Cell cycle-related proteins p21 and bcl-2: markers of differentiation in the human fallopian tube

The conceptual advances of carcinogenic sequence model in high-grade serous ovarian cancer

The present review focuses on the current status of molecular pathology in high-grade serous cancer (HGSC) and preneoplastic conditions. This article reviews the English-language literature on HGSC, precursor, fallopian tubal epithelium, secretory cells, ciliated cells, secretory cell expansion, secretory cell outgrowth (SCOUT), p53 signature, serous tubal intraepithelial carcinoma (STIC), DNA damage and immunohistochemistry in an effort to identify the precursor-carcinoma sequence in HGSC. The majority of HGSC originates from the fimbriated end of the fallopian tube secretory epithelial cells, while the small part of this disease may develop from ovarian cortical inclusion cyst (CIC). A series of morphological changes from normal fallopian epithelium to preneoplastic to neoplastic lesions were concomitant with the multistep accumulation of molecular and genetic alterations. Recent studies provide a stepwise progression of fallopian tubal epithelium to precursor lesions to carcinoma, with the aid of a 'secretory cell-SCE-SCOUT-p53 signature-STIC-HGSC sequence' model. Immunohistochemical markers, including p53, STMN1, EZH2, CCNE1, Ki67 and γ-H2AX, were gradually increased during the SCOUT-p53 signature-STIC-HGSC sequence. Conversely, PAX2 expression was decreased during the early phase of SCOUT development. Potential genes and proteins are involved in the evolutionary trajectory of the precursor-cancer lineage model. In the present review we examined detailed aspects of the molecular changes involved in malignant transformation from fallopian tube epithelium to HGSC. A precursor condition originating in 'field cancerization' may gain a growth advantage, leading to HGSC.

A patient-derived-xenograft platform to study BRCA-deficient ovarian cancers

Approximately 50% of high-grade serous ovarian cancers (HGSOCs) have defects in genes involved in homologous recombination (HR) (i.e., BRCA1/2). Preclinical models to optimize therapeutic strategies for HR-deficient (HRD) HGSOC are lacking. We developed a preclinical platform for HRD HGSOCs that includes primary tumor cultures, patient-derived xenografts (PDXs), and molecular imaging. Models were characterized by immunohistochemistry, targeted sequencing, and reverse-phase protein array analysis. We also tested PDX tumor response to PARP, CHK1, and ATR inhibitors. Fourteen orthotopic HGSOC PDX models with BRCA mutations (BRCA^MUT) were established with a 93% success rate. The orthotopic PDX model emulates the natural progression of HGSOC, including development of a primary ovarian tumor and metastasis to abdominal viscera. PDX response to standard chemotherapy correlated to that demonstrated in the patient. Pathogenic mutations and HGSOC markers were preserved after multiple mouse passages, indicating retention of underlying molecular mechanisms of carcinogenesis. A BRCA2^MUT PDX with high p-CHK1 demonstrated a similar delay of tumor growth in response to PARP, CHK1, and ATR inhibitors. A poly (ADP-ribose) polymerase (PARP) inhibitor radiotracer correlated with PARP1 activity and showed response to PARP inhibition in the BRCA2^MUT PDX model. In summary, the orthotopic HGSOC PDX represents a robust and reliable model to optimize therapeutic strategies for BRCA^MUT HGSOC.

Ovarian Cancer Is an Imported Disease: Fact or Fiction?

