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Cleaved CD44 intracellular domain supports activation of stemness factors and promotes tumorigenesis of breast cancer.

Cho Y, Lee HW, Kang HG, Kim HY, Kim SJ, Chun KH - Oncotarget (2015)

Bottom Line: We have found that the overexpression of CD44ICD increased mammosphere formation in breast cancer cells.Interestingly, CD44ICD decreased the expression levels and nuclear localization of stemness factors, but overexpression of CD44ICD reversed these effects.We suggest that the prevention of cleavage and nuclear-translocation of CD44ICD is a potential target in treating breast cancer.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry & Molecular Biology, Yonsei University College of Medicine, Seodaemun-gu, Seoul 120-752, Korea.

ABSTRACT
CD44 plays a role in the progression of tumors and is expressed in cancer stem cells (CSCs). However, the mechanisms underlying the crosstalk of CD44 with stemness genes in CSC maintenance remains unclear. In this study, we demonstrated how the cleaved intracellular domain of CD44 (CD44ICD) activates stemness factors such as Nanog, Sox2 and Oct4, and contributes to the tumorigenesis of breast cancer. We have found that the overexpression of CD44ICD increased mammosphere formation in breast cancer cells. Treatment with a γ-secretase inhibitor (GSI), which blocks the cleavage of CD44ICD, interfered with mammosphere formation. Interestingly, CD44ICD decreased the expression levels and nuclear localization of stemness factors, but overexpression of CD44ICD reversed these effects. In addition, we showed that nuclear localization of CD44ICD is important for transcriptional activation of the stemness factors. Furthermore, CD44ICD-overexpressed cells exhibited strong tumorigenecity and greater metastatic potential than did the control cells or CD44-depleted cells in vivo in mice models. Taken together, it was supposed that CD44 promotes tumorigenesis through the interaction and nuclear-translocation of its intracellular domain and stemness factors. We suggest that the prevention of cleavage and nuclear-translocation of CD44ICD is a potential target in treating breast cancer.

No MeSH data available.


Related in: MedlinePlus

Overexpression of CD44ICD in CD44-depleted cells increases both the expression and nuclear-localization of the stemness factors, Nanog, Sox2, and Oct4Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control vector and with the full-length CD44 and CD44ICD expression vectors. CD44ICD transfected cells were treated with 5 μM of GSI for 24 hr. (A) The mRNA (upper) and protein levels (lower) of CD44 and stemness factors were detected with an RT-PCR and western blot analysis. (B) The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis. GAPDH and Lamin A/C were used as loading controls. (C) Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control and full-length form of CD44, and with the cleavage site truncated mutant CD44 vector. The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis.
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Figure 4: Overexpression of CD44ICD in CD44-depleted cells increases both the expression and nuclear-localization of the stemness factors, Nanog, Sox2, and Oct4Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control vector and with the full-length CD44 and CD44ICD expression vectors. CD44ICD transfected cells were treated with 5 μM of GSI for 24 hr. (A) The mRNA (upper) and protein levels (lower) of CD44 and stemness factors were detected with an RT-PCR and western blot analysis. (B) The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis. GAPDH and Lamin A/C were used as loading controls. (C) Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control and full-length form of CD44, and with the cleavage site truncated mutant CD44 vector. The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis.

Mentions: The overexpression of CD44ICD in CD44-depleted cells significantly increase the mRNA and protein expression levels of the stemness factors, which were similar to those in the cells with overexpression of full-length CD44 (Figure 4A). To detect the effect on another molecules by GSI, because GSI also blocks cleavage of other molecules, such as Notch and ErB-4 [19], we evaluated the effect of GSI on the nuclear localization of these stemness factors following CD44ICD overexpression (Figure 4A). Whereas GSI reduced the expression of these stemness factors, GSI did not affect the expression of the same stemness factors following overexpression of CD44ICD, suggesting that the GSI effect on the expression of stemness factor is dependent on CD44ICD.


Cleaved CD44 intracellular domain supports activation of stemness factors and promotes tumorigenesis of breast cancer.

