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Overexpression and small molecule-triggered downregulation of CIP2A in lung cancer.

Ma L, Wen ZS, Liu Z, Hu Z, Ma J, Chen XQ, Liu YQ, Pu JX, Xiao WL, Sun HD, Zhou GB - PLoS ONE (2011)

Bottom Line: Cancerous inhibitor of PP2A (CIP2A) is a human oncoprotein inhibiting PP2A in many human malignancies.CIP2A overexpression was associated with cigarette smoking.Intriguingly, we found a natural compound, rabdocoetsin B which is extracted from a Traditional Chinese Medicinal herb Rabdosia coetsa, could induce down-regulation of CIP2A and inactivation of Akt pathway, and inhibit proliferation and induce apoptosis in a variety of lung cancer cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Carcinogenesis and Targeted Therapy for Cancer, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

ABSTRACT

Background: Lung cancer is the leading cause of cancer deaths worldwide, with a five-year overall survival rate of only 15%. Cancerous inhibitor of PP2A (CIP2A) is a human oncoprotein inhibiting PP2A in many human malignancies. However, whether CIP2A can be a new drug target for lung cancer is largely unclear.

Methodology/principal findings: Normal and malignant lung tissues were derived from 60 lung cancer patients from southern China. RT-PCR, Western blotting and immunohistochemistry were used to evaluate the expression of CIP2A. We found that among the 60 patients, CIP2A was undetectable or very low in paratumor normal tissues, but was dramatically elevated in tumor samples in 38 (63.3%) patients. CIP2A overexpression was associated with cigarette smoking. Silencing CIP2A by siRNA inhibited the proliferation and clonogenic activity of lung cancer cells. Intriguingly, we found a natural compound, rabdocoetsin B which is extracted from a Traditional Chinese Medicinal herb Rabdosia coetsa, could induce down-regulation of CIP2A and inactivation of Akt pathway, and inhibit proliferation and induce apoptosis in a variety of lung cancer cells.

Conclusions/significance: Our findings strongly indicate that CIP2A could be an effective target for lung cancer drug development, and the therapeutic potentials of CIP2A-targeting agents warrant further investigation.

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Related in: MedlinePlus

CIP2A is required for lung cancer cells' growth and transformation.(A): Western blot analysis of CIP2A protein expression in A549 cells 72 h after transfection with negative control (NC) or CIP2A-specific siRNA. (B and C): Flat plate clone formation assay for the clonogenic activity of A549 cells 72 h after transfection with NC or CIP2A-specific siRNA. (B): representative light miscroscopy images. (C): Quantitation of foci counting. Shown is mean+SD of four independent experiments. (D and E): Soft-agar colony formation assay for A549 cells transfected with NC or CIP2A-specific siRNA. (D): representative light miscroscopy images. (E): Quantitation of foci counting. (F): Western blot analysis of CIP2A protein in A549 cells transfected with NC or CIP2A-specific siRNA for 72 h. (G): Nude mice injected subcutaneously with A549 cells transfected with NC or CIP2A-specific siRNA. (H): The tumor growth curve for the experiment shown in (G). Shown is mean+SD of the mean tumor volumes. (I) Image of xenograft tumors obtained from mice shown in (G). * p<0.01, Student's t test.
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pone-0020159-g003: CIP2A is required for lung cancer cells' growth and transformation.(A): Western blot analysis of CIP2A protein expression in A549 cells 72 h after transfection with negative control (NC) or CIP2A-specific siRNA. (B and C): Flat plate clone formation assay for the clonogenic activity of A549 cells 72 h after transfection with NC or CIP2A-specific siRNA. (B): representative light miscroscopy images. (C): Quantitation of foci counting. Shown is mean+SD of four independent experiments. (D and E): Soft-agar colony formation assay for A549 cells transfected with NC or CIP2A-specific siRNA. (D): representative light miscroscopy images. (E): Quantitation of foci counting. (F): Western blot analysis of CIP2A protein in A549 cells transfected with NC or CIP2A-specific siRNA for 72 h. (G): Nude mice injected subcutaneously with A549 cells transfected with NC or CIP2A-specific siRNA. (H): The tumor growth curve for the experiment shown in (G). Shown is mean+SD of the mean tumor volumes. (I) Image of xenograft tumors obtained from mice shown in (G). * p<0.01, Student's t test.

Mentions: CIP2A specific siRNA was employed to evaluate its roles in lung cancer pathogenesis, and the results showed that as compared to negative control (NC), CIP2A silencing (Figure 3A) led to inhibition of clonogenic activity of A549 cells, detected by foci formation (Figure 3, B and C) and soft agar colony formation (Figure 3, D and E) assays [3]. These phenomena were confirmed by results of CIP2A silencing in L78 cells (Figure S1, A through E). Next, A549 cells were transfected with NC or CIP2A-specific siRNA (Figure 3F), and injected subcutaneously into the right and left flanks of 8 nude mice respectively, and tumor volumes were estimated every two days [12]. Interestingly, CIP2A-specific siRNA significantly inhibited tumor growth as compared to NC-siRNA (Figure 3, G through I). Together, these data indicate that CIP2A is essential to lung cancer proliferation and tumorigenesis, and could be an effective therapeutic target.


