Allelic loss in ovarian cancer

Loss of heterozygosity (LOH) was examined at 86 loci distributed on every chromosomal arm in 50 human ovarian tumors. Frequent allele losses were observed on chromosomes 13q (42%), 17p (42%), 17q (45%), and Xp (41%). Deletion mapping on chromosome 17 revealed a candidate gene on the long arm distal to D17S41/S74 for ovarian cancer which is distant from the locus for early onset breast cancer. LOH on chromosome 17q was found to be concordant with LOH on chromosomes 3p, 13q, 17p and Xp suggesting that it may be an early event in neoplastic development. These findings indicate that multiple tumor-suppressor genes for ovarian cancer possibly exist on chromosomes 13q, 17, and/or Xp and provide the basis for the identification of candidate gene(s) associated with ovarian cancer. The chromosomal mechanisms resulting in allele losses in ovarian cancer include deletion, deletion/duplication, mitotic recombination and monosomy, in concordance with the developed genetic model.     

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.     

Allelic loss at chromosome 8p in human breast-cancer

Loss of heterozygosity (LOH) at loci from the short arm of chromosome 8 has been shown to occur in several types of carcinomas. The consensus deletion region has been recently mapped at 8p21-p22, distal to D8S283 and NEFL loci, and proximal to LPL and D8S265 loci. We report LOH at D8S133, a marker located in this consensus region, in a panel of breast tumor samples. LOH at this locus was observed in about 20% of the tumors.     

Comparative analysis of loss of heterozygosity of specific chromosome 3, 13, 17, and X loci and TP53 mutations in human epithelial ovarian cancer

We previously reported the identification of three minimal regions of deletion on the short arm of chromosome 3 (3p) in epithelial ovarian tumor specimens, suggesting that the inactivation of tumor-suppressor genes in these regions may be important in terms of ovarian tumorigenesis. Another previous study of ovarian cancer observed that allele loss of chromosome 179 was frequently found in ovarian tumors that also showed loss of heterozygosity (LOH) of chromosomes 3p, 13q, 17p, and Xp. In an independent study, we also reported a high frequency of LOH for selected chromosome 17 loci in high-grade and late-stage ovarian tumors. We have extended our LOH analysis of chromosome 3p to include 102 ovarian tumor specimens (29 and 73 samples were previously examined for LOH of chromosome 3p and 17 markers, respectively), using additional polymorphic markers, to assess the coordinate LOH of loci representing the three chromosome 3p minimal regions of deletions [von Hippel-Lindau syndrome (VHL), thyroid hormone receptor beta, and fragile histidine triad (FHIT)] and LOH of other important loci [tumor protein 53 (TP53), breast cancer 1 early onset (BRCA1), breast cancer 2 early onset, retinoblastoma 1, ornithine carbamoyltransferase, and androgen receptor] or somatic mutations in TP53. There was a significant association between LOH of any chromosome 3p marker and LOH of any chromosome 17 marker (P = 0.026). The frequency of LOH at the TP53 locus was higher in the group of samples that displayed LOH of a 3p marker (P = 0.019), as was the frequency of LOH at the BRCA1 locus (P = 0.014). LOH of chromosome 3p was noted in four specimens that did not display LOH of either the BRCA1 or the TP53 locus, indicating that LOH of these loci need not precede LOH of the chromosome 3p loci. We found a significant association between LOH of the VHL (3p25) locus and LOH of any chromosome 17 marker (P = 0.005), suggesting that there may be an important relationship, in the tumorigenesis of epithelial ovarian cancer, between a gene at 3p25 and a gene located on chromosome 17. Our results indicate that inactivation of p53 by somatic mutation is unlikely to be a prerequisite to chromosome 3p LOH, because we found no significant association between mutations in TP53 and LOH of the three chromosome 3p loci. The frequency of LOH at the FHIT locus at 3p14 increased significantly with advancing age at diagnosis (P = 0.018), as did the frequency of somatic TP53 mutations (P = 0.008).     

Frequent loss of heterozygosity on chromosomes Xp and 13q in human ovarian cancer.

