Kanimoto Y

CCR1/CCL5 interaction promotes invasion of taxane-resistant PC3 prostate cancer cells by increasing secretion of MMPs 2/9 and by activating ERK and Rac signaling

Castration-refractory prostate cancer (CRPC) is treated with taxane-based chemotherapy, but eventually becomes drug resistant. It is thus essential to identify novel therapeutic targets for taxane resistance in CRPC patients. We investigated the role of the chemokine (C-C motif) receptor 1 (CCR1) and its ligand, chemokine (C-C motif) ligand 5 (CCL5), in taxane-resistant CRPC using paclitaxel-resistant prostate cancer cells (PC3PR) established from PC3 cells. We found that the expression levels of CCR1 mRNA and protein were up-regulated in PC3PR cells compared to PC3 cells. In order to investigate the role of increased CCR1 in PC3PR cells, we stimulated cells with CCL5, one of the chemokine ligands of CCR1. In CCL5-stimulated PC3PR cells, siRNA-mediated knockdown of CCR1 expression reduced phosphorylation of ERK1/2 and Rac1/cdc42. Furthermore, CCR1 knockdown and MEK1/2 inhibition decreased CCL5-stimulated secretion of MMPs 2 and 9, which play important roles in cancer cell invasion and metastasis. In the Matrigel invasion assay, knockdown of CCR1 and inhibition of the ERK and Rac signaling pathways significantly decreased the number of invading cells. Finally, the serum CCL5 protein level as measured by ELISA was not different among the three groups of patients: those with negative prostate biopsy, those at initial diagnosis of prostate cancer, and those with taxane-resistant prostate cancer. These results demonstrated for the first time that the interaction of CCR1 with CCL5 caused by increased expression of CCR1 promotes invasion of PC3PR cells by increasing secretion of MMPs 2 and 9 and by activating ERK and Rac signaling. Our findings suggest that CCR1 could be a novel therapeutic target for taxane-resistant CRPC.

Serum exosomal P-glycoprotein is a potential marker to diagnose docetaxel resistance and select a taxoid for patients with prostate cancer

OBJECTIVES Docetaxel is used as the first-line chemotherapy for castration-resistant prostate cancer (CRPC), but docetaxel resistance occurs in part owing to induction of P-glycoprotein (P-gp) encoded by multidrug resistance protein 1 (MDR1) gene. A recently developed taxane-cabazitaxel-has poor affinity for P-gp and is thereby effective in docetaxel-resistant CRPC. It has been recently demonstrated that exosomes in the body fluids could serve as a diagnostic marker because they contain proteins and RNAs specific to the cells from which they are derived. In this study, we aimed to investigate if P-gp in blood exosomes could be a marker to diagnose docetaxel resistance and select a taxoid for patients with CRPC. METHODS AND MATERIALS Exosomes were isolated by differential centrifugation from docetaxel-resistant prostate cancer (PC-3) cells (PC-3R) and their parental PC-3 cells and from the serum of patients. Silencing of P-gp was performed by small interfering RNA transfection. Protein expression was examined by Western blot analysis. Viability of cells treated with docetaxel or cabazitaxel was determined by water soluble tetrazolium salt (WST) assay. RESULTS The level of P-gp was higher in exosomes as well as cell lysates from PC-3R cells than in those from PC-3 cells. Cabazitaxel effectively killed PC-3R cells, and MDR1 knockdown improved the sensitivity of PC-3R cells to docetaxel but not to cabazitaxel. The P-gp level in blood exosomes was relatively higher in clinically docetaxel-resistant patients than in therapy-naïve patients. CONCLUSIONS Our results suggest that detection of P-gp in blood exosomes, which is involved in resistance to docetaxel but not to cabazitaxel, could be useful to diagnose docetaxel resistance and select an appropriate taxoid for patients with CRPC-docetaxel or cabazitaxel.

Randomized Controlled Study of the Efficacy, Safety and Quality of Life with Low Dose bacillus Calmette-Guérin Instillation Therapy for Nonmuscle Invasive Bladder Cancer

PURPOSE The optimal dose of intravesical bacillus Calmette-Guérin for the treatment of nonmuscle invasive bladder cancer is controversial. We investigated if induction therapy with low dose bacillus Calmette-Guérin could achieve a complete response rate similar to that of standard dose bacillus Calmette-Guérin, with less toxicity and higher quality of life. MATERIALS AND METHODS After transurethral resection, patients with unresectable multiple nonmuscle invasive bladder cancer and/or carcinoma in situ were randomized to receive standard (80 mg) or low dose (40 mg) bacillus Calmette-Guérin instillation induction therapy (weekly, 8 times). The primary end point was noninferiority of low dose bacillus Calmette-Guérin with a null hypothesis of a 15% decrease in complete response rate. Secondary end points were recurrence-free survival, progression-free survival, overall survival, patient compliance, adverse events and quality of life using the EORTC QLQ-C30. RESULTS In an intent to treat analysis of 166 patients the complete response rates for low dose and standard dose bacillus Calmette-Guérin were 79% (95% CI 0.70-0.88) and 85% (95% CI 0.77-0.92), respectively. Dunnett-Gent analysis revealed that the null hypothesis of inferiority of low dose bacillus Calmette-Guérin in terms of complete response could not be rejected (p = 0.119). However, there were no significant differences between the groups in terms of recurrence, progression and overall survival. Low dose bacillus Calmette-Guérin was associated with significantly less fever (p = 0.001) and micturition pain (p = 0.047), and significantly higher quality of life scores for global quality of life, role functioning and functional impairment. CONCLUSIONS The noninferiority of low dose bacillus Calmette-Guérin was not proven. However, low dose bacillus Calmette-Guérin was associated with lower toxicity and higher quality of life compared to standard dose bacillus Calmette-Guérin in patients with nonmuscle invasive bladder cancer.

Studies on the Phagocytic function of Urinary Leukocytes

Urine specimens from patients with urinary tract infection (UTI) were examined to determine the rate of phagocytosis and viability of urinary leukocytes. The phagocytic function of urinary leukocytes was also studied in vitro. The mean rate of viable urinary leukocytes was 83 per cent and the phagocytic potency was confirmed by light and electron microscopic studies. In 99 per cent of 113 patients with UTI, urinary leukocytes were shown to have phagocytized bacteria. The rate of phagocytosis in chronic UTI was higher than that in acute UTI. Urinary osmotic pressure and the positive or negative of antibody coated bacteria were supposed to be factors influencing phagocytic potency of urinary leukocytes.