The cell of origin of ovarian cancer has been long debated. The current paradigm is that epithelial ovarian cancer (EOC) arises from the ovarian surface epithelium (OSE). OSE is composed of flat, nondescript cells more closely resembling the mesothelium lining the peritoneal cavity, with which it is continuous, rather than the various histologic types of ovarian carcinoma (serous, endometrioid, and clear cell carcinoma), which have a Müllerian phenotype. Accordingly, it has been argued that the OSE undergoes a process termed "metaplasia" to account for this profound morphologic transformation. Recent molecular and clinicopathologic studies not only have failed to support this hypothesis but also have provided evidence that EOC stems from Müllerian-derived extraovarian cells that involve the ovary secondarily, thereby calling into question the very existence of primary EOC. This new model of ovarian carcinogenesis proposes that fallopian tube epithelium (benign or malignant) implants on the ovary to give rise to both high-grade and low-grade serous carcinomas, and that endometrial tissue implants on the ovary and produces endometriosis, which can undergo malignant transformation into endometrioid and clear cell carcinoma. Thus, ultimately EOC is not ovarian in origin but rather is secondary, and it is logical to conclude that the only true primary ovarian neoplasms are germ cell and gonadal stromal tumors analogous to tumors in the testis. If this new model is confirmed, it has profound implications for the early detection and treatment of "ovarian cancer."

The Li-Fraumeni syndrome (LFS): a model for the initiation of p53 signatures in the distal Fallopian tube

A candidate early precursor to pelvic serous cancer, the 'p53 signature', is commonly found in the benign mucosa of the distal Fallopian tube and harbours p53 mutations and evidence of DNA damage. We examined tubes from women with pre-existing (germ-line) mutations in p53 [Li-Fraumeni syndrome (LFS)] for evidence of this precursor. Fallopian tubes from two cases of LFS were immunostained for p53, Ki-67 (proliferation) and H2AX (DNA damage response) and analysed for p53 mutations by laser capture microdissection (LCM) and p53 genomic sequencing (exons 2-11). A common single nucleotide repeat (snp) in exon 3 (rs1042522) and deletion sequencing chromatograms in exon 4 were examined in combination to estimate LOH in both LFS tubes and advanced serous carcinomas from the general population. LFS tubal epithelium contained abundant (10-20 per section) p53 signatures with evidence of DNA damage and low proliferative activity. Six of 11 LFS microdissected p53 signatures (55%) and 15 of 21 serous carcinomas (71%) revealed LOH at the p53 locus, relative to background epithelium. The LFS model confirms prior observations that the distal Fallopian tube is particularly prone to focal epithelial p53 gene inactivation-p53 mutation and LOH-in the absence of malignancy or increased epithelial proliferation. The fact that the LFS is not associated with ovarian cancers is consistent with the concept that loss of p53 function must be accompanied by at least one more genotoxic event (including BRCA1/2 functional inactivation) to produce the malignant phenotype. This is in keeping with a general model of carcinogenesis, in which different and often independent risk factors operate at multiple points in the serous carcinogenic spectrum.

Primary ex vivo cultures of human fallopian tube epithelium as a model for serous ovarian carcinogenesis

Recent studies suggest that some serous ovarian carcinomas (SOCs) arise from the fallopian tube (FT) epithelium rather than the ovarian surface epithelium. This hypothesis places emphasis on the FT secretory epithelial cell as a cell-of-origin. Herein, we report the development of a novel ex vivo primary human FT epithelium culture system that faithfully recapitulates the in vivo epithelium, as shown by morphological, ultrastructural and immunophenotypic analyses. Mass spectrometry-based proteomics reveal that these cultures secrete proteins previously identified as biomarkers for ovarian cancer. We also use this culture system to study the response of the FT epithelium to genotoxic stress and find that the secretory cells exhibit a distinct response to DNA damage when compared with neighboring ciliated cells. The secretory cells show a limited ability to resolve the damage over time, potentially leaving them more susceptible to accumulation of additional mutagenic injury. This divergent response is confirmed with in situ studies using tissue samples, further supporting the use of this ex vivo culture system to investigate FT epithelial pathobiology. We anticipate that this novel culture system will facilitate the study of SOC pathogenesis, and propose that similar culture systems could be developed for other organ site-specific epithelia.

