Treatment of Colon Cancer with Oncolytic Herpes Simplex Virus in Preclinical Models

Cancer stem cells (CSCs), which are a rare population in any type of cancer, including colon cancer, are tumorigenic and responsible for cancer recurrence and metastasis. CSCs have been isolated from a number of different solid tumors recently, although the isolation of CSCs in colon cancer is still challenging. We cultured colon cancer cells in stem cell medium to obtain colonosphere cells. These cells possessed the characteristics of CSCs, with a high capacity of tumorigenicity, migration and invasion in vitro and in vivo. The isolation and identification of CSCs have provided new targets for the therapeutics. Oncolytic herpes simplex viruses (oHSV) are an effective strategy for killing colon cancer cells in preclinical models. Here, we examined the efficacy of an oncolytic herpes simplex virus type 2 (oHSV2) in killing colon cancer cells and colon cancer stem-like cells (CSLCs). oHSV2 was found to be highly cytotoxic to the adherent and sphere cells in vitro, and oHSV2 treatment in vivo significantly inhibited tumor growth. This study demonstrates that oHSV2 is effective against colon cancer cells and colon CSLCs and could be a promising strategy for treating colon cancer patients.