マウスB16-BL6細胞における酸性細胞外pH誘導性MMP-9発現誘導経路に対するPAK6/7の役割

• Published in: 日本口腔外科学会雑誌 Vol. 70; no. 9; pp. 364 - 371
• Main Authors: 川嶋, 雅之, 加藤, 靖正, 御代田, 駿, 小嶋, 忠之, 前田, 豊信, 高田, 訓
• Format: Journal Article
• Language: Japanese
• Published: 公益社団法人 日本口腔外科学会 20.09.2024
• Subjects: p21アクチベートキナーゼ (PAK); PAK6, PAK5/7; マトリックスメタロプロテアーゼ-9 (MMP-9)
• ISSN: 0021-5163; 2186-1579
• DOI: 10.5794/jjoms.70.364

It is well known that extracellular pH (pHe) tumor tissue is acidic, and sometimes induces matrix metalloproteinase-9 (MMP-9) expression, invasion and metastasis. The small G protein RhoA plays a role in the intracellular signaling pathway for acidic pHe. In this study, PAK6 and PAK7, two of the p21 activated kinases (PAKs) that are known to act downstream of small G proteins, were investigated and their role in acidic pHe signaling inducing MMP-9 expression was examined. PAK6 and PAK7 double knockout cell variants (PAK6/7 KO cells) of mouse B16-BL6 melanoma were prepared via the CRISPR / Cas9 method. MMP-9 activity and mRNA levels were analyzed by gelatin zymography and quantitative PCR, respectively. Enforced expression of PAK6/7 decreased the induction of MMP-9 in parental B16-BL6 cells. On the contrary, the acidic pHe-induced MMP-9 expression level in PAK6/7 KO cells was higher than in parental cells, while MMP-9 induction was absent in PAK6/7 KO cells at neutral pHe. When PAK6/7 KO cells were rescued by introduction of vectors expressing wild type PAK6/7 and its mutants including constitutively active and kinasedead forms, acidic pHe-induced MMP-9 expression was suppressed by the introduction of wild-type and constitutively active PAK6/7, but not by the kinase-dead forms. These results suggest that PAK6/7 play a role of negative feedback in acidic pHe signaling to induce MMP-9 expression.