Allelic loss on the short arm of chromosome 11 in non-small-cell lung cancer

Evaluation of Potential Mechanisms Controlling the Catalase Expression in Breast Cancer Cells

Development of cancer cell resistance against prooxidant drugs limits its potential clinical use. MCF-7 breast cancer cells chronically exposed to ascorbate/menadione became resistant (Resox cells) by increasing mainly catalase activity. Since catalase appears as an anticancer target, the elucidation of mechanisms regulating its expression is an important issue. In MCF-7 and Resox cells, karyotype analysis showed that chromosome 11 is not altered compared to healthy mammary epithelial cells. The genomic gain of catalase locus observed in MCF-7 and Resox cells cannot explain the differential catalase expression. Since ROS cause DNA lesions, the activation of DNA damage signaling pathways may influence catalase expression. However, none of the related proteins (i.e., p53, ChK) was activated in Resox cells compared to MCF-7. The c-abl kinase may lead to catalase protein degradation via posttranslational modifications, but neither ubiquitination nor phosphorylation of catalase was detected after catalase immunoprecipitation. Catalase mRNA levels did not decrease after actinomycin D treatment in both cell lines. DNMT inhibitor (5-aza-2′-deoxycytidine) increased catalase protein level in MCF-7 and its resistance to prooxidant drugs. In line with our previous report, chromatin remodeling appears as the main regulator of catalase expression in breast cancer after chronic exposure to an oxidative stress.

Catalase, a remarkable enzyme: targeting the oldest antioxidant enzyme to find a new cancer treatment approach

This review is centered on the antioxidant enzyme catalase and will present different aspects of this particular protein. Among them: historical discovery, biological functions, types of catalases and recent data with regard to molecular mechanisms regulating its expression. The main goal is to understand the biological consequences of chronic exposure of cells to hydrogen peroxide leading to cellular adaptation. Such issues are of the utmost importance with potential therapeutic extrapolation for various pathologies. Catalase is a key enzyme in the metabolism of H2O2 and reactive nitrogen species, and its expression and localization is markedly altered in tumors. The molecular mechanisms regulating the expression of catalase, the oldest known and first discovered antioxidant enzyme, are not completely elucidated. As cancer cells are characterized by an increased production of reactive oxygen species (ROS) and a rather altered expression of antioxidant enzymes, these characteristics represent an advantage in terms of cell proliferation. Meanwhile, they render cancer cells particularly sensitive to an oxidant insult. In this context, targeting the redox status of cancer cells by modulating catalase expression is emerging as a novel approach to potentiate chemotherapy.

Regulation of catalase expression in healthy and cancerous cells

Catalase is an important antioxidant enzyme that dismutates hydrogen peroxide into water and molecular oxygen. The catalase gene has all the characteristics of a housekeeping gene (no TATA box, no initiator element sequence, high GC content in promoter) and a core promoter that is highly conserved among species. We demonstrate in this review that within this core promoter, the presence of DNA binding sites for transcription factors, such as NF-Y and Sp1, plays an essential role in the positive regulation of catalase expression. Additional transcription factors, such as FoxO3a, are also involved in this regulatory process. There is strong evidence that the protein Akt/PKB in the PI3K signaling pathway plays a major role in the expression of catalase by modulating the activity of FoxO3a. Over the past decade, other transcription factors (PPARγ, Oct-1, etc.), as well as genetic, epigenetic, and posttranscriptional processes, have emerged as crucial contributors to the regulation of catalase expression. Altered expression levels of catalase have been reported in cancer tissues compared to their normal counterparts. Deciphering the molecular mechanisms that regulate catalase expression could, therefore, be of crucial importance for the future development of pro-oxidant cancer chemotherapy.

The Ets transcription factor ELF5 functions as a tumor suppressor in the kidney

Renal cell carcinoma is an important clinical disease with poorly understood etiology. ELF5 is an epithelial-specific member of the Ets family of transcription factors, characterized by the 80 amino acid Ets domain that binds the purine-rich GGAA/T Ets motif found in the promoter regions of a variety of genes. Since ELF5 is highly expressed in kidney and has been postulated to function as a tumor suppressor, at least in the context of the breast, we investigated its role in kidney cancer. In renal cell carcinoma ELF5 expression was consistently decreased in tumor samples versus normal. ELF5 mRNA was decreased in 94% of lesions tested and ELF5 protein was undetectable in 40/40 kidney-derived carcinomas. Re-expression of the ELF5 gene in 786-O renal carcinoma cells suppressed their tumorigenic capacity in vitro and in vivo. This work is the first to suggest that ELF5 has tumor suppressor activity in the kidney.

