JTE-522, a selective COX-2 inhibitor, inhibits growth of pulmonary metastases of colorectal cancer in rats

Inhibition of cancer migration and invasion by knocking down delta-5-desaturase in COX-2 overexpressed cancer cells

We recently reported that knockdown of delta-5-desaturase (a key enzyme that converts dihomo-γ-linolenic acid, DGLA, to the downstream ω-6 arachidonic acid) promotes formation of an anti-cancer byproduct 8-hydroxyoctanoic acid from cyclooxygenase (COX)-catalyzed DGLA peroxidation. 8-hydroxyoctanoic acid can exert its growth inhibitory effect on cancer cells (e.g. colon and pancreatic cancer) by serving as a histone deacetylase inhibitor. Since histone deacetylase inhibitors have been well-known to suppress cancer cell migration and invasion, we thus tested whether knockdown of delta-5-desaturase and DGLA treatment could also be used to inhibit cancer migration and invasion of colon cancer and pancreatic cancer cells. Wound healing assay, transwell assay and western blot were used to assess cell migration and invasion as well as the associated molecular mechanisms. Formation of threshold level of 8-hydroxyoctanoic acid was quantified from COX-catalyzed DGLA peroxidation in the cancer cells that overexpress COX-2 and their delta-5-desaturases were knocked down by shRNA transfection. Our results showed that knockdown of delta-5-desaturase along with DGLA supplement not only significantly inhibited cell migration, but also improved the efficacies of 5-flurouracil and gemcitabine, two frontline chemotherapy drugs currently used in the treatment of colon and pancreatic cancer, respectively. The molecular mechanism behind these observations is that 8-hydroxyoctanoic acid inhibits histone deacetylase, resulting in downregulation of cancer metastasis promotors, e.g., MMP-2 and MMP-9 as well as upregulation of cancer metastasis suppressor, e.g. E-cadherin. For the first time, we demonstrated that we could take the advantage of the common phenomenon of COX-2 overexpression in cancers to inhibit cancer cell migration and invasion. With the shifting paradigm of COX-2 cancer biology, our research outcome may provide us a novel cancer treatment strategy.

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High level of COX-2 could be used to inhibit cancer cell migration and invasion.

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8-hydroxyoctanoic acid suppresses cancer migration and invasion via inhibiting HDAC.

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D5D knockdown and DGLA improves efficacy of chemotherapy to inhibit cancer metastasis.

Ketoprofen in topical formulation decreases the matrix metalloproteinase-2 expression and pulmonary metastatic incidence in nude mice with osteosarcoma

The aim of this study was to investigate whether ketoprofen (KP) in topical formulation affected the tumor growth and pulmonary metastasis of LM8 cells, which were inoculated subcutaneously into the back space of male nude mice. At 7 days after inoculation, the tumor was treated topically for 3 weeks with either a KP-containing patch (KP group) or a placebo-containing patch (placebo group). The pulmonary metastatic incidence was 100% in the placebo group and 60% in the KP group. The tumor mass of the KP group without pulmonary metastasis, termed the KP/metastasis(-) group, was smaller than that of the placebo group. Immunohistochemical staining for proliferating cell nuclear antigen (PCNA), terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), matrix metalloproteinase-2 (MMP-2), and vascular endothelial growth factor (VEGF) was performed. The tumors of the KP/metastasis(-) group contained fewer PCNA-positive cells and many more TUNEL-positive cells in comparison to the placebo group. In the placebo group, MMP-2 and VEGF were extensively expressed within the tumor, whereas in the KP/metastasis(-) group the expression of these two proteins was very low. In conclusion, the topical treatment of osteosarcoma with KP decreased the expression of MMP-2 and VEGF, thus resulting in the suppression of tumor growth and pulmonary metastasis.

Absence of cyclooxygenase-2 protein expression is a predictor of tumor regression in rectal cancer treated with preoperative short-term chemoradiotherapy

PURPOSE

Neoadjuvant chemoradiotherapy followed by total mesorectal excision has become the standard of care for patients with locally advanced rectal cancer. This study was designed to determine whether pretreatment cyclooxygenase-2 and p53 protein expression were predictors of histopathologic response in patients with rectal cancer treated with preoperative short-term chemoradiotherapy.

METHODS

Fifty-two patients with low rectal cancer received short-term preoperative chemoradiotherapy (20 Gy given in 5 daily doses of 4 Gy and concurrent administration of Tegafur/Uracil 400 mg/day), followed by total mesorectal excision. Cyclooxygenase-2 and p53 protein expression were measured by immunohistochemistry before and at the time of resection. Tumor regression grading was evaluated according to the criteria by Rodel (Grade 4, complete regression; Grade 3, regression >50 percent; Grade 2, 25-50 percent; Grade 1,<25 percent; and Grade 0, no regression).

RESULTS

Two patients had a pathologic complete response. Good response (Grade 3 + 4) was found in 57.7 percent of the resected specimens. Cyclooxygenase-2 was expressed in 80.8 percent of patients before chemoradiotherapy and in 100 percent after chemoradiotherapy. The rates of good response (Grade 3 + 4) were significantly associated with lack of cyclooxygenase-2 expression before chemoradiotherapy (P = 0.021). However, there was no correlation between p53 protein expression and tumor regression grading.

CONCLUSIONS

Patients with tumor lacking cyclooxygenase-2 expression before chemoradiotherapy are more likely to demonstrate good response to treatment. Cyclooxygenase-2 protein expression may be a marker for response to chemoradiotherapy in patients with rectal cancer.

