Abstract 1170: Designing a biomarker-based bedside tool-kit for the clinical evaluation of bladder cancer

Cancer of the urinary bladder (UBC) ranks second in incidence and mortality among the genitourinary cancers causing over 16,000 deaths annually. Currently, the precise diagnosis of bladder cancer involves cystoscopy and cytology, both expensive and painful procedures. Morphologically, malignancies of the bladder can be divided into two subtypes: luminal and basal, which express distinct cytokeratin and stem cell markers and have differing sensitivities to therapy. Although diagnosis based on molecular signatures has the potential to be effective, a verification of their expression in strictly compartmentalized epithelial subtypes is not presently available. The implications of this project are the formation of a bedside tool-kit based on prognostic stem cell biomarkers that can be used following biopsy to efficiently evaluate cancer subtype and provide a preliminary diagnosis. Towards that goal, we analyzed mRNA expression profiles in five established bladder cancer cell lines (RT-4, 5637, T24, HT-1376, 253J), ranging from a grade I (RT-4) to a grade IV cancer cell line (253J). Based on existing literature, these cell lines were classified into either the luminal or basal subtype of bladder cancer. Through RT-PCR and Western Blot studies, genomic expression levels of eleven biomarkers (luminal: UPK, GATA-3, RAB-25, E-Cadherin; and basal: CK-6, p63, CD44S, CD44V, CyclinB1, EGFR, CD49) were analyzed in these cell lines. Cell viability following exposure to two chemotherapy drugs: Gemcitabine and Cisplatin, commonly used to treat bladder cancer, were assayed by colorimetric and clonogenic colony-forming assays. Literature states that though basal cancers are more aggressive, they are paradoxically more sensitive to chemotherapy compared to luminal UBC. Less aggressive/luminal UBC cell lines showed higher mRNA levels for luminal biomarkers, and expressed GATA-3 100% of the time. The more invasive/basal cell lines showed only a slight upregulation of basal biomarkers, but expressed CD44S 100% of the time. Furthermore, MTT Assays showed a significant toxic effect of Gemcitabine on basal cell lines earlier (t=24 hr vs 48/72 hr) than luminal cell lines. However, Cisplatin did not show a significant difference in luminal vs. basal UBC suggesting that the two subtypes of UBC have similar sensitivity to Cisplatin. The study presented here suggests that a PCR-based, biomarker toolkit can aid in an efficient classification of bladder cancers at the bedside, and treatment can be personalized based on the UBC subtype. Citation Format: Isha R. Dabke, Richard Pearce, Georgios Kallifatidis, Balakrishna Lokeshwar. Designing a biomarker-based bedside tool-kit for the clinical evaluation of bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1170.