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TGF-?-Induced Quiescence Mediates Chemoresistance of Tumor-Propagating Cells in Squamous Cell Carcinoma.

ABSTRACT: Squamous cell carcinomas (SCCs) are heterogeneous tumors sustained by tumor-propagating cancer cells (TPCs). SCCs frequently resist chemotherapy through still unknown mechanisms. Here, we combine H2B-GFP-based pulse-chasing with cell-surface markers to distinguish quiescent from proliferative TPCs within SCCs. We find that quiescent TPCs resist DNA damage and exhibit increased tumorigenic potential in response to chemotherapy, whereas proliferative TPCs undergo apoptosis. Quiescence is regulated by TGF-?/SMAD signaling, which directly regulates cell-cycle gene transcription to control a reversible G1 cell-cycle arrest, independent of p21CIP function. Indeed, genetic or pharmacological TGF-? inhibition increases the susceptibility of TPCs to chemotherapy because it prevents entry into a quiescent state. These findings provide direct evidence that TPCs can reversibly enter a quiescent, chemoresistant state and thereby underscore the need for combinatorial approaches to improve treatment of chemotherapy-resistant SCCs.

SUBMITTER: Brown JA

PROVIDER: S-EPMC5778452 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Publications

TGF-β-Induced Quiescence Mediates Chemoresistance of Tumor-Propagating Cells in Squamous Cell Carcinoma.

Brown Jessie A JA Yonekubo Yoshiya Y Hanson Nicole N Sastre-Perona Ana A Basin Alice A Rytlewski Julie A JA Dolgalev Igor I Meehan Shane S Tsirigos Aristotelis A Beronja Slobodan S Schober Markus M

Cell stem cell 20171101 5

Squamous cell carcinomas (SCCs) are heterogeneous tumors sustained by tumor-propagating cancer cells (TPCs). SCCs frequently resist chemotherapy through still unknown mechanisms. Here, we combine H2B-GFP-based pulse-chasing with cell-surface markers to distinguish quiescent from proliferative TPCs within SCCs. We find that quiescent TPCs resist DNA damage and exhibit increased tumorigenic potential in response to chemotherapy, whereas proliferative TPCs undergo apoptosis. Quiescence is regulated ...[more]

PMID: 29100014

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Project description:Oral tongue squamous cell carcinoma (OTSCC) is one of the most common head and neck cancers. Innate or acquired resistance to cisplatin, a standard chemotherapy agent for OTSCC, is common in patients with OTSCC. Understanding the molecular basis for cisplatin chemoresistance in OTSCC cells may serve as a basis for identification of novel therapeutic targets. Podocalyxin (PODXL) has been found critical for malignant progression in a variety of cancers. Bmi1 has recently been found to induce cell apoptosis and cisplatin chemosensitivity in OTSCC cells. In this study, we explored the interaction between PODXL and Bmi1 in OTSCC cells, and assessed its impact on OTSCC cell chemoresistance to cisplatin. PODXL and/or Bmi1 were stably overexpressed or knocked down in SCC-4 and Tca8113 human OTSCC cells. Overexpression of PODXL in both cell lines markedly elevated the expression level of Bmi1 and the half maximal inhibitory concentration (IC50) of cisplain and reduced cisplatin-induced cell apoptosis, which was abolished by knockdown of Bmi1 or a selective focal adhesion kinase (FAK) inhibitor. On the other hand, knockdown of PODXL significantly decreased the Bmi1 expression level and cisplatin IC50 and increased cisplatin-induced cell apoptosis, which was completely reversed by overexpression of Bmi1. While overexpression and knockdown of PODXL respectively increased and decreased the FAK activity, Bmi1 showed no significant effect on the FAK activity in OTSCC cells. In addition, overexpression of PODXL markedly elevated the stability of Bmi1 mRNA, which was abolished by a selective FAK inhibitor. In conclusion, this study provides the first evidence that PODXL up-regulates the expression level of Bmi1 in OTSCC cells by increasing the stability of Bmi1 mRNA through a FAK-dependent mechanism; this effect leads to enhanced cisplatin chemoresistance in OTSCC cells. This study adds new insights into the molecular mechanisms underlying OTSCC chemoresistance.

Dataset Information

TGF-?-Induced Quiescence Mediates Chemoresistance of Tumor-Propagating Cells in Squamous Cell Carcinoma.

Publications

TGF-β-Induced Quiescence Mediates Chemoresistance of Tumor-Propagating Cells in Squamous Cell Carcinoma.

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