Epithelial-to-mesenchymal transition and oncogenic Ras expression in resistance to the protein kinase Cbeta inhibitor enzastaurin in colon cancer cells.
Identifying molecular factors of sensitivity and resistance of cancer cells to enzastaurin, a drug inhibiting protein kinase C (PKC) beta, remains a major challenge to improve its clinical development. Investigating the cellular effects of enzastaurin in a panel of 20 human cancer cell lines, we found that most cells displaying oncogenic K-Ras mutations also display resistance to enzastaurin. Wild-type (WT) K-Ras cancer cells displaying high sensitivity to enzastaurin also expressed high mRNA levels of epithelial markers, such as E-cadherin (CDH1), and low mRNA expressions of mesenchymal markers, such as vimentin, N-cadherin (CDH2), and other genes frequently expressed in mesenchymal transition such as ZEB1, TWIST, SLUG, SNAIL, and TGFbeta. WT K-Ras enzastaurin-resistant cells also expressed high levels of mesenchymal markers. Based on this observation, the effects of enzastaurin were investigated in epithelial colon COLO205-S cells that expressed WT Ras/Raf and its derived COLO205-R mesenchymal counterpart selected for resistance to most PKC modulators and displaying oncogenic K-Ras (G13D/exon 2). In COLO205-S cells, inhibition of phosphorylated PKCbeta led to the inactivation of AKT and glycogen synthase kinase 3beta and was associated with apoptosis without significant effect on cell cycle progression. In COLO205-R cells, enzastaurin induced mainly necrosis at high concentrations. In COLO205-R cells, a strong activation of extracellular signal-regulated kinase 1/2 possibly due to oncogenic K-Ras was predominantly associated with transcription of potent antiapoptotic genes, such as BCL2, GADD45B, and CDKN1A, as well as the multidrug resistance gene ABCB1. From this study, colon cancer cells undergoing apoptosis under enzastaurin exposure seem to frequently express a WT Ras and an epithelial phenotype.
Serova
Maria
M
INSERM U728, RayLab, Beaujon University Hospital (AP-HP-Paris 7 Diderot), Clichy, France.
Astorgues-Xerri
Lucile
L
Bieche
Ivan
I
Albert
Sebastien
S
Vidaud
Michel
M
Benhadji
Karim A
KA
Emami
Shahin
S
Vidaud
Dominique
D
Hammel
Pascal
P
Theou-Anton
Nathalie
N
Gespach
Christian
C
Faivre
Sandrine
S
Raymond
Eric
E
D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002277:Carcinoma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D054337:Cell Dedifferentiation / Q000187:drug effects / Q000235:genetics; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D011905:Genes, ras / Q000235:genetics*; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology* / Q000627:therapeutic use; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000473:pathology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D064546:Protein Kinase C beta; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D007211:Indoles; D047428:Protein Kinase Inhibitors; D011493:Protein Kinase C; D064546:Protein Kinase C beta; C504878:enzastaurin