BDNF signaling contributes to oral cancer pain in a preclinical orthotopic rodent model

Abstract

The majority of patients with oral cancer report intense pain that is only partially managed by current analgesics. Thus, there is a strong need to study mechanisms as well as develop novel analgesics for oral cancer pain. Current study employed an orthotopic tongue cancer model with molecular and non-reflexive behavioral assays to determine possible mechanisms of oral cancer pain. Human oral squamous cell carcinoma cells line, HSC2, was injected into the tongue of male athymic mice and tumor growth was observed by day 6. Immunohistological analyses revealed a well-differentiated tumor with a localized immune response and pronounced sensory and sympathetic innervation and vascularization. The tumor expressed TMPRSS2, a protein previously reported with oral squamous cell carcinoma. ATF3 expression in trigeminal ganglia was not altered by tumor growth. Molecular characterization of the model demonstrated altered expression of several pain-related genes, out of which up-regulation of BDNF was most striking. Moreover, BDNF protein expression in trigeminal ganglia neurons was increased and inhibition of BDNF signaling with a tyrosine kinase B antagonist, ANA-12, reversed pain-like behaviors induced by the oral tumor. Oral squamous cell carcinoma tumor growth was also associated with a reduction in feeding, mechanical hypersensitivity in the face, as well as spontaneous pain behaviors as measured by the conditioned place preference test, all of which were reversed by analgesics. Interestingly, injection of HSC2 into the hindpaw did not reproduce this spectrum of pain behaviors; nor did injection of a colonic cancer cell line into the tongue. Taken together, this orthotopic oral cancer pain model reproduces the spectrum of pain reported by oral cancer patients, including higher order cognitive changes, and demonstrates that BDNF signaling constitutes a novel mechanism by which oral squamous cell carcinoma induces pain. Identification of the key role of tyrosine kinase B signaling in oral cancer pain may serve as a novel target for drug development.

Characterization of sensory neuronal subtypes innervating mouse tongue

“…Sections were placed onto Superfrost Plus slides (Fisher Scientific, Waltham, MA, USA), dried and stored at −20°C until stained. Immunostaining was performed as described previously [ 13 , 32 , 33 ]. Briefly, tissue sections were permeabilized and blocked for non-specific protein binding with blocking solution consisting of 4% normal goat serum (Sigma, St. Louis, MO), 2% bovine gamma- globulin (Sigma-Aldrich, St. Louis, MO) and 0.3% Triton X-100 (Fisher Scientific) in PBS for 90min prior to incubation with primary antibodies in blocking solution for 16h.…”

Mouse Tumor-Bearing Models as Preclinical Study Platforms for Oral Squamous Cell Carcinoma

“…Because different immunodeficient mice are used, the xenograft tissue lacks the structure of a typical immune system, although the immune cells are not absent. HE staining of HSC2-bearing tongues, dissected from athymic nude mice injected with HSC2 cells, revealed an immune reaction that included neutrophils, lymphocytes, and macrophages (107). CDX models can be considered PDX models with too many generations to be traceable.…”

Antitumor Activities and Cellular Changes Induced by TrkB Inhibition in Medulloblastoma

“…In vivo studies were performed in accordance with procedures approved by the Brazilian (Cazorla et al, 2011;Chodroff et al 2016). After treatment, all the mice were euthanized, and the tumors were excised, measured and weighed.…”