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Although cisplatin‐based chemotherapy is considered to be the treatment of choice for metastatic bladder cancer, its efficacy and tolerability has proven to be limited. MicroRNAs are small noncoding RNAs, whose genes are frequently organized in clusters. These molecules constitute posttranscriptional regulators of mRNA expression and are claimed to be deregulated in cancer. miR‐143/145 and miR‐183/96/182 clusters have been extensively studied in bladder cancer cells. Herein, we tried to add up to this knowledge by assessing the expression levels of the five mature microRNAs derived from the aforementioned clusters in T24 bladder cancer cells exposed to either cisplatin or paclitaxel. For both compounds, the viability of treated T24 cells was estimated via the MTT colorimetric assay and the Trypan Blue exclusion method, while a fraction of the cells was left to recover. The expression levels of all mature microRNAs were finally quantified both in treated and in recovered cells by performing real‐time PCR. According to our data, cisplatin and paclitaxel strongly decreased T24 cells' viability, showing in parallel the ability to significantly down‐regulate miR‐143 levels, and up‐regulate the expression levels of miR‐145, miR‐183, miR‐96, and miR‐182, which, in their total, demonstrated case‐specific variations after recovery period.

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The vast majority of malignancies detected in renal parenchyma are diagnosed as renal cell carcinoma (RCC), whose subtype discrimination and determination of prognosis may contribute to the selection of the adequate therapy. Recently, a new class of small non-coding RNAs, known as microRNAs, has proven to be among the most promising biomarkers for providing this information. Herein, we sought to add up to this knowledge by evaluating the expression levels of microRNA-145 (miR-145) in RCC. For that purpose, total RNA from 58 cancerous and 44 adjacent non-cancerous renal tissues was firstly extracted and then polyadenylated and reverse transcribed to cDNA. MiR-145 levels were finally analyzed by developing and applying a highly sensitive real-time PCR protocol, while their clinical significance was determined via comprehensive statistical analysis. Our data showed that miR-145 was significantly downregulated in cancerous samples and could discriminate between clear cell and non-clear cell subtypes. Moreover, miR-145 expression was found to be correlated with primary tumor staging of cancerous samples, something also noticed in the clear cell RCC subset, in which miR-145 levels were negatively correlated with tumor size as well. Overall, these results indicate that miR-145 might constitute a promising molecular marker for RCC classification and staging.

Bladder and renal cancer are two representative cases of tumors that respond differentially to gemcitabine. Previous studies have shown that gemcitabine can trigger apoptosis in various cancer cells. Herein, we sought to investigate the impact of gemcitabine on the expression levels of the BCL2 family members BCL2, BAX, and BCL2L12 and the apoptosis-related microRNAs miR-182, miR-96, miR-145, and miR-16 in the human bladder and kidney cancer cell lines T24 and Caki-1, respectively. Cancer cells' viability as well as the IC50 doses of gemcitabine were estimated by the MTT assay, while the detection of cleaved PARP via Western blotting was used as an indicator of apoptosis. Furthermore, T24 and Caki-1 cells' ability to recover from treatment was also monitored. Two different highly sensitive quantitative real-time RT-PCR methodologies were developed in order to assess the expression levels of BCL2 family genes and microRNAs. Exposure of cancer cells to gemcitabine produced the IC50 values of 30 and 3 nM for Caki-1 and T24 cells, correspondingly, while cleaved PARP was detected only in Caki-1 cells. T24 cells demonstrated the ability to recover from gemcitabine treatment, whereas Caki-1 cells' recovery capability was dependent on the initial time of exposure. BCL2 and BAX were significantly modulated in treated Caki-1 cells. Instead, T24 cells exhibited alterations only in the latter, as well as in all studied microRNAs. Therefore, according to our data, bladder and renal cancer cells' response to gemcitabine is accompanied by distinct alterations in the expression levels of their apoptosis-related genes and microRNAs.