Serglycin (SG) is a proteoglycan carrying negatively charged unbranched sugar-chains (glycosaminoglycans, GAGs). SG is normally expressed by many immune cells, for example mast cells and macrophages. SG has no intrinsic “activity”, but with the negatively charged GAGs it contributes to the intracellular storage (granular retention) of positively charged proteins, or extracellularly as a carrier molecule of positively charged mediators. Many cancer forms also express SG, where a clear correlation between a high expression level and a poor prognosis has been observed.
Using the serglycin-defective mouse strain in an orthotopic udder/breast cancer model we recently discovered that SG is essential for cancer cell metastasis, i.e. for extravasation of tumor cells to the lung. This striking finding together with the correlative prognostic value in humans led us to investigate the expression of SG in different forms of canine cancer, for example splenic hemangiosarcoma, udder cancer, and mastocytoma. Today we have confirmed that the levels of canine SG follows the grading in the investigated tumor forms.
The project now continues and we plan to investigate how and what makes SG essential for the metastatic process of different human and canine cancer forms.
Possible project questions remaining are:
a) The pathology section at BVF provides an archive of different tumor material as well as normal tissue. In the project, initially histological evaluations of the selected tumor material is performed, and then RNA, DNA and protein is prepared from the retrospective material, and used for different molecular investigations (for example qPCR, point mutations as well as proteomics).
b) Blood and serum samples have been/are collected from canine cancer patients at UDS. In the project, these samples are analyzed with qPCR for the expression levels of SG and with “finger-print” proteomics (a method currently under development in the group) for analysis of the protein/peptide levels of SG in serum.
A preliminary proteomics analysis of cells from the SG-knockout mouse strain identified several potentially SG-dependent mediators. In the project, CRIPSR/Cas9 methods are used to develop different SG-deficient canine and human cancer cell lines, for comparison against untreated SG-competent cancer cell lines. Cultivation of cancer cell lines, transfections with the CRIPSR/Cas9-RNP-complex, and downstream analyses such as microscopy, different PCR-methods and proteomics are methods performed in the project work. The long term goal is to identify which proteins/mediators in cancer metastases that is SG-dependent.
Open project start, exam project for veterinarians, and for candidate and master students
Link to the group Magnus Åbrink | Medarbetarwebben (slu.se)