An allelotype of papillary thyroid cancer

Although papillary carcinoma accounts for approximately 70% of all thyroid cancers, preliminary studies of allelic loss have thus far not identified any areas of chomosomal deletion. We evaluated 30 papillary thyroid carcinomas for chromosomal loss/allelic imbalance by testing at least 2 microsatellite markers from every autosomal arm. Fifteen of the 30 tumors tested exhibited loss of heterozygosity/allelic imbalance (LOH/AI) at one or more loci. Chromosomal arms with frequent LOH/AI included 4q, 5p, 7p and 11p. An average of 1.1 chromosomal arms displayed LOH/AI in each individual tumor. Therefore, 4q, 5p, 7p and, to a lesser extent, 11p display significant LOH/AI in papillary thyroid cancer, which indicates the presence of putative tumor-suppressor gene loci at these chromosomal arms. © 1996 Wiley-Liss, Inc.     

Extended genetic alterations in a patient with pulmonary sarcoidosis, a benign disease

BACKGROUND: Genetic alterations at the microsatellite level have been detected in various human malignant tissues, but have also been found in chronically inflamed tissues. Sarcoidosis is a benign disease of unknown etiology characterized by chronic inflammation, which may be associated with an increased incidence of developing malignancy. METHODS: We examined the microsatellite alterations in a sputum cytological specimen of a patient with sarcoidosis. The DNA electrophoretic pattern of sputum was compared with that of the peripheral blood. Thirty-two microsatellite markers located at chromosomes 2p, 3p, 8p, 9p, 9q, 17p, 17q were used to reveal genetic alterations. RESULTS: Loss of heterozygosity (LOH) was detected in eleven markers in loci 2p, 9p, 9q and 17q. LOH was observed in all four markers spanning the chromosomal arm 17q11.2-q21, suggesting a potential chromosomal deletion. CONCLUSION: The observation of LOH in all four markers spanning the chromosomal arm 17q11.2-q21 may suggest a potential for malignancy development in this patient, or may be linked to the aetiopathogenesis of sarcoidosis. Further microsatellite fine mapping and clinical follow up of this patient are needed to clarify this.     

Occurrence of chromosome 9 and p53 alterations in multifocal dysplasia and carcinoma in situ of human urinary bladder

To define the genetic changes of flat urothelial lesions, carcinoma in situ (CIS) and moderate dysplasias (DII) were investigated for alterations in the two chromosomal regions most frequently involved in bladder cancer. Overall, 33 CIS and 16 DII from 21 patients were used to microdissect urothelium. Dual color fluorescence in situ hybridization (FISH) using gene locus probes of 9q22 (FACC), 9p21 (CDK), 17p13 (p53), and related centromeric probes was applied on interphase nuclei. In parallel, preamplified DNA of these samples was used for loss of heterozygosity (LOH) analyses with eight microsatellite markers on chromosomes 9p, 9q and 17p, and for sequencing of exons 5-9 of p53. Data indicated nearly identical deletion frequencies for chromosomes 9 and 17 for CIS (chromosome 9, 86%; p53, 84%). DII showed a lower deletion rate in comparison with CIS (chromosome 9, 75%; p53, 53%). A very high correlation between the results of FISH and LOH analyses was found. p53 mutations were detected in 12 of 15 patients (CIS, 72%; DII, 67%). In three of 16 patients with multifocal tumors, oligoclonal lesions were identified by LOH analyses, a finding further supported by sequencing of p53, by which two different p53 deletions were detected in two cases. In conclusion, data from microdissected flat urothelial lesions indicate that chromosome 9 deletions cannot be regarded as indicators of papillary growth, because they are found frequently in both types of flat lesions of the urothelium: those associated with papillary tumors and those that are not. The similar distribution and lower amount of genetic changes in DII render DII a possible precursor lesion of CIS.     

