Antimetastatic Therapies of the Polysulfide Diallyl Trisulfide against Triple-Negative Breast Cancer (TNBC) via Suppressing MMP2/9 by Blocking NF-κB and ERK/MAPK Signaling Pathways

Abstract

Background: Migration and invasion are two crucial steps of tumor metastasis. Blockage of these steps may be an effective strategy to reduce the risk. The objective of the present study was to investigate the effects of diallyl trisulfide (DATS), a natural organosulfuric compound with most sulfur atoms found in garlic, on migration and invasion in triple negative breast cancer (TNBC) cells. Molecular mechanisms underlying the anticancer effects of DATS were further investigated.

Methods and results: MDA-MB-231 cells and HS 578t breast cancer cells were treated with different concentrations of DATS. DATS obviously suppressed the migration and invasion of two cell lines and changed the morphological. Moreover, DATS inhibited the mRNA/protein/ enzymes activities of MMP2/9 via attenuating the NF-κB pathway. DATS also inhibited ERK/MAPK rather than p38 and JNK.

Conclusion: DATS inhibits MMP2/9 activity and the metastasis of TNBC cells, and emerges as a potential anti-cancer agent. The inhibitory effects are associated with down-regulation of the transcriptional activities of NF-κB and ERK/MAPK signaling pathways.

Fig 1. Chemical structure of garlic OSCs.

(A) The plant of garlic. (B) The process of OSCs produced. (C) Chemical structure of DAS/DADS/DATS.

Fig 2. Garlic OSCs inhibited cell viability and changed cell morphology.

An in vitro study was initiated by treating MDA-MB-231 (A) and HS 578T (B) cells with increasing doses of DAS/DADS/DATS (0, 2.5, 5, 10, 20, 40, 80, 160 μM)and DMSO(0.5%) for 24 h. The viability of the OSCs-treated cells was measured using the MTT assay. Results were expressed as a percentage of control, which was considered as 100%. Data were reported as mean ± SD and at least three separate experiments were performed. Cellular morphological changes in MDA-MB-231 (C) and HS 578T (D) cell lines were found in a dose-dependent manner after treated with DATS for 24 h when observed by a Carl Zeiss axio A1, at ×100 magnification. MDA-MB-231(E) and HS578T (F)no-treated or DATS-treated cells were immunostained with Actin-Tracker Greento observe F-actin stress fibers.

Fig 3. DATS inhibited migration in MDA-MB-231 and HS 578T cell lines.

Confluent MDA-MB-231 (A) and HS 578T (B) cells were scratched and incubated at different concentrations of DATS (μM) and DMSO(0.1%). The area covered by migrating cells was recorded by phase-contrast microscopy connected to a digital camera at time 0 and 24 h. The wound closure area was calculated by measuring the diminution of the wound bed surface upon time using Image J software (C) and (D) Representative pictures of three independent experiments were shown. *, indicates P<0.05 versus no DATS group. MDA-MB-23 and HS 578T cells cultured in the upper well, DATS of indicated concentrations were put in the upper wells and add 10% FBS medium in lower wells, migration of the cells were determined by measuring the ability to pass through the filters. Migrated cells under the membrane after 12 hours on invert microscope (×200); The number of migration MDA-MB-231(E) and HS 578T(F)cells;each done in triplicate. *, P < 0.05and **, P < 0.01, compared with the control.

Fig 4. DATS inhibited invasion in a dose-dependent manner in MDA-MB-231 and HS578T cell lines.

Approximately 1×10⁶ cells were seeded in the 24-well plate with cell culture inserts, the cells were treated with different concentrations of DATS (μM) and DMSO(0.1%) for 24 h to test invasion. Assays were performed as described in Materials and Methods. The results showed that DATS inhibited significantly cell invasion in a dose-dependent manner. *, indicates P<0.05 versus no DATS group. Data were shown as means ± SD from three independent experiments.

Fig 5. DATS inhibited the dissemination and metastasis of human tumor cells in zebrafish embryos.

(A) DiI-labeled MDA-MB-231 cell were implanted in the perivitelline space and tumor cell dissemination were examined at day 6 post-injection. Arrows indicate primary tumors. White arrowheads indicate disseminated tumor foci. (B) Quantification of numbers of disseminated tumor foci (n = 10/group); (C) Averages of maximal distances of metastatic foci (n = 10/group).

Fig 6. Critical role of NF-κB in DATS-induced transcriptional inhibition of MMP-2/9.

MDA-MB-231 cells were treated with DATS (0, 2.5, 5, 10, 20 μM) DMSO (0.1%) and for 24 h and then subjected to (A) western blotting to analyze the protein levels of MMP-2/9; (B) Reverse Transcription-PCR and (C) quantitative real-time PCR to analyze the mRNA expression of MMP-2/9; (D) InnoZyme Gelatinase (MMP-2/MMP-9) Activity Assay to analyze the activity of MMP-2/9. (E) NF-κB promoter reporter assay to analyze the promoter activity of NF-κB. (F-H) Representative results of NF-KB protein levels and phosphorylation of IκBα by Western blot analysis.

Fig 7. Effects of DATS on the MAPKs pathway.

MDA-MB-231 cells were cultured in various concentrations of DATS (0, 2.5, 5, 10, 20 μM) for 24 h, and then the cell lysates were subjected to western blots with (A) anti-ERK1/2, anti-JNK, anti-p38 and (total and phosphorylated proteins) antibodies. (B) MDA-MB-231 cells were cultured in 10 μM DATS for different time periods (0–24 h), and then the cell lysates were subjected to western blots with anti-ERK1/2, anti-JNK, anti-p38 and (total and phosphorylated proteins) antibodies. (C) MDA-MB-231 cells were treated with 5 μM U0126 and incubated in the presence or absence of 10 μM DATS for 24 h, and then the cell lysates were subjected to western blots with anti-MMP-2/9, anti-ERK1/2 (total and phosphorylated proteins) antibodies. (D–G) MDA-MB-231 cells were treated with 5 μM U0126 for and incubated in the presence or absence of 10 μM for 24 h, MDA-MB-231 cells were then subjected to cell migration and invasion assay. The migration and invasion abilities of MDA-MB-231 cells were quantified by counting the number of cells that invaded to the underside of the porous polycarbonate. The values represented the means ± SD of at least three independent experiments.*P<0.05 as compared with the vehicle group.