Allelic loss of chromosome 13q14.3 in human oral cancer: Correlation with lymph node metastasis

To evaluate the role of chromosome 13 deletions in oral squamous cell carcinoma (SCC) progression and to define the precise localization of putative tumor suppressor genes, we studied tumors from 34 unrelated patients with oral SCC by the polymerase chain reaction (PCR)-loss of heterozygosity (LOH) assay, using 18 different polymorphic loci. Chromosome 13q allelic losses (LOH) were observed in 67.6% at 1 or more loci. These results enabled the identification of a putative minimal region of deletion mapped at 13q14.3. The commonly deleted region is located close, but telomeric to the RB1 locus. We also examined the same samples for inactivation of the RB1 gene by immunohistochemical analysis of paraffin-embedded samples, but no significant variation in RB protein expression was detected. In addition, we also performed PCR-single-strand conformational polymorphism (SSCP) analysis to detect any mutation of the RB1 gene using 52 primer pairs, which covers all exons of this gene. We found no mutations of the RB1 gene in our samples. Interestingly, we found significant correlation between LOH of 13q14.3 and lymph node metastasis. Our results indicate that LOH of 13q is a common event in oncogenesis and/or progression of oral SCC, and also suggest the existence of a new suppressor gene near D13S273-D13S176 loci which may play a role in these events. Int. J. Cancer (Pred. Oncol.) 79:312–317, 1998. © 1998 Wiley-Liss, Inc.     

Frequent allelic loss/imbalance on the long arm of chromosome 21 in oral cancer: evidence for three discrete tumor suppressor gene loci.

Frequent allelic imbalances including loss of heterozygosity (LOH) and microsatellite instability (MI) on the long arm of chromosome 21 (21q) have been found in several types of human cancer. This study was designed to identify tumor suppressor locus (or loci) associated with oral squamous cell carcinoma (SCC) on 21q. Among 38 patients with oral SCC tested, 15 (44%) of 34 informative cases showed LOH at one or more loci. Deletion mapping of these 15 tumors revealed three discrete commonly deleted regions on the chromosome arm. A minimal region with frequent LOH was found at the marker D21S236 mapped on 21q11.1. Another region of frequent deletion was identified between markers D21S11 and D21S1436 on 21q21, and a further commonly deleted region was found at D21S1254 on 21q22.1. In addition, we have detected MI on the chromosome arm in our oral SCC samples with significant correlation with tumor stage. Thus, our results strongly suggest that allelic imbalances on 21q may be involved in the development of oral SCC; and that at least three different putative tumor suppressor genes contributing to the pathogenesis of this disease are present on 21q.     

Allelic loss of chromosome 2 in human oral squamous cell carcinoma: correlation with lymph node metastasis

To evaluate the role of chromosome 2 deletions in human oral squamous cell carcinoma (SCC) progression and to define the precise location of putative tumor suppressor genes, we examined 40 primary tumors and seven lymph node metastatic tumors from 40 patients with oral SCC by the polymerase chain reaction (PCR)-loss of heterozygosity (LOH) assay, using 10 different polymorphic loci on the long arm of chromosome 2. LOH was observed in 67.5% of the patients at one or more loci on the chromosome 2q. Two commonly deleted regions with high frequency of LOH, D2S1327 region at 2q32-35 (31.6%) and D2S206 region at 2q36 (36.7%), were identified by the deletion mapping of chromosome 2q, suggesting the presence of putative tumor suppressor genes associated with oral SCC. Examination of seven metastatic tumors also revealed four commonly deleted regions, D2S436, D2S1327, D2S155, and D2S164. Of these four regions D2S1327 region has no significant increase in the frequency of LOH between in primary tumors and in metastatic tumors. However, at other three regions the frequencies were much increased in metastatic tumors, comparing the results in primary tumors. Especially, very high frequencies of LOH in metastatic tumors were detected at two regions on 2q35, 100.0% at D2S155 and 57.1% at D2S164, suggesting the significant relationship between lymph node metastasis and LOH at these two regions. Our results indicate that LOH on chromosome 2q is a common event in oncogenesis and/or progression of oral SCC, and also suggest that the LOH at 2q35 play a significant role in the lymph node metastasis.     

