CD44v8-10 mRNA contained in serum exosomes as a diagnostic marker for docetaxel resistance in prostate cancer patients

Abstract

Background: Docetaxel is first-line chemotherapy for castration-resistant prostate cancer (CRPC), but most patients acquire docetaxel resistance. CD44 has been shown to be involved in drug resistance of cancers including prostate cancer. We hypothesized that CD44 in serum exosomes could be a diagnostic marker for docetaxel resistance in CRPC patients. In this study, we examined CD44 protein and mRNA expression in cell lysates and exosomes isolated from prostate cancer cells, evaluated the effect of CD44v8-10 knockdown on docetaxel sensitivity and measured CD44 mRNA copy numbers contained in serum exosomes in prostate cancer patients. Materials and methods: Docetaxel-sensitive PC-3 prostate cancer cells and docetaxel-resistant PC-3R cells established previously from parental PC-3 cells were used. CD44v8-10 knockdown was performed by siRNA transfection. Blood was collected from 50 docetaxel-naïve and 10 docetaxel-resistant patients and 15 control males. CD44 protein expression was evaluated by Western blotting. CD44 mRNA expression was measured by RT-digital PCR.Results: The levels of CD44v8-10 protein and mRNA in cell lysates and exosomes were higher in PC-3R cells than in PC-3 cells. CD44v8-10 knockdown significantly increased docetaxel sensitivity of PC-3R cells. The CD44v8-10 mRNA copy numbers in serum exosomes were higher in docetaxel-resistant patients than in docetaxel-naïve patients and control males (median 46, 12 and 17 copies/mL serum, respectively, P ¼ 0.032). In contrast, the serum exosomal mRNA copy numbers of CD44 standard isoform (CD44s) were not different among 3 groups (median 25, 14 and 13 copies/mL serum, respectively, P ¼ 0.150). Conclusions: CD44v8-10 may be involved in docetaxel resistance in prostate cancer and serum exosomal CD44v8-10 mRNA could be a diagnostic marker for docetaxel-resistant CRPC.

Validation of common reference genes stability in exosomal mRNA‐isolated from liver and breast cancer cell lines

“…Thus, it is necessary to find and select suitable reference genes before each relative gene expression analysis by RT‐qPCR. Although several reports investigating stable miRNAs in exosomes derived from different types of cells and tissues under varied conditions (Gouin et al, 2017; Li et al, 2015), the relative expression of exosomal mRNAs was analyzed using common reference genes such as GAPDH , often without evaluating their stability in exosomes (Kato et al, 2020; Rowland et al, 2019; Xu et al, 2018). Here, we analyzed the stability of several reference genes in exosomes derived from four cancer cell lines by five different and useful mathematical algorithms namely geNorm, BestKeeper, NormFinder, Delta Ct and RefFinder.…”

A Comprehensive Review on Factors Influences Biogenesis, Functions, Therapeutic and Clinical Implications of Exosomes

“… 259 Kato et al analyzed the expression of CD44 protein and mRNA from cell lysates and exosomes from prostate cancer cells. 260 Exosomes from serum containing CD44v8-10 mRNA was used as a diagnostic marker for docetaxel resistance in prostate cancer patients. The study was performed to evaluate plasma exosomal mRNA-125a-5p and miR-141-5p miRNAs as biomarkers for the diagnosis of prostate cancer from 19 healthy individuals and 31 prostate cancer patients.…”

CD44 and Tumor-Derived Extracellular Vesicles (TEVs). Possible Gateway to Cancer Metastasis

“…The concept of tumor cell intravasation involves the ability of cancer cells to invade into the normal tissue, often towards lymphatic or blood vessel, and then cross the endothelial barrier to enter circulation [ 87 ]. This process involves many different factors, including the presence of other cells in the tumor microenvironment, signaling molecules, proteases, and the proper environmental conditions at the tumor site and vasculature.…”