We have previously demonstrated that the responsiveness of multiple myeloma (MM) cells to interferon-alpha (IFN-α) stimulation is variable, with ah atypical growth response displayed by some cells. Here we report the ability of IFN-α to induce tyrosine phosphorylation of a 180 kDa band in the KAS-6/1 MM cell line, which is growth responsive to IFN-α. Further characterization demonstrated that this band corresponds to ErbB3. To our knowledge, this is the first report of ErbB3 expression in a cell type of the hematopoietic lineage. Although ErbB receptors have been shown to crosscommunicate with various other receptors, our results show for the first rime that the IFN-α receptor can crosscommunicate with ErbB3. To address the significance of these observations, we transfected ErbB3-negative DP-6 MM cells with ErbB3 and used siRNA to silence ErbB3 in the KAS-6/1 cell line. Although IFN-α transactivated ErbB3 in the DP-6 transfectants, it did not confer growth responsiveness to IFN-α. Interestingly, silencing ErbB3 expression in the KAS-6/1 cells decreased the overall growth response to IFN-α and to interleukin-6. These results suggest that ErbB3 expression alone does not uniquely confer IFN-α growth responsiveness, but instead may amplify proliferation rates in MM cells that have acquired atypical expression of this receptor.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Jun 5 2003|
- Multiple myeloma
ASJC Scopus subject areas
- Molecular Biology
- Cancer Research