Tumor Biology

, Volume 36, Issue 12, pp 9567–9577 | Cite as

Plakophilin 1-deficient cells upregulate SPOCK1: implications for prostate cancer progression

  • Cheng Yang
  • Regina Fischer-Kešo
  • Tanja Schlechter
  • Philipp Ströbel
  • Alexander Marx
  • Ilse HofmannEmail author
Research Article


Plakophilin (PKP) 1 is frequently downregulated in prostate cancer and therefore may play a tumor-suppressive role. In the present study, we stably knocked down PKP1 in the non-neoplastic, prostatic BPH-1 cell line. In the PKP1-deficient cells, the expression of keratin 14 was lost, and the apoptosis rate was significantly reduced indicating that the cells acquired new biological capabilities. Moreover, we analyzed the gene expression profile of the PKP1-deficient BPH-1 cells. Among the genes that were significantly altered upon PKP1 knockdown, we noticed several extracellular matrix (ECM)-related genes and identified sparc/osteonectin, cwcv, and kazal-like domains proteoglycan 1 (SPOCK1/testican-1) as a gene of interest. SPOCK1 is a component of the ECM and belongs to a matricellular protein family named secreted protein, acidic, cysteine-rich (SPARC). The role of SPOCK1 in prostate cancer has not been clearly elucidated. We analyzed SPOCK1 mRNA expression levels in different cancer databases and characterized its expression in 136 prostatic adenocarcinomas by immunohistochemistry and western blot. SPOCK1 revealed a cytoplasmic localization in the glandular epithelium of the prostate and showed a significant upregulation of mRNA and protein in prostate tumor samples. Our findings support the hypothesis that PKP1 may have a tumor-suppressive function and suggest an important role of SPOCK1 in prostate tumor progression. Collectively, altered expression of PKP1 and SPOCK1 appears to be a frequent and critical event in prostate cancer.


Prostate cancer PKP1 SPOCK1 Extracellular matrix Testican-1 



This study was funded by grants from the German Cancer Aid (109248) and the “Deutsche Forschungsgemeinschaft” (HO 2455/3-1). Cheng Yang obtained a fellowship from the Chinese Scholarship Council (CSC). We thank the microarray unit of the DKFZ Genomics and Proteomics Core Facility for providing the Illumina Whole-Genome Expression Beadchips and related services.

Conflicts of interest


Supplementary material

13277_2015_3628_MOESM1_ESM.docx (22 kb)
ESM 1 (DOCX 21 kb)
13277_2015_3628_MOESM2_ESM.docx (24 kb)
ESM 2 (DOCX 23 kb)


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Copyright information

© International Society of Oncology and BioMarkers (ISOBM) 2015

Authors and Affiliations

  • Cheng Yang
    • 1
    • 2
    • 5
  • Regina Fischer-Kešo
    • 1
    • 2
  • Tanja Schlechter
    • 1
    • 2
  • Philipp Ströbel
    • 3
  • Alexander Marx
    • 4
  • Ilse Hofmann
    • 1
    • 2
    Email author
  1. 1.Division of Vascular Oncology and MetastasisGerman Cancer Research Center, DKFZ-ZMBH AllianceHeidelbergGermany
  2. 2.Department of Vascular Biology and Tumor Angiogenesis (CBTM), Medical Faculty MannheimHeidelberg UniversityMannheimGermany
  3. 3.Institute of PathologyUniversity Medical Center GöttingenGöttingenGermany
  4. 4.Institute of Pathology, University Medical Center MannheimHeidelberg UniversityMannheimGermany
  5. 5.Department of UrologyThe First Affiliated Hospital of Anhui Medical UniversityHefeiChina

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