Gene modulation by Cox-1 and Cox-2 specific inhibitors in human colorectal carcinoma cancer cells

Abstract

Cox-1 and Cox-2 specific inhibitors exert chemo-preventative activity. However, the exact mechanisms for this activity remain unclear. Increasing evidence suggests that non-steroidal anti-inflammatory drugs regulate gene expression, which may be responsible, in part, for this activity. In this study, human colorectal carcinoma HCT-116 cells were treated with the Cox-1 specific inhibitor SC-560 and the Cox-2 specific inhibitor SC-58125 to evaluate their ability to induce apoptosis, inhibit cell proliferation, inhibit growth on soft agar and modulate gene expression. The Cox-1 specific inhibitor, SC-560 significantly induced apoptosis and inhibited the growth of HCT-116 cells on soft agar, an in vitro assay for tumorigenicity. SC-58125 moderately induced apoptosis and inhibited growth on soft agar at higher concentrations than were required for SC-560. Previously, we reported that the potent chemo-preventative drug sulindac sulfide altered the expression of eight genes including several transcription factors that may be linked to this drug's chemo-preventative activity. HCT-116 cells were treated with various concentrations of SC-560 or SC-58125 and changes in the expression of these eight genes were determined by real-time reverse transcription- polymerase chain reaction. SC-560 modulated mRNA expression of the eight genes studied. In contrast, SC-58125 required approximately 5-10-fold higher concentrations to achieve similar degrees of gene modulation in six of eight genes. Changes in protein expression by SC-560 also occurred for five of these genes with antibodies available (NAG-1, ATF3, C/EBPbeta, MAD2 and MSX1). In conclusion, this is the first report to suggest that like sulindac sulfide, the Cox-1 specific inhibitor SC-560 appears to elicit chemo-preventative activity by altering gene expression, while the chemo-preventative effects of SC-58125 are complex and probably work through these and other mechanisms, such as the inhibition of Cox-2.

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

“…3). SC-58125 did not induce ATF3 in the highly malignant U87MG cell line as has been reported in SW-480 cells (38).…”

“…This was confirmed by Northern blot analysis and correlated with the levels of induction (data not shown and ref. 38). Induction of ATF3 mRNA was time dependent with maximal induction occurring around 4 hours, preceding the induction of ATF3 protein.…”

“…One gene, ATF3, was considered for further study because it is a transcription factor involved in cell proliferation, apoptosis, and invasion, and its expression is down-regulated in colorectal tumors (29). ATF3 expression is modulated by a wide variety of compounds including NSAIDs (29,38), genotoxic agents (ionizing radiation, UV radiation, and methyl methanesulfonate; ref. 42), peroxisome proliferator-activated receptor ligands (43), dietary compounds with cytotoxic activity and documented anticancer properties (34,44), anticancer drugs (35,36), and growth factors (45,46).…”

“…Mice were housed and treated according to the National Institute of Environmental Health Sciences Animal Care and Use Committee. On day 1, PBS or stable pools of actively growing vector, antisense, and sense HCT-116 cells (3 Â 10 6 cells) were injected s.c. in a final volume of 0.1 mL PBS behind the right forelimb of each mouse (19.3 F 0.47 g) as previously reported by our laboratory (38). Measurement of the resulting tumor xenografts began when the size was more than 2 mm in diameter (f50 mm 3 ) and proceeded until the animals were sacrificed at the end of the study.…”

Cyclooxygenase Isozymes in Oral Squamous Cell Carcinoma: A Real-Time RT-PCR Study with Clinic Pathological Correlations

“…Moreover, in a most recent review on the immunosuppressive role of COX-inhibitors on tumor cells, Lang et al (12) stated that high expression levels of at least one of the two COX enzyme are detectable in human cancers. Taken together, such data seem to suggest that this enzyme, which has long been considered the constitutive isoform of cyclooxygenase, physiologically expressed in normal tissues, may play a more relevant role in the development of tumors than expected, most likely by modulating gene expression and promoting neo-angiogenesis via autocrine/paracrine regulation of vascular growth factors (13)(14). A significant inverse relationship was found between the two cyclooxygenase isoforms, which to our knowledge has never been reported in literature (Fig.…”