Indomethacin suppresses the growth of colon 26, Meth-A and FM3A tumors in mice by reducing the prostaglandin E2 content and telomerase activity in tumor tissues

Regulation of telomerase activity by apparently opposing elements

Telomeres, the ends of chromosomes, undergo frequent remodeling events that are important in cell development, proliferation and differentiation, and neoplastic immortalization. It is not known how the cellular environment influences telomere remodeling, stability, and lengthening or shortening. Telomerase is a ribonucleoprotein complex that maintains and lengthens telomeres in the majority of cancers. Recent studies indicate that a number of factors, including hormones, cytokines, ligands of nuclear receptor, vitamins and herbal extracts have significantly influence telomerase activity and, in some instances, the remodeling of telomeres. This review summarizes the advances in understanding of the positive and negative regulation by extracellular factors of telomerase activity in cancer, stem cells and other systems in mammals.

Cyclooxygenase inhibition in early onset of tumor growth and related angiogenesis evaluated in EP1 and EP3 knockout tumor-bearing mice

It is well established that prostanoids are essential for local inflammation including cell proliferation and apoptosis. Accordingly, prostaglandin E2 (PGE(2)) is a critical factor in wound healing, tumor invasiveness and progression. Therefore, the aim of the present work was to evaluate effects by PGE(2) on tumor vascular density at early onset of tumor growth where hypoxia is limited. Wild-type mice (C57Bl, C3H/HeN) bearing either MCG-101 tumors or a malignant melanoma (K1735-M2) with either high or insignificant PGE(2) production and subsequently different in sensitivity to cyclooxygenase (COX) inhibition were used. Tumor angiogenesis was estimated by intravital microscopy and immune histochemical analysis in wild type and EP(1) or EP(3) subtype receptor knockout mice (C57Bl). Both MCG-101 and K1735-M2 tumor cells stimulated early outgrowth of tumor vessels in proportion to intrinsic growth rate of tumor cells. Indomethacin had no effects on tumor growth or tumor related vascular area in K1735-M2 bearing mice. By contrast, indomethacin decreased tumor cell proliferation and increased apoptosis in MCG-101 tumors with subsequent adaptation in tumor vascular density. Effects of indomethacin on early growth of MCG-101 tumors were not related to tumor content of bFGF protein, while our earlier studies on long-term tumor growth have shown decreased mRNA levels of bFGF during indomethacin treatment. Early onset of tumor growth was significantly promoted in EP(3)- but not in EP(1)-knockouts, although long-term tumor growth is attenuated in EP(1)-knockouts as reported elsewhere. Our results demonstrate that tumor production of PGE(2) promotes primarily net growth of tumor cells with subsequent adaptations in development of the tumor vasculature. Therefore, it is likely that angiogenesis is not a limiting step at the early onset of tumor growth.

Effect of indomethacin on induction of apoptosis in colonic cancer cell line SW480 transferred by wild-type p53 gene

AIM

To investigate the anti-tumor effect of indomethacin on colon cancer.

METHODS

SW480 cells were transferred by wtp53 gene, treated with different concentrations of indomethacin. Apoptosis was analyzed by acridine orange and ethidium bromide staining, and electron microscopy. Expressions of Bcl-2, Bax and p21WAF1/CIPI protein were detected by Western blotting.

RESULTS

Indomethacin induced apoptosis in wtp53/SW480 cells. Typical cell morphological changes included cytoplasm and nuclear shrinkage, nuclear fragmentation and formation of apoptotic bodies. The count of apoptotic cells was dose and time-dependent, and the apoptotic cells accounted for 5.0±2.0% in SW480 cells, 60.1±2.0% in wtp53/SW480 cells treated with 600 μmol/L indomethacin for 72 h (P<0.01), with a significant difference between the two groups. The expression of Bcl-2 protein of wtp53/SW480 cells was down-regulated by indomethacin in a dose dependent manner. The expression of Bax protein did not change, and the expressions of Bcl-2 and Bax protein of SW480 cells did not change either. The expression of p21^WAF1/CIPI protein of wtp53/SW480 cells was up-regulated, reaching the maximal level at the concentration of 400 μmol/L indomethacin and returning to control level at the concentration of 600 μmol/L indomethacin

CONCLUSION

Indomethacin could induce apoptosis in wtp53/SW480 cells by down-regulating the expression of Bcl-2 protein and up-regulating the expression of p21^WAF1/CIPI protein, but no change in Bax protein.

