Limits...
Knockdown of Akt sensitizes osteosarcoma cells to apoptosis induced by cisplatin treatment.

Zhang G, Li M, Zhu X, Bai Y, Yang C - Int J Mol Sci (2011)

Bottom Line: Reduced expression of Akt2 did not directly inhibit the growth rate of the transfected cells; however, it significantly increased their sensitivity to cisplatin.Knockdown of Akt2, together with cisplatin treatment, promoted the expression of p53 up-regulated modulator of apoptosis (PUMA).It is possible that the augmentation of cisplatin cytotoxicity may be mediated by PUMA activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, Changhai Hospital, Second Military Medical University, Shanghai 200433, China; E-Mails: Zhangguoyou7@gmail.com (G.Z.); zhgych@yahoo.com.cn (X.Z.); baiyushu@21cn.com (Y.B.); changwei_y@yahoo.com.cn (W.Y.).

ABSTRACT
Akt plays an important role in the inhibition of apoptosis induced by chemotherapy and other stimuli. We therefore investigated if knockdown of Akt2 promoted drug-induced apoptosis in cultured osteosarcoma cells in vitro. SAOS-2 cells were transfected with Akt2 siRNA. The sensitivity of the transformed cell line to the chemotherapeutic drug cisplatin was assessed. Reduced expression of Akt2 did not directly inhibit the growth rate of the transfected cells; however, it significantly increased their sensitivity to cisplatin. Knockdown of Akt2, together with cisplatin treatment, promoted the expression of p53 up-regulated modulator of apoptosis (PUMA). It is possible that the augmentation of cisplatin cytotoxicity may be mediated by PUMA activation. The results of this study suggest that knockdown of Akt2 expression may have therapeutic applications in enhancing the efficacy of chemotherapy in patients with osteosarcoma.

Show MeSH

Related in: MedlinePlus

Knockdown of Akt2 sensitizes SAOS-2 cells to chemotherapeutic agents. (A) Cytotoxicity of cisplatin in SAOS-2 cells, SAOS-2 cells transfected with Akt2-siRNA and SAOS-2 cells transfected with Akt-3m-siRNA. Cells were treated with cisplatin at the indicated concentrations for 48 h. Percent survival was determined using the MTT assay. Each point represents the mean ± SD (error bars) from three independent experiments (** P < 0.05, * P < 0.05 vs. control); (B) IC50 values for cisplatin in the different cell lines. The IC50 values were determined after 48 h of exposure to cisplatin and were defined as the concentration causing 50% growth inhibition in treated cells, compared to that in control cells. Values are means ± SD from at least three independent experiments (* P < 0.05 vs. control).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC3116170&req=5

f3-ijms-12-02994: Knockdown of Akt2 sensitizes SAOS-2 cells to chemotherapeutic agents. (A) Cytotoxicity of cisplatin in SAOS-2 cells, SAOS-2 cells transfected with Akt2-siRNA and SAOS-2 cells transfected with Akt-3m-siRNA. Cells were treated with cisplatin at the indicated concentrations for 48 h. Percent survival was determined using the MTT assay. Each point represents the mean ± SD (error bars) from three independent experiments (** P < 0.05, * P < 0.05 vs. control); (B) IC50 values for cisplatin in the different cell lines. The IC50 values were determined after 48 h of exposure to cisplatin and were defined as the concentration causing 50% growth inhibition in treated cells, compared to that in control cells. Values are means ± SD from at least three independent experiments (* P < 0.05 vs. control).

Mentions: Knockdown of Akt2 in SAOS-2 cells increased their susceptibility to cisplatin. Figure 3 shows the decrease in cell viability as a function of drug concentration following treatment with cisplatin for 48 h. Akt2-siRNA-transfected SAOS-2 cells were significantly more sensitive to cisplatin compared with both untransfected and Akt-3m-siRNA-transfected parent cells. The reduced survival of Akt2-siRNA-transfected SAOS-2 cells was most pronounced at low drug concentrations. There was no significant difference in survival between Akt-3m-siRNA-transfected cells and parent SAOS-2 cells (Figure 3A). The mean IC50 for cisplatin in Akt2-siRNA-transfected cells was 4.8 μM, compared to 41.4 μM for control cells (Figure 3B). This corresponds to a 9-fold increase in chemosensitivity.


