A cyclooxygenase-2 inhibitor (SC-58125) blocks growth of established human colon cancer xenografts

The Potential Therapeutic Value of Aspirin in Anaplastic Thyroid Cancer

Background: several experimental findings and epidemiological observations indicated that aspirin/acetylsalicylic acid (ASA) may be endowed with anticancer effects against a variety of human malignancies, including thyroid carcinomas. Among these, undifferentiated/anaplastic thyroid carcinoma (ATC) is one of the most aggressive and lethal human cancers, refractory to all currently available therapies. Methods: we here evaluated in a preclinical setting the effects of ASA on a panel of three ATC-derived cell lines: the CAL-62, the 8305C, and the 8505C. Results: the data obtained demonstrated the ability of ASA to inhibit, in a dose- and time-dependent manner, the proliferation of all ATC cell lines investigated, with IC50 values comprised between 2.0 and 4.3 mM. Cell growth was restrained with the same efficacy when the ASA treatment was applied to three-dimensional soft-agar cultures. In addition, ASA significantly reduced migration and invasion in two of the three ATC cell lines. We finally investigated the effects of ASA on the MAPK and PI3K/Akt signaling pathways, which are often altered in ATC. The results showed that the phosphorylation status of the Akt1/2/3 kinases was significantly reduced following ASA treatment, while ERK1/2 phosphorylation was either unaffected or slightly upregulated. Conclusions: our findings support epidemiological evidence on the anticancer potential of ASA. On this basis, further investigations should be carried out to assess the usefulness of ASA as adjuvant therapy in patients affected by ATC.

Low prostaglandin-endoperoxide synthase-2 gene expression in colorectal carcinomas may predict poorer survival

Introduction

Prostaglandin-endoperoxide synthase-2 (ptgs2), otherwise called Cyclooxygenase 2, is overexpressed in colorectal carcinoma (CRC) compared to normal tissues. However, the impact of differential expression among ptgs2-positive tumours on CRC prognosis has not been well investigated. By sub-stratifying positive tumour expression, this study determined its potential influence on patients' outcomes.

Methods

The Cancer Genome Atlas database was explored to determine CRC cases with RNA-Sequence (RNA-Seq) transcript data and matched clinicopathological data alongside gene copy number variation and methylation status. Descriptive, chi-square, Fisher exact, Linear-by-Linear associations, logistic and Kaplan-Meier statistics were used to determine proportions, associations, predictors and survival between ptgs2 and tumour parameters using Statistical Package for Social Sciences version 20. Two-tailed p-value <0.05 was accepted as statistically significant.

Results

There were 534 CRC classified predominantly as adenocarcinoma not otherwise specified (86.3%) and mucinous carcinoma (12.4) histologically included in this study. Marker (ptgs2) expression ranged from 0.02 FPKM-131.89 FPKM, (Median 1.4 FPKM). The majority of the cases (53.4%) were diagnosed at an early stage and showed high ptgs2 RNA-Sequence (RNA-seq) expression in 51.5% (275/534). Significant associations were seen between ptgs2 expression and histological subtype (p < 0.001), lymphovascular invasion (p = 0.013), pN2 stage (> 6 positive lymph nodes) (p = 0.011) and American Joint Committee on Cancer Staging stage (p = 0.028), and these all had lower ptgs2 expression. On regression analysis, histological differentiation emerged as a predictor of ptgs2 expression (Odds ratio 2.749, 95% confidence interval 1.479-5.108, p < 0.001). Also, gene methylation was associated with reduced ptgs2 expression. Overall survival was significantly inferior among individuals with low ptgs2 tumours (p = 0.018) while that for disease-free survival was non-significant (p = 0.327).

Conclusion

CRCs with low ptgs2 transcripts are associated with poorer survival. This finding suggests a need for closer follow up and tailored adjuvant therapy for these patients.

Systems Approach to Integrating Preclinical Apolipoprotein E-Knockout Investigations Reveals Novel Etiologic Pathways and Master Atherosclerosis Network in Humans

