Epidermal growth factor messenger RNA production in human lacrimal gland

Experimental models and clinical investigations have suggested that epidermal growth factor (EGF) may have a role in corneal wound healing. It has been identified as a normal component of human tears. Rabbit and mouse lacrimal glands have recently been shown to synthesize EGF messenger RNA (mRNA). The purpose of the present study was to determine whether the human lacrimal gland synthesizes EGF mRNA. Total cellular RNA was isolated from pathologic specimens of normal human lacrimal glands from two individuals. Reverse transcriptase was used to generate complementary DNA (cDNA) using a human EGF-specific mRNA primer. Amplification of EGF-related cDNA sequences was performed with the polymerase chain reaction (PCR) and human EGF-derived up- and downstream primers. The PCR products from both lacrimal glands contained an amplified product of the expected length of approximately 410 base pairs. The PCR-generated fragment was verified as an EGF-related amplification product with Southern blotting using a synthetic oligonucleotide probe derived from the mature coding sequence of EGF. These results conclusively demonstrate that the human lacrimal gland synthesizes EGF and suggest that the lacrimal gland could have a regulatory role in maintaining the ocular surface and possibly regulating corneal wound healing through the secretion of EGF.