DSpace Angular :: Browsing by Author "Gazdar, AF"

Browsing by Author "Gazdar, AF"

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Allelic losses at chromosome 8p21-23 are early and frequent events in the pathogenesis of lung cancer
(AMER ASSOC CANCER RESEARCH, 1999) Wistuba, II; Behrens, C; Virmani, AK; Milchgrub, S; Syed, S; Lam, S; Mackay, B; Minna, JD; Gazdar, AF
Allelic Losses on the short arm of chromosome 8 (8p) have been reported as frequent events in several cancers, including Lung. However, no comprehensive mapping analysis of chromosome 8p in Lung cancer tumors has been performed, and no data are available about the stage at which these abnormalities occur during the multistage development of lung cancer. Using 26 microsatellite markers, we mapped the chromosome 8 regions frequently deleted in lung cancer in 13 small cell carcinoma and 17 non-small cell lung carcinoma cell Lines and in 68 microdissected archival primary lung tumors (22 small cell lung carcinomas, 25 squamous cell carcinomas, and 21 adenocarcinomas), We also studied the role of 8p deletions in lung cancer pathogenesis by examining 95 microdissected normal epithelium and preneoplastic samples from 11 surgically resected squamous cell Lung carcinomas and from 58 bronchoscopy biopsy samples obtained from 31 current and former smokers. High frequencies of deletions at 8p21-23 regions were detected in lung cancer cell lines and in primary lung tumors. Deletions commenced early during the multistage development of lung cancer at the hyperplasia/metaplasia stage in cancer patients and in smokers without cancer. Allelic deletions persisted for up to 48 years after smoking cessation. There was a progressive increase of the overall 8p21-23 loss of heterozygosity frequency and in the size of the deleted region with increasing severity of histopathological preneoplastic changes. In epithelial samples from resected squamous cell Lung carcinomas, we compared the presence of loss of heterozygosity at 8p21-23 with deletions at chromosomes 3p and 9p, Of interest, the pattern of deletions was not random, and 8p21-23 allelic Losses always followed 3p deletions and usually followed 9p deletions. We conclude that 8p21-23 deletions are frequent and early events in the pathogenesis of Lung carcinomas.
Analysis of the FHIT gene and FRA3B region in sporadic breast cancer, preneoplastic lesions, and familial breast cancer probands
(1997) Ahmadian, M; Wistuba, II; Fong, KM; Behrens, C; Kodagoda, DR; Saboorian, MH; Shay, J; Tomlinson, GE; Blum, J; Minna, JD; Gazdar, AF
The FHIT gene, which spans the FRA3B fragile site at chromosome 3p14.2 is a candidate tumor suppressor gene in breast and other cancers. We investigated FHIT and FRA3B for loss of heterozygosity (LOH); homozygous deletions; abnormal transcripts; and acquired/germ-line point mutations in breast cancer cell lines (n = 32), breast epithelial and stromal cell cultures (n = 18), microdissected invasive (n = 16) and ductal in situ carcinomas (n = 6), and their accompanying normal and abnormal epithelial foci (n = 14). LOH at 3p14.2, especially at FHIT intragenic marker D3S1300, was found in 6 of 16 microdissected invasive tumors and 3 of 6 ductal in situ carcinomas. In accompanying preneoplastic foci, LOH occurred in two of eight intraductal hyperplasias but not in histologically normal ductal epithelium (n = 6). Three of 32 (9%) breast cancer cell lines demonstrated homozygous deletions of FHIT exon 4 (two cases) and exon 5 (one case), which correlated with exon 4-deleted transcripts and loss of the cDNA transcript containing the coding exons 5-9, respectively. Normal mammary cultures and 31 or 32 tumor cell lines (97%) expressed wild-type coding transcripts as well as a minor exon 5-deleted message. Single-strand conformation polymorphism analysis of the coding exons in the 32 tumor and 18 normal breast cell lines and their sequencing revealed four silent polymorphisms and a germ-line histidine triad point mutation (651 G-->T) in a tumor arising in a 70-year-old woman. This mutation was also present in one of her two thus far unaffected daughters. Analysis of additional DNAs from 280 probands of high-risk breast cancer families for other FHIT exon 8 mutations detected an intronic point mutation 13 bases upstream of exon 8. Thus, we have demonstrated relatively early abnormalities of the FHIT/FRA3B region in breast cancer and discovered two rare FHIT germ-line mutations. The expression of a transcript containing the coding exons in nearly all cell lines, including those with germ-line mutations, suggests the possibility that another gene in the FRA3B region may be involved in the pathogenesis of breast cancer.
