title: IB4(+) and TRPV1(+) sensory neurons mediate pain but not proliferation in a mouse model of squamous cell carcinoma.
abstract: BACKGROUND
  Cancer pain severely limits function and significantly reduces quality of life. Subtypes of sensory neurons involved in cancer pain and proliferation are not clear.
  
  
  METHODS
  We produced a cancer model by inoculating human oral squamous cell carcinoma (SCC) cells into the hind paw of athymic mice. We quantified mechanical and thermal nociception using the paw withdrawal assays. Neurotoxins isolectin B4-saporin (IB4-SAP), or capsaicin was injected intrathecally to selectively ablate IB4(+) neurons or TRPV1(+) neurons, respectively. JNJ-17203212, a TRPV1 antagonist, was also injected intrathecally. TRPV1 protein expression in the spinal cord was quantified with western blot. Paw volume was measured by a plethysmometer and was used as an index for tumor size. Ki-67 immunostaining in mouse paw sections was performed to evaluate cancer proliferation in situ.
  
  
  RESULTS
  We showed that mice with SCC exhibited both mechanical and thermal hypersensitivity. Selective ablation of IB4(+) neurons by IB4-SAP decreased mechanical allodynia in mice with SCC. Selective ablation of TRPV1(+) neurons by intrathecal capsaicin injection, or TRPV1 antagonism by JNJ-17203212 in the IB4-SAP treated mice completely reversed SCC-induced thermal hyperalgesia, without affecting mechanical allodynia. Furthermore, TRPV1 protein expression was increased in the spinal cord of SCC mice compared to normal mice. Neither removal of IB4(+) or TRPV1(+) neurons affected SCC proliferation.
  
  
  CONCLUSIONS
  We show in a mouse model that IB4(+) neurons play an important role in cancer-induced mechanical allodynia, while TRPV1 mediates cancer-induced thermal hyperalgesia. Characterization of the sensory fiber subtypes responsible for cancer pain could lead to the development of targeted therapeutics.
authors: Yi
authors: Y
authors: Ye
authors: Sam S
authors: SS
authors: Bae
authors: Chi T
authors: CT
authors: Viet
authors: Scott
authors: S
authors: Troob
authors: Daniel
authors: D
authors: Bernabé
authors: Bluestone Center for Clinical Research, New York University, New York, USA. bls322@nyu.edu.
authors: Brian L
authors: BL
authors: Schmidt
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D037102:Lectins / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D009062:Mouth Neoplasms / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D010146:Pain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D010147:Pain Measurement; D011984:Sensory Receptor Cells / Q000378:metabolism*; D050916:TRPV Cation Channels / Q000378:metabolism*
chemical_list: D037102:Lectins; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse