c-Kit mediates chemoresistance and tumor-initiating capacity of ovarian cancer cells through activation of Wnt/β-catenin-ATP-binding cassette G2 signaling.
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.
School of Biological Sciences, University of Hong Kong, HK, Hong Kong.
W K
WK
Chau
C K
CK
Ip
A S C
AS
Mak
H-C
HC
Lai
A S T
AS
Wong
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001549:Benzamides / Q000494:pharmacology*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000068877:Imatinib Mesylate; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D017239:Paclitaxel / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000494:pharmacology*; D034622:RNA Interference; D034741:RNA, Small Interfering; D059016:Tumor Microenvironment; D051153:Wnt Proteins / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays; D051176:beta Catenin / Q000378:metabolism
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D001549:Benzamides; D009363:Neoplasm Proteins; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D034741:RNA, Small Interfering; D051153:Wnt Proteins; D051176:beta Catenin; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit; D017239:Paclitaxel; D002945:Cisplatin