Yvonne G. Lin

Chronic stress promotes tumor growth and angiogenesis in a mouse model of ovarian carcinoma

Stress can alter immunological, neurochemical and endocrinological functions, but its role in cancer progression is not well understood. Here, we show that chronic behavioral stress results in higher levels of tissue catecholamines, greater tumor burden and more invasive growth of ovarian carcinoma cells in an orthotopic mouse model. These effects are mediated primarily through activation of the tumor cell cyclic AMP (cAMP)–protein kinase A (PKA) signaling pathway by the β2 adrenergic receptor (encoded by ADRB2). Tumors in stressed animals showed markedly increased vascularization and enhanced expression of VEGF, MMP2 and MMP9, and we found that angiogenic processes mediated the effects of stress on tumor growth in vivo. These data identify β-adrenergic activation of the cAMP–PKA signaling pathway as a major mechanism by which behavioral stress can enhance tumor angiogenesis in vivo and thereby promote malignant cell growth. These data also suggest that blocking ADRB-mediated angiogenesis could have therapeutic implications for the management of ovarian cancer.

Dicer, Drosha, and outcomes in patients with ovarian cancer.

BACKGROUND We studied Dicer and Drosha, components of the RNA-interference machinery, in ovarian cancer. METHODS We measured messenger RNA (mRNA) levels of Dicer and Drosha in specimens of invasive epithelial ovarian cancer from 111 patients, using a quantitative reverse-transcriptase-polymerase-chain-reaction assay, and compared the results with clinical outcomes. Validation was performed with the use of published microarray data from cohorts of patients with ovarian, breast, and lung cancer. Mutational analyses of genomic DNA from the Dicer and Drosha genes were performed in a subgroup of ovarian-cancer specimens. Dicer-dependent functional assays were performed by means of in vitro transfection with small interfering RNA (siRNA) and short hairpin RNA (shRNA). RESULTS Levels of Dicer and Drosha mRNA correlated with the levels of expression of the corresponding protein and were decreased in 60% and 51% of ovarian-cancer specimens, respectively. Low Dicer expression was significantly associated with advanced tumor stage (P=0.007), and low Drosha expression with suboptimal surgical cytoreduction (P=0.02). Cancer specimens with both high Dicer expression and high Drosha expression were associated with increased median survival (>11 years, vs. 2.66 years for other subgroups; P<0.001). We found three independent predictors of reduced disease-specific survival in multivariate analyses: low Dicer expression (hazard ratio, 2.10; P=0.02), high-grade histologic features (hazard ratio, 2.46; P=0.03), and poor response to chemotherapy (hazard ratio, 3.95; P<0.001). Poor clinical outcomes among patients with low Dicer expression were validated in additional cohorts of patients. Rare missense mutations were found in the Dicer and Drosha genes, but their presence or absence did not correlate with the level of expression. Functional assays indicated that gene silencing with shRNA, but not siRNA, may be impaired in cells with low Dicer expression. CONCLUSIONS Our findings indicate that levels of Dicer and Drosha mRNA in ovarian-cancer cells have associations with outcomes in patients with ovarian cancer.

Curcumin Inhibits Tumor Growth and Angiogenesis in Ovarian Carcinoma by Targeting the Nuclear Factor-κB Pathway

Purpose: Curcumin, a component of turmeric, has been shown to suppress inflammation and angiogenesis largely by inhibiting the transcription factor nuclear factor-κB (NF-κB). This study evaluates the effects of curcumin on ovarian cancer growth using an orthotopic murine model of ovarian cancer. Experimental Design:In vitro and in vivo experiments of curcumin with and without docetaxel were done using human ovarian cancer cell lines SKOV3ip1, HeyA8, and HeyA8-MDR in athymic mice. NF-κB modulation was ascertained using electrophoretic mobility shift assay. Evaluation of angiogenic cytokines, cellular proliferation (proliferating cell nuclear antigen), angiogenesis (CD31), and apoptosis (terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling) was done using immunohistochemical analyses. Results: Curcumin inhibited inducible NF-κB activation and suppressed proliferation in vitro. In vivo dose-finding experiments revealed that 500 mg/kg orally was the optimal dose needed to suppress NF-κB and signal transducers and activators of transcription 3 activation and decrease angiogenic cytokine expression. In the SKOV3ip1 and HeyA8 in vivo models, curcumin alone resulted in 49% (P = 0.08) and 55% (P = 0.01) reductions in mean tumor growth compared with controls, whereas when combined with docetaxel elicited 96% (P < 0.001) and 77% reductions in mean tumor growth compared with controls. In mice with multidrug-resistant HeyA8-MDR tumors, treatment with curcumin alone and combined with docetaxel resulted in significant 47% and 58% reductions in tumor growth, respectively (P = 0.05). In SKOV3ip1 and HeyA8 tumors, curcumin alone and with docetaxel decreased both proliferation (P < 0.001) and microvessel density (P < 0.001) and increased tumor cell apoptosis (P < 0.05). Conclusions: Based on significant efficacy in preclinical models, curcumin-based therapies may be attractive in patients with ovarian carcinoma.

