Induction of apoptosis in an estrogen-responsive mouse Leydig tumor cell by leukotriene

For estrogen-responsive B-1F cells, established from estrogen-responsive mouse Leydig cell tumor, it has been reported that the 5-lipoxygenase (5-LOX) metabolic pathway appears to be associated with cell growth. The addition of 5-LOX inhibitor 2-(12-hydroxydodeca-5,10-diyl)-3,5,6-trimethyl-1,4-benzoquinone (AA861) to the medium resulted in a dose-dependent increase in cell yield as described previously. When the growth of the palpable tumors was measured, AA861 had stimulated in vivo tumor growth in adult male mouse inoculated B-1F cells. The effects of AA861 and 17beta-estradiol (E2) on the contents of various arachidonic acid metabolites in B-1F cells and their conditioned medium were examined. Although AA861 and E2 decreased the contents of leukotrienes (LTs), the two did not significantly change those of prostaglandins, thromboxan, prostacyclin, 12-hydroxyeicosatetraenoic acid (HETE) and 15-HETE. In immunohistochemical study B-1F cells show positive staining for 5-LOX in the E2-depleted condition, while E2 decreased the expression of 5-LOX. The decrease of the intensities of 79-kDa 5-LOX protein and 403-bp RT-PCR product bands was observed. The growth of Morpholino-anti oligo delivered B-1F cells was higher than that of Standard control oligo delivered cells. The delivery of Morpholino-anti oligo into B-1F cells caused the decrease of contents of LTs and 5-HETE in the cells and medium, and the reduction of 5-LOX activity. When LTD4 was added in the culture medium, the increasing concentrations of LTD4 resulted in a significant inhibition of cell yields of E2-treated B-1F cells. Morphological changes such as nuclear condensation and fragmentation, and DNA ladder pattern were demonstrated in E2-stimulated B-1F cells treated with LTD4 as well as in control cells cultured in the basal medium. These results implicate that 5-LOX at least plays an important role in the growth of B-1F cells and LD4 induces the apoptosis of B-1F cells.

Phase I trial of concurrent chemoradiotherapy with docetaxel, cisplatin and 5-fluorouracil (TPF) in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN)

The aim of this study was to evaluate the efficacy and toxicity of a concurrent chemoradiotherapy using docetaxel, cisplatin and 5-fluorouracil (5-FU) (TPF) in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). In total, 19 patients with previously untreated stage III–IV SCCHN were entered onto this trial. Patients received two cycles of chemotherapy. Cycles were repeated every 4 weeks. The starting doses (dose level 1) were docetaxel 60 mg m⁻², cisplatin 70 mg m⁻², and 5-day continuous infusion of 5-FU 600 mg m⁻² day⁻¹. Radiation was targeted to begin on the first day of chemotherapy, day 1. The total radiation dose to the primary tumour site and neck lymph nodes was between 63.0 and 74.0 Gy. At least three patients were examined at each dose level before advancing to the next level. The maximum-tolerated dose (MTD) of this regimen was docetaxel 60 mg m⁻², cisplatin 60 mg m⁻² and 5-FU 600 mg m⁻² day⁻¹. The main toxicities were mucositis (grade 3 and 4, 79%), leukocytopenia (grade 3 and 4, 53%), neutropenia (grade 3 and 4, 42%), anaemia (grade 3, 16%), liver dysfunction (grade 3, 11%) and renal dysfunction (grade 2, 11%). The overall response rate was 100%, including 84% complete responses (CRs). This concurrent chemoradiotherapy with TPF was safe and well tolerated. The high CR rate justifies further evaluation of this chemoradiotherapy modality in advanced SCCHN patients.

Induction of apoptosis in an androgen-dependent mouse mammary carcinoma cell line by methylcobalamin

SC-3 is a cloned cell line derived from an androgen-dependent mouse mammary tumor (Shionogi Carcinoma 115). A physiological level of androgen stimulates the growth of SC-3 cells through the production of androgen-induced growth factor. Methylcobalamin (MeCbl), one of the active cobalamins, inhibits the growth of SC-3 cells stimulated by androgen. It is known that apoptosis has an important role in tumor growth. The specific aim of this study is to examine the effects of MeCbl, in the presence of androgen, on apoptosis in SC-3 cells. Morphological analysis revealed budding nuclei and chromatin condensation in cells cultured with MeCbl, but few in cells cultured without MeCbl. Low molecular weight DNA extracted from cells cultured with or without MeCbl was analysed by gel electrophoresis. A characteristic nucleosomal size ladder was detected in the culture with MeCbl. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end-labelling method was also used to evaluate apoptotic cell death in SC-3 cells. Apoptosis was observed more frequently in SC-3 cells treated with MeCbl than in those without MeCbl. These results demonstrate that androgen-dependent SC-3 cells undergo apoptosis by MeCbl even if in the presence of androgen.

