Sequential loss of heterozygosity in the progression of squamous cell carcinoma of the lung

Characterization of circulating tumor cells by fluorescence in situ hybridization

Tumor cells in blood of patients with metastatic carcinomas have been associated with poor survival prospects. Further characterization of these cells may provide further insights into the metastatic process. Circulating Tumor Cells (CTC) were enumerated in 7.5 mL of blood with the CellSearch system. After enumeration of Cytokeratin+, CD45-, nucleated cells, the cells are fixed in the cartridge while maintaining their original position. Cartridges were hybridized with FISH probes against the centromeric regions of chromosome 1, 7, 8, and 17. Next fluorescence images of the FISH probes of the previous identified CTC were acquired. Leukocytes surrounding the CTC were used as internal controls. The number of copies of chromosome 1, 7, 8, and 17 could be determined in 118 CTC containing blood samples from 59 metastatic prostate cancer patients. The samples contained a total of 21,751 CTC (mean 184, median 16, SD 650). Chromosome counts were obtained in 61% of the relocated CTC. On an average, these CTC contained 2.8 copies of chromosome 1, 2.7 copies of chromosome 7, 3.1 copies of chromosome 8, and 2.3 copies of chromosome 17. CTC in which no chromosome count was obtained most likely underwent apoptosis indicated by the expression of M30. In 6/59 patients only diploid CTC were detected these samples, however, only contained 1-5 CTC. Heterogeneity in the chromosomal abnormalities was observed between CTC of different patients as well as among CTC of the same patient. Cytogenetic composition of CTC can be reliably assessed after they have been identified by the CellSearch system. The majority of CTC in hormone refractory prostate cancer are aneuploid confirming that they indeed are cancer cells. An extensive heterogeneity in the copy number of each of the chromosomes was observed.

Clonal divergence in lung cancer development is associated with allelic loss on chromosome 4

Patients who receive curative treatment for lung cancer can develop additional lung tumors that may or may not be related to the original tumor and thus require different clinical management. If a subsequent tumor has a pattern of allele loss, revealed by allelotype analysis, overlapping that of the first tumor, it is believed to be a local recurrence or metastasis. In this case history, we present loss of heterozygosity analyses of the original primary tumor, and two second primary tumors occurring in the ipsilateral and the contra-lateral lungs. The allelotyping suggests that these tumors are all clonally related but concordance is not complete. Our interpretation is that the original primary tumor and the two new primary tumors have developed to full malignancy independently, but are clonally related, possibly via a clone of motile progenitor cells. Deletion mapping of DNA from biopsies of this patient delineated a region in 4p16 that we had previously shown to be lost in the transition from carcinoma in situ to invasive tumor. We identified a minimally deleted region encompassing six genes including two candidate tumor suppressor genes, CRMP1 a lung cancer metastasis-suppressing gene and PPP2R2C a gene for a regulatory subunit of the PP2 complex known to suppress tumorigenesis, particularly viral induced transformation.

3p microsatellite signature in exhaled breath condensate and tumor tissue of patients with lung cancer

RATIONALE

Our group has recently demonstrated the possibility of studying microsatellite alterations (MAs) of 3p in the DNA of exhaled breath condensate (EBC) of patients with non-small cell lung cancer (NSCLC).

OBJECTIVES

To verify whether MAs analyzed in DNA from EBC reflect a profile of alterations present in tumor tissue of NSCLC.

METHODS

Fifty-nine subjects undergoing histologic diagnosis for clinical suspicion of lung cancer entered the study: 41 were found to have NSCLC and 18 to have nonneoplastic diseases. All subjects underwent allelotyping on DNA from whole blood, EBC, and lung tissue removed for histologic diagnosis by analyzing a panel of five microsatellites located in chromosomal region 3p. Results obtained from DNA of the three biological sites and nonneoplastic tissues from controls were compared.

