Synergistic Effect of Doxorubicin and Blue Light Irradiation on the Antitumor Treatment of HepG2 Cells in Liver Cancer

Doxorubicin (DOX) has been an effective antitumor agent for human liver cancer cells; however, an overdose might lead to major side effects appearing in clinical applications. In this work, we present a strategy of combining DOX and blue light (BL) irradiation for the antitumor treatment of HepG2 cells (one typical human liver cancer cell line). It is demonstrated that synergetic DOX and BL can significantly reduce cell proliferation and increase the apoptotic rate of HepG2 cells in comparison to individual DOX treatment. The additional BL irradiation is further helpful for enhancing the inhibition of cell migration and invasion. Analyses of reactive oxygen species (ROS) level and Western blotting reveal that the strategy results in more ROS accumulation, mitochondrial damage, and the upregulation of proapoptotic protein (Bcl-2) and downregulation of antiapoptotic protein (Bax). In addition to the improved therapeutic effect, the non-contact BL irradiation is greatly helpful for reducing the dosage of DOX, and subsequently reduces the side effects caused by the DOX drug. These findings offer a novel perspective for the therapeutic approach toward liver cancer with high efficiency and reduced side effects.

Proliferation inhibition and apoptosis of liver cancer cells treated by blue light irradiation

Blue light (BL) irradiation has been a potentially efficient treatment for many kinds of tumors. In this study, a BL irradiation (centered at 453 nm in wavelength) was proposed to treat the common human liver cancer cell lines of SMMC-7721 and HepG2, examined by means of flow cytometry, western blot, fluorescence microscope assay. In comparison to control groups, the apoptosis and proliferation inhibition of both BL-treated cells are expressively enhanced by mitochondrial apoptosis. The mechanism of apoptosis is related to the more production of reactive oxygen species (ROS) induced by BL and the corresponding changes in the expression of apoptosis-related Bcl-2, Bax and Bad proteins. In addition, the migration rate of the cancer cells could be reduced after BL irradiation. These results demonstrate that introducing BL irradiation is helpful to establish an effective and low toxicity strategy for the clinical treatment of liver tumors.

Blue light induces ROS mediated apoptosis and degradation of AML1-ETO oncoprotein in Kasumi-1 cells

Light-emitting diode (LED)-based therapies, particularly blue LEDs with wavelengths of 400-500 nm, have shown beneficial results in several cancers, including melanoma, lymphoid cells, and skin tumors. In this study, the cell viability and apoptosis of Kasumi-1 cells treated by blue light (BL) irradiation have been explored. Firstly, BL can specially inhibit the proliferation and promote the apoptosis of Kasumi-1 cells. Furthermore, the apoptosis was triggered by the production of reactive oxygen species and the decline of mitochondrial membrane potential which was regulated by the ratio of Bcl-2(Bcl-xL)/Bax; BL caused the cells' final apoptosis accompanied with the increased cleavage of caspase-3 and poly-ADP-ribose polymerase. Finally, BL induced the degradation of AML1-ETO dependent on the activation of caspase-3. These results are helpful for establishing a low toxicity and high efficiency strategy of BL irradiation for clinical treatment of Kasumi-1 cells.

Inhibition of Proliferation in U937 Cells Treated by Blue Light Irradiation and Combined Blue Light Irradiation/Drug

The cell viability and apoptosis of tumor U937 cells treated by blue light (BL) irradiation have been examined. BL irradiation can specially inhibit the proliferation and promote the apoptosis of U937 cells, relating to the production of reactive oxygen species (ROS) and the decline of mitochondrial membrane potential (ΔΨm). The apoptosis is further associated with varying downregulated B-cell lymphoma-extra large (Bcl-X_L) and B-cell lymphoma 2 (Bcl-2) genes, upregulated Bcl-2-associated X (Bax) gene, the activation of caspase-3 and caspase-9, and the cleavage of poly (ADP-ribose) polymerase (PARP) by the BL irradiation process. Moreover, BL irradiation induced proliferation inhibition is higher than that treated by a common chemotherapeutic drug of homoharringtonine (HHT). When we synergize BL irradiation with HHT (BL-HHT), a higher proliferation inhibition is obtained than that treated by BL irradiation or HHT alone. These results are helpful for establishing a low toxicity and high efficiency strategy of BL irradiation for clinical treatment of acute myeloid leukemia, not limited to U937 cells.

Blue light-induced apoptosis of human promyelocytic leukemia cells via the mitochondrial-mediated signaling pathway

Acute promyelocytic leukemia is frequently associated with dizziness, fever, nausea, hematochezia and anemia. Blue light, or light with wavelengths of 400–480 nm, transmits high levels of energy. The aim of the present study was to determine the pro-apoptotic effects of blue light (wavelength, 456 nm; radiation power, 0.25 mW/cm²) and the underlying mechanisms in a human promyelocytic leukemia cell line (HL60). Blue light reduced the viability and enhanced the mortality of HL60 cells in a time-dependent manner. Exposure to blue light for 24 h caused depolarization of the mitochondrial membrane potential and the overproduction of reactive oxygen species in HL60 cells. In a nude mouse model, 9-day exposure to blue light markedly suppressed the growth of HL60-xenografted tumors; however, it had no effect on hepatic and renal tissues. In addition, blue light abrogated the expression of B-cell lymphoma (Bcl)-2 and Bcl extra-long, while enhancing the levels of Bcl-2-associated X protein, cytochrome c, and cleaved caspases-3 and −9 in tumor tissues. The results suggested that the pro-apoptotic effects of blue light in human promyelocytic leukemia cells may be associated with the mitochondrial apoptosis signaling pathway.