In vivo imaging of lymph node metastasis with telomerase-specific replication-selective adenovirus

Abstract

Currently available methods for detection of tumors in vivo such as computed tomography and magnetic resonance imaging are not specific for tumors. Here we describe a new approach for visualizing tumors whose fluorescence can be detected using telomerase-specific replication-competent adenovirus expressing green fluorescent protein (GFP) (OBP-401). OBP-401 contains the replication cassette, in which the human telomerase reverse transcriptase (hTERT) promoter drives expression of E1 genes, and the GFP gene for monitoring viral replication. When OBP-401 was intratumorally injected into HT29 tumors orthotopically implanted into the rectum in BALB/c nu/nu mice, para-aortic lymph node metastasis could be visualized at laparotomy under a three-chip color cooled charged-coupled device camera. Our results indicate that OBP-401 causes viral spread into the regional lymphatic area and selectively replicates in neoplastic lesions, resulting in GFP expression in metastatic lymph nodes. This technology is adaptable to detect lymph node metastasis in vivo as a preclinical model of surgical navigation.

A simple detection system for adenovirus receptor expression using a telomerase-specific replication-competent adenovirus

“…32,34 The virus was purified by ultracentrifugation using cesium chloride step gradients. Viral titers were determined by a plaque-forming assay using 293 cells and viruses were stored at À80 1C.…”

“…Furthermore, we recently generated a green fluorescent protein (GFP)-expressing telomerase-specific replication-competent adenovirus OBP-401, which induces ectopic GFP expression in tumor cells, but not in normal cells. 32 OBP-401 infection efficiently induces GFP expression in metastatic tumor cells at regional lymph nodes 32 and liver, 33 circulating tumor cells in blood flow 34 and disseminated tumor cells in the abdominal cavity. 35 These results suggest that OBP-401 is a highly sensitive tool for the detection of tumor cells.…”

Potent antitumor effects of combined therapy with a telomerase-specific, replication-competent adenovirus (OBP-301) and IL-2 in a mouse model of renal cell carcinoma

“…8,13 A replication-selective, tumor-specific adenoviral agent, OBP-301, was constructed for development of a cancer-specific therapeutic modality. OBP-301 has potent anticancer activities against many types of human malignancies such as lung, colon and prostate cancer.…”

“…Previous study developed a unique strategy for oncolytic virotherapy based on the replicative capacity of the adenovirus by placing the envelope-1 (E1) gene under the control of an hTERT promoter. [6][7][8][9][10] OBP-301 (telomelysin), a cancer-selective, replication-competent oncolytic adenovirus, can induce cell lysis in human non-small-cell lung cancer and prostate cancer cells. 6,9 OBP-301 has the ability to replicate within tumors, enter the blood circulation and then replicate in distant metastatic tumors after the intratumoral administration.…”

Use of the Rad51 promoter for targeted anti-cancer therapy

“…This can be accomplished through packaging the constructs in a viral vector system. Studies using the hTERT promoter have used both replication-defective (45) and replication-competent (46,47) adenovirus as means for successful in vivo gene delivery. Pseudotyped lentiviral vectors targeted to prostate cells containing a prostate-specific promoter to control gene-of-interest expression have also been used (48).…”