Tumor cell preparation

For purposes of quality control, any cell preparation used in the screen (see below) needs to have a definitive or consensus diagnosis and grading determined by histological examination. Furthermore, tumor cell preparations must be at least 80% tumor cells (as determined by cytopathological examination), whereas normal cell preparations must be devoid of any tumor cells. Cell viability, determined by trypan-blue exclusion, must be a minimum of 70%, and the signal-to-noise ratios for a predetermined cell cluster concentration must be at least threefold. 

A-Acetyl-9-deoxy-9-fluoroneuraminic acid (591) was prepared by treatment of a protected 6-hydroxyl precursor with A, A-diethylaminosulfur trifluoride (DAST) or through condensation of 2-acetamido-2,6-dideoxy-6-fluoro-D-mannopyranose with potassium di(/ >r/-butyl) oxaloacetate. Compound 591 is a substrate for cytidine monophosphate (CMP)-sialic acid synthetase, giving rise to CMP-5-A-acetyl-9-deoxy-9-fluoroneuraminic acid, which is cytotoxic against tumor cells. 5-A-Acetyl-3-fluoroneuraminic acids 592-594 were prepared through fluorine (or acetyl hypofluorite) addition (in AcOH) to methyl 5-acetamido-4,7,8,9-tetra-0-acetyI-2,6-anhy-dro-2,3,5-trideoxy-D- /ycm>D- a/arto-non-2-enopyranosate. Compound 592 was found to be a potent neuraminidase inhibitor. 

A cyclic nucleotide, 2, 3 -bis(2-chloroethyl)aminophosphoryl-3 -amino-3 -deoxyadenosine (139) showing antitumor activity, was prepared in 40% yield starting from 3 -amino-3 -deoxyadenosine 133 by its phosphorylation with N,N-bis-(2-chloroethyl) amidophosphoryl dichloride 138. Both P-diastcrcomers separated by column chromatography exhibit activity against KB tumor cell cultures (Scheme 40) [71]. 

Representatives of the l-benzylidene-[l,4]oxazino[3,4- ]quinazolin-6-ones prepared from 315 exhibit remarkable protein-tyrosine kinase inhibitory activity and inhibit the growth of tumor cells <1996BMC547, 2001USP6331555, 2002BBA318>. 

The phorbol esters are useful for studying the function of PKC since they mimic the stimulatory effects of DAG on the enzyme. These tumor-promoting plant products and their synthetic derivatives are able to penetrate intact cells. Many inferences regarding the intracellular actions of PKC are based on results of studies on whole-cell preparations with the phorbol esters. These substances, like DAG, may produce feedback inhibition of signal transduction at a number of metabolic levels. Results of experiments using phorbol esters in whole cells are thus often complex and must be interpreted cautiously. Notwithstanding this consideration, based upon... 

Polymeric vesicles could be of better use for such an antitumor therapy on a cellular level, since they have at least one of the properties required, namely an extraordinary membrane stability. For a successful application, however, the simple systems prepared so far must be varied to a great extent, because the stability of a model cell membrane is not the only condition to be fulfilled. Besides stability and possibilities for cell recognition as discussed above the presence of cell membrane destructing substances such as lysophospholipids is necessary. These could e.g. be incorporated into the membrane of stabilized liposomes without destruction of the polymeric vesicles. There have already been reports about thekilling of tumor cells by synthetic alkyl lysophospholipids (72). 

Farnesylamine (123) (Fig. 20), a sesquiterpene alkaloid, was recently detected in whole extracts of Monomorium fieldi [129]. This compound had already be prepared by synthesis and found to display a whole range of biological activities. Among others, it inhibits arthropod molting, squalene synthesis, and the growth of malignant tumor cells, modulates human T cells and has anti-osteo-porosis activity [129]. 

While the FDA is adopting a cautious approach to cancer vaccine, such as DCVax-Brain, the Swiss Institute of Public Health has conditionally allowed the use of this vaccine by patients. DCVax consists of a patient s dendritic cells that have been pulsed with antigens derived from a tumor cell lysate prepared from surgically resected glioblastoma (brain cancer) tissue. It was developed by a company in the United States but has not yet been approved by the FDA. 

The prophylactic antitumor efficiency was tested by injecting 12 mice twice in seven days with AVE 3 TRP-2 (10 pg TRP-2) and AVE 3 1826 CpG (1.3 pg CpG) intradermally the control group remained untreated. Seven days after the last immunization 2 x 10 B16 tumor cells in 200 pL HBSS were injected into the tail vein of each mouse. Twenty days after tumor inoculation, the animals were sacrificed and the metastases in the prepared lungs counted. As Table 2 shows, the liposomal vaccination has a significant effect on the tumor growth in comparison to untreated animals. This is also reflected by the visual appearance of the lungs (data not shown). 

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