Molecular characterization of cachexia in a novel head and neck cancer mouse model

Despite accounting for only ~4% of all cancers in the US, experimental and clinical observations suggest that ~40% of patients with head and neck cancer (HNC) present with 'cachexia', a severe comorbidity that associates with skeletal muscle defects and is responsible for decreased muscle function, worsened response to treatment, and poorer outcomes. Despite its clinical relevance, the mechanism(s) responsible for the onset of cachexia in HNC patients are not completely understood, thus leading to limited progress in diagnosis and representing a barrier to the development of treatments. Moreover, impeding the identification of viable therapies to combat HNC cachexia is also the limited availability of small animal models. Here, we characterized molecular and functional features of cachexia in a novel, preclinical model for the study of HNC, namely the mouse bearing the B0092 oral squamous cell carcinoma, transplantable in recipient C57BL/6 mice To investigate the systemic effects of HNC tumors, 10-week-old C57BL/6 male mice were implanted with B0092 cells (5x105 cells, s.c.) and monitored for up to 36 days. Growth of B0092 tumors was accompanied by skeletal muscle atrophy, loss of Extensor Digitorum Longus (EDL) muscle strength, reduced bone mineral density (BMD), measured by DEXA, and decreased trabecular bone, assessed using microCT. To identify the gene signature associated with muscle wasting caused by B0092 tumors, we performed Next Gen RNA-Sequencing of quadriceps muscle. The pathway analysis conducted using the Ingenuity Pathway Analysis (IPA) and integrated Differential Expression and Pathway (iDEP) bioinformatic tools, revealed dysfunction of mitochondria, as well as upregulation of proteasome- and translation-related pathways. In conclusion, our data suggests that B0092-bearing mice can be a useful tool to uncover novel molecular pathways and potential therapeutic targets for the treatment of HNC cachexia. Overall design: To study the ability of B0092 head and neck squamous cell carcinoma (HNSCC) cell line to induce cahcexia, first, 8-week-old C57BL/6J mice were separated into control (n=4) and tumor bearing (n=4) groups. B0092 cells were injected s.c. near the nape of the neck with 200uL of 5x10^5 cells per mouse, while controls were injected with equal amounts of PBS vehcle. Mice were monitered for weight and muscle loss. When the mice reached ~10% weight loss from initial values (day 36), they were sacrificed and skeletal muscles and organs were collected and snap frozen in liquid nitrogen. Bulk RNASeq was performed on RNA isolated from the quadriceps muscle of both groups.