Parathyroid hormone stimulates phosphoinositide metabolism and intracellular calcium mobilization in osteoblast-like clone MC3T3-E1 cells

The effects of parathyroid hormone (rat 1–34 fragment, rPTH) on phosphoinositide metabolism and intracellular Ca²⁺ mobilization were studied in a osteoblast-like clone MC3T3-E1 cells. rPTH caused a transient rise in intracellular Ca²⁺ in a dose-dependent manner. Significant Ca²⁺ increase was still observed under the extracellular Ca²⁺-free condition. In addition, 100nM rPTH stimulated rapid formation of both 1,2-diacylglycerol (1,2-DAG) and inositol 1,4,5-trisphosphate (Ins(1,4,5)P₃), indicating agonist-triggered hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP₂). The current observations suggested that the rPTH-induced increase of intracellular Ca²⁺ was in part due to internal Ca²⁺ release mediated by Ins(1,4,5)P₃. These results indicate possible involvement of phosphoiniositide metabolism in signal transduction of PTH-stimulated osteoblastic cells.     

Human group IIA secretory phospholipase A2 induces neuronal cell death via apoptosis.

Expression of group IIA secretory phospholipase A2 (sPLA2-IIA) is documented in the cerebral cortex (CTX) after ischemia, suggesting that sPLA2-IIA is associated with neurodegeneration. However, how sPLA2-IIA is involved in the neurodegeneration remains obscure. To clarify the pathologic role of sPLA2-IIA, we examined its neurotoxicity in rats that had the middle cerebral artery occluded and in primary cultures of cortical neurons. After occlusion, sPLA2 activity was increased in the CTX. An sPLA2 inhibitor, indoxam, significantly ameliorated not only the elevated activity of the sPLA2 but also the neurodegeneration in the CTX. The neuroprotective effect of indoxam was observed even when it was administered after occlusion. In primary cultures, sPLA2-IIA caused marked neuronal cell death. Morphologic and ultrastructural characteristics of neuronal cell death by sPLA2-IIA were apoptotic, as evidenced by condensed chromatin and fragmented DNA. Before apoptosis, sPLA2-IIA liberated arachidonic acid (AA) and generated prostaglandin D2 (PGD2), an AA metabolite, from neurons. Indoxam significantly suppressed not only AA release, but also PGD2 generation. Indoxam prevented neurons from sPLA2-IIA-induced neuronal cell death. The neuroprotective effect of indoxam was observed even when it was administered after sPLA2-IIA treatment. Furthermore, a cyclooxygenase-2 inhibitor significantly prevented neurons from sPLA2-IIA-induced PGD2 generation and neuronal cell death. In conclusion, sPLA2-IIA induces neuronal cell death via apoptosis, which might be associated with AA metabolites, especially PGD2. Furthermore, sPLA2 contributes to neurodegeneration in the ischemic brain, highlighting the therapeutic potential of sPLA2-IIA inhibitors for stroke.     

Predicting chemotherapeutic response to small-cell lung cancer of platinum compounds by thallium-201 single-photon emission computerized tomography.

Thallium-201 single-photon emission computerized tomography (SPECT) was used to clarify the relationship between 201Tl uptake and the response in chemotherapy to platinum compounds in 21 patients with small-cell lung cancer. 201Tl-SPECT scans were obtained twice: at 15 min (early scan) and 120 min (delayed scan) after an intravenous injection of 111 MBq (3 mCi) of thallium-201 chloride. We obtained the uptake ratio from each scan and calculated the retention index:uptake ratio = region of interest uptake/contralateral normal lung uptake; retention index = (delayed ratio - early ratio)/early ratio. After 201Tl scintigraphy, 12 patients received chemotherapy consisting of platinum compounds and nine were treated with chemoradiation. Among patients receiving only chemotherapy, the retention index correlated with the responses to chemotherapy. In an in vitro study, ouabain, an inhibitor of the Na,K-ATPase pump, reduced sensitivity to cisplatin and inhibited intracellular thallium uptake in the small-cell lung cancer cell line. These studies suggest that 201Tl-SPECT is a useful indicator of response to chemotherapy with platinum compounds in small-cell lung cancer, and that Na,K-ATPase is commonly involved in transporting both thallium and platinum compounds into cancer cells.     

Treatment of cancer of the gallbladder and bile ducts

Cancer of the gallbladder carries a grim prognosis, because the disease is usually too advanced and surgically incurable at the laparotomy. In our series, the curative resection rate is only 16.7%. However, palliative resection with postoperative irradiation have possible effects on the prolongation of survival periods. Cancer of the bile duct has better prognosis, than that of the gallbladder, because the early occurrence of obstructive jaundice often leads to curative resection. In our series, however, the curative resection rate is only 50.0%. More aggressive surgical therapy might improve the surgical figures. In addition, postoperative radiation therapy and immuno-chemotherapy may have possible effects as adjuvant therapy.     