OBJECTIVE

Animal models of atherosclerosis are used extensively to interrogate molecular mechanisms in serial fashion. We tested whether a novel systems biology approach to integration of preclinical data identifies novel pathways and regulators in human disease. Approach and Results: Of 716 articles published in ATVB from 1995 to 2019 using the apolipoprotein E knockout mouse to study atherosclerosis, data were extracted from 360 unique studies in which a gene was experimentally perturbed to impact plaque size or composition and analyzed using Ingenuity Pathway Analysis software. TREM1 (triggering receptor expressed on myeloid cells) signaling and LXR/RXR (liver X receptor/retinoid X receptor) activation were identified as the top atherosclerosis-associated pathways in mice (both P<1.93×10-4, TREM1 implicated early and LXR/RXR in late atherogenesis). The top upstream regulatory network in mice (sc-58125, a COX2 inhibitor) linked 64.0% of the genes into a single network. The pathways and networks identified in mice were interrogated by testing for associations between the genetically predicted gene expression of each mouse pathway-identified human homolog with clinical atherosclerosis in a cohort of 88 660 human subjects. Homologous human pathways and networks were significantly enriched for gene-atherosclerosis associations (empirical P<0.01 for TREM1 and LXR/RXR pathways and COX2 network). This included 12(60.0%) TREM1 pathway genes, 15(53.6%) LXR/RXR pathway genes, and 67(49.3%) COX2 network genes. Mouse analyses predicted, and human study validated, the strong association of COX2 expression (PTGS2) with increased likelihood of atherosclerosis (odds ratio, 1.68 per SD of genetically predicted gene expression; P=1.07×10-6).

CONCLUSIONS

PRESCIANT (Preclinical Science Integration and Translation) leverages published preclinical investigations to identify high-confidence pathways, networks, and regulators of human disease.

Use of aspirin post-diagnosis in a cohort of patients with colorectal cancer and its association with all-cause and colorectal cancer specific mortality

OBJECTIVE

Aspirin is associated with a reduced risk of developing colorectal cancer. This study examined whether patients with colorectal cancer prescribed aspirin had improved survival.

DESIGN

An observational population cohort study was undertaken using data linkage of cancer registry, dispensed prescriptions and death certificate records in Tayside, Scotland. All community prescribed aspirin pre- and post-diagnosis was extracted and periods of aspirin use post-diagnosis for each individual were analysed using Cox proportional hazard models. Main outcome measures were all-cause and colorectal mortality from death certificates.

RESULTS

Two thousand nine hundred ninety patients were identified with colorectal cancer between 1st January 1997 and 30th December 2006 and followed up until 28th February 2010. Median age at diagnosis was 73 (interquartile range [IQR] 65-80) with 52% male. One thousand nine hundred ninety-eight (67%) deaths were recorded with 1021 (34%) attributed to colorectal cancer. One thousand three hundred forty (45%) patients used aspirin at some stage of the study period. Aspirin use post-diagnosis was associated with lower risk of all cause mortality (hazard ratio [HR]=0.67, 95% confidence interval [CI]=0.57-0.79, p<0.001) and colorectal cancer specific mortality after allowing for age, Dukes' stage, gender, socio-economic status and aspirin use pre-diagnosis. Increasing age and stage at diagnosis were associated with increased risk, with more affluent patients at reduced risk.

CONCLUSIONS

Our study suggests that aspirin use post-diagnosis of colorectal cancer may reduce both all cause and colorectal cancer specific mortality. However further work is required to ensure this is a causal relationship and to identify whether it is best used in specific groups of patients.

Celecoxib and Bcl-2: emerging possibilities for anticancer drug design

Celecoxib is a multifaceted drug with promising anticancer properties. A number of studies have been conducted that implicate the compound in modulating the expression of Bcl-2 family members and mitochondria-mediated apoptosis. The growing data surrounding the role of celecoxib in the regulation of the mitochondrial death pathway provides a platform for ongoing debate. Studies that describe celecoxib's properties as a BH3 mimic or as a direct inhibitor of Bcl-2 are not available. The motivations for this review are: to provide the basis for the development of novel compounds that modulate Bcl-2 expression using celecoxib as a structural starting point and to encourage additional biological studies (such as binding and enzymatic assays) that would provide information regarding celecoxib's role as a Bcl-2 antagonist. The current review summarizes work that identifies the role of celecoxib in blocking the activity of Bcl-2.

Use of aspirin postdiagnosis improves survival for colon cancer patients

Background:

The preventive role of non-steroid anti-inflammatory drugs (NSAIDs) and aspirin, in particular, on colorectal cancer is well established. More recently, it has been suggested that aspirin may also have a therapeutic role. Aim of the present observational population-based study was to assess the therapeutic effect on overall survival of aspirin/NSAIDs as adjuvant treatment used after the diagnosis of colorectal cancer patients.