Loss of heterozygosity at 8p, 9p and 17q in laryngeal cytological specimens

The activation of oncogenes and the inactivation of tumour suppressor genes play a critical role in laryngeal tumorigenesis. Recent investigations revealed that 8p, 9p and 17q arms of human chromosomes harbour tumour suppressor genes (TSGs) such as p16 and BRCA1 with an important role in the multistage carcinogenesis of the larynx. In order to investigate the implication of these novel TSGs in the development of laryngeal neoplasia we performed a loss of heterozygosity (LOH) analysis using a bank of 15 polymorphic microsatellite markers (4 at 8p21, 7 at 9p21 arm and 4 at 17q arm surrounding the BRCA1 region) in a series of 32 cytological specimens (19 squamous cell carcinoma, 13 benign lesions of the larynx). Both benign and malignant specimens exhibited genetic alterations with at least one microsatellite marker. Fifteen (47%) out of the 32 specimens exhibited LOH at 8p21, 25/32 (78%) showed LOH at 9p21 and 18/32 (56%) displayed LOH at 17q21. Genetic alterations were detected in both benign and malignant lesions for all the loci tested suggesting an important role of these regions in the development of laryngeal neoplasia. This is the first report of detection of microsatellite alterations not only in solid tumours of the larynx but in laryngeal cytological specimens, suggesting that microsatellite analysis may be a useful tool in the primary diagnosis of the disease.     

Partial allelotype of schistosomiasis-associated bladder cancer

In Egypt and other regions of the Middle East where the trematode Schistosoma haematobium is endemic, bladder cancer is the most common adult cancer. Unlike bladder cancers in Western countries, which are predominantly transitional-cell carcinoma (TCC), these schistosomiasis-associated bladder cancers are predominantly squamous-cell carcinoma (SCC). Our aim was to assess a large series of schistosomiasis-associated bladder tumours for genetic alterations commonly found in TCC in the United Kingdom and the United States. We have carried out a partial allelotype of 70 tumours from patients with schistosomiasis. LOH was found on all chromosome arms studied (3p, 4p, 4q, 8p, 9p, 9q, 11p, 11q, 13q, 14q, 17p, 18q). The most frequent regions of LOH were 9p (65%), 17p (58%), 3p (40%), 9q (39%) and 8p (37%). LOH on 17p, where the TP53 gene is located, was more common in Egyptian TCC than in SCC. Similarly, 8p LOH was more common in TCC than SCC. The most striking difference between this group of tumours and TCCs from the United Kingdom and the United States was the high frequency of 9p LOH in the region of the CDKN2 gene (65%) and the relatively low frequency of 9q LOH (39%); 15 of 43 tumours with LOH of at least one marker on chromosome 9 showed LOH of 9p only. This suggests that a 9p gene, possibly CDKN2, may contribute to the development of the majority of schistosomiasis-associated bladder tumours but that genes on 9q play a much less important role.     

Evidence for two candidate tumour suppressor loci on chromosome 9q in transitional cell carcinoma (TCC) of the bladder but no homozygous deletions in bladder tumour cell lines.

The most frequent genetic alterations in transitional cell carcinoma (TCC) of the bladder involve loss of heterozygosity (LOH) on chromosome 9p and 9q. The LOH on chromosome 9p most likely targets the CDKN2 locus, which is inactivated in about 50% of TCCs. Candidate genes that are the target for LOH on chromosome 9q have yet to be identified. To narrow the localization of one or more putative tumour suppressor genes on this chromosome that play a role in TCC of the bladder, we examined 59 tumours with a panel of microsatellite markers along the chromosome. LOH was observed in 26 (44%) tumours. We present evidence for two different loci on the long arm of chromosome 9 where potential tumour suppressor genes are expected. These loci are delineated by interstitial deletions in two bladder tumours. Our results confirm the results of others and contribute to a further reduction of the size of these regions, which we called TCC1 and TCC2. These regions were examined for homozygous deletions with EST and STS markers. No homozygous deletions were observed in 17 different bladder tumour cell lines.     

Destabilization of chromosome 9 in transitional cell carcinoma of the urinary bladder.

The most frequent genetic alteration in transitional cell carcinoma of the urinary bladder (TCC) is loss of chromosome 9 which targets CDKN2A on 9p. The targets on 9q are not confirmed. Here, 81 advanced TCC specimens were investigated for loss of heterozygosity (LOH) and homozygous deletions (HD) on chromosome 9q using multiplex analysis of microsatellite markers. 41/81 tumours (51%) showed LOH on 9q, with LOH at all markers in 33 cases. Eight partial losses involved three regions in 9q12, 9q22.3, and 9q33- 9q34. No mutations were identified in the candidate tumour suppressor gene DBCCR1 in three tumours showing restricted LOH at 9q32-33. 22% of the specimens had HD at CDKN2A, but no HD was found on 9q. Two tumours had lost 9p only and five 9q only. 9q LOH was not related to tumour grade or stage and present or absent with equal frequency in recurrent TCC. LOH on 9q correlated with the extent of genome-wide hypomethylation (P < 0.0001) which extended into satellite sequences located in 9q12 juxtacentromeric heterochromatin. While the high frequency of chromosome 9q loss in TCC may reflect destabilization of the chromosome related to hypomethylation of repetitive DNA, the data are compatible with the existence of tumour suppressor genes on this chromosome arm.     

