Dimethyl Sulfoxide Suppresses Mouse 4T1 Breast Cancer Growth by Modulating Tumor-Associated Macrophage Differentiation / 한국유방암학회지

PURPOSE: The universal organic solvent dimethyl sulfoxide (DMSO) can be used as a differentiation inducer of many cancer cells and has been widely used as a solvent in laboratories. However, its effects on breast cancer cells are not well understood. The aim of this study is to investigate the effect and associated mechanisms of DMSO on mouse breast cancer. METHODS: We applied DMSO to observe the effect on tumors in a mouse breast cancer model. Tumor-associated macrophages (TAMs) were tested by flow cytometry. Ex vivo tumor microenvironment was imitated by 4T1 cultured cell conditioned medium. Enzyme-linked immunosorbent assays were performed to detect interleukin (IL)-10 and IL-12 expression in medium. To investigate the cytotoxicity of DMSO on TAMs, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were performed. RESULTS: We found that DMSO produced tumor retardation when injected into mouse peritoneal cavities in a certain concentration range (0.5-1.0 mg/g). Furthermore, as detected by flow cytometry, TAM subtypes were found to be transformed. We further imitated a tumor microenvironment in vitro by using 4T1 cultured cell conditioned medium. Similarly, by using low concentration DMSO (1.0%-2.0% v/v), TAMs were induced to polarize to the classically activated macrophage (M1-type) and inhibited from polarizing into the alternatively activated macrophage (M2-type) in the conditioned medium. IL-10 expression in tumors was reduced, while IL-12 was increased compared with the control. Furthermore, we reported that 2.0% (v/v) DMSO could lead to cytotoxicity in peritoneal macrophages after 48 hours in MTT assays. CONCLUSION: Our findings suggest that DMSO could exert antitumor effects in 4T1 cancer-bearing mice by reversing TAM orientation and polarization from M2- to M1-type TAMs. These data may provide novel insight into studying breast cancer immunotherapy.

Autophagy activators rescue and alleviate pathogenesis of a mouse model with proteinopathies of the TAR DNA-binding protein 43.

TDP-43 is a multifunctional DNA/RNA-binding protein that has been identified as the major component of the cytoplasmic ubiquitin (+) inclusions (UBIs) in diseased cells of frontotemporal lobar dementia (FTLD-U) and amyotrophic lateral sclerosis (ALS). Unfortunately, effective drugs for these neurodegenerative diseases are yet to be developed. We have tested the therapeutic potential of rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR) and three other autophagy activators (spermidine, carbamazepine, and tamoxifen) in a FTLD-U mouse model with TDP-43 proteinopathies. Rapamycin treatment has been reported to be beneficial in some animal models of neurodegenerative diseases but not others. Furthermore, the effects of rapamycin treatment in FTLD-U have not been investigated. We show that rapamycin treatment effectively rescues the learning/memory impairment of these mice at 3 mo of age, and it significantly slows down the age-dependent loss of their motor function. These behavioral improvements upon rapamycin treatment are accompanied by a decreased level of caspase-3 and a reduction of neuron loss in the forebrain of FTLD-U mice. Furthermore, the number of cells with cytosolic TDP-43 (+) inclusions and the amounts of full-length TDP-43 as well as its cleavage products (35 kDa and 25 kDa) in the urea-soluble fraction of the cellular extract are significantly decreased upon rapamycin treatment. These changes in TDP-43 metabolism are accompanied by rapamycin-induced decreases in mTOR-regulated phospho-p70 S6 kinase (P-p70) and the p62 protein, as well as increases in the autophagic marker LC3. Finally, rapamycin as well as spermidine, carbamazepine, and tamoxifen could also rescue the motor dysfunction of 7-mo-old FTLD-U mice. These data suggest that autophagy activation is a potentially useful route for the therapy of neurodegenerative diseases with TDP-43 proteinopathies.

Mechanism mediating oligomeric Aß clearance by naïve primary microglia.

The accumulation of soluble oligomeric amyloid-ß peptide (oAß) proceeds the formation of senile plaques and contributes to synaptic and memory deficits in Alzheimer's disease (AD). The mechanism of mediating microglial oAß clearance remains unclear and thought to occur via scavenger receptors (SRs) in microglia. SRs respond to their ligands in a subtype-specific manner. Therefore, we sought to identify the specific subtypes of SRs that mediate oAß internalization and proteases that degrade oAß species in naïve primary microglia. The component of oAß species were characterized by western blot analysis, analytical ultracentrifugation analysis, and atomic force microscopy. The oAß species remained soluble in the medium and microglial lysates during incubation at 37 °C. SR-A, but not CD36, mediated oAß internalization in microglia as suggested by the use of subtype-specific neutralizing antibodies and small interfering RNAs (siRNAs). Immunoprecipitation analysis showed that oAß interacted with SR-A on the plasma membrane. After internalization, over 40% of oAß vesicles were trafficked toward lysosomes and degraded by cysteine proteases, including cathepsin B. The inhibitors of proteasome, neprilysin, matrix metalloproteinases, and insulin degrading enzyme failed to protect internalized oAß from degradation. Our study suggests that SR-A and lysosomal cathepsin B are critical in microglial oAß clearance, providing insight into how microglia are involved in the clearance of oAß and their roles in the early stages of AD.