Differential expression of SLITRK6 gene as a potential therapeutic target for urothelial carcinoma in particular upper tract cancer

Background: Urinary bladder urothelial carcinoma (UBUC) and upper tract urothelial carcinoma (UTUC) harbor analogous morphology with comparable cytogenetic changes as well as prognostic factors but their similar biological activities still remain controversial. SLITRK6 gene has been demonstrated to have distinct role in urothelial cancers with a distinction between UTUC and UBUC.

Method: The study included a total of 80 patients of urothelial carcinoma including 60 UBUC and 20 UTUC cases. The tumor tissues from both the groups were evaluated for gene expression at mRNA level by qRT-PCR, and protein expression by immunohistochemistry (IHC) and western blot.

Results: Significantly more than 4-fold high mRNA expression of SLITRK6 was observed in UTUC against 1.2-fold in UBUC (p < 0.0001). The overall SLITRK6 expression by IHC was observed in 80% of the UBUC cases in comparison to 100% strong expression in UTUC patients and among two groups expression exhibited a significant difference for moderate to strong expression (p = 0.0005). The protein expression by western blot analysis in UTUC samples was considerably higher as compared to UBUC samples (1.64 vs. 0.76 respectively: p = 0.01). A strong concordance exhibited for the higher mRNA and protein expression in both UTUC and UBUC cases (∼75%) wherein 80%, 75% and 70% higher expression of SLITRK6 was detected by qRT-PCR, Western blot and IHC respectively.

Conclusion: To conclude, although SLITRK6 exhibits a strong expression in both UTUC and UBUC but was considerably observed higher in majority of UTUC cases. Therefore, SLITRK6 appears as a promising novel possible gene target for urothelial carcinoma in particular UTUC.