Background Head and neck squamous cell carcinoma (HNSCC) has had little improvement in mortality rates in decades. A clearer understanding of the HNSCC tumor microenvironment will aid in finding more effective targeted therapies for this disease. Tumor associated fibroblasts (TAFs) are the largest stromal cellular components of the tumor microenvironment in HNSCC. Methods We isolated TAFs from clinical HNSCC cases and propagated in vitro. The effects of TAF secreted paracrine factors on in vitro HNSCC migration, invasion and proliferation was assessed. The effect of TAFs on HNSCC growth and metastases was determined in an orthotopic floor of mouth tumor model. Results TAF conditioned media increased HNSCC cell migration, invasion and proliferation. TAFs increased HNSCC tumor growth and metastases in vivo. Conclusions TAFs play a major role in increasing tumor growth and metastasis in HNSCC. Targeting the tumor stroma may be important to reduce the rate of HNSCC metastasis.

Despite aggressive therapies, head and neck squamous cell carcinoma (HNSCC) is associated with a less than 50% 5-year survival rate. Late-stage HNSCC frequently consists of up to 80% cancer-associated fibroblasts (CAF). We previously reported that CAF-secreted HGF facilitates HNSCC progression; however, very little is known about the role of CAFs in HNSCC metabolism. Here, we demonstrate that CAF-secreted HGF increases extracellular lactate levels in HNSCC via upregulation of glycolysis. CAF-secreted HGF induced basic FGF (bFGF) secretion from HNSCC. CAFs were more efficient than HNSCC in using lactate as a carbon source. HNSCC-secreted bFGF increased mitochondrial oxidative phosphorylation and HGF secretion from CAFs. Combined inhibition of c-Met and FGFR significantly inhibited CAF-induced HNSCC growth and ( < 0.001). Our cumulative findings underscore reciprocal signaling between CAF and HNSCC involving bFGF and HGF. This contributes to metabolic symbiosis and a targetable therapeutic axis involving c-Met and FGFR. HNSCC cancer cells and CAFs have a metabolic relationship where CAFs secrete HGF to induce a glycolytic switch in HNSCC cells and HNSCC cells secrete bFGF to promote lactate consumption by CAFs. .

Despite aggressive therapies, head and neck squamous cell carcinoma (HNSCC), which affects 50,000 new patients annually in the United States, is associated with less than 50% 5-year survival. HNSCC tumors display increased glycolysis, even in the presence of oxygen. Consequently, there is an increase in lactic acid (LA) production. However, the effect of lactic acid in the tumor microenvironment and the mechanisms whereby HNSCC tumors survive in highly acidic conditions remain unknown. HNSCC consist of up to 80% tumor-associated fibroblasts (TAFs). We previously reported that activation of receptor tyrosine kinase, c-Met, by TAF-secreted hepatocyte growth factor (HGF) contributes to HNSCC progression (1,2). The mechanism associated with tumor-stroma metabolic symbiosis is not well understood. On this basis, we hypothesized that TAF-secreted HGF regulates HNSCC glycolysis. We demonstrate that HNSCC-secreted basic fibroblast growth factor (bFGF) induces oxidative phosphorylation (OXPHOS) in TAFs. In addition, bFGF regulates secretion of HGF from TAFs. TAF-secreted HGF increases HNSCC glycolysis and induces bFGF secretion from HNSCC. Thus, HNSCC and TAFs engage in reciprocal signaling through paracrine effects of HGF and bFGF. Inhibition of c-Met with small molecule inhibitor PF-02341066 or specific knockdown with c-Met siRNA decreased TAF-facilitated HNSCC glycolysis, lactic acid production and bFGF expression. In addition, inhibition of FGFR with small molecule inhibitor AZD-4547 decreased OXPHOS and HGF expression in TAFs. Inhibition of FGFR also reduced HNSCC-stimulated phosphorylation of p42/44 mitogen activated protein kinase, proliferation and migration in TAFs. Further, we tested the efficacy of AZD-4547 in combination with c-Met inhibitor PF-02341066 in mitigating TAF-induced HNSCC growth in vitro and in vivo. Combined treatment with AZD-4547 and PF-02341066 significantly inhibited TAF-induced proliferation of HNSCC in vitro compared to the vehicle control treated cells (p&lt;0.001). Further, combined treatment significantly reduced growth of admixed HNSCC and TAF xenograft tumors (p&lt;0.001). Our cumulative findings underscore the therapeutic potential of combinatorial treatment with PF-02341066 and AZD-4547 in HNSCC. The therapeutic approach developed in this study may be a feasible in HNSCC. 1. Wheeler SE, Shi H, Lin F, Dasari S, Bednash J, Thorne S, et al. Enhancement of head and neck squamous cell carcinoma proliferation, invasion, and metastasis by tumor-associated fibroblasts in preclinical models. Head & neck 2014;36(3):385-92. 2. Knowles LM, Stabile LP, Egloff AM, Rothstein ME, Thomas SM, Gubish CT, et al. HGF and c-Met participate in paracrine tumorigenic pathways in head and neck squamous cell cancer. Clinical cancer research : an official journal of the American Association for Cancer Research 2009;15(11):3740-50. Citation Format: Dhruv Kumar, Vikalp Vishwakarma, Jacob New, Wade Gutierrez, Hemant Chavan, Partha Kasturi, Ossama Tawfik, Douglas Girod, Bennett Van Houten, George Leef, Radhika Joshi, Shary Shelton, Jeffrey Straub, Yelizaveta Shnayder, Kiran Kakarala, Terance Tsue, Fangchen Lin, Sumana Dasari, Sufi Thomas. Targeting tumor-stroma metabolic symbiosis for head and neck cancer therapy. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr B37.

<p>HNSCC Cells have Higher Glycolytic Capacity than CAFs and CAFs have Higher Maximal Respiration than HNSCC.</p>

<p>Combination of AZD-4547 and PF-02341066 indicates potentiated effect in admixed cultures but not in HNSCC only inoculated tumors.</p>