Genetic events in the pathogenesis of lung cancer

Detection of FHIT and p16 mRNA deletion in biopsy specimens obtained by bronchoscopy for the diagnosis of lung cancer

The purpose of this study was to investigate the diagnostic value of the deletion of fragile histidine triad (FHIT) and p16INK4a (p16) mRNA in biopsies obtained by bronchoscopy. Biopsies were analyzed using RT-PCR in 52 patients with lung cancer and 19 patients with benign lung disease. The results showed that the detection rates of FHIT and p16 gene transcript deletion were significantly higher in lung cancer patients than in patients with benign lung disease (65.4% versus 10.5%, p=0.001 and 59.6% versus 5.3%, p<0.001, respectively). The sensitivities for detecting FHIT and p16 transcript deletion in biopsies were 65.4% and 59.6% (combined 80.8%), respectively, which were markedly better than those of histology and cytology (42.3% and 34.6%, respectively; combined 57.7%). In 22 lung cancer patients with negative histology and cytology at initial bronchoscopy, FHIT and p16 mRNA loss was detected in 40.9% (9/22) and 36.4% (8/22) cases, respectively. FHIT mRNA loss was associated with smoking status in lung cancer patients. In conclusion, deletion of FHIT and p16 mRNA can be identified in biopsies obtained during bronchoscopic procedures. FHIT and p16 mRNA deletion can be used as biomarkers in the clinical diagnosis of lung cancer and may serve as adjuncts to histology and cytology in lung cancer diagnosis.

Molecular diagnosis and prognostic significance of lymph node micrometastasis in patients with histologically node-negative non-small cell lung cancer

Lymph node metastasis is a major prognostic factor in resected non-small cell lung cancer (NSCLC). However, 30-40 % rate of recurrence after performing complete resection in node-negative patients suggests that their nodal staging is suboptimal. We aimed to evaluate the molecular diagnosis and prognostic significance of lymph node micrometastasis in patients with node-negative NSCLC. Primary tumor samples from 62 patients with resected stage I-IIB NSCLC were screened for fragile histidine triad (FHIT) and CDKN2A mRNA deletion using reverse transcriptase polymerase chain reaction (RT-PCR). The molecular alternations were found in tumors of 49 patients. A total of 269 lymph nodes from these 49 NSCLC patients with FHIT or/and CDKN2A deletion tumors were examined. Fifteen positive-control nodes and ten negative-control nodes were also analyzed for FHIT and CDKN2A mRNA deletion. Thirty-nine (22 %) and 22 (18 %) lymph nodes from the 49 patients with FHIT and CDKN2A mRNA deletion in primary tumor had FHIT and CDKN2A mRNA deletion, respectively. The types of FHIT and CDKN2A mRNA deletion in lymph nodes were identical with those in their primary tumors. By combination of two markers, 16 patients (32.7 %) were found to have nodal micrometastasis. Survival analysis showed that patients with nodal micrometastasis had reduced disease-free survival (P = 0.001) and overall survival (P = 0.002) rates. Multivariate analysis demonstrated that nodal micrometastasis was an independent predictor for worse prognosis. Thus, the detection of lymph node micrometastasis by FHIT and CDKN2A mRNA deletion RT-PCR will be helpful to predict the recurrence and prognosis of patients with completely resected stage I-IIB NSCLC.

Beneficial influence of capsaicin on lipid peroxidation, membrane-bound enzymes and glycoprotein profile during experimental lung carcinogenesis

This study was designed to examine the impact of a principal component of hot red peppers and chilli peppers, capsaicin, on alterations in lipid peroxidation, membrane-bound enzyme profiles and glycoprotein levels during benzo(a)pyrene (BP)-induced lung cancer in Swiss albino mice. BP (50 mgkg−1) induced deleterious changes that were revealed by alterations in lipid peroxidation, membrane-bound enzyme (Na+/K+ATPase, Ca2+ATPase and Mg2+ATPase) activity, levels of total protein and protein-bound carbohydrate components (sialic acid, hexose, hexosamine, hexuronic acid and fucose). Pre-co-treatment with capsaicin (10 mgkg−1) restored the detrimental effects induced by BP, indicating its protective role in BP-induced lung cancer.

