Loss of heterozygosity at chromosome 9p21 is a frequent finding in enteropathy-type T-cell lymphoma

Enteropathy-type T-cell lymphoma (ETL) and ulcerative jejunitis (UJ) are rare disorders often occurring in patients with coeliac disease. The genetic events associated with the accumulation of intraepithelial lymphocytes in coeliac disease and tumour development are largely unknown. Deletions at chromosome 9p21, which harbours the tumour suppressor genes p14/ARF, p15/INK4b, and p16/INK4a, and 17p13, where p53 is located, are associated with the development and progression of lymphomas. To examine whether deletions at 9p21 and 17p13 play a role in ETL, 22 cases of ETL and seven cases of UJ were screened for loss of heterozygosity (LOH) by tissue microdissection and polymerase chain reaction (PCR) analysis for microsatellite markers. Furthermore, p53 and p16 protein expression was examined by immunohistochemistry. In addition, polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis for detection of mutations in exons 5-8 of the p53 gene was performed in five cases of ETL and three cases of UJ. LOH was found in at least one microsatellite marker at the 9p21 locus in 8 of 22 (36%) ETLs, but not in UJ. Five of nine (56%) tumours composed of large cells showed LOH at 9p21, as opposed to two of eight (25%) tumours with small- or medium-sized cell morphology. The region spanning the p14/p15/p16 gene locus was most frequently affected (five cases); LOH at these markers coincided with loss of p16 protein expression in all of these cases. p53 overexpression was demonstrated in all ETLs examined and in four of seven cases of UJ. However, no alterations of the p53 gene were detected by LOH or PCR-SSCP analysis. The results of this study show that LOH at chromosome 9p21 is frequent in ETL, especially in tumours with large cell morphology; this finding suggests that gene loss at this locus may play a role in the development of ETL.     

Genetic alterations of the tumour suppressor gene regions 3p, 11p, 13q, 17p, and 17q in human breast carcinomas.

Fifty-nine primary breast carcinomas and 11 metastases were examined to identify genetic alterations in the tumour suppressor gene regions 3p, 11p, 13q, 17p, and 17q. Loss of heterozygosity (LOH) was frequently observed on chromosome arms 17p (p144D6 lost in 75%, pYNZ22.1 in 55%, and TP53 in 48% of the primary tumours), 13q (RBI lost in 40% of the primary tumours), and 17q (pRMU3 lost in 35%, pTHH59 in 29%, and NM23HI in 26% of the primary tumours). Loss of all the markers except p144D6 was observed even more frequently in the metastases. Pairwise comparisons for concordance of allele losses on 17p indicated that there might be two genes on 17p implicated in breast cancer development; the TP53 gene and a gene located close to the p144D6 and pYNZ22.1 markers. LOH of the RBI gene was associated with LOH of pYNZ22.1 and p144D6, but not with LOH of TP53. LOH of RBI and TP53 was associated with occurrence of ductal carcinomas, RBI and p144D6 losses with tumour size, and p144D6 losses with positive node status as well. LOH of TP53 and the three 17q markers NM23HI, pTHH59, and pRMU3 was most frequently observed in tumours from postmenopausal women. p144D6 losses occurred most frequently in progesterone receptor-negative tumours, whereas pTHH59 losses occurred most frequently in oestrogen receptor-negative tumours. LOH of the investigated loci was not associated with ERBB2 protooncogene amplification, with positive family history of breast cancer, or with survival.     

Allelic loss on chromosomes 3p, 5q and 17p in renal cell carcinomas

Lossof-heterozygosity (LOH) has been studied on 3p (von Hippel-Lindau gene locus), 5q and 17p (p53 gene locus) by a polymerase chain reaction (PCR)-based strategy in 42 sporadic renal cell carcinomas (RCC). LOH at seven micro-satellite loci on 5q was Investigated because a tumor sup presser gene on 5q involved In the development and/or progression of RCC has not yet been identified. LOH was found In seven (17%) RCC at single or multiple locl on 5q, 38% (11/29 Informative cases) on 3p, and 6% (2/35 Informative cases) on 17p. Replication error (RER) was present in 10% (4/42) RCC at single or multiple loci. The minimum region of deletion on 5q to account for LOH was mapped to 5q31.1 (interferon regulatory factor-1; IRF-1 locus), where LOH was detected In 23% (6/26 Informative cases). LOH on 3p and 5q occurred In both stage 2 and more advanced (stage 3 and 4) tumors at similar incidences (41 and 33% on 3p; and 24 and 22% on 5q, respectively), suggesting that LOH on these chromosomes Is an early genetic event. All RCC exhibiting LOH on 3p or 5q (IRF-1 locus) were the clear cell or the mixed clear and granular cell types. These findings suggest that LOH on 3p and 5q plays an important role in the genesis of clear cell RCC. In addition, only one tumor exhibited LOH on both 3p and 5q, which suggests that LOH occurs not sequentially but independently.     