Human bladder cancers and normal bladder mucosa present the same hot spot of heterozygous chromosome-9 deletion

Loss of heterozygosity (LOH) on chromosome 9 is the most frequent genetic alteration in bladder cancer identified to date, suggesting the presence of key gene(s) for this pathology. In this study, we examined 44 bladder tumors and 21 normal bladder samples for LOH on both arms of chromosome 9. Sixteen microsatellite markers, 12 on the short arm (encompassing 9p21-22) and 4 on the long arm (encompassing 9q33-34), were chosen for their highly frequent alterations in bladder cancer. LOH for at least one marker was identified in 42 tumor samples (95.5%), and 14 tumors (32%) displayed LOH for all informative tested markers. Detailed analysis showed that 2 markers on chromosome 9p (D9S157 and D9S156) had the highest frequencies of allelic loss (about 70%), independent of tumor grade and stage. The same study was performed on the 21 normal bladder mucosa samples: 50% of informative cases presented a single specific LOH at the D9S156 locus. Normal samples showing LOH at this locus were therefore screened with 3 novel microsatellite markers in the 810-kb region incorporating D9S156. Using this marker, we found no further heterozygous loss in this region. This result allows different interpretations of the D9S156 loss in normal bladder mucosa, and suggests that D9S156 may be more an indicator of bladder epithelium impairment than a tumor-initiation marker. Similarly, this unexpected result calls in question the interpretation of LOH studies. Int. J. Cancer 77:821–824, 1998.© 1998 Wiley-Liss, Inc.     

Laser capture microdissection analysis reveals frequent allelic losses in papillary urothelial neoplasm of low malignant potential of the urinary bladder

BACKGROUND: In the 1999 World Health Organization classification system, papillary tumors of the urinary bladder were classified as papilloma, papillary urothelial neoplasm of low malignant potential (PUNLMP), and as Grade 1, Grade 2, and Grade 3 urothelial carcinoma. The biologic potential of PUNLMP of the urinary bladder is controversial. To the authors' knowledge, information regarding the genetic changes of PUNLMP tumors of the bladder is limited. METHODS: The authors examined loss of heterogygosity (LOH) at 5 polymorphic microsatellite markers on chromosome 9q32-33 (D9S177), 9p22 (IFNA), 17p13.1 (TP53), 12q14-24 (D12S1051), and 3p25-26 (D3S3050) from 26 patients who were diagnosed with PUNLMP tumors of the urinary bladder. Tumors were microdissected from sections prepared from formalin-fixed, paraffin-processed tissue specimens using laser capture microdissection. RESULTS: LOH was found in 21 of 26 (81%) patients with PUNLMP. The rate of LOH was 41% with D9S177, 32% with IFNA, 29% with TP53, 26% with D12S1051, and 44% with D3S3050. Allelic loss of multiple chromosome loci was often present in patients with PUNLMP tumors. CONCLUSIONS: Genetic changes that commonly occur in advanced bladder carcinoma (> or = pT2) are frequently found in PUNLMP of the urinary bladder.     

Loss of heterozygosity analysis on chromosome 5p defines 5p13-12 as the critical region involved in tumor progression of bladder carcinomas

We have previously observed loss of heterozygosity (LOH) at a single locus (del-27) on human chromosome 5p13-12 to correlate with bladder tumor progression. In this study, we examined 33 bladder tumors for their pattern of allelic loss on chromosome 5p using 7 microsatellite markers. In 14 of 15 bladder tumors with LOH at locus del-27, allelic loss was confined to chromosomal region 5p13-12. This region included the microsatellite marker D5S2025 that showed LOH in 5 of 11 (45%) informative cases with LOH at del-27. This suggests that D5S2025 and del-27 are located within a single critical region of LOH on 5p13-12 harboring a tumor suppressor gene involved in bladder tumor progression. Recurrent LOH at other loci was observed at microsatellite markers located at 5p15. However, these losses appeared to be independent of LOH at 5p13-12 and occurred predominantly in poorly differentiated (G3) and advanced (T3-T4) tumors.     