Comparison of features of human breast cancer cell lines and their corresponding tumors
(AMER ASSOC CANCER RESEARCH, 1998) Wistuba, II; Behrens, C; Milchgrub, S; Syed, S; Ahmadian, M; Virmani, AK; Kurvari, V; Cunningham, TH; Ashfaq, R; Minna, JD; Gazdar, AF
Although human tumor-derived cell lines play an important role in the investigation of cancer biology and genetics, there is no comprehensive study comparing tumor cell line properties with those of the individual tumors from which they were derived. We compared the properties of a series of 18 human breast cancer cell lines that were cultured for a median period of 25 months (range, 9-60 months) and their corresponding archival tumor tissues. We compared morphological characteristics, ploidy, and immunohistochemical expression of estrogen receptors, progesterone receptors, and HER2/neu and p53 proteins. For 17 of these cases, we also tested for allelic losses at 18 chromosomal regions frequently deleted in breast tumors using 51 polymorphic microsatellite markers, and we determined the TP53 gene mutation status in exons 5 to 10, There was an excellent correlation between the breast tumor cell lines and their corresponding tumor tissues for morphological features (100%); presence of aneuploidy (87%); immunohistochemical expression of estrogen receptors (87%), progesterone receptors (73%), and HER2/neu (93%) and p53 proteins (100%); allelic loss at all of the chromosomal regions analyzed (82-100% concordance); and TP53 gene mutations (75%), The same parental allele was lost in 279 (99%) of 281 of the comparisons of allele losses. The fractional allelic loss indices (a reflection of the total allelic loss) of the cell lines and their corresponding tumor tissues were identical or similar in 15 (88%) of 17 paired comparisons, Although our previous studies (A, Gazdar et at, Int. J, Cancer, in press) indicated that only a subset of primary breast carcinomas that have several features indicative of advanced tumors with poor prognosis can be successfully cultured, the cell lines retain the properties of their parental tumors for lengthy culture periods and, thus, provide suitable model systems for biomedical studies.
Comparison of features of human lung cancer cell lines and their corresponding tumors
(AMER ASSOC CANCER RESEARCH, 1999) Wistuba, II; Bryant, D; Behrens, C; Milchgrub, S; Virmani, AK; Ashfaq, R; Minna, JD; Gazdar, AF
Although human lung tumor-derived cell lines play an important role in the investigation of lung cancer biology and genetics, there is no comprehensive study comparing the genotypic and phenotypic properties of lung cancer cell lines with those of the individual tumors from which they were derived, We compared a variety of properties of 12 human non-small cell lung carcinoma (NSCLC) cell lines (cultured for a median period of 39 months; range, 12-69) and their corresponding archival tumor tissues. There was, in general, an excellent concordance between the lung tumor cell lines and their corresponding tumor tissues for morphology (100%), the presence of aneuploidy (100%), immunohistochemical expression of HER2/neu (100%) and p53 proteins (100%), loss of heterozygosity at 13 chromosomal regions analyzed (97%) using 37 microsatellite markers, microsatellite alterations (MAs, 75%), TP53 (67%), and K-ras (100%) gene mutations, In addition, there was 100% concordance for the parental allele lost in all 115 comparisons of allelic losses. Some discrepancies were found; more aneuploid subpopulations of cells were detected in the cell lines as well as higher incidences of TP53 mutations (4 of 10 mutations not found in the tumors) and microsatellite alterations (two cell lines with MAs not detected in the tumors). Similar loss of heterozygosity frequencies by chromosomal regions and mean fractional allelic loss index were detected between successfully cultured and 40 uncultured lung tumors (0.45 and 0.49, respectively), indicating that both groups were similar. Our findings indicate that the NSCLC cell lines in the large majority of instances retain the properties of their parental tumors for lengthy culture periods. NSCLC cell lines appear very representative of the lung cancer tumor from which they were derived and thus provide suitable model systems for biomedical studies of this important neoplasm.