Deletions of 9p21 and TP53 in bladder cancer.

The objective of this study was to characterize the alterations of 9p21 and TP53 in Korean transitional bladder cancer and to assess the relationship between the histopathologic parameter and the alteration of these genes. Allele loss in 29 surgically resected transitional cell carcinoma was examined by using the multiplex PCR with 7 and 1 microsatellite markers for 9p21 and TP53, respectively. Twenty-one (72%) demonstrated allele loss at 9p21 and/or TP53. Deletion at the 9p21 region was detected in 17(61%) of 28 informative cases at one or more loci, and LOH at TP53 was found in 12(55%) of 22 informative cases. Of 7 microsatellite markers for 9p21, allele loss occurred the most frequently at locus D9S162(69%) and D9S104(69%). Additionally, hemizygous deletion was slightly more common than homozygous deletion. Deletion at 9p21 and TP53 was not related with increased grade. These results suggest that the alteration of 9p21 may be an early event in the development of Korean bladder cancer, while p53 gene may be involved in early event of some bladder cancers as well as in their late events.     

Distinct chromosomal deleted regions defining different subsets of head and neck tumors.

The aim of this work is detecting the loss of heterozygosity (LOH) and its relationship with the development and progression of head and neck cancer. Matched normal and tumor DNA from 81 patients with head and neck cancer were examined for LOH using six microsatellite repeat markers mapped to chromosomal regions 3p13, 6q13, 9p21, 11p15, 17p13.1, and 17q22. LOH frequency at a locus ranged from 21% to 55%. The highest frequencies were at 3p (41%), 9p (48%), and 17p (54%). Thirty-two of 81 tumor samples showed allelic loss at more than one region. Significant associations were found between LOH at 3p and 9p (P = 0.001), 9p and 11p (P = 0.03), and 9p and 17p (P = 0.007). LOH at 11p was frequent in tumors from the oral cavity (5/17), oropharynx (2/7), and hypopharynx (5/10), but absent in tumors from the larynx (0/11) (P = 0.02), and LOH at 17q was observed in tumors from oral cavity (10/30) and hypopharynx (3/9), but not in tumors from the oropharynx (0/10) or larynx (0/13) (P = 0.003). In addition to that, the occurrence of allelic losses at 9p and 17p strongly correlates to tobacco smoking (P = 0.03 and P = 0.006, respectively) and alcohol intake (P = 0.01 and P = 0.005, respectively). These results suggest that tumors from different sites have different LOH patterns and corroborate with epidemiological data implicating tobacco and alcohol in the etiology of head and neck tumors.     

Genetic Changes in Chromosomes 1p and 17p in Thyroid Cancer Progression

Little is known about the genetic alterations that occur during the progression of thyroid neoplasms. To understand better the biology of thyroid tumors, we investigated several genetic loci in benign and malignant thyroid neoplasms. Forty-one thyroid tumors (6 adenomas, 16 papillary, 14 follicular, and 5 anaplastic carcinomas) were studied. Normal and tumor cells were microdissected from paraffin-embedded tissues. DNA was used for polymerase chain reaction-based loss of heterozygosity (LOH) analysis with the following markers: D1S243 (1p35–36), D1S165 (1p36) and D1S162 (1p32), TP53 (17p13), and INT-2 (11q13). Immunohistochemistry for Ki-67 was performed. The Ki-67 labeling index (LI) was the percentage of positive tumor cells. LOH at 1p was seen in 2 of 5 (40%) informative cases of anaplastic carcinoma (2 of 2 at D1S162 and 1 of 2 at D1S165) and in 2 of 11 (18%) informative cases of follicular carcinoma (2 of 7 at D1S243, 2 of 7 at D1S165, and 1 of 6 at D1S162). One anaplastic (20%) and two follicular carcinomas (14%) had LOH in at least two of the 1p loci analyzed. None of the adenomas and papillary carcinomas had LOH at these loci. LOH at 17p and 11q13 were infrequent. Ki-67 LI was 1.4, 7, 16, and 65% in adenomas, papillary, follicular, and anaplastic carcinomas, respectively. Allelic loss at 1p may occur in aggressive types of thyroid carcinoma and may be a marker of poor prognosis. LOH at 1p may represent a late genetic event in thyroid carcinogenesis. LOH at 17p and 11q13 (MEN gene locus) is uncommon in thyroid neoplasms.     

