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Using RNA fingerprinting (RAP) strategy and Northern blot analysis, we identified a differentially expressed sequence DOC-2 which is detectable in all normal human ovarian surface epithelial (HOSE) cell cultures but not in ovarian cancer cell lines and tissues. Subsequent cloning of DOC-2 from a cDNA library generated from the HOSE cells was carried out using the 3′ and 5′ RACE approach. A 3268 base pair full length cDNA of DOC-2 was isolated and sequenced. The predicted protein has a length of 770 amino acids. Homology search of all NCBI sequences indicated that the amino acid sequence of DOC-2 shares 93% homology with the mouse p96/mDab2 phosphoprotein and has a phosphotyrosine interacting domain (PID) and multiple SH3 binding motifs. Chromosomal localization by FISH showed that the DOC-2 gene is located on 5p13. Western blot analysis showed that the 105 kDa DOC-2 protein was down-regulated in all the carcinoma cell lines. In-situ immunohistochemistry performed on normal ovaries, and benign, borderline and invasive ovarian tumor tissues showed down regulation of DOC-2 protein particularly in serous ovarian tumor tissues. When DOC-2 was transfected into the ovarian carcinoma cell line SKOV3, the stable transfectants showed significantly reduced growth rate and ability to form tumors in nude mice. These data suggest that down-regulation of DOC-2 may play an important role in ovarian carcinogenesis. [ABSTRACT FROM AUTHOR]

We have used polymerase chain reaction (PCR) amplification of tandem repeats to study the pattern of allelic loss on chromosome X11.2-q12 in borderline and invasive epithelial ovarian tumors. Using eight microsatellite markers spanning Xq11.2-q12, 41 borderline and 65 invasive ovarian tumors, together with their corresponding normal tissues, were analysed. The highest percentage of loss of heterozygosity (LOH) was observed at the DXS1194 locus in borderline tumors (four of 16 informative cases, 25%) and at the androgen receptor (AR) locus in invasive epithelial ovarian tumors (18 of 47 informative cases, 38%). X chromosome activation studies performed in cases with LOH at the AR locus showed that the allelic loss at the AR locus is not confined to the inactive allele. A one centimorgan region including the AR locus and flanked by the primers DXS1161 and PGK1P1 was identified as the smallest common loss region in both borderline and invasive epithelial ovarian tumors. [ABSTRACT FROM AUTHOR]

Background: Papillary serous carcinoma of the peritoneum (PSCP) diffusely involves peritoneal surfaces, while it spares or only superficially involves the ovaries. PSCP is histologically indistinguishable from serous epithelial ovarian carcinoma, and it may develop years after oophorectomy. The molecular pathogenesis of PSCP remains unresolved, although preliminary data suggest a multifocal origin in some cases. Patients with germline BRCA1 mutations may develop PSCP in addition to breast and ovarian carcinomas. The purpose of this study was to utilize the androgen receptor (AR) gene locus to test the hypothesis that some cases of PSCP have a multifocal origin and to determine if patients with germline BRCA1 mutations develop multifocal PSCP.Methods: Specimens of normal and tumor tissues from 22 women with PSCP were obtained, and DNA was extracted. The AR gene locus was evaluated for patterns of loss of heterozygosity (LOH) and X-chromosome inactivation. The methylation-sensitive Hpa II restriction enzyme was used to differentiate the active and inactive X chromosomes. Germline BRCA1 mutation status of the patients was determined previously.Results: Genetic analysis of tumor specimens indicated that five (23%) of 22 case subjects had patterns of selective LOH at the AR locus, consistent with multifocal, polyclonal disease origin. Two patients with selective LOH also had alternating X-chromosome inactivation patterns. Patients with germline BRCA1 mutations were more likely to have evidence of multifocal disease (two-sided Fisher's exact test, P = .01).Conclusions: Our results show that PSCP has a multifocal origin in at least some cases. Furthermore, patients with germline BRCA1 mutations are more likely to develop multifocal PSCP than are patients without BRCA1 mutations. [ABSTRACT FROM AUTHOR]

Immune cells in the ovarian stromal microenvironment play an important role in ovarian tumorigenesis. Up-regulation of immune cell-derived mediators during ovulation may generate a proinflammatory niche, which may subsequently induce transformation of normal ovarian epithelial cells or endometriotic cells in the ovary. Once transformed ovarian epithelial cells develop, an immunoediting process occurs in which immune cells and their mediators dictate the development and progression of ovarian tumors. Tumor cells also develop several mechanisms to evade anti-tumor immunity by developing an immunosuppressive microenvironment. The differences in the population of immune cells infiltrating into ovarian tumor tissues are associated with differences in clinical outcomes. The underlying molecular mechanisms of the association begin to unravel with the development of microdissection techniques, high throughput technologies, in vitro functional assays, and in vivo mouse modeling. A better understanding of the complex relationship between ovarian tumor cells and the associated immune cells will allow us to develop novel immunologic strategies for ovarian cancer prevention and treatment.

