胃癌中PTEN异常表达与围基因微卫星的杂合性缺失

目的　观察胃癌中PTEN基因异常表达与围基因微卫星的杂合性缺失 (LOH) ,探讨其在胃癌演进中的作用。方法　利用PCR SSCP检测进展期胃癌中PTEN围基因微卫星位点 (D10S5 4 1、D10S5 83、D10S16 87)的LOH ;采用RT PCR和免疫组化检测正常胃黏膜和胃癌中PTEN基因mRNA和蛋白表达 ;比较PTEN表达与淋巴结转移的关系 ;分析PTENmRNA表达与微卫星位点LOH及PTEN蛋白表达的关系。结果　进展期胃癌中D10S5 4 1、D10S5 83及D10S16 87微卫星位点LOH总的发生频率为2 8.6 % ;正常胃黏膜、早期胃癌和进展期胃癌的PTENmRNA阳性率分别为 80 .4 %、4 5 .5 %和 32 .1% ,其蛋白阳性率分别为 78.6 %、36 .4 %和 2 8.6 % ;早期和进展期胃癌中 ,PTENmRNA和蛋白阳性率低于正常胃黏膜 (P <0 .0 5 ) ;进展期胃癌中 ,PTENmRNA表达与其围基因微卫星LOH呈正相关 (Pearson相关系数 =0 .2 6 6 ) ;PTENmRNA与蛋白表达具有显著的一致性 (P <0 .0 5 ) ;PTENmRNA和蛋白表达与进展期胃癌淋巴结转移有关 (P <0 .0 5 )。结论　PTEN基因在胃癌发展不同阶段表达下调 ,并与其围基因微卫星LOH密切相关 ,微卫星LOH可能是其低表达的分子基础之一 ,PTEN基因表达异常与围基因微卫星LOH在胃癌发生和演进中具有重要意义。     

Loss of heterozygosity in BRCA1 and BRCA2 markers and high‐grade malignancy in breast cancer

Loss of heterozygosity (LOH) in loci of the 17q21 and 13q1213 regions can collaborate in the inactivation of BRCA1, BRCA2, and possibly other genes implicated in the pathogenesis of breast carcinomas. We investigate allelic losses in microsatellites of the BRCA1 and BRCA2 regions, and their correlations with seven pathologic parameters in 140 breast carcinomas. Those cases showing LOH in the region of the RB gene, 13q14, were excluded from the study. The LOH analysis was performed by amplifying DNA by PCR, using four markers of the 17q21 region (D17S856, D17S855, D17S1323, and D17S1327) and four markers of the 13q1213 region (D13S290, D13S260, D13S310, and D13S267). LOH in the BRCA1 region was found in 47% of tumors, correlating significantly with estrogen receptor content (p = 0.025), progesterone receptors (p = 0.004), higher grade (p = 0.0008), peritumoral vessel invasion (p = 0.001), and lymph node metastases (p = 0.002). When we excluded the cases with LOH in the BRCA2 region and those not informative for it, the significance disappeared. In the BRCA2 region, a rate of LOH of 51% was found; it correlated significantly with estrogen receptor content (p = 0.002), progesterone receptors (p =0.03), peritumoral vessel invasion (p = 0.005), higher grade (p =0.002), and lymph node metastases (p = 0.001). When cases with BRCA1 losses and those not informative were excluded, again the significance disappeared. Concomitant losses in the BRCA1 and BRCA2 regions were found in 32% of cases, correlating significantly with lymph node metastases (p = 0.0002), estrogen receptor content (p = 0.003), progesterone receptors (p = 0.001), histologic grade (p =0.01), and peritumoral vessel invasion (p = 0.0004). These results suggest that concomitant losses in both regions could have a functional effect, influencing the presence of a poor tumor pathophenotype in breast carcinomas.     