Amelioration of benzo (a) pyrene-induced lung carcinogenesis in strain A mice by diphenylmethyl selenocyanate

Organoselenocyanates are an important class of chemopreventive agents, which possess antioxidative, antimutagenic and anticarcinogenic properties. In the present study, we used benzo (a) pyrene (BP)-induced lung carcinogenesis model for assessment of the chemopreventive efficacy of diphenylmethyl selenocyanate, a synthetic organoselenocyanate. BP was given at a dose of 0.2mg/mouse to initiate lung carcinogenesis in strain A mouse and the Se compound was given orally at a dose of 3mg/kgb.w. Histopathological characterizations and biochemical estimation were done to determine the protective effect of Se compound during the progression of lung carcinogenesis. Hyperplasia and severe dysplasia, the precancerous stage, were evident in carcinogen control group after 8th and 22nd week, respectively. These times were selected as the targets for chemoprevention. Treatment with the Se compound effectively reduced the incidence of hyperplasia and severe dysplasia. The Se compound also significantly (p<0.01) reduced microsomal lipid peroxidation and induced glutathione-S-transferase activity in liver and lung when measured after 8th and 22nd week. Lung cancer is diagnosed in majority of cases only at a later stage. These findings will further strengthen the view on organoselenocyanate as an effective cancer chemopreventive agent against lung carcinogenesis when applied at the post-initiation phase.

Loss of Fragile Histidine Triad Gene Expression in Advanced Lung Cancer Is Consequent to Allelic Loss at 3p14 Locus and Promoter Methylation

The fragile histidine triad (FHIT) gene located at the 3p14.2 locus plays an important role in the pathogenesis of lung cancer. The objective of this study was to analyze loss of heterozygosity and FHIT gene methylation status and correlate them to fhit expression. Bronchoscopically obtained lung biopsies from 30 cases of histologically proven carcinoma of the lung in stage III were assessed for the alterations in the FHIT gene. Fhit protein expression was determined by immunohistochemistry, and transcript levels were determined by reverse transcription-PCR. Microsattelite alterations and methylation status of the Fhit gene promoter was determined by PCR. Loss of heterozygosity at the 3p14 locus was observed in all the 30 cases at least by one of the three microsatellite polymorphic markers. The FHIT gene promoter showed complete methylation in 37% cases and partial methylation in 47% cases, and 16% cases showed no promoter methylation. FHIT full-length coding region (exons 5-9) transcripts were present in eight cases (26.6%), and aberrant transcripts were additionally seen in four cases. Loss of FHIT mRNA expression correlated to FHIT promoter methylation but not to loss of heterozygosity at the 3p14 locus. There was a strong correlation between the expression of FHIT at the transcript and protein level. The apoptotic index estimated by the terminal deoxynucleotidyl transferase-mediated nick end labeling assay was significantly correlated to the fhit protein expression. The results of this study indicate that in locally advanced carcinoma of the lung, there is frequent loss of FHIT expression, and methylation of the FHIT gene promoter is an important mechanism of its inactivation.

Lung cancer and related risk factors: an update of the literature

At the present time, lung cancer is the leading cause of cancer-related death in males. Diagnostic difficulty makes detection complicated and this, in conjunction with the low survival rate, renders the disease a serious health problem. In-depth knowledge of associated risk factors is therefore called for, in order to prevent or at least reduce the appearance of lung cancer and to open new avenues of research. Although the disease has a multicausal aetiology, tobacco accounts for 85-90% of all cases. This paper reviews the current situation, dividing the risk factors, for study purposes, into two groups; intrinsic (non-modifiable) and extrinsic (modifiable).

Chromosome aberrations as a predictor of clinical outcome for smoking associated lung cancer

The ability to identify individuals at greatest risk of developing lung cancer can significantly enhance the efficacy of intervention modalities. One strategy for identifying these individuals is through biomarkers that reflect the severity of their cancer. In the present study, we evaluated 22 lung cancer patients and 35 controls to determine whether the frequency of chromosome aberrations was significantly associated with specific clinical variables such as the histological type, grade and stage of the tumors. Chromosome aberrations (expressed as total breaks) were investigated on chromosome 1 in interphase nuclei obtained from blood lymphocytes of the study participants using the fluorescence in situ hybridization (FISH) chromosome aberration assay. Our results indicate a significant linear increase (P=0.01) in the level of breaks with respect to the grade of the carcinoma. The poorly differentiated tumors had a significantly higher level of chromosome breaks mean+/-SD (1.7+/-0.46) as compared to the well differentiated tumors (0.98+/-0.23, P<0.05). These results indicate that chromosome aberrations, as determined by the FISH assay, can be used as a biomarker for identifying individuals with aggressive types of lung cancer and potentially, as a predictor for prognostic outcome of the disease.

Biology of lung cancer

OBJECTIVES

To provide a review of the biology of lung tumor development and progression, and advances in gene and antimetastatic therapies.

DATA SOURCES

Review articles, research studies, and book chapters pertaining to the biology of lung cancer.