Analysis of multiple proteins is thought to be essential for establishment of signature proteomic patterns that may distinguish cancer from non-cancer. Surface-enhanced laser desorption/ionization (SELDI) is an affinity-based mass spectrometric method in which proteins of interest are selectively absorbed to a chemically modified surface on a biochip. This technology may provide protein profiling of a variety of biological specimens. In this study, we explored whether the protein biochip SELDI approach could differentiate cervical cancer from non-cancer cohorts. We screened protein profiles generated by SELDI in 62 cervical epithelial cell samples microdissected from 35 invasive cervical cancer and 27 age-matched normal cervix tissue specimens, respectively. The cell lysates of pure populations of cervical cells were applied onto Ciphergen ProteinChip WCX2 Arrays. Proteins bound to the chips were analyzed on a ProteinChip Reader Model PBS II. Derived proteomic patterns were converted to a simple proteomic scoring for distinguishing cancer from non-cancer cohorts. SELDI protein profiles of cell lysates from 20 cervical cancer and 15 normal cervix tissue specimens were used to train and develop a classification scoring system that used a seven-protein mass pattern. The training samples could be correctly discriminated. When a test set of 27 samples was used for evaluation of this scoring system to distinguish cervical cancer from non-cancer, a sensitivity of 87%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 86% for the test population were obtained. All seven proteins appeared to be down regulated in cervical cancer. The results from this study indicate that the proteomics approach of SELDI mass spectrometry, in combination with a simple scoring system, may distinguish cervical cancer from its normal counterpart. If this approach is also workable in the analysis of cervical exfoliated cell lysate, it might potentially be used in the early diagnosis of invasive cervical cancer. In addition, the identification of these specific proteins in cervical cancer may also facilitate the discovery of new cervical tumor marker(s).

DOC-2/hDab-2 was identified due to the loss of its expression in primary ovarian cancer cells. It is believed that loss of DOC-2/hDab-2 expression is one of the early events of ovarian malignancy. These results suggest a function of DOC-2/hDab-2 as a tumor suppressor. However, it is not clear how DOC-2/hDab-2 negatively regulates cancer cell growth. In this report, we demonstrate that DOC-2/hDab-2 expression in breast cancer cells resulted in sensitivity to suspension-induced cell death (anoikis). This event was associated with the down-regulation of the integrin-linked kinase (ILK) activity. Since ILK is a key factor in regulating the cellular signaling in responding to the extracellular signals through adhesion molecules like integrins, our results indicate that DOC-2/hDab-2 may prevent tumor growth and invasion by modulating the anti-apoptotic ILK pathway.

Background: Screening biomarkers for ovarian cancer are needed because of its late stage at diagnosis and poor survival. We used microarray technology to identify overexpressed genes for secretory proteins as potential serum biomarkers and selected prostasin, a serine protease normally secreted by the prostate gland, for further study., Methods: RNA was isolated and pooled from three ovarian cancer cell lines and from three normal human ovarian surface epithelial (HOSE) cell lines. Complementary DNA generated from these pools was hybridized to a microarray slide, and genes overexpressed in the cancer cells were identified. Real-time quantitative polymerase chain reaction was used to examine prostasin gene expression in ovarian cancer and HOSE cell lines. Anti-prostasin antibodies were used to examine prostasin expression and to measure serum prostasin by an enzyme-linked immunosorbent assay in 64 case patients with ovarian cancer and in 137 control subjects. Previously determined levels of CA 125, an ovarian cancer marker, were available from about 70% of all subjects. All statistical tests were two-sided., Results: Prostasin was detected by immunostaining more strongly in cancerous ovarian epithelial cells and stroma than in normal ovarian tissue. The mean level of serum prostasin was 13.7 microg/mL (95% confidence interval [CI] = 10.5 to 16.9 microg/mL) in 64 case patients with ovarian cancer and 7.5 microg/mL (95% CI = 6.6 to 8.3 microg/mL) in 137 control subjects (P<.001, after adjustment for the subject's age, year of collection, and specimen quality). In 14 of 16 case patients with both preoperative and postoperative serum samples, postoperative prostasin levels were statistically significantly lower than preoperative levels (P =.004). In 37 case patients with nonmucinous ovarian cancer and in 100 control subjects for whom levels of CA 125 and prostasin were available, the combination of markers gave a sensitivity of 92% (95% CI = 78.1% to 98.3%) and a specificity of 94% (95% CI = 87.4% to 97.7%) for detecting ovarian cancer., Conclusions: Prostasin is overexpressed in epithelial ovarian cancer and should be investigated further as a screening or tumor marker, alone and in combination with CA 125.

