gms | German Medical Science

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2017)

24.10. - 27.10.2017, Berlin

Sox9 as a proto-oncogene in a chondrosarcoma cell line

Meeting Abstract

  • presenting/speaker Sabine Stöckl - Orthopädische Klinik der Universität Regensburg, Experimentelle Orthopädie, ZMB im BioPark 1, Regensburg, Germany
  • Ferdinand Wagner - Kinderchirurgische Klinik und Poliklinik, Dr. von Haunersches Kinderspital, LMU, München, Germany
  • Claudia Göttl - Orthopädische Klinik der Universität Regensburg, Experimentelle Orthopädie, ZMB im BioPark 1, Regensburg, Germany
  • Joachim Grifka - Klinik und Poliklinik für Orthopädie, Lehrstuhl für Orthopädie der Universität Regensburg, Asklepios Klinikum Bad Abbach, Bad Abbach, Germany
  • Susanne Grässel - Orthopädische Klinik der Universität Regensburg, Experimentelle Orthopädie, ZMB im BioPark 1, Regensburg, Germany

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2017). Berlin, 24.-27.10.2017. Düsseldorf: German Medical Science GMS Publishing House; 2017. DocGR20-416

doi: 10.3205/17dkou546, urn:nbn:de:0183-17dkou5462

Veröffentlicht: 23. Oktober 2017

© 2017 Stöckl et al.
Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). Lizenz-Angaben siehe



Objectives: Sox9 is the master transcription factor for chondrogenesis. From the mesenchymal condensation of chondroprogenitors to the hypertrophic maturation of chondrocytes, Sox9 has an essential role in inducing the expression of different chondrogenic genes and is also involved in the regulation of proliferation, apoptosis and cell signaling cascades. But moreover, accumulating evidence from recent studies point to a critical role of Sox9 as a proto-oncogene in plenty of different tumor types. Especially in chondrosarcoma and osteosarcoma, Sox9 is presumed to influence the development and progression of the tumors, as well as the overall survival rate of patients, however the molecular mechanism behind these effects are still unclear.

Methods: We have introduced a transient Sox9 knockdown using specific Sox9 siRNA and a stable Sox9 knockout using CRISPR/Cas9 technology into a human chondrosarcoma cell line (HTB 94). Functional assays to investigate apoptosis (Caspase 3/7), adhesion (crystal violet staining), migration (boydn chamber), invasion (boydn chamber containing matrigel) and the ability to form colonies (colony forming assay) were performed with Sox9-knockdown cells. The capacity of these cells to differentiate along the chondrogenic lineage was analyzed via quantification of marker genes (qPCR). In addition, doubling time, viability, average cell diameter and tendency to form aggregates of different Sox9-knockout clones were verified using a cell counter.

Results and Conclusion: A reproducible knockdown of Sox9 on mRNA and protein level (80% - 90%) was achieved using siRNA in HTB94 cells. In Sox9 knockdown-cells a significant increase in apoptotic activity and an enhanced adhesion capacity was observed whereas the migration ability was unaltered and invasion and colony forming capacity was decreased. 100% knockdown of Sox9 in HTB94 cells revealed an increase in doubling time (38h) compared to control cells (28h), a slightly decreased average cell diameter (10%) and a strongly decreased aggregate rate (50% - 60%), whereas viability was unaltered. Differentiation studies with Sox9 knockdown cells showed a decreased expression of COL1A1, COL2A1 and Integrin alpha 11 (ITG11) during the first two weeks in chondrogenic differentiation medium, while in a later phase, increased expression of COL10A1 points to an acceleration of the transition into a hypertrophic status.

Based on these studies, we conclude a critical effect of Sox9 on apoptosis, cell-cell and cell-surface adhesion, invasion and colony forming ability as well as on cell doubling time in a human chondrosarcoma cell line. These data point to a role of Sox9 as a pro-survival factor and a possible proto-oncogene for sarcoma cells, which could strongly influence the tumorigenic potential and is thereby conceivable as a prognostic factor. Probably, Sox9 expression alters the balance between self-renewal and differentiation capacity, what could be the central point of action for Sox9 in tumor cells.