Methylcobalamin decreases mRNA levels of androgen-induced growth factor in androgen-dependent Shionogi carcinoma 115 cells

Methylcobalamin (MeCbl) is an important enzyme cofactor required for methionine synthase activity. It also inhibits, in a dose-dependent manner, the proliferation of an androgen-dependent cell line, SC-3, derived from an androgen-dependent mouse mammary tumor (Shionogi carcinoma 115). In SC-3 cells, androgen induces the production of androgen-induced growth factor (AIGF), an autocrine growth factor increasing the proliferation of SC-3 cells. MeCbl treatment suppressed the androgen-induced, AIGF-mediated growth of SC-3 cells, as well as the androgen-induced increase of AIGF mRNA. In SC-3 cells, androgen receptors linked with androgen form complexes that tightly bind DNA and act as transcription factors in the nucleus to regulate the expression of specific genes such as AIGF. The number and dissociation constants of androgen receptors in control and MeCbl-treated SC-3 cells were the same. Similarly, the extent of binding of normal androgen receptors in nuclei from control and MeCbl-treated cells was virtually identical. The androgen receptors from control and MeCbl-treated cells showed similar capacities for conversion to a form that tightly binds to DNA on heat activation. These results suggest that the reduction of AIGF mRNA, subsequent to the nuclear binding of androgen receptors, may be a partial cause of the growth-inhibitory activity of MeCbl in SC-3 cells.

Cytotoxic activity of normal mouse serum on mouse tumor cells in vitro

Cytotoxic effects of normal mouse serum on mouse tumor cells were investigated in vitro. When FE melanoma cells of C57BL/6 mouse origin, were cultured in medium containing 1% fetal calf serum (FCS) and 10-30% C57BL/6 mouse serum, number of viable FE cells markedly decreased after a little increase in their number, indicating cell death of FE cells in culture with mouse serum. Phase-contrast microscopic examination showed appearance of fatty degeneration in FE cells after 24 h, and an increase in cell death after 48 h. Electron microscopic examination, and agarose gel electrophoresis of DNA at 72 h of culture showed that their cell death occurred as necrosis. This cytotoxic effect of mouse serum was also found in culture of combinations of C57BL/6 mouse serum and C57BL/6 mouse melanoma cells (G6 cells), and BALB/c mouse serum and various BALB/c mouse tumor cells (G-5 and G-1 liver tumor cells, and Colon 26 cells). Furthermore, sera of BALB/c and B10D2 mice also showed the cytotoxic effect on FE cells. The cytotoxic effect of mouse serum was not ascribed to complement activity because all mouse sera were treated at 56 degrees C for 30 min before use, and this heat treatment completely abolished complement activity, and because serum of C5-deficient mice also showed the cytotoxic effect. This cytotoxic activity was stable at heat treatment at 100 degrees C for 10 min, and was in a serum fraction of molecular weights more than 30,000 dalton. The present results show that normal mouse serum has a factor(s) inducing fatty degeneration and necrosis of mouse tumor cells.

