Antitumor and anti-invasive effects of diverse musk-fragrant macrocyclic ketones and their enhancement by hyperthermia

The antitumor and anti-invasive activities of the low-molecular-weight macrocyclic ketones (MCKs), such as musk secreted from the mammalian genital glands and musk released from relatively unkown plants, were investigated comparatively together with the enhancement of the effects in combination with hyperthermia. Ehrlich ascites tumor cells were treated with each MCK and cultured, followed by evaluation of the cell viability using the mitochondrial dehydrogenase-based WST-8 assay. The number of HT-1080 human fibrosarcoma cells cultured with the MCKs or invading through a reconstituted basement membrane was measured using microscopy. The order of the efficiency was as follows: (Z)-g-cycloheptadecen-1-one (Hp) (17:1, musk rats), 8-cyclohexadecen-1-one (16:1, musk ferns), cyclopentadecanone (15:0, musk rats) and 3-methylcyclopentadecanone (16:0, musk deer), having 15-17 carbon atoms with and without a double bond, which exhibited a carcinostatic effect either at 100 µM for 20-h culture or at 50 µM for 72-h culture. The effects were markedly enhanced by heat treatment at 42˚C. MCKs were not found in the cells by gas-liquid chromatographic determination, indicating that the carcinostatic effects were attributed to their surface activity on the cell membrane. Invasion of HT-1080 cells was inhibited by MCKs at doses scarcely diminishing the cell viability, indicating that the suppression of invasiveness did not ensue from the secondary action due to carcinostasis. The order of invasion-inhibitory efficacy of the MCKs was, however, similar to that of their carcinostatic effects. Hp17:1 also exhibited the highest anti-invasive activity in addition to the highest carcinostatic activity. The two inhibitory effects were promoted by combination with hyperthermia. MCKs with a double bond, particularly Hp17:1 rather than 8-Hx16:1, but not saturated-aliphatic MCKs, may be potent multi-applicable antitumor agents due to their dual inhibitory activities against tumor progression and invasion and in hyperthermia‑combined therapy.