MEASUREMENTS AND MAIN RESULTS

MAs in DNA from tumor tissues and EBC of each patient with cancer presented an overlapping profile of loss of heterozygosity and microsatellite instability. An MA profile of DNA of lung tissue reflecting the DNA of EBC profile from controls was also confirmed. Smoking status was associated with the presence of MAs in patients with NSCLC and in control subjects.

CONCLUSIONS

We demonstrated that MAs in DNA from EBC of patients with NSCLC are significantly more frequent than in control subjects. More interesting, the MA profile of DNA from EBC corresponds to that from lung cancer tissue of each patient with NSCLC.

Dissimilarity in gene expression profiles of lung adenocarcinoma in Japanese men and women

BACKGROUND

Although clinical differences in lung cancer between men and women have been noted, few studies have examined the sex dissimilarity using gene expression analysis.

OBJECTIVE

The purpose of this study was to determine the different molecular carcinogenic mechanisms involved in lung cancers in Japanese men and women.

METHODS

Patients who received surgery for stage I lung adenocarcinoma were included. RNA was extracted from cancerous and normal tissue, and gene expression was then examined with oligonucleotide microarray analysis. A quantitative polymerase chain reaction assay was performed.

RESULTS

In a microarray analysis of tissue from 13 men and 6 women, 12 genes were under-expressed and 24 genes were overexpressed in lung adenocarcinoma in women compared with men. Genes related to cell cycle were present in underexpressed genes, and genes related to apoptosis, ubiquitination, and metabolism were observed in overexpressed genes. Of interest among the selected genes were WAP four-disulfide core domain 2 (WFDC2) and major histocompatibility complex, class II, DM alpha (HLA-DMA); these genes were classified into 2 groups by hierarchical clustering analysis. Expression of WFDC2 in nonsmokers was significantly higher than that in smokers (P=0.023). However, there was no significant difference in HLA-DMA expression between smokers and nonsmokers.

CONCLUSION

Thirty-six genes that characterize lung adenocarcinoma by sex were selected. This information may contribute to the development of novel diagnostic techniques and treatment modalities that consider sex differences in lung adenocarcinoma.

3p microsatellite alterations in exhaled breath condensate from patients with non-small cell lung cancer

The still-high mortality for lung cancer urgently requires the availability of new, noninvasive diagnostic tools for use in early diagnosis and screening programs. Recently, exhaled breath condensate (EBC) has been proposed as a useful tool to obtain biological information on lung cancer disease. This study provides, for the first time, evidence that DNA alterations already described in lung cancer are detectable in EBC from patients with non-small cell lung cancer (NSCLC) and in healthy subjects. Thirty patients with histologic evidence of NSCLC and 20 healthy subjects were enrolled in the present study. All subjects had allelotyping analysis of DNA from EBC (EBC-DNA) and from whole blood (WB-DNA) of a selected panel of five microsatellites (D3S2338, D3S1266, D3S1300, D3S1304, D3S1289) located in chromosomal region 3p. Results from healthy subjects and subjects with cancer, and from EBC and WB, were compared. In addition, the relationships with smoking habit and clinicopathologic tumor features were considered. Microsatellite alterations (MAs) were found in 53% of EBC-DNA and in 10% of WB-DNA loci investigated in patients with NSCLC (p < 10(-6)); conversely, MAs were present only in 13% of EBC-DNA and in 2% of WB-DNA informative loci in healthy subjects. In patients with NSCLC, a direct association between number of MAs detected in EBC-DNA and tobacco consumption was observed. We conclude that EBC-DNA is highly sensitive in detecting MA information unique to patients with lung cancer. Furthermore, MA information seems to be directly related with tobacco consumption, and is potentially applicable to screening and early diagnostic programs for patients with NSCLC.

p53 and FHIT mutations and microsatellite alterations in malignancy-associated pleural effusion

