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Aberrant Wnt/β-catenin signaling and elevated expression of stem cell proteins are associated with osteosarcoma side population cells of high tumorigenicity.

Yi XJ, Zhao YH, Qiao LX, Jin CL, Tian J, Li QS - Mol Med Rep (2015)

Bottom Line: The results of subsequent western blot and reverse transcription‑quantitative polymerase chain reaction analyses revealed that the protein levels of β‑catenin and cyclin D1 were markedly upregulated in the fluorescence‑activated cell sorted osteosarcoma SP cells.In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct‑4, Sox‑2 and Nanog were significantly higher in the SP cells, which contributed to self‑renewal and enhanced the proliferation rate of the SP cells.Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/β‑catenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Traumatology, Linyi People's Hospital, Linyi, Shandong 276000, P.R. China.

ABSTRACT
According to the cancer stem cell theory, the presence of a small sub‑population of cancer cells, termed cancer stem cells (CSCs), have a significant implication on cancer treatment and are responsible for tumor recurrence. Previous studies have reported that alterations in the Wnt/β‑catenin signaling are crucial in the maintenance of CSCs. In the present study, the characteristic features and activation of Wnt/β‑catenin signaling in CSCs from osteosarcoma, an aggressive human bone tumor, were investigated. In total, ~2.1% of the cancer stem‑like side population (SP) cells were identified in the osteosarcoma samples. The results of subsequent western blot and reverse transcription‑quantitative polymerase chain reaction analyses revealed that the protein levels of β‑catenin and cyclin D1 were markedly upregulated in the fluorescence‑activated cell sorted osteosarcoma SP cells. In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct‑4, Sox‑2 and Nanog were significantly higher in the SP cells, which contributed to self‑renewal and enhanced the proliferation rate of the SP cells. Furthermore, the SP cells were found to be highly invasive and able to form tumors in vivo. Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/β‑catenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.

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Related in: MedlinePlus

Elevated Wnt/β-catenin signaling and stem cell proteins in SP cells. (A) Western blot analysis of protein expression in SP and non-SP cells. Equal quantities of protein were loaded in each lane. (B) Elevated expression levels of the Wnt target gene, CCND1, and stem cell genes, OCT-4, SOX2, nestin, CD133, Nanog SP and ABCG2 were detected using reverse transcription-quantitative polymerase chain reaction. Quantification was performed using data of three independent experiments. GAPDH was used as a housekeeping gene. Data are expressed as the mean ± standard deviation. **P<0.01 vs. non-SP cells. SP, side population.
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f3-mmr-12-04-5042: Elevated Wnt/β-catenin signaling and stem cell proteins in SP cells. (A) Western blot analysis of protein expression in SP and non-SP cells. Equal quantities of protein were loaded in each lane. (B) Elevated expression levels of the Wnt target gene, CCND1, and stem cell genes, OCT-4, SOX2, nestin, CD133, Nanog SP and ABCG2 were detected using reverse transcription-quantitative polymerase chain reaction. Quantification was performed using data of three independent experiments. GAPDH was used as a housekeeping gene. Data are expressed as the mean ± standard deviation. **P<0.01 vs. non-SP cells. SP, side population.

Mentions: Previous studies investigating different types of cancer have reported that hyperactivation of the Wnt/β-catenin pathway results in elevated expression levels of stem cell surface proteins and its downstream signaling pathways (22,23). Therefore, the presents study evaluated the activation of Wnt/β-catenin signaling and the expression of stemness genes in the in the FACS-sorted SP cells. Western blot analysis revealed that the protein level of β-catenin was higher in the SP cells, compared with the non-SP cells (Fig. 3A). Similarly, the expression of the ABCG2 ABC transporter protein was significantly higher in the SP cells. In addition, the results of the RT-qPCR analysis revealed that the relative mRNA expression levels of the wnt target gene cyclin D1, ABCG2 and stem cell genes, including CD133, nestin Oct-4, Sox-2 and Nanog were significantly elevated in the SP cells, compared with the non-SP cells (Fig. 3B). Therefore, these data suggested that elevated levels of Wnt/β-catenin signaling may be a trigger for the increased expression levels of ABCG2 and stem cell surface proteins, involved in multi-drug resistance and tumori-genic properties of the SP cells.


