Molecular and Pathologic Aspects of Endometrial Carcinogenesis

Activity of lapatinib a novel HER2 and EGFR dual kinase inhibitor in human endometrial cancer cells

In this study, we explore the therapeutic potential of lapatinib a selective inhibitor of both the EGFR and HER2 tyrosine kinases for the treatment of endometrial cancer. The effect of lapatinib on tumour cell growth and receptor activation was studied in a panel of human endometrial cancer cell lines. Candidate molecular markers predicting sensitivity were assessed by baseline gene expression profiling, ELISA, and western blot analyses. Multiple drug effect/combination index (CI) isobologram analysis was used to study the interactions between chemotherapeutic drugs and lapatinib. Concentration-dependent anti-proliferative effects of lapatinib were seen in all endometrial cancer cell lines tested, but varied significantly between individual cell lines (IC₅₀ range: 0.052–10.9 μmol). HER2 overexpression or increased expression of EGFR was significantly associated with in vitro sensitivity (P=0.024 or 0.011, respectively). Lapatinib exerts growth inhibition in a PTEN-independent manner. Sensitive cell lines also exhibited increased expression of EGFR ligands or HER3. In contrast, lapatinib-resistant cell lines exhibited high androgen receptor (AR) levels or epithelial-to-mesenchymal transition (post-EMT) features. In endometrial cancer cells, at a wide range of clinically achievable drug concentrations, additive and synergistic interactions were observed for lapatinib plus carboplatin, paclitaxel, docetaxel, and doxorubicin. These observations provide a clear biologic rational to test lapatinib as a single agent or in combination with chemotherapy in endometrial cancer with HER2 overexpression. Expression of EGFR, its ligands, HER3, AR, and post-EMT markers warrant further evaluation to help define patients with HER2-nonoverexpressing endometrial cancer most likely to benefit from lapatinib.

Claudin-3 and claudin-4 expression in serous papillary, clear-cell, and endometrioid endometrial cancer

OBJECTIVE

Tight junction (TJ) proteins claudin-3 and claudin-4 may be differentially expressed in uterine serous papillary carcinoma (USPC), a rare form of endometrial cancer characterized by a particularly poor prognosis. Our aim was to determine the expression pattern and prognostic relevance of claudin-3 and claudin-4 in a large cohort of endometrial cancer patients of diverse histological type and stage.

METHODS

Claudin-3 and claudin-4 expression was studied in a cohort of 287 patients with endometrial cancer including 137 cases of USPC or clear-cell histology using immunohistochemistry. Patients were completely surgically staged. Outcome data is available on all 287 patients.

RESULTS

The rate of claudin-3 and claudin-4 expression was significantly higher in USPC and clear-cell endometrial cancer compared to endometrioid endometrial cancer (claudin-3: 78% and 61% versus 38%, p<.0001; claudin-4: 56% and 44% versus 9%, p<.0001). Furthermore, expression of both TJ proteins was significantly associated with poor clinical outcome (claudin-3, DFS RR 1.70, p=.0087, OS RR 1.62, p=.0247; claudin-4, DFS RR 2.66, p<0.0001, and OS RR 2.50, p<0.0001). However, both markers did not maintain prognostic independence in multivariate analyses, as their expression was tightly associated with more advanced disease stages (p<.0001 for both), and higher nuclear grade (p<.0001 for both).

CONCLUSION

These clinical observations confirm the hypothesis based on preclinical evidence that increased expression of claudin-3 and claudin-4 may contribute to the aggressive phenotype of endometrial cancer of serous papillary or clear-cell histology and suggest their potential utility as diagnostic biomarkers and possible targets for therapeutic intervention.

Management of abnormal uterine bleeding and the pathology of endometrial hyperplasia

There are no screening tests for endometrial carcinoma, and patients typically present with abnormal uterine bleeding. This article discusses the pathophysiology and clinical work-up of abnormal uterine bleeding, and risk factors for endometrial carcinoma. Atypical complex hyperplasia and the more recently defined endometrial intraepithelial neoplasia are well recognized as precancers. Evolving knowledge of their genetic alterations provides the opportunity to develop molecular markers, so that endometrial diseases may be diagnosed at the precancerous or early invasive stage. Emerging molecular markers also provide the opportunity to develop clinically useful screening tests for the most common malignancy of the female genital tract.

Endometrial Glandular Dysplasia (EmGD): morphologically and biologically distinctive putative precursor lesions of Type II endometrial cancers

In this article, the authors briefly review the historical evolution of the various putative precursor lesions for Type II endometrial cancers, with an emphasis on the newly defined "Endometrial Glandular Dysplasia (EmGD)". The evidentiary basis for delineating serous EmGD as the most probable precursor lesions to endometrial serous carcinoma is reviewed in detail. An argument is advanced for the discontinuation of the term serous "endometrial intraepithelial carcinoma (EIC)" as a descriptor for a supposedly intraepithelial, precancerous lesion. Preliminary evidence is also presented that suggests that there is a morphologically recognizable "clear cell EmGD" that probably represents a precancerous lesion to endometrial clear cell carcinomas.

