Xiu-Xian Wu

Expression of autotaxin and acylglycerol kinase in prostate cancer : association with cancer development and progression

Lysophosphatidic acid (LPA) may enhance diverse biologic activities in prostate cancer. This study was conducted to analyze expression levels of LPA‐producing enzymes, autotaxin (ATX) and acylglycerol kinase (AGK), in prostate cancer with relevance to clinicopathological parameters. Real‐time RT‐PCR and western blotting were performed for ATX and AGK in non‐neoplastic prostate cells (PrECs and PrSCs) and prostate cancer cell‐lines (DU‐145, PC‐3, LNCaP, and AILNCaP). Immunohistochemical analyses were conducted in tissue specimens of 132 localized prostate cancer patients who underwent radical prostatectomy between 2001 and 2007 (median observation period, 22 months). Both enzymes were negatively expressed in PrECs and PrSCs at mRNA and protein levels. ATX expression was higher than AGK in AILNCaP, DU‐145, and PC‐3 cell‐lines, while AGK was mainly expressed in LNCaP cells. Immunohistochemically, ATX and AGK expressions were negative in non‐neoplastic epithelia, while both were weakly expressed in the majority of high‐grade intra‐epithelial neoplasia (HG‐PIN). In cancer foci, ATX and AGK expressions were strong in 49% and 62%, weak in 40% and 32%, and negative in 11% and 6%, respectively. Expressions of both enzymes were significantly correlated with primary Gleason grade of cancer foci (P < 0.0001) and capsular invasion (P = 0.03 and 0.003 respectively). ATX expression was significantly correlated with probability of prostate specific antigen (PSA)‐failure after surgery (P < 0.0001). In conclusion, LPA‐producing enzymes (ATX and AGK) were frequently expressed in prostate cancer cells and precancerous HG‐PIN. In particular, high expression levels of ATX were associated with both malignant potentials and poor outcomes. (Cancer Sci 2009; 100: 1631–1638)

Enhancement of TRAIL/Apo2L-mediated apoptosis by adriamycin through inducing DR4 and DR5 in renal cell carcinoma cells.

Renal cell carcinoma (RCC) is one of the most drug‐resistant malignancies in humans. We show that adriamycin (ADR) and TNF‐related apoptosis‐inducing ligand (TRAIL)/Apo2L have a synergistic cytotoxic effect against RCC cells. This synergistic cytotoxicity was obtained in ACHN, A704, Caki‐1 and Caki‐2 human RCC cell lines and freshly derived RCC cells from 6 patients. This synergistic effect, however, was not achieved in 5 samples of freshly isolated normal kidney cells. We further explored the mechanisms underlying this synergistic effect and found that the synergistic cytotoxicity of TRAIL/Apo2L and ADR was realized by inducing apoptosis. Sequential treatment with ADR followed by TRAIL/Apo2L induced significantly more cytotoxicity than the reverse treatment. ADR increased the expression of DR4 and DR5 in RCC cells, but not in the normal kidney cells. Furthermore, the synergistic cytotoxicity was significantly inhibited by DR4:Fc and DR5:Fc fusion proteins, which inhibit TRAIL/Apo2L‐mediated apoptosis. In addition, caspase activity assays and treatment of caspase inhibitors demonstrated that the combination treatment with ADR and TRAIL/Apo2L activated caspase cascade, including caspase‐9, ‐8, ‐6 and ‐3, which were the downstream molecules of death receptors. These findings indicate that ADR sensitizes RCC cells to TRAIL/Apo2L‐mediated apoptosis through induction of DR4 and DR5, suggesting that the combination therapy of TRAIL/Apo2L and ADR might be effective for RCC therapy.

TRAIL and chemotherapeutic drugs in cancer therapy.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL/Apo2L) is a recently identified member of the TNF ligand family that selectively induces apoptosis in tumor cells in vitro and in vivo but not in most normal cells. Chemotherapeutic drugs induce apoptosis and the upregulation of death receptors or activation of intracellular signaling pathways of TRAIL. Numerous chemotherapeutic drugs have been shown to sensitize tumor cells to TRAIL-mediated apoptosis. Studies from our laboratory have also shown that TRAIL-resistant renal cell carcinoma, prostate gland cancer, and bladder cancer cells are sensitized by subtoxic concentrations of chemotherapeutic drugs including doxorubicin, epirubicin, pirarubicin, and cisplatin. TRAIL, particularly in combination with chemotherapeutic agents, is thus potentially promising in the treatment of cancer. This review addresses the putative role of TRAIL in cancer treatment and discusses the molecular basis of the synergistic effect of TRAIL and chemotherapeutic drugs.

