Identification of Novel Cancer Biomarkers with Diagnostic and Therapeutic Potential for Cervical and Oesophageal Cancers Using a Targeted Proteomic Approach
Prof Virna Leaner
- Division of Medical Biochemistry & Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town
Title of the project
Identification of novel cancer biomarkers with diagnostic and therapeutic potential for cervical and oesophageal cancers using a targeted proteomic approach.
Cancer continues to be a highly prevalent disease in both developed and developing countries. The burden of cancer is on the rise with increasing life expectancy and approximately 20 million new cases are predicted per year globally from the year 2025 onward. In a middle-income country such as South Africa, cervical and oesophageal cancers, amongst others, are responsible for high cancer mortality rates. The need to detect cancer at an early stage before the disease spreads and becomes insensitive to treatment is thus of high importance. The advancement in modern laboratory technologies for the detection of DNA, RNA and protein in patient samples is enabling the examination of multiple proteins and genes in a single experiment. These technologies provide an opportunity to identify previously undescribed and novel cancer biomarkers that can be used for early diagnosis, prognosis and to predict therapeutic response. The use of serum or tissue biomarkers has been proposed to be one of the best approaches for use in early detection. Proteins with dysregulated expression and that are located on the cell surface or in secreted vesicles have the advantage of having both diagnostic and therapeutic potential. Traditionally, cancer biomarker discovery has focused on single biomarkers, which are advantageous in terms of cost and simplicity, but have been suggested to inaccurately capture the variability of disease through the population. Recently however, the analysis of multiple biomarkers, or a family of protein biomarkers, simultaneously, has received interest and is being shown to improve accuracy, sensitivity and specificity.
In previous work performed in our laboratory, aimed at identifying genes that associate with cancer as potential therapeutic and diagnostic targets;
- We identified genes with dysregulated expression in cervical cancer patient tissue compared to non-cancer tissue by microarray analysis and subsequent validation. Many of these genes had previously been associated with cancer progression and a number of novel genes, previously undescribed, were identified to have elevated expression in cervical cancer.
- Included in these were members of the nuclear transport protein family, the Karyopherin protein family. The Karyopherins are involved in mitotic spindle assembly and in nucleocytoplasmic transport pathways, which are critical to cancer cell survival.
- We showed that Karyopherins such as KpnB1, KpnA2 and Crm1 have elevated expression in cervical and oesophageal cancer cells and that cancer cells appear “addicted” to these proteins, as inhibiting their expression significantly inhibits cancer cell proliferation. Inhibition of KpnB1 and Crm1 by siRNA technologies and novel small molecule inhibitors results in cancer cell death in both in vitro and in vivo models, providing evidence for their potential as therapeutic targets.
- Furthermore, we showed through analyses based on the Pearson correlation coefficient, that the expression of the Karyoherin proteins significantly correlates with each other in cancer patient tissue, for example, where the one is increased, the others are similarly increased. This suggests that these proteins function in concert in mediating cancer biology, and that they are upregulated in cancer as a protein family.
- Finally, we have evidence that KpnB1, KpnA2 and Crm1 are secreted from cervical and oesophageal cancer cells and can be found in exosomes secreted by cells.
There is recent evidence in the literature showing that the Karyopherin family member, KpnA2, could serve as a potential cancer biomarker due to its elevated expression in cancer lung cancer tissue and its secretion by lung cancer cells. The work performed in our laboratory suggests that other Karyopherin proteins could likewise have potential as cancer biomarkers. Hence in this study, we propose to determine whether Karyopherin proteins could be useful biomarkers for the early detection of cervical and oesophageal cancers. This will be done using Mass Spectrometry to identify Karyopherin proteins secreted by cancer cells, followed by examination of Karyopherin proteins in patient blood by Elisa and Western blot analyses. We propose that if multiple family members could serve as cancer biomarkers (“a cancer biomarker family”), this would strengthen their potential for use in a cancer diagnostic test panel.