PTEN mutations and microsatellite instability in complex atypical hyperplasia, a precursor lesion to uterine endometrioid carcinoma

The two most common types of genetic alterations yet identified in uterine endometrioid carcinoma (UEC) are PTEN mutations and microsatellite instability (MI). Furthermore, MI-positive UECs (defined as tumors with detectable alterations at two or more different microsatellite loci) are significantly more likely to contain PTEN mutations than are MI-negative UECs. To determine whether PTEN inactivation is a relatively early event in endometrial tumorigenesis, we evaluated complex atypical hyperplasia (CAH), the direct precursor to UEC, for the presence of PTEN mutations. Mutations were present in 3 of 11 (27%) CAHs with synchronous UEC and in 4 of 18 (22%) CAHs that were not associated with invasive carcinoma. One case with synchronous CAH and UEC contained a germ-line PTEN mutation. In addition, we evaluated the same series of CAHs for MI. We identified four MI-positive CAHs with synchronous UEC but did not detect the MI phenotype in any CAHs without associated invasive carcinoma. A PTEN-mutant (germ-line mutation) MI-negative CAH was synchronous with a PTEN-mutant MI-positive UEC. These results suggest that mutation of PTEN can be an early event in the pathogenesis of UEC and may precede the development of the MI phenotype in a subset of cases.

Multivariate analyses of DNA index, p62c-myc, and clinicopathological status of patients with ovarian cancer

AIM

To determine if either DNA index or p62c-myc is an independent prognostic variable in ovarian cancer.

METHODS

Multivariate and univariate analyses of the relation between DNA index, p62c-myc, FIGO stage, histological type, tumour grade, completeness of surgery, and patient survival in ovarian cancer were examined.

RESULTS

Multivariate analysis showed significant association of survival only with stage and grade. There was no relation between survival and DNA index.

CONCLUSIONS

DNA index is not an independent prognostic variable in ovarian cancer.

Frequent PTEN/MMAC mutations in endometrioid but not serous or mucinous epithelial ovarian tumors

Epithelial ovarian cancer comprises three major histological subtypes (serous, mucinous, and endometrioid), and it is becoming clear that the developmental pathways for these subtypes are fundamentally different. In particular, endometrioid ovarian cancers probably arise by the malignant transformation of ectopic endometrial implants called endometriosis and not the ovarian surface epithelium. The PTEN/MMAC gene on chromosome 10q23 is a tumor suppressor implicated in the pathogenesis of a wide variety of malignancies, but to date, somatic mutations in PTEN have not been identified in studies of predominantly serous ovarian cancers. In endometrial cancers, PTEN mutations are very common in tumors of the endometrioid type but have rarely been found in serous types, and we hypothesized that a similar histological subtype bias might be occurring in ovarian cancer. We have analyzed 81 ovarian tumors, including 34 endometrioid, 29 serous, 10 mucinous, and 8 clear cell tumors, for loss of heterozygosity (LOH) on 10q23 and for mutations in all 9 coding exons of PTEN. LOH was common among the endometrioid (43%) and serous (28%) tumors but was infrequent among the other histological subtypes. Somatic PTEN mutations were detected in seven (21%) of the endometrioid tumors, and in all informative cases, the mutation was accompanied by loss of the wild-type allele. One mucinous tumor without 10q23 LOH was shown to harbor two somatic PTEN mutations. In this tumor, the histological appearance of the mucinous areas was atypical, and the mucinous areas contained foci of endometrioid differentiation. The majority of tumors with PTEN mutations were grade 1 and/or stage 1, suggesting that inactivation of PTEN is an early event in ovarian tumorigenesis. No PTEN mutations were found among the serous or clear cell tumors. The identification of frequent somatic PTEN mutations in endometrioid ovarian tumors indicates that it plays a significant role in the etiology of this subtype. The absence of mutations in other histological subtypes is consistent with the hypothesis that epithelial ovarian cancers arise through distinct developmental pathways.