Allelic loss on chromosome 17 in human ovarian cancer

In order to identify a common region of deletion on chromosome 17 potentially containing a tumor-suppressor gene, 27 ovarian carcinomas and 3 ovarian tumors of low malignant potential (LMP) were examined for loss of heterozygosity (LOH) at 6 p arm and 10 q arm loci. Ninety percent of all tumors had deletions at one or more loci. On the p arm, there was a single near-common region of deletion on 17p 13.3 (D/7S30/ pYNZ22.1; 86% LOH), an intervening locus with a low LOH rate, and a more proximal locus on 17p11.2 (D/7S58/pEW301; 82% LOH) with a high LOH rate. In less aggressive tumors, LOH at Df 7S30 was not accompanied by LOH at p53. The q arm had a common region of deletion for high-stage carcinoma at D/7S579 (Mfd 188; 74% LOH) on q21, a locus tightly linked to the familial breast-ovarian-cancer syndrome (BRCAI) locus. D/7S579 was lost in all informative high-stage carcinomas and retained in all low-stage carcinomas and tumors of LMP. There may be at least 2 tumor-suppressor genes, an early-acting gene on the p arm and a gene on the q arm involved in tumor progression and metastasis.     

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.     

Allelic imbalance on the long arm of chromosome 5 in oral squamous cell carcinoma

To obtain a more detailed estimate of chromosome 5 loci involvement in oral squamous cell carcinoma (SCC), thirty-two oral SCCs were examined for loss of heterozygosity (LOH) on the long arm of chromosome 5 (5q) by PCR-LOH assay using thirteen microsatellite markers. LOH was observed in 16 (51.6%) of 31 informative cases. The incidence or the number of regions showing LOH was significantly higher in moderately and poorly differentiated tumors than in the well differentiated ones. Among the loci tested, D5S178 exhibited LOH in 11 (39.3%) of 28 cases, suggesting this to be the site, at 5q, of a novel candidate tumor suppressor gene. These data indicate that the incidence of LOH at chromosome 5q is high and is associated with oral tumor differentiation.     

Frequent loss of heterozygosity of the long arm of chromosome 7 is closely associated with progression of human gastric carcinomas

Loss of heterozygosity (LOH) on the long arm of chromosome 7 was examined using 5 polymorphic marker probes on 98 gastric carcinomas to elucidate a novel locus for development and progression of the tumors. Twenty-six (32%) of 82 informative cases showed LOH on 7q on at least one locus of 5 loci. Among 5 loci, LOH at D7S95 locus was most frequent, the incidence being 53% in well-differentiated gastric carcinomas and 33% in poorly differentiated and scirrhous gastric carcinomas respectively. At 3 loci, c-met, D7S63 and D7S22, the incidence of LOH was about 30% and 10% in well-differentiated and poorly differentiated gastric carcinoma cases respectively. In contrast, LOH at D7S64 was not detected in any gastric-carcinoma cases. Deletion mapping of 7q revealed that D7S95 locus was the essential region of LOH. Eight (62%) of 13 cases with LOH at D7S95 locus belonged to the most advanced stage grouping. Furthermore, 6 (75%) of 8 cases with abdominal dissemination showed LOH at D7S95. Therefore, cases with LOH at D7S95 showed significantly worse prognosis than the cases without the LOH in the stage-III and stage-IV groups. These findings overall suggest that D7S95 locus on 7q may contain a candidate suppressor gene for the progression of gastric carcinoma.     

Mutational and LOH analyses of the chromosome 4q region in esophageal adenocarcinoma

OBJECTIVE: Mortality due to esophageal adenocarcinoma has risen markedly, but the molecular mechanisms underlying this carcinogenesis are still incompletely understood. Findings from loss of heterozygosity (LOH) studies have suggested that the long arm of chromosome 4 might harbor tumor suppressor genes relevant to esophageal adenocarcinoma. METHODS: We performed LOH analysis of 4q in esophageal adenocarcinomas. Regions of LOH were further evaluated by studying two candidate tumor suppressor genes, hCDC4 and CARF, located within them. RESULTS: 54% of the adenocarcinomas examined showed allelic deletion. LOH was observed in 53, 40, 32, 38, and 27% of tumors at positions D4S1554 (the locus of CARF), D4S1572, D4S1548, D4S2934, and D4S3021, respectively. An area of allelic deletion (spanning 3 million bases) was identified at 4q31.1-3 in 37% of tumors. This region harbors a candidate tumor suppressor gene: hCDC4. However, sequencing of the coding regions of CARF and hCDC4 at 4q35 and 4q31, respectively, did not identify mutations. CONCLUSIONS: Our findings demonstrate frequent LOH in esophageal adenocarcinoma at several loci including a novel area of allelic deletion at 4q31.1-3. The results imply that mutational or other alterations at these loci may be involved in the pathogenesis of esophageal adenocarcinoma. Candidate tumor suppressor genes located within these regions merit further study.     

Comprehensive allelotyping of human intrahepatic cholangiocarcinoma.

