Chemopreventive allylthiopyridazine derivatives induce apoptosis in SK-Hep-1 hepatocarcinoma cells through a caspase-3-dependent mechanism

Exopolysaccharides produced by Lactobacillus strains suppress HT-29 cell growth via induction of G0/G1 cell cycle arrest and apoptosis

In the present study, the effects of exopolysaccharides (EPS) from nine Lactobacillus strains with a high degree of bio-activity on human colon cancer cell line HT-29 were studied. The extracellular polymeric substances from 4 strains, namely K11, M5, SB27 and ×12, displayed desirable anti-proliferative activity against HT-29 cells. Crude and acidic EPS were purified from the 4 strains and the inhibitory effects were further investigated. The crude and acidic EPS from these 4 strains exerted anti-proliferation effects on HT-29 cells in a dose-dependent manner but were nontoxic to Vero cells. Treatment with EPS significantly induced G0/G1 cell cycle arrest and apoptosis of HT-29 cells. Hoechst 33258 staining of acidic EPS-treated HT-29 cells revealed different degrees of morphological changes within the nucleus and the formation of apoptotic bodies. Caspase-3 activity was markedly upregulated in HT-29 cells following treatment with acidic EPS. In addition, acidic EPS from the SB27 strain demonstrated the most robust inhibitory effect on HT-29 cells. The results of the present study suggest that as an inducer of apoptosis EPS has the potential to be applied in the treatment of colorectal cancer.

Immunopotentiation and antitumor effects of a ginsenoside Rg₃-fortified red ginseng preparation in mice bearing H460 lung cancer cells

Antitumor effects of a ginsenoside Rg(3)-fortified red ginseng preparation (Rg(3)-RGP) were investigated in human non-small cell lung carcinoma (H460) cells using in vitro cytotoxicity assay and in vivo nude mouse xenograft model. Immunomodulatory effects of the preparation were also assessed by measuring the facilitating activities on the nitric oxide (NO) release from peritoneal macrophages, in vitro and in vivo lymphocyte proliferation, and the carbon clearance from circulating blood. In a cell level, Rg(3)-RGP exerted H460 cytotoxicity and facilitated splenocyte proliferation at very high concentrations, without affecting NO production. However, oral administration of Rg(3)-RGP (100-300 mg/kg) enhanced carbon particle-phagocytic index of blood macrophages up to 360-397% of control value. In addition, Rg(3)-RGP significantly increased the splenocyte proliferation (23% at 100mg/kg). In tumor-bearing mice, 28-day oral treatment with Rg(3)-RGP (100mg/kg) remarkably suppressed the tumor growth, leading to the decrease of the tumor volume and weight by 30-31%, which was comparable to the effect (27-29% reduction) of doxorubicin (2mg/kg at 3-day intervals). While Rg(3)-RGP did not cause adverse effects, intravenous injection of doxorubicin markedly decreased body and testes weights, and exhibited severe depletion of spermatogenic cells in the atrophic seminiferous tubules. These results indicate that Rg(3)-RGP exerts antitumor activities via indirect immunomodulatory actions, without causing adverse effects as seen in doxorubicin.

Synthesis and anticancer activities of new 3-allylthio-6-(mono or disubstituted)aminopyridazines

A new series of 3-allylthio-6-(mono or disubstituted) aminopyridazines was synthesized by reacting 3-allylthio-6-chloropyridazine with several amines to develop new anticancer agents. These new compounds showed antiproliferative activities against lung cancer (A549), hepatoblastoma (Hep3b), prostate cancer (PC3), colon cancer (SW480) and cervical cancer (HeLa) cells in MTT assays, and could be promising candidates for chemotherapy of carcinomas. Compound 5 (3-allylthio-6-homopiperidinylaminopyridazine) showed higher potencies than 5-FU for inhibiting the growth of these cell lines. This suggests the potential anticancer activity of compound 5.

Synthesis of 3-alkylthio-6-allylthiopyridazine derivatives and their antihepatocarcinoma activity

The allylthio group of allicin and other organosulfur compounds, isolated from garlic, is considered a pharmacophore, and a key structure component of the molecule, which affords biological activities. In the foregoing studies, various 3-alkoxy-6-allylthiopyridazine derivatives (K-compounds) were synthesized, and their biological activities tested in animals. As expected, the various derivatives showed good hepatoprotective activities on carbon tetrachloride-treated mice and aflatoxin B1-treated rats, and chemopreventive activities on hepatocarcinoma cells in rats. Other new pyridazine derivatives, with the oxygen atom at the 3-position of the 3-alkoxy-6-allylthiopyridazine displaced by sulfur (S), were synthesized, and their activities tested in vitro. Thio-K6, one of the sulfur-substituted compounds, showed better chemopreventive activity toward hepatocarcinoma cells.

Phthalates inhibit tamoxifen-induced apoptosis in MCF-7 human breast cancer cells

Environmental estrogens represent a class of compounds that can mimic the function or activity of the endogenous estrogen 17 -estradiol (E2). Phthalates including butyl benzyl phthalate (BBP), di(n-butyl) phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP) are used as plasticizers, and also widely used in food wraps and cosmetic formulations. Phthalates have been shown to mimic estrogen and are capable of binding to the estrogen receptor (ER). It has been demonstrated that estrogen promotes drug resistance to tamoxifen (TAM) in breast cancer. In order to further evaluate the potential role of the phthalates as environmental estrogens, the effect of phthalates was investigated on TAM-induced apoptosis in MCF-7 human breast cancer cells. Our results show that phthalates, BBP (100 M), DBP (10 M), and DEHP (10 M), significantly increased cell proliferation in MCF-7, but not in MDA-MB-231 cells. In addition, BBP, DBP, and DEHP mimicked estrogen in the inhibition of TAM-induced apoptosis in MCF-7 cells. Our data suggest that the inhibitory effect of phthalates on TAM-induced apoptosis involves an increase in intracellular Bcl-2 to Bax ratio. Given that the phthalates are widely used in cosmetics mainly for women, our findings that revealed the promoting effect of BBP, DBP, and DEHP on chemotherapeutic drug resistance to TAM in breast cancer may be of biological relevance.