Loss of heterozygosity (LOH) was examined at 27 loci on chromosomes 3p, 6q, 11p, 13q, 17 and X in 42 human ovarian tumors. LOH was detected in 12 of 26 (46%) and 5 of 12 (42%) informative cases at 2 chromosome 13q loci, D13S32 and D13S34 respectively. On chromosome Xp, tumor-specific allele loss was observed in 9 out of 15 informative cases (60%) at the ornithine transcarbamylase (OTC) gene locus. Examination of 12 additional Xp and 13q loci has mapped the common deletion regions to Xp21.1-->p11.4 and 13q33-->q34. The observation of significant LOH on Xp represents a strong indication of genetic changes in the X chromosome in a human malignancy. The allele losses on 13q which have been reported for other cancers suggest that chromosome 13, in addition to the retinoblastoma gene, may contain other growth-regulating gene(s) important in the development of several tumor types, including ovarian malignancies.     

Allelic imbalance and mutations of the PTEN gene in ovarian cancer

The PTEN/MMAC1/TEP1 tumor-suppressor gene, which maps to chromosome 10q23.3, is mutated and homozygously deleted in a variety of human tumors, including endometrioid-type ovarian tumors. We examined 33 primary ovarian cancers and 3 ovarian borderline tumors for allelic imbalance (AI) of the 10q23.3 region using 5 polymorphic markers, including an insertion/deletion-type polymorphic marker identified in intron 4 of the PTEN gene. AI at one or more loci was detected in 12 of 31 (39%) informative ovarian cancers and none of 3 ovarian borderline tumors. The commonly deleted region was mapped between the D10S215 and D10S541 loci, including the PTEN locus. Moreover, the incidence of AI at the PTEN locus (38%) was the highest among the 5 loci examined. Therefore, we searched for mutations in the entire coding region of the PTEN gene by PCR-SSCP and sequencing analyses in these tumors and 7 ovarian cancer cell lines. Mutations were detected in 3 of the 33 (9%) ovarian cancers: 2 cases with double mutations and 1 case with a mutation on 1 allele accompanied by deletions on both alleles in the poly T tract preceding the splice acceptor site in intron 7. An intragenic deletion was detected in 1 of the 7 (14%) ovarian cancer cell lines. PTEN mutations were detected not only in the endometrioid type but also in the serous and mucinous types of ovarian cancer. However, PTEN was not mutated in the 12 tumors that showed AI of the PTEN locus. Our results suggest that the PTEN gene plays an important role in the development of a subset but diverse histological types of ovarian tumors. However, it is possible that another tumor-suppressor gene in the close vicinity of the PTEN gene is also inactivated by AI of the 10q23.3 region.     

Allelotyping defines minimal imbalance at chromosomal region 17q25 in non-serous epithelial ovarian cancers

Allelic deletions of multiple chromosome 17q loci in sporadic ovarian cancer of epithelial origin suggest that inactivation of tumor suppressor gene(s) in these regions may be important for ovarian tumorigenesis. To further define the pattern of allelic imbalance in epithelial ovarian tumors of different histologies, a PCR-based assay was used to assess loss of heterozygosity (LOH) of polymorphic markers representative of TP53, BRCA1, NME1 and GH1, and region 17q23-25. LOH was observed for at least one marker in 68% of malignant tumors (n=60) and in 18% tumors of borderline malignancy (n=11), but not in benign tumors (n=5). The highest frequency of LOH in malignant tumors (64%) was observed with D17S801 on 17q25. Ten of 39 malignant ovarian tumors displaying LOH of at least one 17q marker, displayed a LOH pattern enabling the determination of a minimal region of overlapping deletion defined by D17S795 and D17S801. One borderline tumor also displayed an interstitial LOH pattern that overlapped this 17q25 minimal region of deletion. The histologies of malignant tumors displaying a pattern indicative of interstitial 17q deletions were of the endometrioid, clear cell and mucinous epithelial types. As the minimal region of overlap defined by these tumors overlap regions deleted in malignant tumors of all histologic types, and in a tumor of borderline malignancy, the 17q25-tumor suppressor may be implicated in the development of all types of epithelial ovarian tumors.     

