Mol Cancer. 2010 Oct 27;9:283.

Elimination of head and neck cancer initiating cells through targeting glucose regulated protein78 signaling.

Wu MJ, Jan CI, Tsay YG, Yu YH, Huang CY, Lin SC, Liu CJ, Chen YS, Lo JF, Yu CC.

Source

Institute of Oral Biology, National Yang-Ming University, Taipei, Taiwan.

Abstract

BACKGROUND:

Head and neck squamous cell carcinoma (HNSCC) is a highly lethal cancer that contains cellular and functional heterogeneity. Previously, we enriched a subpopulation of highly tumorigenic head and neck cancer initiating cells (HN-CICs) from HNSCC. However, the molecular mechanisms by which to govern the characteristics of HN-CICs remain unclear. GRP78, a stress-inducible endoplasmic reticulum chaperone, has been reported to play a crucial role in the maintenance of embryonic stem cells, but the role of GRP78 in CICs has not been elucidated.

RESULTS:

Initially, we recognized GRP78 as a putative candidate on mediating the stemness and tumorigenic properties of HN-CICs by differential systemic analyses. Subsequently, cells with GRP78 anchored at the plasma membrane (memGRP78+) exerted cancer stemness properties of self-renewal, differentiation and radioresistance. Of note, xenotransplantation assay indicated merely 100 memGRP78+ HNSCCs resulted in tumor growth. Moreover, knockdown of GRP78 significantly reduced the self-renewal ability, side population cells and expression of stemness genes, but inversely promoted cell differentiation and apoptosis in HN-CICs. Targeting GRP78 also lessened tumorigenicity of HN-CICs both in vitro and in vivo. Clinically, co-expression of GRP78 and Nanog predicted the worse survival prognosis of HNSCC patients by immunohistochemical analyses. Finally, depletion of GRP78 in HN-CICs induced the expression of Bax, Caspase 3, and PTEN.

CONCLUSIONS:

In summary, memGRP78 should be a novel surface marker for isolation of HN-CICs, and targeting GRP78 signaling might be a potential therapeutic strategy for HNSCC through eliminating HN-CICs.

PMID:: 20979610; [PubMed - indexed for MEDLINE]
PMCID:: PMC2987982

Free PMC Article

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Figure 2

Cancer stem cells properties of ^memGRP78⁺and ^memGRP78^-HNSCCs in vitro and in vivo. (A) Expressions of pluripotent stemness genes (Oct4 and Nanog) in ^memGRP78⁺and ^memGRP78^-HNSCCs were determined by western analysis. The amount of GAPDH was referred as loading control. (B) Representative images of tumorsphere-forming ability in ^memGRP78⁺and ^memGRP78^-HNSCCs grown under defined serum-free selection medium as described at Materials and Methods. The numbers of spheres were further calculated using microscope. Results are means ± SD from three experiments. (**, p < 0.01) (C) Sorted ^memGRP78⁺and ^memGRP78^-cells were further cultivated with standard medium containing 10% serum. At day 10, the percentage of ^memGRP78 expression was re-analyzed by flow cytometry. (D) To elucidate the anchorage independent growth, single cells suspension of ^memGRP78⁺and ^memGRP78^-cells plated onto soft agar and analyzed. Results are means ± SD of triplicate samples from three experiments (**, p < 0.01) (E) Invasion ability of ^memGRP78⁺and ^memGRP78^-cells were plated onto transwell coated with matrigel and analyzed. Results are means ± SD of triplicate samples from three experiments (**, p < 0.01) (F) Increased radio-resistance properties (OECM1-R3 > OECM1-R2 > OECM1-R1 > parental OECM1) positively correlates ^memGRP78 expression in HNSCCs by FACS analysis. (*, p < 0.05) (G) Summary of the in vivo tumor growth ability of different numbers of ^memGRP78⁺and ^memGRP78^-cells examined by xenotransplantation analysis. (H) Representative tumor growth of ^memGRP78⁺and ^memGRP78^-HNSCCs was generated in the subcutaneous space of recipient nude mice (Yellow arrows: ^memGRP78⁺HNSCCs; Red arrows: ^memGRP78^-HNSCCs). (I) Tumor volume was measured after inoculation of ^memGRP78⁺and ^memGRP78^-HNSCCs in nude mice. Error bars correspond to SD (lower panel). (*, p < 0.05).

Elimination of head and neck cancer initiating cells through targeting glucose regulated protein78 signaling

Mol Cancer. Mol Cancer;9:283-283.