Knockdown of spindle pole body component 25 homolog inhibits cell proliferation and cycle progression in prostate cancer

Abstract

Prostate cancer (PCa) is the most frequently diagnosed type of cancer in Chinese males. Cell-cycle aberration is a hallmark of cancer. Spindle pole body component 25 homolog (SPC25), a component of the Ndc80 complex, serves an important role in regulating mitotic chromosome segregation. However, the functional roles of SPC25 in PCa remain poorly understood. To the best of our knowledge, the present study was the first to demonstrate that SPC25 is significantly upregulated in PCa. In order to investigate the molecular roles of SPC25, a loss of function assay was performed, revealing that SPC25 knockdown inhibited cell proliferation, and induced a decrease in the number of cells in the S phase and an increase in the number of cells in the G2/M phase. Furthermore, SPC25 knockdown promoted the apoptosis of PCa cells. Additionally, bioinformatics analysis revealed multiple functional roles of SPC25 in regulating cell proliferation, apoptosis, invasion, transforming growth factor-β signaling and the SUMOylation pathway in PCa. The present study also evaluated the potential prognostic value of SPC25 using The Cancer Genome Atlas RNA-seq data and demonstrated that SPC25 was upregulated in late stage PCa. Kaplan-Meier analysis demonstrated that lower SPC25 expression was associated with an improved survival rate in patients with PCa. Taken together, these results suggested that SPC25 serves an oncogenic role in PCa and may act as a novel diagnostic and therapeutic target for PCa.

Keywords: cell cycle; prognosis; proliferation; prostate cancer; spindle pole body component 25 homolog.

Figure 1.

SPC25 expression was upregulated in PCa samples. TCGA data analysis demonstrated that (A) SPC25, (B) NDC80, (C) SPC24 and (D) NUF2 were differentially expressed in PCa samples compared with normal prostate tissues. (E) SPC25 was significantly upregulated in PCa samples compared with matched normal samples. (F) In the TCGA cohorts, >90% (35/38) of the paired PCa cases exhibited positive fold changes in SPC25 expression between the PCa samples and the adjacent normal tissues. P<0.05 was considered to indicate a statistically significant difference. ***P<0.001. SPC25, spindle pole body component 25 homolog; PCa, prostate cancer; TCGA, The Cancer Genome Atlas.

Figure 2.

SPC25 knockdown inhibits the proliferation of PC-3 cells. (A) Expression of SPC25 mRNA following transfection with the indicated shRNAs in PC-3 cells. (B) An MTT assay demonstrated that knockdown of SPC25 inhibited cell proliferation in PC-3 cells. (C) The Celigo^® system revealed that knockdown of SPC25 inhibited cell proliferation in PC-3 cells. (D) Cell number of shCtrl or shSPC25 group in each day was calculated using the Celigo^® system. P<0.05 was considered to indicate a statistically significant difference. **P<0.01; ***P<0.001. SPC25, spindle pole body component 25 homolog; sh, short hairpin; Ctrl, control; OD, optical density.

Figure 3.

SPC25 knockdown induced a decrease in the number of PCa cells in the S phase and an increase in the number of PCa cells in the G2/M phase. (A) The shSPC25-induced decrease in the number of PCa cells in the S phase and increase in the number of PCa cells in the G2/M phase. (B) Quantitative representation of the shSPC25-induced decrease in the number of PCa cells in the S phase and increase in the number of PCa cells in the G2/M phase. The cell cycle analysis results are presented as the mean ± standard deviation (n=3). P<0.05 was considered to indicate a statistically significant difference. **P<0.01 vs. shCtrl. SPC25, spindle pole body component 25 homolog; PCa, prostate cancer; sh, short hairpin.

Figure 4.

SPC25 knockdown promotes apoptosis of prostate cancer cells. (A) Flow cytometric analysis of the shSPC25-induced apoptosis of PC-3 cells. (B) Quantitative representation of the shSPC25-induced apoptosis of PC-3 cells. The cell apoptosis analysis results are presented as the mean ± standard deviation (n=3). P<0.05 was considered to indicated a statistically significant difference. ***P<0.001 vs. shCtrl. SPC25, spindle pole body component 25 homolog; sh, short hairpin; Ctrl, control.

Figure 5.

Bioinformatics analysis revealed multiple functional roles of SPC25 in PCa. (A) Heat map demonstrates differential genes expression following SPC25 knockdown. (B) IPA analysis demonstrated the potential pathways regulated by SPC25. (C) IPA analysis demonstrated the potential diseases and functions effected by SPC25 knockdown in PCa. SPC25, spindle pole body component 25 homolog; PCa, prostate cancer; IPA, ingenuity pathway analysis; KD, knockdown; NC, negative control.

Figure 6.

Upregulation of SPC25 predicts a poor prognosis in PCa. (A) SPC25 expression was upregulated in N1 PCa cases compared with N0 PCa cases. (B) SPC25 expression was upregulated in T3/T4 PCa cases compared with T2 PCa cases. (C) SPC25 expression was upregulated in Gleason 8 and Gleason 9 PCa cases compared with Gleason 6 or Gleason 7 PCa cases. (D) Compared with patients exhibiting a high SPC25 expression, the overall survival rates were higher in patients exhibiting a low SPC25 expression in the TCGA database. P<0.05 was considered to indicate a statistically significant difference. *P<0.05; ***P<0.001. SPC25, spindle pole body component 25 homolog; TPM, Transcripts Per Kilobase Million; PCa, prostate cancer; TCGA, The Cancer Genome Atlas.