Overexpression of tumor susceptibility gene TSG101 in human papillary thyroid carcinomas

Functional inactivation of tumor susceptibility gene tsg101 leads to cellular transformation and tumorigenesis in mice. While human TSG101 is located in a region where frequent loss of heterozygosity can be detected in a variety of cancers, no genomic deletion in TSG101 gene has been reported, casting a doubt on the role of TSG101 as a classical tumor suppressor. Some studies have revealed that TSG101 is a frequent target of splicing defects, which correlate with cellular stress and p53 status. Furthermore, recent reports have identified TSG101 as a part of the MDM2/p53 regulatory circuitry, a well-recognized circuitry that upon deregulation results in tumorigenesis. Interestingly, overexpression of tsg101 from an adventitious promoter also leads to neoplastic transformation. On the basis of this information, we have analysed TSG101 gene expression in 20 human papillary thyroid carcinomas (PTCs) by immunohistochemistry and demonstrated that the overexpression of TSG101 protein is closely associated with human PTCs. Further sequence analysis reveals no mutation in cDNA region encoding steadiness box in these PTC specimens, indicating that the upregulation of TSG101 protein is not caused by the alteration of this region. In situ hybridization analysis confirms that overexpression of TSG101 also occurs at the transcriptional level. In addition, semi-quantitative RT-PCR and subsequent Southern hybridization verify that the amounts of TSG101 transcripts are indeed lower in three normal thyroid tissues than in PTC specimens. Here we report the upregulation of TSG101 expression in PTC cells, providing the first evidence of the association of TSG101 overexpression with human tumors and suggesting that upregulation of TSG101 steady-state level might play a role in mediating tumorigenesis of human PTC.

Prognostic significance of molecular genetic aberrations on chromosome segment 11p15.5 in non-small-cell lung cancer

PURPOSE

The assessment of prognosis and decisions on treatment for patients with non-small-cell lung cancer (NSCLC) are determined on the basis of disease stage and performance status. NSCLC frequently manifests loss of heterozygosity (LOH) at chromosome segment 11p15.5. Whether LOH at 11p15.5 is an independent prognostic variable has yet to be determined.

PATIENTS AND METHODS

We developed five novel markers, which can be assessed by polymerase chain reaction and restriction enzyme digestion. LOH at 11p15.5 was assessed in 193 patients who underwent surgical resection for pathologic stage I and II of the disease.

RESULTS

LOH at 11p15.5 was associated with poor survival (P =.021). Multivariate logistic regression analysis showed that after disease stage, performance status, weight loss, sex, age at diagnosis, and smoking history were controlled for, patients with LOH were two times more likely to die than those without LOH (relative risk [RR] = 2.01, P =.021). Cox regression analysis with disease stage and LOH revealed that the survival of patients with stage I disease and LOH was similar to the survival of patients with stage II disease, and it was significantly worse than the survival of stage I patients without LOH (RR = 2.38, P =.038).

CONCLUSION

LOH in a 310-kb region on chromosome segment 11p15.5 that includes the gene for the regulatory subunit of the enzyme ribonucleotide reductase is highly predictive of poor survival from NSCLC. The future utility of analysis of the allelic status of this region may involve treatment decisions, such as the use of neoadjuvant and adjuvant chemotherapy for patients with stage I disease.

Reduced expression of the REIC/Dkk-3 gene by promoter-hypermethylation in human tumor cells

The human REIC gene is a recently found mortalization-related gene and a candidate tumor suppressor gene expression of which is largely attenuated in many immortalized and tumor-derived cell lines (Biochem. Biophys. Res. Commun. 268 (2000) 20-24). To gain insight into the mechanisms of the down-regulation, we investigated the genomic structure and promoter activity of the human REIC gene. The gene, identical with the DKK-3 gene, resides on chromosome 11p15.1, consists of nine exons, and has two promoters. Methylation in the main promoter region was detected in 11 out of 21 cell lines tested (52%) derived from a variety of human tumors, in which the expression of the REIC gene was decreased. In ten of these 11 cell lines the minor promoter was also methylated. Similarly, the REIC gene expression was decreased in 14 of 24 fresh non-small cell lung cancer specimens (58%) compared to that in corresponding non-cancerous tissue, though allelic loss and tumor-specific mutation were rare. Of these 14 tumors, at least five tumors exhibited heavy methylation of the REIC promoter region. These results indicate that the down-regulation of the REIC gene expression is ascribed to the aberrant promoter hyper-methylation at least in a subset of human tumors. The expression was restored upon treatment of SQ5 cells with 5-aza-deoxycytidine, confirming DNA methylation as the mode of downregulation. A notable single nucleotide polymorphism in the coding region (cSNP) with an amino acid substitution of glycine (GGG) to arginine (AGG) was found at codon 335 of the REIC gene. However, the distribution of the cSNP showed no significant difference between lung cancer patients and healthy population.

