EFFECTS OF LIMONENE,SALVIA MILTIORRHIZA AND TURMERIC DERIVATIVES ON H-RAS ONCOGENE EXPRESSION AND GAP JUNCTION INTERCELLULAR COMMUNICATION IN HUMAN SOLID TUMOR CELL LINES

Ｏｎｃｏｇｅｎｉｃｒａｓｐｒｏｔｅｉｎｓａｒｅｃａｕｓａｌｙｉｍｐｌｉｃａｔｅｄｃｅｒｔａｉｎｈｕｍａｎｍａｌｉｇｎａｎｃｉｅｓｗｉｔｈａｂｏｕｔ３０－４０％ｏｆｈｕｍａｎｌｕｎｇａｄｅｎｏｃａｒｃｉｎｏｍａｓ，５０％ｈｕｍａｎｃｏｌｏｎｃａｒｃｉｎ...

Effects of limonene, salvia miltiorrhiza and turmeric derivatives on H-ras oncogene expression and gap junction intercellular communication in human solid tumor cell lines

Objective: To study gap junction intercellular communication (GJIC), H-ras oncogene expression and ras oncogene product (P²¹ ras protein) expression in four human solid tumor cell lines, W1-38, CACO₂, A549 and PaCa, and the effects of four compounds, Salvia miltiorrhiza derivative (SMD), d-Limonene, Turmeric derivative I (TD-I) and Turmeric derivative II (TD-II), on them. Methods: The abilities of the four solid tumor cell lines to transfer dye to adjacent cells were examined by the scrape-loading/dye transfer technique, and the H-ras oncogene expression by Northern blotting and P²¹ ras protein expression by Western blotting. Results: The results showed the loss of intercellular coupling in PaCa cells, slight GJIC in A549 and CACO₂ cells, and a good GJIC in W1-38 cells. The four compounds could improve the GJIC of PaCa to different extents. The amount of total and membrane associated P²¹ ras in PaCa cells were decreased after treatment with SMD, d-Limonene and TD-I (2.5 μg/ml) for 48 h. Concomitantly, the growth of PaCa cells decreased in soft agar and had enhanced GJIC. The relative potency was found to be:d-Limonene>SMD >TD-I=TD-II. There was no significant effect of the four compounds on H-ras oncogene expression. Conclusion: It was suggested that there was an excellent correlation between loss of Lucifer Yellow dye transfer and ras gene mutation rate in the four solid tumor cell lines (ras gene mutation rate inversely correlated with average cell number coupled, r=0.98) i.e., the high ras gene mutation was closely correlated with loss of GJIC in these malignant human tumor cells; The antitumor effect of the monoterpene d-Limonene and the phenol compound, SMD, might be related to inhibition of P²¹ ras membrane association and enhancement of GJIC, whilst that of the others may be by a different mechanism; The inhibition of P²¹ ras membrane association was directly related to the enhancement of gap junction intercellular communication.