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KIAA1114, a full-length protein encoded by the trophinin gene, is a novel surface marker for isolating tumor-initiating cells of multiple hepatocellular carcinoma subtypes.

Kim SW, Yang HG, Kang MC, Lee S, Namkoong H, Lee SW, Sung YC - Oncotarget (2014)

Bottom Line: Notably, KIAA1114 expression was strongly detected in primary hepatic tumor, but neither in the adjacent non-tumorous tissue from the same patient nor normal liver tissue.KIAA1114high cells isolated from HCC cell lines displayed TIC-like features with superior functional and phenotypic traits compared to their KIAA1114low counterparts, including tumorigenic abilities in xenotransplantation model, in vitro colony- and spheroid-forming capabilities, expression of stemness-associated genes, and migratory capacity.Our findings not only address the value of a novel antigen, KIAA1114, as a potential diagnostic factor of human liver cancer, but also as an independent biomarker for identifying TIC populations that could be broadly applied to the heterogeneous HCC subtypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea.

ABSTRACT
Identification of novel biomarkers for tumor-initiating cells (TICs) is of critical importance for developing diagnostic and therapeutic strategies against cancers. Here we identified the role of KIAA1114, a full-length translational product of the trophinin gene, as a distinctive marker for TICs in human liver cancer by developing a DNA vaccine-induced monoclonal antibody targeting the putative extracellular domain of KIAA1114. Compared with other established markers of liver TICs, KIAA1114 was unique in that its expression was detected in both alpha fetoprotein (AFP)-positive and AFP-negative hepatocellular carcinoma (HCC) cell lines with the expression levels of KIAA1114 being positively correlated to their tumorigenic potentials. Notably, KIAA1114 expression was strongly detected in primary hepatic tumor, but neither in the adjacent non-tumorous tissue from the same patient nor normal liver tissue. KIAA1114high cells isolated from HCC cell lines displayed TIC-like features with superior functional and phenotypic traits compared to their KIAA1114low counterparts, including tumorigenic abilities in xenotransplantation model, in vitro colony- and spheroid-forming capabilities, expression of stemness-associated genes, and migratory capacity. Our findings not only address the value of a novel antigen, KIAA1114, as a potential diagnostic factor of human liver cancer, but also as an independent biomarker for identifying TIC populations that could be broadly applied to the heterogeneous HCC subtypes.

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Overlapping expression between established liver TIC markers and KIAA1114Flow cytometric analysis of HCC cell lines stained with antibodies against CD133, EpCAM, CD90, CD24, and CD13 in conjunction with Kiatomab. The quadrant marker of each plot was set on the basis of respective isotype control staining.
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Figure 3: Overlapping expression between established liver TIC markers and KIAA1114Flow cytometric analysis of HCC cell lines stained with antibodies against CD133, EpCAM, CD90, CD24, and CD13 in conjunction with Kiatomab. The quadrant marker of each plot was set on the basis of respective isotype control staining.

