Establishment of Novel Sinonasal Nut Carcinoma Cell Lines

Objective: NUT carcinoma is a rare and aggressive tumor of the upper aerodigestive tract with a median survival time of approximately 6 to 7 months. According to the latest WHO classification of Head and Neck Tumors, it is “a poorly differentiated carcinoma defined by the presence of nuclear protein in testis (NUT) gene (NUTM1) arrangement.” In two-thirds of cases, NUTM1 is fused to the bromodomain-containing protein 4 (BRD4) gene, and this fusion disrupts cellular differentiation and promotes oncogenesis. There is no standard treatment for NUT carcinoma; therefore, there is a need to develop new experimental models and improve treatment strategies. However, due to the rarity of this disease, only few NUT carcinoma cell lines are available, especially from the sinonasal tract. Here, we report the establishment and characterization of two novel sinonasal NUT carcinoma cell lines.

Materials and Methods: Cell lines were established from a 28-year-old male patient with a T4b sinonasal NUT carcinoma who was treated with multimodal therapy including surgical resection at our cancer center. The resected specimen had multiple molecular abnormalities including the BRD4-NUTM1 fusion. The specimen was cultured in Dulbecco's Modified Eagle Medium with 10% fetal bovine serum and was split once tumor cells became confluent. Genomic DNA was purified to perform DNA fingerprinting. NUT protein expression in the cell lines was detected by immunohistochemistry staining. Cell growth inhibition with the bromodomain inhibitor OTX-015 was assessed by the Cell Titer-Glo Assay.

Results: Two populations successfully grew for over 35 passages and were named MDA-NUT87 and MDA-NUT88. The morphology of the cell lines was heterogeneous; a mixture of squamous cell carcinoma–like cells and piled-up, undifferentiated round small cells. DNA genotyping revealed that the NUT cell lines were unique and no evidence of culture contamination. Immunohistochemistry showed that these cell lines maintained strong nuclear NUT1 protein expression. The bromodomain inhibitor OTX-015 showed effective growth suppression in the NUT carcinoma cell lines (IC50 ~50 nM).

Conclusion: We successfully established two novel sinonasal NUT carcinoma cell lines that maintain the same molecular features of the original tumor and are sensitive to bromodomain inhibition. These cell lines should serve as useful tools for future study of sinonasal NUT carcinoma and development of new therapies for this lethal disease.

Publication History

Article published online:
15 February 2022