Anoikis-resistant cholangiocarcinoma cells display aggressive characteristics and increase STAT3 activation

Anoikis is a specialized cell apoptosis triggered by loss of cell adhesion. Acquisition of anoikis resistance is a key cancer hallmark that has been associated with metastasis of human malignancies. Cholangiocarcinoma (CCA) is a highly metastatic cancer of the bile duct, in which mechanisms underlying its resistance to anoikis has not been well elucidated.

HuCCT1 and Huh28 were utilized as in vitro models to examine biological characteristics of anoikis resistant-CCA cells. Expression and activation of signaling molecules were determined by western blotting.

We demonstrated that a significant proportion of CCA cells including HuCCT1 and Huh28 resisted anoikis induced by anchorage-independent condition. Notably, anoikis-resistant CCA cells, especially HuCCT1, substantially increased invasive potential and became resistant to gemcitabine, which is the standard chemotherapeutic agent for CCA. Mechanistically, the anoikis-resistant HuCCT1 cells markedly increased activation of signal transducer and activator of transcription 3 (STAT3) and concomitantly upregulated anti-apoptotic proteins, Mcl-1 and Bcl-2. Inhibition of STAT3 by AG 490 significantly induced HuCCT1 cells to undergo anoikis.

Taken together, our findings uncover the aggressive properties of CCA cells that overcome anoikis, and reveal the involvement of STAT3 signaling pathway in anoikis resistance in CCA. Targeting STAT3 may restore anoikis and prevent metastasis of the disease.