Tumour overexpression of inducible nitric oxide synthase (iNOS) increases angiogenesis and may modulate the anti-tumour effects of the vascular disrupting agent ZD6126.
Tumours derived from DLD-1 colon adenocarcinoma cells, transfected to either overexpress inducible nitric oxide synthase (clone iNOS-19) or with empty vector (pBAN2R), were utilised to test the hypothesis that tumour expression of iNOS (a) increases tumour angiogenesis and (b) modulates the anti-tumour activity of the vascular disrupting agent ZD6126. Overexpression of iNOS by clone iNOS-19 cells and murine xenografts was confirmed by the Griess assay and western blot analysis respectively. Clone iNOS-19 tumours grew more rapidly than pBAN2R tumours. Tumour perfusion, assessed by Hoechst 33342 uptake, was significantly greater in the clone iNOS-19 tumours (P < 0.001). A significant reduction in the perfusion of only the pBAN2R tumours, compared with control, was obtained 24 h after treatment with an intermediate dose of 100 mg/kg ZD6126 (P < 0.001), whereas 200 mg/kg significantly reduced the perfusion of both tumour types (P < 0.001). Whilst pBAN2R tumour necrosis increased in a dose-dependent manner, significant at 100 and 200 mg/kg ZD6126 (P < 0.05), intermediate doses did not induce a similar degree of necrosis in clone iNOS-19 tumours. A significant reduction in splenic perfusion was found 24 h after treatment with 100 mg/kg ZD6126, primarily associated with the red pulp. Overexpression of iNOS increases tumour growth, the degree of functionally perfused vasculature and angiogenesis, and also confers resistance to the vascular disrupting agent ZD6126.
Cullis
Elizabeth R
ER
Division of Basic Medical Sciences, St. George's, University of London, Cranmer Terrace, London SW17 ORE, UK.
Kalber
Tammy L
TL
Ashton
Susan E
SE
Cartwright
Judith E
JE
Griffiths
John R
JR
Ryan
Anderson J
AJ
Robinson
Simon P
SP
D000230:Adenocarcinoma / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000201:enzymology* / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D013997:Time Factors; D014183:Transplantation, Heterologous
D000970:Antineoplastic Agents; C455219:N-acetylcochinol-O-phosphate; D009943:Organophosphorus Compounds; D052247:Nitric Oxide Synthase Type II