8-Methoxy-α-lapachone and lawsone: antiproliferative effects on bladder tumour cells

Quinones are chemical compounds produced from the oxidation of phenols. Among the quinones, naphthoquinones stand out as potential antitumor agents. Bladder tumour is the tenth most diagnosed in the world. Based on this, using a urothelial carcinoma cell line (T24), two naphthoquinones had their cytotoxicity tested by the MTT colorimetric method and were submitted to assays of clonogenic survival, morphology, cell cycle, cell migration and species reactive oxygen. The results showed 8-methoxy-α-lapachone and lausone presented selectivity indexes (19.5 and 28.0, respectively) for T24 cells. Moreover, the two naphthoquinones reduced the cell viability, interfered with the process of cell migration, changed the cell cycle kinectics and induced the production of species reactive oxygen (ROS). Additionaly, 8-methoxy-α-lapachone altered the morphology of the cells. In conclusion, the studied naphthoquinones showed potential antiproliferative effects in bladder cancer cells, interfering in cellular processes, possibly through oxidative stress.

Melatonin-Assisted Cisplatin Suppresses Urinary Bladder Cancer Cell Proliferation and Growth through Inhibiting PrP(C)-Regulated Cell Stress and Cell Proliferation Signaling

This study investigated whether melatonin (Mel) would promote cisplatin to suppress the proliferation and growth of bladder cancer (BC) cells by inhibiting cellular prion protein (PrP^C)-mediated cell stress and cell proliferation signaling. An immunohistochemical staining of tissue arrays from BC patients demonstrated that the PrP^C expression was significantly upregulated from stage I to III BC (p < 0.0001). The BC cellline of T24 was categorized into G1 (T24), G2 (T24 + Mel/100 μM), G3 (T24+cisplatin/6 μM), G4 (PrP^C overexpression in T24 (i.e., PrP^C-OE-T24)), G5 (PrP^C-OE-T24+Mel), and G6 (PrP^C-OE-T24+cisplatin). When compared with a human uroepithelial cell line (SV-HUC-1), the cellular viability/wound healing ability/migration rate were significantly increased in T24 cells (G1) and further significantly increased in PrP^C-OE-T24 cells (G4); and they were suppressed in Mel (G2/G5) or cisplatin (G3/G6) treatment (all p < 0.0001). Additionally, the protein expressions of cell proliferation (PI3K/p-Akt/p-m-TOR/MMP-9/PrP^C), cell cycle/mitochondrial functional integrity (cyclin-D1/clyclin-E1/ckd2/ckd4/mitochondrial-cytochrome-C/PINK1), and cell stress (RAS/c-RAF/p-MEK1/2, p-ERK1/2) markers showed a similar pattern of cell viability among the groups (all p < 0.001). After the BC cell line of UMUC3 was implanted into nude mouse backs, by day 28 mthe BC weight/volume and the cellular levels of PrP^C/MMP-2/MMP-9 were significantly, gradually reduced from groups one to four (all p < 0.0001). The protein expressions of cell proliferation (PI3K/p-Akt/p-m-TOR/MMP-9/PrP^C), cell cycle/mitophagy (cyclin-D1/clyclin-E1/ckd2/ckd4/PINK1), and cell stress (RAS/c-RAF/p-MEK1,2/p-ERK1,2) signaling were significantly, progressively reduced from groups one to four, whereas the protein expressions of apoptotic (Mit-Bax/cleaved-caspase-3/cleaved-PARP) and oxidative stress/mitochondrial damaged (NOX-1/NOX-2/cytosolic-cytochrome-C/p-DRP1) markers expressed an opposite pattern of cell proliferation signaling among the groups (all p < 0.0001). Mel-cisplatin suppressed BC cell growth/proliferation via inhibiting the PrP^C in upregulating the cell proliferation/cell stress/cell cycle signaling.

Aloperine Prevents Migration, Invasion, and Adhesion by Upregulating TIMP-4 in Human Bladder Cancer Cells

BACKGROUND

Aloperine (ALO) is an important active component of quinolizidine alkaloids in Sophora flavescens A and Sophora alopecuroides L, and has effective anticancer activity against multiple cancers. However, the influence and mechanism of ALO on migration, invasion, and adhesion in bladder cancer cells remain unclear.