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

Loss of heterozygosity (LOH) affecting loci at 11 p 13 and 11 p 15 occurs in childhood and adult carcinomas, including non-small cell lund cancer (NSCLC). In NSCLC, the highest reported frequency of LOH was 72% at the 11 p 13 catalase (CAT) locus. As this locus is centromeric to the Wilms' tumour (WTI) locus, possible involvement of WTI in the pathogenesis of NSCLC was considered. We thus examined 101 cases of NSCLC for LOH at the WTI and five other polymorphic loci along 11 p. At 11 p 13, the frequencies of LOH were 20% (9/46) at the FSHB locus, 9% (5/53) at the WTI locus, and 15% (6/41) at the CAT locus. The shortest region of overlap (SRO) at 11p13 was mapped centromeric to, but excluding, the WTI locus. Only adenocarcinomas showed LOH in this region. At 11 p 15, LOH affected 23% (18/77) of informative cases, with the highest frequency of 36% at the insulin (INS) locus. The SRO at 11 p15 was mapped telomeric to the RRMI locus. A third region, at 11 p13–15 between WTI and RRMI, 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. Genes Chromosom Cancer 10:183–189 (1994). © 1994 Wiley-Liss, Inc.     

Preferentially deleted chromosome region 9p21 in large hepatocellular carcinomas

The role of somatic deletions in chromosome 9 and chromosome 22 loci in hepatocellular carcinomas (HCC) was studied. Twenty-one paired HCC and adjacent tumor-free liver tissue samples were examined for loss of heterozygosity at six chromosome 9 and ten chromosome 22 loci. Among informative cases, the highest LOH rates were observed at 9p21 (40% or 4/10 at IFNA) and 9q23 (23% or 3/13 at D9S318). Our observed LOH rate at 9p21 was significantly higher than the background level previously reported for the same tumor type. Clinical data indicate that chromosome 9p21 deletions occurred preferentially in larger tumors (>5 cm diameter). However, a sequence analysis of the MTS1 gene coding region in cases of 9p21 LOH did not reveal any change, suggesting another tumor suppressor gene as the LOH target.     

Loss of heterozygosity is detected at chromosomes 1p35-36 (NB), 3p25 (VHL), 16p13 (TSC2/PKD1), and 17p13 (TP53) in microdissected apocrine carcinomas of the breast.