Gene expression profiles of lysophosphatidic acid-related molecules in the prostate: relevance to prostate cancer and benign hyperplasia.

To elucidate gene expression profiles of lysophosphatidic acid (LPA)‐related molecules in cancer, pre‐cancerous lesion, and benign hyperplasia of the prostate.

Low concentrations of doxorubicin sensitizes human solid cancer cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-receptor (R) 2-mediated apoptosis by inducing TRAIL-R2 expression.

There is accumulating evidence suggesting that tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL)‐receptor (R) 2 is a promising molecular target for cancer therapy. Therefore, we investigated the effect of chemotherapeutic agents on TRAIL‐R2‐mediated apoptosis and cytotoxicity in various human solid cancer cells. Treatment of the ACHN human renal cell carcinoma (RCC) cell line with agonistic TRAIL‐R2 antibody (lexatumumab) in combination with 5‐fluorouracil, vinblastine, paclitaxel, or docetaxel did not overcome resistance to these agents. However, treatment with lexatumumab in combination with doxorubicin had a synergistic cytotoxicity. Synergy was also achieved in two other human RCC cell lines, Caki‐1 and Caki‐2, and in eight primary RCC cell cultures. Sequential treatment with doxorubicin followed by lexatumumab induced significantly more cytotoxicity than reverse treatment or simultaneous treatment. Low concentrations of doxorubicin (0.1 and 1 µg/mL) significantly increased TRAIL‐R2 expression at both the mRNA and protein levels. Furthermore, the combination of doxorubicin and lexatumumab significantly enhanced caspase 8 activity, Bid cleavage, Bcl‐xL decrease, release of cytochrome c, and caspase 9 and caspase 3 activity, and induced synergistic apoptosis. The activation of caspases and apoptosis induced with lexatumumab and doxorubicin was blocked by the human recombinant DR5:Fc chimeric protein. In addition, synergistic cytotoxicity was also observed in human prostate, bladder, and lung cancer cells, but was inhibited by the DR5:Fc chimeric protein. These findings suggest that doxorubicin sensitizes solid cancer cells to TRAIL‐R2‐mediated apoptosis by inducing TRAIL‐R2 expression, and that the combination treatment with lexatumumab and doxorubicin might be a promising targeted therapy for cancers, including RCC, prostate, bladder, and lung cancers. (Cancer Sci 2007; 98: 1969–1976)

Expression and Secretion of N-acylethanolamine-hydrolysing Acid Amidase in Human Prostate Cancer Cells

N-acylethanolamines (NAEs) are a class of bioactive lipid molecules in animal tissues, including the endocannabinoid anandamide and the anti-inflammatory substance N-palmitoylethanolamine. Enzymatic hydrolysis of NAEs is considered to be an important step to regulate their endogenous levels. Lysosomal NAE-hydrolysing acid amidase (NAAA) as well as fatty acid amide hydrolase (FAAH) is responsible for this reaction. Here, we report relatively high expression of NAAA in human prostate cancer cells (PC-3, DU-145 and LNCaP) and prostate epithelial cells (PrEC), with the highest mRNA level in LNCaP cells. FAAH and the NAE-forming enzyme N-acylphosphatidylethanolamine-hydrolysing phospholipase D (NAPE-PLD) were also detected in these cells. NAAA activity in LNCaP cells could be distinguished from coexisting FAAH activity, based on their different pH dependency profiles and specific inhibition of FAAH activity by URB597. These results showed that both the enzymes were functionally active. We also found that NAAA was partly secreted from LNCaP cells, which underlined possible usefulness of this enzyme as a biomarker of prostate cancer.

Enhancement of Lexatumumab-Induced Apoptosis in Human Solid Cancer Cells by Cisplatin in Caspase-Dependent Manner