Microsatellite alteration at chromosome 11 in primary human nasopharyngeal carcinoma in Taiwan

Nasopharyngeal carcinoma (NPC) is one of the common cancers in Taiwan but is rare in western countries. The development of NPC involves multiple genetic changes in tumorigenesis and progression of the disease. To better understand genetic alterations in chromosome 11 which occur in human (NPC), we examined tumor specimens and corresponding non-cancerous tissue from 30 cases of NPC, using five microsatellite polymorphic markers whose location has previously been defined. To determine the clinical characteristics of MSI(+) or LOH, we performed correlation analysis of the findings with clinicopathological parameters. Loss of heterozygosity (LOH) was identified in 18 (60%) of 30 cases on at least one of the five markers. A high frequency of LOH was found at the two loci: D11S912 (7/30, 23.33%) and D11S934 (6/30, 20.00%), both of which are located within 11q23-24. We also found that 14 specimens (14/30, 46.67%) exhibited microsatellite instability (MSI(+)). Five (5/30, 16.67%) specimens exhibited MSI(+) in the transformation growth factor beta receptor type II (TGF-beta RII) exon 3 which also exhibited on chromosome 11. LOH was found to be significantly correlated with the T (tumor size) value (P=0.022) of Ho's system. MSI(+) showed a significant correlation with the N (lymph node) value of the UICC system (P=0.031). Our results suggest that multiple putative tumor suppressor genes on chromosome 11 play a role in the development of NPC. MSI(+) expression showed a predisposition to occur in the late stage of NPC while LOH tended to occur in early stages of NPC. The behavior of mutated TGF-beta RII exon 3, which appeared to serve as a dysfunction brake during nasopharyngeal carcinogenesis, may be a target gene in the defected mismatch repair system.

Transcript map and complete genomic sequence for the 310 kb region of minimal allele loss on chromosome segment 11p15.5 in non-small-cell lung cancer

Molecular, functional, and clinical analyses strongly suggest that chromosome segment 11p15.5 contains a gene involved in lung cancer pathogenesis. The critical region of allele loss is 310 kb in size. We used our contig of P1-phage artificial chromosome (PAC) clones together with newly identified bacterial artificial chromosome (BAC) clones and the draft human genome sequence to complete a contiguous string of 380 407 bp. Three PAC clones that span the region were used to identify transcripts by exon trapping. Computational gene prediction algorithms were used to query the sequence for potential genes and exons. Screening for expression was performed with tissue-specific and cell line derived mRNA arrays. The region contains the complete SSA/Ro52 and RRM1 genes, exons 7-12 of the GOK gene, and the psirad pseudo-gene. A cluster of six nearly identical genes with an intact open reading frame (ORF) of 585 bp that share 75% identity with the HSPC182 gene was found. In addition, five putative novel genes were identified. Sequence tagged sites (STS) and polymorphic markers were used to screen 117 lung cancer cell lines for homozygous deletions and none were identified. These data provide the basis for the identification of a lung cancer suppressor gene on 11p15.5.

Antiproliferative activity of REIC/Dkk-3 and its significant down-regulation in non-small-cell lung carcinomas

We recently reported the cloning of the REIC/Dkk-3 gene, whose expression was shown to be down-regulated in many human immortalized and tumor-derived cell lines [T. Tsuji et al. (2000) Biochem. Biophys. Res. Commun. 268, 20-24]. In the present study, we demonstrated that expression of the exogenous REIC/Dkk-3 gene in tumor cells inhibited cell growth. Furthermore, the level of REIC/Dkk-3 mRNA in normal human cells was lowest in the late G(1) phase during the cell cycle. Then we found that the expression of REIC/Dkk-3 was significantly down-regulated in surgically resected non-small-cell lung carcinomas. We determined the REIC/Dkk-3 locus on chromosome 11p15, where loss of heterozygosity has frequently been observed in human tumors. These findings indicate that REIC/Dkk-3 may function as a tumor suppressor.

SSA/RO52gene and expressed sequence tags in an 85 kb region of chromosome segment 11p15.5

Frequent allelic loss in lung cancer has been described in a region on chromosome segment 11p15.5 (LOH11A). The region is approximately 650 kb in size and flanked by the markers D11S988 centromeric and D11S860 telomeric. Clinical and cell biological studies suggest that it contains a gene associated with metastatic tumor spread. One of the genes identified within this region is SSA/Ro52, which has a RING finger domain and may be involved in gene regulation. We studied this gene for mutations using SSCP analysis and for expression using RT-PCR and Western blotting on lung cancer cell lines and tumor-normal tissue pairs. No mutations and no differences in mRNA or protein expression between tumor tissue and normal tissue pairs were identified. We discovered a novel polymorphic site (SSA44C/T) within exon 1 of this gene. Among 141 primary lung cancers, allelic loss was observed in 16% of informative cases. Our analyses excluded SSA/Ro52 as a tumor-suppressor gene in lung cancer and newly defined the centromeric border of the LOH11A region from D11S988 previously to SSA44C/T. This reduced the region of the putative suppressor gene to 460 to 485 kb. A significant difference (p = 0.01) in the frequency of alleles for this polymorphism between Caucasians and African-Americans was observed. The "T" allele frequency was 0.12 in Caucasians and 0.23 in African-Americans. A genomic EcoRI map over 85 kb surrounding the SSA/Ro52 gene was constructed, and 4 expressed sequence tags were identified by sequencing and studied.

