Predictive value of expression of p16INK4A, retinoblastoma and p53 proteins for the prognosis of non-small-cell lung cancers

Molecular interaction studies of Deguelin and its derivatives with Cyclin D1 and Cyclin E in cancer cell signaling pathway: The computational approach

Deguelin is a major active ingredient and principal component in several plants and it is a potential molecule to target proteins of cancer cell signaling pathway. As a complex natural extract, deguelin interacts with various molecular targets to exert its anti-tumor properties at nanomolar level. It induces cell apoptosis by blocking anti-apoptotic pathways, while inhibiting tumor cell multiplication and malignant transformation through p27-cyclin-E-pRb-E2F1- cell cycle control and HIF-1alphaVEGF antiangiogenic pathways. In silico studies of deguelin and its derivatives is performed to explore interactions with Cyclin D1 and Cyclin E to understand the molecular insights of derivatives with the receptors. Deguelin and its derivatives are minimized by Avogadro to achieve stable conformation. All docking simulation are performed with AutoDockVina and virtual screening of docked ligands are carried out based on binding energy and number of hydrogen bonds. Molecular dynamics (MD) and Simulation of Cyclin D1 and Cyclin E1 is performed for 100 ns and stable conformation is obtained at 78 ns and 19 ns respectively. Ligands thus obtained from docking studies may be probable target to inhibit cancer cell signaling pathways.

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.

Prognostic role of Rb, p16, Cyclin D1 proteins in soft tissue sarcomas

PURPOSE

The aim of this study was to determine the expressions of Rb, p16, and cyclin D1 in soft tissue sarcomas, and we also wanted to identify the prognostic factors according to the clinicalpathologic features.

MATERIALS AND METHODS

We reviewed the charts and radiographic films of 66 sarcoma patients. Tissue samples were collected from these patients. Immunochemistry was performed using formalin-fixed, paraffin-embedded tissue samples to examine the expressions of p16, Rb, and cyclin D1 proteins.

RESULTS

The median duration of overall survival was 47.8 months (range, 20.0 to 70.7 months) and the 5 years survival rate was 39%. As for the correlation between the degree of immunohistochemical staining for Rb protein and the histological tumor grades, there was a significant difference with a p-value of 0.019. However, no significant correlation was shown for p16 and cyclin D1. The overall survival duration of the Rb negative group (staining cell <20%) and the heterogeneous group (cell staining 20 to 80%) was 53.5±6.6 months and the overall survival duration of the Rb homogeneous group was 18.3±6.4 months, and there was a significant difference with a p-value of 0.016. However, no significant difference was shown between the survival rate according to the p16 and cyclin D1 expressions. On the multivariate analysis that was done with Rb, p16, the tumor size, grade and site, and patient age, the Rb gene expression was the most significant independent prognostic factor with a risk ratio of 3.01 (p=0.04).

CONCLUSION

The expression of Rb protein was correlated with the histologic grade and overall survival of patients with soft tissue sarcomas.

p16INK4A inactivation mechanisms in non-small-cell lung cancer patients occupationally exposed to asbestos

Epidemiological studies have shown that asbestos fibers constitute the major occupational risk factor and that asbestos acts synergistically with tobacco smoking to induce lung cancer. Although some somatic gene alterations in lung cancer have been linked to tobacco smoke, few data are available on the role of asbestos fibers. P16/CDKN2A is an important tumor suppressor gene that is frequently altered in lung cancer via promoter 5'-CpG island hypermethylation and homozygous deletion, and rarely via point mutation. Many studies suggest that tobacco smoking produces P16/CDKN2A promoter hypermethylation in lung cancer, but the status of this gene in relation to asbestos exposure has yet to be determined. The purpose of this study was to investigate the mechanism of P16/CDKN2A alterations in lung cancer in asbestos-exposed patients. P16/CDKN2A gene status was studied in 75 human non-small-cell lung cancer (NSCLC) cases with well-defined smoking habits, and detailed assessment of asbestos exposure, based on occupational questionnaire and determination of asbestos bodies in lung tissue. The results of this study confirm published data on the effect of tobacco smoke on P16/CDKN2A gene alterations, characterized by significantly higher P16/CDKN2A promoter hypermethylation in heavy smokers (more than 40 pack-years (P-Y)) than in smokers of less than 40 P-Y. These results also demonstrate a higher incidence of loss of heterozygosity and homozygous deletion in asbestos-exposed cases, after adjustment for age and cumulative tobacco consumption, than in unexposed cases (P=0.0062). This study suggests that P16/CDKN2A gene inactivation in asbestos-exposed NSCLC cases mainly occurs via deletion, a feature also found in malignant mesothelioma, a tumor independent of tobacco smoking but associated with asbestos exposure, suggesting a possible relationship with an effect of asbestos fibers.

