Enhancement of anchorage‐independent growth of human pancreatic carcinoma MIA PaCa‐2 cells by signaling from protein kinase C to mitogen‐activated protein kinase

Abstract

We found that 12-O-tetradecanoylphorbol-13-acetate (TPA) promoted anchorage-independent growth but did not affect anchorage-dependent growth of MIA PaCa-2 human pancreatic carcinoma cells. TPA markedly activated mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase in an anchorage-independent manner. Two protein kinase C (PKC) isoforms, conventional PKC (cPKC) and novel PKC (nPKC), but not apical PKC, translocated from the cytosolic to the particulate fraction upon TPA treatment. To identify the PKC isoforms involved in the regulation of anchorage-independent growth, four PKC isoforms (alpha, delta, epsilon, and zeta) were forced to be expressed in MIA PaCa-2 cells with an adenovirus vector. Overexpression of nPKCdelta or nPKC epsilon activated MAPK and promoted anchorage-independent growth. Overexpression of cPKCalpha alone did not influence anchorage-independent growth but lowered the concentration of TPA that was required to enhance such growth. Expression of constitutively active MAPK kinase-1 (MEK1) also promoted anchorage-independent growth. Furthermore, PKC inhibitors or an MEK inhibitor completely suppressed both TPA-induced activation of MAPK and promotion of anchorage-independent growth, but a cPKC-selective inhibitor partially suppressed TPA-induced promotion of the growth. Based on these results, we suggest that MAPK activation, mediated by certain isoforms of PKC, plays a part in oncogenic growth of MIA PaCa-2 cells. In summary, our data indicated that specific inhibitors of the cPKC and nPKC signaling pathway might be selective anti-oncogenic growth agents for some types of human pancreatic cancer.

Information-theoretic analysis of phenotype changes in early stages of carcinogenesis

“…The transcripts of the group that is reduced in BP cells compared with L are essentially all within the noise limit. All these pathways contribute to anchorageindependent growth of transformed cells (19)(20)(21). As we have shown previously, BP cells are able to form colonies in soft agar.…”

Inhibitory Effects of 12-O-Tetradecanoylphorbol-13-acetate Alone or in Combination with All-transRetinoic Acid on the Growth of Cultured Human Pancreas Cancer Cells and Pancreas Tumor Xenografts in Immunodeficient Mice

“…Pretreatment of DanG pancreas cancer cells with GF109203X (bisindolylmaleimide I) prevented the growth inhibitory effect of TPA, and evidence was presented that TPA inhibited the growth of DanG cells by activation of PKC␣ (Detjen et al, 2000). In a more recent study, treatment of MIA PaCa-2 cells with TPA enhanced MAPK, and this treatment enhanced anchorage-independent growth of these cells growing in suspension, but these effects were not observed in attached cells (Ishino et al, 2002). The stimulatory effect of TPA on anchorage-independent growth of MIA PaCa-2 cells was inhibited by inhibitors of PKC and mitogenactivated protein kinase kinase, and overexpression of PKC␣, PKC␦, or PKC⑀ increased the phosphorylation of MAPK in suspended cells (Ishino et al, 2002).…”

“…In a more recent study, treatment of MIA PaCa-2 cells with TPA enhanced MAPK, and this treatment enhanced anchorage-independent growth of these cells growing in suspension, but these effects were not observed in attached cells (Ishino et al, 2002). The stimulatory effect of TPA on anchorage-independent growth of MIA PaCa-2 cells was inhibited by inhibitors of PKC and mitogenactivated protein kinase kinase, and overexpression of PKC␣, PKC␦, or PKC⑀ increased the phosphorylation of MAPK in suspended cells (Ishino et al, 2002). Overexpression of PKC␦ or PKC⑀ in MIA PaCa-2 cells also enhanced anchorage-independent growth by 30 to 50%, and overexpression of PKC␣ lowered the concentration of TPA that was needed to stimulate anchorage-independent growth (Ishino et al, 2002).…”

Selected Combination Therapy with Sorafenib: A Review of Clinical Data and Perspectives in Advanced Solid Tumors

“…Pancreatic cancer is associated with a high frequency of activating oncogenic k-ras mutations [60]. In addition, VEGF-A expression in pancreatic adenocarcinoma is associated with a greater likelihood of disease progression, poor prognosis, and a higher risk for metastatic spread [61,62].…”