Amplotyping of microdissected, methanol-fixed lung carcinoma by arbitrarily primed polymerase chain reaction

The arbitrarily primed polymerase chain reaction (AP-PCR) was used to detect somatic genetic alterations in lung carcinomas. DNA fingerprints generated by a single arbitrary primer were compared between normal and tumor tissues of the same individuals. We adapted the technique to the use of tissue fixed with methanol, which allowed the analysis of small areas of tissue by microdissection. This improvement of the fingerprinting technique permitted the study of tumors at early stages of progression. Loss of sequences from chromosome 7 was detected in 41.7% of adenocarcinomas and from chromosome 22 in 84.6% of small-cell carcinomas. Gains of sequences from chromosomes 1, 8 and 13 were detected in more than 40% of adenocarcinomas and in chromosome 2 in 63.3% of squamous-cell carcinomas. Our results indicate that allelic imbalances at these chromosomal regions are common genetic abnormalities in lung carcinomas. Loss of sequences from chromosome 22q13.3, found in 11 of 13 small-cell carcinomas, were confirmed by microsatellite PCR analysis. We show that the use of our improved AP-PCR fingerprinting permits the detection of both losses and gains of novel chromosomal regions early during lung cancer development. Our results indicate that early-stage tumors tend to have more allelic imbalances than relatively advanced tumors, suggesting a high tumor genetic heterogeneity in the early stages of lung tumor progression.

Analysis of aberrant transcription of TSG101 in hepatocellular carcinomas

A variety of studies suggest that tumour suppressor loci on chromosome 11p are important in various forms of human neoplasia. Recently, a gene located at the chromosome 11p 15.1-15.2 region called TSG101 was discovered and proposed as a candidate tumour suppressor gene in breast cancers. We evaluated the TSG101 gene in a panel of liver cancer cell lines and paired tumours and non-malignant tissues. In this study, four of the seven (57%) cell lines, eight of the 18 (44%) tumours and four of the 18 (22%) non-malignant liver tissues exhibited aberrant TSG101 transcripts by nested reverse transcription-polymerase chain reaction (RT-PCR) analysis. However, a normal-sized transcript without sequence abnormalities verified by single-stranded conformation polymorphism (SSCP) analysis was expressed at robust levels in all the cell lines and most of the tissue samples tested. In addition, Southern blot analysis could identify no genomic abnormalities of the gene. Our results suggest either that the TSG101 gene may not be involved in hepatocarcinogenesis or that it plays a role in the development and/or progress of hepatocellular carcinomas through an unusual mechanism.

A 1.4-Mb high-resolution physical map and contig of chromosome segment 11p15.5 and genes in the LOH11A metastasis suppressor region

The centromeric part of chromosome segment 11p15.5 contains a region of frequent allele loss in many adult solid malignancies. This region, called LOH11A, is lost in 75% of lung cancers and is thought to contain a gene that may function as a metastasis suppressor. Genetic complementation studies have shown suppression of the malignant phenotype including reduction of metastasis formation. We constructed a high-resolution physical map and contig over 1.4 Mb that includes the beta-hemoglobin gene cluster and the gene for the large subunit of ribonucleotide reductase (RRM1). Through sequencing and computerized analysis, we determined that this region contains an unusually large number of transposable elements, which suggests that double-stranded DNA breaks occur frequently here. Twenty-two putative genes were identified. Because of its location at the site of maximal allele loss in the 650-kb LOH11A region and previous functional studies, RRM1 is the most likely candidate gene with metastasis suppressor function. The malignant phenotype, in this case, results from a relative loss of function rather than a complete loss.

Multiple truncated transcripts of TSG101 in gastrointestinal cancers

The candidate tumour suppressor gene TSG101, located on chromosome 11p15, has been associated with frequent intragenic deletion in uncultured primary human breast cancers. Using paired tumour and normal tissues from surgical specimens, we performed nested reverse transcriptase-polymerase chain reaction and direct sequencing to analyse TSG101 exons 1-6 from 32 gastric, 30 colorectal and 16 oesophageal cancers. Truncated transcripts, were found in both tumour and normal tissues from the stomach (15.6 and 12.5%), colon (13.3 and 3.3%) and oesophagus (25 and 25%). Multiple truncated transcripts in individual specimens were also observed. Two types of splicing patterns, one with three to six bases homology at the deletion junction (25.9%), the other with donor site 5' GT and acceptor site 3' AG (55.6%), were the most common patterns. We conclude that in gastrointestinal cancers, truncated transcripts of TSG101 gene occur not uncommonly and do so with a specific splicing pattern.