Cho Y, Lee HW, Kang HG, Kim HY, Kim SJ, Chun KH - Oncotarget (2015)

Overexpression of CD44ICD in CD44-depleted cells increases both the expression and nuclear-localization of the stemness factors, Nanog, Sox2, and Oct4Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control vector and with the full-length CD44 and CD44ICD expression vectors. CD44ICD transfected cells were treated with 5 μM of GSI for 24 hr. (A) The mRNA (upper) and protein levels (lower) of CD44 and stemness factors were detected with an RT-PCR and western blot analysis. (B) The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis. GAPDH and Lamin A/C were used as loading controls. (C) Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control and full-length form of CD44, and with the cleavage site truncated mutant CD44 vector. The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 4: Overexpression of CD44ICD in CD44-depleted cells increases both the expression and nuclear-localization of the stemness factors, Nanog, Sox2, and Oct4Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control vector and with the full-length CD44 and CD44ICD expression vectors. CD44ICD transfected cells were treated with 5 μM of GSI for 24 hr. (A) The mRNA (upper) and protein levels (lower) of CD44 and stemness factors were detected with an RT-PCR and western blot analysis. (B) The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis. GAPDH and Lamin A/C were used as loading controls. (C) Endogenous CD44 stable knockdown MDA-MB-231 and MCF-7 cells were transfected with the control and full-length form of CD44, and with the cleavage site truncated mutant CD44 vector. The changes in the localization of CD44ICD and stemness factors were detected with a western blot analysis.
Mentions: The overexpression of CD44ICD in CD44-depleted cells significantly increase the mRNA and protein expression levels of the stemness factors, which were similar to those in the cells with overexpression of full-length CD44 (Figure 4A). To detect the effect on another molecules by GSI, because GSI also blocks cleavage of other molecules, such as Notch and ErB-4 [19], we evaluated the effect of GSI on the nuclear localization of these stemness factors following CD44ICD overexpression (Figure 4A). Whereas GSI reduced the expression of these stemness factors, GSI did not affect the expression of the same stemness factors following overexpression of CD44ICD, suggesting that the GSI effect on the expression of stemness factor is dependent on CD44ICD.

Bottom Line: We have found that the overexpression of CD44ICD increased mammosphere formation in breast cancer cells.Interestingly, CD44ICD decreased the expression levels and nuclear localization of stemness factors, but overexpression of CD44ICD reversed these effects.We suggest that the prevention of cleavage and nuclear-translocation of CD44ICD is a potential target in treating breast cancer.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry & Molecular Biology, Yonsei University College of Medicine, Seodaemun-gu, Seoul 120-752, Korea.

ABSTRACT
CD44 plays a role in the progression of tumors and is expressed in cancer stem cells (CSCs). However, the mechanisms underlying the crosstalk of CD44 with stemness genes in CSC maintenance remains unclear. In this study, we demonstrated how the cleaved intracellular domain of CD44 (CD44ICD) activates stemness factors such as Nanog, Sox2 and Oct4, and contributes to the tumorigenesis of breast cancer. We have found that the overexpression of CD44ICD increased mammosphere formation in breast cancer cells. Treatment with a γ-secretase inhibitor (GSI), which blocks the cleavage of CD44ICD, interfered with mammosphere formation. Interestingly, CD44ICD decreased the expression levels and nuclear localization of stemness factors, but overexpression of CD44ICD reversed these effects. In addition, we showed that nuclear localization of CD44ICD is important for transcriptional activation of the stemness factors. Furthermore, CD44ICD-overexpressed cells exhibited strong tumorigenecity and greater metastatic potential than did the control cells or CD44-depleted cells in vivo in mice models. Taken together, it was supposed that CD44 promotes tumorigenesis through the interaction and nuclear-translocation of its intracellular domain and stemness factors. We suggest that the prevention of cleavage and nuclear-translocation of CD44ICD is a potential target in treating breast cancer.

No MeSH data available.


Related in: MedlinePlus