Mechanism of Anti‐tumor Effect of Combination of Bleomycin and Shock Waves

Abstract

We have previously reported marked enhancement of the cytocidal effect of bleomycin (BLM) on cancer cell suspensions in vitro by the combination with shock waves. In this study, we evaluated the synergistic effects on cancer cell proliferation and apoptosis in solid tumors. A spherical piezoceramic element was used as the shock wave source, with a pressure peak of 40 MPa. A human colon cancer cell line, SW480 was implanted onto the back of nude mice. Two thousand shock waves were administered to the tumor immediately following an intravenous injection of BLM at a dose of one-tenth of the LD 50 . The tumor was extirpated at 3, 6, 12, 24, 72 h and 1 week following shock exposure. Cell proliferation and apoptosis were detected by Ki-67 using antibody MIB-1 and by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method. The lowest percentage (35.7%) of Ki-67-positive cells appeared 24 h following the treatment. The maximum apoptotic index was detected within 6 h following the treatment. Moreover, numerous large cells with enlarged nuclei were detected histologically. These results suggest that shock waves may enhance chemotherapeutic effects by increasing apoptosis and decreasing cell proliferation in the tumor tissue. Key words: Shock wave -Bleomycin -SW480 -TUNEL -Mitotic deathA focused underwater shock wave can exert a high acoustic intensity in deep portions of the body without causing damage to adjacent tissues because of its high permeability through the tissues.1-3) The apparent feasibility of exposing a spatially limited region of the body to a potentially destructive form of mechanical energy has led to the idea of applying shock waves in tumor therapy. 4)Previous results have not necessarily been promising, in cases of shock wave therapy alone, [4][5][6][7][8] or in combination with various anti-cancer agents, for example, cisplatinum, 9-13) mitomycin C (MMC), 12, 13) actinomycin D, 12) methotrexete 13) and adriamycin (ADR). 11, 13, 14) However, we have reported that the combination of focused shock waves and bleomycin (BLM) reduced the IC 50 of BLM to 1/10 000-1/100 000 in various human cancer cell lines, when compared to BLM alone. 15,16) This effect was detected even with a weak shock wave energy, which alone had almost no cytotoxic effect, and the degree of cytotoxicity enhancement was proportional to the amount of shock wave energy applied. 15,16) Immediately after shock wave exposure, cancer cells were examined under scanning and transmission electron microscopes. Numerous dimples (diameters distributed from 0.05 to 0.5 µm) became apparent on the cell surface.15, 16) These dimples were concluded to be pores penetrating through the cell membrane, because reagents such as propidium iodide and 5(6)-carboxyfluorescein could enter the cytoplasm of the cells treated with shock waves. The mechanism of this enhancement of chemotherapeutic effect was considered to be the entry of BLM molecules into cells through pores opened by the shock waves, but the details rem...

High energy shock waves enhance the cytotoxic effect of doxorubicin and methotrexate to human osteosarcoma cell lines

“…The in vitro effects of shock waves are due to a suppression of cell proliferation correlated with an apoptotic cell death process; moreover, HESW treatment has been shown to cause a transient increase in cell membrane permeability by opening micropores (such as electroporation), allowing higher intracellular drug concentration (12-16). This effect has been shown as being capable of increasing the cytotoxicity of various chemotherapeutic agents on different tumour types, allowing treatments with lower doses of drugs in vitro (17)(18)(19), in vivo in animal models (12,20) and in one patient with prostate cancer (21).…”

“…The in vitro effects of shock waves are due to a suppression of cell proliferation correlated with an apoptotic cell death process; moreover, HESW treatment has been shown to cause a transient increase in cell membrane permeability by opening micropores (such as electroporation), allowing higher intracellular drug concentration (12-16). This effect has been shown as being capable of increasing the cytotoxicity of various chemotherapeutic agents on different tumour types, allowing treatments with lower doses of drugs in vitro (17)(18)(19), in vivo in animal models (12,20) and in one patient with prostate cancer (21).This evidence led us to study the effects of HESW on OS cell lines and how to enhance cytotoxicity with a combined therapy with HESW and doxorubicin (DOXO) or methotrexate (MTX). These cytotoxic agents have been chosen since their well-known activity against OS and their routine use in clinical protocols for the treatment of OS patients (22)(23)(24)(25)(26)(27).…”

Investigation of shock wave focusing in water in a logarithmic spiral duct, Part 1: Weak coupling

“…In recent years, the use of shock wave focusing in biomedical applications has increased. Examples are shock wave lithotripsy (Mulley, 1986;Gerald, 1997;Weiland et al, 2007) and drug delivery by shock waves (Kato et al, 2000;Doukas and Kollias, 2004). The working medium for both of these applications is water or a water solution.…”

Sperm whales ability to avoid approaching vessels is affected by sound reception in stratified waters

“…For example, a planar shock front becomes curved as it propagates inside a shock wave lithotripter, a reflector in a particular shape used to generate a focused shock wave to destroy kidney stones (Mulley, 1986). Examples are shock wave lithotripsy (Mulley, 1986;Gerald, 1997;Weiland et al, 2007) and drug delivery by shock waves (Kato et al, 2000;Doukas and Kollias, 2004). Most of the work focused on the generation and stability of cylindrical and spherical converging shock waves in gases (Guderley, 1942;Perry and Kantrowitz, 1951;Takayama et al, 1987;Schwendeman and Whitham, 1987;Eliasson et al, 2008).…”