Loss of heterozygosity and microsatellite instability in hepatocellular carcinoma in Taiwan.

Elucidation of the basic genetic changes of human hepatocellular carcinoma is important for the understanding and treatment of this cancer. We used microsatellite polymorphism markers to study 30 cases of hepatocellular carcinoma (34 tumours) on all human chromosomes. DNA from 34 pairs of hepatocellular carcinomas and corresponding non-tumour parts was prepared. Loss of heterozygosity (LOH) and microsatellite instability on 23 chromosomes were investigated by 231 sets of microsatellite markers. More than 20% LOH was shown for loci on 16q (47.1%), 13q (32.4%), 17p (32.4%), 5q (26.5%), 11p (23.5%) and 9p (20.6%). The commonly affected regions were mapped to 16q12.1, 16q12.2, 16q24, 13q12.1-32, 17p13, 5q32, 5q34, 5q3, 11p15, 11q23-24 and 9p21. Hepatitis B virus carriers had a significantly higher frequency of LOH on chromosomes 5q, 11p and 16q. Furthermore, larger tumour size tended to have higher frequency of LOH at D16S409 locus (16q12.1). Microsatellte instability was only found in 12 of 231 markers and the frequency is very low. These data suggest that the chromosomes 16q, 13q, 17p, 5q, 11p and 9p might participate in hepatocarcinogenesis. However, microsatellite instability might play little role in the development of this cancer in Taiwan.     

Fractional allele loss indicates distinct genetic populations in the development of squamous cell carcinoma of the head and neck (SCCHN)

Loss of heterozygosity (LOH) had been widely used to assess genetic instability in tumours and a high LOH on chromosome arms 3p, 9p and 17p has been considered to be a common event in squamous cell carcinoma of the head and neck (SCCHN). We have investigated LOH in 52 SCCHN using a range of microsatellite markers. LOH was observed in 69% of individuals on 17p using seven markers, in 64% of individuals on 3p using 17 markers and in 61% of individuals on 9p using 11 markers. Fractional allele loss (FAL) has been calculated for each tumour (FAL is the number of chromosomal arms showing LOH divided by the number of informative chromosomal arms) and a median FAL value of 0.25 was obtained in the 52 SCCHN studied. The LOH data were examined on the basis of FAL scores: low FAL (LFAL), 0.00-0.19; medium FAL (MFAL), 0.20-0.32; high FAL (HFAL), 0.33-0.88. HFAL tumours demonstrated a significantly higher LOH on chromosome arms 3p, 9p and 17p, with 94% LOH on 3p, 94% on 9p and 100% on 17p compared with LFAL tumours. Six of the 16 patients in the LFAL group were found to have no LOH on 3p, 9p or 17p and of these four had LOH at other sites, on chromosomes 2p25-p24, 5q21-22, 7pter-p22, 8q13-q22.1, 11q23.3, 13q32, 17q, 18p11.21, 18q21.31 and 19q12-q13.1. These results indicate that LFAL patients form a subset of SCCHN tumours with distinct molecular initiating events which may represent a discrete genetic population.     

Genome-wide allelotyping analysis reveals multiple sites of allelic loss in gallbladder carcinoma

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 (> or = 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 > or = 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.     

Loss of heterozygosity occurs predominantly, but not exclusively, in the epithelial compartment of pleomorphic adenoma

Pleomorphic adenoma (PA), being the most common benign tumor of the salivary glands, is composed of epithelial and mesenchymal compartments. In this study, we analyzed 19 microsatellite markers from chromosomal arms 6q, 8q, 9p, 12q, and 17p in 31 PAs and 3 carcinoma ex pleomorphic adenomas (CXPAs) as well as 11 other non-PA-related carcinomas of the salivary gland for comparison. In our analysis, we differentiated between epithelial and mesenchymal tissues. Loss of heterozygosity (LOH) in PAs was most often found in 8q (32%) and 12q (29%). Two of the three CXPAs displayed allelic loss at all chromosomal arms investigated, whereas the results of the non-PA-related carcinomas were rather heterogeneous. LOH could not only be detected in the epithelial, but also in the mesenchymal, compartments of a subset of PAs, especially at chromosomal arm 8q. Concerning the CXPAs, we were able to demonstrate allelic losses not only in the malignant epithelial compartment, but also in the residual adenoma parts. Our data give further evidence that alterations in 8q may be an early event in PA tumorigenesis, whereas LOH in 12q may characterize cells with the potential to transform in CXPAs.     

