Effect of interleukin-8 gene silencing with liposome-encapsulated small interfering RNA on ovarian cancer cell growth.
BACKGROUND
Interleukin-8 (IL-8) is a proangiogenic cytokine that is overexpressed in many human cancers. We investigated the clinical and biologic significance of IL-8 in ovarian carcinoma using human samples and orthotopic mouse models.


METHODS
Tumor expression of IL-8 was assessed by immunohistochemistry among ovarian cancer patients (n = 102) with available clinical and survival data. We examined the effect of IL-8 gene silencing with small interfering RNAs incorporated into neutral liposomes (siRNA-DOPCs), alone and in combination with docetaxel, on in vivo tumor growth, angiogenesis (microvessel density), and tumor cell proliferation in mice (n = 10 per treatment group) bearing orthotopic taxane-sensitive (HeyA8 and SKOV3ip1) and taxane-resistant (SKOV3ip2.TR) ovarian tumors. All statistical tests were two-sided.


RESULTS
Of the 102 cancer specimens, 43 (42%) had high IL-8 expression and 59 (58%) had low or no IL-8 expression; high IL-8 expression was associated with advanced tumor stage (P = .019), high tumor grade (P = .031), and worse survival (median survival for patients with high vs low IL-8 expression: 1.62 vs 3.79 years; P < .001). Compared with empty liposomes, IL-8 siRNA-DOPC reduced the mean tumor weight by 32% (95% confidence interval [CI] = 14% to 50%; P = .03) and 52% (95% CI = 27% to 78%; P = .03) in the HeyA8 and SKOV3ip1 mouse models, respectively. In all three mouse models, treatment with IL-8 siRNA-DOPC plus the taxane docetaxel reduced tumor growth the most compared with empty liposomes (77% to 98% reduction in tumor growth; P < .01 for all). In the HeyA8 and SKOV3ip1 models, tumors from mice treated with IL-8 siRNA-DOPC alone had lower microvessel density than tumors from mice treated with empty liposomes (HeyA8: 34% lower, 95% CI = 32% to 36% lower [P = .002]; SKOV3ip1: 39% lower, 95% CI = 34% to 44% lower [P = .007]). Compared with empty liposomes, IL-8 siRNA-DOPC plus docetaxel reduced tumor cell proliferation by 35% (95% CI = 25% to 44%; P < .001) and 38% (95% CI = 28% to 48%; P < .001) in the HeyA8 and SKOV3ip1 models, respectively.


CONCLUSIONS
Increased IL-8 expression is associated with poor clinical outcome in human ovarian carcinoma, and IL-8 gene silencing decreases tumor growth through antiangiogenic mechanisms.
Merritt
William M
WM
Department of Gynecologic Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX, USA.
Lin
Yvonne G
YG
Spannuth
Whitney A
WA
Fletcher
Mavis S
MS
Kamat
Aparna A
AA
Han
Liz Y
LY
Landen
Charles N
CN
Jennings
Nicholas
N
De Geest
Koen
K
Langley
Robert R
RR
Villares
Gabriel
G
Sanguino
Angela
A
Lutgendorf
Susan K
SK
Lopez-Berestein
Gabriel
G
Bar-Eli
Menashe M
MM
Sood
Anil K
AK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D014408:Biomarkers, Tumor / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D000077143:Docetaxel; D042783:Endothelial Cells; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D016209:Interleukin-8 / Q000235:genetics*; D053208:Kaplan-Meier Estimate; D008081:Liposomes; D051379:Mice; D008819:Mice, Nude; D008833:Microcirculation; D008875:Middle Aged; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009389:Neovascularization, Pathologic; D010051:Ovarian Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000235:genetics*; D010766:Phosphorylation; D011379:Prognosis; D016016:Proportional Hazards Models; D034741:RNA, Small Interfering / Q000008:administration & dosage*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D043823:Taxoids / Q000008:administration & dosage*; D015854:Up-Regulation
D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D016209:Interleukin-8; D008081:Liposomes; D034741:RNA, Small Interfering; D043823:Taxoids; D000077143:Docetaxel; D048052:Mitogen-Activated Protein Kinase 3