We performed a genome-wide scan for loss of heterozygosity (LOH) in 22 intrahepatic cholangiocarcinoma (ICC) cases using 168 polymorphic microsatellite markers throughout all of the human chromosomes and 48 markers of which LOH is reportedly characteristic of hepatocellular carcinoma (HCC). Markers with LOH in more than 30% of informative cases were observed at 21 loci. Among these, eight markers on 6q (three loci), 4q (two loci), 9q, 16q, and 17p shared high frequencies of LOH with HCC in our previous study. As for gross appearance, mass-forming type tumors showed higher frequency of LOH (P < 0.001) compared with other types. Compared by tumor size (< or =5 cm versus >5 cm), number (multiple versus solitary), and the International Union Against Cancer TNM classification (stage IVB versus II-IVA), LOH was observed more frequently in advanced stages (P < 0.01, respectively). However, LOH frequency does not differ regardless of lymph node status (pN0 versus pN1). Frequent LOH on 1p36 including the p73 locus was noted in large tumors without lymph node metastasis. These suggest that ICC shares some common carcinogenic steps with HCC such as LOH of 4q and 6q and that inactivation of tumor suppressor genes on chromosome 1p36 contributes to progression of ICC but not to metastatic traits.     

散发性结直肠癌染色体5p15区杂合性缺失精细定位

目的 研究散发性结直肠癌5号染色体的杂合性缺失,寻找新的结直肠癌抑癌基因.方法 取83例结直肠癌患者的肿瘤和正常组织,先后应用分布于5号染色体上的16对微卫星DNA标记和5p15区D5S416附近的6对微卫星DNA标记进行聚合酶链反应(PCR),PCR产物在自动荧光测序仪进行电泳3h,以GeneScan3.1和Genotyper2.1软件进行基因分型.结果 经5号染色体上的16对微卫星DNA标记的杂合性缺失分析,发现散发性结直肠癌5号染色体上有2个明显的高频杂合性缺失区域,即染色体短臂上的D5S416位点和染色体长臂上的D5S428～D5S410区.进一步对5p15区的精细定位,界定了1个遗传距离为1 cM大小、跨越D5S416位点的杂合性缺失区,该区的位点大致顺序是pter-D5S630-D5S1987-D5S1991-D5S1954-D5S1963-D5S416-D5S2114-D5S486.本组54例有效标本的杂合性缺失率达48.2%.结论 散发性结直肠癌在5号染色体短臂存在1个杂合性缺失区域,即5p15.2-15.3,该区很可能存在1个或多个与结直肠癌相关的新的抑癌基因.     

Frequent Loss of Heterozygosity at the MCC Locus on Chromosome 5q21-22 in Sporadic Colorectal Carcinomas

Recent studies have identified a gene on chromosome 5q, designated MCC (mutated in colorectal cancers), as a candidate for the putative colorectal tumor suppressor gene that is located at 5q21. We examined loss of heterozygosity (LOH) at the MCC locus and its vicinity in sporadic colorectal carcinomas, using 12 RFLP (restriction fragment length polymorphism) markers. One clone, L5.71, had been used to identify the MCC gene; all 12 markers also had tight linkage to the gene responsible for adenomatous polyposis coli. All 40 cases studied were informative with at least one marker, and 22 of them (55%) showed LOH at one or more loci. LOH in the tumors was more frequent in the immediate vicinity of L5.71 than in distant parts of the chromosome, and a common region of deletion was detected between markers L5.62 and 15A6. In one case, alleles were retained at L5.71 and at loci proximal to L5.71, but alleles were lost at loci distal to L5.71. In another case, both alleles were retained at L5.71 but alleles were lost at loci proximal and distal to L5.71. These results support the conclusion that a tumor suppressor gene for colorectal carcinoma is located within or around locus L5.71.     

Loss of heterozygosity at locus F13B on chromosome 1q in human medulloblastoma

Medulloblastoma is a primitive neuroectodermal tumor of the cerebellum with poorly understood pathogenesis. Previous studies have reported loss of heterozygosity (LOH) on chromosome arms 17p, 11p and 9q and cytogenetic abnormalities of chromosome 1 in medulloblastoma. We have used the polymerase chain reaction to amplify 10 microsatellites on the short arm and B microsatellites on the long arm of chromosome 1 to assess allelic loss in 22 medulloblastomas. Loss of heterozygosity (LOH) on chromosome 1 was found in 9 cases. Eight medulloblastomas (36%) showed an interstitial LOH on chromosome 1q. The common region of overlap was mapped between DISI604 and DIS237 and included the locus F13B in the chromosomal region 1q31–q32.1. An additional tumor had LOH in a proximal region of 1p, but did not exhibit LOH on 1q. None of the medulloblastomas exhibited LOH of the telomeric portion of chromosome 1p, which has been associated with several other human malignancies. Our data suggest the presence of a putative tumor suppressor gene located near the locus F13B on chromosome arm 1q that appears to be involved in the pathogenesis of medulloblastoma. © 1996 Wiley-Liss, Inc.     