Role of DMP1 and its future in lung cancer diagnostics

Lung cancer is the most lethal carcinoma worldwide. Mutations of p53, inactivation of p16(INK4a), and overexpression of cyclins E, A and B are independently associated with poor prognoses of patients, while the prognostic value of cyclin D1 or RB expression is inconclusive. Cyclin D binding myb-like protein 1 (Dmp1) encodes a DNA binding protein that receives signals from oncogenic Ras and functions as a tumor suppressor by activating the Arf-p53 [corrected] pathway. Dmp1 has been shown to be haplo-insufficient for tumor suppression in mouse models including K-ras-mediated lung carcinogenesis. The human DMP1 gene is located on chromosome 7q21, and our recent results revealed that the hDMP1 gene is deleted, but not mutated or silenced, in approximately 40 % of human non-small-cell lung carcinomas. These cases typically retained wild-type ARF and p53 and expressed very low levels of the hDMP1 protein. Thus, hDMP1 loss could be a novel diagnostic marker for non-small-cell lung carcinomas.

Immunophenotypic profiling of nonsmall cell lung cancer progression using the tissue microarray approach

This study, using tissue microarrays, aimed at the immunomorphologic profiling of nonsmall cell lung cancer (NSCLC) cases to reveal clinically relevant disease groups and biomarkers associated with patients' survival and tumor progression including brain metastatic potential. Donor tissue blocks were form 59 patients, including 33 primary tumors without distant metastasis and 26 brain metastatic primary tumors as well as the brain metastases. Sections were immunostained for 29 markers targeting molecules of cell adhesion, cell growth, cell cycle, and apoptosis regulation. beta-Catenin expression was the only independent prognostic marker associated with better outcome. Elevated expression of collagen XVII, CD44v6, and caspase-9, and the reduced production of beta-catenin and cellular apoptosis susceptibility protein were significantly associated with the metastatic potential of primary NSCLC. Expression of positive cell cycle regulators cyclin D1 and cyclin D3 was also increased in metastatic primary tumors. Metastatic tumor progression into the brain was accompanied by prominent p16, syndecan-1, p53 (DO7), and caspase-3 protein levels. Hierarchical clustering of complex immunoprofiles based on the differentially expressed markers grouped NSCLCs of the poorest outcome with high correlation including 2/3 of brain metastases of mixed histology. The brain metastatic potential of NSCLCs may be linked to the elevated levels of cyclinD1, cyclinD3, p16, p53, caspase-3, caspase-9, CD44v6, and collagen XVII and the down-regulation of beta-catenin and cellular apoptosis susceptibility protein. Unsupervised immunoprofiles based on differentially expressed biomarkers may help selecting lung cancers with aggressive behavior.

Homozygous deletion of p16INK4a and tobacco carcinogen exposure in nonsmall cell lung cancer

Inactivation of p16(INK4a) in the Rb pathway is among the most common somatic alterations observed in nonsmall cell lung cancers (NSCLCs). While epigenetic inactivation of the p16(INK4a) gene promoter has been shown to be associated with increased tobacco carcinogen exposure, little investigation of any similar association of homozygous deletion or mutation of p16(INK4a) and tobacco use has been completed. In 177 consecutive NSCLCs, we examined the determinants of p16(INK4a) homozygous deletion and mutation, including the pattern of tobacco smoking and asbestos exposure. We observed that p16(INK4a) homozygous deletion occurred at a higher frequency in never smokers as compared to former and current smokers (p = 0.01). This observation suggested that tumors from these patients might be more prone to DNA deletion events; consistent with this, epigenetic silencing of the DNA double-strand break repair genes FancF and BRCA1 was also associated with homozygous deletion of p16(INK4a)(p = 0.002 and p = 0.06, respectively). Finally, mutation of p16(INK4a) was rare and only occurred in patients who were smokers. Hence, the character of somatic alteration in the Rb pathway (deletion, mutation or methylation silencing) in NSCLC is associated with the pattern of tobacco exposure, suggesting that susceptibility to lung cancer is, at least in part, mediated by the biological mechanism that selects for the character of the induced somatic lesion.