Cancer is a genetic disease and thus is influenced by oncogenes and tumor suppressor genes. To determine whether the genetic analysis of pleural fluid can be used to diagnose malignant effusion, we investigated p53 and FHIT mutations and microsatellite alterations (MA) in the pleural fluid of 40 patients with pleural effusion associated with malignancy (ME) and in the pleural fluid of 17 patients with tuberculous pleurisy (TB) as a control group. p53 mutations were detected in five ME patients (13%) and in no TB patient, and FHIT mutations were detected in seven ME patients (18%) and two TB patients (12%). For four microsatellite markers, D3S1234, D3S1285, D9S171, and TP53, in ME patients, loss of heterozygosity (LOH) was seen in 10 (25%), 5 (13%), 10 (25%), and 6 patients (15%), respectively, and microsatellite instability (MI) in 6 (15%), 0 (0%), 1 (3%), and 3 patients (8%), respectively. Using the same markers, in TB patients, LOH was seen in three (18%), one (6%), three (18%), and one (6%), respectively, and MI in one (6%), zero (0%), zero (0%), and zero (0%), respectively. Twenty-five ME cases (63%) exhibited MA (LOH or MI) in at least one marker. Moreover, in four (80%) of five ME cases with negative cytology and no carcinoembryonic antigen increase in pleural fluid, MAs were identified. In ME, positive cytology was found in 42.5%, and positive MA, using four markers, in 63%. Although still limited in terms of sensitivity and specificity, this study shows that molecular diagnostic strategies could enhance the diagnostic yield in cases of malignant effusion.

Plasma DNA microsatellite panel as sensitive and tumor-specific marker in lung cancer patients

The majority of lung cancer patients have tumor-derived genetic alterations in circulating plasma DNA that could be exploited as a diagnostic tool. We used fluorescent microsatellite analysis to detect alterations in plasma and tumor DNA in 34 patients who underwent bronchoscopy for lung cancer, including 11 small cell lung cancer (SCLC) and 23 nonsmall cell lung cancer (NSCLC) (12 adenocarcinomas, 11 squamous cell carcinomas) and 20 controls. Allelotyping was performed with a selected panel of 12 microsatellites from 9 chromosomal regions 3p21, 3p24, 5q, 9p, 9q, 13q, 17p, 17q and 20q. Plasma DNA allelic imbalance (AI) was found in 88% (30 of 34 patients), with a similar sensitivity in SCLC and NSCLC. In the 24 paired available tumor tissues, 83% (20 of 24) presented at least 1 AI. Among these patients, 85% (17 of 20) presented also at least 1 AI in paired plasma DNA, but the location of the allelic alterations in paired plasma and tumor DNA could differ, suggesting the presence of heterogeneous tumor clones. None of the 20 controls displayed plasma or bronchial DNA alteration. A reduced panel of six markers (at 3p, 5q, 9p, 9q) showed a sensitivity of 85%. Moreover, a different panel of microsatellites at 3p and 17p13 in SCLC and at 5q, 9p, 9q and 20q in NSCLC patients could be specifically used. Analysis of plasma DNA using this targeted panel could be a valuable noninvasive test and a useful tool to monitor disease progression without assessing the tumor.

Genetic heterogeneity in lung and colorectal carcinoma as revealed by microsatellite analysis in plasma or tumor tissue DNA

BACKGROUND

Determination of tumor clonality has implications for molecular characterization and the optimal treatment of cancer. Allelotyping allows detection of the two alleles, maternal and paternal, and provides additional information regarding clonal genetic defects. The presence of allelic imbalances (AI) in tumors is a general event, but is not necessary at the same allele (alternative AI). The authors' goal was to determine whether the presence of alternative AI (AA) was a marker of heterogeneity and prognosis.

METHODS

To further analyze the heterogeneity of lung tumors, tumor DNA released in the plasma was compared with primary tumor DNA from 24 lung carcinoma patients. The comparison was performed by allelotyping using 12 microsatellites targeting 9 chromosomal regions, taking in each case leukocyte DNA as reference. To extend and confirm these observations, 26 primary colorectal carcinomas with paired synchronous liver metastasis were analyzed using an enlarged panel of 33 microsatellites.