Microsatellite alterations on chromosome 9 in chewing tobacco-induced oral squamous cell carcinomas from India

Genomic instability as reflected by microsatellite alterations in specific target regions is an important characteristic of oral squamous cell carcinoma (OSCC). Microsatellite instability (MSI) and loss of heterozygosity (LOH) on chromosome 9 has been reported as an early event in oral cancers, primarily from patients in the USA and UK. Hence, we examined 77 primary oral cancer tissues and corresponding peripheral blood cell (PBC) DNA from Indian oral cancer patients for LOH and MSI, using a panel of 11 microsatellite markers spanning chromosome 9 on p and q arms. The patients were long-time (minimum 10 years) tobacco chewers. The matched DNA samples were amplified by polymerase chain reaction, resolved on a denaturing polyacrylamide gel and visualized by silver staining. An overall of 62% (48/77 cases) of the patients demonstrated microsatellite alterations including 27% MSI and 52% LOH, although at individual loci MSI was observed in 3-8% patients and LOH in the informative cases ranged from 4 to 41%. A majority of the alterations occurred on the p arm at 9p21-23, with 85% (41/48 cases) genetic alterations concentrated between markers D9S157 and D9S161. Multiple alterations were seen in 56% (27/48) of the affected cases with 17 patients showing microsatellite alterations in three to eight loci. Our data show the incidence of genetic alterations primarily in the chromosomal region 9p21-23, and may be indicative of involvement of p16 (CDKN2) tumor suppressor gene on chromosome 9p21, in a subset of chewing tobacco-induced oral cancers.     

Chromosome 9 deletions are more frequent than FGFR3 mutations in flat urothelial hyperplasias of the bladder

Flat urothelial hyperplasias (FUHs) in patients with papillary bladder tumours frequently show deletions of chromosome 9, suggesting that FUH could be the first neoplastic step in the development of papillary bladder cancer. FGFR3 mutations are frequent in non-invasive papillary tumours with low risk of progression. Our aim was to investigate the frequency of FGFR3 mutations and deletions of chromosomes 9p/q and 8p/q in FUH. Thirty FUH and 9 simultaneous or consecutive tumours were detected by 5-ALA-based photodynamic cystoscopy. DNA was isolated from frozen sections and whole genome amplification was done by I-PEP-PCR, followed by LOH analysis on chromosomes 8p/q and 9p/q. FGFR3 mutations were detected by SNaPshot analysis. LOH analysis on FUH revealed deletions at 9p/q (11/30, 37%) and 8p/q (3/30, 10%). FGFR3 mutations were found in 7/30 FUH (23%). Only 2 FUH showed an FGFR3 mutation without deletions of chromosome 9. In contrast, 6 FUH revealed chromosome 9 deletions but wild type FGFR3 (p = 0.03). These results suggest that chromosome 9 deletions are the earliest genetic alterations in bladder cancer. The detection of FGFR3 mutations in FUH further supports the role of this lesion as precursor of papillary bladder cancer.     

河南食管癌高发区居民食管癌变过程中微卫星LOH的特征

目的微卫星（microsatellite）是广泛分布于生物基因组中的DNA重复序列，与许多重要基因紧密连锁。本研究旨在探讨食管癌变多阶段演进过程中微卫星DNA杂合缺失（loss of heterozygosity，LOH）的特征及其意义。方法采用微卫星DNA多态分析法，选取染色体3p、5q、6p、9p、13q、17p、17q和18q的15个多态微卫星位点，对32例食管癌前病变和癌组织进行LOH分析。结果食管各级癌前病变组织和癌组织均出现不同程度的微卫星DNALOH，其频率随病变程度加重而明显升高（除D9S1752位点外，P均〈0．05）；其中D9S171、D13S260和TP53位点在癌阶段，LOH频率均超过60％。各级癌前病变组织和癌组织中发生LOH的位点不尽相同，同一个体从基底细胞过度增生→间变→原位癌→鳞状细胞癌，均发生LOH的位点是：D3S1234和TP53。结论基因水平的改变发生在食管癌变的早期阶段，随病变程度加重，基因组不稳定性增强，可能是导致食管癌前病变持续向癌的方向发展的重要机制之一。     

Ductal carcinoma in situ of the breast with different histopathological grades and corresponding new breast tumour events: analysis of loss of heterozygosity

