Construction of conditionally replicating adenovirus expressing staphylococcal enterotoxin A gene: potential usefulness for anti-tumor therapies.

OBJECTIVE: The aim of this study was to construct a conditionally replicating adenovirus pPE3-SEA expressing staphylococcal enterotoxin A (SEA) gene. MATERIALS AND METHODS: A full-length SEA gene fragment was cloned into pENTR12 plasmid to obtain a recombinant viral plasmid pENTR12-SEA. The pENTR12-SEA plasmid was co-transfected into HEK293 cells along with pPE3-ccdB, which encoded for the virus backbone, to generate recombinant adenovirus pPE3-SEA vector. Amplified pPE3-SEA vectors were purified, and viral titer was determined using the 50% tissue culture infective dose method. RESULTS: The PCR, restriction enzyme digestion, and sequence analyses proved successful construction of replicating oncolytic adenovirus pENTR12-SEA and recombinant SEA expressing oncolytic adenovirus pPE3-SEA. The viral titer was 2.5 × 1010 pfu/ml. CONCLUSIONS: We successfully constructed conditionally replicating adenovirus pPE3-SEA which can be utilized for experimental studies of tumor-targeted therapies.

Cbl-b gene silencing in splenic T lymphocytes as a therapeutic strategy to target the prostate cancer RM-1 cell tumors in immune competent mice.

OBJECTIVE: In recent years, the field of cancer immunotherapy has become a research hotspot and is currently faced with numerous challenges. The objective of this study was to assess the success of cbl-b gene silencing in splenic T lymphocytes as an immune strategy to target the murine prostate cancer RM-1 cells in vitro and solid tumors in vivo. MATERIALS AND METHODS: For this purpose, cbl-b gene-specific siRNA was designed, synthesized, and was transfected into mouse splenic T lymphocytes, followed by assessment of T cell activation, TH1 cytokine production, and in vitro cytotoxicity against RM-1 cell targets. For in vivo cytotoxicity studies, first the RM-1 tumor model was established in immune competent mice that were later tumor-injected with splenic T lymphocytes transfected with specific shRNA for cbl-b gene silencing. RESULTS: The data show that the cbl-b gene silencing in T lymphocytes resulted in an enhanced surface expression of CD69 activation marker, elevated production of interleukin (IL)-2 and interferon (IFN)-γ, and their increased cytotoxicity as effectors against RM-1 prostate cancer cells. The tumor injection with cbl-b shRNA-transfected T lymphocytes also resulted in significant reduction of the tumor size as compared with controls. CONCLUSIONS: cbl-b gene silencing strategy enhanced the immune function of T lymphocytes, increased their cytotoxic potential against RM-1 prostate cancer cells, as well as caused significant suppression of the tumor growth in immune competent mice.