Implantation of genetically manipulated fibroblasts into mice as antitumor alpha-interferon therapy

Long-term parenteral administration of human alpha-interferon (HuIFN-alpha) is effective in the treatment of several malignancies, including chronic myelocytic leukemia. In the present study, a model for fibroblast-mediated HuIFN-alpha gene therapy for the treatment of chronic myelocytic leukemia is described. Human IFN-alpha 5 complementary DNA was inserted into a bovine papilloma virus plasmid vector (BMGNeo) containing a neomycin resistance gene. The recombinant plasmid (BMGNeo-IFN) was transfected into NIH/3T3 fibroblasts by the calcium phosphate coprecipitation method, and stably transformed cells were isolated by G418 selection. A fibroblast clone secreting a large amount of HuIFN into the culture supernatant was selected by radioimmunoassay using anti-HuIFN-alpha monoclonal antibodies. Southern blot analysis revealed that the transformed cells contained approximately ten copies of the BMGNeo-IFN plasmid per cell, and Northern blot analysis demonstrated high expression of HuIFN-alpha mRNA in the cells. This fibroblast clone strongly suppressed proliferation of a HuIFN-alpha-sensitive chronic myelocytic leukemia cell line (KU812) during cocultivation in vitro. When the HuIFN-alpha-producing fibroblasts were implanted into nude mice bearing KU812 tumors by the subcutaneous diffusion chamber method, tumor growth in vivo was also significantly suppressed. This study suggests the clinical potential of fibroblast-mediated gene therapy in the future.     

Solitary Metastatic Malignant Melanoma of the Small Intestine: Findings Obtained during Intraoperative Enteroscopy

Abstract: A 59-year-old male with an established diagnosis of malignant melanoma of the nasal cavity plus multiple pulmonary metastases was referred to our hospital because of abdominal pain and vomiting. Double-contrast study of the small intestine revealed a filling defect in the middle of the ileum. lntraoperative enteroscopy revealed that the ileal tumor was ulcerated, and that it was covered by ileal mucosa of normal appearance. Because no other lesions were identified within the intestine, the ileal segment with the tumor was surgically removed. The tumor was diagnosed as malignant melanoma with a histology similar to that of nasal mass. The patient has survived for the subsequent 13 months, during which no gastrointestinal symptoms recurred. Our case suggests that metastasis should be included in the differential diagnosis of a single small intestinal tumor. (Dig Endose 1999; 11: 47–51)     

Human alveolar macrophages: wheat germ agglutinin-dependent tumor cell killing

Human alveolar macrophages (AM) obtained by bronchoalveolar lavage from healthy donors were examined for ability to cause lectin-dependent tumor cell killing. Of five plant and two animal lectins tested, only one lectin, wheat germ agglutinin (WGA), induced significant and reproducible lectin-dependent macrophage-mediated cytotoxicity (LDMC) against human bladder cancer (T-24) cells. There was no significant difference between the LDMCs of AM and blood monocytes. All 6 tumor cell lines tested were sensitive to various extents to LDMC induced by WGA. Quantitative analysis with WGA-FITC conjugate showed the presence of various levels of receptors for WGA on the surface of AM, monocytes and tumors. A relatively good correlation was found between the sensitivities of the tumor cells to LDMC mediated by AM and the numbers of receptors for WGA. Pretreatment of AM or monocytes with LPS did not affect their LDMC. These results indicate that a plant lectin, WGA which binds to both human AM and tumor cells, renders human AM cytotoxic to allogeneic tumor cells by a different mechanism(s) from that involved in the nonspecific tumor cytotoxicity of activated macrophages.     

Establishment of an Epstein-Barr virus (EBV) genome-positive subline of Ramos (Ramos/NPC) following infection of Ramos with nasopharyngeal carcinoma (NPC)-derived EBV

An Epstein-Barr virus (EBV) genome-positive epithelial hybrid cell line, NPC-KT, derived from the fusion of primary nasopharyngeal carcinoma cells with a human epithelial cell line of adenoid origin has previously been described (Takimoto, Kamide, and Umeda, 1984a; Takimoto, Ogura, Sato, and Hatano, 1984b; Takimoto, Ogura, Sato, Umeda, and Hatano, 1985). The NPC-KT cells produce virus (NPC virus) with both transforming and lytic properties. An EBV genome-negative human lymphoblastoid cell line, Ramos, was infected with NPC virus. Three months after infection, more than 90% of the cell population expressed EBV-associated nuclear antigen (EBNA). Approximately 40% of the cells exhibited a brilliant pattern, whereas the remaining 50% of the cells showed a faint granular pattern. The result suggests that there may be heterogeneity in NPC virus.