Regulation of Autophagy Progress via Lysosomal Depletion by Fluvastatin Nanoparticle Treatment in Breast Cancer Cells

Abstract

Fluvastatin (FLV) is a statin family member that may play a role in modulating a variety of medical disorders such as atherosclerosis and breast cancer. The present study addresses the ability of FLV to modulate the cellular immune response and provides a new nanosized FLV formula (self-nanoemulsifying delivery system, SNED) potentially more effective for suppression of breast cancer development. We monitored autophagic machinery through the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3I/II). Lysosomal activity upon treatment was evaluated by mRNA and protein expression of lysosomal-associated membrane protein 1 (LAMP-1). Mitogen-activated protein kinase (MAPK) signaling and its association with proinflammatory cytokine secretion were assessed in treated cells. Autophagosome formation was significantly increased in cells that were pretreated with FLV-SNED in comparison to FLV-treated cells. Activation of autophagy was accompanied with arrest of LAMP-1 expression, which correlates with lysosomal activity. Simultaneously, both FLV and FLV-SNED activated MAPK signaling and modified interleukin-6 and tumor necrosis factor-α levels in treated cells. These findings indicate that FLV reduces cell viability via depletion of lysosomal activities along with accumulation of autophagosomes leading to disturbance of autophagosome-lysosomal fusion in treated cells. Furthermore, our data reveal the effectiveness of both FLV agents in the modulation of proinflammatory cytokine secretion from treated cells via regulation of MAPK signaling cascades and indicate that FLV-SNED is more efficient than FLV. This study provides new insights into how FLV regulates breast cancer cell viability via modulation of AMPK-mTOR and ERK-mTOR signaling, and through autophagosome formation accompanied by lysosomal degradation.

Emerging Autophagy Functions Shape the Tumor Microenvironment and Play a Role in Cancer Progression - Implications for Cancer Therapy

“…Fluvastatin belongs to the statin family and when used in vitro to treat breast cancer cells, it induced autophagy but with impaired lysosome function which may contribute to cell death. Moreover, a decrease of proinflammatory cytokines, such as IL-6 and TNF-a, was observed along with autophagy consequent effect in tumor immunity (230).…”

Self-Assembly of Amphiphilic Compounds as a Versatile Tool for Construction of Nanoscale Drug Carriers

“…It should be noted that not only the endo-lysosomal system affects the nanoparticle but also vice versa. In recent studies, it was shown that cells treated with nanosized fluvastatin show increasing levels of autophagosome formation that competitively inhibit lysosomal activity [ 184 ]. It was shown that after internalization of nanoparticles functionalized with cell membrane penetrating peptide (TAT peptide), bystander nanoparticles, without any cell-penetrating ligands, can enter into the cells through the same endocytic pathway as functionalized nanoparticles [ 185 ].…”

“…Pegylation of nanocarriers is documented to inhibit endosomal escape, which was testified in the transfection efficacy studies. Therefore, unique approaches were needed to answer this part of the PEG dilemma, including design of pH-responsive PEG-lipids or PEG-PEI conjugates, cleavable pegylated agents bridged by pH-sensitive bonds, e.g., ester, amide, disulfide, that undergo cleavage at low pH with the PEG residue released [ 184 , 193 , 194 ].…”

Effective Targeting of Raf-1 and Its Associated Autophagy by Novel Extracted Peptide for Treating Breast Cancer Cells

“…Importantly, the recruiting of autophagy-related proteins family (Atg5-Atg12/ Atg16) is required for initiating autophagy, whereas the conversion of unlipidated Atg8, the microtubule-associated protein light chain-3B (LC3B), to lipidated LC3B is essential for the elongation and maturation step (16). Raising evidence indicated a direct association of autophagy in maintaining the solid tumors, in which the cells are in urgent need to resist harmful changes during cell division such as lacking nutrients and oxidative stress (hypoxia) (17,18). On the other hand, several studies reported the anticancer activity of the naturally purified glycoproteins such as the short peptides extracted from Achatina fulica mucus in treating breast cancer (19,20).…”