EGF-receptor targeting with monoclonal antibodies in colorectal carcinomas: rationale for a pharmacogenomic approach

Monoclonal antibodies directed against the EGF-receptor (EGFR) have recently been approved for the treatment of metastatic colorectal cancer (CRC) patients with EGFR-positive tumors at immunohistochemistry (IHC). Surprisingly, data demonstrate a lack of correlation between the tumor’s EGFR expression at IHC and outcome. Indeed, as pointed out from small experiences, patients with EGFR-IHC-negative metastatic CRC have the same chance as EGFR-IHC-positive patients to benefit from an anti-EGFR monoclonal antibody, underlying the importance of different, more reliable, selection criteria. In particular, the identification of such predictive factors is important as these agents are expensive, have side effects and are really only effective in a minority of patients. Several potential clinical and biological predictive markers of activity and/or efficacy for such agents have been evaluated in retrospective series with promising results. Moving from clinical data suggesting that there could be a subpopulation of CRC patients that are more liable to benefit from anti-EGFR monoclonal antibodies, here we review major studies on determinants of outcome in this field.

Endometrial carcinoma recurring as carcinosarcoma: Report of two cases

Endometrial carcinosarcoma is a rare, aggressive disease, accounting for approximately 3% of all uterine neoplasms. The emergence of sarcomatous elements is considered the evolution of subclones arising from high grade endometrial carcinomas. Here, we report two cases of primary endometrial carcinomas recurring as carcinosarcoma. Case 1. a 58-year-old postmenopausal woman diagnosed to have a poorly differentiated endometrial endometrioid adenocarcinoma (FIGO stage IB) developed an intra-abdominal recurrence of disease after 17 months from diagnosis. Histopathological analysis documented a biphasic neoplasia consisting of an epithelial (grade 3 endometrial endometrioid adenocarcinoma) and a sarcomatous component. Salvage chemotherapy with cisplatin, ifosfamide, epirubicin, and then with taxotere was attempted. The patient died after 2 months. Case 2. A 56-year-old woman with a diagnosis of grade 3 endometrial adenosquamous carcinoma of the endometrium (FIGO stage IIIA) experienced pelvic recurrence after five months from completion of chemotherapy. Definitive histology was malignant mixed mesodermal tumor with focal areas of chondrosarcomatous elements. The patient was triaged to exclusive concomitant chemoradiotherapy and salvage chemotherapy. The patient died after 3 months. We describe two cases of high grade endometrial carcinomas recurring as carcinosarcoma, thus providing evidence that the metaplastic sarcomatous evolution is a very rare event which can occur in patients with anaplastic endometrial cancer.

Hormone therapy in advanced and recurrent endometrial cancer: a systematic review

Endometrial cancer is a hormone-dependent malignancy, and the majority has a precursor phase of endometrial hyperplasia. Histologic subtypes have been recognized with differing natural history. The relationship between hormone response, histology, and molecular profile is not established, but the relevant biology is summarized. This study was a systematic review of the literature to identify which populations should be considered for hormone interventions. Systematic searches were carried out in the English literature for randomized controlled trials and phase II studies of hormone interventions in endometrial cancer. Five randomized trials and 29 phase II studies were identified comprising a total of 2471 patients. In previously untreated patients with grade 1 (G1) or G2 tumors, the response rate for progestogens and the progression-free survival is in the range of 11–56% and 2.5–14 months, respectively. Higher response rates are seen in progesterone receptor–positive cases. Phase II studies comprise the majority of the data and many are of poor quality. There was considerable heterogeneity in patient selection, prior treatment, and type of regimen, and meta-analysis was not possible. G3 or G4 toxicity was less than 5%. We conclude that hormone receptor assessments should be carried out in all patients entered on clinical trials and may aid clinical management in selected cases. Receptor-negative status should not be an absolute contraindication to hormone intervention. Integration of hormone treatment with conventional chemotherapy and growth factor–targeted therapy needs to be explored.

Liquid-based Papanicolaou test (SurePath) interpretations before histologic diagnosis of endometrial hyperplasias and carcinomas

BACKGROUND

In addition to the reporting of atypical glandular cells (AGC) and adenocarcinoma (ADCA), the 2001 Bethesda System requires the reporting of benign-appearing endometrial cells in women aged >40 years (BAEMC). In this study, the authors evaluated the contribution of each of these reporting categories to the sensitivity and specificity of a liquid-based Papanicolaou test for endometrial carcinoma or hyperplasia.

