Cdc42 negatively regulates intrinsic migration of highly aggressive breast cancer cells

Abstract

The small GTPase Cdc42 has been implicated as an important regulator of cell migration. However, whether Cdc42 plays similar role in all cancer cells irrespective of metastatic potential remains poorly defined. Here, we show by using three different breast cancer cell lines with different metastatic potential, the role of Cdc42 in cell migration/invasion and its relationship with a number of downstream signaling pathways controlling cell migration. Small interfering RNA (siRNA)-mediated knockdown of Cdc42 in two highly metastatic breast cancer cell lines (MDA-MB-231 and C3L5) resulted in enhancement, whereas the same in moderately metastatic (Hs578T) cell line resulted in inhibition of intrinsic cellular migration/invasion. Furthermore, Cdc42 silencing in MDA-MB-231 and C3L5 but not Hs578T cells was shown to be accompanied by increased RhoA activity and phosphorylation of protein kinase C (PKC)-δ, extracellular signal regulated kinase1/2 (Erk1/2), and protein kinase A (PKA). Pharmacological inhibition of PKCδ, MEK-Erk1/2, or PKA was shown to inhibit migration of both control and Cdc42-silenced MDA-MB-231 cells. Furthermore, introduction of constitutively active Cdc42 was shown to decrease migration/invasion of MDA-MB-231 and C3L5 but increase migration/invasion of Hs578T cells. This decreased migration/invasion of MDA-MB-231 and C3L5 cells was also shown to be accompanied by the decrease in the phosphorylations of PKCδ, Erk1/2, and PKA. These results suggested that endogenous Cdc42 could exert a negative regulatory influence on intrinsic migration/invasion and some potentially relevant changes in phosphorylation of PKCδ, Erk1/2, and PKA of some aggressive breast cancer cells.

Inhibition of CDK-mediated phosphorylation of Smad3 results in decreased oncogenesis in triple negative breast cancer cells

“…Furthermore, additional factors contributing to cell migration have also shown disparate effects in TNBC, with the Rho family GTPase Cdc42 found to negatively regulate cell migration in MDA-MB-231 cells while having a pro-migratory effect in Hs578T cells. 27 In recognizing the complexity of Smad3 action, impacted by both canonical and noncanonical phosphorylation, the specific phospho-Smad3 status may also have a role in the metastatic phenotypes of TNBC. As such, increased levels of Smad3 phosphorylated in the linker region (pSmad3L) have been detected in invasive human colorectal and hepatocellular cancers when compared to non-cancerous tissues.…”

Phosphorylation of Cdc42 Effector Protein-4 (CEP4) by Protein Kinase C Promotes Motility of Human Breast Cells

“…Although principally known to promote cell polarity, Cdc42 was recently reported to suppress migration of breast cancer cells (33). This finding contrasts with the promotility effects of activated Rac1 (34).…”

Steady-State Acceptor Fluorescence Anisotropy Imaging under Evanescent Excitation for Visualisation of FRET at the Plasma Membrane

“…The additional spatial information provided insights about Cdc42 activation and underlined its clear inhibition. Furthermore, since Cdc42 has been associated with a migratory behaviour which seems to be dependent on the cell lines as recent studies have shown [40], this new technique could, given its fast acquisition rates, provide quantitative method to test the activation of Cdc42 and to associate it to a migratory or anti-migratory role depending on the cancer cell line.…”

“…We studied the activity of Cdc42, a member of the Rho GTPase subfamily, which regulates cellular functions such as cytoskeletal reorganization, cell division [34], signal transduction or vesicle trafficking [35]. Cdc42 plays a key role in cell motility as well as invasion and migration [36], [37], which are targeted processes involved in cancer disease [38]–[40]. Furthermore, Cdc42 over-activity has been associated to cancer [41]–[43], immune diseases [44] and neuronal disorders [45].…”