Frequent loss of chromosome 12 in human epithelial ovarian tumors: a chromosomal in situ hybridization study

The short arm isochromosome of chromosome 12 and trisomy 12 are well-established chromosomal alterations in human ovarian germ cell tumors. However, numerical aberrations of chromosome 12 in epithelial ovarian tumors (EOTs) are highly controversial; both trisomy 12 and monosomy 12 have been observed. We performed chromosomal in situ hybridization in paraffin-embedded and formalin-fixed tissue sections of 31 EOTs. Twenty-five EOTs could be evaluated statistically (2 mucinous, 11 serous, 5 endometrioid, 3 borderline, and 4 other epithelial-type tumors) to examine the copy number of chromosome 12 and 15. The frequency distribution of hybridization signals with alpha-satellite centromeric DNA probes for chromosome 15 revealed disomy in all cases. However, we found the loss of chromosome 12 in 16 of 25 tumor samples. No correlation was found between the presence of monosomy 12 and the clinical stage of the tumors. Frequent loss of chromosome 12 may indicate that this chromosome is involved in the tumorigenesis of EOTs. Further studies are needed to clarify whether loss of chromosome 12 is an early or late event in ovarian carcinogenesis.

Mutations in the beta-catenin gene (CTNNB1) in endometrioid ovarian carcinomas

Mutations of the beta-catenin gene (CTNNB1) have recently been implicated in the initiation of some colon carcinomas and melanomas. In these tumors, beta-catenin abnormally accumulates in the cell nuclei. In an ongoing immunohistochemical study of the cadherin-catenin complex protein expression in ovarian carcinomas, we observed beta-catenin in tumor cell nuclei in some cases; this prompted us to study whether or not this abnormal immunostaining pattern was due to mutation in the beta-catenin gene itself. This study examines beta-catenin immunohistochemical expression in 40 stage I and II ovarian borderline tumors and carcinomas of the most common histological types. Membrane expression was heterogeneous in all 40 cases. However, the cytoplasm and nucleus of five (one borderline tumor and four carcinomas) of the six endometrioid lesions contained beta-catenin expression. PCR and sequencing analyses of a 200-bp fragment of exon 3 of the CTNNB1 gene, encompassing the sequence for glycogen synthetase kinase-3beta phosphorylation, were performed in 11 tumors. Heterozygous substitution mutations at codon 37 in two cases (S37F and S37C) and at codon 41 in one case (T41A) were found in three endometrioid lesions (one borderline tumor and two carcinomas) with abnormal beta-catenin expression. Three endometrioid carcinomas and five tumors of other histological types analyzed showed normal DNA sequences. These results implicate beta-catenin gene mutations in ovarian malignant transformation with a characteristic phenotype: endometrioid ovarian carcinoma.

Tumour growth and cell kinetics in variants of a human endometrial adenocarcinoma expressing either wild-type or mutant p53

We have compared the baseline cell proliferation and tumour growth in two variants of a human endometrial adenocarcinoma grown in nude mice. One of these tumour variants expressed wild-type p53 whereas the other had mutations of the p53 gene at codon 175 in both alleles and at codon 248 in one allele. There was no difference in growth rate between the tumour variants. Cell proliferation parameters, such as labelling index and S-phase fraction, were significantly increased in the tumour with mutated p53 and consequently there was a significantly lower proportion of cells in the G1-phase, proposing an at least partial loss of suppressor function in this tumour. Semi-quantitative analysis of the p53 and bcl-2 proteins showed a significant overexpression of p53 and a decreased expression of the bcl-2 protein in the p53 mutated tumour variant compared with the variant with wild-type p53. We conclude that wild-type p53 protein acts as an active suppressor in the regulation of the baseline growth and cell kinetics of this tumour and could be linked through a p53--bcl-2 system in human endometrial adenocarcinomas.

[Detection and sequence analysis of the p53 gene mutation in epithelial ovarian cancer]

OBJECTIVE

To find the characteristics of p53 gene mutation in epithelial ovarian cancer and to analyze the relationship between p53 mutation and FIGO stage.

METHODS

p53 mutations in exon 5 to 7 were detected by single-strand conformational polymorphism (SSCP) and sequencing technique.

RESULTS

8 of 46 tumor tissues demonstrated a SSCP band shift in the region of the gene. All of them have been characterized to represent DNA alterations by sequencing, including 8 point mutations (6 missence, 1 silent mutation and 1 in intron) and a 1-base pair insertion (introducing a stop codon downstream). Overall, 88.9% of mutation were transitions, and most of them are G-->A transitions (7/8, 87.5%). 62.5% of the mutation were found in 175 and 245 codon. The percentage of the mutation in stage I and stage II was 20.0%, and in stage III and stage IV was 16.7% (P > 0.05).

