Abstract
Background The epidermis is a stratified epithelium whose differentiation program is triggered in part by calcium. Dysregulation of keratinocyte differentiation may lead to non-melanoma skin cancers, including cutaneous squamous cell carcinoma (cSCC). The compound 2-aminoethoxydiphenyl borate (2-APB) modulates calcium signaling by altering activity of calcium-permeable channels of the transient receptor potential (TRP) and ORAI families, and is therefore poised to govern signaling pathways that control the balance of keratinocyte proliferation and differentiation.
Objective We sought to determine whether 2-APB alters differentiation of normal human keratinocytes and progression of human cSCCs models in vitro.
Methods Primary human keratinocyte cultures were treated with 2-APB and levels of proliferation (EdU incorporation) and differentiation markers [quantitative PCR (qPCR)] were assessed. Human cSCC biopsies and cell lines were analyzed for TRP and ORAI gene expression via qPCR. cSCC cell lines were cultured in organtypic cultures and analyzed for growth and invasiveness after 2-APB or vehicle treatment.
Results Culturing human keratinocytes with 2-APB arrested cell proliferation, triggered differentiation-gene expression and altered epidermal stratification, indicating that 2-APB application is sufficient to promote differentiation. In human organotypic cSCC cultures, 2-APB attenuated tumor growth and invasiveness. Finally, expression of a panel of 2-APB-targeted ion channels (TRPV3, TRPV1, TRPC1, OraI1, OraI2 and OraI3) was dysregulated in high-risk cSCC biopsies.
Conclusions Collectively, these findings identify 2-APB as a potential therapeutic for high-risk cSCCs.
Footnotes
Funding: Funding was provided by NIAMS grant AR051219 (to EAL), NIEHS pilot award to P30 ES009089 to (EAL and DMO), ES020060 (to DMO). AMN was supported by a McNair Scholar Award. SAG was funded by NIH/NAMS P30AR044535-14 and YM was funded by 1T32HL120826. Histology was performed with support from the Columbia SDRC Research Cores (P30AR044535) and the Columbia HICCC Microscopy Resource (P30CA013696).
Conflict of Interest: EAL, AMN, YM and DMO have filed a patent application for the use of 2-APB and derivatives for the prevention and treatment of keratinocyte derived lesions.