Mentions: Positive correlation between tumorigenicity of HCC cell lines and expression level of TIC markers has been observed in earlier studies. For example, the expression of CD133, the first TIC marker identified in liver cancer, was markedly higher in HCC cell lines having tumor-initiating capabilities in vivo compared to those lacking such capacities [26]. Similar results were obtained with another TIC marker CD90, whose expression level was closely associated with tumorigenic as well as metastatic potential of liver cancer cell lines [25]. Based on these results, we hypothesized that KIAA1114 may also be used as a marker to isolate TIC population. To validate this, we first determined whether the expression pattern of KIAA1114 overlapped with those of known liver TIC markers in HCC cell lines (Figure 3). Differential expression of various TIC markers between AFP+ and AFP− cells was also evaluated, as previous studies have shown that distinct prognostic subtypes of HCCs displayed distinguishable levels of expression for stem/maturation markers, including CD133 and CD90 (Supplementary Table 2) [8]. Firstly, the expression of KIAA1114 clearly overlapped with that of CD133 and EpCAM, both of which were expressed in AFP+ HCC cell lines. The level of CD133 and EpCAM expression was associated with tumorigenic potentials of AFP+ cell lines in general, as more tumorigenic Hep3B and HuH7 cells displayed significantly higher expression of those markers while less tumorigenic HepG2 cells showed no apparent expression. Nonetheless, CD133 and EpCAM expressions did not distinguish HuH7 from Hep3B cells whose tumorigenic capacity was known to be inferior to the former. It was also important to note that both CD133 and EpCAM were not or minimally expressed by AFP− HCC cell lines. Conversely, CD90 expression was confined to AFP− cells, in which a fraction of CD90+ cells was co-localized with KIAA1114-expressing cells. Nevertheless, non-tumorigenic SNU475 cells expressed higher level of CD90 than highly tumorigenic SK-Hep-1 cells. CD24 is a recently discovered liver TIC marker whose expression was found to be upregulated in residual chemoresistant HCC xenograft tumors [27]. Although this previous study reported that CD24 was expressed in AFP+ cell lines, including Hep3B and HuH7, as well as in a AFP− cell line, HLE, our results revealed that only AFP+ HuH7 cells expressed significantly high level of CD24 and displayed discernible co-localization of CD24+ and KIAA1114-expressing cells. Accordingly, a definite correlation between the extent of CD24 expression and tumorigenic potentials of cell lines was only observed in AFP+ subtype. Lastly, flow cytometric analysis of CD13, a semiquiescent TIC marker regulating ROS-induced DNA damage [28], showed that its expression could be detected and overlapped with that of KIAA1114 in all cell lines tested, regardless of their AFP expression status. Yet, CD13 expression showed no correlation with tumorigenicity of HCC cell lines in any of the HCC subtypes. These findings suggest that KIAA1114 is a unique biomarker whose expression not only overlaps with diverse liver TIC markers, but also correlates with tumorigenic capacities of HCC cell lines in both AFP+ and AFP− subtypes.


KIAA1114, a full-length protein encoded by the trophinin gene, is a novel surface marker for isolating tumor-initiating cells of multiple hepatocellular carcinoma subtypes.

Kim SW, Yang HG, Kang MC, Lee S, Namkoong H, Lee SW, Sung YC - Oncotarget (2014)

Overlapping expression between established liver TIC markers and KIAA1114Flow cytometric analysis of HCC cell lines stained with antibodies against CD133, EpCAM, CD90, CD24, and CD13 in conjunction with Kiatomab. The quadrant marker of each plot was set on the basis of respective isotype control staining.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4012722&req=5

