Growth inhibition of high-intensity focused ultrasound on hepatic cancer in vivo.

AIM: To investigate the damaging effect of high-intensity focused ultrasound (HIFU) on cancer cells and the inhibitory effect on tumor growth. METHODS: Murine H22 hepatic cancer cells were treated with HIFU at the same intensity for different lengths of time and at different intensities for the same length of time in vitro, the dead cancer cells were determined by trypan blue staining. Two groups of cancer cells treated with HIFU at the lowest and highest intensity were inoculated into mice. Tumor masses were removed and weighed after 2 wk, tumor growth in each group was confirmed pathologically. RESULTS: The death rate of cancer cells treated with HIFU at 1 000 W/cm2 for 0.5, 1, 2, 4, 8, and 12 s was 3.11+/-1.21%, 13.37+/-2.56%, 38.84+/-3.68%, 47.22+/-5.76%, 87.55+/-7.32%, and 94.33+/-8.11%, respectively. A positive relationship between the death rates of cancer cells and the length of HIFU treatment time was found (r = 0.96, P<0.01). The death rate of cancer cells treated with HIFU at the intensity of 100, 200, 400, 600, 800, and 1 000 W/cm2 for 8 s was 26.31+/-3.26%, 31.00+/-3.87%, 41.97+/-5.86%, 72.23+/-8.12%, 94.90+/-8.67%, and 99.30+/-9.18%, respectively. A positive relationship between the death rates of cancer cells and the intensities of HIFU treatment was confirmed (r = 0.98, P<0.01). The cancer cells treated with HIFU at 1 000 W/cm2 for 8 s were inoculated into mice ex vivo. The tumor inhibitory rate was 90.35% compared to the control (P<0.01). In the experimental group inoculated with the cancer cells treated with HIFU at 1 000 W/cm2 for 0.5 s, the tumor inhibitory rate was 22.9% (P<0.01). By pathological examination, tumor growth was confirmed in 8 out of 14 mice (57.14%, 8/14) inoculated with the cancer cells treated with HIFU at 1 000 W/cm2 for 8 s, which was significantly lower than that in the control (100%, 15/15, P<0.05). CONCLUSION: HIFU is effective on killing or damage of H22 hepatic cancer cells in vitro and on inhibiting tumor growth in mice ex vivo.

[A study of the inhibition effect of HIFU and its mechanism of action on the proliferation of human breast cancer cells].

OBJECTIVE: To investigate the killing effect of high intensity focused ultrasound (HIFU) on human tumor cells and study the mechanism of its action. METHODS: Human breast cancer cells MCF-7 were treated with different intensity of HIFU in vitro and incubated. The killing effect and proliferation inhibition effect of HIFU on tumor cells were investigated with the methods of trypan blue exclusion assay, MTT assay and colony formation assay. And the cell cycle, apoptotic cells and the expressions of P53, BCL-2, FAS and HSP70 were measured with flow cytometry. RESULTS: After HIFU treatment, the death rates of cancer cell increased, the proliferation of cell waned (P < 0.05), the number of colony formation decreased (P < 0.001), the cell number increased in G0/G1 phase (P < 0.05) and decreased in S phase, the apoptotic indices increased (P < 0.01), the expression of HSP70 was enhanced, and no significant changes of P53, BCL-2, FAS expressions were found (P > 0.05). CONCLUSION: HIFU produces significant effects such as killing, proliferation inhibition and colony formation inhibition on human breast cancer cells; its mechanism of action may be associated with the inhibition of DNA synthesis. In addition, HIFU treatment can induce apoptotic cell death, which may not be associated with the mediation and regulation of P53, BCL-2 and FAS genes.