Notch 1 Receptor, Delta 1 Ligand and HES 1 Transcription Factor are Expressed in the Lining Epithelium of Periapical Cysts (Preliminary Study)

Abstract

Periapical cyst is a chronic inflammatory disorder of periradicular tissues. The precise pathological mechanisms involved in periapical cyst enlargement remain unclear. Notch signaling is an evolutionarily conserved pathway with a regulatory role in cell fate decisions during development and in carcinogenesis. To date, there are no published data available on the expression of Notch signaling components in periapical cysts or any other jaw cyst. In this immunohistochemical study we have examined the expression of the receptor Notch 1, the ligand Delta 1 and the transcription factor HES 1 in the epithelium of well defined periapical cysts. Immunostaining reaction of Notch 1, Delta 1 and HES 1 was observed in the cytoplasm and/or the cytoplasmic membrane and occasionally in the nucleus in the majority of epithelial cells of all periapical cysts. The present observations indicate that Notch pathway is active in the epithelium of periapical cysts. It can be speculated that activation of epithelial cells of periapical cysts is associated with activation of Notch pathway and imply involvement of this pathway in periapical cyst growth and expansion.

Notch-1/2 receptors and Jagged-1 ligand, but not HERP-1 transcription factor, are immunohistochemically expressed in the epithelial lining of periapical cysts

“…Notch-1, Notch-2, and Jagged-1 were expressed in basal and parabasal layers in most of the periapical cysts examined in the present study. As those cells behave as unipotent stem cells having the ability of cell division on inflammatory stimulation ( 12 ), it is suggested that Notch activation may be involved in cell proliferation.…”

“…Notch-1, Notch-2, and Jagged-1 were expressed in basal and parabasal layers in most of the periapical cysts examined in the present study. As those cells behave as unipotent stem cells having the ability of cell division on inflammatory stimulation (12), it is suggested that Notch activation may be involved in cell proliferation. On the contrary, in normal epidermis Notch participates in differentiation, i.e., overexpression of Notch-1 in the basal cells inhibits proliferation and promotes premature differentiation; however, overexpression in squamous cells induces hyperproliferation of basal cells and epithelial hyperplasia (22).…”

“…Notch-2 is expressed in the Hertwig's epithelial root sheath, whose remnants, ERM, are thought to give rise to the lining epithelium of periapical cysts. Expression of Notch in ERM indicates that this pathway may be, also, involved in the pathogenesis of periapical cysts (12). Notch receptors have been found in the lining epithelium (3) and inflammatory cells (13) of periapical cysts.…”

miR‐139‐5p upregulation alleviated spontaneous recurrent epileptiform discharge‐induced oxidative stress and apoptosis in rat hippocampal neurons via regulating the Notch pathway

“…In addition, the Notch signaling pathway also caused neuroinflammation and neuron damages related to inflammation in epilepsy (Wu et al, 2018). As one of the structurally similar Notch ligands, Notch‐1 has been found to interact with miRs in cancer cells (Meliou et al, 2010, Prokopi et al, 2014). Prior study revealed that in epilepsy, suppressing miR‐34a in neurons led to an increase in Notch signaling levels, accompanied by inhibited epileptiform discharges and neuron apoptosis (Wang et al, 2019).…”