Oncogenic cell transformation

Continuous cell proliferation then results in tumor formation. In addition, tumor growth beyond a millimeter size is dependent on tumor blood vessel formation, and changes resulting in enhanced cell mobility and migration allow tumor cells to metastasize to distant body sites (72). 

The Study of Lung Cancer in Experimental Mouse Models 

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Schengrund, C.-L., Duff, R., and Rosenberg, A., 1974, Sialidase activity of oncogenic cells transformed by herpes simplex virus. Virology 53 595-599. 

RNA oncogenic vimses have an unusual enzyme, reverse transcriptase, which is capable of making DNA copies from an RNA template. Cells transformed by these retrovimses have been shown to possess DNA transcripts of the viral RNA. It appears that the transformahon from normal to malignant is associated with the acquisition by the cell of viral DNA. 

A unifying theme of the role of oncogene function in cell transformation is that the expression of the proto-oncogenes is normally tightly... 

Ral has attracted much interest in recent years, not least because it was demonstrated to mediate part of Ras function as described above. In contrast to Rap, which rather inhibits Ras signaling, Ral is part of one of the essential Ras-activated pathways. Moreover, it has proved to be acting in parallel with the Raf pathway in cell transformation induced by oncogenic Ras [37, 77]. The case of Ral demonstrates the complexity - and the incomplete knowledge and understanding - of signal transduction. Ral can also be activated by Rap mediated by Rif [103] and, alternatively, by binding of a calcium/calmodulin complex to the Ral C-terminus which obviously does not affect the nucleotide state of Ral [111]. 

Finally, inappropriate expression of nuclear transcription factors can lead to cell transformation. For example, the products of he,fos and myc proto-oncogenes are transcription factors that regulate the expression of proteins that promote progression through the cell cycle. Levels of the Fos and Myc proteins are tightly regulated in normal cells. Uncontrolled expression of these proteins leads to cell proliferation. 

Frykberg, L., S. Palmieri, H. Beug, T. Graf, M.J. Hayman, and B. Vennstrom, Transforming capacities of avian erythroblastosis virus mutants deleted in the erbA or erbB oncogenes. Cell, 1983. 32(1) 227-38. 

Levine, A.E. Chakrabarty, S. (1992) Response of FR3T3 cells transformed by Ha-ras oncogene and epidermal growth factor gene to differentiation induction by A A -dimethylformamide. Int. J. Cancer, 50, 653-658... 

She QB, Ma WY, Wang M, Kaji A, Ho CT, Dong Z. 2003. Inhibition of cell transformation by resveratrol and its derivatives Differential effects and mechanisms involved. Oncogene 22 2143-2150. 

Mouse cells transformed by various oncogenic agents had decreased levels of GM1 and more complex gangliosides compared to their normal counterparts (43,45). More recently, it has been reported that transformed hamster cells exposed to butyrate lost many of their transformed properties and acquired a more normal phenotype... 

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