Frequent loss of heterozygosity at telomeric loci on 22q in sporadic colorectal cancers

To date, several tumor-suppressor genes responsible for the tumorigenesis of colorectal cancer have been identified. However, studies of loss of heterozygosity (LOH) have suggested several chromosomal regions which may contain additional tumor-suppressor genes for colorectal cancer. To determine the extent and variation of allelic loss on 22q, on which LOH has been frequently observed, a total of 68 sporadic colorectal cancers was examined for LOH on the chromosome arm by means of 16 polymorphic DNA markers. LOH was observed in 28 tumors (41 %), of which 9 showed LOH at all informative loci. The remaining 19 tumors showed variable patterns of partial loss on 22q, delimiting the smallest region of overlap (SRO) between D22S90 and D22S94. Moreover, LOH within the SRO correlated with a progression in terms of Dukes' stages. These results suggest that an additional tumor-suppressor gene for colorectal cancer may exist on 22q distally to the NF2 locus and that inactivation of the gene may possibly play a role in the progression or metastasis of colorectal cancers. © 1995 Wiley-Liss, Inc.     

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.     

Loss of two new loci on chromosome 8 (8p23 and 8q12-13) in human prostate cancer

Inactivation of tumor suppressor genes due to allelic loss is thought to be an important mechanism of gene alterations in prostatic carcinogenesis. Loss of sequences on the short arm of chromosome 8 (8p) has been reported in human cancers, especially of 8p22 and 8p12-21 in prostate cancer. By using PCR analysis of polymorphic microsatellite repeat markers at four 8p loci and three 8q loci in 60 tumors, we observed deletion of sequences at two other deletion domains (8p23, and 8q12-13). There was loss in 51 of 60 cases (85%) with at least one marker. Four distinct regions of loss detected were: i) at 8p23, at locus D8S262; ii) at 8p22, on locus D8S259; iii) at 8p12, on loci D8S255 and D8S285; iv) at 8q12-13, on loci between D8S260 and D8S528. We found that 29% of the tumors showed LOH at 8p23; 19% LOH on 8p22; 54% had LOH at 8p12; and 48% had LOH at 8q12-13. There was higher frequency of LOH at 3 or more loci in samples of T3 stage (62%) as compared to T2 stage (13.3%) which suggests higher incidence of LOH in advanced stage of prostate cancer. We report deletion of two novel loci at 8p23 and 8q12-13, these regions may contain putative tumor suppressor genes in prostate cancer.     

Sublocalization of smallest common regions of deletion on chromosome 17q12-q23 in sporadic primary breast-tumors

Frequent loss of heterozygosity (LOH) on the long arm of chromosome 17 has been described in breast tumor DNAs by a number of groups, and recent fine genetic mapping and cloning of an inherited breast-ovarian cancer susceptibility locus (BRCA1) to a small region of 17q12-q21 has focused interest on this area. The absence of sporadic mutations in the BRCA1 gene in breast tumors studied so far suggests that there may be other tumor suppressor genes in the region involved in sporadic breast cancer. We studied 28 sporadic breast cancers with 14 highly polymorphic markers on chromosome 17 (2 on 17p and 12 on 17q). Most of the 17q markers are located within the 17q12-q23 region. We confirmed that 50% of tumors have deletions of at least one locus on chromosome arm 17q, and that half the deleted cases probably correspond to monosomies 17 or 17q. The other half correspond to a partial deletion on 17q and were used to identify 2 smallest common deleted regions (SCDR1 and SCDR2) on 17q12-q23. SCDR1 comprised the THRA1 gene, but not the 2 flanking loci tested (D17S250 and D17S800); while SCDR2 was defined by loci GIP and GH. BRCA1 was deleted in half the cases but it is outside the SCDR1. Moreover, breast tumors in young women frequently showed chromosome 17 alterations.     

Detection of frequent allelic loss on proximal chromosome 17q in sporadic breast carcinoma using microsatellite length polymorphisms.

Analyses of losses of heterozygosity and linkage studies have implicated a gene(s) on chromosome 17q in the genesis of sporadic and early-onset familial breast carcinomas, respectively. To define the critical region of 17q, we examined DNAs from a series of 20 sporadic breast carcinomas and corresponding blood samples for allelic losses of chromosome 17q using microsatellite length polymorphisms. With these highly informative markers (average heterozygosity, 0.73), we observed frequent deletions of 17q at several loci. We found that D17S250 was deleted in 50% (7 of 14), THRA1 in 79% (11 of 14), D17S579 in 59% (11 of 19), NME1 in 29% (5 of 17), MPO in 36% (4 of 11), and GH in 25% (4 of 16) in the tumor set examined. A common region of deletion was found that was flanked by D17S250 to D15S579. These markers have recently been localized to a 6-cM interval of proximal chromosome 17q in bands 17q11.2-q21 and map within the region of the early-onset familial breast cancer locus, implying that the same gene or genes may be involved in both sporadic and familial breast tumors. Thyroid hormone receptor alpha and retinoic acid receptor alpha are two potential candidate genes in this region.     

