ABSTRACT
Expression of proteins related to cell surveillance has been described in tumors presenting resistance to photodynamic therapy (PDT). The aim of this study was to verify whether there was upregulation of proteins related to resistance in oral squamous cell carcinoma (OSCC) after PDT. OSCC was chemically induced in rats and treated after one cycle of PDT mediated by 5-aminolevulinic acid (5-ALA-PDT). Immunolabeling of p-NFκB, Bcl-2, survivin, iNOS, p-Akt, p-mTOR and cyclin D1 was performed after the treatment. There was increased expression of Bcl-2 (P = 0.008), iNOS (P = 0.020), p-Akt (P = 0.020) and p-mTOR (P = 0.010) by surviving neoplastic cells after PDT when compared to the control. In conclusion, after one cycle of 5-ALA-mediated PDT, Bcl-2, p-Akt, p-mTOR and iNOS were upregulated in neoplastic cells of OSCC, suggesting an activation of antiapoptosis and cell proliferation pathways. This fact must be considered in the establishment of PDT protocols for OSCC treatment, mainly those in which PDT will be combined with chemotherapy drugs targeted at the studied proteins.
Subject(s)
Aminolevulinic Acid/therapeutic use , Carcinoma, Squamous Cell/drug therapy , Mouth Neoplasms/drug therapy , Photochemotherapy , Photosensitizing Agents/therapeutic use , Carcinoma, Squamous Cell/metabolism , Humans , Mouth Neoplasms/metabolismABSTRACT
Photodynamic therapy (PDT) has been indicated for oral squamous cell carcinoma (OSCC) at early stages. Chemo and radio-resistance are frequently observed in OSCC, but it is unknown whether this tumor can develop resistance to PDT. It was investigated the process of acquiring resistance to multiple cycles of PDT by using OSCC cells. We also analyzed the expression of anti-apoptotic proteins and those related to Akt/mTOR pathway. Sub-lethal doses of PDT were applied, consisting of a constant concentration of 5-aminolevulinic acid (5-ALA) (1 mM, 4-h incubation) and increasing irradiation dose with LED (from 5.86 to 10.54 J/cm2 ). Cell viability, migration capacity, intracellular expression of protoporphyrin IX (PpIX), mitochondrial density, and pro-survival proteins were investigated in PDT-resistant cells. Six OSCC cell generations resistant to PDT were isolated. The resistant cells exhibited a survival phenotype characterized by a reduction in the expression of endogenous PpIX, increase in mitochondrial density, increase in migration capacity, and up-regulation of p-NFκB, p-survivin, iNOS, p-Akt Ser473 , cyclin D1, p-mTOR Ser2481 , and p-mTOR Ser2448 . OSCC cells are able to survive doses of 5-ALA-PDT by reducing PpIX synthesis and activating signaling pathways related to the inhibition of apoptosis and improvement of cell proliferation. Further studies are necessary to confirm whether this PDT-resistance phenotype can be clinically present, mainly in OSCC showing clinical recurrences after exposure to different PDT protocols.
Subject(s)
Aminolevulinic Acid/pharmacology , Photochemotherapy/methods , Apoptosis/drug effects , Blotting, Western , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Cell Survival/drug effects , Humans , Mouth Neoplasms/metabolism , Protoporphyrins/metabolism , Signal Transduction/drug effects , TOR Serine-Threonine Kinases/metabolismABSTRACT
O estudo das células-tronco cancerígenas (CTCs) durante o processo de malignização e no carcinoma epidermóide intra-bucal já instalado é essencial para um melhor entendimento de como essas células participam da formação e manutenção de uma neoplasia. Atualmente, a identificação de células com características de células tronco se dá principalmente através da expressão de marcadores celulares como o ALDH1 e o CD44. A proteína ALDH1 é responsável pela oxidação de aldeídos intracelulares e vem sendo utilizada para o isolamento de CTCs em inúmeros canceres incluindo casos de cabeça e pescoço. A proteína CD44 é uma glicoproteína envolvida na adesão e migração celular, também participa do processo de metástase e já foi associada às CTCs. Nesse trabalho, a expressão dessas proteínas foi analisada em 45 casos de displasias epiteliais e 13 casos de carcinomas epidermóide intra-bucais. As lesões displásicas foram classificadas em casos leves (19), moderados (18) e intensos (8) e foram também divididas em casos de baixo risco (22) e alto risco de transformação maligna (23). A expressão imunohistoquímica para a ALDH1 foi encontrada predominantemente na camada basal em 16 casos de displasias epiteliais e em 7 carcinomas epidermóides, com a marcação difusa pela epitélio neoplásico. A expressão imunohistoquímica de CD44 foi encontrada em 42 displasias epiteliais e em 12 carcinomas epidermóides, sendo que nas displasias, a expressão ocorreu predominantemente na camada basal do epitélio e no carcinoma epidermóide a expressão foi disseminada. Ambos marcadores exibiram aumento de expressão com a evolução do grau das displasias.
The study of cancer stem cells (CTCs) in the process of malignant transformation and intra-oral squamous cell carcinoma already installed is essential for a better understanding of how these cells participate in the formation and maintenance of a neoplasm. Currently, identification of cells with characteristics of stem cells is primarily through the expression of cell markers such as CD44 and ALDH1. The ALDH1 protein is responsible for the oxidation of intracellular aldehydes and has been used for the isolation of CTCs in numerous cancers including head and neck cases. The CD44 protein is a glycoprotein involved in cell adhesion and migration, also participates in the process of metastasis and has been associated with CTCs. In this work, the expression of these proteins was analyzed in 45 cases of epithelial dysplasia and 13 cases of intraoral squamous cell carcinomas. The dysplastic lesions were classified as mild (19), moderate (18) and intense (8) cases and were also divided into low-risk cases (22) and high risk of malignant transformation (23). The immunohistochemical expression for ALDH1 was found predominantly in the basal layer in 16 cases of epithelial dysplasia and squamous cell carcinoma in 7, with diffuse labeling by neoplastic epithelium. Immunohistochemical expression of CD44 was found in 42 epithelial dysplasias and 12 squamous cell carcinomas, and in dysplasias, the expression occurred predominantly in the basal layer of the epithelium and in squamous cell carcinoma expression was widespread. Both markers showed increased expression with the evolution of the degree of dysplasia.