INTRODUCTION: Apocrine carcinomas of the breast are an unusual special category of predominantly AR+, ER-, and PR- breast cancer, characterized by cells with abundant, eosinophilic cytoplasm and nuclei with often prominent nucleoli. To further investigate these lesions, loss of heterozygosity (LOH) was evaluated at multiple chromosomal loci, including loci frequently mutated in breast cancer. MATERIALS AND METHODS: Twenty-five intraductal apocrine carcinomas, 11 invasive apocrine carcinomas, and six apocrine hyperplasias were retrieved from the files of the Armed Forces Institute of Pathology (Washington, DC) and Fairfax Hospital (Fairfax, VA). Cells from lesional as well as normal tissues were microdissected. LOH was performed at a number of chromosomal loci, including loci commonly altered in breast cancer: 1p35-36 (NB), 3p25.5 (VHL), 8p12 (D8S136), 9p21 (p16), 11p13 (D11S904), 11q13 (INT-2 and PYGM), 16p13.3 (TSC2/PKD1 gene region), 17p13 (TP53), 17q13 (NM23), and 22q12 (D22S683). RESULTS: Among informative in situ and invasive apocrine carcinomas, LOH was present in 33% of 15 cases for 17p13 (TP53), as well as 36% of 14 cases for 3p25 (VHL), 30% of 10 cases for 1p35-36 (NB), and 27% of 11 cases for 16p13.3 (TSC2/PKD1). A higher frequency of LOH was noted among invasive apocrine carcinomas (30 to 50%) compared with in situ apocrine carcinomas (23 to 33%) at these loci. LOH was present simultaneously for TP53 and either VHL or NB in five cases. Infrequent (< or =12%) or absent LOH was detected at the remaining loci, including several loci commonly mutated in breast cancer (i.e., INT2, PYGM, and NM23). LOH was not detected in any of the six apocrine hyperplasias. CONCLUSION: An intermediate frequency of allelic loss was detected at multiple tumor suppressor gene loci, including 17p13 (TP53), as well as 1p35-336 (NB), 3p25 (VHL), and 16p13 (PKD1/ TSC2), in apocrine carcinomas of the breast, with a higher overall frequency of LOH noted among invasive tumors compared with in situ tumors. Aside from LOH at p53, LOH was infrequent or absent at several other loci commonly mutated in breast cancer. This preliminary molecular evidence supports immunohistochemical data that apocrine carcinomas of the breast may possess unique mechanisms of carcinogenesis, compared with ordinary ductal carcinomas. However, further study is needed to support this assertion and to determine if the LOH detected is truly etiologic or if it is the result of genetic progression.     

Study of allelic losses on 3p, 6q, and 17p in human urothelial cancer.

Forty-eight transitional cell carcinomas of the bladder and three transitional cell carcinomas of the renal pelvis were examined for loss of heterozygosity (LOH) on chromosomes 3p, 6q, and 17p. The most frequent allelic loss was seen on 17p (18/36, 50%) followed by 6q (6/22, 27%), and 3p (5/22, 23%). In cases with LOH at more than one locus, the same DNA sample often varied in degree of signal reduction for missing alleles. This observation indicates that LOH studies can serve to detect intratumor heterogeneity. No correlation was found between allelic losses at these chromosome arms and tumor grade and stage. Allelic losses on 6q were associated with tumors having a solid growth pattern; in this kind of tumors, allelic losses on 3p were associated with invasion.     

Clinicopathological significance of loss of heterozygosity in intestinal- and solid-type gastric carcinomas: a comprehensive study using the crypt isolation technique.

The clinicopathological significance of loss of heterozygosity (LOH) in gastric carcinoma remains poorly understood. We and other researchers have previously demonstrated that LOH is fairly common in intestinal- and solid-type gastric carcinomas, but rare in diffuse-type tumors. In this study, we investigated the relationship between clinicopathological variables and LOH status in intestinal- and solid-type gastric carcinomas. The crypt isolation technique was utilized to analyze LOH at 1p36, 3p14, 4p15, 5q21-22, 8p11-12, 9p21, 13q22, 17p13.1 18q21 and 22q13.31 in 113 intestinal- and solid-type gastric carcinomas using a polymerase chain reaction assay. Immunostaining with D2-40 and Elastica van Gieson staining were used to detect lymphatic invasion and vessel invasion, respectively. High LOH rates (49-71%) were observed in all chromosomal regions tested. 1p36 loss was significantly associated with advanced tumors and lymph node metastasis. 8p11-12 loss was significantly associated with lymph node metastasis, lymphatic invasion, and vessel invasion. 17p13.1 (TP53) loss was significantly associated with vessel invasion. 22q13.31 loss was significantly associated with advanced tumors, lymph node metastasis, lymphatic invasion, vessel invasion and late TNM stage. No significant associations were observed between LOH at other chromosomal regions and aggressive behaviors. In addition, significantly higher LOH rates at 1p36, 9p21, 18q21 and 22q13.31 were observed in cardiac tumors compared with noncardiac tumors. These results suggest that in intestinal- and solid-type gastric carcinomas, LOH on 3p14, 4p15, 5q21-22, 9p21, 13q22 and 18q21 is associated with carcinogenesis, while LOH on 1p36, 8p11-12, 17p31.1 and 22q13.31 is associated with tumor progression.     