Deletion mapping of the long arm of chromosome 22 in human meningiomas

Cytogenetic and molecular genetic analyses have shown that a tumor-suppressor gene for human meningioma is located on the long arm of chromosome 22. Recently, somatic mutations of the NF2 gene have been identified in sporadic meningiomas. However, tumorigenesis of certain cases of meningioma cannot be fully explained by inactivation of the NF2 gene alone. Thus, to obtain some indication as to the existence of another tumorsuppressor gene, it seemed important to re-examine the loss of heterozygosity (LOH) on 22q in sporadic meningioma. A total of 46 sporadic meningiomas was examined for LOH at 20 loci on 22q. LOH was observed in 29 tumors (63%), of which 13 (28%) showed different patterns of a partial loss of 22q. However, the NF2 locus was retained in one tumor that lost a more distal part of 22q. Moreover, 27 of the 28 tumors which showed LOH at the NF2 locus also lost alleles at more telomeric loci. These results raise the possibility that another tumor-suppressor gene for meningioma may exist on 22q and that its localization may be distal to the D22S102 locus. © 1995 Wiley-Liss, Inc.     

Evidence for two distinct tumor-suppressor gene loci on the long arm of chromosome 11 in human oral cancer

Loss of heterozygosity (LOH) on human chromosome 11 has been reported in a variety of human cancers. To search for the existence of tumor-suppressor gene(s) associated with oral squamous cell carcinoma (SCC) on chromosome 11, we have performed high-resolution deletion mapping in 31 patients with oral SCC using 22 microsatellite markers for this chromosomal region. LOH was observed in 14 of 25 cases (56.0%) that were informative with at least one locus. Most allelic deletions detected in our study were specific to the long arm of the chromosome. Furthermore, the data presented here show 2 distinct, commonly deleted regions. The first region, with frequent LOH, was restricted between markers D11S939 and D11S924 separated by 3 centimorgans (cM) on chromosome 11q23. The second region of common deletion was identified between markers D115912 and D11S910, separated by 7 cM at 11q25. Our results suggest that at least 2 tumor-suppressor genes involved in the development of oral SCC are present on the long arm of chromosome II. © 1996 Wiley-Liss, Inc.     

Primary cervical carcinomas show 2 common regions of deletion at 3P, 1 within the FHIT gene: evaluation of allelic imbalance at FHIT, RB1 and TP53 in relation to survival

Chromosome arm 3p is re-arranged in many tumor types, including cervical carcinomas. Putative tumor-suppressor genes on 3p have been proposed, including the FHIT gene, which maps to chromosome band 3p14.2. We have analyzed 79 primary cervical carcinomas for allelic imbalance (AI) at 17 chromosome 3 loci, including 3 within the FHIT gene. Expression of the FHIT gene was evaluated after immunohistochemistry with an antibody against the pFHIT protein. Previously determined human papillomavirus status, defined after in situ hybridization, showed type 16 or 18 in 56/77 tumors. Tumors were also analyzed for AI at loci within the RB1 (chromosome band 13q14.2) and the TP53 (17p13) genes for AI. AI was found at 1 or more 3p loci in 50/79 tumors, at frequencies ranging from 30% to 52% at the individual loci. Two smallest regions of overlapping deletion (SROs) were found, 1 including parts of the FHIT gene (SRO flanked by D3S1481 and D3S1313) and another more distal SRO between D3S32 and D3S1286. FHIT protein expression was reduced in 57/69 (83%) tumors but not associated with AI at FHIT loci (p = 0.56). AI was found in TP53 and RB1 in 18% and 29% of the samples, respectively. Relapse-free survival was associated with AI in the TP53 gene in both a univariate (p = 0.0003) and a multivariate (p = 0.004) analysis. This study confirms a high frequency of AI at chromosome arm 3p in primary cervical carcinomas. The AI results and the reduced FHIT protein staining indicate that FHIT alterations are important in cervical carcinogenesis.     

