Expression of integrin β1 in squamous cell carcinoma

Objective: To study the expression of integrin β1 in squamous cell carcinoma (SCC) and explore the relationship between stem cell marker and SCC. Methods: The expressions of integrin β1 in SCC tissues and SCC cell strain A431 were detected with immunohistochemical methods and cell staining method. The differentiation of SCC cells were induced with all-trans-retinoic acid (ATRA). The changes of integrin β1 levels before and after induction were detected with RT-PCR. Results: In highly differentiated SCC tissues, integrin β1 was constantly expressed in the basal-like cells in the edge of tumor; some cells inside arranged as island also showed positive integrin β1 expression. In poorly differentiated SCC tissues, island-like integrin β1-positive cells remarkably increased and distributed in a diffuse way. In SCC A431 cells, integrin β1 was expressed unevenly in tumor cells. After treatment by ATRA, level of integrin β1 mRNA in A431 cells significantly decreased compared with untreated control (P < 0.05), and the ratios between the intensity values of integrin β1 to β-actin were 0.071 ± 0.025 and 0.029 ± 0.018 at 24 h and 48 h, respectively, whereas in controls were 0.148 ± 0.027 and 0.136 ± 0.011 (P < 0.05). Conclusions: Integrin β1 is heterogeneously expressed in both SCC tissues and SCC A431 cells. The expression of Integrin β1 decreases when the differentiation level of tumor cells increase, indicating that integrin β1 is closely related with the initiation of SCC and potential cancer stem cells in SCC.