Comparison of molecular changes in cervical intraepithelial neoplasia in HIV-positive and HIV-indeterminate subjects
(ACADEMIC PRESS INC ELSEVIER SCIENCE, 1999) Wistuba, II; Syed, S; Behrens, C; Duong, M; Milchgrub, S; Muller, CY; Jagirdar, J; Gazdar, AF
Objective. HIV infection is associated with an increased incidence of cervical malignancy and its precursor lesions (CIN, cervical intraepithelial neoplasia) compared with the general population. We studied the molecular abnormalities in the development of HIV-associated CIN and compared them with those present in CINs arising in HIV-indeterminate subjects ("sporadic CIN").
Comparison of molecular changes in lung cancers in HIV-positive and HIV-indeterminate subjects
(AMER MEDICAL ASSOC, 1998) Wistuba, II; Behrens, C; Milchgrub, S; Virmani, AK; Jagirdar, J; Thomas, B; Ioachim, HL; Litzky, LA; Brambilla, EM; Minna, JD; Gazdar, AF
Context.-Human immunodeficiency virus (HIV) infection has been associated with an increasing incidence of malignancy, and HIV-infected persons have an increased incidence of primary lung carcinoma compared with the general population,
Deletions of chromosome 3p are frequent and early events in the pathogenesis of uterine cervical carcinoma
(AMER ASSOC CANCER RESEARCH, 1997) Wistuba, II; Montellano, FD; Milchgrub, S; Virmani, AK; Behrens, C; Chen, HL; Ahmadian, M; Nowak, JA; Muller, C; Minna, JD; Gazdar, AF
To study the molecular abnormalities involved in the multistage development of cervical carcinoma (CC), we investigated the presence of oncogenic human papillomavirus (HPV) sequences, loss of heterozygosity (LOH), and microsatellite alterations at several genes/loci at 3p (3p14.2 at the FHIT gene, 3p14.3-21.1, 3p21, and 3p22-24.2), 9p21, RB and P53, and P53 gene point mutations in precisely microdissected archival tissues from 20 CCs and their accompanying precursor lesions (cervical intraepithelial neoplasia, CIN; n = 40) and normal epithelia (n = 20). In all HPV-positive cases (90% of CCs), HPV sequences were detected as the earliest appearing molecular change or simultaneously with other changes. LOH at any 3p region was found in 70% of CCs, and 3p14.2 (FHIT gene/FRA3B fragile site) (56%) and 3p21 (57%) were the most frequent 3p sites of loss. LOH at some 3p region was in the CIN I stage, and the 3p deletions in precursor CIN lesions were smaller than the 3p losses found in the associated invasive CC. LOH at the other regions studied and P53 gene mutations were less frequent and later events. Microsatellite alterations were detected in 35% of CCs, and identical abnormalities were detected in the associated precursor lesions. Although infection with oncogenic HPV strains is the earliest and most frequent molecular event, progressive deletions at one or more 3p regions (particularly at 3p14.2, and 3p21) are also frequent events occurring early in the pathogenesis of CC.
Differential expression of FEZ1/LZTS1 gene in lung cancers and their cell cultures
(AMER ASSOC CANCER RESEARCH, 2002) Toyooka, S; Fukuyama, Y; Wistuba, II; Tockman, MS; Minna, JD; Gazdar, AF
Purpose: The FEZ1/LZTS1 (FEZ1) gene, located on chromosome 8p22 (8p22), was identified recently as a candidate tumor suppressor gene. Because loss of heterozygosity at 8p21-22 is a frequent event in lung cancers, we studied FEZ1 alteration in short-term cultures of resected lung cancer tumors and cell lines.
Distinct K-ras mutation pattern characterizes signet ring cell colorectal carcinoma
(AMER ASSOC CANCER RESEARCH, 2003) Wistuba, II; Behrens, C; Albores Saavedra, J; Delgado, R; Lopez, F; Gazdar, AF
Purpose: Signet ring cell colorectal carcinoma (SRCCC) represents a unique, infrequent, and highly malignant variant of colorectal cancer. To understand the pathogenesis of SRCCC, we investigated its molecular abnormalities and compared them with those of the usual type of colorectal adenocarcinoma.
