Abstract 3541: Therapeutic effect of CD133-targeted oncolytic adenovirus in colon cancer
Authors: Sato Mizuho , Miura Yoshiaki , Yamamoto Masato 
Published: August 2015

Abstract
CD133 (Prominin-1), a member of the transmembrane glycoprotein family is a cell surface marker cancer stem cells (CSCs) in many malignancies. In colorectal cancer, CD133 expression was correlated with recurrence, metastases and chemotherapy resistance, as well as poor survival. It is thus reasonable to develop novel therapeutic strategies to target CD133 positive cancer cells in order to attack colon cancer stem cells. We have been developing therapeutic approaches based on the oncolytic adenovirus, and have recently established a method for isolating transductionally-targeted adenovirus by high-throughput screening. In this study, in order to development for new CSCs-targeted therapeutic strategies, we isolated the CD133-specific Oncolytic Adenovirus (OAd) and tested the oncolytic activity of CD133-targeted OAd.
We established the 293 cells overexpressing CD133 (293-CD133), and the fiber-modified Ad library was screened by infecting this cell line. Random sequences in the initial library started to converge after first round and resulted in a single clone (TYMLSRN) after the 4th round. CD133-targeted OAd (AdML-TYML) showed strong binding to CD133-positive cells (293-CD133 and LoVo (CD133 (+) human colon carcinoma)), not to CD133-negative cells (parental 293 and LS174T (CD133 (-) human colon carcinoma)). In addition, the anti-CD133 antibody inhibited the binding of AdML-TYML to CD133. To assess the cytopathic effect of CD133-targeted OAd, human colon cancer cell lines (LoVo and LS174T) were infected and the cytocidal effect was assessed by crystal violet staining. AdML-TYML showed strong oncolysis selectively in LoVo cells, whereas there was no effect on LS174T cells.
In order to assess the in vivo function of AdML-TYML, tumor formation assay was performed. AdML-TYML infection resulted in complete blockage of the tumor formation of CD133-positive LoVo cells. 100% of the mice inoculated with non-infected LoVo cells had developed tumors, while 0% of the mice inoculated with AdML-TYML infected LoVo cells had done so. Contrarily, there was no difference between non-infected cells (100%) and infected cells (75%) in CD133-negative LS174T cells. These results indicate that CD133-targeted OAd leads to a reduction in tumor formation of CD133-positive cell lines in vivo.
We focused on the CD133 as a target molecule of CSCs in colon cancer and successfully identified potent CD133-targeting OAd using high-throughput screening system. The CD133-targeted OAd exhibited selective infectivity and oncolysis to CD133-positive cells and anti-tumorigenic activity against colon cancer cells. The same approach can be applied to other cancers whose CSC marker is CD133. The ability of CSCs-targeted Ad such as CD133-targeted OAd to infect and kill CSCs has important implications for the prevention of metastases and relapses in a variety of cancers.
Citation Format: Mizuho Sato, Yoshiaki Miura, Masato Yamamoto. Therapeutic effect of CD133-targeted oncolytic adenovirus in colon cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3541. doi:10.1158/1538-7445.AM2015-3541