CD44 as a differentiation marker and metastasis promoter in gynecological malignancies

CD44 has been established as a major player in the development and metastatic spread of various human malignancies due to its adhesional properties. However, the concept of CD44 as a universal metastasis promoter has been brought into question by the fact that the expression of CD44 isoforms lacks prognostic value in several malignancies, e.g. ovarian cancer, endometrial cancer, and breast cancer. Furthermore, CD44 isoform expression has been shown to be downregulated after malignant transformation of certain cell types (58) (59). It may be speculated that the role of CD44 as a metastasis mediator in hormonally regulated malignancies, e.g., breast and ovarian cancer, is impaired by hormonal interference with the biological functions of CD44. On the other hand, CD44 expression is not correlated with hormonal phenotypes in neuroendocrine tumours and has been shown to be independent of estrogen and progesterone receptor status in breast cancer (60) (61). In the field of gynecological oncology, CD44 is most likely to be at the center of scientific attention in cervical cancer. Assessment of CD44 isoform expression could be of clinical value in deciding about adjuvant therapy resulting in more individualized therapy management. According to the data available today, theCD44 isoform CD44v6 is the most promising candidate to become an additional prognostic marker in surgically treated cervical cancer.