Decreased proliferation of human melanoma cell lines caused by antisense RNA against translation factor eIF-4A1

Abstract

Control of translation initiation was recognised as a critical checkpoint for cell proliferation and tumorigenesis. In human melanoma cells, we have previously reported consistent overexpression of translation initiation factor eIF-4A1. Here, we investigated by transfection of antisense constructs its significance for the control of melanoma cell growth. The tetracyclineinducible expression system was established in melanoma cells, and three fragments of the 5'-, central-, and 3'-portion of the eIF-4A1 cDNA were subcloned in antisense and in sense orientation after a tetracycline inducible promoter. Significant proliferation decrease was obtained after transient transfection and induction of antisense RNA directed against the 5'-and the central portion (up to 10%), whereas, no effects were seen after induction of the 3'-fragment and the sense controls. Cell clones stably transfected with the central antisense fragment revealed after doxycycline induction reduced expression of endogeneous eIF-4A1 mRNA correlated with decreased proliferation rates (up to 6%). These data demonstrate the applicability of antisense strategies against translation factors in melanoma cells. Translation initiation factor eIF-4A1 contributes to the control of melanoma cell proliferation and may be taken into consideration when scheduling new therapeutic approaches targeting the translational control.

A Serial Analysis of Gene Expression (SAGE) Database Analysis of Chemosensitivity

“…There is much data indicating that a high level of cell division, measured by rapid incorporation of labeled DNA precursors (33) or the activation of cell cycle proteins (34), is correlated within a particular tumor type with a poor survival. In addition, studies of the expression of genes involved in protein synthesis suggest that a high level of protein synthesis is also associated with poor prognosis (35,36). However, it is also true that some studies in tumors for which effective chemotherapy is available have shown that the reverse is true, that cancers undergoing more rapid cell division have a greater potential for long-term survival after treatment.…”

Proteomic Analysis Reveals Hyperactivation of the Mammalian Target of Rapamycin Pathway in Neurofibromatosis 1–Associated Human and Mouse Brain Tumors

“…Translational regulation and control of ribosome biogenesis are vital cellular processes that directly impact on cell proliferation and growth. Activated RAS and AKT controls protein translation (29,30) and the combination of activated RAS and AKT has been shown to recruit specific growth-promoting mRNAs to polysomes in glial cells (31). Because we found that several proteins associated with protein translation were aberrantly expressed in Nf1À/À astrocytes, we sought to determine whether these protein expression changes were associated with an increase in the overall rate of protein synthesis.…”

The Akt of translational control

“…However, the functional role of eIF4G phosphorylation has not been reported yet. Elevated levels of the eIF4A helicase are detected in human melanoma and hepatoma cells (Eberle et al, 1997(Eberle et al, , 2002Shuda et al, 2000). Furthermore, a novel putative tumor suppressor, Pdcd4, has been characterized as an inhibitor of eIF4A activity and cap-dependent translation (Yang et al, 2003).…”