Frequent loss of heterozygosity at the MCC locus on chromosome 5q21-22 in sporadic colorectal carcinomas.

Recent studies have identified a gene on chromosome 5q, designated MCC (mutated in colorectal cancers), as a candidate for the putative colorectal tumor suppressor gene that is located at 5q21. We examined loss of heterozygosity (LOH) at the MCC locus and its vicinity in sporadic colorectal carcinomas, using 12 RFLP (restriction fragment length polymorphism) markers. One clone, L5.71, had been used to identify the MCC gene; all 12 markers also had tight linkage to the gene responsible for adenomatous polyposis coli. All 40 cases studied were informative with at least one marker, and 22 of them (55%) showed LOH at one or more loci. LOH in the tumors was more frequent in the immediate vicinity of L5.71 than in distant parts of the chromosome, and a common region of deletion was detected between markers L5.62 and 15A6. In one case, alleles were retained at L5.71 and at loci proximal to L5.71, but alleles were lost at loci distal to L5.71. In another case, both alleles were retained at L5.71 but alleles were lost at loci proximal and distal to L5.71. These results support the conclusion that a tumor suppressor gene for colorectal carcinoma is located within or around locus L5.71.     

Frequent loss of heterozygosity on chromosome 10p14-p15 in esophageal dysplasia and squamous cell carcinoma

High frequencies of loss of heterozygosity (LOH) on chromosome 10p14-p15 have been reported in various tumors, including glioma, pulmonary carcinoid and cervical, hepatic and prostatic carcinomas. These findings suggest the presence of a tumor suppressor gene at the loci. However, analysis of LOH on chromosome 10p14-p15 in esophageal tumors has not been reported. Therefore, we examined LOH on chromosome 10p14-p15 in 88 esophageal squamous cell carcinomas (SCC) (35 superficial- and 53 advanced-types) and 44 dysplasias by microsatellite assay. Five oligonucleotide primer sets for microsatellite loci D10S191, D10S501, D10S559, D10S558 and D10S249 were used. In dysplasias, frequent LOH was detected with markers D10S191 (26%) and D10S249 (33%). In superficial esophageal SCCs, frequent LOH was detected with markers D10S191 (26%), D10S559 (50%), D10S558 (29%) and D10S249 (33%). In advanced esophageal SCCs, we found frequent LOH was detected with markers D10S191 (38%), D10S501 (25%) and D10S559 (30%). There were no significant correlations between LOH on chromosome 10p14-p15 and clinicopathologic features, including patient age, sex, tumor location, depth of invasion and lymph node metastasis. These data suggest that a putative tumor suppressor gene for esophageal carcinogenesis may be located on chromosome 10p14-p15 and that malfunction of this gene may be involved in the development but not progression of esophageal tumors.     

Microsatellite analysis reveals deletion of a large region at chromosome 8p in conventional renal cell carcinoma

Loss of heterozygosity (LOH) at chromosome 8p is associated with the progression of conventional (non‐papillary) renal cell carcinomas (RCC). To determine the tumor suppressor gene locus, we carried out a deletion mapping of chromosome 8p at 10 microsatellite loci in 96 RCCs. LOH occurred in 32% of the tumors. The smallest overlapping region of deletion at chromosome 8p11.2–p23.1 corresponds to approximately 34‐cM genetic distance. No small interstitial deletion was seen. Int. J. Cancer 80:22–24, 1999. © 1999 Wiley‐Liss, Inc.     

Deletion mapping on the short arm of chromosome 1 in Merkel cell carcinoma

Twenty-two Merkel cell carcinoma (MCC) biopsies and six cell lines from 24 patients were examined for loss of heterozygosity (LOH) at 11 loci on 1p and one on 1q, to determine LOH regions on chromosome 1p. Sixteen (73%) tumors had LOH for at least one locus; 14 demonstrated LOH at more than one locus, and 7 (29%) samples had more than one region of loss, with 4 of these having loss at all informative loci on 1p. Three common regions of loss (SRO) were defined by LOH in multiple tumors. Eight samples demonstrated LOH between D1S214 and D1S160 (1p36), seven between D1S234 and D1S186 (1p35), and 11 for the region centromeric of D1S211 and D1S220 (1p32-1p33). Seven samples (29%) demonstrated more than one region of loss. LOH on 1p occurs frequently in MCC and more than one tumor suppressor gene on 1p is likely to play a role in the development of this tumor type.     