CONCLUSION

The arising of p53 mutations in ovarian cancer is due to spontaneous error in DNA synthesis and repair. Codon 175, 245 are the two mutational hot spots. There is no relationship between the mutation of p53 gene and FIGO stage in epithelial ovarian cancer.

A dualistic model for endometrial carcinogenesis based on immunohistochemical and molecular genetic analyses

Clinicopathological, immunohistochemical and molecular genetic analyses of endometrial carcinoma suggest different pathogenetic pathways for endometrioid and serous carcinoma. Most endometrioid carcinomas are associated with endometrial hyperplasia, are ER/PR positive, p53 negative and express low Ki-67. In contrast, almost all serous carcinomas develop from endometrial intraepithelial carcinoma (EIC) in a background of atrophy. These tumors are ER/PR negative, strongly express p53 and show high Ki-67 labeling. On the molecular genetic level, 25-30% of endometrioid carcinomas show microsatellite instability (MI), 25-30% harbor mutant K-ras and less than 10% have mutant p53. In contrast, more than 90% of serous carcinomas have p53 mutations, 2% K-ras mutations and none MI. Among endometrioid carcinomas, K-ras mutations occur most frequently in FIGO grade 2 and 3 tumors and p53 mutations in FIGO grade 3 tumors. In contrast, MI is equally distributed among all FIGO grades. These findings support the view that endometrioid carcinoma develops slowly in a progressive fashion from endometrial hyperplasia. Mutation of p53 occurs late in tumor progression. Thus, endometrioid carcinogenesis resembles the proposed model for colorectal carcinogenesis. In contrast, serous carcinoma develops rapidly from EIC in a background of atrophy. Mutation of p53 occurs early in serous carcinogenesis and this may account for the highly aggressive behavior of this tumor.

p16/MTS1 inactivation in ovarian carcinomas: high frequency of reduced protein expression associated with hyper-methylation or mutation in endometrioid and mucinous tumors

Inactivation of the tumor-suppressor gene p16 (MTS1/ CDKN2/INK4a) has been described in various human malignancies. Although p16 deletion has been found in various ovarian tumor cell lines, p16 inactivation by homozygous deletion or mutation has been reported only sporadically in primary ovarian carcinomas. In a comprehensive study, we analyzed p16 protein expression by immuno-histochemistry (IHC) on paraffin sections of 94 primary ovarian carcinomas of different histological subtype. Loss of expression was detected in 19 primary tumors (20%), mainly mucinous and endometrioid carcinomas. To reveal the cause of suppressed expression, we performed (i) analysis of homozygous deletions by comparative PCR after micro-dissection, (ii) mutation analysis by single-strand conformation polymorphism analysis and subsequent direct sequencing and (iii) methylation-specific PCR to determine the methylation status of 5'-CpG islands. Loss of or weak p16 expression was caused by hyper-methylation (12/19 IHC-negative cases), somatic mutation (10 tumors) or homozygous deletion (1 case). Aberrant p 16 results by one of these methods were detected in 71-79% of endometrioid and mucinous, but in only 10% of serous-papillary, carcinomas. Our data suggest that p16 inactivation is a typical feature of certain subtypes of ovarian carcinoma.

Mutations in the BRCA1-associated RING domain (BARD1) gene in primary breast, ovarian and uterine cancers

Germline alterations of BRCA1 result in susceptibility to breast and ovarian cancer. The protein encoded by BRCA1 interacts in vivo with the BRCA1-associated RING domain (BARD1) protein. Accordingly, BARD1 is likely to be a critical factor in BRCA1-mediated tumor suppression and may also serve as a target for tumorigenic lesions in some human cancers. We have now determined the genomic structure of BARD1 and performed a mutational analysis of 58 ovarian tumors, 50 breast tumors and 60 uterine tumors. Seven polymorphisms were detected within the 2.34 kb coding sequence of BARD1 . Somatically acquired missense mutations were observed in one breast carcinoma and one endometrial tumor; in at least one of these cases, tumor formation was accompanied by loss of the wild-type BARD1 allele, following the paradigm for known tumor suppressor genes. In addition, a germline alteration of BARD1 was identified in a clear cell ovarian tumor (Gln564His); again, loss of the wild-type BARD1 allele was observed in the malignant cells of this patient. The Gln564His patient was also diagnosed with two other primary cancers: a synchronous lobular breast carcinoma and a stage IA clear cell endometrioid cancer confined to an endometrial polyp 6 years earlier. These findings suggest an occasional role for BARD1 mutations in the development of sporadic and hereditary tumors.