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.

RB family members as predictive and prognostic factors in human cancer

The retinoblastoma family members--pRb, pRb2/p130 and p107--are tumor suppressor genes involved in controlling four major cellular processes: growth arrest, apoptosis, differentiation and angiogenesis. Molecular genetic studies have identified abnormalities of these tumor suppressor genes in a large proportion of human cancers. These genetic alterations have emerged as significant factors in the pathogenesis and progression of many types of tumors and are therefore likely to provide relevant information to assess risk in cancer patients. There is a pressing clinical need to identify prognostic and predictive factors for patients with cancer, because there is an undeniable importance in being able to determine which patients will have a favorable outcome without further therapy (prognostic factor) and which will need some additional treatment (predictive factor). This review examines the predictive and/or prognostic role of each retinoblastoma family member in human cancer.

Lung Cancer Pathogenesis Associated With Wood Smoke Exposure

BACKGROUND

Tobacco is considered the most important cause of lung cancer, but other factors could also be involved in its pathogenesis. The aim of the present work was to establish an association between wood smoke exposure and lung cancer pathogenesis, and to analyze the effects of wood smoke on p53 and murine double minute 2 (MDM2) protein expression.

DESIGN

Blood samples were obtained from 62 lung cancer patients, 9 COPD patients, and 9 control subjects. Of the 62 lung cancer patients, 23 were tobacco smokers (lung cancer associated with tobacco [LCT] group), 24 were exposed to wood smoke (lung cancer associated with wood smoke [LCW] group), and 15 could not be included in these groups. Western blot assays were performed to identify the presence of p53, phospho-p53, and murine double minute 2 (MDM2) isoforms in plasma samples. Densitometric analysis was used to determine the intensity of p53, phospho-p53, and MDM2 bands.

RESULTS

Approximately 38.7% of the lung cancer patients examined had an association with wood smoke exposure, most of them women living in rural areas. Adenocarcinoma was present in 46.7% of these patients. The p53 and phospho-p53 proteins were significantly increased in LCW samples (56,536.8 +/- 4,629 densitometry units [DU] and 58,244.8 +/- 7,492 DU, respectively [+/- SD]), in comparison with the other groups. The 57-kD MDM2 isoform plasma concentration was very high in LCW and LCT samples (75,696.4 +/- 11,979 DU and 78,551.7 +/- 11,548 DU, respectively). MDM2-p53 complexes were present in a high concentration in control and COPD subjects. This allows p53 degradation and explains the low concentrations of p53 found in these groups. MDM2-phospho-p53 complexes were observed in COPD but not in the other samples. This correlates with the low concentration of p53 observed in the COPD group (13,657 +/- 2,012 DU), and could explain the different clinic evolution of this smoker population in comparison with the LCT subjects.

CONCLUSION

This study suggests that there is a possible association of lung cancer with wood smoke exposure. Likewise, our findings demonstrate that wood smoke could produce similar effects on p53, phospho-p53, and MDM2 protein expression as tobacco.

Overexpression of the aldo-keto reductase family protein AKR1B10 is highly correlated with smokers' non-small cell lung carcinomas

PURPOSE

Squamous cell carcinoma (SCC) and adenocarcinoma of the lung are currently subject to similar treatment regimens despite distinct differences in histology and epidemiology. The aim of this study is to identify a molecular target with diagnostic and therapeutic values for SCC.

EXPERIMENTAL DESIGN

Genes specifically up-regulated in SCC were explored through microarray analysis of 5 SCCs, 5 adenocarcinomas, 10 small cell lung carcinomas, 27 normal tissues, and 40 cancer cell lines. Clinical usefulness of these genes was subsequently examined mainly by immunohistochemical analysis.

