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CXCR6, a newly defined biomarker of tissue-specific stem cell asymmetric self-renewal, identifies more aggressive human melanoma cancer stem cells.

Taghizadeh R, Noh M, Huh YH, Ciusani E, Sigalotti L, Maio M, Arosio B, Nicotra MR, Natali P, Sherley JL, La Porta CA - PLoS ONE (2010)

Bottom Line: A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells.We defined CXCR6 as a new biomarker for tissue-specific stem cell asymmetric self-renewal.CXCR6 identifies a more discrete subpopulation of cultured human melanoma cells with a more aggressive MCSC phenotype than cells selected on the basis of the ABCG2+ phenotype alone.

View Article: PubMed Central - PubMed

Affiliation: Programs in Regenerative Biology and Cancer Biology, Adult Stem Cell Technology Center, Boston Biomedical Research Institute, Watertown, Massachusetts, United States of America.

ABSTRACT

Background: A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells. Recent investigations of a variety of tumor types have shown that phenotypically identifiable and isolable subfractions of cells possess the tumor-forming ability. In the present paper, using two lineage-related human melanoma cell lines, primary melanoma line IGR39 and its metastatic derivative line IGR37, two main observations are reported. The first one is the first phenotypic evidence to support the origin of melanoma cancer stem cells (CSCs) from mutated tissue-specific stem cells; and the second one is the identification of a more aggressive subpopulation of CSCs in melanoma that are CXCR6+.

Methods/findings: We defined CXCR6 as a new biomarker for tissue-specific stem cell asymmetric self-renewal. Thus, the relationship between melanoma formation and ABCG2 and CXCR6 expression was investigated. Consistent with their non-metastatic character, unsorted IGR39 cells formed significantly smaller tumors than unsorted IGR37 cells. In addition, ABCG2+ cells produced tumors that had a 2-fold greater mass than tumors produced by unsorted cells or ABCG2- cells. CXCR6+ cells produced more aggressive tumors. CXCR6 identifies a more discrete subpopulation of cultured human melanoma cells with a more aggressive MCSC phenotype than cells selected on the basis of the ABCG2+ phenotype alone.

Conclusions/significance: The association of a more aggressive tumor phenotype with asymmetric self-renewal phenotype reveals a previously unrecognized aspect of tumor cell physiology. Namely, the retention of some tissue-specific stem cell attributes, like the ability to asymmetrically self-renew, impacts the natural history of human tumor development. Knowledge of this new aspect of tumor development and progression may provide new targets for cancer prevention and treatment.

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Flow cytometry detection and sorting of ABCG2+ subpopulations from cultures of human melanoma cell lines.Primary melanoma IGR39 cells and metastatic melanoma IGR37 cells were incubated with the indicated fluorescent FITC-conjugated antibodies and analyzed by flow cytometry as described in Materials and Methods. Y-axes, side scatter; x-axes, relative fluorescence intensity. Left panels, analyses with isotype (IgG) control antibodies; middle panels, analyses with anti-ABCG2 FITC-conjugated antibodies. After FACS isolation based on the indicated gate (blue outline), ABCG2+ sorted cells were reanalyzed to confirm enrichment (right panels). Numbers, percent of total evaluated cells.
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pone-0015183-g002: Flow cytometry detection and sorting of ABCG2+ subpopulations from cultures of human melanoma cell lines.Primary melanoma IGR39 cells and metastatic melanoma IGR37 cells were incubated with the indicated fluorescent FITC-conjugated antibodies and analyzed by flow cytometry as described in Materials and Methods. Y-axes, side scatter; x-axes, relative fluorescence intensity. Left panels, analyses with isotype (IgG) control antibodies; middle panels, analyses with anti-ABCG2 FITC-conjugated antibodies. After FACS isolation based on the indicated gate (blue outline), ABCG2+ sorted cells were reanalyzed to confirm enrichment (right panels). Numbers, percent of total evaluated cells.

Mentions: Respectively, ∼11% and ∼40% of cells in actively growing cultures of IGR37 and IGR39 had detectable expression for ABCG2 (Fig. 2). IGR37 and IGR39 cells were sorted into ABCG2+ and ABCG2- subpopulations and transplanted into NOD-SCID mice (n = 3 for each subpopulation evaluated). Unsorted cells were also injected into NOD-SCID mice (n = 3) for comparison. After two months, mice from all cohorts were sacrificed. Tumor masses were excised, imaged, weighed, and digested to isolate single cell suspensions for further analysis. As shown in Table 2 and Fig. 3, the transplantation of ABCG2+ IGR37 cells resulted in tumors with 2-fold greater mass on average compared to tumors that arose from ABCG2- cells (p<0.01). Interestingly, injection of unsorted IGR37 cells also result in smaller tumors than ABCG2+ cells that were statistically similar in sizes to tumors from ABCG2- cells (Fig. 3; Table 2). Unsorted IGR39 cells resulted in smaller tumor masses, compared to unsorted IGR37 cells (0.13 grams vs. 1.4 grams, respectively; p<0.01) 2 months after the injection of the cells (Table 1). ABCG2- sorted IGR39 cells did not exhibit any macroscopic masses at this timepoint (Table 2), while ABCG2+ IGR39 cells produced tumors with a 3.6-fold increased mass compared to unsorted IGR39 cells (Table 2; p<0.01).


