口腔癌細胞のシスプラチン耐性化に伴うNa, K-ATPase及びouabain感受性の変化

Na, K-ATPase

北海道歯学会

北海道歯学雑誌

Purpose : Resistance of cancer cells is an obstacle in chemotherapy for cancer by cisplatin (CDDP). But it is not well elucidated in the mechanism. We examined the change of Na, K-ATPase accompanied by the acquisition of the CDDP resistance of oral cancer cells. Methods : Oral cancer cell lines (Sa3, H1, KB) and CDDP-resistant lines of (Sa3R, H1R, KBR) provided from Chiba University, Faculty of Medicine and cells collected from normal gingiva, were used. Na, K-ATPase activity and cell viability under treatment ouabain and CDDP for each cell was measured. Assessment of Na, K-ATPase α subunits, ATP7A and P-glycoprotein (P-gp) was done by western blotting. Results : According to CDDP, 50% inhibitory concentration (IC50) was, 7.5 × 10-4 M and 1.5 × 10-4 M respectively in H1R and H1, 6.0×10-3 M and 4.5×10-3 M respectively in Sa3R and Sa3, 7.0×10-4 M and 1.0×10-4 M respectively in KBR and KB. CDDP sensitivity was lower than the normal gingival cells to cancer cells. Resistant strains showed a lower sensitivity than the more sensitive strains of each. 　Measurement of Na, K-ATPase activity, Sa3R is higher than Sa3, H1R was higher than H1 slightly, but there was no significant difference in the KBR and KB. Activity measurements were consistent in Na, K-ATPase and protein expression levels. IC50 was examined for each cell in the presence of ouabain and were 80 nM and 60 nM in the H1R and H1, 180 nM and 80 nM in the Sa3R and Sa3, 130 nM and 40 nM in the KBR and KB. The normal gingival cells was 5 nM. 　From the results of these examinations, it was suggested the cancer cells resistant to CDDP get resistant to ouabain at the same time. As for the ouabain concentration dependence of Na, K-ATPase inhibition of the cells, there is no significant difference in the 50% inhibitory concentration between resistant and parent lines. Therefore, change of Na,KATPase sensitivity to ouabain was not related to resistance of the cells against ouabain. It was suggested that P-gp and Na, K-ATPase, ATP7A is involved in CDDP resistance. The mechanism depends on the type of cells, although we found no features that are common in the between the parent and resistant lines for the expression of ATP7A and P-gp.