A novel 4 cM minimal deletion unit on chromosome 6q25.1-q25.2 associated with high grade invasive epithelial ovarian carcinomas

Detailed deletion mapping of chromosome 6q has shown that the highest percentage of loss of heterozygosity (LOH) is located at 6q25-q27 and suggested that an ovarian cancer associated tumor suppressor gene may reside in this region. To further define the smallest region of common loss, we used 12 tandem repeat markers spanning a region no more than 18 cM, located between 6q25.1 and 6q26, to examine allelic loss in 54 fresh and paraffin embedded invasive ovarian epithelial tumor tissues. Loss of heterozygosity was observed more frequently at the loci defined by marker D6S473 (14 of 32 informative cases, 44%) and marker D6S448 (17 of 40 informative cases, 43%). Detailed mapping of chromosome 6q25-q26 in these tumor samples identified a 4 cM minimal region of LOH between markers D6S473 and D6S448 (6q25.1-q25.2). Loss of heterozygosity at D6S473 correlated significantly both with serous versus non-serous ovarian tumors (P=0.040) and with high grade versus low grade specimens (P=0.023). The results suggest that a 4 cM deletion unit located at 6q25.1-q25.2 may contain the putative tumor suppressor gene which may play a role in the development and progression of human invasive epithelial ovarian carcinomas (IEOC).

Overexpression of p53, EGFR, c-erbB2 and c-erbB3 in endometrioid carcinoma of the ovary

OBJECTIVES

To determine overexpression of p53, EGFR, c-erbB-2 and c-erbB-3 in endometrioid carcinoma of the ovary and to evaluate the prognostic significance of these results, especially, coexisting overexpression of p53 and one of the member of type I growth factor receptor family.

METHODS

Overexpressions of the p53, EGFR, c-erbB-2 and c-erbB-3 protein were studied by immunohistochemistry in paraffin-embedded tumor tissue from 28 patients with endometrioid carcinoma of the ovary.

RESULTS

11 (39.3%), 13 (46.4%), and 14 (50.0%) were stained positively with p53, c-erbB-2 and c-erbB-3 monoclonal antibodies. 13 (46.4%) was stained positively with EGFR polyclonal antibody. There were no relationship between p53, EGFR, C-erbB-2, c-erbB-3 and histologic grade, lymph node metastasis. The percentage of tumors with over expression of p53, EGFR, C-erbB-2 and c-erbB-3 was higher in those with stage II-III tumors compared with those with stage I, in patients with residual tumor after initial surgery compared with those without. A high survival rate was observed in patients without p53, EGFR, c-erbB-2 and c-erbB-3 overexpression respectively than those with. A highest survival rate was observed in patients with both p53 and one of EGFR, c-erbB-2 and c-erbB-3 negative compared with those both positive or either of both positive.

CONCLUSION

Overexpression of p53, EGFR, c-erbB-2 and C-erbB-3 resulted in a poorer prognosis respectively. Overexpression of both p53 and one of the EGFR, c-erbB-2 and c-erbB-3 is a worse prognostic indicator in patients with endometrioid carcinoma of the ovary.

Alteration of p16 and p15 genes in common epithelial ovarian tumors

We have examined the roles of 2 putative tumor-suppressor genes, the p16 and p15 inhibitor-of-cyclin-dependent-kinase genes, in the most commonly occurring epithelial tumors of the human ovary. Expression of p16 mRNA, examined by RT-PCR, was significantly reduced in 15 of the 48 tumors. Aberrant expression of p16 protein, detected by immunohistochemistry, occurred in 22 of 60 tumors, more frequently in low-grade tumors, and had significant correlation with low p16 mRNA expression. Hypermethylation of a site within the 5'-CpG island of the p16 gene was significantly associated with loss of p16 mRNA and protein expression. Homozygous gene deletion, evaluated by differential PCR analysis, was found in 2 tumors for the p16 gene and in 1 tumor for the p15 gene among 70 ovarian tumors examined. PCR-SSCP analysis detected point mutations in p16 in 4 tumors and in p15 in 1 tumor. One was a 38-bp deletion, from codons 48 to 60, in a mucinous tumor of low malignant potential; another was a non-sense mutation in codon 60 in a mucinous adenocarcinoma. The remaining 2 mutations were mis-sense mutations, one in codon 58 and the other in codon 60, in 2 endometrioid adenocarcinomas. We conclude that inactivation of p16, by loss of p16 mRNA and protein expression as a consequence of hypermethylation of the 5'-CpG island, rather than by gene deletion or point mutation, may play an important role in the genesis of human ovarian epithelial tumors.