Gallbladder adenomas have molecular abnormalities different from those present in gallbladder carcinomas
(1999) Wistuba, II; Miquel, JF; Gazdar, AF; Albores-Saavedra, J
Although most gallbladder carcinomas evolve from dysplasia and carcinoma in situ, the role of gallbladder adenomas in the pathogenesis of gallbladder carcinoma is still controversial. A series of molecular changes including loss of heterozygosity (LOH) at 17p (TP53 gene), 13q (RB gene), 18q (DCC gene), and 9p21 (CDKN2a gene) chromosomal regions have been identified in dysplasias, carcinomas in situ, and invasive carcinomas of the gallbladder, whereas mutations in K- and N-ras genes are rare. To determine whether the molecular abnormalities of adenomas are similar to those found in carcinomas, we obtained extracted DNA from precisely microdissected tissue from 16 gallbladder adenomas (14 pyloric and 2 intestinal-type). We determined the presence of mutations in TP53, K- and N-ras genes, and LOH at five chromosomal regions (5q22 APC-MCC region, RE, TP53, DCC and 9p21-CDKN2 alpha). For the TP53 mutation study, single strand conformational polymorphism (SSCP) analysis in exons 4 to 8 were performed. K- and N-ras mutations detection was performed by designed restriction fragment length polymorphism (RFLP) method and sequencing. Only a single LOH (at 5q22) was detected in a gallbladder adenoma of intestinal type. No mutations at the TP53 were detected. Four adenomas (25%) showed K-ras mutations (two in codon 12 and two in codon 61). We conclude that gallbladder adenoma lacks the molecular changes frequently detected in dysplasia, carcinoma in situ, and invasive carcinoma of the gallbladder. Likewise the occurrence of K-ras mutations at codon 12 and 61 in 25% of adenomas strongly suggests that these lesions are not precursors of invasive gallbladder carcinoma. HUM PATHOL 30:21-25. Copyright (C) 1999 by W.B. Saunders Company.
Genome-wide allelotyping analysis reveals multiple sites of allelic loss in gallbladder carcinoma
(AMER ASSOC CANCER RESEARCH, 2001) Wistuba, II; Tang, MY; Maitra, A; Alvarez, H; Troncoso, P; Pimental, F; Gazdar, AF
Although gallbladder carcinoma (GBC) is a highly malignant neoplasm, there is very limited information about the molecular changes involved in its pathogenesis. To identify the chromosomal locations of putative tumor suppressor gene loci Involved in the pathogenesis of GBC, we conducted a genome-wide allelotyping or loss of heterozygosity (LOH) analysis of GBCs. Microdissected tissue from 24 archival GBCs and their matched control DNAs were analyzed for PCR-based LOH using 169 microsatellite markers spanning all nonacrocentric autosomal arms and the X chromosome. The chromosomal arms with the greatest frequencies of LOH (greater than or equal to 60%) were 3p, 6q, 7q, 8p, 9p, 9q, 11q, 12q, 17p, 18q, 19p, 22q, and Xq. The average fractional allele loss index in GBC cases was high (0.43) and frequent breakpoints were detected in gallbladder tumors. Of interest, 21 different regions of frequent LOH (hot spots) defined as greater than or equal to 50% for individual GBC samples were detected in this neoplasm, nearly half of them confined to one microsatellite marker. We conclude that in GBC at least 21 chromosomal regions with frequent allele losses are involved, suggesting that several putative tumor suppressor genes are inactivated in its pathogenesis. Overall, these data provide global estimates of the extent of genetic changes leading to GBC and will be useful for the identification of new tumor suppressor genes and for multiple new markers for translational research.