Loss of heterozygosity on chromosome 11p15 during histological progression in microdissected ductal carcinoma of the breast

Microdissection of histologically identifiable components from formalin-fixed, paraffin-embedded tissue sections allows molecular genetic analyses to be correlated directly with pathological findings. In this study, we have characterized loss of heterozygosity (LOH) at chromosome 11p15 at different stages of progression in microdissected tumor components from 115 ductal carcinomas of the breast. Microdissected foci of intraductal, infiltrating, and metastatic tumors were analyzed to determine the stage of progression at which LOH at 11p15 occurs. LOH was detected in 43 (37%) of 115 cases. Foci of intraductal carcinoma could be microdissected from 85 cases, of which 30 (35%) showed LOH at some stage of progression. LOH was detected in the intraductal component in 26 of these 30 cases. Interstitial deletions were characterized by using a panel of 10 highly polymorphic markers. The smallest region of overlap (SRO) for LOH at 11p15 was bounded by the markers D11S4046 and D11S1758. LOH at 11p15.5 showed no correlation with estrogen receptor status, the presence of positive lymph nodes, tumor size, histological grade, or long-term survival. We conclude that 11p15 LOH usually occurs early in breast cancer development but less frequently does not develop until the infiltrating or metastatic stages of tumor progression.

Analysis of loss of heterozygosity in small adenocarcinomas of the lung

BACKGROUND

Despite the many studies of genetic alterations in advanced lung carcinomas, few reports have analyzed early stage adenocarcinoma of the lung.

METHODS

We focused on small pulmonary adenocarcinomas, classified according to recently proposed histological criteria (Noguchi M., et al. Cancer 1995;75:2844-52) which divided adenocarcinomas 2 cm or less in diameter into two groups; one showing replacing growth of the pulmonary alveolar structure [A, localized bronchioloalveolar carcinoma (LBAC); B, LBAC with alveolar collapse; C, LBAC with active fibroblastic proliferation] and the other showing non-replacing growth (D, poorly differentiated adenocarcinoma). Ninety-four small pulmonary adenocarcinomas, including 40 of type A and B, 30 of type C and 24 of type D, were examined for loss of heterozygosity (LOH) using microsatellite markers.

RESULTS

The frequencies of LOH were 19.8% in types A and B, 26.8% in type C and 32.7% in type D tumors. There were no significant differences in the frequency of LOH on chromosomes 2p, 3p, 9p and 17q among tumor types. However, on 17p, the frequency of LOH was significantly lower for types A and B than for type C or D. Three out of six type C tumors which were positive for LOH at several loci showed different LOH patterns in two areas (central and peripheral regions).

CONCLUSIONS

Allelic losses were detected in very early adenocarcinomas and the frequency of LOHs on chromosome 17p increased during malignant progression of the tumor. Heterogeneous genetic alterations were demonstrated even in small pulmonary adenocarcinomas.

Cytogenetic findings in thirty lung carcinoma patients

Primary tissue cultures of human lung tumors were prepared from 30 cases of which 16 were diagnosed as squamous cell carcinoma, six adenocarcinoma, four adenosquamous cell carcinoma, three large cell carcinoma, and one small cell lung carcinoma. Chromosomal abnormalities were observed in 26 cases by cytogenetic studies with a GTG banding technique. Specific chromosome bands frequently involved in structural abnormalities were seen on 1p11, 1q11, 2p10, 6p10, 7q11, 7q22, 7q32, 8q22, 9q22, 11q11, 21q10, and Xq24. We assumed that especially i(2)(p10), i(9)(p10), i(21)(q10), t(11;12), t(14;15), del(X)(q24), and loss of the Y chromosome may play a role in the development of lung cancer as secondary changes. In this way, our cytogenetic findings provide evidence that multiple genetic lesions are associated with the pathogenesis of lung cancer.

