Myxoma virus-mediated oncolysis of ascites-derived human ovarian cancer cells and spheroids is impacted by differential AKT activity.

Abstract

OBJECTIVE:

We propose that metastatic epithelial ovarian cancer (EOC) is a potential therapeutic target for the oncolytic agent, Myxoma virus (MYXV).

METHODS:

Primary EOC cells were isolated from patient ascites and cultured as adherent cells or in suspension using Ultra Low-Attachment dishes. MYXV expressing green fluorescent protein was used to infect cells and spheroids. Infection was monitored by fluorescence microscopy, viral titering and immunoblotting for M-T7 and M130 virus protein expression, and cell viability by alamarBlue assay. Akti-1/2 (5 μM) and rapamycin (20 nM) were used to assay the role of PI3K-AKT signaling in mediating MYXV infection.

RESULTS:

Ascites-derived EOC cells grown in adherent culture are effectively killed by MYXV infection. EOC cells grown in suspension to form three-dimensional EOC spheroids readily permit MYXV entry into cells, yet are protected from the cytopathic effects of late MYXV infection. Upon reattachment (to model secondary metastasis), EOC spheroids are re-sensitized to MYXV-mediated oncolysis. The critical determinant that facilitates efficient MYXV infection is the presence of an activated PI3K-AKT signaling pathway. Treatment with the specific AKT inhibitor Akti-1/2 reduces infection of monolayer EOC cells and spheroids. Direct infection of freshly-collected ascites demonstrated that 54.5% of patient samples were sensitive to MYXV-mediated oncolytic cell killing. We also demonstrate that factor(s) present in ascites may negatively impact MYXV infection and oncolysis of EOC cells, which may be due to a down-regulation in endogenous AKT activity.

CONCLUSIONS:

Differential activity of AKT serves as the mechanistic basis for regulating MYXV-mediated oncolysis of EOC spheroids during key steps of the metastatic program. In addition, we provide the first evidence that MYXV oncolytic therapy may be efficacious for a significant proportion of ovarian cancer patients with metastatic disease.

• Authors: Rohann J M Correa, Monica Komar, Jessica G K Tong, Milani Sivapragasam, Masmudur M Rahman, Grant McFadden, Gabriel E Dimattia, Trevor G Shepherd
• Journal: Gynecologic oncology (Gynecol Oncol) Vol. 125 Issue 2 Pg. 441-50 (May 2012) ISSN: 1095-6859 [Electronic] United States
• PMID: 22306204 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical References

• Green Fluorescent Proteins
• Phosphatidylinositol 3-Kinases
• Oncogene Protein v-akt

Topics

• Ascites (pathology)
• Carcinoma, Ovarian Epithelial
• Female
• Green Fluorescent Proteins (biosynthesis, genetics)
• Humans
• Microscopy, Fluorescence (methods)
• Myxoma virus (genetics, metabolism, physiology)
• Neoplasms, Glandular and Epithelial (enzymology, therapy, virology)
• Oncogene Protein v-akt (metabolism)
• Oncolytic Virotherapy (methods)
• Ovarian Neoplasms (enzymology, therapy, virology)
• Phosphatidylinositol 3-Kinases (metabolism)
• Spheroids, Cellular (pathology)
• Tumor Cells, Cultured