Accumulation of genetic alterations during esophageal carcinogenesis

Using polymerase chain reaction amplification of microsatelliteregions in DNA from 11 epithelial dysplasias of the esophagusand 21 early squamous cell carcinomas, we were able to detectfrequent loss of heterozygosity (LOH) on chromosomes 3p21.3and 9q31 even in low-grade dysplasias. In contrast, we observedfrequent LOHs on chromosomes 9p22 and 17p13 (TP53 locus) onlyin high-grade dysplasias and carcinomas, but not in any low-gradedysplasias. Analysis of LOH at the same four chromosomal regionsIn DNA of five additional minimal carcinomas and accompanyingdysplastic lesions revealed loss of alleles at the loci on 3p21.3and 9q31 throughout various degrees of dysplasia and carcinoma;again, LOHs on 9q22 and 17p13 occurred only in high-grade dysplasiaand carcinoma in situ. Our results indicated that Inactivationof putative tumor suppressor genes on 3p21.3 and 9q31 may beearly genetic events during esophageal carcinogenesis, and thatadditional genetic alterations on 9p22 and 17p13 probably playroles in progression.     

LOH at the APC/MCC gene (5Q21) is frequent in early stages of non-small cell lung cancer.

Lung cancer is the leading cause of death in both women and men in the United States and many European countries. Molecular cytogenetic and LOH analyses of non-small cell lung cancer have shown somatic genetic alterations in a variety of chromosomes, such as 1p, 3p, 5q, 8p, 9p, 11p, 11q and 17p. Allelic deletions of the known tumor suppressor gene APC at 5q21 are frequently observed in advanced stages of lung cancer and have been correlated with poor prognosis in previous reports. We investigated 33 cases of NSCL for LOH at 5q21: 22 squamous cell and 11 adenocarcinomas. Normal and tumor cells were microdissected from paraffin embedded tissues and PCR amplification was performed utilising the specific markers D5S299 and D5S346 at 5q21 and PYGM at 11q13, respectively. Clinicopathological data, survival and recurrence rates were obtained in all cases. We detected LOH at 5q21 in 4/9 (44%) informative adenocarcinomas and in 13/16 (81%) informative SCC. LOH was frequent in early stages (12/15 stage I cases) and did not correlate with recurrence or poor survival. Our results show that LOH at 5q21 is more frequent in squamous cell carcinomas than in adenocarcinomas, is frequent in early stages of the disease, and does not have prognostic significance.     

Chromosome 8p alterations in sporadic and BRCA2 999del5 linked breast cancer

Chromosomal losses involving the short arm of chromosome 8 are frequent in a variety of tumour types, including breast cancer, suggesting the presence of one or more tumour suppressor genes in this region. In this study, we have used 11 microsatellite markers to analyse loss of heterozygosity (LOH) at chromosome 8p in 151 sporadic breast tumours and 50 tumours from subjects carrying the BRCA2 999del5 mutation. Fifty percent of sporadic tumours compared to 78% of BRCA2 linked tumours exhibit LOH at one or more markers at 8p showing that chromosome 8p alterations in breast tumours from BRCA2 999del5 carriers are more pronounced than in sporadic breast tumours. The pattern of LOH is different in the two groups and a higher proportion of BRCA2 tumours have LOH in a large region of chromosome 8p. In the total patient material, LOH of 8p is associated with LOH at other chromosome regions, for example, 1p, 3p, 6q, 7q, 9p, 11p, 13q, 17p, and 20q, but no association is found between LOH at 8p and chromosome regions 11q, 16q, 17q, and 18q. Furthermore, an association is detected between LOH at 8p and positive node status, large tumour size, aneuploidy, and high S phase fraction. Breast cancer patients with LOH at chromosome 8p have a worse prognosis than patients without this defect. Multivariate analysis suggests that LOH at 8p is an independent prognostic factor. We conclude that chromosome 8p carries a tumour suppressor gene or genes, the loss of which results in growth advantage of breast tumour cells, especially in carriers of the BRCA2 999del5 mutation.