Antitumor activity of albendazole against the human colorectal cancer cell line HT-29: in vitro and in a xenograft model of peritoneal carcinomatosis

The peritoneal surface remains an important failure site for patients with colorectal cancer. We have recently shown that albendazole (ABZ), a safe and effective anthelmintic drug, has profound antitumor activity in hepatocellular cancer. Furthermore, albendazole also possesses unique physiochemical and pharmacokinetic properties probably making it a potential drug for use in the regional treatment of peritoneal carcinomatosis (PC). The current study was therefore designed to investigate this concept under both in vitro and in vivo conditions using human colorectal cancer cells HT-29. In cell culture, studies were conducted to investigate the effect of ABZ and its major metabolites, albendazole sulfoxide (ABZ-SO) and albendazole sulfone (ABZ-SO2) on the growth of human colorectal cell line HT-29. We also investigated the effects of ABZ on the cell cycle and the possible induction of apoptosis in these cells. Male nude mice inoculated intraperitoneally (i.p.) with HT-29 cells were treated with various schedules of ABZ given i.p. or orally for 6 weeks. Response was evaluated as the number of peritoneal tumor nodules present in animals at the end of the treatment period. In vitro, ABZ treatment of cells for 5 days led to profound inhibition of growth. (3)H-Thymidine assay and trypan blue viable cell counts confirmed the dose- and time-dependency of the ABZ effect, while recovery experiments revealed the reversible nature of this inhibition. ABZ-SO and ABZ-SO2 were also evaluated in cell culture studies and compared with the parent drug. In HT-29 cells, the IC(50) values were calculated to be 0.12 microM for ABZ and 2.35 microM for ABZ-SO. The other metabolite, ABZ-SO2, was completely inactive. Studies on the mechanism of ABZ action, revealed arrest of HT-29 cells at the G(2)/M phase of the cell cycle, while TUNEL, DNA laddering and caspase-3 activity all confirmed ABZ induced apoptosis. In nude mice with peritoneal HT-29 xenografts, ABZ profoundly inhibited peritoneal tumor growth. While alternate i.p. dosing (ABZ, 150 mg/kg) led to the highest degree of tumor growth suppression (P<0.001), schedules such as once-weekly dosing and even a single dose for the entire course of treatment (6 weeks) were also effective in reducing peritoneal tumor growth. However, no such activity was observed when ABZ was administered orally. This study shows for the first time the potent effect of regionally administered ABZ in suppressing the growth of peritoneal tumors of human colorectal origin. The effect is thought to be brought about by arresting tumor cells at the G(2)/M phase of the cycle and apoptosis. These findings provide evidence for potential value of ABZ in the treatment of regional PC arising from colorectal cell lines.

Synthesis of allylthiopyridazine derivatives and inhibition of aflatoxin B1-induced hepatotoxicity in rats

Five kinds of allylthiopyridazine derivatives were synthesized and their chemoprotective activities examined in rats exposed to aflatoxin B1-toxicant. Rats were pretreated with five allylthiopyridazine derivatives at daily oral doses of 50 mg/kg for 10 consecutive days, and during this period with one or three repeated doses of the potent hepatotoxin, aflatoxin B1. The hepatoprotective effects of the allylthiopyridazine derivatives against aflatoxin B1 (1 mg/kg, three times at intervals of 3 days, i.p., or at 3 mg/kg, once at final days, i.p.) administration were showed the significantly normal as compared with control in body and liver weights. Aspartate aminotransferase and alanine aminotransferase levels were markedly elevated after aflatoxin B1 administration, and pretreatment with allylthiopyridazine derivatives, before aflatoxin B1 administration, resulted in decreased levels of these enzymes. In addition, the allylthiopyridazine derivatives, K6 (3-methoxy-), K8 (3-chloro-), K16 (3-ethoxy-) and K17 (3-n-propoxy), induced elevated hepatic GSH levels. Four kinds of allylthiopyridazine derivatives investigated were effective against aflatoxin B1-induced hepatotoxicity.

Inhibition of invasion and induction of apoptosis by curcumin in H-ras-transformed MCF10A human breast epithelial cells

Curcumin, a dietary pigment in turmeric, posseses anti-carcinogenic and anti-metastatic properties. The present study was conducted to study in vitro chemopreventive effects of curcumin in transformed breast cells. Here, we show that curcumin inhibits H-ras-induced invasive phenotype in MCF10A human breast epithelial cells (H-ras MCF10A) and downregulates matrix metalloproteinase (MMP)-2 dose-dependently. Curcumin exerted cytotoxic effect on H-ras MCF10A cells in a concentration-dependent manner. Curcumin-induced cell death was mainly due to apoptosis in which a prominent downregulation of Bcl-2 and upregulation of Bax were involved. We also suggest a possible involvement of caspase-3 in curcumin-induced apoptosis. Curcumin treatment resulted in the production of reactive oxygen species (ROS) in H-ras MCF10A cells. Apoptotic event by curcumin was significantly inhibited by pretreatment of an antioxidant N-acetyl-L-cysteine (NAC), suggesting redox signaling as a mechanism responsible for curcumin-induced apoptosis in H-ras MCF10A cells. Taken together, our results demonstrate that curcumin inhibits invasion and induces apoptosis, proving the chemopreventive potential of curcumin.