Methods:

Data concerning prescriptions were obtained from PHARMO record linkage systems and all patients diagnosed with colorectal cancer (1998–2007) were selected from the Eindhoven Cancer Registry (population-based cancer registry). Aspirin/NSAID use was classified as none, prediagnosis and postdiagnosis and only postdiagnosis. Patients were defined as non-user of aspirin/NSAIDs from the date of diagnosis of the colorectal cancer to the date of first use of aspirin or NSAIDs and user from first use to the end of follow-up. Poisson regression was performed with user status as time-varying exposure.

Results:

In total, 1176 (26%) patients were non-users, 2086 (47%) were prediagnosis and postdiagnosis users and 1219 (27%) were only postdiagnosis users (total n=4481). Compared with non-users, a survival gain was observed for aspirin users; the adjusted rate ratio (RR) was 0.77 (95% confidence interval (CI) 0.63–0.95; P=0.015). Stratified for colon and rectal, the survival gain was only present in colon cancer (adjusted RR 0.65 (95%CI 0.50–0.84; P=0.001)). For frequent users survival gain was larger (adjusted RR 0.61 (95%CI 0.46–0.81; P=0.001). In rectal cancer, aspirin use was not associated with survival (adjusted RR 1.10 (95%CI 0.79–1.54; P=0.6). The NSAIDs use was associated with decreased survival (adjusted RR 1.93 (95%CI 1.70–2.20; P<0.001).

Conclusion:

Aspirin use initiated or continued after diagnosis of colon cancer is associated with a lower risk of overall mortality. These findings strongly support initiation of a placebo-controlled trial that investigates the role of aspirin as adjuvant treatment in colon cancer patients.

Identifying inhibitors of epithelial-mesenchymal transition by connectivity map-based systems approach

BACKGROUND

Acquisition of mesenchymal phenotype by epithelial cells by means of epithelial-mesenchymal transition (EMT) is considered as an early event in the multistep process of tumor metastasis. Therefore, inhibition of EMT might be a rational strategy to prevent metastasis.

METHODS

Using the global gene expression profile from a cell culture model of transforming growth factor-β (TGF-β)-induced EMT, we identified potential EMT inhibitors. We used a publicly available database (www.broad.mit.edu/cmap) comprising gene expression profiles obtained from multiple different cell lines in response to various drugs to derive negative correlations to EMT gene expression profile using Connectivity Map, a pattern matching tool.

RESULTS

Experimental validation of the identified compounds showed rapamycin as a novel inhibitor of TGF-β signaling along with 17-AAG, a known modulator of TGF-β pathway. Both of these compounds completely blocked EMT and the associated migratory and invasive phenotype. The other identified compound, LY294002, demonstrated a selective inhibition of mesenchymal markers, cell migration and invasion, without affecting the loss of E-cadherin expression or Smad phosphorylation.

CONCLUSIONS

Our data reveal that rapamycin is a novel modulator of TGF-β signaling, and along with 17-AAG and LY294002, could be used as therapeutic agent for inhibiting EMT. This study demonstrates the potential of a systems approach in identifying novel modulators of a complex biological process.

Genome-wide analyses of gene expression during mouse endochondral ossification

Background

Endochondral ossification is a complex process involving a series of events that are initiated by the establishment of a chondrogenic template and culminate in its replacement through the coordinated activity of osteoblasts, osteoclasts and endothelial cells. Comprehensive analyses of in vivo gene expression profiles during these processes are essential to obtain a complete understanding of the regulatory mechanisms involved.

Methodology/Principal Findings

To address these issues, we completed a microarray screen of three zones derived from manually segmented embryonic mouse tibiae. Classification of genes differentially expressed between each respective zone, functional categorization as well as characterization of gene expression patterns, cytogenetic loci, signaling pathways and functional motifs both confirmed reported data and provided novel insights into endochondral ossification. Parallel comparisons of the microdissected tibiae data set with our previously completed micromass culture screen further corroborated the suitability of micromass cultures for modeling gene expression in chondrocyte development. The micromass culture system demonstrated striking similarities to the in vivo microdissected tibiae screen; however, the micromass system was unable to accurately distinguish gene expression differences in the hypertrophic and mineralized zones of the tibia.

Conclusions/Significance

These studies allow us to better understand gene expression patterns in the growth plate and endochondral bones and provide an important technical resource for comparison of gene expression in diseased or experimentally-manipulated cartilages. Ultimately, this work will help to define the genomic context in which genes are expressed in long bones and to understand physiological and pathological ossification.

Aspirin use and survival after diagnosis of colorectal cancer

CONTEXT

Aspirin reduces risk of colorectal neoplasia in randomized trials and inhibits tumor growth and metastases in animal models. However, the influence of aspirin on survival after diagnosis of colorectal cancer is unknown.