Loss of heterozygosity in the tuberous sclerosis gene associated regions in adenocarcinoma of the lung accompanied by multiple atypical adenomatous hyperplasia

To investigate the potential allelic loss of tumor suppressor gene loci in the tuberous sclerosis complex (TSC)-associated regions located on the long arm of chromosome 9 (9q) and on the short arm of chromosome 16 (16p) in human lung carcinoma, we analyzed 21 paired normal and tumor DNAs with 11 polymorphic markers on the chromosomes. All tumors were adenocarcinoma of the lung, which included 9 adenocarcinomas with associated multiple atypical adenomatous hyperplasia (AAH). A precise microdissection technique followed by polymerase chain reaction (PCR) amplification to prevent under-evaluation of loss of heterozygosity (LOH) was used. Twelve of the 21 (57%) adenocarcinomas displayed LOH on 9q. Five of the 21 adenocarcinomas (24%) showed LOH at all informative loci on 9q, whereas 7 (33%) demonstrated partial LOH on 9q34. Among these 21, 5 (24%) showed partial LOH between D9S149 and D9S150, where TSC1 is located. The incidence of associated AAH was significantly higher in adenocarcinoma harboring a partial LOH in the TSC1-associated region (p = 0.0048). Twelve of the 21 (57%) adenocarcinomas displayed LOH on 16p. No significant differences in the clinico-pathological characteristics could be discerned between adenocarcinomas with and without LOH on 16p. When combining these data, a partial LOH at TSC1- and/or TSC2-associated loci was observed more frequently in cases with well-differentiated adenocarcinoma (p = 0.086) and associated AAH (p = 0.081). In conclusion, our results suggest that the TSC-associated regions are new candidate loci for tumor suppressor genes in lung adenocarcinoma, especially when it is accompanied by multiple AAH. Int. J. Cancer (Pred. Oncol.) 79:384–389, 1998. © 1998 Wiley-Liss, Inc.     

Allelic loss on the short arm of chromosome 8 in oral squamous cell carcinoma.

Allelic deletions on the short arm of chromosome 8 (8p) are frequent events in many different types of malignant tumors, including head and neck tumors and oropharyngeal cancers. These regions are thought to harbor tumor suppressor genes. However, there has been no detailed analysis of loss of heterozygosity (LOH) on the chromosome arm 8p in oral squamous cell carcinoma (SCC). In order to estimate details of 8p loci involved in oral SCC, 32 patients with oral SCCs were examined for the LOH state 8p by PCR-LOH assay using 14 microsatellite markers. Based on our results a detailed deletion map of 8p showed LOH in at least one of the loci tested in 62.5% (20 of 32) of patients; and microsatellite instability (MI) was observed in 50% (16 of 32). The frequent LOH on this chromosome arm was identified at D8S87 and D8S258, mapped on 8p12 and 8p22, respectively. Fisher's exact test revealed no significant statistical correlation between the incidence of LOH or MI and clinicopathological features. Our observations indicate that the short arm of chromosome 8 may play a role in the pathogenesis of oral SCC; and that the two loci identified in this study may be tumor suppressor gene loci on 8p.     

Identification of a minimal deletion region on chromosome 5q in Chinese esophageal squamous cell carcinomas

The existence of unknown tumor suppressor gene(s) other than the APC gene has been hinted on 5q for esophageal squamous cell carcinoma (ESCC). In order to define minimal deletion intervals on 5q in ESCC and investigate the potential tumor suppressor gene(s), 9 microsatellite markers scattering the region from 5q22 to 5q35 were chosen for loss of heterozygosity (LOH) analysis in 50 primary ESCC from northern China. The results showed that six cases presented coexistence of LOH for three consecutive adjacent chosen markers, suggesting a minimal deletion region covering approximately 272 kb located on 5q23 from D5S1384 to D5S1505. It was a novel deletion region that was so far never reported in ESCC. Significant higher frequencies of LOH were observed in tumors with lower pathological grade at the locus D5S820 and with lymph node metastasis at the locus D5S408. The data suggested the possibility that one or more putative candidate tumor suppressor gene(s) on 5q23 might play an important role in the development and/or progression of ESCC.     

LOSS OF HETEROZYGOSITY ON CHROMOSOME 13 IN SQUAMOUS CELL CARCINOMAS OF THE LARYNX

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