Dissecting the role of basement membrane components in a xenograft model of cutaneous squamous cell carcinoma (SCC) (O'Toole 1 Ext)Completed
|Project lead||Prof Edel O'Toole|
|Organisation||Queen Mary University of London, Centre for Cell Biology and Cutaneous Research, London, UK|
|Project budget||GBP 58,917.00|
|Start date / Duration||01. Apr 2015 / 12 months|
|Funder(s) / Co-Funder(s)||DEBRA UK, MSAP/EBEP Recommended|
|Research area||Skin cancer & fibrosis|
Short lay summary
Type VII collagen (ColVII) is a molecule which is responsible for adherence of the upper (epidermis) to the lower (dermis) part of the skin. Patients with recessive dystrophic epidermolysis bullosa (RDEB) have reduced or absent levels of ColVII due to an error in the DNA. As a result, patients have blistering and scarring of the skin and mucous membranes as well as a greatly increased risk of a type of skin cancer, squamous cell carcinoma (SCC). Patients develop SCC in areas of scarring as early as the third decade of life, and many die within 5 years of having their first SCC excised. In our study we analysed the effect of reduced/absent levels of ColVII on cutaneous SCC behaviour using RNA interference (RNAi), a technique where SCC cells are manipulated in vitro to lose ColVII expression. We showed for the first time that SCC cells without ColVII had an increased migration and invasion potential suggesting they have a higher tendency to metastasise, i.e. spread to areas outside the skin. Other aspects related to tumourigenesis were observed in ColVII-null cells, such as disorganised differentiation (a physiological process where cells in the lower part of the epidermis commit to move towards the surface through progressive changes and is usually deregulated in skin cancer), and abnormal levels of molecules known to “help” cancer cells to invade. A molecule known as TGF-beta seems to be implicated in tumourigenesis of cells with loss of ColVII. We performed in vivo experiments by grafting ColVII-null cells onto mice and were able to demonstrate that these cells invade more in vivo, expressing higher levels of TGF-beta and other molecules relevant for cell invasion, confirming our previous results. We have also shown in vitro and in vivo that loss of ColVII increases angiogenesis, a process where new blood vessels form from pre-existing ones. Angiogenesis has a crucial role in tumour development as it “helps” tumour cells to survive by supplying oxygen and nutrients. The observed changes were confirmed in skin sections both from RDEB scarred skin and RDEB SCC tumours. More recently, we were able to inject human recombinant ColVII (known to be identical to native human ColVII) into mice as well as zebrafish (another model used to study tumour invasion and angiogenesis in vivo) and revert formation of blood vessels further confirming the role of ColVII in angiogenesis and the importance of restoring type VII collagen expression for patients with RDEB. Understanding further the mechanism of the increased angiogenesis might allow the development of treatments to prevent cancer in RDEB patients. Inhibiting angiogenesis is also a possibility for patients living with SCC, but will require more in vivo animal model work.
We have demonstrated that loss of type VII collagen (shCol7) increases SCC invasion and angiogenesis in an in vivo model, and identified pro-angiogenic factors secreted by shCol7 SCC cells. Knock-down of the a3 chain of laminin 332 also markedly increases invasion, but not angiogenesis. Transcriptome/methylation data will be used to identify novel differential pathways which will be confirmed using immunostaining. Further investigation of angiogenesis includes immunostaining of RDEB SCC, dissection of the role of aVb6 integrin, TGFBR1 and the proangiogenic factors identified using a 3D model with SCC cells, a murine aortic ring model and a zebrafish in vivo model.