Expression profiles of mTOR pathway proteins in porocarcinoma: A provisional immunohistochemical study

Abstract

Porocarcinoma is a rare skin appendage carcinoma, with a poor prognosis. At present, the recommended treatment of localized porocarcinoma is wide surgical resection. Although anthracyclin-based chemotherapy or combination of 5-fluorouracil (5-FU), taxanes and cisplatin are considered to be the first-line treatment for metastatic or locally-advanced porocarcinoma, this type of tumor is recognized as relatively chemoresistant, and no standard systemic treatment has been established yet. Mammalian target of rapamycin (mTOR) is an important protein involved in carcinogenesis. mTOR phosphorylates the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), and then phosphorylated 4E-BP1 (p4E-BP1) triggers cell cycle progression, cell proliferation and angiogenesis. Therefore, mTOR is believed to be one of the most promising therapeutic targets in various types of carcinomas. However, the expression profiles of mTOR pathway proteins in porocarcinoma have yet to be elucidated. Therefore, we analyzed the expression of mTOR, 4E-BP1 and p4E-BP1 in five cases of porocarcinoma (four invasive and one case) using immunohistochemical methods. mTOR expression was observed in the invasive porocarcinoma cases, but not in the case. 4E-BP1 was expressed in all five cases. p4E-BP1 expression was observed in 3/4 invasive porocarcinoma cases, but not in the case. This preliminary study clearly demonstrated the overexpression of mTOR and its downstream proteins in most of the included invasive porocarcinoma cases. Therefore, mTOR inhibitors could be considered as potential therapeutic modalities for the treatment of metastatic or locally-advanced porocarcinoma.

Authors: Janakiram Trichy Narayanan, Sagar Shalini, Sharma Shilpee Bhatia, Subramaniam Vijayalakshmi Klinicka onkologie Journal. 2016; 29(4): 291-294. DOI: 10.14735/amko2016291. Background: Lacrimal sac tumors are very rare and are often missed because patients present with features consistent with chronic dacryocystitis. Squamous cell carcinoma is the commonest lacrimal sac malignancy. Although primary mucoepidermoid carcinomas of the lacrimal sac are rare, they are locally aggressive. Furthermore, their

“…mTOR is a serine/ threo nine kinase that regulates cell growth and metabolism. Activation of mTOR and its regulatory proteins have been repor ted in various tumors that makes mTOR inhibitor to be a promising ther apeutic agent in the treatment [19][20][21][22][23]. The possibility of receptor marker expres sion in individual tumor may open up the options of target oriented systemic treatment along with radiother apy to prevent recurrence.…”

Porocarcinoma ecrino metastásico

“…En un estudio de 4 casos de porocarcinoma ecrino se evidenció 3 casos con sobreexpresión de la vía mTOR, por tanto, los inhibidores de esta vía podrían considerarse modalidades terapéuticas potenciales para el tratamiento del porocarcinoma invasivo metastásico (18) . Se debe, se debe tener en cuenta este diagnóstico para la identificación y resección quirúrgica tem-prana, la cual disminuye la mortalidad por esta entidad poco frecuente.…”