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Molecular targeting of the oncoprotein PLK1 in pediatric acute myeloid leukemia: RO3280, a novel PLK1 inhibitor, induces apoptosis in leukemia cells.

Wang NN, Li ZH, Zhao H, Tao YF, Xu LX, Lu J, Cao L, Du XJ, Sun LC, Zhao WL, Xiao PF, Fang F, Su GH, Li YH, Li G, Li YP, Xu YY, Zhou HT, Wu Y, Jin MF, Liu L, Ni J, Wang J, Hu SY, Zhu XM, Feng X, Pan J - Int J Mol Sci (2015)

Bottom Line: PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001).RO3280 treatment regulated several apoptosis-associated genes.These results provide insights into the potential use of RO3280 for AML therapy; however, the underlying mechanisms remain to be determined.

View Article: PubMed Central - PubMed

Affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou 215003, China. wangnn90s@163.com.

ABSTRACT
Polo-like kinase 1 (PLK1) is highly expressed in many cancers and therefore a biomarker of transformation and potential target for the development of cancer-specific small molecule drugs. RO3280 was recently identified as a novel PLK1 inhibitor; however its therapeutic effects in leukemia treatment are still unknown. We found that the PLK1 protein was highly expressed in leukemia cell lines as well as 73.3% (11/15) of pediatric acute myeloid leukemia (AML) samples. PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001). Kaplan-Meier survival analysis revealed that shorter survival time correlated with high tumor PLK1 expression (p = 0.002). The 50% inhibitory concentration (IC50) of RO3280 for acute leukemia cells was between 74 and 797 nM. The IC50 of RO3280 in primary acute lymphocytic leukemia (ALL) and AML cells was between 35.49 and 110.76 nM and 52.80 and 147.50 nM, respectively. RO3280 induced apoptosis and cell cycle disorder in leukemia cells. RO3280 treatment regulated several apoptosis-associated genes. The regulation of DCC, CDKN1A, BTK, and SOCS2 was verified by western blot. These results provide insights into the potential use of RO3280 for AML therapy; however, the underlying mechanisms remain to be determined.

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Expression of PLK1 is upregulated in AML cells and pediatric AML patients (A) Western blot analysis showing PLK1 protein expression in nine leukemia cell lines; (B) Western blot analysis showing PLK1 protein expression in 15 pediatric AML samples and 12 NBM samples; (C) Real-time PCR analysis of the PLK1 mRNA transcript levels in 105 pediatric AML samples and 30 NBM/ITP (normal bone marrow/idiopathic thrombocytopenic purpura) control samples; and (D) Kaplan-Meier survival analysis of 105 pediatric AML patients comparing high and low PLK1 expression (p = 0.002).
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ijms-16-01266-f001: Expression of PLK1 is upregulated in AML cells and pediatric AML patients (A) Western blot analysis showing PLK1 protein expression in nine leukemia cell lines; (B) Western blot analysis showing PLK1 protein expression in 15 pediatric AML samples and 12 NBM samples; (C) Real-time PCR analysis of the PLK1 mRNA transcript levels in 105 pediatric AML samples and 30 NBM/ITP (normal bone marrow/idiopathic thrombocytopenic purpura) control samples; and (D) Kaplan-Meier survival analysis of 105 pediatric AML patients comparing high and low PLK1 expression (p = 0.002).

Mentions: As reported previously, PLK1 is highly expressed in a broad set of cancer cell lines and overexpressed in a majority of cancer patient samples compared with normal progenitor cells. However, the expression of PLK1 in AML, and specifically pediatric AML, has not been clearly defined. We demonstrate that the expression of PLK1 is very high in AML cell lines, with the highest levels observed in CCRF, NB4, and K562 cells (Figure 1A). To examine the expression of PLK1 in pediatric AML samples, we obtained samples from 15 patients with pediatric AML and 12 control patients. High protein expression of PLK1 was observed in 73.3% (11/15) of the pediatric AML samples compared to 0% (0/12) of the normal bone marrow (NBM) control samples (Figure 1B). Real-time PCR was also used to examine the mRNA transcript levels of PLK1 in 105 pediatric AML samples and 30 NBM/ITP (idiopathic thrombocytopenic purpura) (control samples (Figure 1C)). PLK1 expression was significantly higher in the AML samples compared to the control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001). Bone marrow specimens were obtained from 105 pediatric patients with AML at the time of diagnosis, who presented at Children’s Hospital of Soochow University between 2000 and 2011. We suppose the high SD (standard deviation) values are related to the cDNA quality of samples. Examination of pediatric AML patient clinicopathology revealed that expression of PLK1 is related with FAB (French-American-Britain) and MRD (Minimal Residual Disease, Table 1). However, there were no significant differences in other clinical features such as sex, age, initial hemoglobin level, white blood cell counts, platelet counts, or chromosomal abnormalities between individuals with high and low PLK1 expression (Table 1). The prognostic significance of PLK1 expression was assessed in 105 Chinese pediatric AML patients with clinical follow-up records. Kaplan-Meier survival analysis revealed shorter survival times for patients with high PLK1 expression in tumors (p = 0.002, Table 2 and Figure 1C). Furthermore, multivariate analysis revealed that PLK1 expression is an independent prognostic factor in pediatric AML (p = 0.041, Table 3). In summary, our results demonstrate that PLK1 expression is heightened in patients with pediatric AML and in human myeloid leukemia cell lines. This indicates that PLK1 may be a suitable oncogene target for pediatric AML therapy.


Molecular targeting of the oncoprotein PLK1 in pediatric acute myeloid leukemia: RO3280, a novel PLK1 inhibitor, induces apoptosis in leukemia cells.