OBJECTIVE

The aim of this study is to determine the anticancer effect of ALO on migration, invasion, and adhesion in bladder cancer cells and to investigate its potential TIMP-4-related mechanism.

METHODS

Cell viability, cytotoxicity, wound healing, Transwell invasion, cell adhesion, real-time qPCR, western blot, and ELISA assays were performed to analyze the effect of ALO on migration, invasion, and adhesion in bladder cancer 5637 and UM-UC-3 cells. Furthermore, the anti-TIMP-4 antibody was used to explore the potential effect on ALO-inhibited bladder cancer cells.

RESULTS

We have found that ALO significantly suppressed migration, invasion, and adhesion in bladder cancer cells. Furthermore, ALO could downregulate the expression of MMP-2 and MMP-9 mRNAs and proteins, and increase the expression of TIMP-4 mRNA and protein. Moreover, the anti-TIMP-4 antibody reversed the prevention of migration, invasion, and adhesion in ALO-treated bladder cancer cells.

CONCLUSION

The data in this study suggest that ALO suppressed migration, invasion, and adhesion in bladder cancer cells by upregulating the expression of TIMP-4.

Rosa hybrida Petal Extract Exhibits Antitumor Effects by Abrogating Tumor Progression and Angiogenesis in Bladder Cancer Both In Vivo and In Vitro

The edible Rosa hybrida (RH) petal is utilized in functional foods and cosmetics. Although the biological function of RH petal extract is known, mechanism of action studies involving tumor-associated angiogenesis have not yet been reported. Herein, we investigated the regulatory effect of the ethanol extract of RH petal (EERH) on tumor growth and tumor angiogenesis against bladder cancer. EERH treatment inhibited the bladder carcinoma T24 cell and 5637 cell proliferation because of G₁-phase cell cycle arrest by inducing p21WAF1 expression and reducing cyclins/CDKs level. EERH regulated signaling pathways differently in both cells. EERH-stimulated suppression of T24 and 5637 cell migration and invasion was associated with the decline in transcription factor-mediated MMP-9 expression. EERH oral administration to xenograft mice reduced tumor growth. Furthermore, no obvious toxicity was observed in acute toxicity test. Decreased CD31 levels in EERH-treated tumor tissues led to examine the angiogenic response. EERH alleviated VEGF-stimulated tube formation and proliferation by downregulating the VEGFR2/eNOS/AKT/ERK1/2 cascade in HUVECs. EERH impeded migration and invasion of VEGF-induced HUVECs, which is attributed to the repressed MMP-2 expression. Suppression of neo-microvessel sprouting, induced by VEGF, was verified by treatment with EERH using the ex vivo aortic ring assay. Finally, kaempferol was identified as the main active compound of EERH. The present study demonstrated that EERH may aid the development of antitumor agents against bladder cancer.

Hybrid Nanoparticles as an Efficient Porphyrin Delivery System for Cancer Cells to Enhance Photodynamic Therapy

Photodynamic therapy (PDT) is a potential non-invasive approach for application in oncological diseases, based on the activation of a photosensitizer (PS) by light at a specific wavelength in the presence of molecular oxygen to produce reactive oxygen species (ROS) that trigger the death tumor cells. In this context, porphyrins are interesting PS because they are robust, have high chemical, photo, thermal, and oxidative stability, and can generate singlet oxygen (1O2). However, porphyrins exhibit low solubility and a strong tendency to aggregate in a biological environment which limits their clinical application. To overcome these challenges, we developed hybrid nanostructures to immobilize 5,10,15,20-tetrakis[(4-carboxyphenyl) thio-2,3,5,6-tetrafluorophenyl] (P), a new third-generation PS. The biological effect of this system was evaluated against bladder cancer (BC) cells with or without light exposition. The nanostructure composed of lipid carriers coated by porphyrin-chitosan (P-HNP), presented a size of ca. 130 nm and low polydispersity (ca. 0.25). The presence of the porphyrin-chitosan (P-chitosan) on lipid nanoparticle surfaces increased the nanoparticle size, changed the zeta potential to positive, decreased the recrystallization index, and increased the thermal stability of nanoparticles. Furthermore, P-chitosan incorporation on nanoparticles increased the stability and enhanced the self-organization of the system and the formation of spherical structures, as observed by small-angle X-ray scattering (SAXS) analysis. Furthermore, the immobilization process maintained the P photoactivity and improved the photophysical properties of PS, minimizing its aggregation in the cell culture medium. In the photoinduction assays, the P-HNP displayed high phototoxicity with IC50 3.2-folds lower than free porphyrin. This higher cytotoxic effect can be correlated to the high cellular uptake of porphyrin immobilized, as observed by confocal images. Moreover, the coated nanoparticles showed mucoadhesive properties interesting to its application in vivo. Therefore, the physical and chemical properties of nanoparticles may be relevant to improve the porphyrin photodynamic activity in BC cells.

