Expression pattern of Galectin 4 in rat placentation.

Galectin 4 (Gal4) is abundantly expressed in the epithelium of the gastrointestinal tract, and functional analysis has concentrated on its roles associated with polarized membrane trafficking. This study aimed to investigate the expression of Gal4 in placentation. The expression level of Gal4 was revealed to be lower in differentiated Rcho-1 cells (a model system of rat trophoblast differentiation) than in proliferative cells. In the rat placenta, immunohistochemical analysis showed that Gal4 is preferentially located in the maternal-fetal junctional zone. These results suggest that down-regulation of Gal4 may be involved in the promotion of trophoblast cell differentiation.

Apoptosis and epithelial phagocytosis in mitomycin C-treated human pulmonary adenocarcinoma A549 cells.

Fate of human cancer cells damaged by mitomycin C was investigated by electron microscopy. In a monolayer culture of pulmonary adenocarcinoma A549 cells, the antitumor drug mitomycin C induced dilation of the smooth endoplasmic reticulum and Golgi apparatus. Simultaneously, the myelin figures, autophagosomes and dense tonofilament bundles were formed in the cytosol. Nuclear changes also included nucleolar condensation, as well as the disappearance of the karyosomes and thinned marginal heterochromatins. These nuclei came to be rigid and densely chromatic, finally resulting in apoptosis. There was no alteration in the mitochondria or rough endoplasmic reticulum. Meanwhile, some remaining intact A549 cells extended their cytoplasm toward detached cells and engulfed them. These results indicate that mitomycin C induces apoptosis in A549 cells and concurrently stimulates epithelial phagocytotic activity against their own damaged cells.

Induced apoptosis and necrosis by 2-methylfuranonaphthoquinone in human cervical cancer HeLa cells.

2-Methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) has been reported to be more cytotoxic to human malignant tumor cell lines than are the corresponding normal epithelial cells. Therefore, we examined the dose response of FNQ3 against human cervical cancer HeLa cells in culture. When 1.25 mg/ml FNQ3 was applied, apoptosis was induced, as determined by an immunohistochemical staining of fragmented genome DNA and cell profiles. Significant inhibition of Bcl-2 oncogene protein expression by the same concentration of FNQ3 also was demonstrated by an immunohistochemical staining method to visualize the expressed cells and Western blot in polyacrylamide gel electrophoresis. Flow-cytometric spectra showed S-phase arrest in cell cycles and the appearance of sub-G1 phase consistent with apoptosis. On the other hand, concentrations of 5 microg/ml or more of FNQ3 induced necrosis. These results show that FNQ3 may act as an antitumor agent to induce apoptosis by affecting Bcl-2 expression and cell cycles, or necrosis as the result of primary mitochondrial injuries.

Furanonaphthoquinone analogs possessing preferential antitumor activity compared to normal cells.

The 50% growth inhibition toxicity (IC50 at 72 h) of 16 synthetic and 2 phytochemical natural analogs of furanonaphthoquinones (naphtho[2,3-b]furan-4,9-dione; FNQ) and 2 analogs of isofuranonaphthoquinones was assayed in vitro in respect to established human cervical cancer and lung adenocarcinoma cells in comparison with human uterine endocervical, tracheal and bronchiolar epithelial cells and fibroblasts. Prostate, cholangio, colon, laryngeal, and tongue carcinoma cell lines and two osteosarcoma cell lines were also used for the assay. The IC50 ratio of normal cells to cancer cells was estimated in order to represent preferential antitumor activity. Two analogs, 2-methylnaphtho[2,3-b]furan-4, 9-dione (FNQ3) and 2-methyl-5(or 8)-hydroxynaphtho[2,3-b]furan-4, 9-dione (FNQ13) showed 10.4 to 14.1 IC50 ratios for all carcinoma cells used, indicating a wide spectrum. Among different carcinomas, there was no difference or variety in the IC50 ratio of a single analog. A moderate IC50 ratio (3.1-4.7) was also found in nine analogs, but seven others were equally cytotoxic (less than 2.6) to both cancer and normal cells. Two isofuranonaphthoquinone derivatives were ineffective, but a thieno derivative was equally cytotoxic to all cells tested. On the basis of the IC50 ratio data and the structure of the furanonaphthoquinones, the following structural activity (selectivity) relationship can be postulated: (i) the presence of an alkyl group at position 2 enhances the IC50 ratio, particularly the methyl group; (ii) a hydroxyl group at position 5 or 8 enhances the IC50 ratio; and (iii) methylation of the phenolic hydroxyl group leads to a decrease of potency. These results indicate that FNQ3, 13, and some other analogs are more preferentially cytotoxic to human tumor cells than to normal cells, unlike mitomycin-C, adriamycin, carboplatin, and methotrexate which are cytotoxic to the both. In nude mouse xenograft tests, FNQ3 demonstrated a significant antitumor activity with T/C% values of 16. 6 to 41.6 against several human carcinoma and osteosarcoma cells.

