Journal Article

c-Kit mediates chemoresistance and tumor-initiating capacity of ovarian cancer cells through activation of Wnt/β-catenin–ATP-binding cassette G2 signaling

Lai, H-C, Wong, A S T, Ip, C K, Chau, W K, Mak, A S C

2013

Overview

Cisplatin and paclitaxel are standard chemotherapy for metastatic ovarian cancer, but with limited efficacy. Cancer stem/progenitor cells (or tumor-initiating cells, TICs) are hypothesized to be chemoresistant, and the existence of TICs in ovarian cancer has been previously demonstrated. However, the key signals and molecular events regulating the formation and expansion of ovarian tumor-initiating cells (OTICs) remain elusive. Here, we show that c-Kit is not just a marker of OTICs, but also a critical mediator of the phenotype that can be a viable target for the treatment of ovarian cancer. In contrast to non-OICs, c-Kit was overexpressed in OTICs. Moreover, the use of small interfering RNA to inhibit c-Kit expression markedly attenuated the number and size of OTIC subpopulations, inhibited the expression of stem cell markers and decreased the tumorigenic capabilities of OTICs. Imatinib (Gleevec), a clinical drug that blocks c-Kit kinase activity, also demonstrated its inhibition potency on OTICs. In addition, cisplatin/paclitaxel, which killed non-OTICs, with c-Kit knockdown or imatinib revealed that this was critically required for intervening ovarian cancer progression and recurrence in vitro and in xenograft tumors in vivo . Similar results were obtained with OTICs derived from ovarian carcinoma patients. Studies into the mechanisms suggest an important role for the activation of Wnt/β-catenin and ATP-binding cassette G2 downstream of c-Kit. The tumor-promoting microenvironment, such as hypoxia, could promote OTICs via upregulation of c-Kit expression. These results unravel an integral role for c-Kit in ovarian neoplastic processes and shed light on its mechanisms of action.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/67/1059/2326 / 631/67/1517/1709 / 631/80/86 / Animals / Antineoplastic Agents - pharmacology / Apoptosis / ATP Binding Cassette Transporter, Sub-Family G, Member 2 / ATP-Binding Cassette Transporters - metabolism / Benzamides - pharmacology / beta Catenin - metabolism / c-Kit protein / Cell activation / Cell Biology / Cell Hypoxia / Cell Line, Tumor / Cell Proliferation - drug effects / Cell Survival - drug effects / Cell Transformation, Neoplastic - genetics / Cell Transformation, Neoplastic - metabolism / Cellular signal transduction / Chemical properties / Chemoresistance / Chemotherapy / Cisplatin / Cisplatin - pharmacology / Development and progression / Drug Resistance, Neoplasm - genetics / Female / Gene Expression Regulation, Neoplastic / Genetic aspects / Health aspects / Human Genetics / Humans / Hypoxia / Imatinib / Imatinib Mesylate / Internal Medicine / Kinases / Medicine / Medicine & Public Health / Metastases / Mice / Mice, Inbred BALB C / Mice, Nude / Microenvironments / Neoplasm Proteins - metabolism / Neoplastic Stem Cells - drug effects / Neoplastic Stem Cells - metabolism / Oncology / original-article / Ovarian cancer / Ovarian carcinoma / Ovarian Neoplasms - drug therapy / Ovarian Neoplasms - metabolism / Ovarian Neoplasms - pathology / Paclitaxel / Paclitaxel - pharmacology / Phenotypes / Piperazines - pharmacology / Progenitor cells / Protein Kinase Inhibitors - pharmacology / Protein-tyrosine kinase / Proto-Oncogene Proteins c-kit - genetics / Proto-Oncogene Proteins c-kit - metabolism / Pyrimidines - pharmacology / Risk factors / RNA Interference / RNA, Small Interfering / siRNA / Stem cells / Tumor Microenvironment / Wnt protein / Wnt Proteins - metabolism / Wnt Signaling Pathway - drug effects / Xenograft Model Antitumor Assays / Xenografts / β-Catenin