Effects of targeted Notch1 silencing on the biological processes of the T24 and 5637 cells in vitro

The present study aimed to investigate the roles of Notch1 in the biological processes of bladder cancer cells (BCCs) in vitro. Short hairpin (sh)RNA targeting Notch1 was designed and constructed, and the T24 and 5637 BCCs were selected for transfection. The cells were classified into two groups: shRNA negative control (NC) and Notch1 shRNA. MTT and Transwell assays, and flow cytometry were performed to examine the changes in cell proliferation, invasiveness, and apoptosis, respectively. In addition, reverse transcription-quantitative PCR and western blot analysis was used to detect the mRNA and protein expression levels of apoptosis-related proteins (Bax, Bid and Bcl2) and epithelial-mesenchymal transition factors (vimentin and E- and N-cadherin). Compared with that in the shRNA NC group, the Notch1 shRNA group showed significantly decreased cell proliferation rate and invasiveness; increased apoptotic rate; elevated mRNA expression levels of Bad, Bid and E-cadherin; and reduced mRNA expression levels of Bcl2, N-cadherin and vimentin. The trends for protein expression levels were the same as those for mRNA levels. Notch1 silencing inhibited invasion and promoted apoptosis of BCCs.

Down-regulation of PKM2 decreases FASN expression in bladder cancer cells through AKT/mTOR/SREBP-1c axis

Fatty acid synthase (FASN) catalyzing the terminal steps in the de novo biogenesis of fatty acids is correlated with low survival and high disease recurrence in patients with bladder cancer. Pyruvate kinase M2 (PKM2) regulates the final step of glycolysis levels and provides a growth advantage to tumors. However, it is unclear whether the change of PKM2 has an effect on FASN and what is the mechanisms underlying. Here we describe a novel function of PKM2 in control of lipid metabolism by mediating transcriptional activation of FASN, showing the reduced expression of sterol regulatory element binding protein 1c (SREBP-1c). We first discovered that PKM2 physically interacts with the SREBP-1c using biochemical approaches, and downregulation of PKM2 reduced the expression of SREBP-1c by inactivating the AKT/mTOR signaling pathway, which in turn directly suppressed the transcription of major lipogenic genes FASN to reduce tumor growths. Furthermore, either PKM2 inhibitor-Shikonin or FASN inhibitor-TVB-3166 alone induced a strong antiproliferative and anticolony forming effect in bladder cancer cell line. The combination of both inhibitors exhibits a super synergistic effect on blocking the bladder cancer cells growth. It provides a new target and scientific basis for the treatment of bladder cancer.

Melatonin-mediated downregulation of ZNF746 suppresses bladder tumorigenesis mainly through inhibiting the AKT-MMP-9 signaling pathway