In vitro confirmation of newly established lung cancer cell lines using flow cytometry and multicellular tumor spheroids

We report on a simplified method of cytomorphological in vitro confirmation of newly established lung cancer cell lines by using multicellular tumor spheroids (MTS) and flow cytometry (FCM). Eleven cell lines were established from 11 patients with lung cancer. The MTS were produced by culturing cells in agar-coated dish. Cytomorphological studies were made using smears of crushed MTS and frozen sections of MTS. The MTS were fixed doubly with paraformaldehyde and osmic acid for scanning and transmission electron microscopy. Bivariate fluorescence of fluorescein isothyocyanate (FITC, tumor associated antigen, TAA) and propidium iodide (DNA) were measured by FCM. The MTS grew anchorage-independently. Cytopathological and electron microscopic findings of MTS were similar to those of the original clinical specimens. The DNA index and TAA were useful in evaluating the presence or absence of contamination by cells of non-tumor origin. The new cell lines satisfied a minimum of four conditions to confirm their establishment: (a) they originated from humans, (b) they were cytomorphologically identified with specimens from primary lesions, (c) they showed tumorigenicity, and (d) they were free from contamination by cells of different origin. From these findings, the establishment of new cell lines can be confirmed in vitro by using MTS and FCM.

Delineation of the centromeric and telomeric chromosome segment 11p15.5 lung cancer suppressor regions LOH11A and LOH11B

We have reported frequent allele loss for two separate regions identified by the markers D11S12 and HRAS on chromosome 11p15.5. D11S12 allele loss was associated with tumor stage and type and HRAS allele loss with cigarette consumption, sex, and survival. To positionally clone the putative tumor suppressor genes located in these regions, we here report a reduction in the size of these intervals to approximately 250 kb. The markers used, ordered from centromere to telomere, were D11S932 -D11S1331-D11S1760-D11S1323-D11S4891 (HBB)-D11S1758-D11S12-D11S988-D11S860-D11S131 8-TH-HRAS-D11S1363-D11S2071. We analyzed 44 tissue pairs from patients with primary lung cancer. The smallest common regions of allele loss were located between D11S1758 and D11S12 in the centromeric region of chromosome segment 11p15.5 (region of LOH on chromosome 11 in lung cancer, LOH11A) and between HRAS and D11S1363 in the telomeric region (region of LOH on chromosome 11 in lung cancer, LOH11B). Loss of heterozygosity was observed in 24/39 (62%) primary lung cancers informative for LOH11A and in 17/34 (50%) informative for LOH11B. The pattern of allele loss strongly suggests that two lung cancer suppressor genes are located on chromosome segment 11p15.5, one between D11S1758 and D11S12 and the other between HRAS and D11S1363. The estimated physical size of each of these regions is 250 kb.

The TSG101 tumor susceptibility gene is located in chromosome 11 band p15 and is mutated in human breast cancer

Recent work has identified a mouse gene (tsg101) whose inactivation in fibroblasts results in cellular transformation and the ability to produce metastatic tumors in nude mice. Here, we report that the human homolog, TSG101, which we isolated and mapped to chromosome 11, bands 15.1-15.2, a region proposed to contain tumor suppressor gene(s), is mutated at high frequency in human breast cancer. In 7 of 15 uncultured primary human breast carcinomas, intragenic deletions were shown in TSG101 genomic DNA and transcripts by gel and sequence analysis, and mutations affecting two TSG101 alleles were identified in four of these cancers. No TSG101 defects were found in matched normal breast tissue from the breast cancer patients. These findings strongly implicate TSG101 mutations in human breast cancer.

Deletion mapping of chromosome 2 in human lung carcinoma

Sixty-three non-small cell lung carcinomas (NSCLCs) and 20 small cell lung carcinomas (SCLCs) were examined for loss of heterozygosity (LOH) on chromosome 2. Fifteen highly polymorphic dinucleotide markers spanning both the short and long arms of chromosome 2 were selected for a polymerase chain reaction (PCR)-based fine mapping. They included a DNA marker localized in the homozygously deleted region at 2q33, which we previously identified in an SCLC cell line. LOH on chromosome arm 2q was detected in 23/63 (37%) of NSCLC and 6/20 (30%) of SCLC, while LOH on 2p was observed in 14/56 (25%) and 4/17 (24%), respectively. There were two commonly deleted regions mapped to 2q32-q37 and 2p16-pter, and the homozygously deleted region at 2q33 was in the commonly deleted region on 2q. In NSCLC, the incidence of LOH on 2p and 2q was significantly higher in brain metastases than in primary tumors (P = 0.005 and 0.001, respectively). In addition, LOH on chromosome arm 2q occurred more frequently in moderately/poorly differentiated tumors than in well-differentiated tumors (P = 0.046). These results suggested that inactivation of tumor suppressor genes on chromosome 2 is involved in the phenotypic alterations of NSCLC cells into more aggressive ones.