OBJECTIVE

To examine the association between aspirin use after colorectal cancer diagnosis on colorectal cancer-specific and overall survival.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 1279 men and women diagnosed with stage I, II, or III colorectal cancer. Participants were enrolled in 2 nationwide health professional cohorts in 1980 and 1986 prior to diagnosis and followed up through June 1, 2008.

MAIN OUTCOME MEASURE

Colorectal cancer-specific and overall mortality.

RESULTS

After a median follow-up of 11.8 years, there were 193 total deaths (35%) and 81 colorectal cancer-specific deaths (15%) among 549 participants who regularly used aspirin after colorectal cancer diagnosis, compared with 287 total deaths (39%) and 141 colorectal cancer-specific deaths (19%) among 730 participants who did not use aspirin. Compared with nonusers, participants who regularly used aspirin after diagnosis experienced a multivariate hazard ratio (HR) for colorectal cancer-specific mortality of 0.71 (95% confidence interval [CI], 0.53-0.95) and for overall mortality of 0.79 (95% CI, 0.65-0.97). Among 719 participants who did not use aspirin before diagnosis, aspirin use initiated after diagnosis was associated with a multivariate HR for colorectal cancer-specific mortality of 0.53 (95% CI, 0.33-0.86). Among 459 participants with colorectal cancers that were accessible for immunohistochemical assessment, the effect of aspirin differed significantly according to cyclooxygenase 2 (COX-2) expression (P for interaction = .04). Regular aspirin use after diagnosis was associated with a lower risk of colorectal cancer-specific mortality among participants in whom primary tumors overexpressed COX-2 (multivariate HR, 0.39; 95% CI, 0.20-0.76), whereas aspirin use was not associated with lower risk among those with primary tumors with weak or absent expression (multivariate HR, 1.22; 95% CI, 0.36-4.18).

CONCLUSION

Regular aspirin use after the diagnosis of colorectal cancer is associated with lower risk of colorectal cancer-specific and overall mortality, especially among individuals with tumors that overexpress COX-2.

Regulation of cyclooxygenase-2 (COX-2) expression in human pancreatic carcinoma cells by the insulin-like growth factor-I receptor (IGF-IR) system

Both the insulin-like growth factor-I receptor (IGF-IR) and cyclooxygenase-2 (COX-2) are frequently overexpressed in pancreatic cancer. We hypothesized that IGF-IR is directly involved in induction of COX-2 and sought to investigate signaling pathways mediating this effect. Pancreatic cancer cells (L3.6pl) were stably transfected with a dominant-negative receptor (IGF-IR DN) construct or empty vector (pcDNA). Cells were stimulated with IGF-I to determine activated signaling intermediates and induction of COX-2. Signaling pathways mediating COX-2 induction were identified using signaling inhibitors. IGF-I up-regulated COX-2 selectively via the MAPK/(Erk-1/2) pathway. In addition, IGF-IR DN cells showed a marked decrease in constitutive COX-2 and a blunted response to IGF-I. Similarly, treatment with an anti-IGF-IR antibody effectively inhibited IGF-IR and MAPK/Erk activation and decreased COX-2 in parental cells. In conclusion, activation of IGF-IR mediates COX-2 expression in human pancreatic cancer cells.

The effects of a cyclooxygenase-2 (COX-2) expression and inhibition on human uveal melanoma cell proliferation and macrophage nitric oxide production

Background

Cyclooxygenase-2 (COX-2) expression has previously been identified in uveal melanoma although the biological role of COX-2 in this intraocular malignancy has not been elucidated. This study aimed to investigate the effect of a COX-2 inhibitor on the proliferation rate of human uveal melanoma cells, as well as its effect on the cytotoxic response of macrophages.

Methods

Human uveal melanoma cell lines were transfected to constitutively express COX-2 and the proliferative rate of these cells using two different methods, with and without the addition of Amfenac, was measured. Nitric oxide production by macrophages was measured after exposure to melanoma-conditioned medium from both groups of cells as well as with and without Amfenac, the active metabolite of Nepafenac.

Results

Cells transfected to express COX-2 had a higher proliferation rate than those that did not. The addition of Amfenac significantly decreased the proliferation rate of all cell lines. Nitric oxide production by macrophages was inhibited by the addition of melanoma conditioned medium, the addition of Amfenac partially overcame this inhibition.