The role of serous borderline ovarian tumors (BOTs) in the pathogenesis of serous ovarian carcinomas is unclear. Some authors have compared mutations in serous BOTs to those in serous ovarian carcinomas, but the data on two common oncogenes, p53 and K-ras, remain inconclusive. To further clarify the relationship between the two tumors, we performed mutational analysis on tumors from a set of eight patients who first presented with advanced-stage serous BOTs and later developed grade 1 serous carcinomas. Epithelium from eight advanced-stage serous BOTs and subsequent grade 1 papillary serous carcinomas was microdissected and retrieved using a PixCell laser-capture microscope. Stroma was dissected as an internal control. The DNA was extracted with proteinase K and analyzed by single-strand conformational polymorphism-PCR for p53 and K-ras mutations. Bands with altered motility were analyzed by direct cycle sequencing. Seven of eight patients demonstrated different mutations in the secondary tumor compared with the primary tumor. For three patients, p53 mutations were identified in the BOTs that were absent from the carcinomas, suggesting a nonclonal origin for the carcinomas. These findings are consistent with the hypothesis that advanced-stage serous BOTs represent a distinct pathological entity compared with grade 1 serous epithelial ovarian carcinoma.

Epidemiological data have implicated reproductive hormones as probable risk factors for ovarian cancer (OCa) development. Although pituitary and sex hormones have been reported to regulate OCa cell growth, no information is available regarding whether and how they influence normal ovarian surface epithelial (OSE) cell proliferation. To fill this data gap, this study has compared cell growth responses to gonadotropins and sex steroids in primary cultures of human OSE (HOSE) cells with those observed in immortalized, nontumorigenic HOSE cells and in OCa cell lines. Both malignant and normal cell lines/cultures responded equally well to the stimulatory actions of luteinizing hormone and follicle-stimulating hormone and to 17beta-estradiol and estrone, although the latter estrogen has a much lower affinity for estrogen receptor than does the former estrogen. In normal HOSE cell cultures/lines, 5alpha-dihydrotestosterone was found to be more effective than testosterone in stimulating cell growth, but in OCa cell lines, 5alpha-dihydrotestosterone and testosterone are equally potent. One OCa cell line, OVCA 433, was found to be nonresponsive to androgen stimulation. In general, primary cultures of normal HOSE cells exhibited the greatest hormone-stimulated growth responses (>10-fold enhancement), followed by immortalized HOSE cell lines (4-5-fold enhancement) and by OCa cell lines (2-4-fold enhancement). Interestingly, progesterone (P4), at low concentrations (10(-11) to 10(-10) M), was stimulatory to HOSE and OCa cell growth, but at high doses (10(-8) to 10(-6) M), P4 exerted marked inhibitory effects. In all cases, cotreatment of a cell culture/line with a hormone and its specific antagonist blocked the effect of the hormone, confirming specificity of the hormonal action. Taken together, these data support the hypothesis that reproductive states associated with rising levels of gonadotropins, estrogen, and/or androgen promote cell proliferation in the normal OSE, which favors neoplastic transformation. Conversely, those states attended by high levels of circulating P4, such as that seen during pregnancy, induce OSE cell loss and offer protection against ovarian carcinogenesis.

