الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Oral and pharyngeal cancer is the sixth most common cancer in the world. Oral cancer comprises an annual incidence rate of approximately 275,000 globally, where two-thirds of the cases have been mapped to occur in developing countries. Despite advances in the strategies for diagnosis and treatment, oral squamous cell carcinoma (OSCC) continues to have a poor 5-year survival rate .
OSCC, like other cancers, develops in an immune cell-rich environment, where the inflammatory cells in the tumor microenvironment work on establishing an anti-tumor response by secreting pro-inflammatory cytokines. However, cancer cells may induce various mechanisms that suppress the anti-tumor response, via a signaling network of suppressive cytokines. Since advances in the conventional treatments have not appreciably increased the survival rate of OSCC, attention has turned to immunotherapy including investigation of drugs that interfere with the Toll-like Receptor (TLR) signaling pathways.
Inactivated or attenuated pathogens are components of vaccines against infectious agents. Many are being tested as vectors for cancer vaccines. Bacillus Calmette– Guerin; BCG is the only vaccine currently available for tuberculosis that has been approved to treat superficial bladder cancer and bladder cancer in situ. Its action is based on the fact that BCG activate TLR 2 and TLR4 signaling and induce local inflammation in addition to tumor-specific immunity.
The objective of the current study was to evaluate the therapeutic effect of BCG vaccine as a TLR-4 agonist on human OSCC cell line (SCC-4) in terms of cell cytotoxicity, cytokines release and expression of proteins related to cancer cell apoptosis and proliferation. It also aimed at comparing the anti- cancer potentials of BCG versus the conventional chemotherapeutic drug cisplatin .
Summary
100
The current study initially assessed the expression of TLR-4 in OSCC paraffin blocks preserved in the tissue bank of Oral Pathology department, Faculty of Dentistry, Alexandria University. The intensity of the immunostaining was calculated in terms of mean area percent and mean optical density by image J software. TLR-4 was overexpressed in OSCC tissue specimens compared to the normal oral mucosa. The TLR-4 greatest immunoexpression was detected in the moderately differentiated grade, while the lowest value was noticed in the poorly differentiated type.
TLR-4 verification was done in SCC-4 cell line (in vitro) to ensure the presence of the receptor before applying the agonist. The in vitro study was conducted at the Center of Excellence for Research in Regenerative Medicine Applications, CERRMA, Alexandria Faculty of Medicine. Qualitative methods by confocal laser scanning microscopy, flowcytometry and ELISA techniques were applied for assessment of the determined parameters .
The cell viability in the SCC-4 cells was significantly decreased to (49.47%) at the BCG dose of 4.25 mg/ml when compared with the untreated cells; but showed approximately similar results to cells treated with the cisplatin ( 49.39 .)%
SCC-4 cells immunolabelled with anti- TLR4 and Alexa Fluor 555 antibodies were visualized by confocal laser scanning microscope. TLR-4 was localized mainly in the cytoplasm of the SCC-4 cells. The proliferation marker ki-67 and the apoptosis marker annexin V were assessed by flowcytometry for the SCC-4 cells incubated with BCG. Correlation between the results proved that BCG reduced cell proliferation and enhanced cell apoptosis in SCC-4 cells through enhancement of TLR-4 signaling mechanisms. In comparison to cisplatin, the anti-cancer effects of BCG on SCC-4 cell line was equivalent to the EC50 for Cisplatin.
The levels of IL-8 detected using ELISA in the supernatants of the cells treated with BCG were significantly higher than in case of the untreated cells. The upregulation of IL-8 confirmed that TLR-4 were functionally expressed in SCC-4 cells.
Summary
101
To sum up, BCG vaccine has an antitumor effect on human SCC4 cell line equivalent to the EC50 for Cisplatin. The anti-tumor potentials of BCG were mediated by enhancement of cytokine signaling immune mechanism. The action of BCG as a TLR-4 agonist could be attributed to its direct cytotoxic and apoptotic effects on SCC4 cell line.