Conclusion

Amfenac affected both COX-2 transfected and non-transfected uveal melanoma cells in terms of their proliferation rates as well as their suppressive effects on macrophage cytotoxic activity.

Targeting cyclooxygenase-2 and the epidermal growth factor receptor for the prevention and treatment of intestinal cancer

Clinical and animal studies indicate a role for cyclooxygenase-2 (COX-2) and the epidermal growth factor receptor (EGFR) in the development and progression of intestinal polyps and cancers. Although this combination of enzyme inhibition has shown synergy in intestinal polyp and tumor models, the exact mechanism for these effects remains undefined. Therefore, we sought to define the molecular mechanisms through which this process occurs. We observed a significant reduction in the number and size of small intestinal polyps in APC(min+/-) mice treated with either celecoxib (a selective COX-2 inhibitor) or erlotinib (Tarceva, an EGFR inhibitor). However, in combination, there was an overall prevention in the formation of polyps by over 96%. Furthermore, we observed a 70% reduction of colorectal xenograft tumors in mice treated with the combination and microarray analysis revealed genes involved in cell cycle progression were negatively regulated. Although we did not observe significant changes in mRNAs of genes with known apoptotic function, there was a significant increase of apoptosis in tumors from animals treated with the combination. The inhibition of EGFR also induced the down-regulation of COX-2 and further inhibited prostaglandin E2 formation. We observed similar effects on the prevention of intestinal adenomas and reduction of xenograft tumor volume when nonselective COX inhibitors were used in combination with erlotinib. Together, these findings suggest that the inhibition of both COX-2 and EGFR may provide a better therapeutic strategy than either single agent through a combination of decreased cellular proliferation and prostaglandin signaling as well as increased apoptosis.

SNS-032 prevents tumor cell-induced angiogenesis by inhibiting vascular endothelial growth factor

Cell proliferation, migration, and capillary network formation of endothelial cells are the fundamental steps for angiogenesis, which involves the formation of new blood vessels. The purpose of this study is to investigate the effect of a novel aminothiazole SNS-032 on these critical steps for in vitro angiogenesis using a coculture system consisting of human umbilical vein endothelial cells (HUVECs) and human glioblastoma cells (U87MG). SNS-032 is a potent selective inhibitor of cyclin-dependent kinases 2, 7, and 9, and inhibits both transcription and cell cycle. In this study, we examined the proliferation and viability of HUVECs and U87MG cells in the presence of SNS-032 and observed a dose-dependent inhibition of cellular proliferation in both cell lines. SNS-032 inhibited threedimensional capillary network formations of endothelial cells. In a coculture study, SNS-032 completely prevented U87MG cell-mediated capillary formation of HUVECs. This inhibitor also prevented the migration of HUVECs when cultured alone or cocultured with U87MG cells. In addition, SNS-032 significantly prevented the production of vascular endothelial growth factor (VEGF) in both cell lines, whereas SNS-032 was less effective in preventing capillary network formation and migration of endothelial cells when an active recombinant VEGF was added to the medium. In conclusion, SNS-032 prevents in vitro angiogenesis, and this action is attributable to blocking of VEGF.

The anti-invasive activity of cyclooxygenase inhibitors is regulated by the transcription factor ATF3 (activating transcription factor 3)

We previously showed that nonsteroidal anti-inflammatory drugs (NSAID) such as sulindac sulfide, which has chemopreventive activity, modulate the expression of several genes detected by microarray analysis. Activating transcription factor 3 (ATF3) was selected for further study because it is a transcription factor involved in cell proliferation, apoptosis, and invasion, and its expression is repressed in human colorectal tumors as compared with normal adjacent tissue. In this report, we show that ATF3 mRNA and protein expression are up-regulated in HCT-116 human colorectal cancer cells following treatment with NSAIDs, troglitazone, diallyl disulfide, and resveratrol. To ascertain the biological significance of ATF3, we overexpressed full-length ATF3 protein in the sense and antisense orientations. Overexpression of ATF3 in the sense orientation decreased focus formation in vitro and reduced the size of mouse tumor xenografts by 54% in vivo. Conversely, overexpression of antisense ATF3 was protumorigenic in vitro, however, not in vivo. ATF3 in the sense orientation did not modulate apoptosis, indicating another mechanism is involved. With microarray analysis, several genes relating to invasion and metastasis were identified by ATF3 overexpression and were confirmed by real-time reverse transcription-PCR, and several of these genes were modulated by sulindac sulfide, which inhibited invasion in these cells. Furthermore, overexpression of ATF3 inhibited invasion to a similar degree as sulindac sulfide treatment, whereas antisense ATF3 increased invasion. In conclusion, ATF3 represents a novel mechanism in which NSAIDs exert their anti-invasive activity, thereby linking ATF3 and its gene regulatory activity to the biological activity of these compounds.