Secreted protein acidic and rich in cysteine (SPARC) is an extracellular Ca(2+)-binding matricellular glycoprotein that associates with cell populations undergoing migration, morphogenesis, and differentiation. Studies on endothelial cells have established that its principal functions in vitro are counteradhesion and antiproliferation. The mechanism(s) underlying these antitumor effects is unknown. In this study, we showed that SPARC expression in ovarian cancer cells is inversely correlated with the degree of malignancy. The immunohistochemical data presented here confirmed the importance of diminished SPARC expression in ovarian cancer development. Treating human ovarian surface epithelial cells and ovarian cancer cells with SPARC revealed that as SPARC inhibits the proliferation of both normal and cancer cells, it induces apoptosis only in cancer cells. This observation indicates that down-regulation of SPARC is essential for ovarian carcinogenesis as cancer cells become sensitized to the apoptotic activity of SPARC during malignant transformation. We also showed here the first direct evidence that putative SPARC receptors are present on ovarian epithelial cells. Their levels are higher in human ovarian surface epithelial cells than cancer cells. Binding of SPARC to its receptor is likely to trigger tissue-specific signaling pathways that mediate its tumor suppressing functions. Decrease in ligand-receptor interaction by the down-regulation of SPARC and/or its receptor is essential for ovarian carcinogenesis.

We explored the possible pathogenetic pathway for mucinous ovarian tumorigenesis by examining the k-ras mutational patterns in ovarian mucinous tumors (OMTs) with benign, borderline, and invasive epithelium in which the different types of mucinous epithelium are in close proximity. Sixteen patients with ovarian mucinous borderline tumors (OMBTs) and 4 patients with grade 1 ovarian mucinous adenocarcinomas (OMCs) were selected for the presence of a single histologic section which contained a clear "transition" zone from benign mucinous epithelium to borderline mucinous epithelium, and in four cases, to invasive epithelium. A PixCell II Laser Capture Microscope was used to microdissect and retrieve benign, borderline, and invasive epithelium separately from the 20 OMTs. Normal ovarian stroma from the same histologic section in each case was also microdissected and retrieved for use as a control. k-ras mutations were detected in these samples by PCR-SSCP analysis followed by direct PCR cycle sequencing. k-ras mutations were found in 8/16 (50%) of the OMBTs and 2/4 (50%) of the grade 1 OMCs. In 6 of these 10 cases (4 in OMBTs, 2 in grade 1 OMCs), the same k-ras mutation was found in both the benign and borderline (and invasive) regions. In 3 cases in which k-ras mutations were identified, the mutation was found in either the benign or borderline tissue samples alone, and in one case, two distinct mutations were found. No k-ras mutations were identified in the normal ovarian stroma. The presence of a k-ras mutation in adjacent benign and borderline regions of a single OMT may suggest a progression in the development of OMTs from benign to borderline and grade 1 OMCs. k-ras mutations, when they occur, are likely early genetic changes but may not alone be sufficient for malignant transformation of ovarian epithelium.

Summary: DOC-2/hDab2 (DOC-2) has tumor suppressive functions in ovarian cancer and choriocarcinoma. In these tumors, it negatively influences mitogenic signal transduction of growth factors and blocks ras activity. Pancreatic cancer exhibits a high frequency of K-ras gene mutations; however, it is not known whether DOC-2 expression is altered in these tumors. Therefore, we investigated DOC-2 expression in 22 pancreatic adenocarcinomas and in 6 pancreatic cancer cell lines. Findings in human tumors were compared with normal controls and correlated with clinicopathological data. Additionally, the influence of K-ras on DOC-2 transcription was investigated. Northern blot and Western blot analyses both demonstrated an increase of DOC-2 mRNA and protein levels in primary pancreatic cancers in comparison with normal controls. In situ hybridization showed DOC-2 mRNA expression in the majority of cancer cells of primary tumors, as well as in chronic pancreatitis-like lesions surrounding the cancer mass. Immunohistochemistry mirrored the in situ hybridization findings. In contrast, levels of expression of DOC-2 in lymph node metastases were markedly decreased in comparison with levels in primary tumors. In addition, in 5 metastatic pancreatic cancer cell lines, DOC-2 mRNA and protein levels were low, whereas quantitative RT-PCR demonstrated relatively higher levels in a nonmetastatic pancreatic cancer cell line. In conclusion, DOC-2 is overexpressed in primary pancreatic adenocarcinoma but down-regulated in metastatic disease, suggesting a tumor suppressor function of DOC-2 in the late steps of pancreatic carcinogenesis.

Investigation of genetic changes in tumors by loss of heterozygosity is a powerful technique for identifying chromosomal regions that may contain tumor suppressor genes. In this study, we determined allelic loss on chromosomes 5 and 6 in 29 primary early-stage epithelial ovarian carcinomas including 3 microscopically identified adenocarcinomas using a high-throughput PCR-based method combined with laser capture microdissection and whole genome amplification techniques. Twenty microsatellite markers spanning chromosomes 5 and 6 at an average distance of 20 cM were examined. High frequencies of loss on chromosome 5 were identified at loci D5S428 (48%), D5S424 (32%), and D5S630 (32%). Our study also showed that chromosome 6 exhibited high frequencies of loss of heterozygosity at loci D6S1574 (46%), D6S287 (42%), D6S441 (45%), D6S264 (60%), and D6S281 (35%). These results suggest that multiple tumor suppressor genes are located on five distinct regions on chromosomes 5 and 6, i.e., 5p15.2, 5q13-21, 6p24-25, 6q21-23, and 6q25.1-27, and may be involved in the early development of ovarian carcinomas.

