In this study, we demonstrate that 1) loss of expression of both E-Cadherin and β-Catenin are frequent events in early stage cervical carcinomas of all three major histological subtypes, and both proteins are thus likely participants in the pathogenesis of cervical carcinoma, 2) Loss of expression of both proteins is of no prognostic significance with respect to the following parameters: recurrence free survival, overall survival, frequency of lymphovascular invasion, histologic grade, and frequency of lymph node involvement. Our findings are in concordance with the recent study of Van de Putte et al , in which cases of stage 1B SCC were analyzed. In that study, loss of expression of E-Cadherin and β-Catenin in greater than 50% of tumor cells was found in 90% and 72% of cases respectively. However, the authors found no correlation between the expression of E-Cadherin and β-Catenin (and other catenins) and prognosis . In contrast, Jeffers et al  found strong expression of E-Cadherin in all 20 cases of invasive cervical carcinoma that were studied. However, those 20 cases were an admixture of all stages and the prognostic significance of E-Cadherin was not specifically investigated since all cases were positive. Other studies have also showed a high frequency of loss of E-Cadherin expression in cervical cancers. Applying the criteria of the present study, impaired expression of E-cadherin was found in 89% of invasive SCCs in one study . In the study of Sun et al , 60 cases of invasive cervical carcinoma of all stages were investigated for E-cadherin expression. Loss of expression of E-Cadherin was found in 53.3% of cases. Additionally, the authors found a correlation between abnormal E-Cadherin expression and clinical stage and, in contrast to the present study, lymph node involvement and histologic grade. Similarly, among all stages of cervical adenocarcinoma, abnormal expression of β-Catenin was significantly associated with advanced pathologic stage and thus disease-free survival in another study . In the latter two studies, the noted discrepancies with the current one may be related to qualitative technical differences (antibody concentration, antigen retrieval methods etc) or differences in interpretation (i.e. criteria for positivity). None of the above studies have specifically compared the 3 major histologic subtypes in early stage cervical carcinoma. However, the majority of studies show that loss of expression of E-Cadherin and β-Catenin is frequent in cervical carcinomas. Although their impact on prognosis of this expression is less certain, our study finds that the expression of both E-Cadherin and β-Catenin lacks prognostic significance at least in early stage cervical carcinoma.
An orderly, membranous expression of E-Cadherin and β-Catenin is found in the normal cervix. The loss of expression of both proteins in a high proportion of high-grade squamous intraepithelial lesions [34–36] suggests that dysregulation of this pathway is an early event in cervical carcinogenesis. We investigated cytoplasmic and nuclear staining as a manifestation of impaired expression of both E-Cadherin and β-Catenin . In the typical normal cell β-Catenin's complex with E-Cadherin and the cytoskeletal network is inversely proportional to the association of β-Catenin with the adenomatous polyposis coli protein, a large multifunctional cytosolic protein. Thus, normally, only small portions of β-Catenin are found in the cytoplasm since the association of β-Catenin with APC eventuates in its lytic degradation. Cytoplasmic accumulation often leads to nuclear accumulation, where β-Catenin may interact with a variety of proteins, culminating in transcriptional activation of a variety of critical genes [23–26]. Experimental studies have shown that tyrosine phosphorylation of β-Catenin by oncogenic products or growth factor receptors may cause dissociation of the E-Cadherin-associated adhesion complex from the cytoskeleton resulting in cellular (non-membranous) redistribution and disassociation of adherens junctions, a well-known feature of epithelial malignancies [45, 46]. Exclusively cytoplasmic localization of β-Catenin and E-Cadherin, which was not present in any of the normal cervix epithelia, was seen in 3.4% and 5.4% of our carcinoma cases respectively. A progressive increase in the proportion of cases showing this finding was found in low grade SIL, high grade SIL and invasive carcinomas in one study . However, the logical extension of that finding, a correlation with histological grade in invasive carcinomas, was not found in this study. Our study is also in concordance with that of Shinohara et al , in which no relationship was found between the frequency of cytoplasmic/nuclear localization of β-Catenin and histologic grade (no cases of nuclear localization β-Catenin was found in our study).
The possibility that our findings may have been significantly affected by our methods cannot be entirely excluded. Tissue microarray technology as a high throughput modality has gained wide acceptance in pathology investigations and is used routinely [48–52]. Our TMA was constructed with a two-fold redundancy to minimize sampling errors . Furthermore, in our validation set which constituted approximately 10% of the TMA, no significant discrepancies were seen. Nonetheless, error introduced by tumor heterogeneity remains a possibility. Most notably, the minimization of errors from the redundant (2-fold) construction of our TMA presumes a similar degree of tumor heterogeneity between breast  and cervical cancer, which may be untrue.
The importance of defining thresholds in any investigations reporting the loss of the immunohistochemical expression of a biomarker cannot be overemphasized. As previously noted, a threshold of 200 was used in this study because both E-Cadherin and β-Catenin are normally expressed in a membranous fashion in most of the cervical epithelium (scores 270–300 for the ectocervix and 300 for the endocervix). However, we performed separate statistical analyses when the threshold was lowered, i.e. when "impaired" expression included any of the following: negative staining, a score less than 99, or exclusively cytoplasmic and/or nuclear delocalization. The results on all previous analyses remained the same (p > 0.05), with 2 exceptions: 1) Overall, the expressions of E-Cadherin and β-Catenin became significantly correlated (spearman correlation coefficient r = 0.33, p = 0.0001). 2) 73% of LVI-negative carcinomas showed impaired β-Catenin expression, compared to 47% of LVI-positive carcinomas (p = 0.03). The significance of the latter finding is unclear, and it can be anticipated that changes in the threshold in either direction (lowering or raising) would result in at least one parameter attaining statistical significance with each change. In our opinion, for a marker that is normally expressed, a high threshold should be used for "loss" of expression, and 200/300 seems reasonable.