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NORTH Dental Research starts its online e-conference today. NORTH stands for Network for Oral Research Training and Health. Below is the research project I did with two oral pathologists—Dr. Mark Darling and Dr. Tom Daley—at the University of Western Ontario (UWO), London, Ontario during summer 2005. Have a look. My research was awarded 2nd place in the Junior Category of 2005-06 CADR-IMHA Student Research Awards Competition.

Click the image to view presentation.

Human Kallikreins 5 and 8 Expressions in Salivary Gland Tumors

Background: Human tissue kallikreins (hKs) comprise 15 extracellular serine proteases secreted by various tissues. hKs are associated with malignancies such as prostate, breast, ovarian and testicular cancers, where hK expression levels are altered and represent prognostic factors. PCR analyses show that normal salivary glands express several hKs, but their physiological roles remain unknown.

Objective: This study investigated the expression levels of hK5 and hK8 in normal salivary glands, pleomorphic adenoma (PA), mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (ACC), polymorphous low grade adenocarcinoma (PLGA), acinic cell adenocarcinoma (ACI), and adenocarcinoma not otherwise specified (ANOS).

Method: Formalin-fixed paraffin-embedded human salivary gland tissues and tumors were evaluated by avidin:biotinylated-horseradish-peroxidase immunohistochemistry with appropriate positive and negative controls. Immunostaining signal was evaluated by two separate examiners and expressed as the sum of scores representing the proportion and staining intensity of cell cytoplasm (ranges 0-5 and 0-3, respectively).

Results: hK5 is absent in normal glands and most tumor cells, but present in keratin-producing epithelia of PA. hK8 is present in normal and all tumor tissues, with preferential expression in ductal cells. This trend is significant in normal glands (p<0.01, n=67) and PA (p<0.01, n=21), but not in ACC and PLGA. In MEC, intermediate cells have the highest hK8 expression, followed by squamous cells and then mucous cells (p≤0.04, n=22).

Conclusions: hK5 is associated with keratinized epithelia; however, its limited expression in normal and tumor tissues renders little value to diagnostic or prognostic application. hK8’s widespread expression, not specific to the tumors, cannot be used as a diagnostic marker to differentiate such tumors. However, its presence allows future investigation about whether its expression in each tumor will change in relation to cancer staging and grading—an important prognostic aspect for treatment planning and management of cancer patient after a diagnosis is established.

Key words: human kallikreins, hK, salivary gland tumors, immunohistochemistry
Source: http://www.northdentalresearch.ca/eConference/st7/index.pdf

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