Objectives: We have previously described that bioactive lysophospholipids-lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P), and sphingosylphosphorylcholine (SPC)-are present in ascitic fluids from patients with ovarian cancer. To understand the role of these lipids in ovarian cancer, we investigated the effects of these lipids on interleukin-8 (IL-8) production in ovarian cancer cells. IL-8 is a proinflammatory and proangiogenic factor, which is potentially involved in ovarian cancer development., Methods: The Clontech PCR-Select cDNA subtraction method (Clontech Laboratories, Inc., Palo Alto, CA) was used to identify genes potentially regulated by LPA in HEY and OCC1 ovarian cancer cell lines. Northern blot analysis was used to confirm and examine IL-8 mRNA regulation by lysolipids. Enzyme-linked immunosorbent assay (ELISA) was used for detecting secreted IL-8., Results: We describe here that LPA, S1P, and SPC increased mRNA levels (2- to 7-fold) and protein secretion (2- to 12-fold) of IL-8 from ovarian cancer cells (HEY, OCC1, and SKOV3) in vitro. These regulations were both dose- and time-dependent. All three lipids increased the stability IL-8 mRNA in HEY cells. In contrast to malignant ovarian cancer cells, immortalized human ovarian epithelial cells did not respond to any of these lipids to increase the secretion of IL-8, although these cells secreted similar basal levels of IL-8 (310 pg/ml/10,000 cells). Two breast cancer cell lines (MCF7 and T47D) secreted lower basal levels of IL-8 (48-80 pg/ml/10,000 cells), compared with ovarian cancer cells (200-500 pg/ml/10,000 cells). MCF7 cells responded to LPA, but not S1P and SPC, by increasing the secretion of IL-8. T47D and MCF10A, an immortalized breast cell line, did not respond to LPA, S1P, or SPC to increase IL-8 secretion., Conclusions: LPA, S1P, and SPC regulate the mRNA and protein levels of the proinflammatory and proangiogenic factor IL-8 in ovarian cancer cells. The pathological significance of these regulations in ovarian cancer remains to be further investigated., (Copyright 2001 Academic Press.)

Using the MICROMAX cDNA microarray system, we were able to identify genes that are differentially overexpressed in ovarian cancer. A total of 30 putative genes, which are differentially overexpressed in ovarian cancer cell lines, were identified. The differential expression of some of these genes was further confirmed by real-time RT-PCR. Using this strategy, we have identified genes that either overexpress in all cancer cell lines or in only some cancer cell lines. Further characterization of these genes will allow them to be exploited in diagnosis, prognosis, anticancer therapy, and molecular classification of ovarian cancer.

Ovarian cancer originates mainly from surface epithelial cells, which are potential targets of estrogen action. Using immunohistochemistry and RT-PCR analysis, aromatase (estrogen synthetase) can be detected in human ovarian surface epithelial tumors. In this study, we functionally characterized the aromatase expressed in a primary cell culture, normal human ovarian surface epithelial (HOSE) 17. The apparent K(m) and V(max) values were determined to be 5.8 +/- 0.5 nM, and 0.3 +/- 0.0 pmol/mg.h, respectively. The aromatase activity in HOSE 17 cells can be induced effectively by phorbol esters and forskolin, suggesting that estrogen biosynthesis in HOSE 17 cells is mainly regulated through protein kinase C- and protein kinase A-mediated mechanisms. Exon I-specific RT-PCR revealed that phorbol esters predominantly up-regulated promoter II. Whereas forskolin treatment increased exon I.3A-containing messenger RNA, the aromatase activity remained low in the cells treated with this agent. In vitro transcription/translation analysis using plasmids containing T7 promoter and the human snail gene (SnaH) as a reporter capped with different untranslated exon Is revealed that exon PII-containing transcripts were translated more effectively than exon I. 3-containing transcripts. These findings explain why aromatase activity is higher in cells with the PII-containing transcripts than is cells with the I.3-containing transcripts. Our results indicate that aromatase is functionally expressed in human ovarian surface epithelial cells and its expression is regulated at both the transcriptional and translational levels.

