Login to Access Video or Poster Abstract: MP88-10
Sources of Funding: none

Introduction

Bladder cancer is the 6th most common cancer in the USA. The current standard therapy for the first line of metastatic or local advanced bladder cancer is combination therapy with cisplatin (CDDP) and gemcitabine (GEM). However 5-years survival is still below 50%; therefore additional therapy is needed._x000D_ LIM-SH3 domain protein 1 (LASP1), identified from cDNA library of metastatic axillary lymph nodes of breast cancer, has been shown to promote cancer progression and invasion in several malignancies. In bladder cancer, LASP1 expression associates with cell invasion and can be used for detecting bladder cancer. However, the anti-tumor effects of LASP1 knockdown in vivo as well as combination therapy with chemotherapy remain unclear. In this study, we investigated the anti-cancer activity of LASP1 knockdown in bladder cancer._x000D_

Methods

LASP1 gene expression of tumor samples is analyzed using the Affymetrix Exon Array. The LASP1 expression in several bladder cancer cell lines was assessed by Western blot analysis and quantitative reverse transcription-PCR. Silencing of LASP1 in vitro was achieved using siRNA. Cell growth was measured by crystal violet assay. Cell cycle distribution was analyzed by flow cytometry after double thymidine block. The In vivo effect of LASP1 antisense oligonucleotide (ASO) treatment was assessed in the T24 CDDP-R (cisplatin-resistant) orthotopic bladder cancer model.

Results

High LASP1 expression correlated with metastatic recurrence rate between patients. The LASP1 expression is higher in UC1 and T24 cells than in UC13 and UC6 cells. Knockdown of LASP1 using siRNA inhibited cell growth, and was accompanied by an increase in p21 and p27, and a decreased of cyclin D1. Flow cytometry revealed that LASP1 knockdown induced G1 arrest. Conversely, stable LASP1 overexpression drove cell growth with an increase of cyclin D1 in UC6 and UC3 cells. The treatment of CDDP and GEM induced LASP1 expression in Western Blotting. Furthermore, compared with parental cell line, LASP1 is higher in T24 CDDP-R and RT112 CDDP-R cells than in parental cells. LASP1 ASO inhibited cell growth in RT112 CDDP-R and T24 CDDP-R cells._x000D_ In the orthotopic bladder cancer model, systemic LASP1 ASO administration to athymic nude mice delayed tumor progression in T24 CDDP-R cells._x000D_

Conclusions

These data revealed that LASP1 inhibition might be as a promising novel therapeutics modality in the treatment of chemoresistant bladder cancer.

Funding

none