Keywords: chromosome 8; BRCA2; LOH; breast cancer     

No evidence of microsatellite instability but frequent loss of heterozygosity in primary resected lung cancer

We examined microsatellite instability and loss of heterozygosity (LOH) in primary lung tumors from 93 cancer patients, using 16 microsatellite markers. The cases studied included 87 non-small-cell lung cancers (NSCLC) and six small-cell lung cancers (SCLC). All the patients except two were current or former smokers. The microsatellite markers were all dinucleotide repeat sequences from chromosomal locations 1p, 3p, 5q, 8p, 9p, 10p, 11p, 13q, and 17q. None of the tumors showed microsatellite instability (0/93). In NSCLC, 28% (24/87) of the cases showed LOH in at least one locus, whereas, in SCLC, 67% (4/6) had allelic losses. The frequency of LOH differed between the various cell types of NSCLC. The highest frequency was seen in large cell carcinoma (3/6, 50%) followed by squamous cell carcinoma (16/43, 37%) and adenocarcinoma (5/35, 14%). The most common site of LOH was 3p, where markers D3S1284, D3S659, D3S1289, D3S966, D3S647, and D3S1038 were studied. LOH, studied with 9p markers (D9S126, D9S171, D9S162), was less common. The present results, together with earlier reports, suggest that smoking-related primary lung cancers seldom show microsatellite instability but are characterized by frequent LOH. Environ. Mol. Mutagen. 30:217–223, 1997. © 1997 Wiley-Liss, Inc.     

Loss of heterozygosity in adenomyosis on hMSH2, hMLH1, p16Ink4 and GALT loci

Adenomyosis is a gynecological condition in which tissue histologically similar to that in endometrium is found within the myometrium in the uterus. Although, lesions of both adenomyosis and endometriosis are identical to their sources with respect to structure and function, they are generally regarded as separate and distinct nosologic processes. In this study, we used 17 microsatellite markers, in four tetraplex and one single PCR assay, to determine the incidence of loss of heterozygosity (LOH) in 31 cases of adenomyosis. The markers used are located close to tumor suppressor genes, DNA repair genes, and genes which are thought to be involved in endometriosis. Moreover, the markers were involved in regions frequently lost in ovarian cancer, on chromosomal arms 1p, 1q, 2p, 2q, 3p, 9p, 9q, 17p and 17q. Nine samples (29.0%) showed LOH in at least one locus. Loci 2p22.3-p16.1, 3p24.2-p22 and 9p21 exhibited imbalance (19.4%, 9.7% and 6.5% respectively). This is the first report, that LOH occurs in adenomyosis. The regional chromosomal losses were detectable early during the development of this condition. In addition, hMSH2, hMLH1, p16Ink4 and GALT genes were associated for the first time with adenomyosis and its pathogenesis.     

Multitarget FISH and LOH analyses at chromosome 3p in non-small cell lung cancer and adjacent bronchial epithelium

Multitarget fluorescence in situ hybridization (FISH; LAVysion, Vysis, Downers Grove, IL) targeting chromosomes 6p11-q11, 7p12, 8q24, and 5p15.2 was compared with results of microsatellite studies at chromosome 3p to identify molecular changes associated with tobacco use and tumor development in non-small cell lung cancer (NSCLC). Analyses were performed on 26 NSCLCs and matched benign bronchial epithelium; samples from 10 patients without NSCLC served as control samples. Significant molecular differences between tumor tissue and corresponding benign bronchi were found using FISH (P = .001) and loss of heterozygosity (LOH) analysis (P = .031). Bronchial epithelium from patients with NSCLC was genetically different from epithelium from patients without NSCLC in FISH analysis (P = .025). Receiver operating characteristic curve analysis revealed an optimal cutoff value of 5% atypical cells for bronchial epithelium. There was no statistical correlation with the patient's smoking history, and LOH analysis of bronchi did not differentiate between patients with and without NSCLC. Multicolor FISH analysis is able to detect a tumor-associated molecular field effect in bronchi adjacent to NSCLC.     

