Introduction: Lin-11, Isl-1 and Mec-3 domains (LIM) homeobox genes are among the most important sub-families of homeobox genes. These genes are thought to play an important role in cancer. In this study, the protein expression of these genes was examined in urothelial carcinoma of the bladder. The expression pattern of Islet-1 (ISL1) and LIM homeobox 5 (LHX5) across different cancer stages and grades, as well as the association between the protein expression of these genes and patient demographics and clinicopathological features, were examined. Methods: A total of 100 formalin-fixed paraffin-embedded urothelial carcinoma tissues were selected from the Department of Pathology, Hospital Kuala Lumpur and the protein expression of ISL1 and LHX5 was determined using immunohistochemistry. Results: Positive expression of ISL1 and LHX5 was detected in 94% and 98% of the samples, respectively. There were no distinct LHX5 expression patterns associated with different cancer stages, but the proportion of high-expressing tumours was higher in high-grade tumours. In addition, there was a significant association between the expression of LHX5 and tumour grade. The proportion of tumours expressing high levels of ISL1 was found to be highest in later stage tumours. Conclusion: The high percentage of tumours expressing both these genes suggests that ISL1 and LHX5 play an important role in bladder tumourigenesis across multiple stages.

Urothelial carcinoma is a common malignant neoplasm that has a poor prognosis and a high frequencyof recurrence and metastasis. Constant disease surveillance with periodic and long term cystoscopyexamination is necessary for management of the disease. However, the monitoring and therapyregimen is expensive, incurring a massive burden to patients and the government. Therefore, thedevelopment of specific biomarkers for urothelial carcinoma at an early stage and recurrence detectionbecomes a priority. Homeobox genes are a family of genes that are involved in tumourigenesis.They might be potential prognostic markers for urothelial carcinoma. The study investigated theexpression pattern of NANOG which is one of a homeobox gene in different stages and grades ofurothelial carcinoma. NANOG expressions were also correlated with patient demographic factors andclinicopathological parameters. The expression of NANOG in 100 formalin-fixed paraffin-embeddedurothelial carcinoma tissues was determined by immunohistochemistry. Immunohistochemistryshowed positive expression of NANOG in all specimens with detection in the cytoplasm, nucleiand the nuclear membrane of the cancer cells. The immunohistochemical expression of NANOGincreased across stages and grades of the tumour. The expression of NANOG was not significantlyassociated with demographic factors; gender (p = 0.376), race (p = 0.718) and age (p = 0.058) aswell as with most of the clinicopathological parameters; pathological stage (p = 0.144), grade (p =0.625), lymph node involvement (p = 0.174) and distant metastasis (p = 0.228). However, NANOGexpression showed significant correlation with tumour invasion (p = 0.019). We concluded thatNANOG might be a potential biomarker for early diagnosis of urothelial carcinoma of the bladder.