New insights into the pathogenesis of serous ovarian cancer and its clinical impact

There are only a handful of concepts concerning cancer and carcinogenesis that are currently beyond dispute. One such dogma is the adenoma-carcinoma sequence and that a multistep accumulation of genetic alterations is required for transformation from a benign to a neoplastic tissue. The inevitable derivative of this dogma is that every invasive carcinoma is in fact a missed intraepithelial tumor, and furthermore, a late evolutionary stage in the sequence of development from a precursor lesion. Until fairly recently, high-grade serous ovarian carcinoma seemed to be one of the only known deviants of these concepts. In this article, we discuss the emergence of the fallopian tube fimbria as a field of origin for high-grade serous carcinomas and present a binary model of ovarian cancer pathogenesis that takes into consideration prior epidemiologic, morphologic, and genetic data. With the rise of the fallopian tube secretory epithelial cell as a cell of origin for high-grade pelvic serous carcinomas, the need to develop tools and model systems to characterize the biology and physiology of this cell is recognized.

Differential expression of cyclin-dependent kinase inhibitors and apoptosis-related proteins in endocervical lesions

The development of neoplasia is associated with abnormalities of cell cycle control and apoptosis. In this study, a panel of cyclin-dependent kinase inhibitors (CDKIs) and apoptosis-related proteins (p16, p21, p53, Bcl2 and hsp27) was analysed by immunohistochemistry in 91 glandular cervical lesions. A significant increase in p21 and p53 expression occurred from normal cervix (n=11) through endometriosis/tubo-endometrioid metaplasia (TEM) (n=19) and cervical glandular intraepithelial neoplasia (CGIN)/adenocarcinoma in situ (AIS) (n=33) to invasive adenocarcinoma (n=28). p16 showed diffuse strong expression in CGIN/AIS and invasive adenocarcinoma compared with focal expression in some TEM/endometriosis lesions and no expression in normal cervix. Bcl2 was highly expressed in TEM/endometriosis compared with CGIN/AIS and adenocarcinoma. p16 immunostaining discriminated accurately between neoplastic and non-neoplastic cervical lesions, provided that diffuse strong positivity was present. Similarly, diffuse expression of Bcl2 distinguished endometriosis/TEM from CGIN/AIS. These data demonstrate that analysis of CDKIs and apoptosis-related proteins provides useful information in the diagnostic assessment of glandular lesions of the cervix.

Emerging roles for PAX8 in ovarian cancer and endosalpingeal development

OBJECTIVES

Epithelial ovarian carcinomas develop from ovarian surface epithelia that undergo complex differentiation to form distinguishable phenotypes resembling those of the epithelia of the female urogenital regions. While previous studies have implicated regulatory developmental homeobox (HOX) genes in this process, other factors responsible for this differentiation are largely unknown. Aberrant transcriptional expression of PAX8 has been reported in epithelial ovarian cancer, prompting us to initiate the molecular characterization of this master regulatory gene in ovarian cancer development.

METHODS

Immunohistochemistry, immunoblotting and RT-PCR were used to investigate the presence of PAX8 and its protein products in epithelial ovarian cancer subtypes, normal ovarian surface epithelia, ovarian inclusion cysts and normal endosalpingeal epithelia.

RESULTS

In this report, we confirm microarray results indicating that the transcription factor, PAX8, is highly expressed in epithelial ovarian cancer but absent from the precursor ovarian surface epithelia of healthy individuals. Furthermore, we report that PAX8 is localized to the nucleus of non-ciliated epithelia in simple ovarian epithelial inclusion cysts and in three epithelial ovarian cancer subtypes (serous, endometrioid and clear cell). We also determined that PAX8 is expressed in the non-ciliated, secretory cells of healthy fallopian tube mucosal linings but not in the adjacent ciliated epithelia.

CONCLUSION

These findings support the hypothesis that PAX8 plays parallel roles in the development of epithelial ovarian cancer and in the developmental differentiation of coelomic epithelia into endosalpingeal epithelia.