Inhibitory effects of Celecoxib and Sc-58125 on proliferation of human carcinoma of larynx Hep-2 in vitro

The inhibitory effects of two kinds of selective cyclooxygenase-2 inhibitors on the proliferation of human carcinoma of larynx Hep-2 in vitro and their corresponding mechanisms were investigated. Hep-2 cells were cultured with two kinds of selective cyclooxygenase-2 inhibitors (Sc-58125 and Celecoxib) at various concentrations for 24 h. Morphological changes were observed under the phase microscopy and the growth suppression was detected by using MTT colorimetric assay. Apoptotic DNA fragments were observed by agarose gel electrophoresis, and the cell cycle and apoptotic rate were detected by flow cytometry (FCM) respectively. Hep-2 cells became rounded and detached from the culture dish after being treated with Celecoxib for 24 h, however, they remained morphologically unchanged with Sc-58125. Sc-58125 could increase G2 phase cells, whereas, Celecoxib rose G1 phase cells. Both of the two effects were dose-dependent. Moreover, the Hep-2 cells cultured with 50 micromol/L and 100 micromol/L Celecoxib showed obvious apoptosis, with the nuclear DNA of cells exhibiting characteristic DNA ladder. So Sc-58125 could inhibit the proliferation of Hep-2 cells by altering the G2 phase cells. However, Celecoxib had the same effect by changing the G1 phase cells and inducing apoptosis at higher concentration.

Nimesulide, a COX-2 inhibitor, does not reduce lesion size or number in a nude mouse model of endometriosis

BACKGROUND

Women with endometriosis have elevated levels of cyclooxygenase-2 (COX-2) in peritoneal macrophages and endometriotic tissue. Inhibition of COX-2 has been shown to reduce inflammation, angiogenesis and cellular proliferation. It may also downregulate aromatase activity in ectopic endometrial lesions. Ectopic endometrial establishment and growth are therefore likely to be suppressed in the presence of COX-2 inhibitors. We hypothesized that COX-2 inhibition would reduce the size and number of ectopic human endometrial lesions in a nude mouse model of endometriosis.

METHODS

The selective COX-2 inhibitor, nimesulide, was administered to estrogen-supplemented nude mice implanted with human endometrial tissue. Ten days after implantation, the number and size of ectopic endometrial lesions were evaluated and compared with lesions from a control group. Immunohistochemical assessment of vascular development and macrophage and myofibroblast infiltration in control and treated lesions was performed.

RESULTS

There was no difference in the number or size of ectopic endometrial lesions in control and nimesulide-treated nude mice. Nimesulide did not induce a visually identifiable difference in blood vessel development or macrophage or myofibroblast infiltration in nude mouse explants.

CONCLUSION

The hypothesized biological properties of COX-2 inhibition did not influence lesion number or size in the nude mouse model of endometriosis.

Up-regulation of the enzymes involved in prostacyclin synthesis via Ras induces vascular endothelial growth factor

BACKGROUND AND AIMS

The constitutive activation of Ras is an important step in the development and progression of several different cancers and is known to increase the level of cyclooxygenase 2 (COX-2). Prostaglandins are the downstream bioactive lipid mediators produced by the COX-2 enzyme. We sought to determine the role of Ras-induced up-regulation of the enzymes involved in prostacyclin biosynthesis in nontransformed rat intestinal epithelial cells (IECs).

METHODS

Messenger RNA (mRNA) and protein expression were analyzed by Northern and Western analysis, respectively, to determine the level of enzymes induced by Ras. In vitro assays were used to determine the production of vascular endothelial growth factor (VEGF) and prostaglandins as well as the promoter and enzymatic activation of the rate-limiting enzyme in prostaglandin production (phospholipase A(2) [cPLA(2)]).

RESULTS

The inducible expression of Ha-Ras(V12) increased the production of prostaglandin (PG)F(2alpha) and prostacyclin by 2- and 13-fold, respectively. The induction of Ha-Ras(V12) also up-regulated the mRNA and protein levels of cPLA(2), COX-2, and prostacyclin synthase, as well as the promoter and enzyme activity of cPLA(2). Furthermore, oncogenic Ras increased the production of the pro-angiogenic factor VEGF. The increase of VEGF was abolished after treatment with celecoxib, a selective COX-2 inhibitor. The addition of PGI 2 alone also induced the expression of VEGF.