RESULTS

Seven genes, including aldo-keto reductase family 1, member B10 (AKR1B10), were identified as SCC-specific genes. AKR1B10 was further examined by immunohistochemical analysis of 101 non-small cell lung carcinomas (NSCLC) and its overexpression was observed in 27 of 32 (84.4%) SCCs and 19 of 65 (29.2%) adenocarcinomas. Multiple regression analysis showed that smoking was an independent variable responsible for AKR1B10 overexpression in NSCLCs (P < 0.01) and adenocarcinomas (P < 0.01). AKR1B10 staining was occasionally observed even in squamous metaplasia, a precancerous lesion of SCC.

CONCLUSION

AKR1B10 was overexpressed in most cases with SCC, which is closely associated with smoking, and many adenocarcinoma cases of smokers. These results suggest that AKR1B10 is a potential diagnostic marker specific to smokers' NSCLCs and might be involved in tobacco-related carcinogenesis.

Prognostic Implications of Molecular and Immunohistochemical Profiles of the Rb and p53 Cell Cycle Regulatory Pathways in Primary Non–Small Cell Lung Carcinoma

Purpose: Many studies have highlighted the aberrant expression and prognostic significance of individual proteins in either the Rb (particularly cyclin D1, p16INK4A, and pRb) or the p53 (p53 and p21Waf1) pathways in non–small cell lung cancer. We hypothesize that cumulative abnormalities within each and between these pathways would have significant prognostic potential regarding survival.

Experimental Design: Our study population consisted of 106 consecutive surgically resected cases of predominantly early-stage non–small cell lung cancer from the National Cancer Institute-Mayo Clinic series, and assessment of proteins involved both immunohistochemical (cyclin D1, p21Waf1, pRb, p16INK4A, and p53) and mutational analysis (p53) in relationship to staging and survival.

Results: Cyclin D1 overexpression was noted in 48% of the tumors, p16INK4A negative in 53%, pRb negative in 17%, p53 immunopositive in 50%, p53 mutation frequency in 48%, and p21Waf1 overexpression in 47%, none with prognostic significance. Cyclin D1 overexpression in pRb-negative tumors revealed a significantly worse prognosis with a mean survival of 2.3 years (P = 0.004). A simultaneous p53 mutation dramatically reduced the mean survival time to 0.9 years (P = 0.007). Cyclin D1 overexpression with either a p53 mutation or a p53 overexpression was also associated with a significantly poorer prognosis (P = 0.0033 and 0.0063, respectively).

Conclusions: Some cumulative abnormalities in the Rb and p53 pathways (e.g., cyclin D1 overexpression and p53 mutations) significantly cooperate to predict a poor prognosis; however, the complexity of the cell cycle protein interaction in any given tumor warrants caution in interpreting survival results when specific protein abnormalities are taken in isolation.

Prognostic relevance of altered pRb and p53 protein expression in surgically treated non-small cell lung cancer patients

OBJECTIVE

The prognostic value of pRb and p53 altered expression in non-small cell lung cancer (NSCLC) remains debatable. We assessed the occurrence of altered pRb and p53 protein expression, and the prognostic value of these assays considered as separate and combined variables in operable NSCLC. The study group included 195 NSCLC consecutive patients from one institution who underwent curative pulmonary resection between 1994 and 1999.

METHODS

Expression of pRb and p53 was assessed immunohistochemically with the use of monoclonal antibodies (LM95.1 and Pab 1801, Oncogene Science, respectively).

RESULTS

A lack of pRb and abnormal p53 protein expression were found in 57 (29%) and 92 samples (47%), respectively, whereas both abnormalities (pRb-/p53+) occurred in 24 samples (12%). There was no relationship between altered pRb/p53 expression and major clinico-pathological characteristics, neither was there a significant difference in disease-free and overall survival between particular groups of patients with tumors carrying four possible pRb/p53 phenotypes. In uni- and multivariate analysis, the only variable associated with shortened disease-free and overall survival was stage of disease (p < 0.001) and degree of tumor differentiation (p = 0.005).

CONCLUSION

These results suggest that altered pRb and p53 expression does not provide prognostic information in operable NSCLC patients.

