The role of Beclin 1 in SDT-induced apoptosis and autophagy in human leukemia cells.

Abstract

PURPOSE:

To prove the occurrence of autophagy after treatment by protoporphyrin IX (PpIX)-mediated sonodynamic therapy (SDT) of human chronic myelogenous leukemia K562 cells as well as its relationship with apoptosis.

MATERIALS AND METHODS:

The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenylter-trazolium bromide tetrazolium (MTT) assay was adopted to examine cytotoxicity of different treatments. Nuclear morphology changes were observed under a fluorescence microscopy with 4'-6-Diamidino-2-Phenylindole (DAPI) staining. Western blotting was used to analyze the expression of caspase-3, Beclin 1 (BECN 1) and the conversion of LC3- phosphatidylethanolamine conjugate/a cytosolic form of LC3 (LC3 II/I). Fluorescence microscope was used to identify the formation of autophagic vacuoles (AVO) during autophagy.

RESULTS:

Under optimal conditions, SDT was shown to induce autophagy in K562 cells, which caused the up-regulation of Beclin-1 and the formation of AVO. In addition, pre-treatment of cancer cells with Beclin 1-targeted short hairpin RNA (Beclin 1 shRNA) was shown to reduce the level of LC3-II accumulation and staining with punctate spots of monodansylcadaverine (MDC) staining. Besides, the cytotoxic effect of SDT was significantly increased by Beclin 1 shRNA. Furthermore, studies showed a marked effect on the apoptosis of cells by Beclin 1 shRNA to sonodamage with increased DAPI staining and caspase-3 cleavage.

CONCLUSIONS:

These results demonstrated that SDT significantly induced autophagy of K562 cells, probably to protect the K562 cells from sonodamage.

• Authors: Xiaomin Su, Xiaobing Wang, Quanhong Liu, Pan Wang, Chuanshan Xu, Albert Wingnang Leung
• Journal: International journal of radiation biology (Int J Radiat Biol) Vol. 91 Issue 6 Pg. 472-9 (Jun 2015) ISSN: 1362-3095 [Electronic] England
• PMID: 25758178 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Apoptosis Regulatory Proteins
• BECN1 protein, human
• Beclin-1
• Fluorescent Dyes
• Indoles
• Membrane Proteins
• Photosensitizing Agents
• Protoporphyrins
• RNA, Small Interfering
• DAPI
• protoporphyrin IX
• CASP3 protein, human
• Caspase 3

Topics

• Apoptosis (genetics)
• Apoptosis Regulatory Proteins (antagonists & inhibitors, genetics, metabolism)
• Autophagy (genetics)
• Beclin-1
• Caspase 3 (metabolism)
• Fluorescent Dyes
• Gene Knockdown Techniques
• Humans
• Indoles
• K562 Cells
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive (metabolism, pathology, therapy)
• Membrane Proteins (antagonists & inhibitors, genetics, metabolism)
• Photosensitizing Agents (therapeutic use)
• Protoporphyrins (therapeutic use)
• RNA, Small Interfering (genetics)
• Ultrasonic Therapy (methods)
• Vacuoles (pathology)