Suppression of c-ras transformation by GTPase-activating protein

Article Abstract:

Proto-oncogenes are normal cellular genes which are similar to the cancer-causing oncogenes found in some tumor viruses. One such gene, or more precisely, class of genes, is ras, which occurs in all species that have been examined. The ras genes play a role in normal cell growth, and are required for the transformation of cells by the oncogenes. Previous research has shown that the ras gene products bind the nucleotides guanine triphosphate (GTP) and guanine diphosphate (GDP). The Ras proteins are active when primarily GTP is bound and inactive when primarily GDP is bound. The Ras proteins slowly hydrolyze GTP to GDP, and thus any process which accelerates this hydrolysis is likely to increase the amount of GDP and hence favor the inactivation of Ras. Such a protein is GAP, which stands for GTPase-activating protein. The regulation of Ras by GAP was demonstrated using transfected cells. Cells with additional ras genes tend to be transformed is tissue culture; that is, they tend to behave more like tumor cells. When these cells are also transfected with the gene for GAP, the transformation of the cultured cells is suppressed. This turns out to be true only for c-ras, the normal, or cellular ras gene. When the same experiment is repeated using v-ras, the viral ras gene from a tumor virus, the additional GAP gene is powerless to influence the transformation. The results indicate that GAP seems to play a role in the regulation of normal ras function, and that v-ras may exert its transforming function by escaping from the regulation normally exercised by GAP. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Cancer genetics, Proto-oncogenes, Oncogenes, Ras genes

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A human colon cancer cell capable of initiating tumour growth in immunodeficient mice

Article Abstract:

The renal capsule transplantation is used in immunodeficient pre-irradiated non-obese diabetic (NOD)/severe-combined immunodeficient (SCID) mice in order to identify a human colon cancer-initiating cell (CC-IC). The identification of colon cancer stem cells that are different from the bulk tumour cells has supported the hierarchical organization of human colon cancer.

Canada, Diagnosis, Xenotransplantation, Colon cancer

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Survival pathways meet their end

Article Abstract:

The cancer cells do not die even after chemotherapy as they have an inbuilt urge to survive. Wendel and co-workers provide some alternatives to this chemotherapy to ensure successful treatment.

Care and treatment, Chemotherapy

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