Loss of p16 expression is of prognostic significance in locally advanced prostate cancer: an analysis from the Radiation Therapy Oncology Group protocol 86-10

PURPOSE

The retinoblastoma (RB) cell cycle regulatory pathway is known to be deregulated in virtually all known human tumors. The protein product of the RB gene, pRB, and its upstream regulator, p16, are among the most commonly affected members of this pathway. We investigated the prognostic significance of both pRB and p16 expression in locally advanced prostate cancers, from patients treated on the Radiation Therapy Oncology Group (RTOG) protocol 86-10.

MATERIALS AND METHODS

Sixty-seven cases from RTOG 86-10 had immunohistochemically stained slides, judged interpretable for both p16 and pRB, available for analysis. Median follow-up was 8.9 years (range, 6.0 to 11.8 years) for surviving patients. Staining for each marker was then correlated with overall survival, local progression, distant metastasis, and disease-specific survival.

RESULTS

Loss of p16 expression, as defined by expression was significantly associated with reduced overall survival (P =.039), disease-specific survival (P =.006), and higher risk of local progression (P =.0007) and distant metastasis (P =.026) in the univariate analysis. In the multivariate analysis, loss of p16 was significantly associated with reduced disease-specific survival (P =.0078) and increased risk of local failure (P =.0035) and distant metastasis (P =.026). A borderline association with reduced overall survival (P =.07) was also evident. Loss of pRB was associated with improved disease-specific survival on univariate (P =.028) and multivariate analysis (P =.043), but carried no other significant outcome associations.

CONCLUSION

Loss of p16 is significantly associated with adverse clinical outcome in cases of locally advanced prostate cancer.

Clinical significance of P16INK4A and retinoblastoma proteins in non-small-cell lung carcinoma

This study was performed to determine the frequency of expression loss of p16 and pRb; their relations with each other, tumour histology, tumour stage, nodal status, and survival in formalin fixed, paraffin embedded tumour tissues of patients with non-small-cell lung carcinoma (NSCLC). P16 and/or pRb expression loss is observed in 72 (75.8%) out of 95 patients, and 70 (73.7%) of them showed inverse correlation (P<0.05). Thirty-six (37.9%) of the p16 positive cases usually showed weak or moderate immunohistochemical staining. Loss of p16 expression was found to be significantly greater in squamous cell carcinoma than in adenocarcinoma cases, whilst no relation was observed with other clinical parameters. Immunohistochemical reactivity for pRb was generally moderate or strong. PRb expression loss was observed in 15.8% of the cases, and no relation was found between pRb loss and age, sex, tumour histology, tumour stage, or nodal status. PRb negative squamous cell carcinoma cases had significantly shorter survival independent of nodal status. These results suggest that disruption of p16/pRb pathway is frequently involved in NSCLC, and pRb expression loss in cases with squamous cell carcinoma may predict clinical outcome.

Blood vessel invasion in resected non small cell lung carcinomas is predictive of metastatic occurrence

Prognosis of patients with non small cell lung cancer (NSCLC) remains difficult to assess, even after adjustment for pathological stage. Prognostic value of numerous biological markers has been evaluated, with conflicting results. Data of 86 patients with NSCLC treated by surgery were collected with clinical characteristics, histopathological data including tumor differentiation and status of blood and lymphatic vessel invasion and evaluation by immunohistochemistry of Rb, Bcl-2 and Ki-67 expression. Prognostic values for overall survival (OS) and event-free survival (EFS) were analyzed by the log tank test and the multivariable Cox model. Using univariable analyses, pT, pN, poor differentiation or large cell subtype were associated with a poor OS, while lymphatic and/or blood vessel invasion were associated with a short EFS. None of the molecular markers had a significant prognostic value for either outcome. In multivariable analyses, only stage remained of prognostic value for OS. Interestingly, the presence of blood vascular invasion in the tumor was significantly predictive for subsequent metastatic occurrence in stages I and II. This feature might, therefore, be relevant for administration of adjuvant therapy in completely resected NSCLC.

Prognostic factors in non-small cell lung cancer: a decade of progress

STUDY OBJECTIVES

To provide a systematic overview of the literature investigating patient and tumor factors that are predictive of survival for patients with non-small cell lung cancer (NSCLC), and to analyze patterns in the design of these studies in order to highlight problematic aspects of their design and to advocate for appropriate directions of future studies.

DESIGN

A systematic search of the MEDLINE database and a synthesis of the identified literature.

