Effects of cerulein on keratin 8 phosphorylation and perinuclear reorganization in pancreatic cancer cells: Involvement of downregulation of protein phosphatase 2A and alpha4

YdjC chitooligosaccharide deacetylase homolog induces keratin reorganization in lung cancer cells: involvement of interaction between YDJC and CDC16

Lung cancer is a fatal disease with a high mortality rate. The perinuclear reorganization of keratin 8 (K8) is an important biochemical phenomenon reflecting changes in the physical properties of metastatic cancer. However, there is not much of information about the regulatory molecules involved in phosphorylation and perinuclear reorganization of K8.

In this study, we investigated the role and molecular mechanisms of YdjC chitooligosaccha- ride deacetylase homolog (YDJC) in sphingosylphosphorylcholine (SPC)-induced phosphorylation and reorganization of K8, and migration and invasion (SPC-induced events). SPC induced expression of YDJC in a dose- and time-dependent manner. Gene silencing of YDJC suppressed SPC-induced events. YDJC overexpression induced the SPC-induced events. YDJC deacetylase dominant negative mutant (YDJCD13A) did not induce SPC-induced events. YDJC siRNA reduced ERK activation and overexpression of YDJC induced ERK activation. The siRNA of ERK1 or ERK2 suppressed YDJC-induced phosphorylation and reorganization of K8, and migration and invasion. Co-immunoprecipitation revealed that YDJC binds to CDC16. Interestingly, CDC16 siRNA induced SPC-induced events. Overexpression of CDC16 blocked SPC-induced events. KMPLOT analysis based on public microarray data revealed the poor prognosis of lung cancer patients with high expression of YDJC compared with patients with low expression of YDJC.

The collective results indicate that YDJC is involved in SPC-induced events in A549 lung cancer cells by interacting with CDC16. YDJC overexpression might be involved in the progression of lung cancer. These results also suggest that suppression of YDJC or boosting of CDC16 interaction with YDJC might be a novel way to prevent progression of lung cancer.

Novel involvement of RhebL1 in sphingosylphosphorylcholine-induced keratin phosphorylation and reorganization: Binding to and activation of AKT1

Sphingosylphosphorylcholine induces keratin phosphorylation and reorganization, and increases viscoelasticity of metastatic cancer cells such as PANC-1 cells. However, the mechanism involved in sphingosylphosphorylcholine-induced keratin phosphorylation and reorganization is largely unknown. Sphingosylphosphorylcholine dose- and time-dependently induces the expression of RhebL1. The involvement of RhebL1 in sphingosylphosphorylcholine-induced events including keratin 8 (K8) phosphorylation, reorganization, migration and invasion was examined. Gene silencing of RhebL1 suppressed the sphingosylphosphorylcholine-induced events and overexpression of RhebL1 enhanced those events even without sphingosylphosphorylcholine treatment. We examined whether the G protein function of RhebL1 induces K8 phosphorylation using constitutively active RhebL1Q64L and dominant negative RhebL1D60K. G protein activity of RhebL1 is involved in sphingosylphosphorylcholine-induced K8 phosphorylation. We found that RhebL1 binds and activates AKT1. G protein activity of RhebL1 is involved in the binding and activation of AKT1. MK2206 (AKT inhibitor) and gene silencing of AKT1 inhibited the sphingosylphosphorylcholine-induced events, whereas overexpression of activated-AKT1 induced K8 phosphorylation, reorganization, migration and invasion even without sphingosylphosphorylcholine treatment.

The collective results indicate that RhebL1 is involved in sphingosylphosphorylcholine-induced events in A549 lung cancer cells via binding to AKT1 leading to activation of it. These results suggest that suppression of RhebL1 or inhibition of RhebL1′s binding to AKT1 might be a novel way that prevents changes in the physical properties of metastatic cancer cells.