Wang NN, Li ZH, Zhao H, Tao YF, Xu LX, Lu J, Cao L, Du XJ, Sun LC, Zhao WL, Xiao PF, Fang F, Su GH, Li YH, Li G, Li YP, Xu YY, Zhou HT, Wu Y, Jin MF, Liu L, Ni J, Wang J, Hu SY, Zhu XM, Feng X, Pan J - Int J Mol Sci (2015)

Expression of PLK1 is upregulated in AML cells and pediatric AML patients (A) Western blot analysis showing PLK1 protein expression in nine leukemia cell lines; (B) Western blot analysis showing PLK1 protein expression in 15 pediatric AML samples and 12 NBM samples; (C) Real-time PCR analysis of the PLK1 mRNA transcript levels in 105 pediatric AML samples and 30 NBM/ITP (normal bone marrow/idiopathic thrombocytopenic purpura) control samples; and (D) Kaplan-Meier survival analysis of 105 pediatric AML patients comparing high and low PLK1 expression (p = 0.002).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4307303&req=5

ijms-16-01266-f001: Expression of PLK1 is upregulated in AML cells and pediatric AML patients (A) Western blot analysis showing PLK1 protein expression in nine leukemia cell lines; (B) Western blot analysis showing PLK1 protein expression in 15 pediatric AML samples and 12 NBM samples; (C) Real-time PCR analysis of the PLK1 mRNA transcript levels in 105 pediatric AML samples and 30 NBM/ITP (normal bone marrow/idiopathic thrombocytopenic purpura) control samples; and (D) Kaplan-Meier survival analysis of 105 pediatric AML patients comparing high and low PLK1 expression (p = 0.002).
Mentions: As reported previously, PLK1 is highly expressed in a broad set of cancer cell lines and overexpressed in a majority of cancer patient samples compared with normal progenitor cells. However, the expression of PLK1 in AML, and specifically pediatric AML, has not been clearly defined. We demonstrate that the expression of PLK1 is very high in AML cell lines, with the highest levels observed in CCRF, NB4, and K562 cells (Figure 1A). To examine the expression of PLK1 in pediatric AML samples, we obtained samples from 15 patients with pediatric AML and 12 control patients. High protein expression of PLK1 was observed in 73.3% (11/15) of the pediatric AML samples compared to 0% (0/12) of the normal bone marrow (NBM) control samples (Figure 1B). Real-time PCR was also used to examine the mRNA transcript levels of PLK1 in 105 pediatric AML samples and 30 NBM/ITP (idiopathic thrombocytopenic purpura) (control samples (Figure 1C)). PLK1 expression was significantly higher in the AML samples compared to the control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001). Bone marrow specimens were obtained from 105 pediatric patients with AML at the time of diagnosis, who presented at Children’s Hospital of Soochow University between 2000 and 2011. We suppose the high SD (standard deviation) values are related to the cDNA quality of samples. Examination of pediatric AML patient clinicopathology revealed that expression of PLK1 is related with FAB (French-American-Britain) and MRD (Minimal Residual Disease, Table 1). However, there were no significant differences in other clinical features such as sex, age, initial hemoglobin level, white blood cell counts, platelet counts, or chromosomal abnormalities between individuals with high and low PLK1 expression (Table 1). The prognostic significance of PLK1 expression was assessed in 105 Chinese pediatric AML patients with clinical follow-up records. Kaplan-Meier survival analysis revealed shorter survival times for patients with high PLK1 expression in tumors (p = 0.002, Table 2 and Figure 1C). Furthermore, multivariate analysis revealed that PLK1 expression is an independent prognostic factor in pediatric AML (p = 0.041, Table 3). In summary, our results demonstrate that PLK1 expression is heightened in patients with pediatric AML and in human myeloid leukemia cell lines. This indicates that PLK1 may be a suitable oncogene target for pediatric AML therapy.

Bottom Line: PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001).RO3280 treatment regulated several apoptosis-associated genes.These results provide insights into the potential use of RO3280 for AML therapy; however, the underlying mechanisms remain to be determined.

View Article: PubMed Central - PubMed

Affiliation: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou 215003, China. wangnn90s@163.com.

ABSTRACT
Polo-like kinase 1 (PLK1) is highly expressed in many cancers and therefore a biomarker of transformation and potential target for the development of cancer-specific small molecule drugs. RO3280 was recently identified as a novel PLK1 inhibitor; however its therapeutic effects in leukemia treatment are still unknown. We found that the PLK1 protein was highly expressed in leukemia cell lines as well as 73.3% (11/15) of pediatric acute myeloid leukemia (AML) samples. PLK1 mRNA expression was significantly higher in AML samples compared with control samples (82.95 ± 110.28 vs. 6.36 ± 6.35; p < 0.001). Kaplan-Meier survival analysis revealed that shorter survival time correlated with high tumor PLK1 expression (p = 0.002). The 50% inhibitory concentration (IC50) of RO3280 for acute leukemia cells was between 74 and 797 nM. The IC50 of RO3280 in primary acute lymphocytic leukemia (ALL) and AML cells was between 35.49 and 110.76 nM and 52.80 and 147.50 nM, respectively. RO3280 induced apoptosis and cell cycle disorder in leukemia cells. RO3280 treatment regulated several apoptosis-associated genes. The regulation of DCC, CDKN1A, BTK, and SOCS2 was verified by western blot. These results provide insights into the potential use of RO3280 for AML therapy; however, the underlying mechanisms remain to be determined.

Show MeSH
Related in: MedlinePlus