CONCLUSION

Advances in understanding the molecular basis of lung cancer initiation, promotion, and progression will provide more effective methods of early detection and treatment of this disease. Promising new treatment methods based on tumor biology include gene therapies, antibodies against growth factors, and agents that prevent angiogenesis and tissue invasion.

IMPLICATIONS FOR NURSING PRACTICE

An understanding of the biology of cancer assists nurses with the development of protocols for the assessment and monitoring of patients receiving treatments based on cancer biology. Oncology nurses will assume important counseling roles with the development of genetic testing and prognostic markers.

Mirror-image tumors in mirror-image twins

Genetic factors are known to play a role in causing lung cancer. Twin cases of bronchioloalveolar, squamous, and anaplastic bronchogenic carcinoma have been previously reported. We describe mirror-image twins with adenocarcinoma of the lung occurring in mirror-image locations. They shared smoking and an occupational risk, carpentry, in addition to identical genetic backgrounds.

Loss of heterozygosity on chromosome arm 17p in small cell lung carcinomas, but not in neurofibromas, in a patient with von Recklinghausen neurofibromatosis

BACKGROUND

It has been suggested that the genetic abnormality responsible for von Recklinghausen neurofibromatosis (NF1) increases a patient's risk of various kinds of malignancies. The incidence of small cell lung carcinoma (SCLC) as a complication of NF1, however, is rare. To clarify the relationship between NF1 and SCLC, possible loss of heterozygosity of chromosome 17 in a patient with SCLC combined with NF1 was analyzed.

METHODS

Possible loss of heterozygosity for chromosome 17 was analyzed by a molecular genetic approach using several chromosome 17-specific polymorphic DNA markers.

RESULTS

In both primary tumor and metastatic tumors of SCLC, loss of heterozygosity was detected on chromosome arm 17p, but not on 17q. Loss of heterozygosity, however, was detected on neither 17p nor 17q in neurofibromas and normal tissue.

CONCLUSIONS

The formation of SCLC may result from several genetic alterations, including inactivation of tumor-suppressor gene on chromosome 17p, most likely P53, although it still is unknown whether or not a mutation of the NF1 gene on 17q was involved in the development of SCLC in this patient.

Distinct hypermethylation patterns occur at altered chromosome loci in human lung and colon cancer

Regional increases in DNA methylation occur in normally unmethylated cytosine-rich areas in neoplastic cells. These changes could potentially alter chromatin structure to inactivate gene transcription or generate DNA instability. We now show that, in human lung and colon cancer DNA, hypermethylation of such a region consistently occurs on chromosome 17p in an area that is frequently reduced to homozygosity in both tumor types. Over the progression stages of colon neoplasia, this methylation change increases in extent and precedes the allelic losses on 17p that are characteristic of colon carcinomas. We also show on chromosome 3p that regional hypermethylation may nonrandomly accompany chromosome changes in human neoplasia. Increased methylation is consistent in small-cell lung carcinoma DNA at two 3p loci that are constantly reduced to homozygosity in this tumor, but it is not seen in colon cancer DNA, in which these loci are infrequently structurally altered.

Expression of epidermal growth factor receptor in plutonium-239-induced lung neoplasms in dogs

The expression of epidermal growth factor receptor (EGF-R) was examined in canine lung tumors and in proliferative epithelial foci induced by plutonium-239 to determine if EGF-R was associated with specific neoplastic phenotypes or putative preneoplastic lesions. Seventeen (47%) of 36 canine lung tumors expressed EGF-R. Of these 17 tumors, three tumors hybridized with an erb-B RNA probe, which identified activated cell oncogenes. The expression of EGF-R was not correlated with tumor etiology, e.g., spontaneous versus radiation induced, but did correlate with specific histologic phenotypes. Nineteen (15%) of 127 proliferative epithelial foci in the canine lungs also expressed EGF-R. The phenotypic specificity demonstrated for EGF-R in canine lung tumors parallels that previously shown in human lung tumors. This finding, in addition to the identification of EGF-R in nonneoplastic proliferative lung lesions, indicates that radiation-induced lung tumors in the dog may be a useful animal model to investigate the role of EGF-R in lung carcinogenesis.

Screening for lung cancer. Is it worthwhile?

Prevention of lung cancer remains the best method of decreasing lung cancer mortality. Patients who smoke should be urged to quit, and children, teenagers, and young adults must not begin smoking. At high risk are smokers, especially those under 40 years of age who may have smoked two to four packs of cigarettes per day for 20 years; persons who have had a previous lung cancer; patients with bullous emphysema; patients with asbestosis; and patients with evidence of chronic airflow obstruction. Although radiographic screening may detect lung cancer earlier and lead to increased 5-year survival rates, it does not reduce lung cancer mortality rates.