RESULTS

AA were observed in 40% (20 of 50) of all patients, in 25% (6 of 24) of lung carcinoma patients but at a higher level, and in 54% (14 of 26) of colorectal carcinoma patients. They affected different chromosome localizations and each tumor stage. In both types of cancer, patients with AA had a higher AI mean frequency in their primary tumor.

CONCLUSIONS

Detection of AA is an original marker of heterogeneous tumors, demonstrating that independent events occurred on specific genetic sites required for cancer progression.

Preneoplastic lesions of the lung

Lung cancer is the leading cause of cancer deaths worldwide. If we can define and detect preneoplastic lesions, we might have a chance of improving survival. The World Health Organization has defined three preneoplastic lesions of the bronchial epithelium: squamous dysplasia/carcinoma in situ; atypical adenomatous hyperplasia; and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. These lesions are believed to progress to squamous cell carcinoma, adenocarcinoma and carcinoid tumors, respectively. In this review we summarize the data supporting the preneoplastic nature of these lesions, and delve into some of the genetic changes found in atypical adenomatous hyperplasia and squamous dysplasia/carcinoma in situ.

Expression of early lung cancer detection marker: hnRNP-A2/B1 and its relation to microsatellite alteration in non-small cell lung cancer

We have reported that a mouse monoclonal antibody, 703D4, which recognizes heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP-A2/B1) can frequently detect lung cancer in exfoliated sputum epithelial cells 1-2 years earlier than routine chest X-ray or sputum cytomorphology. We along with others have shown that microsatellite alteration (MA) at selected loci can be recognized in sputum cells prior to clinical lung cancer. The present study was undertaken to determine how frequently the expression of hnRNP-A2/B1 message is associated with neoplastic clonal expansion as shown by MA in 41 cases of non-small cell lung cancer (NSCLC). We used Northern blotting to evaluate hnRNP-A2/B1 mRNA expression in lung tumor and remote noninvolved lung. We evaluated microsatellite instability (i.e. shifts; MI) or loss of heterozygosity (LOH) with a panel of 13 microsatellite markers at loci identified previously as susceptible in NSCLC. Of the 41 tumors, 25 (61%) over-expressed hnRNP-A2/B1 and 33 (80%) demonstrated MA in at least one of 13 loci (58% in at least two loci). The association between MA (one locus) and the overexpression of hnRNP-A2/B1 is statistically significant (P=0.0082), and those lung tumors with MA at two or more loci were significantly more likely to over-express hnRNP-A2/B1 mRNA (P=0.004). MA of loci on 3p were the only MA statistically associated with hnRNP-A2/B1 message overexpression (P=0.001). We conclude that lung tumor cells undergoing clonal expansion frequently upregulate hnRNP-A2/B1.

3p21, 5q21, and 9p21 allelic deletions are frequently found in normal bronchial cells adjacent to non-small-cell lung cancer, while they are unusual in patients with no evidence of malignancy

