocks, SP-A was deleted from 87% of the carcinoma tissues and 32% of the adjacent normal-appearing bronchial tissues. SP-A deletions in tumors and adjacent normal-appearing bronchial tissues were associated with increases in the risk of disease relapse (P = 0.0035 and P < 0.001, respectively). SP-A deletions in the bronchial epithelium were the strongest prognostic indicators of disease-specific survival (P = 0.025).

CONCLUSIONS

Deletions of the SP-A gene are specific genomic aberrations in bronchial epithelial cells adjacent to and within NSCLC, and are associated with tumor progression and a history of smoking. SP-A deletions might be a useful biomarker to identify poor prognoses in patients with NSCLC who might therefore benefit from adjuvant treatment.

Role of cdk4, p16INK4, and Rb expression in the prognosis of bronchioloalveolar carcinomas

BACKGROUND

The p16(INK4) protein has been identified as a potent inhibitor of cyclin-dependent kinase (cdk)4 by blocking cdk4-mediated phosphorylation of the tumor suppressor retinoblastoma (Rb) protein, thus allowing Rb-mediated growth suppression.

OBJECTIVES

Loss of p16(INK4) has been associated with a poor cancer prognosis, but its potential significance in bronchioloalveolar carcinomas (BACs) has not been explored.

METHODS

We examined immunohistochemical expression of p16(INK4), cdk4, and Rb proteins in 38 BACs and correlated their expression levels with known clinicopathological features of the disease.

RESULTS

All BACs expressed cdk4, while 89 and 82% expressed p16(INK4) and Rb proteins, respectively. None of the clinicopathological factors correlated with p16(INK4), cdk4, or Rb expression separately. A low p16(INK4)/cdk4 ratio was significantly associated with a high disease stage (p = 0.04), and the ratio tended to be lower in mucinous than nonmucinous tumors. BACs with a low p16(INK4)/cdk4 ratio showed significantly higher Rb expression levels (p = 0.02). Univariable survival analyses showed a significantly lower 5-year survival probability in patients with a high stage (p = 0.002) or low p16(INK4)/cdk4 ratio (p = 0.01).

CONCLUSIONS

The results suggest a role of the cdk4/p16(INK4) pathway in the prognosis of BACs. Further studies are warranted to clarify whether a low p16(INK4)/cdk4 ratio may identify tumors that are destined to behave unfavorably.

Absence of prognostic significance of p21(WAF1/CIP1) protein expression in non-small cell lung cancer

Prognostic value of p21WAF1/CIP1 expression in non-small-cell lung cancer patients (NSCLC) remains unclear. In this study the authors investigated the clinical significance of p21WAF1/CIP1 expression in a group of 117 NSCLC patients, who underwent curative pulmonary resection. Expression of p21WAF1/CIP1 protein was assessed immunohistochemically and samples showing>5% of positive tumor cells were considered positive. Seventy-six samples (65%) showed positive nuclear p21WAF1/CIP1 protein expression. There was no relationship between the expression of p21WAF1/CIP1 protein and major clinico-pathological factors, and neither there was an impact of p21WAF1/CIP1 protein expression on disease-free and overall survival. p21WAF1/CIP1 protein occurrence was not correlated with previously determined p53 protein expression and there was also no relationship between all possible p21WAF1/CIP1/p53 phenotypes and survival. In uni- and multivariate analysis only stage of disease was independent prognostic factors. These results suggest the lack of prognostic relevance of p21WAF1/CIP1 expression (analyzed separately or jointly with p53 protein) in surgically treated NSCLC patients.