Mitochondrial NADH-quinone oxidoreductase of the outer membrane is responsible for paraquat cytotoxicity in rat livers.

We investigated the existence of an NADH-dependent paraquat (PQ) reduction system in rat liver mitochondria (Mt) in respect to the cytotoxic mechanisms of PQ. The outer membrane fractions, free from the contamination of inner membranes but with a few microsomes, catalyzed rotenone-insensitive NADH, but not NADPH, oxidation by menadione or PQ. Anti-NADH-cytochrome b5 reductase antibody and its inhibitor p-hydroxymercuribenzonate did not inhibit the NADH-PQ reduction activity. Therefore, the respiratory systems of the inner membranes and microsomal cytochrome P450 systems could not have been responsible for the reaction. Dicoumarol, an inhibitor of NAD(P)H-quinone oxidoreductase (NQO), dose dependently suppressed the NADH oxidation in the outer membrane via PQ as well as menadione, with I50 values of 190 (for menadione) and 150 microM (for PQ). Because of a lower sensitivity to NADPH and the higher doses of dicoumarol required for its inhibition, the activity in the outer membrane may be an "NADH-quinone oxidoreductase" which partly differs from the NQO previously reported. This outer membrane enzyme produced superoxide anions in the presence of both NADH and PQ and was too tightly membrane-bound to be extracted by Triton X-100 and deoxycholate. From these results, we concluded that the free radical-producing mitochondrial NADH-quinone oxidoreductase is a novel oxidation-reduction system participating in PQ toxicity. This is in good agreement with our previous results showing that PQ selectively damaged Mt in vivo and in vitro, resulting in cell death (K.-I. Hirai et al., 1992, Toxicology 72, 1-16).

Inhibitory effect of furanonaphthoquinone derivatives on the replication of Japanese encephalitis virus.

Japanese encephalitis still occurs in endemic and epidemic forms over a wide area of Asia. Although the vaccine against Japanese encephalitis virus (JEV) is widely used, no antiviral drug has been reported. We used several different kinds of furanonaphthoquinone derivatives and found antiviral activity against JEV. Especially, 2-methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) indicated the highest antiviral activity, followed by 2-(1-hydroxyethyl)-, 5(or 8)-hydroxy-, and 2-methyl-5(or 8)-hydroxy-analogs of naphtho[2,3-b]furan-4,9-dione. In the presence of 3 microg/ml FNQ3, the virus yields in Vero cells were 2 x 10(5) PFU/ml at 24 h after infecting with the virus and 10% of the control level. Western blot analysis using anti-E rabbit sera or anti-NS3 showed that the expression of viral proteins was inhibited by treatment with FNQ3. In addition, Northern blot analysis indicated that the appearance of JEV-RNA was also inhibited by FNQ3. These results suggest that FNQ3 inhibits JEV replication through viral RNA and protein synthesis.

Mitochondrial damage by a new antitumour agent furanonaphthoquinone derivative in human cervical cancer HeLa cells.

The intracellular ultrastructural changes induced by the new antitumour agent 2-methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) were investigated in human cervical cancer HeLa cells in comparison with normal cervix cells. The normal cells were isolated from cervixes surgically resected from myoma patients and were keratin positive. FNQ3 at 3-5 micrograms ml-1 selectively damaged the HeLa cell mitochondria followed by rough-surfaced endoplasmic reticulum resulting in cell death. In contrast, normal cells remained unaffected at that concentration but were damaged by 20 micrograms ml-1 FNQ3. The FNQ3-induced tumour cell toxicity was inhibited 52% and 36% by trolox and a water-soluble fraction of the antioxidative substance AOB, respectively. The results indicated that FNQ3 is selectively toxic to HeLa cells at approximately eight times that of normal cells in terms of mitochondrial alteration and free radical formation.