Adenoviral-mediated gene transfer of a constitutively active retinoblastoma gene inhibits human pancreatic tumor cell proliferation.

BACKGROUND: The development of pancreatic cancer involves an accumulation of genetic changes, including oncogene activation and mutations in tumor suppressor genes important in cell cycle regulation. As a step to developing gene therapies to restore cell cycle control, we hypothesized that adenoviral-mediated gene transfer of a constitutively active, nonphosphorylatable form of the retinoblastoma gene (AdRb) would inhibit human pancreatic tumor cell proliferation. METHODS: Transfection efficiency was assessed by beta-gal staining with an adenovirus expressing the beta-galactosidase gene (AdLacZ). The effect of AdRb on DNA synthesis in pancreatic cancer cell lines was determined by tritiated thymidine incorporation. Western blotting with an antihemagglutinin antibody directed to the hemagglutinin-tagged AdRb construct was performed to confirm transfection of pancreatic cancer cells. Apoptosis was evaluated with a TUNEL assay. RESULTS: Efficient transfection of human pancreatic cancer cell lines was achieved with AdLacZ. AdRb inhibited tritiated thymidine uptake in the cancer cell lines BxPC-3, MIA PaCa-2, and PANC-1. Western blotting confirmed transfection of cancer cells with AdRb. AdRb did not inhibit growth by apoptosis. CONCLUSIONS: Adenoviral-mediated gene delivery of constitutively active Rb produces significant growth inhibition in human pancreatic cancer cell lines and is not a result of apoptosis. Further studies examining the role of Rb in pancreatic cancer are warranted.

Isolation and characterization of a novel bacterium growing via reductive dehalogenation of 2-chlorophenol.

A bacterium capable of anaerobic growth via reductive dehalogenation of 2-chlorophenol was isolated from a culture enriched from sediment taken from a small stream near Lansing, Mich. The organism, designated strain 2CP-1, is a gram-negative rod ca. 3 by 0.5 micron in size and is a catalase-negative, oxidase-negative, facultative anaerobe that forms small red colonies in anaerobic media. The organism grew in reduced anaerobic mineral medium supplemented with 2-chlorophenol, acetate, and vitamins, producing phenol as a product. It did not grow when either 2-chlorophenol or acetate was omitted. The growth yield was about 3 g of protein per mol of 2-chlorophenol dechlorinated, and the doubling time was 3.7 days. Only the ortho position was dehalogenated, and additional chlorines at other positions decreased or blocked ortho dechlorination. The organism also grew with fumarate as its electron acceptor. Dechlorination activity is inducible, since cultures grown in fumarate containing medium with 2-chlorophenol rapidly dechlorinated additional 2-chlorophenol, while cultures grown in the same medium without 2-chlorophenol did not. Analysis of the organism's 16S rRNA sequence revealed that it is a member of the delta proteobacteria, more closely related to the myxobacteria than to the sulfidogenic bacteria.