Changes in the ratio of Bax and Bcl-2 mRNA expression and their cellular localization throughout the ovulatory cycle in the human oviduct

PURPOSE

To examine changes in the ratio of Bax and Bcl-2 mRNA expression throughout the ovulatory cycle in the ampullary region of the human oviduct.

METHODS

The mucosal layer was isolated from the human oviduct tissue and semiquantitative reverse-transcriptase polymerase chain-reaction (RT-PCR) analysis of mRNA of Bax and Bcl-2 was performed. Immunohistochemistry provided the cellular localization of the Bax and Bcl-2 proteins. The ratio of expression of Bax and Bcl-2 mRNA was examined in the ampullary region of the oviduct in samples obtained in the follicular, periovulatory, and luteal phases of the ovulatory cycle.

RESULTS

Bax expression was constant in the follicular and periovulatory phase but showed a significant increase in the luteal phase. The Bax protein was present in all oviduct mucosal epithelial cells and the intensity of staining increased in luteal phase samples. Bcl-2 was expressed at a relatively constant level throughout the ovulatory cycle. The Bcl-2 protein was present in some but not all mucosal epithelial cells and the proportion of positive cells remained constant throughout the ovulatory cycle.

CONCLUSION

The proapoptotic gene Bax shows a significant increase in mRNA expression in the luteal phase of the ovulatory cycle while the expression level of the antiapoptotic gene Bcl-2 remains constant throughout the ovulatory cycle. The ratio of Bax:Bcl-2 increases significantly in the luteal phase consistent with cells undergoing apoptosis.

Intraperitoneal serous adenocarcinoma: a critical appraisal of three hypotheses on its cause

OBJECTIVE

Serous ovarian, Fallopian tube, and peritoneal adenocarcinomas are remarkably similar, both in their morphology, as well as in their clinical behavior. Despite extensive clinical and fundamental research, controversy still exists on the origin of serous female adnexal tumors. Difficulties in identification of site of origin at late stage the of disease at detection, when ovary, Fallopian tube, and the abdominal cavity are usually all involved, in addition to their macroscopic and microscopic resemblance, are major causes of this debate. In 3 hypotheses, 3 possible tissues of origin are proposed: the ovarian surface epithelium, the Fallopian tube epithelium, and the secondary Mullerian system.

STUDY DESIGN

We searched for all peer-reviewed articles and reviews that examined "serous ovarian carcinoma," "Fallopian tube carcinoma," "Mullerian system," "ovarian surface epithelium," "tubal epithelium," and "peritoneal." We included only articles that could give information on the origin of serous carcinomas. Additional articles were added by examining references of overview articles in relevant fields.

RESULTS

Discussed are the experimental data underlying these hypotheses.

CONCLUSION

An attempt is made to integrate the 3 hypotheses into a comprehensive model of serous intraperitoneal adenocarcinogenesis. It can be concluded that the Fallopian tubes play a major role in the development of female serous cancer.

VDUP1 upregulated by TGF-beta1 and 1,25-dihydorxyvitamin D3 inhibits tumor cell growth by blocking cell-cycle progression

Vitamin D(3) upregulated protein 1 (VDUP1) is a 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) upregulated protein, and it is induced by various stresses. In human tumor tissues, VDUP1 expression was downregulated. Upon stimulation by growth-inhibitory signals such as TGF-beta1 and 1,25(OH)(2)D(3), its expression was rapidly upregulated as the cell growth was retarded. The transfection of VDUP1 in tumor cells reduced cell growth. The VDUP1 expression was also increased when the cell-cycle progression was arrested. Transfection of VDUP1 induced cell-cycle arrest at the G0/G1 phase, indicating that VDUP1 possesses a tumor-suppressive activity. In addition, it was found that VDUP1 interacted with promyelocytic leukemia zinc-finger, Fanconi anemia zinc-finger, and histone deacetylase 1, which are known to be transcriptional corepressors. VDUP1 itself suppressed IL-3 receptor and cyclin A2 promoter activity. Taken together, these results suggest that VDUP1 is a novel antitumor gene which forms a transcriptional repressor complex.

