Both ␤-catenin and E-cadherin are epithelial cell adhesion molecules. In addition, ␤-catenin is an important element of the Wnt signal transduction pathway, which has been implicated in embryogenesis and carcinogenesis, including the development of endometrial and ovarian endometrioid carcinomas. We hypothesized that the expression pattern of these two adhesion molecules may depend upon the histological subtype of endometrial carcinomas. Therefore, we compared the immunohistochemical expression of ␤-catenin and E-cadherin in a set of uterine adenocarcinomas matched for high histologic grade, that is, poorly differentiated (International Federation of Gynecology and Obstetrics [FIGO] Grade III) uterine endometrioid carcinomas and uterine serous carcinomas. Seventeen FIGO Grade III endometrioid adenocarcinomas and 17 serous carcinomas were evaluated histologically and immunohistochemically with commercially available monoclonal antibodies against ␤-catenin and E-cadherin. Nuclear expression of ␤-catenin was observed in 8 of 17 (47%) endometrioid adenocarcinomas but in none of the serous carcinomas (P ‫؍‬ .003). Moderate or strong E-cadherin expression was identified in 7 of 17 (41%) serous carcinomas as opposed to in only 1 of 17 (6%) endometrioid adenocarcinomas (P ‫؍‬ .02). The majority of endometrioid adenocarcinomas showed strong ␤-catenin expression coupled with weak E-cadherin expression; serous carcinomas did not exhibit a comparable trend. Our results indicate that the expression of ␤-catenin and E-cadherin in high-grade endometrial cancers is strongly associated with histological subtype. These data provide further support for the distinct molecular profiles of endometrioid adenocarcinoma and serous carcinoma. Notably, differences in cell adhesion molecule expression could account for variations in patterns of tumor dissemination. The immunohistochemical staining pattern may also be useful for diagnostic purposes.

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Mutations in the Adenomatous Polyposis Coli (APC) tumor suppressor gene or the beta-catenin gene are present in most colon cancers and less frequently in other tumor types. In this study, we screened 24 human breast cancer cell lines and three immortalized human breast epithelial cell lines for alterations in beta- and gamma-catenin and APC by western blotting, protein truncation assay and DNA sequence analysis. In one cell line (DU 4475), an APC mutation was identified (E1577stop) that resulted in expression of truncated APC. This mutation was associated with elevated cytosolic beta-catenin levels, probably due to loss of APC function, as in colon cancers. No mutations were found in exon 3 of the beta- or gamma-catenin genes. We conclude that APC mutations and beta-catenin upregulation may occur with low frequency in human breast cancer cells.

The literature concerning serous borderline tumors with a noninvasive micropapillary component suggests an association with invasive implants. We compared the clinicopathologic features of micropapillary serous borderline tumors (MSBTs) with typical SBTs to determine the following: 1) the importance of focal micropapillary architecture in an otherwise typical SBT, 2) the behavior of low-stage MSBTs, 3) whether high-stage MSBTs are inherently more aggressive than high-stage SBTs, and 4) whether invasive implants are prevalent in an MSBT cohort without referral selection bias. The 57 borderline tumors studied were diagnosed at a university hospital between 1981 and 1998; they included 14 MSBTs, 35 SBTs, and 8 SBTs with focal micropapillary features. None of the specimens were referrals for expert pathologic consultation, thus distinguishing our study group from most of those previously reported. Neither MSBTs nor SBTs were associated with invasive implants at diagnosis (0 of 14 and 0 of 43, respectively). They also did not differ with respect to overall stage at diagnosis, but MSBTs were more frequently bilateral than SBTs (71% versus 23%, p = 0.001). There was an increased risk of recurrence in MSBT versus SBT (3 of 14 versus 1 of 43, p = 0.035), but this was stage related; there was no difference between groups when evaluating recurrence in stage I disease (0 of 8 versus 0 of 27). There was no difference in recurrence or stage at diagnosis between SBTs with focal micropapillary features and other SBTs. There was 100% survival in all groups. We conclude that high-stage MSBTs with noninvasive implants should be considered a subtype of SBTs with an increased risk of recurrence. Stage I MSBTs demonstrate clinical features that are similar to low-stage SBTs. Focal micropapillary architecture (<5 mm) has no bearing on outcome. MSBTs in the general population are not strongly associated with invasive implants.