Microdissection for detecting genetic aberrations in early and advanced human urinary bladder cancer

Laser microdissection is an essential method for the investigation of the multistep carcinogenic process in the urinary bladder. Reliable detection of tumor-specific alterations which can be compromised by the presence of normal cells, requires microdissection of pure tumor cell populations (>80%) to detect loss of heterozygosity (LOH) by either fluorescence in situ hybridization (FISH) or sequence analysis. Multiple molecular methods need to be performed in the course of studying often-small lesions. This chapter describes in detail the use of laser microdissection, whole-genome amplification by improved primer extension preamplification (I-PEP)-polymerase chain reaction, and subsequent LOH, FISH, and sequencing analysis in the investigation of urothelial tumors and their precursor lesions. The combination of the described methods allows a wide spectrum of molecular investigations of tumor cells and helps to understand the fundamental alterations involved in urothelial carcinogenesis.