Figure 3: Overlapping expression between established liver TIC markers and KIAA1114Flow cytometric analysis of HCC cell lines stained with antibodies against CD133, EpCAM, CD90, CD24, and CD13 in conjunction with Kiatomab. The quadrant marker of each plot was set on the basis of respective isotype control staining.
Mentions: Positive correlation between tumorigenicity of HCC cell lines and expression level of TIC markers has been observed in earlier studies. For example, the expression of CD133, the first TIC marker identified in liver cancer, was markedly higher in HCC cell lines having tumor-initiating capabilities in vivo compared to those lacking such capacities [26]. Similar results were obtained with another TIC marker CD90, whose expression level was closely associated with tumorigenic as well as metastatic potential of liver cancer cell lines [25]. Based on these results, we hypothesized that KIAA1114 may also be used as a marker to isolate TIC population. To validate this, we first determined whether the expression pattern of KIAA1114 overlapped with those of known liver TIC markers in HCC cell lines (Figure 3). Differential expression of various TIC markers between AFP+ and AFP− cells was also evaluated, as previous studies have shown that distinct prognostic subtypes of HCCs displayed distinguishable levels of expression for stem/maturation markers, including CD133 and CD90 (Supplementary Table 2) [8]. Firstly, the expression of KIAA1114 clearly overlapped with that of CD133 and EpCAM, both of which were expressed in AFP+ HCC cell lines. The level of CD133 and EpCAM expression was associated with tumorigenic potentials of AFP+ cell lines in general, as more tumorigenic Hep3B and HuH7 cells displayed significantly higher expression of those markers while less tumorigenic HepG2 cells showed no apparent expression. Nonetheless, CD133 and EpCAM expressions did not distinguish HuH7 from Hep3B cells whose tumorigenic capacity was known to be inferior to the former. It was also important to note that both CD133 and EpCAM were not or minimally expressed by AFP− HCC cell lines. Conversely, CD90 expression was confined to AFP− cells, in which a fraction of CD90+ cells was co-localized with KIAA1114-expressing cells. Nevertheless, non-tumorigenic SNU475 cells expressed higher level of CD90 than highly tumorigenic SK-Hep-1 cells. CD24 is a recently discovered liver TIC marker whose expression was found to be upregulated in residual chemoresistant HCC xenograft tumors [27]. Although this previous study reported that CD24 was expressed in AFP+ cell lines, including Hep3B and HuH7, as well as in a AFP− cell line, HLE, our results revealed that only AFP+ HuH7 cells expressed significantly high level of CD24 and displayed discernible co-localization of CD24+ and KIAA1114-expressing cells. Accordingly, a definite correlation between the extent of CD24 expression and tumorigenic potentials of cell lines was only observed in AFP+ subtype. Lastly, flow cytometric analysis of CD13, a semiquiescent TIC marker regulating ROS-induced DNA damage [28], showed that its expression could be detected and overlapped with that of KIAA1114 in all cell lines tested, regardless of their AFP expression status. Yet, CD13 expression showed no correlation with tumorigenicity of HCC cell lines in any of the HCC subtypes. These findings suggest that KIAA1114 is a unique biomarker whose expression not only overlaps with diverse liver TIC markers, but also correlates with tumorigenic capacities of HCC cell lines in both AFP+ and AFP− subtypes.

Bottom Line: Notably, KIAA1114 expression was strongly detected in primary hepatic tumor, but neither in the adjacent non-tumorous tissue from the same patient nor normal liver tissue.KIAA1114high cells isolated from HCC cell lines displayed TIC-like features with superior functional and phenotypic traits compared to their KIAA1114low counterparts, including tumorigenic abilities in xenotransplantation model, in vitro colony- and spheroid-forming capabilities, expression of stemness-associated genes, and migratory capacity.Our findings not only address the value of a novel antigen, KIAA1114, as a potential diagnostic factor of human liver cancer, but also as an independent biomarker for identifying TIC populations that could be broadly applied to the heterogeneous HCC subtypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Republic of Korea.

ABSTRACT
Identification of novel biomarkers for tumor-initiating cells (TICs) is of critical importance for developing diagnostic and therapeutic strategies against cancers. Here we identified the role of KIAA1114, a full-length translational product of the trophinin gene, as a distinctive marker for TICs in human liver cancer by developing a DNA vaccine-induced monoclonal antibody targeting the putative extracellular domain of KIAA1114. Compared with other established markers of liver TICs, KIAA1114 was unique in that its expression was detected in both alpha fetoprotein (AFP)-positive and AFP-negative hepatocellular carcinoma (HCC) cell lines with the expression levels of KIAA1114 being positively correlated to their tumorigenic potentials. Notably, KIAA1114 expression was strongly detected in primary hepatic tumor, but neither in the adjacent non-tumorous tissue from the same patient nor normal liver tissue. KIAA1114high cells isolated from HCC cell lines displayed TIC-like features with superior functional and phenotypic traits compared to their KIAA1114low counterparts, including tumorigenic abilities in xenotransplantation model, in vitro colony- and spheroid-forming capabilities, expression of stemness-associated genes, and migratory capacity. Our findings not only address the value of a novel antigen, KIAA1114, as a potential diagnostic factor of human liver cancer, but also as an independent biomarker for identifying TIC populations that could be broadly applied to the heterogeneous HCC subtypes.

Show MeSH
Related in: MedlinePlus