Analysis of Genetic Alterations Related to the Development and Progression of Breast Carcinoma

To study genetic alterations related to the development and/or progression of breast carcinoma, we examined amplification of the ERBB2, INT2, and MYC genes, as well as loss of heterozygosity (LOH) at loci on 11p, 16q, 17p ( D17S5 and TP53 ), 17q ( D17S74 and NME1 ), and 18q by restriction fragment length polymorphism analysis. The subjects were 26 patients with small breast carcinomas (≦2 cm) and 88 patients with larger breast carcinomas (2 to < 5 cm). All patients were free of distant metastasis. As tumor diameter increased, the frequency of oncogene amplification and LOH at all loci except D17S5 increased. However, there was no relationship between tumor diameter and amplification of specific oncogenes or allelic loss at specific loci. LOH at D17S5 was detected in 40% of small breast carcinomas (≦2 cm) and 43% of larger breast carcinomas (2 to < 5 cm). There was a significant correlation of LOH at D17S5 with INT2 amplification or with LOH on 11p, 16q, and 18q. These findings suggest that LOH at D17S5 may be involved in the early stage of breast carcinoma development, while INT2 amplification and LOH at 11p, 16q, and 18q appear to be genetic alterations that occur with tumor progression. In addition, as lymph node metastases were significantly related to amplification of the ERBB2 and MYC genes, and LOH of the NME1 gene, these genetic alterations may play a role in the mechanism of lymph node metastases.     

Loss of heterozygosity on chromosome 10q23 and mutation of the phosphatase and tensin homolog deleted from chromosome 10 tumor suppressor gene in Korean hepatocellular carcinoma patients

Loss of heterozygosity (LOH) in the 10q23 chromosomal region was analyzed in 18 tissue samples from Korean hepatocellular carcinoma (HCC) patients. LOH at the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) region (D10S215, AFMa086wg9 and D10S541) was found in 8 of the 18 (44.4%) HCCs. LOH (20%) and microsatellite instability (26.7%) were also frequently found at the D10S2177 locus, which is located on the telomere side of the PTEN region. LOH was found in other loci, such as AFM280we1 and D10S2281. The presence of LOH in regions other than the PTEN region on chromosome 10q23 suggested the presence of additional tumor suppressor gene(s). PTEN mutation was found in only a subset of HCCs: A single base insertion at the end of the 5'-end splice signal (AG-GUAAGUU) in intron 5 and a silent mutation in exon 6 (codon 188, CTG-Val to CTA). Our data collectively suggest that the genetic alterations of chromosome 10q23, including the PTEN gene, could be important in hepatocarcinogenesis in the Korean population.     

Clonal origin of lymph node metastases in bladder carcinoma

BACKGROUND: Evidence of genetic heterogeneity within urothelial carcinomas of the bladder has raised questions about the clonal origin of urothelial carcinoma and its metastases. High-grade urothelial carcinoma of the bladder frequently metastasizes to multiple regional lymph nodes in the pelvis. Whether or not these multiple lymph node metastases originate from the same tumor clone is uncertain. Molecular analysis of microsatellite alterations and X-chromosome inactivation status of distinct tumor cell populations from the same patient may further our understanding of the genetic basis of carcinoma progression and metastasis. METHODS: The authors examined 24 patients who underwent radical cystectomy for urothelial carcinoma. All patients had multiple (from two to four) lymph node metastases. Genomic DNA samples were prepared from formalin fixed, paraffin embedded tissue sections using laser-assisted microdissection. Loss of heterozygosity (LOH) assays for 3 microsatellite polymorphic markers on chromosome 9p21 (D9S171, region of putative tumor suppressor gene p16), 9q32 (D9S177, putative tumor suppressor gene involved in urothelial carcinoma tumorigenesis), and 17p13 (TP53, the p53 locus) were performed. In addition, X-chromosome inactivation analysis was performed in primary tumors and metastases from 10 female patients. RESULTS: In total, 79 tumors were analyzed. The overall frequency of allelic loss was 67% (16 of 24 tumors) in the primary urothelial carcinomas and 79% (19 of 24 tumors) in the metastatic carcinomas. The primary urothelial carcinoma showed LOH at the D9S171, D9S177, and TP53 loci in 39% (9 of 23 tumors), 30% (6 of 20 tumors), and 30% (7 of 23 tumors) of informative samples, respectively. LOH in > or = 1 lymph node metastases was seen at the D9S171, D9S177, and TP53 loci in 35% (8 of 23 tumors), 45% (9 of 20 tumors), and 48% (11 of 23 tumors) of informative samples, respectively. Eleven tumors demonstrated identical allelic loss patterns at all DNA loci both in the primary carcinoma and in all corresponding lymph node metastases. Three tumors showed allelic loss in the metastatic carcinoma but not in its matched primary carcinoma. Six tumors demonstrated a different LOH pattern in each of its lymph node metastases. Clonality analysis showed the same pattern of nonrandom X-chromosome inactivation both in the primary urothelial carcinoma and in all of the lymph node metastases in five of nine informative tumors studied. Four tumors showed a random pattern of X-chromosome inactivation in both the primary carcinoma and in the metastases. CONCLUSIONS: LOH and X-chromosome inactivation assays showed that multiple lymph node metastases and matched primary urothelial carcinomas of the bladder had the same clonal origin, suggesting that the capability for metastasis often arises in only a single clonal population in the primary tumor. The variable LOH patterns observed in some of the tumors likely reflect genetic divergence during the clonal evolution of urothelial carcinoma.     