There still lacking effective treatment for bladder cancer. This study investigated whether melatonin (Mel) can suppress the growth and invasion of bladder cancer cells. Male C57B/L6 mice were categorized into control group (ie, subcutaneous injection of HT1197 bladder cancer cell line at the back] and treatment group [subcutaneous HT1197 cells + intraperitoneal Mel (100 mg/kg/d) from day 8 to day 21 after tumor cell injection]. In vitro Mel suppressed cell growth of four bladder cancer cell lines (ie, T24, RT4, HT1197, HT1376), cell migration in HT1197/HT1376, mitochondrial membrane potential (MMP) in T24 and colony formation in RT4 cells as well as arrested the cell cycle at G0 phase and inhibited the mitotic phase of T24 cells (all P < 0.0001). Protein expression of ZNF746 in RT4/T24 cells and protein expression phosphorylated (p)-AKT/MMP-2/MMP-9 in HT1197/HT1376 cells were reduced following Mel treatment (all P < 0.001). Transfection of T24 cells with plasmid-based shRNA (ie, ZNF746-silencing) downregulated the protein expression of MMP-9, cell growth, and invasion and attachment to endothelial cells but upregulated the colony formation (all P < 0.001). Mel suppressed oxidative stress and MMP but upregulated mitochondria mass in ZNF746-silenced T24 cells, whereas these parameters exhibited a similar patter to Mel treatment in ZNF746-silenced T24 cells (all P < 0.0001). In vivo study demonstrated that Mel treatment significantly suppressed cellular expressions of MMP-9/MMP-2, protein expressions of ZNF746/p-AKT, and tumor size (all P < 0.001). Mel treatment suppressed the growth, migration, and invasion of bladder carcinoma cells through downregulating ZNF746-regulated MMP-9/MMP-2 signaling.

The elevated glutaminolysis of bladder cancer and T cells in a simulated tumor microenvironment contributes to the up-regulation of PD-L1 expression by interferon-γ

Background

Metabolic reprogramming occurs in the tumor microenvironment and influences the survival and function of tumor and immune cells. Interferon-γ (IFN-γ) produced by T cells up-regulates PD-L1 expression in tumors. However, reports regarding the relationship between nutrient metabolism and the up-regulation of PD-L1 expression are lacking.

Materials and methods

In this paper, we analyzed the metabolic changes in T cells and bladder cancer cells in a simulated tumor microenvironment to provide evidence regarding their relevance to PD-L1 up-regulation.

Results

The glutaminolysis was increased in both activated T cells and glucose-deprived T cells. IFN-γ production by T cells was decreased in a glucose-free medium and severely decreased when cells were simultaneously deprived of glutamine. Furthermore, the glutaminolysis of the bladder cancer cells under glucose deprivation exhibited a compensatory elevation. The glucose concentration of T cells co-cultured with bladder cancer cells was decreased and T cell proliferation was reduced, but IFN-γ production and glutaminolysis were increased. However, in bladder cancer cells, the elevation in glutaminolysis under co-culture conditions did not compensate for glucose deprivation because the glucose concentration in the culture medium did not significantly differ between the cultures with and without T cells. Our data also show that inhibiting glutamine metabolism in bladder cancer cells could reduce the elevation in PD-L1 expression induced by IFN-γ.

Conclusion

In a simulated tumor microenvironment, elevated glutaminolysis may play an essential role in IFN-γ production by T cells, ultimately improving the high PD-L1 expression, and also directly contributing to producing more PD-L1 in bladder cancer cells.

Flaccidoxide-13-Acetate Extracted from the Soft Coral Cladiella kashmani Reduces Human Bladder Cancer Cell Migration and Invasion through Reducing Activation of the FAK/PI3K/AKT/mTOR Signaling Pathway

Metastasis of cancer is the cause of the majority of cancer deaths. Active compound flaccidoxide-13-acetate, isolated from the soft coral Cladiella kashmani, has been found to exhibit anti-tumor activity. In this study, Boyden chamber analysis, Western blotting and gelatin zymography assays indicated that flaccidoxide-13-acetate exerted inhibitory effects on the migration and invasion of RT4 and T24 human bladder cancer cells. The results demonstrated that flaccidoxide-13-acetate, in a concentration-dependent manner, reduced the levels of matrix metalloproteinase-2 (MMP-2), MMP-9, urokinase-type plasminogen activator receptor (uPAR), focal adhesion kinase (FAK), phosphatidylinositide-3 kinases (PI3K), p-PI3K, AKT, p-AKT, mammalian target of rapamycin (mTOR), p-mTOR, Ras homolog gene family, member A (Rho A), Ras, mitogen-activated protein kinase kinase 7 (MKK7) and mitogen-activated protein kinase kinase kinase 3 (MEKK3), and increased the expressions of tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 in RT4 and T24 cells. This study revealed that flaccidoxide-13-acetate suppressed cell migration and invasion by reducing the expressions of MMP-2 and MMP-9, regulated by the FAK/PI3K/AKT/mTOR pathway. In conclusion, our study was the first to demonstrate that flaccidoxide-13-acetate could be a potent medical agent for use in controlling the migration and invasion of bladder cancer.

