Introduction

Canine oral melanoma (cOM) is the most oral malignancy in dogs because of the metastatic behavior of cancer cells. According to the TNM staging system, stage III criteria include a tumor more than 4 cm in diameter or involvement of regional lymph node metastasis. Cell adhesion molecules, including E-cadherin, play pivotal roles in cancer invasion and metastasis. Loss of E-cadherin function was described in migrating cancer cells due to the suppression of cell-cell-adhesion in the epithelial-mesenchymal transition (EMT) process and loss of antigrowth signals.

Objective

To investigate E-cadherin expression in cOM by immunohistochemistry (IHC).

Methods

E-cadherin expression in stage III melanotic and amelanotic cOM (n = 7) and normal canine gingival tissues (n = 7) was evaluated by IHC. The anti-E-cadherin antibody (mouse monoclonal, clone 36, BD Biosciences) at dilution of 1:100 was used. The average percentage of positive staining areas was compared between cOM and normal tissues. Statistical difference was performed by Mann-Whitney test.

Results

The IHC results showed that E-cadherin expression significantly decreased in cOM (16.44% ± 8.051) compared to normal tissues (61.24% ± 8.994) (p < 0.01) (Figure 1).

Figure 1 Immunohistochemical staining for E-cadherin in normal gingiva (A) and cOM (B) (scale bars = 20 µm).

Conclusion

In summary, these results suggested that loss of E-cadherin has been associated with cOM progression by providing cancer cells to activate invasion and metastasis.

Acknowledgement

Ratchadaphiseksomphot Endowment Fund (grant number R_017_2556), Chulalongkorn University graduate scholarship to commemorate the 72nd anniversary of His Majesty King Bhumibol Adulyadej and Doctoral Degree Chulalongkorn University 100th year birthday anniversary scholarship.