Molecular cytogenetic and loss of heterozygosity (LOH) analyses of non-small-cell lung cancer (NSCLC) have shown frequent allelic deletions in a variety of chromosomes, such as 1p, 3p, 5q, 8p, 9p, 11p, 11q, and 17p. Allelic loss at 3p21, 9p21, and 5q21 has also been reported in premalignant epithelial lesions of the bronchus and in normal bronchial cells. These findings suggest that a tissue field of somatic genetic alterations precedes the histopathological phenotypic changes of carcinoma. LOH at chromosomal regions 3p21, 5q21, 9p21, and 17p (TP53) was looked for in the peritumoural normal bronchial cells from 30 archival surgically resected tumours. Microdissected normal bronchial cells from 20 benign cytological smears were also added to the study. Matched populations of lymphocytes, tumour cells, and normal bronchial cells adjacent to the tumour were microdissected from paraffin-embedded tissues, while matched populations of normal bronchial cells and inflammatory cells were microdissected from benign cytological smears (bronchial brushings). Polymerase chain reaction (PCR) amplification was performed utilizing the specific markers D5S346, D3S1300, D9S157, D9S171, and TP53. Within the NSCLC tumour cells, LOH was more frequently found at the 5q21 locus (72% of the informative cases), the 3p21 locus (47%), 9p21 (48%), and 17p (33%). Within the peritumoural normal bronchial cells, LOH at 5q21 was found in 37.5% of the cases, 22% showed LOH at 3p21, 27% at 9p21, and 13% at 17p (TP53). LOH was also detected in one case, in normal bronchial cells obtained from cytological smears at one locus (5q21). In conclusion, normal bronchial mucosa adjacent to NSCLC has frequent allelic losses at 3p21, 5q21, and 9p21, while LOH at these loci is unusual in normal bronchial cells obtained from cytological smears from patients with no evidence of malignancy. LOH at these loci may be present before the onset of the malignant growth. LOH studies may supplement the histopathological evaluation of bronchial cells to detect genotypic alterations in both cytological and biopsy specimens.

Pulmonary preinvasive neoplasia

Advances in molecular biology have increased our knowledge of the biology of preneoplastic lesions in the human lung. The recently published WHO lung tumour classification defines three separate lesions that are regarded as preinvasive neoplasia. These are (1) squamous dysplasia and carcinoma in situ (SD/CIS), (2) atypical adenomatous hyperplasia (AAH), and (3) diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIP-NECH). SD/CIS is graded in four stages (mild, moderate, severe, and CIS), based upon the distribution of atypical cells and mitotic figures. Most airways showing SD/CIS demonstrate a range of grades; many epithelia are hard to assess and the reproducibility of this complex system remains to be established. Detailed criteria are, however, welcome and provide an objective framework on which to compare various molecular changes. Alterations in gene expression and chromosome structure known to be associated with malignant transformation can be demonstrated in CIS, less so in dysplasias, but also in morphologically normal epithelium. The changes might be sequential, and their frequency and number increase with atypia. Less is known of the "risk of progression" of SD/CIS to invasive "central" bronchial carcinoma. It may take between one and 10 years for invasion to occur, yet the lesion(s) may be reversible if carcinogen exposure ceases. AAH may be an important precursor lesion for peripheral "parenchymal" adenocarcinoma of the lung: the "adenoma" in an adenoma-carcinoma sequence. There is good morphological evidence that AAH may progress from low to high grade to bronchioloalveolar carcinoma (BAC; a non-invasive lesion by definition). Invasion then develops within BAC and peripheral lung adenocarcinoma evolves. The molecular events associated with this progression are not well understood and studies are hampered by a lack of clear criteria to distinguish high grade AAH from BAC. Nonetheless, as with SD/CIS, the patterns of expression of tumour associated genes are consistent with neoplastic progression. We have little idea of the incidence of AAH in the normal or "smoking" populations. It is found more frequently in cancer bearing lungs, especially in those with adenocarcinoma, and is more common in women. No data are available on the risk of progression of AAH. DIPNECH is an exceptionally rare lesion associated with the development of multiple carcinoid tumours. Almost nothing is known of its biology. Knowledge of these lesions will be crucial in the design and understanding of lung cancer screening programmes, where it is likely that the morphological and, more importantly perhaps, the molecular characteristics of these lesions will provide useful targets for detection and possibly even treatment.

