In vitro studies of osteosarcoma: a researcher's perspective of quantity and quality

Article / Letter to editorCWT

In vitro studies of osteosarcoma: a researcher's perspective of quantity and quality

Merit, Expertise and Measuremen

MicroRNAs at the human 14q32 locus have prognostic significance in osteosarcoma

Molecular tumour pathology - and tumour genetic

Pharmacological inhibition of Bcl-xL sensitizes osteosarcoma to doxorubicin

High-grade conventional osteosarcoma is the most common primary bone tumor. Prognosis for osteosarcoma patients is poor and resistance to chemotherapy is common. We performed an siRNA screen targeting members of the Bcl-2 family in human osteosarcoma cell lines to identify critical regulators of osteosarcoma cell survival. Silencing the anti-apoptotic family member Bcl-xL but also the pro-apoptotic member Bak using a SMARTpool of siRNAs as well as 4/4 individual siRNAs caused loss of viability. Loss of Bak impaired cell cycle progression and triggered autophagy. Instead, silencing Bcl-xL induced apoptotic cell death. Bcl-xL was expressed in clinical osteosarcoma samples but mRNA or protein levels did not significantly correlate with therapy response or survival. Nevertheless, pharmacological inhibition of a range of Bcl-2 family members showed that inhibitors targeting Bcl-xL synergistically enhanced the response to the chemotherapeutic agent, doxorubicin. Indeed, in osteosarcoma cells strongly expressing Bcl-xL, the Bcl-xL-selective BH3 mimetic, WEHI-539 potently enhanced apoptosis in the presence of low doses of doxorubicin. Our results identify Bcl-xL as a candidate drug target for sensitization to chemotherapy in patients with osteosarcoma

NTRK fusions are extremely rare in bone tumours

Aims Because of the efficacy of tropomyosin receptor kinase (Trk) inhibitor therapy in tumours with rearrangements of the neurotrophic tyrosine kinase receptor genes (NRTK genes), there has been a surge in demand for NTRK fusion screening. To date, most studies involving mesenchymal tumours have focused on soft tissue tumours, and data on bone tumours are sparse. Hence, we aimed to explore the frequency of NTRK fusions in a large series of primary bone tumours. Methods and results Immunohistochemical expression of pan-Trk was successfully assessed in 354 primary bone tumours by the use of tissue microarrays. In a selection of positive cases, additional molecular analysis for NTRK fusions was performed with anchored multiplex polymerase chain reaction-based targeted next-generation sequencing. Positivity was found in 19 cases (5%), which comprised Ewing sarcoma (n = 6, 33%), osteosarcoma (n = 11, 13%), and giant-cell tumour of bone (n = 2, 3%). In all except one case, cytoplasmic staining was observed. Weak staining was most often observed (n = 13), although five cases showed moderate staining and one case showed focal strong staining. Molecular analysis was successful in six cases, all of which were negative for NTRK fusions. Conclusion The likelihood of finding an NTRK fusion in bone tumours in clinical practice is extremely low. This may imply that, if more comprehensive large-scale molecular studies confirm this, routine predictive NTRK testing in bone tumour patients with advanced disease may be reconsidered.Molecular tumour pathology - and tumour geneticsMTG