MEASUREMENTS AND RESULTS

The database search (January 1990 to July 2001) was carried out combining the MeSH terms prognosis and carcinoma, nonsmall cell lung. Eight hundred eighty-seven articles met the search criteria. These studies identified 169 prognostic factors relating either to the tumor or the host. One hundred seventy-six studies reported multivariate analyses. Concerning 153 studies reporting a multivariate analysis of prognostic factors in patients with early-stage NSCLC, the median number of patients enrolled per study was 120 (range, 31 to 1,281 patients). The median number of factors reported to be significant in univariate analyses was 4 (range, 2 to 14 factors). The median number of factors reported to be significant in multivariate analyses per study was 2 (range, 0 to 6 factors). The median number of studies examining each prognostic factor was 1 (range, 1 to 105 studies). Only 6% of studies addressed clinical outcomes other than patient survival.

CONCLUSIONS

While the breadth of prognostic factors studied in the literature is extensive, the scope of factors evaluated in individual studies is inappropriately narrow. Individual studies are typically statistically underpowered and are remarkably heterogeneous with regard to their conclusions. Larger studies with clinically relevant modeling are required to address the usefulness of newly available prognostic factors in defining the management of patients with NSCLC.

Alterations of the p16(ink4a) gene in resected nonsmall cell lung tumors and exfoliated cells within sputum

Recently, we reported that p16 protein expression was nondetectable in 49.5% of 107 resected nonsmall cell lung cancers (NSCLCs), suggesting that the p16(INK4a) gene is frequently inactivated in primary NSCLC. To identify the molecular basis for this p16 immunohistochemical negativity further, we performed a genetic and epigenetic study of p16(INK4a) status in a series of 115 NSCLC samples parallel to the clinicopathologic and prognostic analyses. Microdissected tumor DNA samples were screened for homozygous deletion using comparative multiplex-polymerase chain reaction (PCR), for intragenic mutation using direct sequencing and for loss of heterozygosity (LOH) using an intragenic microsatellite marker, D9S942. Of these samples, 67 were further analyzed by SmaI-based PCR methylation assay to evaluate aberrant methylation at the gene. To examine the correlation of aberrant methylation in tumor and sputum samples, sputum samples from 12 matched patients were assessed for this change. We found that methylation of the p16(INK4a) gene was present in 38 of the 67 (56.7%) tumors and was significantly associated with negative p16 protein expression (p = 0.029). A 92% (11/12) concordance of sputum samples with matched resected tumors was found. The survival rates among adenocarcinoma patients with p16(INK4a) methylation were lower, but at a level of borderline significance compared with those patients without methylation (p = 0.071). In addition, 29.4% of the informative cases were found to harbor LOH at D9S942. None of the 115 microdissected tumors exhibited homozygous deletion in the p16(INK4a) gene. Only 1 patient exhibited a complex mutation at the fourth ankyrin repeat consensus sequence and concordantly demonstrated p16 immunohistochemical negativity. Overall, 69% (79/115) of NSCLC tumors had at least 1 type of p16(INK4a) alteration. Our data provide compelling evidence that p16(INK4a) alterations are involved in NSCLC tumorigenesis and that promoter methylation is the predominant mechanism in p16(INK4a) deregulation.

Increased expression of beta-catenin predicts better prognosis in nonsmall cell lung carcinomas

BACKGROUND

beta-Catenin has been shown to function as a Wnt signaling molecule to stimulate cyclin D1 expression and cell growth in several kinds of tumors.

METHODS

The authors immunohistochemically examined specimens of 217 surgically resected primary nonsmall cell lung carcinomas (NSCLCs) for beta-catenin expression and classified them semiquantitatively into three categories, including those with high, moderate, and low scores of expression.

