Abstract

Introduction: Oesophageal squamous cell carcinoma (ESCC) is an aggressive type of oesophageal cancer in Asia, with a high mortality rate due to the occurrence of chemoresistance. Upregulation of the endopeptidases matrix metalloproteinase (MMP)-9 and MMP-2 are known to contribute to chemoresistance. MMP-9 and MMP-2 overexpression was observed in ESCC. However, their roles in ESCC chemosensitivity are still elusive. This study evaluated the effect of MMP-9/MMP-2 inhibition on the chemosensitivity of ESCC cells towards cisplatin (CDDP) and 5-fluorouracil (5-FU) using co-treatment and pre-treatment models. Methods: ESCC cell line (EC109) was treated with different concentrations of CDDP, 5-FU or MMP-9/MMP-2 inhibitor (MMP-9/MMP-2i) to identify their half-maximal inhibitory concentration (IC₅₀) using MTT assay. Using the IC₅₀ of MMP-9/MMP-2i, co-treatment was conducted with the same concentration range of CDDP and 5-FU for 3, 6 and 24h. In pre-treatment model, MMP-9/MMP-2i (IC₅₀) was added to the cells for 3 or 6 h before treating with the same concentration range of CDDP and 5-FU. Results: Inhibition of MMP-9/MMP-2 activity enhanced EC109 chemosensitivity towards CDDP and 5-FU, except for CDDP in co-treatment model. In the co-treatment model (24h), MMP-9/MMP-2i decreased the IC₅₀ of 5-FU from 1000 μM to 400 μM, while the IC₅₀ of CDDP increased from 40 μM to >80 μM. In the pre-treatment model, the IC₅₀ of CDDP was also reduced from 40 μM to 20 μM at 3 h pre-incubation and from 40 μM to 5 μM at 6 h pre-incubation. Meanwhile, IC₅₀ of 5-FU remained at 1000 μM at 3 h pre-incubation but was reduced to 50 μM at 6 h pre-incubation. Conclusion: The inhibition of MMP-9/MMP-2 activity induces EC109 chemosensitivity towards CDDP and 5-FU in the pre-treatment and co-treatment models. These preliminary results indicate the potential use of MMP-9/MMP-2i to induce ESCC chemosensitivity and deserve further identification of the associated molecular mechanisms.

Keywords: Oesophageal squamous cell carcinoma, Matrix metalloproteinase, Chemoresistance, Chemosensitivity