Overexpression and small molecule-triggered downregulation of CIP2A in lung cancer.

Ma L, Wen ZS, Liu Z, Hu Z, Ma J, Chen XQ, Liu YQ, Pu JX, Xiao WL, Sun HD, Zhou GB - PLoS ONE (2011)

CIP2A is required for lung cancer cells' growth and transformation.(A): Western blot analysis of CIP2A protein expression in A549 cells 72 h after transfection with negative control (NC) or CIP2A-specific siRNA. (B and C): Flat plate clone formation assay for the clonogenic activity of A549 cells 72 h after transfection with NC or CIP2A-specific siRNA. (B): representative light miscroscopy images. (C): Quantitation of foci counting. Shown is mean+SD of four independent experiments. (D and E): Soft-agar colony formation assay for A549 cells transfected with NC or CIP2A-specific siRNA. (D): representative light miscroscopy images. (E): Quantitation of foci counting. (F): Western blot analysis of CIP2A protein in A549 cells transfected with NC or CIP2A-specific siRNA for 72 h. (G): Nude mice injected subcutaneously with A549 cells transfected with NC or CIP2A-specific siRNA. (H): The tumor growth curve for the experiment shown in (G). Shown is mean+SD of the mean tumor volumes. (I) Image of xenograft tumors obtained from mice shown in (G). * p<0.01, Student's t test.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105001&req=5

pone-0020159-g003: CIP2A is required for lung cancer cells' growth and transformation.(A): Western blot analysis of CIP2A protein expression in A549 cells 72 h after transfection with negative control (NC) or CIP2A-specific siRNA. (B and C): Flat plate clone formation assay for the clonogenic activity of A549 cells 72 h after transfection with NC or CIP2A-specific siRNA. (B): representative light miscroscopy images. (C): Quantitation of foci counting. Shown is mean+SD of four independent experiments. (D and E): Soft-agar colony formation assay for A549 cells transfected with NC or CIP2A-specific siRNA. (D): representative light miscroscopy images. (E): Quantitation of foci counting. (F): Western blot analysis of CIP2A protein in A549 cells transfected with NC or CIP2A-specific siRNA for 72 h. (G): Nude mice injected subcutaneously with A549 cells transfected with NC or CIP2A-specific siRNA. (H): The tumor growth curve for the experiment shown in (G). Shown is mean+SD of the mean tumor volumes. (I) Image of xenograft tumors obtained from mice shown in (G). * p<0.01, Student's t test.
Mentions: CIP2A specific siRNA was employed to evaluate its roles in lung cancer pathogenesis, and the results showed that as compared to negative control (NC), CIP2A silencing (Figure 3A) led to inhibition of clonogenic activity of A549 cells, detected by foci formation (Figure 3, B and C) and soft agar colony formation (Figure 3, D and E) assays [3]. These phenomena were confirmed by results of CIP2A silencing in L78 cells (Figure S1, A through E). Next, A549 cells were transfected with NC or CIP2A-specific siRNA (Figure 3F), and injected subcutaneously into the right and left flanks of 8 nude mice respectively, and tumor volumes were estimated every two days [12]. Interestingly, CIP2A-specific siRNA significantly inhibited tumor growth as compared to NC-siRNA (Figure 3, G through I). Together, these data indicate that CIP2A is essential to lung cancer proliferation and tumorigenesis, and could be an effective therapeutic target.

Bottom Line: Cancerous inhibitor of PP2A (CIP2A) is a human oncoprotein inhibiting PP2A in many human malignancies.CIP2A overexpression was associated with cigarette smoking.Intriguingly, we found a natural compound, rabdocoetsin B which is extracted from a Traditional Chinese Medicinal herb Rabdosia coetsa, could induce down-regulation of CIP2A and inactivation of Akt pathway, and inhibit proliferation and induce apoptosis in a variety of lung cancer cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Carcinogenesis and Targeted Therapy for Cancer, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

ABSTRACT

Background: Lung cancer is the leading cause of cancer deaths worldwide, with a five-year overall survival rate of only 15%. Cancerous inhibitor of PP2A (CIP2A) is a human oncoprotein inhibiting PP2A in many human malignancies. However, whether CIP2A can be a new drug target for lung cancer is largely unclear.

Methodology/principal findings: Normal and malignant lung tissues were derived from 60 lung cancer patients from southern China. RT-PCR, Western blotting and immunohistochemistry were used to evaluate the expression of CIP2A. We found that among the 60 patients, CIP2A was undetectable or very low in paratumor normal tissues, but was dramatically elevated in tumor samples in 38 (63.3%) patients. CIP2A overexpression was associated with cigarette smoking. Silencing CIP2A by siRNA inhibited the proliferation and clonogenic activity of lung cancer cells. Intriguingly, we found a natural compound, rabdocoetsin B which is extracted from a Traditional Chinese Medicinal herb Rabdosia coetsa, could induce down-regulation of CIP2A and inactivation of Akt pathway, and inhibit proliferation and induce apoptosis in a variety of lung cancer cells.

Conclusions/significance: Our findings strongly indicate that CIP2A could be an effective target for lung cancer drug development, and the therapeutic potentials of CIP2A-targeting agents warrant further investigation.

Show MeSH
Related in: MedlinePlus