Analysis of the 10q23 chromosomal region and the PTEN gene in human sporadic breast carcinoma

We examined a panel of sporadic breast carcinomas for loss of heterozygosity (LOH) in a 10-cM interval on chromosome 10 known to encompass the PTEN gene. We detected allele loss in 27 of 70 breast tumour DNAs. Fifteen of these showed loss limited to a subregion of the area studied. The most commonly deleted region was flanked by D10S215 and D10S541 and encompasses the PTEN locus. We used a combination of denaturing gradient gel electrophoresis and single-strand conformation polymorphism analyses to investigate the presence of PTEN mutations in tumours with LOH in this region. We did not detect mutations of PTEN in any of these tumours. Our data show that, in sporadic breast carcinoma, loss of heterozygosity of the PTEN locus is frequent, but mutation of PTEN is not. These results are consistent with loss of another unidentified tumour suppressor in this region in sporadic breast carcinoma.     

Allelic loss of 10q23, the PTEN tumour suppressor gene locus, in Barrett's oesophagus-associated adenocarcinoma

PTEN is a putative tumour suppressor gene located on chromosome band 10q23. Mutations in PTEN have been identified in numerous human malignancies, including cancers of the brain, endometrium, ovary, and prostate. In this study, we screened 80 Barrett's oesophagus-associated adenocarcinomas (BOAd) for loss of heterozygosity (LOH) at 10q23, using the microsatellite markers D10S541, D10S219, and D10S551. Tumours demonstrating LOH were then screened for the presence or absence of PTEN mutations. LOH at one or more loci was identified in 17/80 (21%) cases. In none of these cases did we detect mutations in PTEN. The presence of LOH did not correlate with patient age, tumour stage, degree of differentiation, presence of perineural or vascular invasion, or overall survival. We conclude that LOH at chromosome 10q23 is uncommon in BOAd, is not associated with mutations in the PTEN tumour suppressor gene, and does not correlate with the clinical or pathologic features of these tumours. It is possible that PTEN is inactivated through other mechanisms in BOAd.     

Exclusion of a major role for the PTEN tumour-suppressor gene in breast carcinomas

PTEN is a novel tumour-suppressor gene located on chromosomal band 10q23.3. This region displays frequent loss of heterozygosity (LOH) in a variety of human neoplasms including breast carcinomas. The detection of PTEN mutations in Cowden disease and in breast carcinoma cell lines suggests that PTEN may be involved in mammary carcinogenesis. We here report a mutational analysis of tumour specimens from 103 primary breast carcinomas and constitutive DNA from 25 breast cancer families. The entire coding region of PTEN was screened by single-strand conformation polymorphism (SSCP) analysis and direct sequencing using intron-based primers. No germline mutations could be identified in the breast cancer families and only one sporadic carcinoma carried a PTEN mutation at one allele. In addition, all sporadic tumours were analysed for homozygous deletions by differential polymerase chain reaction (PCR) and for allelic loss using the microsatellite markers D10S215, D10S564 and D10S573. No homozygous deletions were detected and only 10 out of 94 informative tumours showed allelic loss in the PTEN region. These results suggest that PTEN does not play a major role in breast cancer formation.     