Focal Adhesion Kinase Targeting Using In vivo Short Interfering RNA Delivery in Neutral Liposomes for Ovarian Carcinoma Therapy

Purpose: Focal adhesion kinase (FAK) plays a critical role in ovarian cancer cell survival and in various steps in the metastatic cascade. Based on encouraging in vitro results with FAK silencing, we examined the in vivo therapeutic potential of this approach using short interfering RNA (siRNA) in the neutral liposome 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC). Experimental Design: Therapy experiments of FAK siRNA with or without docetaxel were done using human ovarian cancer cell lines SKOV3ip1, HeyA8, and HeyA8MDR in nude mice. Additional experiments with a cisplatin-resistant cell line (A2780-CP20) were also done. Assessments of angiogenesis (CD31), cell proliferation (proliferating cell nuclear antigen), and apoptosis (terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling) were done using immunohistochemical analysis. Results: A single dose of FAK siRNA-DOPC was highly effective in reducing in vivo FAK expression for up to 4 days as assayed by Western blot and immunohistochemical analysis. Therapy experiments were started 1 week after injection of the ovarian cancer cells. Treatment with FAK siRNA-DOPC (150 μg/kg twice weekly) reduced mean tumor weight by 44% to 72% in the three cell lines compared with the control group (Ps < 0.05 for HeyA8, A2780-CP20, and SKOV3ip1). When FAK siRNA-DOPC was combined with docetaxel, there was even greater reduction in mean tumor weight in all models (all Ps < 0.05). Similar results were observed in combination with cisplatin. Treatment with FAK siRNA-DOPC plus docetaxel resulted in decreased microvessel density, decreased expression of vascular endothelial growth factor and matrix metalloproteinase-9, and increased apoptosis of tumor-associated endothelial cells and tumor cells. Conclusions: Taken together, these findings suggest that FAK siRNA-DOPC plus docetaxel or platinum might be a novel therapeutic approach against ovarian cancer.

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.

Therapeutic Efficacy of a Novel Focal Adhesion Kinase Inhibitor TAE226 in Ovarian Carcinoma

Focal adhesion kinase (FAK) overexpression is frequently found in ovarian and other cancers and is predictive of poor clinical outcome. In the current study, we characterized the biological and therapeutic effects of a novel FAK inhibitor, TAE226. Taxane-sensitive (SKOV3ip1 and HeyA8) and taxane-resistant (HeyA8-MDR) cell lines were used for in vitro and in vivo therapy experiments using TAE226 alone and in combination with docetaxel. Assessment of cytotoxicity, cell proliferation [proliferating cell nuclear antigen (PCNA)], angiogenesis (CD31), and apoptosis (terminal nucleotidyl transferase-mediated nick end labeling) were done by immunohistochemistry and immunofluorescence. In vitro, TAE226 inhibited the phosphorylation of FAK at both Y397 and Y861 sites, inhibited cell growth in a time- and dose-dependent manner, and enhanced docetaxel-mediated growth inhibition by 10- and 20-fold in the taxane-sensitive and taxane-resistant cell lines, respectively. In vivo, FAK inhibition by TAE226 significantly reduced tumor burden in the HeyA8, SKOV3ip1, and HeyA8-MDR models (46-64%) compared with vehicle-treated controls. However, the greatest efficacy was observed with concomitant administration of TAE226 and docetaxel in all three models (85-97% reduction, all P values <0.01). In addition, TAE226 alone and in combination with chemotherapy significantly prolonged survival in tumor-bearing mice. Even in larger tumors, combination therapy with TAE226 and docetaxel resulted in tumor regression. The therapeutic efficacy was related to reduced pericyte coverage, induction of apoptosis of tumor-associated endothelial cells, and reduced microvessel density and tumor cell proliferation. The novel FAK inhibitor, TAE226, offers an attractive therapeutic approach in ovarian carcinoma.

Adrenergic modulation of focal adhesion kinase protects human ovarian cancer cells from anoikis

Chronic stress is associated with hormonal changes that are known to affect multiple systems, including the immune and endocrine systems, but the effects of stress on cancer growth and progression are not fully understood. Here, we demonstrate that human ovarian cancer cells exposed to either norepinephrine or epinephrine exhibit lower levels of anoikis, the process by which cells enter apoptosis when separated from ECM and neighboring cells. In an orthotopic mouse model of human ovarian cancer, restraint stress and the associated increases in norepinephrine and epinephrine protected the tumor cells from anoikis and promoted their growth by activating focal adhesion kinase (FAK). These effects involved phosphorylation of FAKY397, which was itself associated with actin-dependent Src interaction with membrane-associated FAK. Importantly, in human ovarian cancer patients, behavioral states related to greater adrenergic activity were associated with higher levels of pFAKY397, which was in turn linked to substantially accelerated mortality. These data suggest that FAK modulation by stress hormones, especially norepinephrine and epinephrine, can contribute to tumor progression in patients with ovarian cancer and may point to potential new therapeutic targets for cancer management.

