Effective treatment of human breast tumor in a mouse xenograft model with herpes simplex virus type 1 specifying the NV1020 genomic deletion and the gBsyn3 syncytial mutation enabling high viral replication and spread in breast cancer cells.
A new oncolytic and fusogenic herpes simplex virus type 1 (HSV-1) was constructed on the basis of the wildtype HSV-1(F) strain. To provide for safety and tumor selectivity, the virus carried a large deletion including one of the two alpha4, gamma(1)34.5, alpha0 genes and the latency-associated transcript region. The gamma(1)34.5 gene, a major neurovirulence factor, was replaced by a gene cassette constitutively expressing the red fluorescent protein gene. Homologous recombination was used to transfer the fusogenic gBsyn3 mutation to the viral genome to produce the OncSyn virus. OncSyn causes extensive virus-induced cell fusion (syncytia) and replicates to higher titers than the parental Onc and HSV-1(F) strains in breast cancer cells. Biochemical analysis revealed that the OncSyn virus retains a stable genome and expresses all major viral glycoproteins. A xenograft mouse model system using MDA-MB-435S-luc (MM4L) human breast cancer cells constitutively expressing the luciferase gene implanted within the interscapular region of animals was used to test the ability of the virus to inactivate breast tumor cells in vivo. Seventy-two mice bearing MM4L breast cancer xenografts were randomly divided into three groups and given two rounds of three consecutive intratumoral injections of OncSyn, inactivated OncSyn, or phosphate-buffered saline 3 days apart. A single round of virus injections resulted in a drastic reduction of tumor sizes (p <or= 0.0001) and diminution of chemiluminescence emitted by the cancer cells (p <or= 0.0002). This effect was enhanced by a second round of virus injections into the tumors 3 days after the first round (p <or= 0.0001). Systematic necropsy and pathological evaluation of the primary tumors revealed that the single round of injections resulted in extensive necrosis of tumor cells (p <or= 0.0001), which was enhanced by the second round of injections (p <or= 0.0002). Internal organs were not affected by virus inoculation. Mouse weights were not significantly impacted by any treatment during the course of the entire study (p = 0.46). These results show that the attenuated, fusogenic, and oncolytic HSV-1(F) virus strain OncSyn may effectively treat human breast tumors in vivo.
Israyelyan
Anna H
AH
Division of Biotechnology and Molecular Medicine and Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.
Melancon
Jeffrey M
JM
Lomax
Larry G
LG
Sehgal
Inder
I
Leuschner
Carola
C
Kearney
Michael T
MT
Chouljenko
Vladimir N
VN
Baghian
Abolghasem
A
Kousoulas
Konstantin G
KG
D000818:Animals; D001483:Base Sequence; D001943:Breast Neoplasms / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D017931:DNA Primers / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000473:pathology / Q000628:therapy; D008561:Membrane Fusion; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009368:Neoplasm Transplantation; D050130:Oncolytic Virotherapy / Q000379:methods*; D014183:Transplantation, Heterologous; D014779:Virus Replication / Q000235:genetics
D017931:DNA Primers