A novel region of deletion on 13q33-q34 in esophageal squamous cell carcinoma

Chromosome 13 presents frequent allelic loss in esophageal squamous cell carcinomas (ESCC). However, no ESCC suppressor gene has been identified from this chromosome. To define common deletion regions that possibly contain the ESCC suppressor gene(s), we performed a mapping of allelic loss in 50 esophageal squamous cell carcinomas using a panel of 25 microsatellite markers on chromosome 13q21-qter, which has rarely been studied for allelic loss. Loss of heterozygosity (LOH) with high frequencies (> or = 50%) was observed at markers D13S1494, D13S1323, D13S248, D13S1315, D13S285, and D13S1295, in which the peak LOH (69.2%) was at locus D13S248. Seven cases presented LOH at three consecutive markers D13S248, D13S1315 and D13S285, 4 of which also displayed LOH at another adjacent marker D13S1295. This overlapping region of deletion covers an interval of 6.36 Mb at 13q33.1-q34, whose deletion has not previously been reported in ESCC. Tumors of grade II showed significantly more frequent LOH at D13S248 than those of grade I. A significantly higher frequency of allelic loss at D13S152 was also found in tumors with lymph node metastasis compared to those without lymph node metastasis. The present study defined a novel region of allelic loss in 13q33-q34. LOH at D13S248 and D13S152 are associated with higher tumor grade and metastasis, respectively.     

Refined deletion mapping in sporadic breast cancer at chromosomal region 8p12-p21 and association with clinicopathological parameters

We have further refined the loss of heterozygosity (LOH) pattern on the human chromosomal region 8p12-p21 using 15 well characterised microsatellite markers in a panel of 50 breast carcinomas. The allelic loss pattern of these tumours suggests the presence of five commonly deleted regions on 8p12-p21. The most commonly deleted region was located between markers D8S1734 and D81989, spanning a distance of approximately 3 cM and reaching 56% LOH at locus NEFL. LOH at 8p12-p21 was significantly correlated with large tumour size (T>5 cm). Patients with the age at diagnosis of breast cancer between 45 and 55 years showed significantly more LOH than patients older than 55 years or younger than 45 years. No correlation was observed between 8p12-p21 alterations and histological tumour type, grade and the presence of lymph node metastases.     

Somatic Mutations of the PTEN/MMAC1 Gene in Fifteen Japanese Endometrial Cancers: Evidence for Inactivation of Both Alleles

Loss of heterozygosity (LOH) of chromosome 10q is observed in approximately 40% of endometrial cancers. Mutations in PTEN/MMAC1 , a gene recently isolated from the 10q23 region, are responsible for two dominantly inherited neoplastic syndromes, Cowden disease and Bannayan-Zonana syndrome. Somatic mutations of this gene have also been detected in sporadic cancers of the brain, prostate and breast. To investigate the potential role of this putative tumor suppressor gene in endometrial carcinogenesis as well, we examined 46 primary endometrial cancers for LOH at the 10q23 region, and for mutations in the entire coding region and exon-intron boundaries of the PTEN/MMAC1 gene. LOH was identified in half of the 38 informative cases, and subtle somatic mutations were detected in 15 tumors (33%). Our results suggest that of the genes studied so far in endometrial carcinomas, PTEN/MMAC1 is the most commonly mutated one, and that inactivation of both copies by allelic loss and/or mutation, a pattern that defines genes as "tumor suppressors,'contributes to tumorigenesis in endometrial cancers.     

Refinement of the LOH region 1 at 11q23.1 deleted in human breast carcinomas and sublocalization of 11 expressed sequence tags within the refined region

Loss of constitutive heterozygosity at 11q23 has been detected in various human solid tumors. Here, we described the analysis of a series of normal and tumor pairs from 110 breast carcinomas for the presence of loss of heterozygosity at 11q23 loci. The overall frequency of LOH was 48%, confirming the importance of deletions at 11q23 in breast tumorigenesis. Previously, we have identified two independent regions of LOH at 11q23, the LOH region 1 at 11q23.1 and the LOH region 2 at 11q23.3. The most telomeric region was recently refined between loci D11S1345 and D11S1316, a region of about 1 Mb. However, the LOH region 1, most centromeric, was still not finely refined: the boundaries were defined by loci D11S2000 and D11S897, separated by about 8 Mb. Here, we refined its boundaries between loci D11S1347 and D11S927, a region of about 2 Mb. We have mapped 11 expressed sequence tags (ESTs) within this region and excluded another 20. This study represents a further step toward the identification of the putative tumor suppressor gene found within the LOH region 1 at 11q23.1.     