Anticancer effect of S-allyl-L-cysteine via induction of apoptosis in human bladder cancer cells

To examine the anticancer effects of S-allyl-L-cysteine (SAC) in human bladder cancer cells and to identify possible molecular mechanisms, bladder cancer cell lines (HTB5, HTB9, JON, UMUC14, T24, and cisplatin resistant-T24R2) were incubated with SAC, and cell proliferation was measured using the Cell Counting Kit-8 assay and clonogenic assay. Cell cycle and apoptosis were evaluated by flow cytometry. Expression levels of apoptosis- and cell cycle-associated proteins were analyzed by western blotting. Proliferation and colony formation in bladder cancer cells was significantly inhibited by SAC treatment in a dose-dependent manner. SAC treatment significantly enhanced apoptosis and promoted a cell cycle arrest in the S phase. SAC also increased the expression of apoptosis-related genes, including caspases, poly (ADP-ribose) polymerase and cytochrome c. SAC had an anticancer effect on bladder cancer cells in vitro, at least partially, through the induction of apoptosis and a cell cycle arrest. SAC is a potential therapeutic agent for the treatment of bladder cancer.

MEK inhibition enhances efficacy of bacillus Calmette-Guérin on bladder cancer cells by reducing release of Toll-like receptor 2-activated antimicrobial peptides

Bacillus Calmette-Guérin (BCG) is one of the standard treatment options for non-muscle-invasive bladder cancer. The details of the biological defense mechanisms against BCG remain unclear. Here, we investigated whether BCG-induced release of antimicrobial peptides (AMPs; e.g., human β-defensin-2, -3, and cathelicidin) is involved with mitogen-activated protein kinase (MAPK) pathways, and investigated the enhanced anticancer effect of BCG through the down-regulation of Toll-like receptors (TLRs) and MAPK pathways in bladder cancer cells. BCG-infected bladder cancer cells produced AMPs as a defense mechanism against BCG, which were reduced by MEK inhibitors by blocking phosphorylation of extracellular signal-regulated kinase (ERK1/2 or MEK) and c-Jun. MEK inhibitors enhanced inhibition of bladder cancer cell growth by decreased binding of c-Jun, p65 and Pol II to the activated protein-1 promoter. Knockdown of TLR2 and TLR4 reduced ERK phosphorylation. Knockdown of TLR 2 decreased release of AMPs, which was similar to the efficacy of MEK inhibitor on BCG-infected cells. BCG-infected bladder cancer cells were more prone to induction of AMP release following TLR2 activation via ERK and c-Jun pathway mediators. In conclusion, our data suggest that the BCG-induced release of AMPs in bladder cancer cells is a promising molecular target for enhancing the immunotherapeutic efficacy of BCG in bladder cancer patients.

Chemotherapeutic potential of quercetin on human bladder cancer cells

In an effort to improve local bladder cancer control, we investigated the cytotoxic and genotoxic effects of quercetin on human bladder cancer T24 cells. The cytotoxic effect of quercetin against T24 cells was examined by MTT test, clonogenic assay as well as DNA damaging effect by comet assay. In addition, the cytotoxic effect of quercetin on the primary culture of papillary urothelial carcinoma (PUC), histopathological stage T1 of low- or high-grade tumours, was investigated. Our analysis demonstrated a high correlation between reduced number of colony and cell viability and an increase in DNA damage of T24 cells incubated with quercetin at doses of 1 and 50 µM during short term incubation (2 h). At all exposure times (24, 48 and 72 h), the efficacy of quercetin, administered at a 10× higher dose compared to T24 cells, was statistically significant (P < 0.05) for the primary culture of PUC. In conclusion, our study suggests that quercetin could inhibit cell proliferation and colony formation of human bladder cancer cells by inducing DNA damage and that quercetin may be an effective chemopreventive and chemotherapeutic agent for papillary urothelial bladder cancer after transurethral resection.

