AimWe have previously demonstrated the presence of two cancer stem cell (CSC) subpopulations within metastatic head and neck cutaneous squamous cell carcinoma (mHNcSCC) expressing components of the renin-angiotensin system (RAS), which promotes tumorigenesis. Cathepsins B, D and G are enzymes that constitute bypass loops for the RAS. This study investigated the expression and localization of cathepsins B, D, and G in relation to CSC subpopulations within mHNcSCC.MethodsImmunohistochemical staining was performed on mHNcSCC tissue samples from 20 patients to determine the expression and localization of cathepsins B, D, and G. Immunofluorescence staining was performed on two of these mHNcSCC tissue samples by co-staining of cathepsins B and D with OCT4 and SOX2, and cathepsin G with mast cell markers tryptase and chymase. Western blotting and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were performed on five mHNcSCC samples and four mHNcSCC-derived primary cell lines, to determine protein and transcript expression of these three cathepsins, respectively. Enzyme activity assays were performed on mHNcSCC tissue samples to determine whether these cathepsins were active.ResultsImmunohistochemical staining demonstrated the presence of cathepsins B, D and G in in all 20 mHNcSCC tissue samples. Immunofluorescence staining showed that cathepsins B and D were localized to the CSCs both within the tumor nests and peri-tumoral stroma (PTS) and cathepsin G was localized to the phenotypic mast cells within the PTS. Western blotting demonstrated protein expression of cathepsin B and D, and RT-qPCR demonstrated transcript expression of all three cathepsins. Enzyme activity assays showed that cathepsin B and D to be active.ConclusionThe presence of cathepsins B and D on the CSCs and cathepsin G on the phenotypic mast cells suggest the presence of bypass loops for the RAS which may be a potential novel therapeutic target for mHNcSCC.
Immunology education remains an essential component for undergraduate Health Sciences education across the health professions. The clinical relevance of Immunology teaching can be emphasised by utilisation and appropriate reference to pertinent health conditions affecting populations locally and across the global setting. Health issues of significance to Māori and Pacific populations groups in Aotearoa/New Zealand and in the Pacific Region include Cancer and Acute Rheumatic Fever (ARF) and Rheumatic Heart Disease (RHD). ARF is the body’s autoimmune response to untreated Group A Streptococcal (GAS) infection of the throat or skin. If left untreated, repeated or severe ARF episodes can lead to permanent cardiac damage known as RHD. RHD is a significant cause of morbidity and mortality worldwide. The growing global burden of cancer remains of concern, while Pacific Peoples and Māori are disproportionately affected by specific cancers. The utilisation of two areas with strong Immunological relevance for teaching examples in undergraduate Health Sciences education were shown to support improved understanding, class participation, topical interest, and research focus for Medical students engaged within Health Sciences education platforms in Aotearoa/New Zealand. This highlights the value of supporting Immunology education efforts by incorporating appropriate reference to pertinent health conditions relevant to populations groups locally and across the global setting.
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