Purpose: This study was designed to evaluate the apoptotic effect of mapatumumab or lexatumumab, human agonistic antibodies that target the tumor necrosis factor–related apoptosis-inducing ligand receptor 1 (TRAIL-R1) and receptor 2 (TRAIL-R2), in combination with chemotherapeutic agents, against human solid cancer cells. Experimental Design: Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Synergy was assessed by isobolographic analysis. Results: Treatment of ACHN human renal cell carcinoma cells with cisplatin combined with mapatumumab did not overcome resistance to these agents. However, treatment with cisplatin in combination with lexatumumab had a synergistic cytotoxicity. Synergy was also achieved in six primary renal cell carcinoma cell cultures. Lexatumumab and cisplatin also synergistically enhanced apoptosis. Pretreatment with cisplatin followed by lexatumumab resulted in high cytotoxicity compared with the reverse sequence. Cisplatin significantly increased TRAIL-R2 expression at both the mRNA and the protein levels. Furthermore, the combination of lexatumumab and cisplatin significantly enhanced caspase-8 activity, Bid cleavage, up-regulation of Bax, cytochrome c release, and caspase-9, caspase-6, and caspase-3 activities. Importantly, the activation of caspase-8 was significantly abrogated by the specific inhibitors of caspase-9, caspase-6, and caspase-3. Furthermore, combination-induced cytotoxicity was significantly suppressed by the DR5:Fc chimeric protein and the specific inhibitors of caspase-8, caspase-9, caspase-6, and caspase-3. A similar effect was observed in prostate cancer, bladder cancer, lung cancer, and cervical cancer cells. Conclusions: Cisplatin sensitizes solid cancer cells to lexatumumab-induced apoptosis by potentiation of the extrinsic and intrinsic apoptotic pathways that lead to amplification of caspase activation, particularly caspase-8, suggesting the combination treatment of solid cancers with cisplatin and lexatumumab might overcome their resistance.

Expression of TRAIL, DR4, and DR5 in Bladder Cancer: Correlation With Response to Adjuvant Therapy and Implications of Prognosis

OBJECTIVES To explore the interrelationship of human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its death receptors DR4 and DR5 expressions level with patient prognosis and the response to adjuvant therapy in bladder cancer, the synergism function that is between chemotherapy and TRAIL on apoptosis induction in tumor cells. METHODS The expression of TRAIL, DR4, and DR5 was studied using immunohistochemistry of paraffin-embedded tumor specimens from 229 bladder cancer patients who had undergone transurethral resection. RESULTS Cytoplasmic TRAIL, DR4, and DR5 expressions were detected in 35%, 75.1%, and 74.2% of bladder cancer patients, respectively. Patients with bladder cancer with either high DR4 or DR5 expression had a significantly longer postoperative recurrence-free rate than those with low expression of both during the 10-year follow-up. Multivariate analysis revealed that the expression of DR4 (P < .001), DR5 (P < .001) and epirubicin therapy (P = .034) were independent prognostic indicators of bladder cancer. Furthermore, epirubicin therapy significantly improved recurrence-free rate for the patients with DR4-high (P = .006) or DR5-high (P = .042) tumor. CONCLUSIONS The results of the present study have shown for the first time that a combination of DR4 and DR5 expression have significant value in predicting the prognosis of bladder cancer. In addition, patients with high expression of both DR4 and DR5 might benefit from epirubicin therapy.

Telomerase activity in urine after transurethral resection of superficial bladder cancer and early recurrence

Background : To explore the relationship between telomerase activity in urine after transurethral resection (TUR) of superficial bladder cancer and early intravesical recurrence.

Increased intracellular doxorubicin by anti-Fas monoclonal antibody: a mechanism that enhances the cytotoxicity in renal cell carcinoma cells

OBJECTIVES To investigate the effect of anti-Fas monoclonal antibody (mAb) on the intracellular concentration of doxorubicin in renal cell carcinoma (RCC) cells. Little is known about the influence of anti-Fas mAb on the intracellular concentration of chemotherapeutic agents. METHODS The concentration of intracellular doxorubicin was determined by high-performance liquid chromatography. The mRNA and protein levels of multidrug resistance-associated protein gene were evaluated by reverse transcriptase-polymerase chain reaction and immunocytochemistry, respectively. RESULTS An increased concentration of doxorubicin inside the cells was found: 2.4-fold in ACHN cells (a human RCC cell line) after treatment with doxorubicin combined with anti-Fas mAb compared with doxorubicin alone. Of the five cases of freshly derived RCC cells treated with doxorubicin and anti-Fas mAb, the intracellular concentration of doxorubicin was increased 2.3 and 2.7-fold in two of them, respectively. Furthermore, both the mRNA and the protein levels of the multidrug resistance-associated protein gene were downregulated after treatment of ACHN cells with anti-Fas mAb. Treatment of ACHN cells with a combination of anti-Fas mAb and doxorubicin resulted in a potentiation of the doxorubicin-mediated cytotoxicity. CONCLUSIONS The increased intracellular concentration of doxorubicin by anti-Fas mAb might be one of the mechanisms responsible for the enhancement of doxorubicin-mediated cytotoxicity in RCC cells.