A case-matched molecular comparison of extraovarian versus primary ovarian adenocarcinoma

BACKGROUND

Extraovarian müllerian adenocarcinoma (EOM) resembles primary ovarian carcinoma (POC) both histologically and clinically, yet little is known regarding the molecular genetic characteristics of this entity. The objective of this study was to compare the expression of three molecular markers of tumor behavior in EOMs and POCs.

METHODS

Forty-four patients meeting strict criteria for EOM were identified and matched to POC controls for age, stage, tumor histology and grade, cytoreductive surgery, and survival. Immunohistochemistry was used to determine overexpression of p53 and HER-2/neu. DNA content was evaluated by flow cytometry. Direct DNA sequencing of exons 5-8 of the p53 gene was performed in nine EOM tumors. Statistical comparisons were made using chi-square, Kaplan-Meier, and Mantel-Cox log rank methods.

RESULTS

Overexpression of HER-2/neu was demonstrated in 59% (26 of 44) of the EOM group versus 36% overexpression (16 of 44) in the POC controls (P = 0.05). Overexpression of p53 was noted in 48% of the EOM cases, similar to the 59% incidence observed in the control group (P = 0.29). Missense mutations were found in 9 of 9 EOM tumors showing strong p53 nuclear immunostaining. No significant difference in the incidence of aneuploidy was observed when EOM cases were compared with POC controls (65% vs. 63%). High tumor grade was strongly associated with HER-2/neu overexpression in the EOM group (P = 0.002). None of the parameters studied were predictive of prognosis within the EOM and POC groups.

CONCLUSIONS

Although overexpression of p53 protein, p53 gene mutations, and abnormal DNA content were similar between EOMs and POCs, EOMs demonstrated almost twice the rate of HER-2/neu overexpression. This result suggests that distinct genetic events may be responsible for malignant transformation in EOMs versus POCs.

Molecular analysis of synchronous uterine and ovarian endometrioid tumors

The presence of simultaneous carcinomas involving both the ovary and uterine corpus presents a diagnostic challenge, particularly if the tumors have a similar histology. The classification of these lesions as either two separate primary tumors, or as a single primary tumor with a metastasis has significant implications with respect to patient prognosis and recommendations for therapy. Although several morphologic criteria have been proposed as guidelines for the classification of these lesions, certain cases remain difficult to confidently classify. The application of current molecular biology techniques to pathological specimens can provide genetic information than can be helpful in establishing the relationship between synchronous neoplasms. Specifically, the use of tissue microdissection and polymerase chain reaction (PCR) amplification of DNA can be helpful. In this study we used polymorphic DNA markers on chromosomes 17q21.3-22 and 11q13 to study loss of heterozygosity (LOH) in 13 patients who presented with endometrioid tumors in both the uterus and ovary. Ten of the 13 cases showed LOH in one or both tumors. In eight of the 13 cases the detected LOH either chromosome 17q21.3-22 or 11q13 occurred selectively in only one of the two tumor sites. The results of this study suggest that the eight cases with LOH selective for one tumor site represent patients with two separate primary tumors. Molecular analysis may be useful in determining the relationship of synchronous uterine and ovarian endometrioid neoplasms.

Expression of antimetastatic gene nm23-H1 in epithelial ovarian cancer

OBJECTIVE

To investigate the expression of nm23-H1 in epithelial ovarian cancer.

METHODS

A total of 55 specimens from patients with epithelial ovarian cancers, 15 patients with serous cancers, 7 with mucinous cancers, 17 with endometrioid cancers and 16 with adenocarcinomas, were examined for the expression of nm23-H1 by means of the immunohistochemical technique.

RESULTS

The total positive rate was 23.64% (13/55). The tissular nm23-H1 immunostaining had significantly higher expression in mucinous cancer (57.14%) than in other histologic types of epithelial ovarian cancer (P < 0.05). Compared to that in the primary tumor, nm23-H1 expression in the omental metastatic tumor in the same patient was reduced.

CONCLUSIONS

The expression rate of nm23-H1 is higher in the primary tumors than in the metastatic tumors and is different in various histologic subtypes of epithelial ovarian cancer. The expression of nm23-H1 may participate in the inhibitory process of tumor invasion.

