Despite tremendous efforts over the last decades, current screening methods for cervical cancer still have limitations in sensitivity and/or specificity. Moreover, vaccines are not effective against all HPV types and efficiency is uncertain in case of previous infection. In the search for more specific and sensitive biomarkers, and additional challenge represents the application of these biomarkers in low- and middle income countries where the incidence of cervical cancer is highest. The Cervico Vaginal Fluid (CVF) is composed of secretions originating from organs that are part of the female genital tract, including vagina, cervix, endometrium and ovaries; hence the proteome of this fluid contains a wealth of information concerning the physiological status of all of these organs. Since many studies have proven self-sampling as a good and acceptable sample collection method for subsequent DNA genotyping, cytology or immunohistochemistry, CVF may very well be suited for the development of a selftest for triage of suspected cases or screening in low- and middle income countries.
A differential proteomics study on CVF was performed using six CVF samples from healthy and six samples from precancerous women. Extracted proteins were run over a 2D-LC-MS/MS platform and quantified by spectral counting. Lists of identified CVF proteins were analyzed by Ingenuity pathway Analysis (IPA) to find out whether cervix cancer pathways were reflected in the CVF. A series of candidate biomarker proteins was further validated by ELISA or mass spectrometry (MRM).
We identified alpha-actinin-4 (ACTN4) as a protein biomarker that could discriminate between the healthy and (pre)cancerous states with a sensitivity and specificity of resp. 84 and 86%. Based on the list of proteins that were differentially abundant in both types of CVF, a set of cervical cancer protein biomarkers interconnected within several cancer-related pathways was identified by Ingenuity Pathway Analysis (IPA). We quantified these biomarkers by ELISA or mass spectrometry (MRM) in CVF samples from healthy or precancerous woman in order to further increase the discriminative power in combination with ACTN4.
The cervical vaginal fluid may contain several biomarkers which, when used in an appropriate combination, could be used for development of an accurate cervical cancer screening test. Since collection of CVF is non-invasive, these biomarkers allow for the development of a self-diagnosis test to be used for screening, prediction or follow-up of cervix cancer.
[Van Raemdonck et al. Identification of protein biomarkers for cervical cancer using human cervicovaginal fluid. PLoS One. 9:e106488 (2014).]