Cadherins in malignancies of the female genital tract

Cadherins are a superfamily of adhesion molecules that mediate Ca++-dependent cell-cell adhesion necessary for normal morphogenesis and maintenance of tissue integrity. A classical cadherin molecule, such as E-cadherin, is a glycoprotein made up of three parts: an extracellular portion composed of five identical domains, a transmembrane portion composed of a single domain and a cytoplasmic portion composed of two domains. The cytoplasmic portion is anchored by means of cytoplasmic catenins to the cytoskeleton. The three amino acids sequence, histidine, alanine and valine (HAV motif) located at the most external domain of the extracellular portion, plays a key role in homophilic recognition between two cadherin molecules and cell-cell adhesion. Loss of cell-cell adhesion may be a prerequisite for malignant transformation and the invasive behavior of malignant tumors. Research of cadherin in malignancies has attracted much attention since cadherins may be proven to be reliable markers of biological behavior and prognosis The studies on cadherin in malignancies of the female genital tract have shown the following results: 1) in malignant transformation of the ovarian surface epithelium (OSE) and in epithelial ovarian carcinoma confined to the ovary (Stage I) there is a switch from N-cadherin expression to E-cadherin expression 2) In advanced-stage epithelial ovarian carcinoma (Stages II-IV) the results are at odds: some investigators have shown a loss of E-cadherin expression most often because of hypermethylation of the promoter region of the gene, while others have demonstrated an increase in E-cadherin expression 3) In endometrial carcinoma, E-cadherin expression is decreasing and P-cadherin expression is increasing with worsening of histologic type and differentiation, increased penetration into the myometrium, spread beyond the uterus and involvement of pelvic lymph nodes 4) In squamous cell carcinoma of the uterine cervix E-cadherin expression is decreasing with tumor progression and in adenocarcinoma of the uterine cervix P-cadherin expression is increasing with tumor progression. It is hoped that the development of drugs that amend cell-cell adhesion will improve the prognosis of patients in whom tumor progression is associated with decrease or loss of cadherin expression.