Aspirin and indomethacin exhibit antiproliferative effects and induce apoptosis in T98G human glioblastoma cells

The in vitro antiproliferative and apoptosis inducing properties of the nonsteroidal anti-inflammatory drugs (NSAIDs) like acetyl salicylic acid (aspirin) and indomethacin were investigated in T98G human glioblastoma cells to explore their potential role in the chemoprevention of human glioma. The biological effects induced by aspirin and indomethacin on T98G cells, in which the expression of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) were confirmed by RT-PCR and immunostaining, were investigated by studying cell proliferation and apoptosis assays. The antiproliferative effects occurred in a dose- and time-dependent manner on T98G cells by the treatment with 0.1 -2 mM aspirin and 25-100 microM indomethacin. Moreover, aspirin displayed the greatest growth inhibition within 24 h. Approximately 90% growth inhibition occurred following treatment either with 2 mM aspirin or 100 microM indomethacin by 72 h and induction of apoptosis was confirmed by DNA laddering and TUNEL assay. Our in vitro findings indicate that aspirin and indomethacin have an antiproliferative effect on T98G human glioblastoma cells at toxic concentrations.

Different tumors in bone each give rise to a distinct pattern of skeletal destruction, bone cancer-related pain behaviors and neurochemical changes in the central nervous system

Pain is the most common presenting symptom in patients with bone cancer and bone cancer pain can be both debilitating and difficult to control fully. To begin to understand the mechanisms involved in the generation and maintenance of bone cancer pain, we implanted 3 well-described murine tumor cell lines, 2472 sarcoma, B16 melanoma and C26 colon adenocarcinoma into the femur of immunocompromised C3H-SCID mice. Although each of the tumor cell lines proliferated and completely filled the intramedullary space of the femur within 3 weeks, the location and extent of bone destruction, the type and severity of the pain behaviors and the neurochemical reorganization of the spinal cord was unique to each tumor cell line injected. These data suggest that bone cancer pain is not caused by a single factor such as increased pressure induced by intramedullary tumor growth, but rather that multiple factors are involved in generating and maintaining bone cancer pain.

Telomerase activity is not altered by regular strenuous exercise in skeletal muscle or by sarcoma in liver of rats

Telomerase is a specialized ribonucleoprotein enzyme complex which prevents the loss of the telomere. The activity of telomerase can be up- and down-regulated by various oxidative stresses but the effect of physical exercise is not known, whereas the modifying effect of cancer on telomerase activity is well documented. In the first study, we investigated the effect of mild and strenuous exercise training on telomerase activity, assessed by a PCR ELISA kit. No alteration in telomerase activity was detected. In the second investigation, solid sarcoma cells were transplanted to control, exercise trained or exercise trained and still exercising mice. On the 16th day after the transplantation, the size of tumors in the exercise trained group was 72% and in the exercising group 57% (P < 0.05) of that in the controls. Telomerase activity and 8-hydroxy-2'-deoxyguanosine levels in the liver were not significantly altered by exercise and/or sarcoma. We conclude that mild and strenuous exercise training does not significantly affect the activity of telomerase in the systems studied. Exercise training during sarcoma significantly retards the development of tumors and could possibly serve as a positive adjunct to treatment.

Biochemistry of cyclooxygenase (COX)-2 inhibitors and molecular pathology of COX-2 in neoplasia

Several types of human tumors overexpress cyclooxygenase (COX) -2 but not COX-1, and gene knockout transfection experiments demonstrate a central role of COX-2 in experimental tumorigenesis. COX-2 produces prostaglandins that inhibit apoptosis and stimulate angiogenesis and invasiveness. Selective COX-2 inhibitors reduce prostaglandin synthesis, restore apoptosis, and inhibit cancer cell proliferation. In animal studies they limit carcinogen-induced tumorigenesis. In contrast, aspirin-like nonselective NSAIDs such as sulindac and indomethacin inhibit not only the enzymatic action of the highly inducible, proinflammatory COX-2 but the constitutively expressed, cytoprotective COX-1 as well. Consequently, nonselective NSAIDs can cause platelet dysfunction, gastrointestinal ulceration, and kidney damage. For that reason, selective inhibition of COX-2 to treat neoplastic proliferation is preferable to nonselective inhibition. Selective COX-2 inhibitors, such as meloxicam, celecoxib (SC-58635), and rofecoxib (MK-0966), are NSAIDs that have been modified chemically to preferentially inhibit COX-2 but not COX-1. For instance, meloxicam inhibits the growth of cultured colon cancer cells (HCA-7 and Moser-S) that express COX-2 but has no effect on HCT-116 tumor cells that do not express COX-2. NS-398 induces apoptosis in COX-2 expressing LNCaP prostate cancer cells and, surprisingly, in colon cancer S/KS cells that does not express COX-2. This effect may due to induction of apoptosis through uncoupling of oxidative phosphorylation and down-regulation of Bcl-2, as has been demonstrated for some nonselective NSAIDs, for instance, flurbiprofen. COX-2 mRNA and COX-2 protein is constitutively expressed in the kidney, brain, spinal cord, and ductus deferens, and in the uterus during implantation. In addition, COX-2 is constitutively and dominantly expressed in the pancreatic islet cells. These findings might somewhat limit the use of presently available selective COX-2 inhibitors in cancer prevention but will probably not deter their successful application for the treatment of human cancers.