RESULTS

High, moderate, and low scores of expression were found in 37 (17.1%), 145 (66.8%), and 35 (16.1%) tumors, respectively. beta-Catenin expression was not correlated with cyclin D1 expression, but was positively correlated with the Ki-67 cell growth fraction (P = 0.04). The direct sequencing analysis for the beta-catenin gene mutation of 13 specimens of 217 tumors for the current study revealed no mutations. The relation between survival and beta-catenin expression was evaluated in 148 potentially curatively resected tumors with pathologic Stages I-IIIA. A trend toward better survival was found in patients with tumors having higher scores. In multivariate analysis, high beta-catenin expression was a significant and independent favorable prognostic factor (hazards ratio, 0.31; P = 0.007) as was pathologic stage. Analyzed by cell type, in nonsquamous cell carcinomas, patients with tumors having high scores survived a significantly longer time than those with tumors having moderate or low scores (5-year survival rates, 84%, 55%, and 32%, respectively; P = 0.02), and high beta-catenin expression tended to be a favorable prognostic factor (hazards ratio, 0.32; P = 0.052).

CONCLUSIONS

These results indicate that, in NSCLCs, increased expression of beta-catenin can predict favorable prognosis of patients with resected tumors, suggesting that accumulation of beta-catenin has no or little oncogenic effect via activation of the Wnt pathway, unlike in colon carcinomas or hepatomas.

Tumor p16M is a possible marker of advanced stage in non-small cell lung cancer

BACKGROUND AND OBJECTIVES

The inactivation of the tumor suppressor gene p16 by methylation (p16M) has been recognized recently as an important process in the oncogenesis for a variety of carcinomas. There have been few reports of its use in lung cancer. We investigate p16M in patients with non-small cell lung cancer (NSCLC).

METHODS

p16M in tumor, plasma, and pleural lavage fluid from patients with resectable NSCLC were investigated by using methylation-specific polymerase chain reaction.

RESULTS

Of the 33 patients studied, 14 (42%) had p16M tumors. There was a significant association between p16M tumors and advanced TNM staging (stage III or IV, P=0.047, Fisher exact test). Circulating p16M was identified in 2 of the 14 patients with p16M tumor and was also associated with advanced TNM staging (P=0.049). The presence of plasma p16M in NSCLC patients and in p16M tumor patients was associated with poor survival and shorter disease-free survival (P=0.0028, P=0.0039, Kaplan-Meier log rank). In addition, p16M was present in three preresectional and four postresectional lavage samples. Preresectional p16M was associated with poor survival and shorter disease-free survival (P=0.0085). p16M tumor involving the visceral pleura was significantly associated with positive p16M postresectional lavage.

CONCLUSIONS

Positive tumor and plasma p16M indicate advanced staging in NSCLC. Patients with plasma and preresection pleural lavage p16M have shorter survival. Further research in this direction is warranted.

Role of apoptosis in the response of lung carcinomas to anti-cancer treatment

Resistance of tumor cells to treatment often accounts for the failure of traditional forms of anti-cancer therapy. It is well known that tumors from the same histological group and stage of development are highly heterogeneous in their sensitivity to therapy. Among the factors that can influence tumor sensitivity are DNA repair capacity, distribution of cells throughout the cell cycle, proliferation potential, etc. In many cases, anti-cancer therapy eliminates tumor cells via apoptosis, an active form of cell death characterized by cell shrinkage and the removal of cells in a neat, orderly fashion. However, this process is not always efficient. In the present review, the precise role that apoptosis plays in the response of lung carcinomas to chemotherapy and radiation treatment is discussed.

Loss of p16 and/or pRb protein expression in NSCLC. An immunohistochemical and prognostic study

The disruption of p16/pRb pathway has been reported in several types of human cancer including lung cancer. However, the etiological and prognostic involvement of this pathway remains poorly defined in lung tumorigenesis in Taiwan. Therefore, we investigated the expressions of p16 and pRb in 107 non-small cell lung cancer (NSCLC) patients by immunohistochemical analysis. The associations of altered p16 and pRb expressions with prognosis were also examined. Sixty-four specimens (59.8%) exhibited alteration of p16 and/or pRb expression, with 49.5 and 22.4% of the tumors failing to express p16 and pRb, respectively. However, there was no reciprocally correlated expression of p16 and pRb. Negative p16 and pRb expression did not correlate well with patients' clinicopathological parameters such as age, sex, smoking habit, tumor type, and tumor stage. In addition, negative p16 and pRb expression was not statistically associated with poor prognosis (P=0.10 and P=0.74, respectively). Our results suggested that the disruption of the p16/pRb pathway plays a significant role in NSCLC tumorigenesis whereas it may not have significant importance in the prognostic evaluation of NSCLC in Taiwan.