CONCLUSIONS

Inducible Ha-Ras(V12) increases the production of PGI(2) through the coordinate up-regulation of cPLA(2), COX-2, and prostacyclin synthase (PGIS). The production of PGI(2) leads to an increase in the level of the pro-angiogenic factor VEGF, which is known to play a crucial role in the regulation of tumor-associated angiogenesis.

Sequence-dependent effect of a cyclooxygenase-2 inhibitor on topoisomerase I inhibitor and 5-fluorouracil-induced cytotoxicity of colon cancer cells

Selective cyclooxygenase-2 (COX-2) inhibitors have been found to induce anti-proliferative and apoptotic activity in many cancer cells. However, interaction between COX-2 inhibitors and other chemotherapeutic agents remains to be determined. We investigated the interactive effects of a selective COX-2 inhibitor, etodolac, in combination with 5-fluorouracil (5-FU) or SN-38 (active metabolite of irinotecan) on colon cancer cell lines, HT29 and SW620, in simultaneous and sequential administration schedules. Isobologram analysis demonstrated that etodolac in combination with 5-FU or SN-38 according to a simultaneous schedule resulted in only an additive effect; however, synergism was achieved in a sequential schedule. Apoptosis induction in both cell lines was also significantly increased after sequential treatment with etodolac followed by either 5-FU or SN-38 compared to that after simultaneous treatment with etodolac and either 5-FU or SN-38. Our study suggests apoptosis-inducing synergism resulted from administration of etodolac and either 5-FU or SN-38 sequentially, but not simultaneously.

Anti-angiogenic therapy in breast cancer

Breast cancer is a worldwide epidemic among women, and one of the most rapidly increasing cancers. Not only the incidence rate but also the death rate is increasing. Despite enthusiastic efforts in early diagnosis, aggressive surgical treatment and application of additional non-operative modalities, its prognosis is still dismal. This emphasizes the necessity to develop new measures and strategies for its prevention. The understanding of the biology of angiogenesis is improving rapidly, offering the hope for more specific vascular targeting of tumor neovasculature. Anti-angiogenic therapy is a promising, relatively new form of cancer treatment using drugs called angiogenesis inhibitors that specifically inhibit new blood vessel growth. Extensive studies conducted over the past few years have recognized that overexpression of COX-2, VEGF in the cancer might be the leading factors, can induce angiogenesis via induction of multiple pro-angiogenic regulators. Breast tumor growth and metastasization are both hormone-sensitive and angiogenesis-dependent. A single angiogenic inhibitor is not capable to inhibit angiogenesis. Therefore, we should select a combination of angiogenesis inhibitors targeting COX-2, VEGF, and bFGF pathway. This article reviews the background and implementation of the current use of angiogenesis inhibitors and discusses the likely therapeutic roles in the early and advanced breast cancer together with its potential for chemoprevention.

COX inhibitors modulate bFGF-induced cell survival in MCF-7 breast cancer cells

Basic fibroblast growth factor (bFGF) serves as a modulator of survival in breast cancer cells. The mechanisms by which bFGF transduces the anti-apoptotic signal and interacts with COX inhibitors were investigated. bFGF reduced apoptosis in MCF-7 breast cancer cells and up-regulated the expression of mitocondrial Bcl-2, whereas COX inhibitors meloxicam (selective COX-2) and aspirin (non-selective), induced apoptosis. bFGF up-regulated survivin protein expression and induced cdc-2 phosphorylation moderately at early (2-6 h), and substantially at late (24 h), time-points. Survivin mRNA expression was up-regulated only at the later time-point. COX inhibitors prevented up-regulation of survivin protein expression at both 2 and 24 h and prevented early modest increases in cdc-2 phosphorylation. Up-regulation of survivin mRNA was not found to be modulated by the COX-2 inhibitor meloxicam. bFGF regulation of survivin expression was found to be ERK1/2 kinase dependent and bFGF-induced phosphorylation of c-raf was prevented by the COX-2 inhibitor. bFGF was, however, unable to induce COX-2 protein expression or modulate COX-2 activity in MCF-7 cells as evidenced by unaltered PGE(2) production. These results indicate that bFGF regulates survivin expression in MCF-7 breast cancer cells by signaling through an ERK1/2 dependent pathway. COX-2 inhibitors can modulate bFGF-induced survivin expression in a COX-2 independent manner.