Knockdown of Akt sensitizes osteosarcoma cells to apoptosis induced by cisplatin treatment.

Zhang G, Li M, Zhu X, Bai Y, Yang C - Int J Mol Sci (2011)

Knockdown of Akt2 sensitizes SAOS-2 cells to chemotherapeutic agents. (A) Cytotoxicity of cisplatin in SAOS-2 cells, SAOS-2 cells transfected with Akt2-siRNA and SAOS-2 cells transfected with Akt-3m-siRNA. Cells were treated with cisplatin at the indicated concentrations for 48 h. Percent survival was determined using the MTT assay. Each point represents the mean ± SD (error bars) from three independent experiments (** P < 0.05, * P < 0.05 vs. control); (B) IC50 values for cisplatin in the different cell lines. The IC50 values were determined after 48 h of exposure to cisplatin and were defined as the concentration causing 50% growth inhibition in treated cells, compared to that in control cells. Values are means ± SD from at least three independent experiments (* P < 0.05 vs. control).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3116170&req=5

f3-ijms-12-02994: Knockdown of Akt2 sensitizes SAOS-2 cells to chemotherapeutic agents. (A) Cytotoxicity of cisplatin in SAOS-2 cells, SAOS-2 cells transfected with Akt2-siRNA and SAOS-2 cells transfected with Akt-3m-siRNA. Cells were treated with cisplatin at the indicated concentrations for 48 h. Percent survival was determined using the MTT assay. Each point represents the mean ± SD (error bars) from three independent experiments (** P < 0.05, * P < 0.05 vs. control); (B) IC50 values for cisplatin in the different cell lines. The IC50 values were determined after 48 h of exposure to cisplatin and were defined as the concentration causing 50% growth inhibition in treated cells, compared to that in control cells. Values are means ± SD from at least three independent experiments (* P < 0.05 vs. control).
Mentions: Knockdown of Akt2 in SAOS-2 cells increased their susceptibility to cisplatin. Figure 3 shows the decrease in cell viability as a function of drug concentration following treatment with cisplatin for 48 h. Akt2-siRNA-transfected SAOS-2 cells were significantly more sensitive to cisplatin compared with both untransfected and Akt-3m-siRNA-transfected parent cells. The reduced survival of Akt2-siRNA-transfected SAOS-2 cells was most pronounced at low drug concentrations. There was no significant difference in survival between Akt-3m-siRNA-transfected cells and parent SAOS-2 cells (Figure 3A). The mean IC50 for cisplatin in Akt2-siRNA-transfected cells was 4.8 μM, compared to 41.4 μM for control cells (Figure 3B). This corresponds to a 9-fold increase in chemosensitivity.

Bottom Line: Reduced expression of Akt2 did not directly inhibit the growth rate of the transfected cells; however, it significantly increased their sensitivity to cisplatin.Knockdown of Akt2, together with cisplatin treatment, promoted the expression of p53 up-regulated modulator of apoptosis (PUMA).It is possible that the augmentation of cisplatin cytotoxicity may be mediated by PUMA activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, Changhai Hospital, Second Military Medical University, Shanghai 200433, China; E-Mails: Zhangguoyou7@gmail.com (G.Z.); zhgych@yahoo.com.cn (X.Z.); baiyushu@21cn.com (Y.B.); changwei_y@yahoo.com.cn (W.Y.).

ABSTRACT
Akt plays an important role in the inhibition of apoptosis induced by chemotherapy and other stimuli. We therefore investigated if knockdown of Akt2 promoted drug-induced apoptosis in cultured osteosarcoma cells in vitro. SAOS-2 cells were transfected with Akt2 siRNA. The sensitivity of the transformed cell line to the chemotherapeutic drug cisplatin was assessed. Reduced expression of Akt2 did not directly inhibit the growth rate of the transfected cells; however, it significantly increased their sensitivity to cisplatin. Knockdown of Akt2, together with cisplatin treatment, promoted the expression of p53 up-regulated modulator of apoptosis (PUMA). It is possible that the augmentation of cisplatin cytotoxicity may be mediated by PUMA activation. The results of this study suggest that knockdown of Akt2 expression may have therapeutic applications in enhancing the efficacy of chemotherapy in patients with osteosarcoma.

Show MeSH
Related in: MedlinePlus