Germline mutations of BRCA1 and BRCA2 predispose to hereditary breast, ovarian, and possibly prostate cancer, yet structural mutations in these genes are infrequent in sporadic cancer cases. To better define the involvement of these genes in sporadic cancers, we characterized expression levels of BRCA1 and BRCA2 transcripts in cancer cell lines derived from neoplasms of the ovary, prostate, and breast and compared them with those expressed in primary cultures of normal epithelial cells established from these organs. We observed upregulation of BRCA1 and/or BRCA2 expression in six of seven ovarian cancer cell lines (OVCA420, OVCA429, OVCA432, ALST, DOV13, and SKOV3) when compared with levels found in normal ovary surface epithelial cells. Furthermore, five cancerous or immortalized prostatic epithelial cell lines (BPH-1, TSU-Pr1, LNCaP, PC-3, and DU145) also expressed higher levels of BRCA1 and/or BRCA2 mRNA than did primary cultures of normal prostatic epithelial cells. In contrast, only the estrogen receptor-positive MCF-7 cell line overexpressed these messages, whereas the estrogen receptor-negative breast cancer cell lines Hs578T, MDA-MB-231, and MDA-MB-468 showed no change in expression levels when compared with normal breast epithelial cells. In addition, expanding on our recent identification of a novel BRCA2 transcript variant carrying an in-frame exon 12 deletion (BRCA2 delta 12), we report increased expression of this variant in several ovarian, prostate, and mammary cancer cell lines (OVCA420, OVCA433, ALST, DOV13, SKOV3, TSU-Pr1, DU145, and MDA-MB-468). Most notably, high levels of BRCA2 delta 12 mRNA were detected in an estrogen receptor-positive breast cancer cell line, MCF-7, and in an androgen-independent prostate cancer cell line, DU-145. Interestingly, the wild-type BRCA2 transcript was barely detectable in DU145, which could be used as a model system for future investigations on BRCA2 delta 12 function. Taken together, our data suggest disruption of BRCA1 and/or BRCA2 gene expression in certain epithelial cancer cell lines of the ovary, prostate, and breast. Because wild-type BRCA1 and BRCA2 gene products increase during cell-cycle progression and are believed to exert growth-inhibitory action, enhanced expression of these genes in cancer cells may represent a negative feedback mechanism for curbing proliferation in fast-growing cells. At present, the functionality of BRCA2 delta 12 remains elusive., (Copyright 2000 Wiley-Liss, Inc.)

Objective: The goal of this work was to study the expression of epidermal growth factor receptor (EGFR) and c-erbB-3 and c-erbB-4 oncogenes in gestational trophoblastic diseases and normal first-trimester placenta., Study Design: Paraffin sections of 16 cases of partial mole, 25 cases of complete mole, 10 cases of gestational choriocarcinoma, and 11 cases of therapeutic abortion were studied immunohistochemically for EGFR, c-erbB-3, and c-erbB-4 proteins. The presence of EGFR mRNA was studied using in situ hybridization., Results: Staining for EGFR was detected immunohistochemically in all cell types in gestational trophoblastic diseases and normal placenta. In situ hybridization for EGFR mRNA correlated with immunostaining for EGFR in all tissues studied. All 10 cases of choriocarcinoma exhibited strong immunoreactivity for EGFR. The levels of expression of EGFR in choriocarcinoma and syncytiotrophoblasts and cytotrophoblasts in complete mole were significantly greater than those in syncytiotrophoblasts and cytotrophoblasts in both normal placenta and partial mole (P < 0.01, P < 0.01). Expression of c-erbB-3 did not significantly differ among placental and gestational trophoblastic disease tissues and trophoblastic cell types except for significantly increased expression in choriocarcinoma as compared with cytotrophoblasts of partial mole (P = 0.02). The placenta, complete and partial mole, and choriocarcinoma tissues demonstrated similar immunoreactivity for c-erbB-4. Strong immunostaining for EGFR (P = 0.02) and c-erbB-3 (P < 0.01) in extravillous trophoblasts of complete mole was found to be significantly correlated with the development of persistent postmolar gestational trophoblastic tumor., Conclusion: The EGFR-related family of oncogenes may be important in the pathogenesis of gestational trophoblastic diseases. The increased expression of EGFR and c-erbB-3 in complete mole may also influence the development of persistent gestational trophoblastic tumor., (Copyright 2000 Academic Press.)