Selective elimination of cancer cells by the adenovirus E4orf4 protein in a Drosophila cancer model: a new paradigm for cancer therapy.

The adenovirus (Ad) E4orf4 protein contributes to efficient progression of virus infection. When expressed alone E4orf4 induces p53- and caspase-independent cell-death, which is more effective in cancer cells than in normal cells in tissue culture. Cancer selectivity of E4orf4-induced cell-death may result from interference with various regulatory pathways that cancer cells are more dependent on, including DNA damage signaling and proliferation control. E4orf4 signaling is conserved in several organisms, including yeast, Drosophila, and mammalian cells, indicating that E4orf4-induced cell-death can be investigated in these model organisms. The Drosophila genetic model system has contributed significantly to the study of cancer and to identification of novel cancer therapeutics. Here, we used the fly model to investigate the ability of E4orf4 to eliminate cancer tissues in a whole organism with minimal damage to normal tissues. We show that E4orf4 dramatically inhibited tumorigenesis and rescued survival of flies carrying a variety of tumors, including highly aggressive and metastatic tumors in the fly brain and eye discs. Moreover, E4orf4 rescued the morphology of adult eyes containing scrib- cancer clones even when expressed at a much later stage than scrib elimination. The E4orf4 partner protein phosphatase 2A (PP2A) was required for inhibition of tumorigenesis by E4orf4 in the system described here, whereas another E4orf4 partner, Src kinase, provided only minimal contribution to this process. Our results suggest that E4orf4 is an effective anticancer agent and reveal a promising potential for E4orf4-based cancer treatments.

Mecanismos da toxidez de FGF2 em células malignas dependentes de Ras: bloqueio de divisão celular e estresse proteotóxco / Mechanisms of FGF2 toxicity in Ras-driven malignant cells cell division blockage and proteotoxic stress

FGF2 ( Fibroblast Growth Factor 2) é o membro fundador de uma grande família de fatores de crescimento proteícos. Sua atividade se dá através da ligação e ativação de receptores especificos da membrana (FGFRs) com atividade de tirosina quimase. No organismo adulto, a simalização de FGF2 está envolvida na indução de processos de sobrevivência, proliferação e diferenciação celular; além de cicatrização e angiogênese. Por atuar como um clássico fator de crescimento, a atividade de FGF2 está frequentemente implicada em mecanismos pró-tumorais....

FGF2 is the first member of a large family of peptide growth factors. It binds and activates specific membrane receptors ( FGFRs) belonging to a family of tyrosine kinase receptors (RTK). in adult organisms, FGF2 signaling is involved in the induction of cell surveillance, proliferation and differentation; and also wound healing and angiogenesis. FGF2 is a bona fide growth factor and, as such, it is often implicated in pro-tumor mechanisms...

GGTase-I deficiency reduces tumor formation and improves survival in mice with K-RAS-induced lung cancer.

Protein geranylgeranyltransferase type I (GGTase-I) is responsible for the posttranslational lipidation of CAAX proteins such as RHOA, RAC1, and cell division cycle 42 (CDC42). Inhibition of GGTase-I has been suggested as a strategy to treat cancer and a host of other diseases. Although several GGTase-I inhibitors (GGTIs) have been synthesized, they have very different properties, and the effects of GGTIs and GGTase-I deficiency are unclear. One concern is that inhibiting GGTase-I might lead to severe toxicity. In this study, we determined the effects of GGTase-I deficiency on cell viability and K-RAS-induced cancer development in mice. Inactivating the gene for the critical beta subunit of GGTase-I eliminated GGTase-I activity, disrupted the actin cytoskeleton, reduced cell migration, and blocked the proliferation of fibroblasts expressing oncogenic K-RAS. Moreover, the absence of GGTase-I activity reduced lung tumor formation, eliminated myeloproliferative phenotypes, and increased survival of mice in which expression of oncogenic K-RAS was switched on in lung cells and myeloid cells. Interestingly, several cell types remained viable in the absence of GGTase-I, and myelopoiesis appeared to function normally. These findings suggest that inhibiting GGTase-I may be a useful strategy to treat K-RAS-induced malignancies.