PROJECT SUMMARY
Postoperative surveillance (PS) by medical imaging is critical for the management of clear cell renal cell
carcinoma (ccRCC) patients. However, it is expensive and leads to increased risk for secondary malignancy
due to accumulative exposure to radiation. Similar challenges exists in monitoring treatment response for renal
cell carcinoma (RCC) patients because the standard response evaluation criteria for solid tumors (RECIST)
are based on changes of the anatomical tumor dimensions measured by routine CT or MRI imaging during
treatment. These imaging methods captured treatment effects insufficiently because of atypical response
patterns during checkpoint inhibitor-based immunotherapy, the most effective therapy for RCC patients.
Compared to imaging, serum biomarker measurements eliminate radiation exposure to patients, are less
expensive and most importantly, can reflect molecular changes due to therapies early on, sparing patients from
ineffective treatments much sooner than using tumor volume reduction as an indicator. N-glycoproteomic
analyses of sera from patient-derived xenografts (PDXs) represent a new diagram of protein biomarker
discovery that overcomes the most challenging limitation of proteomic profiling based approaches.
Our objective is to identify human-specific N-glycosylated proteins in a mouse background with high
sensitivity using our ccRCC PDX models and validate potential biomarkers associated with tumor volume in
ccRCC patient sera. PDX tumors will be generated from ten ccRCC PDX lines established in our laboratory
using cryopreserved tissues. Tumor tissue and serum will be collected when tumors reach particular volumes
determined by MRI. N-glycoproteomes of PDX sera will be profiled using SAX-ERLIC based enrichment
followed by LC-MS/MS. Peptides identified will be assigned as human-specific, mouse-specific, or human-
mouse conserved and subcellular localization of the human-specific proteins will be determined. Similarly, N-
glycoproteomes of PDX tumor tissues will be profiled and human-specific N-glycoproteins in ccRCC PDX
tissues will be identified. Proteins found in both PDX sera and tumor tissues but not in non-tumor bearing
mouse sera will be compiles and target assays will be developed for the top candidate biomarkers. The levels
of these putative biomarkers in PDX sera and ccRCC patient sera will determined using targeted assays and
their correlation with tumor volumes will be determined in PDX models and ccRCC patients.
Our study represents the first attempt to use ccRCC PDX models to facilitate MS identification of serum
biomarkers. If successful, novel ccRCC-associated protein biomarkers will help reduce the cost of PS and
treatment response assessment, decrease risk of developing second malignancies due to high cumulative
exposure to ionizing radiation during medical imaging, allow early detection of molecular changes associated
with recurrence or therapeutic treatment before clinical symptoms or change in bulk tumor volume, which in
turn will greatly advance clinical management of ccRCC patients with the potential of prolonging survival.