To compare chromosomal alterations in ductal carcinoma in situ (DCIS) of different histopathological grades and to study aberrations between primary DCIS and corresponding ipsi- or contralateral new in situ or invasive tumours, a study was undertaken of the pattern of loss of heterozygosity (LOH) at chromosomal regions in which LOH has previously been described in invasive breast cancer. LOH was analysed using 19 microsatellite markers located on chromosomes 3p, 6q, 8p, 8q, 9p, 11p, 11q, 16q, 17p, and 17q in 30 women with a primary DCIS. Eleven women with DCIS of grade 1 and 19 with grade 3 according to the EORTC classification system were included. In six patients LOH was also analysed in a subsequent new breast cancer. Fractional allelic loss (FAL, the ratio of chromosomal arms where allelic loss was detected divided by the total number of chromosomal arms with informative markers) was statistically significantly higher in grade 1 DCIS compared with grade 3 (p=0.02) for the 19 loci, indicating that the amount of allelic loss does not correlate with increasing aggressiveness of the studied tumours. Also observed was a complete heterogeneity of LOH in the primary DCIS and their corresponding new events, suggesting that these events probably developed from genetically divergent clones.     

Assessment of microsatellite instability in urine in the detection of transitional-cell carcinoma of the bladder

Loss of heterozygosity (LOH) and alterations in microsatellite DNA markers have been reported in bladder-cancer tumors. We have studied, in a blinded fashion, using PCR-based microsatellite analysis, genetic alterations of cells exfoliated in urine of 59 Caucasian patients and control patients; 31 with initially confirmed bladder transitional-cell carcinoma (TCC), 17 with signs and symptoms suggestive of bladder cancer, 6 control patients who underwent renal transplantation, and 5 control patients with urolithiasis. Microsatellite analysis of cells exfoliated in the urine allowed the diagnosis of 83% (10/12) of patients with bladder TCC recurrence confirmed by cystoscopy, while 100% of patients followed up for transitional-cell carcinoma of the bladder for up to 12 months without evidence of tumor recurrence upon routine cystoscopy showed no microsatellite alterations. None of the patients without neoplasia (negative controls) had any microsatellite alterations, whereas all patients who underwent renal transplantation had additional new alleles corresponding to contamination with donor's renal and urothelial cells (positive controls). No control patients had any evidence of transitional-cell carcinoma by cystoscopy. Our results provide objective evidence that non-invasive molecular detection of bladder TCC by microsatellite analysis is reproducible with a sensitivity of 83% and a specificity of 100% in Caucasian patients. This non-invasive procedure represents a potential clinical tool for the detection and the screening of bladder TCC. Int. J. Cancer (Pred. Oncol.) 79:629–633, 1998. © 1998 Wiley-Liss, Inc.     

Clustering of minimal deleted regions reveals distinct genetic pathways of human hepatocellular carcinoma

Systematic scan and statistical analysis of loss of heterozygosity (LOH) has been widely used to define chromosomal aberrations in various cancers for cloning of tumor suppressor genes and for development of prognostic markers. However, the establishment of novel strategies is needed, so that the nonrandom but heterogeneous chromosomal aberration data could provide significant insights into our understanding of molecular pathogenesis of cancers. After comprehensive allelotyping of recurrent allelic losses with 441 highly informative microsatellite markers and overlapping LOH regions on human hepatocellular carcinoma (HCC) chromosomes, 33 minimal deleted regions (MDRs) were revealed. Five and 15 of the 33 MDRs have physical intervals in less than 5 and 10 Mb, respectively, with the smallest MDR9p1 of 2.2 Mb located at 9p21.3-p21.2. Statistical and Kaplan-Meier survival analysis revealed a significant association between the loss of MDR15q1 (15q21.1-q22.2) and the HCC patient survival (adjusted P = 0.033). After cluster analysis of 33 MDRs that represented LOH profiles of each HCC tissue based on clinicopathological features and p53 mutations, two major genetic pathways, low-stage and advanced-stage HCC, were uncovered based on high concordance of MDR clusters. We propose that the definition of genome-wide MDRs on the cancer genome not only narrows down the location of existing tumor suppressor genes to facilitate positional candidate cloning and develop potential prognostic markers after statistical association of MDRs with clinicopathological features but also dissects genetic interactions and pathways of chromosomal aberrations in tumorigenesis.