Evidence for divergence of DNA copy number changes in serous, mucinous and endometrioid ovarian carcinomas

Comparative genomic hybridization was applied to detect and map changes in DNA copy number in 24 well or moderately differentiated epithelial ovarian carcinomas (eight serous, eight mucinous and eight endometrioid carcinomas). Twenty-three of the 24 tumours showed changes in DNA copy number in one or several regions (median 4, range 1-17). Gains were more frequent than losses (ratio 1.6:1.0). The most frequent gains occurred in chromosomes 1q (38%), 2p (29%), 7q (25%), 8q(38%) and 17q (38%), and the most common losses were located in chromosomes 8p (21%), 9p (25%) and 13q (21%). High-level amplifications were detected in seven tumours at 1q22-32, 2p15-22, 3qcen-23, 6p21-22 and 8q. In the three histological subtypes the copy number karyotypes showed substantial differences. Gains at 1q were observed in endometrioid (five cases) and serous tumours (four cases). Increased copy number at 10q was seen in endometrioid tumours only (four cases), whereas gains at 11q occurred mostly in serous tumours (four cases). In mucinous tumours, the most common copy number change was a gain at 17q (six cases). The results show that, in epithelial ovarian carcinoma, changes in DNA copy number are a rule rather than an exception, chromosomes 1, 2, 7, 8, 9, 13 and 17 being the most frequently affected. The diverging pattern of genetic changes seen in epithelial ovarian carcinomas with different histological phenotypes suggests that various pathways may lead to tumorigenesis and/or progression in these subgroups.

Involvement of chromosome 6 in endometrial cancer

Cytogenetic investigation was performed on direct preparations of 15 endometrial cancers showing different histotypes. Clonal abnormalities were found in 11 out of 13 analysable cases. The modal chromosome number was near diploid in all cases. The abnormal karyotypes contained relatively simple numerical or structural aberrations in the majority of tumours. In contrast, two neoplasms with serous papillary and mixed mullerian morphological features shared multiple complex changes as well as cytogenetic evidence of intratumoral heterogeneity. The most frequent chromosome abnormality in our series of endometrial neoplasms was 6q deletion, which was detected in serous papillary, endometrioid and mixed mullerian tumours. The loss of the 6q region, which is also frequently involved in ovarian carcinoma, suggests a relationship between endometrial and ovarian cancers based on a common histogenesis.

Absence of deletions but frequent loss of expression of p16INK4 in human ovarian tumours

The cyclin-dependent kinase inhibitor p16 gene (P16, MTS1, CDKN2) has been shown to be altered by deletion or point mutation in some human tumours and cancer cell lines, suggesting that it works as a tumour suppressor. We analysed p16 gene mutation and p16 protein expression in 42 primary ovarian carcinomas and in five human ovarian cancer cell lines. Polymerase chain reaction (PCR) amplifications of exons 1 and 2 of the gene showed no deletion or gross rearrangement in the p16 gene. The lack of deletion was further demonstrated by Southern blot analysis. Looking for point mutations, we used single-strand confirmation polymorphism (SSCP) analysis and, in half of the tumours, we sequenced both strands of exons 1 and 2. No mutations were detected. In 11 out of 42 patients (26%), however, we detected no protein expression by Western blot analysis, suggesting that decreased expression of p16 rather than deletion of the gene can occur in a significant percentage of human ovarian cancers. In the same experiment CDK4 protein was found homogeneously expressed in all the tumour specimens and in the five cell lines. The lack of expression of p16 was not due to hypermethylation of the gene assessed by digestion of genomic DNAs with a methylation sensitive enzyme, suggesting that other mechanisms, not yet identified, are involved in the decreased expression of the p16 gene in human ovarian tumours.