High resolution chromosome 3p allelotyping of human lung cancer and preneoplastic/preinvasive bronchial epithelium reveals multiple, discontinuous sites of 3p allele loss and three regions of frequent breakpoints
(2000) Wistuba, II; Behrens, C; Virmani, AK; Mele, G; Milchgrub, S; Girard, L; Fondon, JW; Garner, HR; McKay, B; Latif, F; Lerman, MI; Lam, S; Gazdar, AF; Minna, JD
Allele loss involving chromosome arm 3p is one of the most frequent and earliest known genetic events in lung cancer pathogenesis and may affect several potential tumor suppressor gene regions. To Further study the role of chromosome 3p allele loss in the pathogenesis of lung cancer, we performed high resolution toss of heterozygosity (LOH) studies on 97 lung cancer and 54 preneoplastic/preinvasive microdissected respiratory epithelial samples using a panel of 28 3p markers. Allelic losses of 3p were detected in 96% of the lung cancers and in 78% of the preneoplastic/ preinvasive lesions. The allele losses were often multiple and discontinuous, with areas of LOH interspersed with areas of retention of heterozygosity, Most small cell lung carcinomas (91%) and squamous cell carcinomas (95%) demonstrated larger 3p segments of allele loss, whereas most (71%) of the adenocarcinomas and preneoplastic/preinvasive lesions had smaller chromosome areas of 3p allele loss. There was a progressive increase in the frequency and size of 3p allele loss regions with increasing severity of histopathological preneoplastic/preinvasive changes. In analyses of the specific parental allele lost comparing 42 preneoplastic/preinvasive foci with those lost in the lung cancer in the same patient (n = 10), the same parental allele was lost in 88% of 244 comparisons for 28 3p markers (P = 1.2 x 10(-36) for this occurring by chance). This indicates the occurrence of allele-specific loss in these foci similar to that seen in the tumor by a currently unknown mechanism. Analysis of all of the data indicated multiple regions of localized 3p allele loss including telomere-D3S1597, D3S1111-D3S2432, D3S2432-D3S1537, D3S1537, D3S1537-D3S1612, D3S4604/Luca19.1-D3S4622/Luca4.1, D3S4624/Luca2.1, D3S4624/ Luca2.1-D3S1582, D3S1766, D3S1234-D3S1300 (FHIT/FRA3B region centered on D3S1300), D3S1284-D3S1577 (U2020/DUTT1 region centered on D351274), and D3S1511-centromere. A panel of six markers in the 600-kb 3p21.3 deletion region showed loss in 77% of the lung cancers, 70% of normal or preneoplastic/preinvasive lesions associated with lung cancer, and 49% of 47 normal, mildly abnormal, or preneoplastic/preinvasive lesions found in smokers without lung cancer; however, loss was seen in 0% of 18 epithelial samples from seven never smokers. The 600-kh 3p21.3 region and the 3p14.2 (FHIT/FRA3B) and 3p12 (U2020/DUTT1) regions were common, independent sites of breakpoints (retention of heterozygosity by some markers and LOH by other markers in the immediate region), We conclude that 3p allele loss Is nearly universal in lung cancer pathogenesis; involves multiple, discrete, 3p LOH sites that often show a "discontinuous LOH" pattern in individual tumors; occurs in preneoplastic/preinvasive lesions in smokers with and without lung cancer (multiple lesions often Lose the same parental allele); frequently involves breakpoints in at least three very small defined genomic regions; and appears to have allele Loss and breakpoints first occurring in the 600-kb 3p21.3 region. These findings are consistent with previously reported LOH studies in a variety of tumors showing allele loss occurring by mitotic recombination and induced by oxidative damage.
High-resolution chromosome 3p allelotyping of breast carcinomas and precursor lesions demonstrates frequent loss of heterozygosity and a discontinuous pattern of allele loss
(2001) Maitra, A; Wistuba, II; Washington, C; Virmani, AK; Ashfaq, R; Milchgrub, S; Gazdar, AF; Minna, JD