Allelic loss of the PTEN region (10q23) in breast carcinomas of poor pathophenotype

Loss of heterozygosity (LOH) in loci of the 10q23 region that harbor the PTEN gene and mutations in the sequence of this gene have been found in several primary human tumors including breast carcinomas, suggesting that this gene could be implicated in their pathogenesis. We investigated allelic losses in microsatellites of the 10q23 region, and their correlations with nine pathologic parameters in 105 breast carcinomas. The LOH analysis was performcd by amplifying DNA by PCR, using five markers of the 10q23 region (D10S1687, D10S541, D10S2491, D10S583 and D10S571). LOH in at least one marker of the PTEN region was found in 29.5% of tumors. The statistical comparison between carcinomas with and without LOH in terms of the pathologic parameters showed significant differences in age (p=0.03), lymph node metastases (p=0.02), and higher histological grade (p=0.02); a trend toward significance was found for progesterone receptors (p=0.05). LOH in an individual marker and statistically significant relationships to tumor characteristics were observed at locus D10S541 for lymph node metastases (p=0.04), at D10S2491 (intragenic to the PTEN gene) for lymph node metastases (p=0.02), and at D10S583 for progesterone receptors (p=0.01) and for high grade (p=0.03). These results suggest the PTEN gene, or other genes of the 10q23 region, could be functionally related to breast cancer, probably influencing the development of histological features associated with poor prognosis.     

Distinct regions of frequent loss of heterozygosity of chromosome 5p and 5q in human esophageal cancer

Loss of heterozygosity (LOH) studies reported thus far suggest that tumor suppressor loci on chromosome 5q are important in esophageal cancer (EC) while little is known about the involvement of chromosome 5p. To investigate the potential existence of tumor suppressor gene(s) on chromosome 5 contributing to the development of EC, we performed LOH studies using a total of 24 polymorphic markers spanning the entire chromosome 5. Seventy primary esophageal cancers were microdissected and allelic deletions were detected by polymerase chain reaction (PCR)-single strand conformation polymorphism or by microsatellite analysis. LOH was observed in at least 1 of the loci in 47 of 70 (67%) esophageal tumors. Initially, 40 tumors [24 squamous cell carcinomas (SCC) and 16 adenocarcinomas (ADC)], each with matched histologically normal esophageal mucosa, were analyzed at 15 marker loci on 5p and 5q. A novel locus, D5S667 on 5p15.2, exhibited the highest frequency of LOH (44%) in these tumors along with another previously reported region of frequent deletion, irf-1 (5q31.1). In a series of 30 additional EC tumors (11 SCC and 19 ADC), a detailed LOH analysis of chromosome 5p15.2 region was conducted using 10 additional polymorphic markers, which mapped the frequently deleted region within 1 cM. Overall, LOH at the D5S667 locus was observed more frequently in SCC than in ADC (62% vs. 23%, p = 0.01). This significant rate of LOH of a distinct region of chromosome 5p implicates the existence of a putative tumor suppressor gene locus involved in EC. Int. J. Cancer 78:600–605, 1998. © 1998 Wiley-Liss, Inc.     

Comprehensive allelotype study of ovarian tumors of low malignant potential: potential differences in pathways between tumors with and without genetic predisposition to invasive carcinoma.

Ovarian tumors of low malignant potential (LMP) are intermediate between adenomas and ovarian carcinomas (OC); however, the relevance of LMP to ovarian carcinogenesis is not clear. We performed a comparative analysis of allelotypes in 50 cases of LMP (42 mucinous and 8 serous) and 23 cases of OC (15 mucinous and 8 serous) to investigate any differences in genetic changes. Analysis of loss of heterozygosity (LOH) using 25 microsatellite markers reportedly associated with OC revealed that the total LOH frequency at each marker was significantly lower in LMP than in OC (p < 0.01). However, 9 (36%) loci showed higher LOH frequency in mucinous LMP than in mucinous OC. A genome-wide scan for LOH using 91 microsatellite markers and fine mapping revealed that LOH at D7S1805 (7q35) is characteristic of mucinous LMP (19.4% in mucinous LMP, 8.3% in mucinous OC). We further studied LOH in 3 cases of mucinous OC that were accompanied by mucinous LMP lesions. In 2 cases, LOH frequency was higher in the carcinoma portion than in the morphologically LMP portion. The other case showed microsatellite instability in the morphologically LMP portion and LOH in the carcinoma portion. Our results suggest the presence of an LMP-to-OC developmental sequence and the existence of a subset of LMP that does not develop into OC in the mucinous subtype of ovarian tumors.     

