Page 9 - D. Cancer biology

Silencing of sirtuin 6 inhibits cell invasion and migration by targeting
matrix metalloproteinase-9 expression in human breast cancer cells

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On-Yu Hong , Hye-Yeon Jang , Hyun Jo Youn and Jong-Suk Kim 1*
1 Department of Biochemistry, Institute for Medical Sciences, Jeonbuk National University Medical School, Jeonju 54907, South Korea,
AIM BACKGROUND
we investigated the effect of the inhibition of SIRT6 on protein Sirtuin6 (Sirt6), a member of the sirtuins protein family, plays
kinase C (PKC) and cytokine mediated cancer cell invasion and various biological roles in cancer. Regulation of sirt6 is involved in
migration using MCF-7 and MDA-MDA-231 human breast cancer cell tumor progression, including cancer cell adhesion, invasion and
line. And, we also determined the association of SIRT6 on MMP-9 migration. Cancer invasion and migration required for metastasis
expression. are the main causes of death in breast cancer patients. Matrix
metalloproteinases (MMPs) are crucial to regulate extracellular
METHODS matrix (ECM) proteolysis. Especially gelatinases (MMP-9) has been
closely associated with metastasis.
We investigated the effect of Sirt6 on the invasive behavior of two breast
cancer cell lines (MCF-7 and MDA-MB-231), and cells were transfected with FIGURES
control siRNA or Sirt6 siRNA and then treated with TPA or TNF-α. MMP-9
secretion to media was analyzed by gelatin zymography (zymo-MMP-9). Figure 1
MMP-9 and Sirt6 protein expressions were analyzed by Western blotting
using β-actin as the internal control. MMP-9 and Sirt6 mRNA levels were
determined by RT-PCR using GAPDH as the internal control. . NF-κB-luc and
AP-1-luc reporters were co-transfected with TK (Renilla) reporter into both
cell lines. NF-κB and AP-1 promoter activities were determined using a dual-
luciferase reporter assay. Invasion and migration assay used chamber assay.
Invasion chambers were coated with Matrigel and migration chambers used
without Matrigel. Cells were seeded into upper chambers and TPA or TNF-α
were added to lower chambers, photographed under a light microscope at
40x.
RESULTS

In this study, I investigated the effect of Sirt6 on PKC Figure 2 Figure 3
activator and cytokine mediated cancer cell invasion
and migration in MCF-7 and MDA-MB-231 human
breast cancer cell lines. In both cells lines, TPA or
TNF-α increased MMP-9 expression, cell invasion
and migration, and these effects were abolished by
Sirt6 knockdown. On the other hand, Sirt6
overexpression synergistically increased TPA- and
TNF-α-induced MMP-9 expressions. The suppressive
effects of Sirt6 knockdown on TPA- and TNF-α- Figure 4
induced MMP-9 expressions were caused by
inhibition of the MAPK signaling pathway, NF-κB and
AP-1 transcriptional activities in breast cancer cells,
and treating cells with MAPK, NF-κB, and AP-1
inhibitors reduced MMP-9 expression. Our results
suggests the modulation of SIRT6 as one of the
therapeutic value for breast cancer metastasis by
identifying SIRT6 in breast cancer cell invasion and c D
migration.

Figure 1. Effect of Sirt6 on MMP-9 expression
Figure 2. Effect of Sirt6 on MAPKinase
Figure 3. Effects of Sirt6 on the activations of NF-κB
and AP-1
Figure 4. Sirt6 knockdown inhibited TPA- or TNF-α-
induced Matrigel invasion and migration
CONCLUSION REFERENCES ACKNOWLEDGEMENTS

In conclusion, the study shows that the 1. Noh EM, Lee YR, Hong OY, Jung SH, Youn HJ, This research was supported by Basic
anti-invasive effects of Sirt6 in breast Kim JS: Aurora kinases are essential for PKC- Science Research Program through the
cancer cells might be through inhibiting induced invasion and matrix metallo National Research Foundation of Korea
proteinase-9 expression in MCF-7 breast
the phosphorylation of MAPK and cancer cells. Oncol Rep 2015; 34:803-10 (NRF) funded by the Ministry of Education
reducing AP-1 and NF-κB DNA-binding (2020R1I1A1A01054100)
activities and thus, MMP-9 down- 2. Bae JS, Noh SJ, Kim KM, Park SH, Hussein UK,
regulation. Park HS, Park BH, Ha SH, Lee H, Chung MJ, Contact information
:
Moon WS, Cho DH, Jang KY SIRT6 Is Involved
These results suggest modulation of Sirt6 in the Progression of Ovarian Carcinomas On-yu Hong. Ph.D,
offers a potential means for targeting via β-Catenin-Mediated Epithelial to Department of Biochemistry, Jeonbuk
breast cancer metastasis. Mesenchymal Transition. Front Oncol 2018; National University Medical school
8:538
E-mail: khong9053@naver.com