Homeostasis in normal tissue is regulated by a balance between proliferative activity and cell loss by apoptosis [
1,
2]. Attachment to correct extracellular matrix (ECM) is essential for survival and growth of normal adhering cells, whereas cancer cells are able to abrogate this requirement. Several growth factors and cytokines play pivotal roles in the regulation of growth and survival of neoplastic cells through affecting integrin-mediated adhesion to ECM.
Cell adhesion molecules are important mediators of cellular contacts and cellular polarity that also modulate proliferation, differentiation, and invasion. Osteopontin (OPN) is a 70-kDa secreted extracellular matrix glycoprotein with an arginine-glycine aspartate-binding motif capable of interaction with integrin subunits [
3‐
5]. Both OPN and CEACAM5 are important cell adhesion molecules. OPN has been demonstrated to be expressed in a variety of human tissues, including the kidneys, thyroid, gastrointestinal tract, breast, and endometrium, and has been implicated in mediation of cell-cell and cell-extracellular matrix communication that encompass both normal and tumorigenic developmental processes, cell adhesion, spreading, metastasis, and invasion [
6‐
8]. CEACAM5 is a member of the carcinoembryonic antigen and the immunoglobulin superfamily. The CEACAM5 gene, also known as CD66e, codes for the protein, CEA [
9]. CEACAM5 was first described in 1965 as a gastrointestinal oncofetal antigen [
10], but is now known to be overexpressed in a majority of carcinomas, including those of the gastrointestinal tract, the respiratory and genitourinary systems, and breast cancer [
11‐
15]. Studies have demonstrated that OPN is colocalized with the CEACAM1 and enhances invasion of CEACAM1 expressing cells [
16]. At present, no information is available on the expression of CEACAM5 and OPN in squamous carcinoma of tongue. Our study would at evaluating the colocalization of OPN with CEACAM5 and the correlation with the carcinoma of tongue invasion and the degree of differentiation.