Affiliations: [a] Department of Imaging, Yantai Yu-Huang-Ding Hospital, Yantai, Shandong, China | [b] Department of Radiotherapy, Yantai Yu-Huang-Ding Hospital, Yantai, Shandong, China | [c] Department of Surgery, the Second Affiliated Hospital of Qingdao University, Qingdao, Shandong, China | [d] Department of Health Care, People's Hospital of Weifang, Weifang, Shandong, China
Correspondence:
[*]
Corresponding author: Linying Dou, Department of Health Care, People's Hospital of Weifang, Weifang, Shandong, China. E-mail:[email protected]
Note: [1] These authors were equal to the study.
Abstract: OBJECTIVE: Anaplastic thyroid carcinoma (ATC) is one of the most
aggressive human cancers and often shows resistance to multimodal
therapeutic approaches. It has been shown that the transcriptional repressor
Slug inhibits the chemotherapeutic agent-induced apoptosis of cancer cells.
We evaluated whether targeting of Slug could augment doxorubicin
(DOX)-induced apoptosis of ATC cells. We also determined changes in PUMA
(p53-upregulated modulator of apoptosis) expression levels to identify
possible mechanisms of their combined actions. METHODS: SW1736 cells
were transfected with Slug siRNA or/and PUMA siRNA and then exposed to DOX
(0.1, 1, and 5 μ M) for selected times. Scrambled siRNA was used as a
control. The effects on cell viability were determined via MTT assay.
Apoptosis was assessed using TUNEL assays and annexin V staining, and was
confirmed by flow cytometry analyses. Slug and PUMA levels were determined
using western blotting, RT-PCR and immunofluorescence analyses. We used a
subcutaneous implanted tumor model of SW1736 cells in nude mice to assess
the effects of Slug silencing in combination with DOX on tumor development.
Apoptosis was assessed via TUNEL assay. RESULTS: Targeting of Slug
using siRNA inhibits growth of SW1736 cells and sensitizes SW1736 cells to
DOX in vitro and vivo. Targeting of Slug combined with DOX led to lower cell
viability than treatment with DOX alone in SW1736 cells. TUNEL and flow
cytometry analyses showed that targeting of Slug enhanced DOX-induced
apoptosis of SW1736 cells. In addition, targeting of Slug increased PUMA
expression, and targeting of PUMA restored the chemoresistance of
SW1736/Slug siRNA cells to DOX. CONCLUSIONS: Knockdown of Slug
enhanced the antitumor activity of DOX in SW1736 cells via induction of PUMA
upregulation. Our results suggest that targeting of Slug has good potential
for the development of new therapeutic strategies for ATC.