Aberrant Wnt/β-catenin signaling and elevated expression of stem cell proteins are associated with osteosarcoma side population cells of high tumorigenicity.

Yi XJ, Zhao YH, Qiao LX, Jin CL, Tian J, Li QS - Mol Med Rep (2015)

Elevated Wnt/β-catenin signaling and stem cell proteins in SP cells. (A) Western blot analysis of protein expression in SP and non-SP cells. Equal quantities of protein were loaded in each lane. (B) Elevated expression levels of the Wnt target gene, CCND1, and stem cell genes, OCT-4, SOX2, nestin, CD133, Nanog SP and ABCG2 were detected using reverse transcription-quantitative polymerase chain reaction. Quantification was performed using data of three independent experiments. GAPDH was used as a housekeeping gene. Data are expressed as the mean ± standard deviation. **P<0.01 vs. non-SP cells. SP, side population.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581745&req=5

f3-mmr-12-04-5042: Elevated Wnt/β-catenin signaling and stem cell proteins in SP cells. (A) Western blot analysis of protein expression in SP and non-SP cells. Equal quantities of protein were loaded in each lane. (B) Elevated expression levels of the Wnt target gene, CCND1, and stem cell genes, OCT-4, SOX2, nestin, CD133, Nanog SP and ABCG2 were detected using reverse transcription-quantitative polymerase chain reaction. Quantification was performed using data of three independent experiments. GAPDH was used as a housekeeping gene. Data are expressed as the mean ± standard deviation. **P<0.01 vs. non-SP cells. SP, side population.
Mentions: Previous studies investigating different types of cancer have reported that hyperactivation of the Wnt/β-catenin pathway results in elevated expression levels of stem cell surface proteins and its downstream signaling pathways (22,23). Therefore, the presents study evaluated the activation of Wnt/β-catenin signaling and the expression of stemness genes in the in the FACS-sorted SP cells. Western blot analysis revealed that the protein level of β-catenin was higher in the SP cells, compared with the non-SP cells (Fig. 3A). Similarly, the expression of the ABCG2 ABC transporter protein was significantly higher in the SP cells. In addition, the results of the RT-qPCR analysis revealed that the relative mRNA expression levels of the wnt target gene cyclin D1, ABCG2 and stem cell genes, including CD133, nestin Oct-4, Sox-2 and Nanog were significantly elevated in the SP cells, compared with the non-SP cells (Fig. 3B). Therefore, these data suggested that elevated levels of Wnt/β-catenin signaling may be a trigger for the increased expression levels of ABCG2 and stem cell surface proteins, involved in multi-drug resistance and tumori-genic properties of the SP cells.

Bottom Line: The results of subsequent western blot and reverse transcription‑quantitative polymerase chain reaction analyses revealed that the protein levels of β‑catenin and cyclin D1 were markedly upregulated in the fluorescence‑activated cell sorted osteosarcoma SP cells.In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct‑4, Sox‑2 and Nanog were significantly higher in the SP cells, which contributed to self‑renewal and enhanced the proliferation rate of the SP cells.Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/β‑catenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Traumatology, Linyi People's Hospital, Linyi, Shandong 276000, P.R. China.

ABSTRACT
According to the cancer stem cell theory, the presence of a small sub‑population of cancer cells, termed cancer stem cells (CSCs), have a significant implication on cancer treatment and are responsible for tumor recurrence. Previous studies have reported that alterations in the Wnt/β‑catenin signaling are crucial in the maintenance of CSCs. In the present study, the characteristic features and activation of Wnt/β‑catenin signaling in CSCs from osteosarcoma, an aggressive human bone tumor, were investigated. In total, ~2.1% of the cancer stem‑like side population (SP) cells were identified in the osteosarcoma samples. The results of subsequent western blot and reverse transcription‑quantitative polymerase chain reaction analyses revealed that the protein levels of β‑catenin and cyclin D1 were markedly upregulated in the fluorescence‑activated cell sorted osteosarcoma SP cells. In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct‑4, Sox‑2 and Nanog were significantly higher in the SP cells, which contributed to self‑renewal and enhanced the proliferation rate of the SP cells. Furthermore, the SP cells were found to be highly invasive and able to form tumors in vivo. Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/β‑catenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.

Show MeSH
Related in: MedlinePlus