Induction of lung lesions in Wistar rats by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and its inhibition by aspirin and phenethyl isothiocyanate

Background

The development of effective chemopreventive agents against cigarette smoke-induced lung cancer could be greatly facilitated by suitable laboratory animal models, such as animals treated with the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In the current study, we established a novel lung cancer model in Wistar rats treated with NNK. Using this model, we assessed the effects of two chemopreventive agents, aspirin and phenethyl isothiocyanate (PEITC), on tumor progression.

Methods

First, rats were treated with a single-dose of NNK by intratracheal instillation; control rats received iodized oil. The animals were then sacrificed on the indicated day after drug administration and examined for tumors in the target organs. PCNA, p63 and COX-2 expression were analyzed in the preneoplastic lung lesions. Second, rats were treated with a single-dose of NNK (25 mg/kg body weight) in the absence or presence of aspirin and/or PEITC in the daily diet. The control group received only the vehicle in the regular diet. The animals were sacrificed on day 91 after bronchial instillation of NNK. Lungs were collected and processed for histopathological and immunohistochemical assays.

Results

NNK induced preneoplastic lesions in lungs, including 33.3% alveolar hyperplasia and 55.6% alveolar atypical dysplasia. COX-2 expression increased similarly in alveolar hyperplasia and alveolar atypical dysplasia, while PCNA expression increased more significantly in the latter than the former. No p63 expression was detected in the preneoplastic lesions. In the second study, the incidences of alveolar atypical dysplasia were reduced to 10%, 10% and 0%, respectively, in the aspirin, PEITC and aspirin and PEITC groups, compared with 62.5% in the carcinogen-treated control group. COX-2 expression decreased after dietary aspirin or aspirin and PEITC treatment. PCNA expression was significantly reduced in the aspirin and PEITC group.

Conclusion

(1) A single dose of 25 mg/kg body weight NNK by intratracheal instillation is sufficient to induce preneoplastic lesions in Wistar rat lungs. (2) COX-2 takes part in NNK-induced tumorigenesis but is not involved in proliferation. (3) Aspirin and PEITC have protective effects in the early stages of tumor progression initiated by NNK.

In vivo observation of pulmonary micrometastasis of colon cancer in normal rats

The initial kinetics of cancer cell metastasis to organs requires investigation to establish an effective strategy against malignant disease. In vivo observation of pulmonary micrometastasis at an extremely early stage is of particular importance, and it is desirable from a clinical perspective to use an animal model with a normal immune system. RCN-9 cells labeled with green fluorescent protein were injected into the liver parenchyma of Fischer F344 male rats and the lungs were observed using real-time confocal laser scanning microscopy from 3 to 10 weeks after injection. Metastasis at the single cell level was observed throughout this period, but the number of pulmonary micrometastases did not increase significantly with time. The largest metastasis was 300 mum in diameter, and the mean size of the metastases did not increase with time. There were two types of micrometastases in terms of shape: round and linear metastases, with the latter resembling the pulmonary microvasculature. The precise location of each pulmonary micrometastasis was revealed by acridine orange infusion. We could observe a single cancer cell and a small cancer mass in endothelial and interstitial locations in vivo, and we found proliferating cancer cells both inside and outside of microvessels. Most of the pulmonary micrometastases stayed dormant as a single cell or a cancer mass of less than 100 microm in diameter until 10 weeks after cancer-cell injection into the liver.

Signal transduction cross-talk during colorectal tumorigenesis

Colorectal carcinoma (CRC) is the second leading cause of cancer-related death in the United States in the general population (men and women combined). Epidemiologic data obtained over the last several decades shows convincing evidence for the efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) in the reduction of risk of CRC through the inhibition of cycloxygenase (COX). Recent research has also demonstrated that prostaglandin E2 (PGE2), a predominant product of COX, plays a critical role in tumorigenesis of CRCs through its guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs), EP2, and EP4. Molecular analysis of CRC and its precursor lesions have shown that mutation of Adenomatous Polyposis Coli (APC), a gene involved in the wingless type signaling pathway, is an early event during the neoplastic progression in the majority of sporadic CRCs. The fundamental questions are: why is wild type APC so important in adult colorectal tissues in preventing this tumorigenesis, and what are the mechanisms by which NSAIDs prevent colorectal tumorigenesis? We reviewed the recent literature concerning the PGE2-GPCR signaling pathway and the APC-beta-catenin (wingless type) pathway in CRC cells and propose a unifying schema regarding the tumorigenesis of CRC. Colorectal epithelia are continuously exposed to various extracellular agonists (including low levels of PGE2). The binding of these agonists to their corresponding GPCRs leads to formation of activated Galphas, which in turn activates beta-catenin. In normal colorectal epithelia, wild type APC blocks the Galphas-induced activation of beta-catenin, and therefore maintains homeostasis and prevents tumorigenesis. In contrast, in the absence of functional APC, continuous formation of activated Galphas by the binding of various extracellular agonists to their receptors leads to the activation and nuclear accumulation of beta-catenin. This elevated nuclear beta-catenin in turn increases transcription of many genes (COX-2, C-myc, Cyclin D1, vascular endothelial growth factor, T cell factor, etc.) involved in tumorigenesis. Increased transcription of COX-2 also leads to excessive production of PGE2 that in turn forms a stimulatory loop with many biologic functions (proliferation, migration, invasion, angiogenesis, and inhibition of apoptosis), which may result in the development of CRC. Because NSAIDs inhibit COX and decrease the production of PGE2, interruption of the cycle helps prevent colorectal tumorigenesis.