Endocervical glandular lesions: controversial aspects and ancillary techniques

The incidence of malignant and premalignant endocervical glandular lesions is increasing. This review covers controversial and difficult aspects regarding the categorisation and diagnosis of these lesions. The terminology of premalignant endocervical glandular lesions is discussed because of the differences between the UK terminology and the widely used World Health Organisation classification. The morphology and histological subtypes of premalignant endocervical glandular lesions are described. Early invasive adenocarcinoma and difficulties in the diagnosis and recognition of this entity are covered, as is the measurement of early invasion within cervical adenocarcinoma. Several benign endocervical glandular lesions can mimic malignant and premalignant endocervical glandular lesions, and the distinction of these benign mimics from premalignant and malignant lesions using ancillary immunohistochemical studies is also covered. Antibodies used to distinguish between endometrial and endocervical adenocarcinoma, in the diagnosis of cervical minimal deviation adenocarcinoma of mucinous type (adenoma malignum), and in the diagnosis of cervical mesonephric lesions are also reviewed.

Immunohistochemical staining with MIB1, bcl2 and p16 assists in the distinction of cervical glandular intraepithelial neoplasia from tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia

AIMS

Preinvasive endocervical glandular lesions, termed cervical glandular intraepithelial neoplasia, are increasing in incidence. The distinction of cervical glandular intraepithelial neoplasia from benign mimics, especially tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia, can be difficult. This study investigates the value of immunohistochemical staining with MIB1, bcl2 and p16 in the distinction of cervical glandular intraepithelial neoplasia from these benign mimics.

METHODS AND RESULTS

Immunohistochemical staining using the monoclonal antibodies MIB1, bcl2 and p16 was performed on cases of cervical glandular intraepithelial neoplasia (n = 21), tubo-endometrial metaplasia (n = 13), endometriosis (n = 7) and microglandular hyperplasia (n = 14). With tubo-endometrial metaplasia and microglandular hyperplasia staining with MIB1 was either negative or involved <10% of cells, while with cervical glandular intraepithelial neoplasia the majority of cases (86%) exhibited >10% positive cells. Two cases of endometriosis exhibited a MIB1 index of 10-30% while in the other cases <10% cells stained. With bcl2 the cells of microglandular hyperplasia were negative although there was staining of associated reserve cells in 43% of cases. All cases of tubo-endometrial metaplasia except one and all cases of endometriosis stained diffusely positive with bcl2. Cases of cervical glandular intraepithelial neoplasia were negative or exhibited focal staining. With p16 all cases of cervical glandular intraepithelial neoplasia exhibited diffuse strong positivity, generally involving 100% of cells, while all cases of microglandular hyperplasia were negative. Sixty-two percent of cases of tubo-endometrial metaplasia showed focal positivity, the remainder being negative. Cases of tubo-endometrial metaplasia were never diffusely positive with p16. In three cases of endometriosis there was staining of >50% of cells while the other cases were either focally positive or negative.

CONCLUSIONS

A panel of antibodies, comprising MIB1, bcl2 and p16, is a useful adjunct to histology in distinguishing cervical glandular intraepithelial neoplasia from tubo-endometrial metaplasia, endometriosis and microglandular hyperplasia. Cases of cervical glandular intraepithelial neoplasia are diffusely positive for p16 and generally exhibit a high proliferation index with MIB1, while bcl2 is negative or, at most, focally positive. Tubo-endometrial metaplasia and endometriosis are characterized by strong diffuse positivity with bcl2 and a low proliferation index with MIB1 (although occasional cases of endometriosis show moderate proliferative activity). p16 is negative or exhibits focal positivity in tubo-endometrial metaplasia but in endometriosis there may be quite widespread positivity. Microglandular hyperplasia shows a low proliferation index with MIB1 and is negative for bcl2 and p16.