Se-methylselenocysteine inhibits phosphatidylinositol 3-kinase activity of mouse mammary epithelial tumor cells in vitro

50 Background: In vitro chemosensitivity testing of circulating epithelial tumor cells (CETCs) provides real-time information about the sensitivity of the tumor cells present in the patient. Nevertheless, a fraction of CETCs can survive after conventional chemotherapy and grow into distant metastasis. This may be a subpopulation of CETCs with proliferation activity which has the ability to form floating spheres in suspension culture. Spheroids exhibit stem cell-like properties and may be responsible for chemotherapeutic resistance. Therefore, the aim of our study was to determine the efficacy of chemotherapeutics on spheroids cultured from CETCs. Methods: The enumeration of CETCs from patients with solid tumors in clinical stage I to IV was performed using the maintrac method. Subsequently, CETCs in the context of the surrounding white blood cells were cultured in a suspension culture allowing for spheroid formation. To evaluate the cytotoxic effect of drugs on CETCs and spheroids we exposed them to anticancer drugs in short time culture in different concentrations and for different periods of time. Results: In contrast to CETCs, spheroids were significantly more chemotherapy resistant. Active drugs led to disintegration of tumor spheres. Interestingly, some cells in the spheres were able to survive. Epirubicin and especially salinomycin, a polyether ionophore antibiotic isolated from Streptomyces albus, showed high efficacy in a high proportion of cells. Furthermore, our data suggested that curcumin, a natural biologically active compound that is extracted from the plant Curcuma longais a promising agent for cancer treatment. Docetaxel, cyclophosphamide, and 5-fluoruracil showed lower cytotoxic effects onto the cells in the spheres. Conclusions: Our results show, for the first time, that stem cells circulating in peripheral blood, capable of forming spheroids are way more resistant to anticancer drugs than the remnant circulating tumor cells. We, furthermore, demonstrate that salinomycin and curcumin efficiently destroy spheroids cultured from CETCs, strengthening their role as promising anticancer therapeutics.

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In vitro and in vivo suppression of growth of rat liver epithelial tumor cells by antisense oligonucleotide against protein kinase C-α

Journal of Hepatology ◽

10.1016/s0168-8278(00)80011-2 ◽

2000 ◽

Vol 33 (4) ◽

pp. 601-608 ◽

Cited By ~ 15

Author(s):

Shwu-Bin Lin ◽

Li-Ching Wu ◽

Siao-Ling Huang ◽

Hui-Lun Hsu ◽

Sung-Hwa Hsieh ◽

...

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Tumor Cells ◽

Rat Liver ◽

Antisense Oligonucleotide ◽

Epithelial Tumor ◽

Kinase C ◽

Epithelial Tumor Cells

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Regulation of phosphatidylinositol 3-kinase by insulin in rat skeletal muscle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1993.265.5.e736 ◽

1993 ◽

Vol 265 (5) ◽

pp. E736-E742 ◽

Cited By ~ 8

Author(s):

K. S. Chen ◽

J. C. Friel ◽

N. B. Ruderman

Keyword(s):

Skeletal Muscle ◽

Soleus Muscle ◽

Protein Tyrosine Kinase ◽

Kinase Activity ◽

Receptor Protein ◽

Mammalian Skeletal Muscle ◽

Phosphatidylinositol 3 Kinase ◽

Phosphatidylinositol 3

The presence of phosphatidylinositol 3-kinase (PI 3-kinase) in mammalian skeletal muscle and its response to insulin stimulation were investigated. PI kinase, immunoprecipitated from rat soleus muscle with antibodies directed toward its 85-kDa subunit phosphorylated PI, phosphatidylinositol 4-phosphate [PI(4)P], and phosphatidylinositol 4,5,-bisphosphate [PI(4,5)P2] to yield phosphatidylinositol 3-phosphate [PI(3)P], phosphatidylinositol 3,4,-bisphosphate, and phosphatidylinositol trisphosphate in vitro. PI 3-kinase activity was also immunoprecipitated with antiphosphotyrosine [alpha-Tyr(P)] antibodies and with antibodies raised against IRS-1, a substrate of the insulin receptor protein tyrosine kinase that associates with and activates PI 3-kinase. Incubation of the soleus with insulin in vitro, or injection of insulin into rats in vivo, produced three- to fivefold increases in alpha-Tyr(P)- and alpha-IRS-1-immunoprecipitable PI 3-kinase activity. In nonstimulated soleus muscle, PI 3-kinase activity immunoprecipitated with alpha-IRS-1 or with alpha-Tyr(P) antibodies was evenly distributed between particulate (200,000-g pellet) and soluble fractions. Insulin treatment increased immunoprecipitable PI 5-kinase activity in both fractions, but the increase in alpha-Tyr-(P)-precipitable activity was greater in the particulate fraction, whereas the increase in alpha-IRS-1-precipitable activity was greater in the soluble fraction. In intact soleus muscles incubated with 32PO4, insulin increased the labeling of PI(3)P but did not affect the labeling of PI(4)P or PI(4,5)P2. Activation of PI 3-kinase by insulin was unaffected by prior denervation of the muscle, a manipulation that has been shown to cause both insulin resistance and hypersensitivity in muscles, depending on the parameter measured.(ABSTRACT TRUNCATED AT 250 WORDS)

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