METHODS

Over the 3-year study period, in the setting of a large, multihospital health care system, the authors analyzed the results from liquid-based Papanicolaou tests that were performed within the 6 months that preceded a histologic diagnosis of endometrial carcinoma or hyperplasia and that were reported according to the 2001 Bethesda System.

RESULTS

Two hundred seventy-two women had a histologic diagnosis of endometrial hyperplasia (n = 199) or malignancy (n = 73) within 6 months after a Papanicolaou test. In total, 188,594 Papanicolaou tests (91,385 from women aged >40 years) were interpreted during the study period and resulted in 3810 diagnoses of BAEMC, 326 diagnoses of AGC, and 30 diagnoses of ADCA. Only 28 of 73 women (38.4%) with endometrial carcinoma had cytologically AGC or ADCA reported on a previous Papanicolaou test. The reporting of BAEMC increased this sensitivity by only 5.5% (4 additional tests) but decreased the specificity of the Papanicolaou test for endometrial malignancy from 99.8% to 96%. For endometrial hyperplasias, the sensitivity of the Papanicolaou test was even lower (39 of 198 tests; 19.7%), but BAEMC represented the majority of endometrial-type cells reported (36 of 39 tests).

CONCLUSIONS

The reporting of BAEMC led to an only marginal increase in sensitivity that had to be weighed against the significant loss in specificity of the Papanicolaou test for endometrial neoplasia.

Comprehensive annotation of bidirectional promoters identifies co-regulation among breast and ovarian cancer genes

A “bidirectional gene pair” comprises two adjacent genes whose transcription start sites are neighboring and directed away from each other. The intervening regulatory region is called a “bidirectional promoter.” These promoters are often associated with genes that function in DNA repair, with the potential to participate in the development of cancer. No connection between these gene pairs and cancer has been previously investigated. Using the database of spliced-expressed sequence tags (ESTs), we identified the most complete collection of human transcripts under the control of bidirectional promoters. A rigorous screen of the spliced EST data identified new bidirectional promoters, many of which functioned as alternative promoters or regulated novel transcripts. Additionally, we show a highly significant enrichment of bidirectional promoters in genes implicated in somatic cancer, including a substantial number of genes implicated in breast and ovarian cancers. The repeated use of this promoter structure in the human genome suggests it could regulate co-expression patterns among groups of genes. Using microarray expression data from 79 human tissues, we verify regulatory networks among genes controlled by bidirectional promoters. Subsets of these promoters contain similar combinations of transcription factor binding sites, including evolutionarily conserved ETS factor binding sites in ERBB2, FANCD2, and BRCA2. Interpreting the regulation of genes involved in co-expression networks, especially those involved in cancer, will be an important step toward defining molecular events that may contribute to disease.

Promoters are regulatory regions that control transcription of genes. A special class of promoters, known as bidirectional promoters, regulates expression of two genes instead of one. These promoters are situated between two adjacent genes whose transcription start sites are physically within 1,000 bp and oriented in opposite directions. Bidirectional promoters are found repeatedly in the genome, suggesting an important biological significance for this regulatory configuration. We developed an algorithm to map bidirectional promoters using data from a comprehensive list of transcribed sequences known as expressed sequence tags, or ESTs. This approach improved the number of previously characterized bidirectional promoters by 300%. Included in the new data are bidirectional promoters that regulate expression of genes implicated in somatic cancers. For instance, ten well-recognized genes implicated in breast and ovarian cancers were identified as having bidirectional promoters. Three of the genes are further related by having duplicate copies of the same binding site for a transcription factor within their bidirectional promoters. These binding sites are conserved among species, providing greater evidence that they are functionally important. This example, in which similar regulatory structures are used to control genes involved in cancer, illustrates how data can be mined from the comprehensive set of bidirectional promoters. Within this manuscript, we show statistical evidence that many cancer genes are regulated by bidirectional promoters. These promoters will be a valuable dataset for studying the role of gene regulation in tumor development.

Recent developments in colorectal cancer treatment by monoclonal antibodies

A growing understanding of the molecular mechanisms involved in cancer biology and continuous refinement of available technologies for drug discovery have prompted the development of new therapeutic tools targeting specific cancer-associated molecular pathways. Among these so-called biological therapies, monoclonal antibodies have now reached the time of clinical application. Besides initial development of the murine antibody edrecolomab, the impact of monoclonal antibodies on cancer therapy has recently been clearly demonstrated in colorectal cancer by targeting two major pathways critical to tumourigenesis: the epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) signalling pathways. These antibodies showed significant clinical activity in advanced colorectal cancer, especially when combined with chemotherapy. This paper reviews the status of the monoclonal chimeric antibody cetuximab (Erbitux) and other anti-EGFR antibodies, and of bevacizumab (Avastin; an anti-VEGF humanised monoclonal antibody), in colorectal cancer treatment.