We performed high-resolution allelotyping for loss of heterozygosity (LOH) analysis on microdissected samples from 45 primary breast cancers, 47 mammary preneoplastic epithelial foci, and 18 breast cancer cell Lines, using a panel of 27 polymorphic chromosome 3p markers. Allele loss in some regions of chromosome 3p was detected in 39 of 45 (87%) primary breast tumors. The 3p21.3 region had the highest frequency of LOH (69%), followed by 3p22-24 (61%), 3p21.2-21.3 (58%), 3p25 (48%), 3p14.2 (45%), 3p14.3 (41%), and 3p12 (35%). Analysis of all of the data revealed at least nine discrete intervals showing frequent allele loss: D3S1511-D3S1284 (U2020/DUTT1 region centered on D3S1274 with a homozygous deletion), D3S1300-D3S1234 [fragile histidine triad (FHIT)/FRA3B region centered on D3S1300 with a homozygous deletion], D3S1076-D3S1573, D3S4624/ Luca2.1-D3S4597/P1.5, D3S1478-D3S1029, D3S1029 (with a homozygous deletion), D3S1612-D3S1537, D3S1233-D3S1597, and D3S1597-telomere; it is more than likely that additional localized regions of LOH not examined in this study also exist on chromosome 3p. In multiple cases, there was discontinuous allele loss at several 3p sites in the same tumor. Twenty-one of 47 (45%) preneoplastic lesions demonstrated 3p LOH, including 12 of 13 (92%) ductal carcinoma in situ, 2 of 7 (29%) apocrine metaplasia, and 7 of 25 (28%) usual epithelial hyperplasia. The 3p21.3 region had the highest frequency of LOH in preneoplastic breast epithelium (36%), followed by 3p21.2-21.3 (20%), 3p14.2/FHIT region (11%), 3p25 (10%), and 3p22-24 (5%). In 39 3p loci showing LOH in both the tumor and accompanying preneoplasia, 34 (87%) showed loss of the same parental allele (P = 1.2 x 10(-6), cumulative binomial test). In addition, when 21 preneoplastic samples showing LOH were compared to their accompanying cancers, 67% were clonally related, 20% were potentially clonally related but were divergent, and 13% were clonally unrelated. Overall this demonstrated the high likelihood of clonal relatedness of the preneoplastic foci to the tumors. We conclude that: chromosome 3p allele loss is a common event in breast carcinoma pathogenesis; involves multiple, localized sites that often show discontinuous LOH with intervening markers retaining heterozygosity; and is seen in early preneoplastic stages, which demonstrate clonal relatedness to the invasive cancer.
Molecular abnormalities associated with endocrine tumors of the uterine cervix
(ACADEMIC PRESS INC ELSEVIER SCIENCE, 1999) Wistuba, II; Thomas, B; Behrens, C; Onuki, N; Lindberg, G; Albores Saavedra, J; Gazdar, AF
Objective. We studied the molecular abnormalities involved in the pathogenesis of endocrine tumors of the uterine cervix.
Molecular changes in second primary lung and breast cancers after therapy for Hodgkin's disease
(2000) Behrens, C; Travis, LB; Wistuba, II; Davis, S; Maitra, A; Clarke, EA; Lynch, CF; Glimelius, B; Wiklund, T; Tarone, R; Gazdar, AF
The risk of lung and breast cancer is significantly increased after therapy for Hodgkin's disease (HD), but there are few data that describe the molecular profiles of these tumors. We investigated the genetic abnormalities in second primary lung (n = 19) and breast cancers (n = 19) that follow therapy for HD ("post-HD cancers") and compared these with changes observed in corresponding tumor types (57 lung and 20 breast cancers) arising in the general population ("sporadic cancers"). DNA obtained from archival tissues was examined using PCR-based analyses for loss of heterozygosity and microsatellite alterations (MAs) at several chromosomal regions, TP53 and K-uas gene mutations, and frameshift mutations at minisatellite sequences at the coding regions of several genes (TGF-beta RII, IGFIIR, BAX, hMSH6, and hMSH3). The occurrence of loss of heterozygosity at all chromosomal regions taken together and frequencies at most individual areas were similar for the post-HD and sporadic cancers for both lung and breast sites, The overall frequency of MAs in the post-HD tumors was substantially greater (lung, 2.4-fold, P = 0.004; breast, 4.2-fold, P = 0.16) than that in the respective sporadic cancers. No differences in the pattern of TP53 and K-ras mutations were detected between post-HD and sporadic cancers. No mutations were detected at the minisatellite sequences examined. MAs, which reflect widespread genomic instability, occur at greatly increased frequency in post-HD lung and breast cancers. Although the mechanisms underlying the development of increased MAs are unknown, they have been associated with immunosuppression and radiation exposure. Future research should address the role that MAs, as well as other influences, may play in the development of neoplasias that occur after therapy for HD.
