Effects of the microbubbles combined with different mechanical index ultrasound irradiation on ultrastructure and migration of colon cancer cells

Abstract

Objective To investigate the effects of the microbubbles combined with different mechanical index ultrasound irradiation on ultrastructure and migration of colon cancer cells. Methods The experimental study was conducted. Colon cancer cells in vitro (Lovo cells) were cultured and divided into 4 groups, cells in the A group were not treated and cells in the B, C and D groups were treated by microbubbles combined with different mechanical index ultrasound irradiation (mechanical index were 0.20, 0.80 and 1.45). The changes of ultrastructure and migration of cells were observed using laser scanning confocal microscope and Millicell-PCF cell culture chamber method, respectively. Measurement data with normal distribution were represented as ±s. Comparisons among groups were analyzed by the one-way ANOVA. Pairwise comparisons were done by the t test. Results (1) Effects of the microbubbles combined with different mechanical index ultrasound irradiation on ultrastructure of Lovo cells: Lovo cells in the A group showed big nucleus, less plasma, regular arrangement, jagged-like or more irregular varicosity surrounding nucleus, twisted euchromatin, expansion of nucleus cisternal space, homogeneous distribution and normal development of granular soil and clear mitochondrial ridge-like structures. Lovo cells in the B group showed big nucleus with regular arrangement, obvious nucleolus margination, endoplasmic reticulum dilatation, normal development of mitochondrion and clear mitochondrial ridge-like structures. Lovo cells in the C group showed broadening nucleus space, abnormal nucleus with karyopycnosis, chromatin condensation, a few remaining or obvious dilatation of rough endoplasmic reticulum, typically consisting of different fragments or bubbles, cytoplasmic vacuoles changes and decreasing mitochondrial ridge-like structures. Lovo cells in the D group showed big and irregular nucleus, nucleolus margination, obvious endoplasmic reticulum dilatation, fewer mitochondrion with extended cell area and swelling shape, rare mitochondrial ridge-like structures with disordered or broken arrangement, even disappearing. (2) Effects of the microbubbles combined with different mechanical index ultrasound irradiation on migration of Lovo cells: Millicell-PCF cell culture chamber method showed that number of migration of Lovo cells were respectively 63±7, 61±4, 21±3 and 19±5 in the A, B, C and D groups, with a statistically significant difference (F=55.040, P 0.05) and between group C and D (t=2.013, P>0.05). There were statistically significant differences in migration of Lovo cells between group A and C or D (t=7.861, 10.652, P<0.05) and between group B and group C or D (t=7.161, 10.453, P<0.05). Conclusion Microbubbles combined with high mechanical index ultrasound irradiation can make the ultrastructural alterations in the cancer cells, resulting in tumor cell degeneration and death, ultimately inhibit tumor cell migration and metastasis. Key words: Colonic neoplasms; Ultrastructures; Migration; Ultrasonography