A novel interplay between oncogenic PFTK1 protein kinase and tumor suppressor TAGLN2 in the control of liver cancer cell motility

Abstract

The PFTK1 gene encodes a cdc2-related serine/threonine protein kinase that has been shown to confer cell migratory properties in hepatocellular carcinoma (HCC). However, the prognostic value and biological mechanism by which PFTK1 promotes HCC motility remain largely unknown. Here, we showed from tissue microarray that common upregulations of PFTK1 in primary HCC tumors (n ¼ 133/180) correlated significantly with early age onset (p40 years), advance tumor grading and presence of microvascular invasion (Pp0.05). To understand downstream phosphorylated substrate(s) of PFTK1, phospho-proteins in PFTK1 expressing and knockdown Hep3B cells were profiled by two-dimensional-polyacrylamide gel electrophoresis mass spectrometric analysis. Protein identification of differential spots revealed b-actin (ACTB) and transgelin2 (TAGLN2) as the two most profound phosphorylated changes affected by PFTK1. We verified the presence of TAGLN2 serine phosphorylation and ACTB tyrosine phosphorylation. Moreover, reduced TAGLN2 and ACTB phosphorylations in PFTK1-suppressed Hep3B corresponded to distinct actin depolymerizations and marked inhibition on cell invasion and motility. Given that TAGLN2 is a tumor suppressor whose function has been ascribed in cancer metastasis, we examined if TAGLN2 is an intermediate substrate in the biological path of PFTK1. We showed in PFTK1-suppressed cells that knockdown of TAGLN2 over-rode the inhibitory effect on cell invasion and motility, and a recovery on actin polymerization was evident. Interestingly, we also found that unphosphorylated TAGLN2 in PFTK1-suppressed cells elicited strong actin-binding ability, a mechanism that possibly halts the actin cytoskeleton dynamics. Site-directed mutagenesis of TAGLN2 suggested that PFTK1 regulates the actinbinding affinity of TAGLN2 through the S83 and S163 residues, which if mutated can significantly affect HCC cell motility. Taken together, our data propose a novel, oncogene-tumor suppressor interplay, where oncogenic PFTK1 confers HCC cell motility through inactivating the actin-binding motile suppressing function of TAGLN2 via phosphorylation.

Roles of the canonical myomiRs miR-1, -133 and -206 in cell development and disease

“…Interestingly, TAGLN2 is a known tumor suppressor, yet its upregulated expression is associated with increased metastasis, and worse patient prognosis. This outcome may be related to findings in HCC where phosphorylation of TAGLN2 by PFTK1 (an oncogenic serine/threonine protein kinase) inactivates its actin-binding function, abrogating its suppression of cell motility [139] . Fur thermore, in mouse metaphase I oocytes after IGF1 treatment, miRNA133b was upregulated more than 30fold and target TAGLN2 was downregulated, stimulating growth and maturation of the oocytes [140] .…”

Increased TEAD4 expression and nuclear localization in colorectal cancer promote epithelial–mesenchymal transition and metastasis in a YAP-independent manner

“…Gene set enrichment analysis 8 also indicated that the TEAD4-regulated transcriptome in CRC cells is rich in mesenchymal-related genes and in genes participating in cell migration (Figure 3c). Among the genes identified by the microarray analysis as TEAD4 targets, LOX, 9 DKK1 10 CDK14, 11 and MSN 12 have previously been implicated in cancer metastasis. As assessed by real-time PCR, these genes were all downregulated after TEAD4 knockdown (Figure 3d).…”

Cyclin-dependent kinases

“…Cdk10 is a major determinant of resistance to endocrine therapy for breast cancer [62], and inhibition of Cdk12 confers sensitivity to inhibitors of poly (ADP-ribose) polymerases PARP1 and PARP2 [63]. Cdk14 confers motility advantages and metastatic potential in hepatocellular carcinoma motility and metastasis [64,65]. Finally, as indicated above, cyclin Y kinases regulate the Wnt pathway [31], providing new therapeutic opportunities that are yet to be explored.…”