Expression of several genes in the human chromosome 3p21.3 homozygous deletion region by an adenovirus vector results in tumor suppressor activities in vitro and in vivo.

A group of candidate tumor suppressor genes (designated CACNA2D2, PL6, 101F6, NPRL2, BLU, RASSF1, FUS1, HYAL2, and HYAL1) has been identified in a 120-kb critical tumor homozygous deletion region (found in lung and breast cancers) of human chromosome 3p21.3. We studied the effects of six of these 3p21.3 genes (101F6, NPRL2, BLU, FUS1, HYAL2, and HYAL1) on tumor cell proliferation and apoptosis in human lung cancer cells by recombinant adenovirus-mediated gene transfer in vitro and in vivo. We found that forced expression of wild-type FUS1, 101F6, and NPRL2 genes significantly inhibited tumor cell growth by induction of apoptosis and alteration of cell cycle processes in 3p21.3 120-kb region-deficient (homozygous) H1299 and A549 cells but not in the 3p21.3 120-kb region-heterozygous H358 and the normal human bronchial epithelial cells. Intratumoral injection of Ad-101F6, Ad-FUS1, Ad-NPRL2, and Ad-HYAL2 vectors or systemic administration of protamine-complexed vectors significantly suppressed growth of H1299 and A549 tumor xenografts and inhibited A549 experimental lung metastases in nu/nu mice. Together, our results, coupled with other studies demonstrating a tumor suppressor role for the RASSSF1A isoform, suggest that multiple contiguous genes in the 3p21.3 120-kb chromosomal region may exhibit tumor suppressor activity in vitro and in vivo.

Increased uptake of liposomal-DNA complexes by lung metastases following intravenous administration.

We have investigated the effects of an improved liposomal formulation (extruded DOTAP:cholesterol (DOTAP:Chol)-DNA complex) on transgene expression in tumor cells and normal cells of murine and human origin both in vitro and in vivo. In vitro, transgene expression was significantly increased (P = 0.01) in human tumor cells compared to normal human cells. The increased transgene expression was due to increased uptake of the liposome-DNA complex by tumor cell phagocytosis. Furthermore, immunohistochemical analysis demonstrated a greater transgene expression in lung tumors than in surrounding normal tissues. Increased transgene expression due to enhanced uptake of the liposome-DNA complexes by tumor cells in vivo was also demonstrated using fluorescently labeled DOTAP:Chol liposomes. Finally, evaluation of lung tissue explants obtained from patients undergoing pulmonary resection demonstrated significantly higher (P = 0.001) transgene expression in tumor cells than in normal cells. Thus, we demonstrated that intravenous injection of DOTAP:Chol-DNA complex results in increased transgene expression in tumor and is due to increased phagocytosis of the complexes by tumor cells.