Increased experimental pulmonary metastasis in pregnant mice

The effect of pregnancy on experimental pulmonary metastasis was studied. Compared to the incidence of pulmonary metastasis induced by G6 cells in non-pregnant mice, the incidence of such metastasis was found to be greatly enhanced when the cells were injected i.v. in the latter half of pregnancy. The maximum enhancement was seen on the 15th day of pregnancy. The incidence of pulmonary metastasis returned to the level observed in non-pregnant mice when the cells were injected 4 days after parturition. Pregnancy also significantly increased the incidence of pulmonary metastasis of 2 other cell lines (3LL and Colon 26). Injection of G6 cells after hysterectomy performed on the 15th day of pregnancy resulted in decreased lung colonization, similar to that seen after parturition. Quantificative analysis of the arrest of G6 cells labeled with [125I]-5-iodo-2'-deoxyuridine in the lungs showed that the tumor-cell clearance from the lungs during the 24-72 hr after tumor-cell injection was much slower in pregnant than in non-pregnant mice. The continuous administration of beta-estradiol and/or progesterone, which maintained serum levels of the hormones equivalent to those prevailing on the 15th day of pregnancy, did not affect the lung colonization of G6 cells. Tumor-cell-platelet aggregation was more extensive with platelets obtained from mice at the 15th day of pregnancy than with those from non-pregnant mice. When platelets isolated from pregnant mice were injected into normal mice 5 min before G6 injection, lung metastasis was also enhanced. These findings suggest that a pregnant host is handicapped with regard to pulmonary metastasis, this being partly due to increased platelet-aggregating activity in response to tumor cells.

Differential effect of sodium butyrate on cyclic AMP phosphodiesterase activities in butyrate sensitive and resistant mastocytoma cells

The effect of sodium butyrate on the intracellular cyclic AMP levels and the activities of cyclic AMP-regulating enzymes were examined in two types of mastocytoma p-815 cells in culture: one type (S cell) was sensitive and the other (R cell) was resistant to the induction of differentiation by sodium butyrate. In the presence of sodium butyrate, adenylate cyclase activity increased in both S and R cells to the same degree, whereas the level of cyclic AMP was elevated only in S cells. Cyclic AMP phosphodiesterase activity increased in R cells but not in S cells. Cyclic AMP phosphodiesterase activities of two cell populations differed in their response to sodium butyrate and they seem to have an important role in regulating cellular level of cyclic AMP that might be an important factor in controlling cell differentiation.

Extrusion of nuclei of murine suspension culture cells with microtubule poisons

Microtubule poisons such as colchicine, colcemid and vinblastine caused extrusion of nuclei of murine suspension culture cells (mastocytoma p-815 cells, myeloma PU-3 cells, leukemia M1 cells). Enucleation did not follow spontaneously in most cells, but it did occur when the treated cells were centrifuged in Separate-L gradient. These poisons did not induce nuclear extrusion in cells growing in monolayer (L cells, BALB/c 3T3 cells, SV40-transformed BALB/c 3T3 cells, histiocytoma HC-11 cells). Cytochalasin B (CB) that had been reported to cause nuclear extrusion in the cells cultured in monolayer [1] did not induce the extrusion in the suspension culture cells but inhibited the colchicine-induced nuclear extrusion.

Correlation of alkaline phosphatase activity with cell population density in tissue culture cells originated from rat liver

Alkaline phosphatase (ALP) activity of cultured Li-10 cells obtained from rat liver was found to be a function of cell population density. After the cells grew to confluence, the enzyme activity per cell increased about 100 times that at a low population density. The increase of activity was inhibited by the addition of actinomycin D or cycloheximide to the culture medium. When the cells that had gained high ALP activity after confluency were subcultured, ALP activity decreased to a low basal level after about 48 h. Under cytochemical examination using an electron microscope, the induced ALP activity was seen exclusively at the apical surface region of the cells but scarcely at cell-cell and cell-substratum contact regions.

Changes in the cellular glycosaminoglycans of cultured mastocytoma cells induced by sodium butyrate

The effect of sodium butyrate on the cellular glycosaminoglycans of cultured mastocytoma p-815-4 cells was investigated using enzymic digestion, electrophoresis, nitrous acid degradation, and sequential partition fractionation. The average cellular glycosaminoglycan content of mastocytoma p-815-4 cells grown in the presence of 2 mM sodium butyrate was ten times as much as that of the control p-815-4 cells. Approximately 90% of the glycosaminoglycans isolated from the control cells and 70% from the butyrate-treated cells were found to be chondroitin 4-sulfate by enzymic digestion. The remainders were chondroitinase ABC-resistant. Hyaluronic acid and dermatan sulfate were not detected in either control cells or butyrate-treated cells. The chondroitinase ABC-resistant fraction of glycosaminoglycans from butyrate-treated cells showed a molar ratio of sulfate to uronic acid of more than 2.0, and provided some physicochemical properties characteristic to reference bovine lung heparin.