CXCR6, a newly defined biomarker of tissue-specific stem cell asymmetric self-renewal, identifies more aggressive human melanoma cancer stem cells.

Taghizadeh R, Noh M, Huh YH, Ciusani E, Sigalotti L, Maio M, Arosio B, Nicotra MR, Natali P, Sherley JL, La Porta CA - PLoS ONE (2010)

Flow cytometry detection and sorting of ABCG2+ subpopulations from cultures of human melanoma cell lines.Primary melanoma IGR39 cells and metastatic melanoma IGR37 cells were incubated with the indicated fluorescent FITC-conjugated antibodies and analyzed by flow cytometry as described in Materials and Methods. Y-axes, side scatter; x-axes, relative fluorescence intensity. Left panels, analyses with isotype (IgG) control antibodies; middle panels, analyses with anti-ABCG2 FITC-conjugated antibodies. After FACS isolation based on the indicated gate (blue outline), ABCG2+ sorted cells were reanalyzed to confirm enrichment (right panels). Numbers, percent of total evaluated cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3008677&req=5

pone-0015183-g002: Flow cytometry detection and sorting of ABCG2+ subpopulations from cultures of human melanoma cell lines.Primary melanoma IGR39 cells and metastatic melanoma IGR37 cells were incubated with the indicated fluorescent FITC-conjugated antibodies and analyzed by flow cytometry as described in Materials and Methods. Y-axes, side scatter; x-axes, relative fluorescence intensity. Left panels, analyses with isotype (IgG) control antibodies; middle panels, analyses with anti-ABCG2 FITC-conjugated antibodies. After FACS isolation based on the indicated gate (blue outline), ABCG2+ sorted cells were reanalyzed to confirm enrichment (right panels). Numbers, percent of total evaluated cells.
Mentions: Respectively, ∼11% and ∼40% of cells in actively growing cultures of IGR37 and IGR39 had detectable expression for ABCG2 (Fig. 2). IGR37 and IGR39 cells were sorted into ABCG2+ and ABCG2- subpopulations and transplanted into NOD-SCID mice (n = 3 for each subpopulation evaluated). Unsorted cells were also injected into NOD-SCID mice (n = 3) for comparison. After two months, mice from all cohorts were sacrificed. Tumor masses were excised, imaged, weighed, and digested to isolate single cell suspensions for further analysis. As shown in Table 2 and Fig. 3, the transplantation of ABCG2+ IGR37 cells resulted in tumors with 2-fold greater mass on average compared to tumors that arose from ABCG2- cells (p<0.01). Interestingly, injection of unsorted IGR37 cells also result in smaller tumors than ABCG2+ cells that were statistically similar in sizes to tumors from ABCG2- cells (Fig. 3; Table 2). Unsorted IGR39 cells resulted in smaller tumor masses, compared to unsorted IGR37 cells (0.13 grams vs. 1.4 grams, respectively; p<0.01) 2 months after the injection of the cells (Table 1). ABCG2- sorted IGR39 cells did not exhibit any macroscopic masses at this timepoint (Table 2), while ABCG2+ IGR39 cells produced tumors with a 3.6-fold increased mass compared to unsorted IGR39 cells (Table 2; p<0.01).

Bottom Line: A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells.We defined CXCR6 as a new biomarker for tissue-specific stem cell asymmetric self-renewal.CXCR6 identifies a more discrete subpopulation of cultured human melanoma cells with a more aggressive MCSC phenotype than cells selected on the basis of the ABCG2+ phenotype alone.

View Article: PubMed Central - PubMed

Affiliation: Programs in Regenerative Biology and Cancer Biology, Adult Stem Cell Technology Center, Boston Biomedical Research Institute, Watertown, Massachusetts, United States of America.

ABSTRACT

Background: A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells. Recent investigations of a variety of tumor types have shown that phenotypically identifiable and isolable subfractions of cells possess the tumor-forming ability. In the present paper, using two lineage-related human melanoma cell lines, primary melanoma line IGR39 and its metastatic derivative line IGR37, two main observations are reported. The first one is the first phenotypic evidence to support the origin of melanoma cancer stem cells (CSCs) from mutated tissue-specific stem cells; and the second one is the identification of a more aggressive subpopulation of CSCs in melanoma that are CXCR6+.

Methods/findings: We defined CXCR6 as a new biomarker for tissue-specific stem cell asymmetric self-renewal. Thus, the relationship between melanoma formation and ABCG2 and CXCR6 expression was investigated. Consistent with their non-metastatic character, unsorted IGR39 cells formed significantly smaller tumors than unsorted IGR37 cells. In addition, ABCG2+ cells produced tumors that had a 2-fold greater mass than tumors produced by unsorted cells or ABCG2- cells. CXCR6+ cells produced more aggressive tumors. CXCR6 identifies a more discrete subpopulation of cultured human melanoma cells with a more aggressive MCSC phenotype than cells selected on the basis of the ABCG2+ phenotype alone.

Conclusions/significance: The association of a more aggressive tumor phenotype with asymmetric self-renewal phenotype reveals a previously unrecognized aspect of tumor cell physiology. Namely, the retention of some tissue-specific stem cell attributes, like the ability to asymmetrically self-renew, impacts the natural history of human tumor development. Knowledge of this new aspect of tumor development and progression may provide new targets for cancer prevention and treatment.

Show MeSH
Related in: MedlinePlus