Frequent allelic loss on chromosome 9 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy worldwide and highly associated with chronic virus-B or -C infection and cirrhosis. Molecular studies have shown high frequency of loss of heterozygosity (LOH) in some specific chromosome regions, but LOH on chromosome 9 in HCC has not been thoroughly investigated. In our investigation of chromosome 9 with 19 polymerase-chain-reaction (PCR)-based polymorphic microsatellite markers, 30 of 48 HCC tissue samples (63%) had LOH, and a distinct common deletion region and a region of loss were identified. The first region was located at the 9p21 region and the minimal deletion region was located between loci D9S1747 and D9S1748. This is a region of approximately 200 kb which includes the p16 tumor-suppressor gene. A region of loss was located on 9p13 to 9q33. The putative tumor-suppressor gene for nevoid-basal-cell-carcinoma syndrome (NBCCS) at 9q22.3 resides within this region. In addition to LOH, 4 HCC cases showed possible homozygous deletions at 9p21 with markers D9S1748, D9S1752 and D9S171 by multiplex PCR analysis. In 3 cases, the minimal region of possible homozygous deletion was approximately 300 kb and was defined between markers D9S1747 and D9S1752. Since this deletion region includes both the p15 and the p16 tumor-suppressor genes, these genes were possibly inactivated by homozygous deletion in HCC. In addition, a second region of possible homozygous deletion was present on the centromeric side of 9p21. However, these changes are not associated with age, gender, size or tumor-cell differentiation. Our data also suggest that inactivation of the p16 and the p15 genes and the possibility of other unknown tumor-suppressor genes located on these defined deleted regions of chromosome 9 may be involved in the pathogenesis of HCC.     

Loss of heterozygosity on chromosome arms 3p and 6q in microdissected adenocarcinomas of the uterine cervix and adenocarcinoma in situ

BACKGROUND: Despite the increasing frequency of adenocarcinomas of the uterine cervix, little is known regarding inactivation of tumor suppressor genes (TSGs) in this tumor type. The authors analyzed loss of heterozygosity (LOH) in 36 carcinomas of the cervix with glandular differentiation, and 5 adenocarcinoma in situ in 40 patients. METHODS: The authors analyzed samples using laser capture microdissection from archival material and DNA amplified with microsatellite markers on the following loci: 3p14.2 (D3S1234, D3S1300), 3p21.3 (D3S1029, D3S1447), 3p22-24 (D3S1537, D3S1351), 6q21-23.3 (D6S250), 6q25.1 (ESR), 6q25.2 (D6S255), 8p21 (D8S136, D8S1820), 13q12.3 (D13S220, D13S267), 17q21 (D17S579, D17S855). Eight additional markers spanning the short arm of chromosome 3 (3p12-p25) and six spanning the long arm of chromosome 6 (6q11-q27) were studied in the cases showing LOH to further define the deletion intervals. RESULTS: The frequency of allelic loss in cancers was chromosome 3p: 49% (p14.2: 35%, p21.3: 23%, p22-24: 41%), 6q: 48% (q21-23.1: 39%, q25.1: 45%, q25.2: 7%), 13q: 22%, 17q: 6%, and 8p: 18%. On chromosome arm 3p, the authors' data suggest at least two discrete areas of deletion: a proximal area between markers D3S1234 (p12) and D3S1766 (p14.2-14.3), and a second distal interval, telomeric from marker D3S4623 (p21.3). On chromosome 6q, the deletion area is between marker D6S300 (q22) and D6S255 (q25.2). Two of five preneoplastic lesions showed LOH on chromosome arm 3p, and two five showed allelic loss on chromosome arm on 6q, suggesting the genes might be inactivated early in cervical tumorigenesis. CONCLUSIONS: The authors have identified three chromosomal regions that may harbor TSGs involved in the development/progression of adenocarcinomas of the uterine cervix, 3p12-14.2, 3p21.3-pter, and 6q22-25.2. Deletions also were detected in adenocarcinoma in situ, suggesting the genes may be inactivated early in cervical tumorigenesis.