Telomerase activity significantly correlates with chromosome alterations, cell differentiation, and proliferation in lung adenocarcinomas

Telomerase activity was examined by the telomeric repeat amplification protocol assay in 25 cases of lung adenocarcinoma, in relation to cancer cell differentiation, proliferation, and chromosome alterations. Telomerase activity, chromosome alterations, and cell proliferation assessed by Ki-67 labeling were significantly lower (P < .001 to .05) in well-differentiated (10 cases) than in moderately differentiated (8 cases) or poorly differentiated (7 cases) lesions. Telomerase activity by semiquantitative analysis with scoring of 0 to 3 was significantly correlated with similarly graded chromosome alterations (P < .05) and Ki-67 labeling indices (P < .002). Telomerase activity and chromosome alteration (T-C) indices generated by multiplication of telomerase activity and chromosome alteration scores also showed a significant correlation with cell differentiation. The Clara cell subtype, confirmed by electron microscopic analysis, significantly predominated in the well-differentiated group, showing a low grade of telomerase activity and chromosome alterations and low Ki-67 labeling indices, suggesting clinical relevance. No significant association of telomerase activity was found with p53 protein accumulation or Bcl-2 protein expression. The good correlation of telomerase activity with chromosome alterations, cell differentiation, and Ki-67 labeling indices suggests that this parameter might have potential application in estimation of prognosis.

Fine mapping of PPH1, a gene for familial primary pulmonary hypertension, to a 3-cM region on chromosome 2q33

Familial primary pulmonary hypertension (PPH) is a rare autosomal dominant disease characterized by distinctive changes in pulmonary arterioles that lead to increased pulmonary artery pressures, right ventricular failure, and death. Our previous studies had mapped the disease locus, PPH1, to a 27-cM region on chromosome 2q31-q33, with a maximum multipoint logarithm of the odds favoring genetic linkage score of 3.87 with markers D2S350 and D2S364. To narrow the minimal genetic region for PPH, we physically mapped 33 highly polymorphic microsatellite markers and used them to genotype 44 affected individuals and 133 unaffected individuals from 17 families with PPH. We observed recombination events that substantially reduced the interval for PPH1 to the approximately 3-cM region that separates D2S311 and D2S1384. This entire region lies within chromosome 2q33. A maximum two-point lod score of 7.23 at a recombination fraction of zero was obtained for marker D2S307. A maximum multipoint lod score of 7.41 was observed close to marker D2S1367. The current minimal genetic region contains multiple candidate genes for PPH, including a locus thought to play a role in lung cancer.

Loss of heterozygosity in human skin

Loss of heterozygosity (LOH) is a genetic mechanism by which a heterozygous somatic cell becomes either homozygous or hemizygous because the corresponding wild-type allele is lost. LOH has today been recognized as a major cause of malignant growth. This article gives a comprehensive review of skin disorders in which an origin from LOH has been either documented at the molecular level or postulated on the basis of clinical evidence. LOH has been shown to cause basal cell carcinoma, squamous cell carcinoma, and malignant melanoma, but this mechanism can likewise be taken as an important model to explain the origin of many other skin diseases such as benign hamartomas; type 2 segmental manifestation of autosomal dominant skin disorders; a pronounced segmental manifestation of acquired skin disorders with a polygenic background, superimposed on symmetric lesions of the usual type; paired mutant patches in the form of either allelic or nonallelic twin spotting; and the exceptional familial occurrence of some nevi, reflecting paradominant transmission. completion of this learning activity, readers should be familiar with the mechanism of LOH and its general significance for the biology of plants, animals, and humans. Participants should understand that this mechanism plays a crucial role not only in cutaneous malignant growth but also in the development of benign skin disorders, and they should be able to examine such diseases with a prepared mind to gain a better understanding of their origin.

Molecular genetic characteristics of lung cancer--useful as real' tumor markers?

The increased knowledge about the molecular mechanisms leading to the development of a tumor has opened new horizons for basic and applied research. Lung cancer is among the tumor entities with the highest incidence and mortality rates. Recently new drugs and therapeutic options for patients with lung cancer were developed. These developments demand new and improved techniques for the sensitive and specific detection of lung tumor cells. Some of the molecular genetic features of lung tumor cells are summarized and the possibilities to use these characteristics as new tumor markers are discussed.