An anticancer C-Kit kinase inhibitor is reengineered to make it more active and less cardiotoxic

Targeting kinases is central to drug-based cancer therapy but remains challenging because the drugs often lack specificity, which may cause toxic side effects. Modulating side effects is difficult because kinases are evolutionarily and hence structurally related. The lack of specificity of the anticancer drug imatinib enables it to be used to treat chronic myeloid leukemia, where its target is the Bcr-Abl kinase, as well as a proportion of gastrointestinal stromal tumors (GISTs), where its target is the C-Kit kinase. However, imatinib also has cardiotoxic effects traceable to its impact on the C-Abl kinase. Motivated by this finding, we made a modification to imatinib that hampers Bcr-Abl inhibition; refocuses the impact on the C-Kit kinase; and promotes inhibition of an additional target, JNK, a change that is required to reinforce prevention of cardiotoxicity. We established the molecular blueprint for target discrimination in vitro using spectrophotometric and colorimetric assays and through a phage-displayed kinase screening library. We demonstrated controlled inhibitory impact on C-Kit kinase in human cell lines and established the therapeutic impact of the engineered compound in a novel GIST mouse model, revealing a marked reduction of cardiotoxicity. These findings identify the reengineered imatinib as an agent to treat GISTs with curbed side effects and reveal a bottom-up approach to control drug specificity.

Surgical stress promotes tumor growth in ovarian carcinoma.

Purpose: Surgical stress has been suggested to facilitate the growth of preexisting micrometastases as well as small residual tumor postoperatively. The purpose of this study was to examine the effects of surgical stress on ovarian cancer growth and to determine underlying mechanisms responsible for increased growth. Experimental Design: To mimic the effects of surgery, we did a laparotomy or mastectomy under isoflurane inhalation on athymic nude mice 4 days after i.p. tumor cell injection. Propranolol infusion via Alzet pumps was used to block the influence of sympathetic nervous system activation by surgical stress. Results: In both HeyA8 and SKOV3ip1 models, the mice in the laparotomy and mastectomy groups had significantly greater tumor weight (P < 0.05) and nodules (P < 0.05) compared with anesthesia only controls. There was no increase in tumor weight following surgery in the β-adrenergic receptor–negative RMG-II model. Propranolol completely blocked the effects of surgical stress on tumor growth, indicating a critical role for β-adrenergic receptor signaling in mediating the effects of surgical stress on tumor growth. In the HeyA8 and SKOV3ip1 models, surgery significantly increased microvessel density (CD31) and vascular endothelial growth factor expression, which were blocked by propranolol treatment. Conclusion: These results indicate that surgical stress could enhance tumor growth and angiogenesis, and β-blockade might be effective in preventing such effects.

Therapeutic Targeting of Neuropilin-2 on Colorectal Carcinoma Cells Implanted in the Murine Liver

BACKGROUND Neuropilin-2 (NRP2) is a high-affinity kinase-deficient receptor for vascular endothelial growth factor (VEGF) and semaphorin 3F. We investigated its function in human colorectal cancers. METHODS Immunohistochemistry and immunoblotting were used to assess NRP2 expression levels in colorectal tumors and colorectal cancer cell lines, respectively. HCT-116 colorectal cancer cells stably transfected with short hairpin RNA (shRNAs) against NRP2 or control shRNAs were assayed for proliferation by the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and for activation of the VEGFR1 pathway by immunoblotting. Soft agar assays, Annexin V staining, and Boyden chamber assays were used to examine anchorage-independent growth, apoptosis in response to hypoxia, and cell migration/invasion, respectively, in HCT-116 transfectants. Tumor growth and metastasis were analyzed in mice (groups of 10) injected with shRNA-expressing HCT-116 cells. The effect of in vivo targeting of NRP2 by small interfering RNA (siRNA) on the growth of hepatic colorectal tumors derived from luciferase-expressing HCT-116 cells was assessed by measuring changes in bioluminescence and final tumor volumes. All statistical tests were two-sided. RESULTS NRP2 expression was substantially higher in tumors than in adjacent mucosa. HCT-116 transfectants with reduced NRP2 levels had reduced VEGFR1 signaling, but proliferation was unchanged. Anchorage-independent growth, survival under hypoxic conditions, and motility/invasiveness were also reduced. In vivo, HCT-116 transfectants with reduced NRP2 demonstrated decreased tumor growth, fewer metastases, and increased apoptosis compared with control cells. Hepatic colorectal tumors in mice treated with NRP2 siRNAs were statistically significantly smaller than those in mice treated with control siRNAs (at 28 days after implantation, mean control siRNAs = 420 mm3, mean NRP2 siRNAs = 36 mm3, NRP2 vs control: difference = 385 mm3, 95% confidence interval = 174 mm3 to 595 mm3, P = .005). CONCLUSION NRP2 on colorectal carcinoma cells is important for tumor growth and is a potential therapeutic target in human cancers where it is expressed.