Molecular changes in the bronchial epithelium of patients with small cell lung cancer
(AMER ASSOC CANCER RESEARCH, 2000) Wistuba, II; Berry, J; Behrens, C; Maitra, A; Shivapurkar, N; Milchgrub, S; Mackay, B; Minna, JD; Gazdar, AF
To better understand the pathways involved in the pathogenesis of small cell lung carcinoma (SCLC), we compared the patterns of molecular changes present in these tumors and their accompanying bronchial epithelium with those present in the other two major types of lung cancer [squamous cell carcinoma (SQC) and adenocarcinoma (ADC)I, We obtained DNA from 68 microdissected invasive lung tumors (22 SCLCs, 21 ADCs, and, 25 SQCs) and 119 noncontiguous foci of histologically normal or hyperplastic epithelia from 10 tumors of each histological type. We determined loss of heterozygosity and microsatellite alterations at 12 chromosomal regions frequently deleted in lung cancers using 19 polymorphic microsatellite markers. Our major findings are as follows: (a) the mean index of allelic loss in SCLC (0.85) and SQC (0.71) tumors was higher than that in ADC (0.39) tumors; (b) although there was considerable overlap, each tumor type had a characteristic pattern of allelic loss; (c) most samples of bronchial epithelium accompanying SCLC (90%) had allelic loss at one or more loci compared with samples accompanying SQC (54%) or ADC (10%); (d) the mean index of allelic loss was much higher in bronchial epithelial samples from SCLC (0.27) than in those from SQC (0.08) or ADC (0.01); and (e) although the mean indices of microsatellite alterations in the tumor types were similar, the bronchial epithelial samples accompanying SCLC had a 10-fold higher mean index (0.063) than those accompanying SQC (0.006) or ADC (0,006), Our findings indicate that extensive genetic damage in the accompanying normal and hyperplastic bronchial epithelium is characteristic of SCLC tumors and suggest major differences in the pathogenesis of the three major lung cancer types.
Molecular damage in the bronchial epithelium of current and former smokers
(1997) Wistuba, II; Lam, S; Behrens, C; Virmani, AK; Fong, KM; LeRiche, J; Samet, JM; Srivastava, S; Minna, JD; Gazdar, AF
Background: Most lung cancers are attributed to smoking, These cancers have been associated with multiple genetic alterations and with the presence of preneoplastic bronchial lesions, In view of such associations, we evaluated the status of specific chromosomal loci in histologically normal and abnormal bronchial biopsy specimens from current and former smokers and specimens from nonsmokers, Methods: Multiple biopsy specimens were obtained from 18 current smokers, 24 former smokers, and 21 nonsmokers, Polymerase chain reaction-based assays involving 15 polymorphic microsatellite DNA markers were used to examine eight chromosomal regions for genetic changes (loss of heterozygosity [LOH] and microsatellite alterations), Results: LOH and microsatellite alterations were observed in biopsy specimens from both current and former smokers, but no statistically significant differences were observed between the two groups. Among individuals with a history of smoking, 86% demonstrated LOH in one or more biopsy specimens, and 24% showed LOH in all biopsy specimens, About half of the histologically normal specimens from smokers showed LOH, but the frequency of LOH and the severity of histologic change did not correspond until the carcinoma in situ stage, A subset of biopsy specimens from smokers that exhibited either normal or preneoplastic histology showed LOH at multiple chromosomal sites, a phenomenon frequently observed in carcinoma in situ and invasive cancer, LOH on chromosomes 3p and 9p was more frequent than LOH on chromosomes 5q, 17p (17p13; TP53 gene), and 13q (13q14; retinoblastoma gene), Microsatellite alterations were detected in 64% of the smokers, No genetic alterations were detected in nonsmokers, Conclusions: Genetic changes similar to those found in lung cancers can be detected in the nonmalignant bronchial epithelium of current and former smokers and may persist for many years after smoking cessation.