PTEN/MMAC1 Mutation and Frequent Loss of Heterozygosity Identified in Chromosome 10q in a Subset of Hepatocellular Carcinomas

Frequent allelic losses on chromosome 10q have been reported in several types of cancers, suggesting the presence of a putative tumor suppressor gene(s) on the chromosomal arm. We examined loss of heterozygosity (LOH) on chromosome 10q in 37 hepatocellular carcinomas (HCC) using eleven dinucleotide microsatellite markers, spanning the entire chromosome arm of 10q. Twelve (32%) out of 37 informative cases showed allelic losses of at least one locus on 10q and eight tumors showed a partial deletion of 10q. Analysis of deletion mapping of these eight cases identified two commonly deleted regions within the distal part of 10q (10q24-q26), a 20-cM interval flanked by D10S597 and D10S216 and a 24-cM interval flanked by D10S216 and D10S590. Moreover, we detected a somatic missense mutation (Met→Val) of a candidate tumor suppressor gene PTEN/MMAC1, located at 10q23.3, in one HCC with LOH of 10q. Our findings indicated the presence of putative tumor suppressor gene(s) in the distal region of 10q that might be involved in the development and progression of HCC. Inactivation of PTEN/MMAC1 gene located outside the commonly deleted region of 10q might also play an important role in a subset of HCCs.     

PTEN / MMAC1 mutation and frequent loss of heterozygosity identified in chromosome 10q in a subset of hepatocellular carcinomas.

Frequent allelic losses on chromosome 10q have been reported in several types of cancers, suggesting the presence of a putative tumor suppressor gene(s) on the chromosomal arm. We examined loss of heterozygosity (LOH) on chromosome 10q in 37 hepatocellular carcinomas (HCC) using eleven dinucleotide microsatellite markers, spanning the entire chromosome arm of 10q. Twelve (32%) out of 37 informative cases showed allelic losses of at least one locus on 10q and eight tumors showed a partial deletion of 10q. Analysis of deletion mapping of these eight cases identified two commonly deleted regions within the distal part of 10q (10q24-q26), a 20-cM interval flanked by D10S597 and D10S216 and a 24-cM interval flanked by D10S216 and D10S590. Moreover, we detected a somatic missense mutation (Met --> Val) of a candidate tumor suppressor gene PTEN / MMAC1, located at 10q23.3, in one HCC with LOH of 10q. Our findings indicated the presence of putative tumor suppressor gene(s) in the distal region of 10q that might be involved in the development and progression of HCC. Inactivation of PTEN / MMAC1 gene located outside the commonly deleted region of 10q might also play an important role in a subset of HCCs.     

Accumulation of genetic alterations in brain metastases of sporadic breast carcinomas is associated with reduced survival after metastasis.

Tumor progression is characterized by stepwise accumulation of genetic alterations. To identify alterations associated with breast cancer metastasis, an analysis of comparative loss of heterozygosity (LOH) was performed on 38 primary sporadic breast carcinomas and 16 distant metastases. Two loci at 5q21 and 18q21 were chosen because of their reported increased deletion frequency in metastatic tumors. LOH at 17q21, 13q12-13, 17p13.1 and 11q22-23 was analyzed to determine whether there is a specific involvement of these breast cancer-associated gene loci in the metastatic process. Our data show that distant metastases are characterized by markedly increased LOH frequency at all loci examined. In both gene locus groups, significantly more distant metastases are affected by combined LOH. Furthermore, a significantly reduced postmetastatic survival time has been observed in patients with brain metastases affected by synchronous allelic loss at the four breast cancer-associated gene loci. Our results suggest that cumulative LOH of breast cancer-related gene loci is associated with a more aggressive phenotype of metastatic breast tumors.     

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.     

Correlation of loss of alleles on the short arms of chromosomes 11 and 17 with metastasis of primary breast cancer to lymph nodes.

