13P - Targeting unfolded protein response sensitizes urothelial carcinoma cells to cisplatin chemotherapy

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Cytotoxic agents
Cancer biology
Urothelial Cancers
Personalised/Precision medicine
Presenter Kyung Seok Han
Citation Annals of Oncology (2016) 27 (suppl_9): ix1-ix8. 10.1093/annonc/mdw573
Authors K.S. Han1, J.J. Kim1, J.G. Lee1, J.J. Oh1, S.C. Lee1, S.E. Lee2, S. Byun1
  • 1Department Of Urology, Seoul National University Bundang Hospital, 463-010 - Gyeonggi-do/KR
  • 2Department Of Urology, Seoul National University Bundang Hospital, Gyeonggi-do/KR

Abstract

Background

Chemotherapy deprives tumors of essential resources for cancer cell survival. These environmental stressors generally induce the accumulation of unfolded proteins in the endoplasmic reticulum (ER) of cancer cell. There, they elicit the unfolded protein response (UPR), which is a general cellular defense mechanism to protect cells from stress. We investigated a potential role of GRP78 as a combined therapeutic target in urothelial carcinoma.

Methods

Urothelial cancer cell lines were used to investigate the effect of GRP78 knockdown, performed by small interfering RNA. Stably GRP78 knocked-down UC-3 cells were developed to investigate the role of GRP78 in cancer cell. After transient transfection, crystal violet assay and cell cycle analysis using FACS were performed to check the effect of GRP78 on tumor growth and cell cycle. In vivo system expressing GRP78 by doxycycline were developed using UC-3 xenografts and treated with cisplatin to evaluate in vivo combination effects of GRP78 inhibition during cisplatin.

Results

GRP78 was highly expressed in UC-3 cells and moderately expressed in T24, 253J and KU1919 cells. Immunohistochemical staining showed increased expression of GRP78 in human bladder cancer tissues compared with normal bladder tissues. Transient knockdown of GRP78 using si-GRP78 inhibited tumor proliferation in UC-3 cells. GRP78 knockdown also increased sub G0 population of UC-3 cells in cell cycle analysis and also induced more apoptosis after cisplatin treatment compared to control. Western blot analysis showed increased expression of GRP78 during exposure to cisplatin in bladder cancer cells. Sequential cisplatin treatment after knockdown of GRP78 showed an additive effect but sequential GRP78 knockdown after cisplatin chemotherapy showed a synergistic effect in UC-3 xenografts.

Conclusions

GRP78 has a critical role in protecting urothelial carcinoma cells from apoptotic stress induced by chemotherapy. Targeting GRP78 sensitized urothelial carcinoma cells to cisplatin. These data suggest that GRP78 is a novel therapeutic target as a combination therapy with cisplatin in the management of urothelial carcinoma.

Clinical trial indentification

Legal entity responsible for the study

Kyung Seok Han

Funding

Korean National Research Foundation

Disclosure

All authors have declared no conflicts of interest.