Loss of chromosome 11 and 11 p/q imbalances in bladder cancer detected by fluorescence in situ hybridization

To identify chromosomal imbalances in non-diploid transitional-cell carcinoma (TCC) of the bladder we performed double-target in situ hybridization (FISH), using the centromeric probe for chromosome 11 together with 2 cosmid probes located on the 11p and 11q arm in the proximity of the telomere. The FISH protocol was optimized to ensure a highly efficient and reproducible detectability of all 3 targets. As a consequence, it was possible to calculate ratios between the number of spots obtained with cosmid and centromere probes. Furthermore, the number of chromosomes 11 present was compared with the DNA index and the chromosome ploidy as obtained with other chromosome centromere probes. In this study we found that: (i) in 54 diploid TCCs a monosomy for chromosome 11 was detected in only one case; (ii) chromosome 11 was completely lost in 9 of 16 non-diploid TCCs; (iii) in 8 of these 16 non-diploid tumors an imbalance was observed between the 11p and 11q arm, in 4 of these cases a complete loss of chromosome 11 being observed in addition; (iv) the copy number counted for 11q was always identical to the 11 centromere number, except in one case, indicating a loss of 11p in the cases with imbalances. In total, 13 of 16 non-diploid TCCs (81%) showed either a loss of a complete chromosome 11, of (part of) the 11p arm, or both. Therefore we concluded that during tetra- or aneuploidization in TCCs, (part of) chromosome 11 is lost. In addition, our results indicate that under-representation of chromosome 11p occurs in the majority of the tumor cells, supporting the idea that loss of these sequences is an important step in the development of TCC.

Lung pathology: the molecular genetics of non-small cell lung cancer

In Australia, lung cancer is the most common malignancy in males and the largest cause of cancer deaths. Conventional management has not had a dramatic impact on the mortality rates from lung cancer, which has a case-fatality rate of over 90%. Recent developments in molecular and cellular biology have however, contributed to our knowledge of lung tumorigenesis, which will hopefully translate into clinical benefit for our patients. Many molecular abnormalities are common to both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) but there are differences between these histological types and even within the NSCLC subtypes. This review concentrates on NSCLC, which accounts for up to 85% of Australian lung cancers.

CpG island clones for chromosome 11p--a resource for mapping and gene identification

A NotI end fragment library has been constructed for human Chromosome (Chr) 11p. Seventy-two clones were mapped to chromosomal subregions by use of somatic cell hybrids. The clones detect 44 different CpG islands, and we have isolated cosmid contigs for 36 of them. Extrapolation from the known 11p13 NotI restriction map suggests that every second CpG island from 11p containing a Not site is already represented in the clone collection. By sequence analysis all of the 11p13 clones exhibit typical features of CpG islands, and cross-species hybridization has been detected with at least one fragment in most cases. The cosmids serve as valuable linking clones for long-range restriction mapping. They also provide excellent starting material for transcript isolation procedures to identify genes on chromosome 11p associated with developmental anomalies and various tumor types. Several transcribed sequences have already been isolated with some of these clones.

Allelic losses in human chromosome 11 in lung cancers

The relatively frequent loss of heterozygosity at loci on the short arm of chromosome 11 in human lung cancers has suggested the presence of a putative tumor suppressor gene. For location of the gene, a fine deletion map of human chromosome 11 was constructed by analysis of DNAs from 79 lung cancers with 31 sequence-tagged-site markers that dotted chromosome 11 and detected polymorphic changes in nucleotide sequences. The results showed that three regions, 11p12-p15, 11q12, and 11q14-q24, were commonly deleted in a considerable number of cancers, indicating the possible presence of more than one tumor suppressor gene. The range of deletion in the 11p15 region was estimated to be 4.5 megabases. That in the 11q24-q24 region was divided into two portions: one was 3 cM in length, and the other was longer and could not be specified because of lack of appropriate markers. The deletion in the 11q12 region was so short that two markers flanking the region could not be identified by genetic analysis.

Deletion mapping of chromosome 11 in carcinoma of the bladder

Deletions of the short arm of chromosome 11 have been identified by both cytogenetic and molecular criteria in bladder and other types of solid tumor, indicating the presence of one or more suppressor loci in this region. To localize the 11p deletion target(s) more precisely and to screen for loss of heterozygosity (LOH) on the long arm of the chromosome, 100 bladder tumors were analyzed for LOH on chromosome 11 using restriction fragment length polymorphisms (RFLPs) and microsatellite markers mapped to both 11p and 11q. Thirty-four tumors were found to have LOH at 1 or more loci. Of these, 17 had LOH restricted to 11p, 13 had LOH of both 11p and 11q, and 4 had LOH of 11q only. Eight tumors showed LOH at all informative loci indicating probable loss of an entire copy of chromosome 11. A common region of deletion was defined on 11p between D11S922 (11p15.5) and D11S569 (11p15.1-15.2). This region does not include the HRAS or WT1 loci (at 11p15.5 and 11p13, respectively). Seventeen tumors had LOH on 11q, 4 of which had LOH on 11q only. The common region of deletion on 11q was between FGF3 and D11S490 (11q13-q23.2). Two tumors showed LOH on both 11p and 11q with a clear region of retention of heterozygosity between, indicating the existence of two deletion targets on chromosome 11.