Prostaglandin E2 regulates cell migration via the intracellular activation of the epidermal growth factor receptor

Over the past decade cyclooxygenase-2-derived prostaglandins have been implicated in the development and progression of many types of cancer. Recently our laboratory has shown that treatment with prostaglandin E2 (PGE2) induces increased proliferation, migration, and invasiveness of colorectal carcinoma cells (Sheng, H., Shao, J., Washington, M. K., and DuBois, R. N. (2001) J. Biol. Chem. 276, 18075-18081). The stimulatory effects of PGE2 were dependent upon the activation of the phosphatidylinositol 3-kinase/Akt pathway. However, the exact signaling cascade responsible for phosphatidylinositol 3-kinase/Akt activation by PGE2 remains poorly defined. In the present study, we demonstrate that the PGE2-induced migration and invasion occurs via rapid transactivation and phosphorylation of the epidermal growth factor receptor (EGFR). Within minutes following treatment, PGE2 induces the activation of Akt. This effect was completely abolished by EGFR-specific tyrosine kinase inhibitors providing evidence for the role of the EGFR in this response. The rapid transactivation of the EGFR occurs via an intracellular Src-mediated event but not through the release of an extracellular epidermal growth factor-like ligand. EGFR transactivation was also observed in vivo by the direct comparison of normal and malignant human colorectal samples. These results suggest that in developing colonic carcinomas, the early effects of cyclooxygenase-2-derived PGE2 are in part mediated by the EGFR, and this transactivation is responsible for subsequent down-stream effects including the stimulation of cell migration and invasion.

Combined-modality treatment of solid tumors using radiotherapy and molecular targeted agents

PURPOSE

Molecular targeted agents have been combined with radiotherapy (RT) in recent clinical trials in an effort to optimize the therapeutic index of RT. The appeal of this strategy lies in their potential target specificity and clinically acceptable toxicity.

DESIGN

This article integrates the salient, published research findings into the underlying molecular mechanisms, preclinical efficacy, and clinical applicability of combining RT with molecular targeted agents. These agents include inhibitors of intracellular signal transduction molecules, modulators of apoptosis, inhibitors of cell cycle checkpoints control, antiangiogenic agents, and cyclo-oxygenase-2 inhibitors.

RESULTS

Molecular targeted agents can have direct effects on the cytoprotective and cytotoxic pathways implicated in the cellular response to ionizing radiation (IR). These pathways involve cellular proliferation, DNA repair, cell cycle progression, nuclear transcription, tumor angiogenesis, and prostanoid-associated inflammation. These pathways can also converge to alter RT-induced apoptosis, terminal growth arrest, and reproductive cell death. Pharmacologic modulation of these pathways may potentially enhance tumor response to RT though inhibition of tumor repopulation, improvement of tumor oxygenation, redistribution during the cell cycle, and alteration of intrinsic tumor radiosensitivity.

CONCLUSION

Combining RT and molecular targeted agents is a rational approach in the treatment of solid tumors. Translation of this approach from promising preclinical data to clinical trials is actively underway.

Non steroidal anti-inflammatory drugs and COX-2 inhibitors as anti-cancer therapeutics: hypes, hopes and reality

Non-steroidal anti-inflammatory drugs (NSAIDs) and specific inhibitors of cyclooxygenase (COX)-2, are therapeutic groups widely used for the treatment of pain, inflammation and fever. There is growing experimental and clinical evidence indicating NSAIDs and COX-2 inhibitors also have anti-cancer activity. Epidemiological studies have shown that regular use of Aspirin and other NSAIDs reduces the risk of developing cancer, in particular of the colon. Molecular pathology studies have revealed that COX-2 is expressed by cancer cells and cells of the tumor stroma during tumor progression and in response to chemotherapy or radiotherapy. Experimental studies have demonstrated that COX-2 over expression promotes tumorigenesis, and that NSAIDs and COX-2 inhibitors suppress tumorigenesis and tumor progression. Clinical trials have shown that NSAIDs and COX-2 inhibitors suppress colon polyp formation and malignant progression in patients with familial adenomatous polyposis (FAP) syndrome. Recent advances in the understanding of the cellular and molecular mechanisms of the anti-cancer effects of NSAIDs and COX-2 inhibitors have demonstrated that these drugs target both tumor cells and the tumor vasculature. The therapeutic benefits of COX-2 inhibitors in the treatment of human cancer in combination with chemotherapy or radiotherapy are currently being tested in clinical trials. In this article we will review recent advances in the understanding of the anti-tumor mechanisms of these drugs and discuss their potential application in clinical oncology.