肠隐窝异常病灶2,3,5,11,17和18号染色体部分位点的杂合子丢失

目的;探讨肠隐窝异常病灶（ACF）作为结直肠癌最早期癌前形态变化的分子基础。方法：微解剖分离提取34例ACF和35例癌组织的基因组DNA,全自动DNA测序仪毛细管凝胶电泳检测ACF和癌组织在2,3,5,11,17和18号染色体上9个微卫星位点的杂合子丢失（LOH）。结果：ACF LOH的发生频率（41．18％）低于癌组织（68．57％）（P＜0．05）,且两者的LOH发生频率在18q12、5q12、3p21、17q21、17q11、11p13和2p16位点LOH有相似的谱形。在18q12、5q12、3p21、17q21和17q11位点发生频率较高,在11p13和2p16位点较低。ACF在18q21和5q21位点LOH明显低于癌组织（P＜0．05）。癌组织LOH与肿瘤的部位、大体类型、组织学类型和Dukes分期均无关。LOH呈阳性的ACF,其同来源的癌组织多见于左半结肠,大体以隆起型为主。结论：（1）ACF作为结直肠癌黏膜癌前早期的形态改变有其分子遗传学证据;（2）进一步证实结直肠癌的发生发展是多基因受累、多步骤的复杂过程。     

Analysis of chromosome 17p13 (p53 locus) alterations in gastric carcinoma cells by dual-color fluorescence in situ hybridization.

Chromosome 17 and p53 gene locus alterations were determined on 67 gastric carcinomas by dual-color fluorescence in situ hybridization, using probes for centromere 17 and the 17p13.1 (p53 locus). The results were compared with loss of heterozygosity (LOH) at 17p13.3, direct sequencing of exons 5 to 9 of p53, and nuclear overexpression of p53 protein. Deletion of p53 was found in 26 of 67 tumors (39%). All 26 also showed LOH at 17p13.3, frequently overexpressed p53 protein, and had polysomy 17. The functional loss of p53 gene in these tumors, 85% of which were of intestinal type, appears to be caused by both deletion of 17p13.1 and missense mutation of the remaining allele. There were 9 tumors that had neither deletion nor LOH but had a large proportion of cancer cells that overexpressed p53 election. Despite evidence of LOH, there was no p53 deletion in 11 tumors. Finally, 21 tumors, mostly of diffuse type, showed neither deletions, LOH, nor p53 overexpression. Our data suggest that in gastric cancer, deletion of 17p is principally responsible for the allelic loss at the p53 gene and that analysis of deletions by the dual-color fluorescence in situ hybridization is a sensitive and useful approach to clarify chromosomal aberrations.     

Loss of heterozygosity at 9q32-33 (DBC1 locus) in primary non-invasive papillary urothelial neoplasm of low malignant potential and low-grade urothelial carcinoma of the bladder and their associated normal urothelium

Tumour recurrence has a major impact on patients with non-invasive papillary urothelial tumours of the bladder. To explore the role of DBC1 (deleted in bladder cancer 1 locus), a candidate tumour suppressor gene located at 9q32-33, as prognostic marker we have performed loss of heterozygosity (LOH) testing in 49 patients with primary papillary urothelial tumours and associated normal urothelium. Data from the 38 tumours and 11 specimens of normal urothelium that were informative in the LOH study (D9S195 marker) showed that LOH in urothelium (45.4%) but not in non-invasive tumours (60.5%) was associated with tumour recurrence (p = 0.026) but not to grade or progression. Also, tumours whose normal urothelium had LOH were larger (p = 0.020) and showed cyclin D1 over-expression (p = 0.032). Non-significant increased expression of p53, p21Waf1, apoptotic index and tumour proliferation, and decreased expression of p27Kip1 or cyclin D3 also characterized tumours whose normal urothelium had LOH. The expression of these G1-S modulators, apoptotic index and tumour proliferation was more heterogeneous in papillary urothelial tumours, irrespective of having retained heterozygosity or LOH. Also, Bax expression decreased in papillary urothelial tumours having LOH (p = 0.0473), but Bcl-2 was unrelated to LOH status. In addition, FGFR3 protein expression decreased in LOH tumours (p = 0.036) and in those having LOH in their normal urothelium (p = 0.022). FGFR3 immunohistochemical expression was validated by western blot in selected cases. The survival analysis selected LOH in normal urothelium as a marker of disease-free survival (log-rank 5.32, p = 0.021), progression-free survival (log-rank 3.97, p = 0.046) and overall survival (log-rank 4.26, p = 0.038); LOH in tumours was significant in progression-free survival (log-rank 3.83, p = 0.042). It is concluded that LOH at the DBC1 locus in normal urothelium seems to be relevant in the prognosis of non-invasive papillary tumours of the bladder via selecting cases with increased proliferation, frequent alterations of the G1-S phase modulators, and decreased FGFR3 protein expression.