Cytogenetic analysis of short-term cultured squamous cell carcinomas of the lung

Cytogenetic analysis of 122 primary squamous cell carcinomas of the lung revealed clonal abnormalities in 56 tumors. Karyotypes with simple numerical changes were found in 32 tumors: 45,X,-Y in 28, 47,XY,+7/45,X-Y, in two, 47,XY,+Y/45,X,-Y and 47,XY,+20/45,X,-Y in one tumor each. A super-numerary ring chromosome was the sole anomaly in two tumors. Complex structural changes were found in 22 tumors. The chromosomes most frequently involved in structural rearrangements were chromosomes 1 (15 tumors), 3, 7, and 11 (10 tumors each), 5 and 6 (nine tumors each), and 2, 8, and 12 (eight tumors each). The bands and regions most often affected were 1p11-13 and 5cen (six tumors each), 11p11, 14p11-13, 15cen, and 17p11-12 (five tumors each), and 12p13 and 13cen (four tumors each). The only recurrent changes were the whole-arm rearrangements i(5)(p10) (five tumors) and i(6)(p10), der(9;15)(q10;q10), and der(13;15)(q10;q10) (two tumors each). The most prominent genomic imbalances were, apart from losses of the Y chromosome, losses from 1p, 3p, 5q, 6q, 8p, 13p, and 14p and gains from 1q and 5p.

Correlation of loss of heterozygosity at 11p with tumour progression and survival in non-small cell lung cancer

Loss of heterozygosity (LOH) affecting loci at 11p13 and 11p15 occurs in childhood and adult carcinomas, including non-small cell lung cancer (NSCLC). In NSCLC, the highest reported frequency of LOH was 72% at the 11p13 catalase (CAT) locus. As this locus is centromeric to the Wilms' tumour (WT1) locus, possible involvement of WT1 in the pathogenesis of NSCLC was considered. We thus examined 101 cases of NSCLC for LOH at the WT1 and five other polymorphic loci along 11p. At 11p13, the frequencies of LOH were 20% (9/46) at the FSHB locus, 9% (5/53) at the WT1 locus, and 15% (6/41) at the CAT locus. The shortest region of overlap (SRO) at 11p13 was mapped centromeric to, but excluding, the WT1 locus. Only adenocarcinomas showed LOH in this region. At 11p15, LOH affected 23% (18/77) of informative cases, with the highest frequency of 36% at the insulin (INS) locus. The SRO at 11p15 was mapped telomeric to the RRM1 locus. A third region, at 11p13-15 between WT1 and RRM1, was also affected by LOH. LOH at 11p correlated significantly with advanced T stage and nodal involvement in NSCLC tumours. In the squamous cell carcinoma subtype, LOH along 11p also correlated with nodal involvement. Furthermore, squamous tumours with LOH involving 11p13 loci had significantly worse survival than those without LOH. These data suggest that tumor suppressor gene(s) on 11p affect the progression of NSCLC, particularly squamous cell carcinomas.

Biology of lung cancer

While the overall survival of patients with lung cancer has remained relatively unchanged over the past decade, there have been major advances in our understanding of the biology of small cell and non-small cell lung cancer through the study of lung cancer cell lines. Surface molecules associated with lung cancer have been identified and their molecular structure and function are being elucidated. Growth factors which stimulate the lung cancer cells in an autocrine fashion have been identified. Genetic changes of lung cancer cells have been defined on a chromosomal and a molecular level. This review summarizes many biologic properties of lung cancer cells that have been described in the literature.

Chromosomal localisation of two putative 11p oncosuppressor genes involved in human ovarian tumours

In this study, 44 primary or metastatic human ovarian tumours were tested for allelic deletions on the short arm of chromosome 11. Analysis of 12 polymorphic loci by Southern blotting evidenced loss of heterozygosity (LOH) in at least one locus in 41% of cases. Moreover, two hot spots of deletions were tentatively mapped on 11p13 and 11p15.5. Our results demonstrated that LOH at 11p is a common event in ovarian carcinomas and were indicative of the possible existence in 11p of two oncosuppressor genes involved in ovarian carcinogenesis. The similarity observed with 11p allelic losses in Wilms tumours, clustered in 11p13 and 11p15.5 too, suggests that deletion and possibly inactivation of the same growth regulatory genes (WT genes) could also contribute to development of the malignant phenotype in ovarian carcinomas. Finally, a statistically significant association (P = 0.005) between 11p deletions and hepatic involvement was suggested by the analysis of distribution of 11p LOH relative to different clinical and pathological parameters of the tumour patients.