Sequential molecular abnormalities are involved in the multistage development of squamous cell lung carcinoma
(1999) Wistuba, II; Behrens, C; Milchgrub, S; Bryant, D; Hung, J; Minna, JD; Gazdar, AF
To understand the molecular pathways involved in the pathogenesis of squamous cell lung carcinoma, we obtained DNA from 94 microdissected foci from 12 archival surgically resected tumors including histologically normal epithelium (n = 13), preneoplastic lesions (n = 54), carcinoma is situ (CIS) (n = 15) and invasive tumors (n = 12). We determined loss of heterozygosity (LOH) at 10 chromosomal regions (3p12, 3p14.2, 3p14.1-21.3, 3p21, 3p22-24, 3p25, 5q22, 9p21, 13q14 RE, and 17p13 TP53) frequently deleted in lung cancer, using 31 polymorphic microsatellite markers, including 24 that spanned the entire 3p arm. Our major findings are as follows: (1) Thirty one percent of histologically normal epithelium and 42% of mildly abnormal (hyperplasia/metaplasia) specimens had clones of cells with allelic loss at one or more regions; (2) There was a progressive increase of the overall LOH frequency within clones with increasing severity of histopathological changes; (3) The earliest and most frequent regions of allelic loss occurred at 3p21, 3p22-24, 3p25 and 9p21; (4) The size of the 3p deletions increased with progressive histologic changes; (5) TP53 allelic loss was present in many histologically advanced lesions (dysplasia and CIS); (6) Analyses of 58 normal and non-invasive foci having any molecular abnormality, indicated that 30 probably arose as independent clonal events, while 28 were potentially of the same clonal origin as the corresponding tumor; (7) Nevertheless, when the allelic losses in the 30 clonally independent lesions and their clonally unrelated tumors were compared the same parental allele was lost in 113 of 125 (90%) of comparisons. The mechanism by which this phenomenon (known as allele specific mutations) occurs is unknown; (8) Four patterns of allelic loss in clones were found. Histologically normal or mildly abnormal foci had a negative pattern (no allelic loss) or early pattern of loss while all foci of CIS and invasive tumor had an advanced pattern. However dysplasias demonstrated the entire spectrum of allelic loss patterns, and were the only histologic category having the intermediate pattern. Our findings indicate that multiple, sequentially occurring allele specific molecular changes commence in widely dispersed, apparently clonally independent foci, early in the multistage pathogenesis of squamous cell carcinomas of the lung.
Smoking molecular damage in bronchial epithelium
(2002) Wistuba, II; Mao, L; Gazdar, AF
Our understanding of the molecular pathology of lung cancer is advancing rapidly with several specific genes and chromosomal regions being identified. Lung cancer appears to require many mutations in both dominant and recessive oncogenes to possess malignant phenotypes. Several genetic and epigenetic changes are common to all lung cancer histologic types, while others appear to be cell type specific. However, specific roles of the genes undergoing mutations and the order of cumulative molecular changes that lead to the development of each lung tumor histologic type remain to be fully elucidated. Recent findings of molecular abnormalities in normal appearing and preneoplastic bronchial epithelium from patients with lung cancer and chronic smokers suggest that genetic changes may serve as biomarkers for early diagnosis, risk assessment and monitoring response to chemoprevention.
Two identical triplet sisters carrying a germline BRCAI gene mutation acquire very similar breast cancer somatic mutations at multiple other sites throughout the genome
(WILEY, 2000) Wistuba, II; Tomlinson, GE; Behrens, C; Virmani, A; Geradts, J; Blum, JL; Minna, JD; Gazdar, AF
Monozygotic twins, each of whom has breast cancer, offer a natural study population for gene-environmental interactions as causation of cancer, because they are genetically identical. If heritable factors play a large role in the origin of a neoplasm, disease concordance should be significant in monozygotic twins. Two monozygotic triplet sisters carrying a germline BRCA1 gene mutation (5382insC) who both developed breast cancer at early ages were studied for loss of heterozygosity (LOH) in their microdissected, paraffin-embedded tumors along with control blood and stromal breast tissue at 19 chromosomal arms using 161 microsatellite markers. Microdissected areas of normal lobular and ductal epithelium and ductal in situ carcinoma were also studied for LOH using a subset of microsatellite markers. The mother's DNA (extracted from peripheral blood lymphocytes) was analyzed to determine the parental allele under LOH in each case. Both tumors demonstrated similar histologic features suggestive of a secretory variant of ductal carcinoma. The tumors from both sisters had similar overall LOH frequency expressed by the fractional allelic loss (FAL) indices (0.56 vs, 0.60) and demonstrated concordance for loss or retention at 82 of 97 informative markers (85% correlation). In addition, detailed mapping analysis of several chromosomal arms revealed that identical breakpoints were detected in both tumors at several chromosome regions. Finally, in both sisters' tumors, when a chromosome exhibited allelic loss, all of the markers exhibited LOH of the same parental allele even when there were intervening regions of retention of heterozygosity, In contrast, 17 archival sporadic breast carcinomas demonstrated a wide range of FAL indexes and highly individual patterns of LOH. Our findings support the hypothesis that inherited factors play a role in the development of the multiple somatic deletions occurring in breast carcinomas. Whether one of these factors is the mutant BRCA1 allele or some other gene(s) remains to be determined. (C) 2000 Wiley-Liss, Inc.

Browsing by Author "Gazdar, AF"

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