To examine the role of loss of heterozygosity (LOH) during tumor development and/or progression, we looked for correlations between metastasis of breast cancer to a regional lymph node(s) and LOH of chromosomal arms 11p, 13q, 16q, 17p, and 17q, where frequent losses in primary tumors have been detected. No correlation between lymph node metastasis and LOH of chromosomes 13q, 16q, or 17q was observed. However, tumors showing LOH of chromosomes 11p (chi 2 = 10.82, P less than 0.01) and 17p (chi 2 = 6.78, P less than 0.01) revealed a significantly higher incidence of metastasis to a regional lymph node(s) than tumors without LOH on these chromosomal arms. Furthermore, only four of 30 (13%) patients with tumors that retained both 11p and 17p had metastasis to a regional lymph node(s), compared with 24 of 32 (75%) patients with tumors that had lost both 11p and 17p. Analysis of LOH with markers on chromosomes 11p and 17p in a large number of tumors indicated that the peritelomeric region of each of these chromosomal arms contains a tumor suppressor gene that may be associated with tumor progression, particularly metastasis to a regional lymph node(s).     

Lymph node metastasis is associated with allelic loss on chromosome 13q12-13 in esophageal squamous cell carcinoma.

Allelotype analysis of whole chromosomes showed that loss of heterozygosity (LOH) on 13q was exclusively associated with lymph node metastasis and poor prognosis in esophageal squamous cell carcinoma (ESC). To identify a locus responsible for lymph node metastasis, we performed fine deletion mapping on 13q by analyzing 60 ESCs with 18 polymorphic markers. Allelic loss was observed with at least one marker in 34 tumors (56.7%), and lymph node metastasis was significantly correlated with LOH (P = 0.0053). We found frequent loss at D13S260 (43.7%), D13S171 (38.6%), and D13S267 (43.6%) on 13q12-13. Among these markers, LOH at D13S171 showed a significant correlation with lymph node metastasis (P = 0.0441). Because these markers flank the BRCA2 gene, we intensively examined a mutation of the gene through all coding exons and exon-intron junctions by PCR-single-strand conformational polymorphism analysis under two different assays. We found only seven nucleotide substitutions as normal polymorphic changes; tumor-specific mutations were not detected, and loss of expression was not observed, indicating that the BRCA2 gene might not be a target of allelic loss in this region. Relatively frequent LOH was also found at the RB1 locus (34.7%), but a significant correlation with lymph node metastasis was not observed (P = 0.7430). Protein expression of RB1 was examined in 31 ESC cell lines, and loss of expression was infrequent (6.5%), indicating that inactivation of the RB1 gene might not be responsible for lymph node metastasis. Taken together, allelic loss at 13q12-13 of the primary ESC was closely associated with lymph node metastasis, and unidentified tumor suppressor gene(s) in this region might be involved.     

Loss of heterozygosity on 10q23.3 and mutation of the tumor suppressor gene PTEN in benign endometrial cyst of the ovary: possible sequence progression from benign endometrial cyst to endometrioid carcinoma and clear cell carcinoma of the ovary

Loss of heterozygosity (LOH) at locus 10q23.3 and mutation of the PTEN tumor suppressor gene occur frequently in both endometrial carcinoma and ovarian endometrioid carcinoma. To investigate the potential role of the PTEN gene in the carcinogenesis of ovarian endometrioid carcinoma and its related subtype, clear cell carcinoma, we examined 20 ovarian endometrioid carcinomas, 24 clear cell carcinomas, and 34 solitary endometrial cysts of the ovary for LOH at 10q23.3 and point mutations within the entire coding region of the PTEN gene. LOH was found in 8 of 19 ovarian endometrioid carcinomas (42.1%), 6 of 22 clear cell carcinomas (27.3%), and 13 of 23 solitary endometrial cysts (56.5%). In 5 endometrioid carcinomas synchronous with endometriosis, 3 cases displayed LOH events common to both the carcinoma and the endometriosis, 1 displayed an LOH event in only the carcinoma, and 1 displayed no LOH events in either lesion. In 7 clear cell carcinomas synchronous with endometriosis, 3 displayed LOH events common to both the carcinoma and the endometriosis, 1 displayed an LOH event in only the carcinoma, and 3 displayed no LOH events in either lesion. In no cases were there LOH events in the endometriosis only. Somatic mutations in the PTEN gene were identified in 4 of 20 ovarian endometrioid carcinomas (20.0%), 2 of 24 clear cell carcinomas (8.3%), and 7 of 34 solitary endometrial cysts (20.6%). These results indicate that inactivation of the PTEN tumor suppressor gene is an early event in the development of ovarian endometrioid carcinoma and clear cell carcinoma of the ovary.