K-ras point mutations in endometrial carcinoma: effect on outcome is dependent on age of patient

Mutations involving the K-ras proto-oncogene are believed to play an important role in the mechanism of tumorigenesis for many human cancers and occur in 10-30% of endometrial carcinomas. In the present study 221 cases of endometrioid endometrial carcinoma obtained from Japanese patients with average follow-up of 41 months were examined for point mutations in codon 12 of K-ras through use of the polymerase chain reaction. In 103 cases lymph node dissection had been performed. K-ras mutations were significantly associated with the presence of lymph node metastases (P < 0.04). Since endometrial carcinoma in premenopausal women generally behaves less aggressively than tumors of similar histologic grade arising in postmenopausal patients, we evaluated the effect of K-ras mutation on outcome in patients stratified into three different age categories (<53 years, premenopausal; 54-59 years, perimenopausal; >60 years, postmenopausal). In the postmenopausal age group (>60 years), the presence of K-ras mutations was statistically significantly associated with patients who died or experienced recurrence (41.2% vs 13.0%; P < 0.03). This was related to a dramatic (greater than eightfold; P = 0.011) increase in the likelihood of adverse outcome between the premenopausal and postmenopausal states for patients whose tumors contained mutant K-ras. These findings point to a possible role for K-ras activation in the mechanism(s) responsible for more aggressive clinical behavior of endometrioid endometrial cancer that is observed in postmenopausal patients.

Aromatase cytochrome P450 gene expression in endometrial carcinoma

We analysed aromatase gene expression and its regulation in seven cases of endometrioid endometrial carcinoma. Immunohistochemistry revealed the presence of strong aromatase immunoreactivity in the stromal cells of carcinoma in five out of seven cases. A polymerase chain reaction after reverse transcription (RT PCR) revealed varying levels of aromatase transcripts (0.1-27.0 amol ng(-1) total mRNA) in five cases. The alternative use of multiple exons 1 was also examined by identifying various human aromatase transcripts specific for exons 1 in RT-PCR products. Gonadal type or exon 1d was primarily used in three cases in which aromatase overexpression was not detected. The two cases in which fibroblasts type or exon 1b was used with other exons 1 as minor transcripts demonstrated aromatase overexpression in immunohistochemistry and RT PCR analysis. Further studies are required, but alternative splicing as well as use of multiple exons 1 transcripts may result in increased aromatase expression in stromal cells observed in endometrial carcinoma.

[Study of the amplification and expression of c-erbB2 oncogene in epithelial ovarian tumors]

Protooncogene c-erbB2 amplification and expression were studied in 62 cases of epithelial ovarian tumor by using immunohistochemical method and in situ hybridization. c-erbB2 gene amplification was observed in 30 of 47 ovarian cancers (63.8%) and in none of 15 benign tumors. The gene expression was found in 38 of the former and in 9 of the latter tumors. The gene amplification showed significant difference between malignant and benign tumors (P < 0.01). But for gene expression, only the strongly positive staining demonstrated significant difference (P < 0.01). There was correlation between c-erbB2 gene amplification and expression in epithelial ovarian carcionoma. The status of c-erbB2 gene amplification and expression had no relationship with histopathological types of ovarian carcinoma. The results indicate that there is extensive expression of c-erbB2 in epithelial ovarian tumors and it is over-expressed in ovarian carcinoma. Gene amplification is perhaps only one way by which c-erb2 gene is activated, and its overexpression might be one of the factors that promotes epithelial ovarian cancer development.

nm23 expression in tissue sections and tumor effusion cells of ovarian neoplasms

The genetic changes involved in the metastatic process of ovarian epithelial cancer remain undetermined. The expression of nm23, a putative metastasis-suppressor gene product, was assessed immunohistochemically in malignant and benign ovarian neoplasms, considering histology of tumors and clinical advancement of disease. Comparison of nm23 protein content in tissue sections and respective cyst and/or ascitic fluid cells was also performed. Significant heterogeneity of nm23 immunostaining was observed, and no correlation with histological subtype of ovarian carcinoma was found. Expression of nm23 was higher in carcinomas compared with benign tumors. A significant trend to have a higher nm23 reactivity in ascitic fluid cells vs. primary tumors was observed. Our results indicate that the increase of nm23 reactivity is activated in the early stages of the disease and that the progression of ovarian carcinoma is accompanied by overexpression of nm23 protein. Our observations did not confirm the postulated role of nm23 as a suppressor gene in ovarian cancer.

Frequent deletion of chromosome 1p sequences in an aggressive histologic subtype of endometrial cancer

The molecular genetic events underlying endometrial tumorigenesis are ill-defined at present. We have identified a region on the short arm of chromosome 1 which is frequently deleted in endometrial cancers. The region of deletion has been localized to bands 1p32-33. Deletion of 1p32-33 is seen more frequently in cancers of the highly aggressive papillary serous type than in cancers of the less-aggressive endometrioid type. These data suggest the presence of a tumor suppressor gene on 1p32-33 which is specifically involved in the development of endometrial cancers with poor outcome.