Synergistic effects of cisplatin and proteasome inhibitor bortezomib on human bladder cancer cells

The proteasome inhibitor bortezomib is a promising novel agent in bladder cancer therapy; however, inducible cytoprotective mechanisms may limit its potential efficacy. To date, the cellular and molecular effects of proteasome inhibitors on bladder cancer cells have been poorly characterized. Despite the consistent rate of initial responses, cisplatin treatment typically results in the development of chemoresistance, leading to therapeutic failure. Therefore, the present study aimed to characterize the molecular mechanisms underlying the anti-proliferative effects of cisplatin and bortezomib combination therapy on the human T24 bladder cancer cell line, by analyzing the protein expression levels of apoptotic genes. Cytotoxic effects were measured using a water-soluble tetrazolium salt-1 assay, and the apoptosis-associated molecules were examined using western blot analysis and ELISA. It was observed that combined administration of cisplatin and bortezomib induced upregulation of caspase-3, -8 and -9, B-cell lymphoma-2 (Bcl-2)-like 11 and Bcl-2-interacting killer, but downregulated Bcl-2 and Bcl-extra large protein expression levels in T24 cells in a dose-dependent manner. Furthermore, enhanced protein expression of caspase-8 and -9, in line with the significantly increased caspase-3 activation, was detected when the cells were treated with a combination of cisplatin and bortezomib, compared with that of either agent alone. Bortezomib appeared to synergize with cisplatin to promote apoptosis via the extrinsic and intrinsic apoptotic pathways. Taken together, the results of the current study provide the preclinical framework for additional evaluation of the effects of combining bortezomib with other agents to induce apoptosis in bladder cancer cells.

The Akt inhibitor, perifosine, enhances the sorafenib-induced cytotoxicity against bladder cancer cells

Sorafenib, a tyrosine kinase inhibitor, has been demonstrated to exert anti-tumor effects. However, the molecular mechanisms underlying its effects on bladder cancer remain unknown.

Here, we evaluated the mechanisms responsible for the sorafenib-induced anti-tumor effects on 5637 and T24 bladder cancer cells. We demonstrated that sorafenib reduces cell viability, stimulates lysosome permeabilization and induces apoptosis of bladder cancer cells. These effects are dependent by the activation of cathepsin B released from lysosomes. The sorafenib-increased cathepsin B activity induced the proteolysis of Bid into tBid that stimulates the intrinsic pathway of apoptosis characterized by mitochondrial membrane depolarization, oxygen radical generation and cytochrome c release. Moreover, we found that cathepsin B enzymatic activity, induced by sorafenib, is dependent on its dephosphorylation via PTEN activation and Akt inactivation. Pretreatment with orthovanadate rescued bladder cancer cells from apoptosis. In addition, the Akt inhibitor perifosine increased the sensitivity of bladder cancer cells to sorafenib-induced cytotoxicity.

Overall, our results show that apoptotic cell death induced by sorafenib in bladder cancer cells is dependent on cathepsin B activity and involved PTEN and Akt signaling pathways. The Akt inhibitor perifosine increased the cytotoxic effects of sorafenib in bladder cancer cells.

The importance of 1,2-dithiolane structure in α-lipoic acid for the downregulation of cell surface β1-integrin expression of human bladder cancer cells

Here, we show that cell surface β1-integrin expression, cell adhesion to fibronectin, migration, and invasion were all significantly inhibited by α-lipoic acid. These effects were not observed when cells were treated with dihydrolipoic acid or caprylic acid. These data reveal that the 1,2-dithiolane structure plays an important role in the action of α-lipoic acid.

α-Lipoic acid suppresses migration and invasion via downregulation of cell surface β1-integrin expression in bladder cancer cells

Our previous study showed α-lipoic acid (LA) downregulated cell surface β1-integrin expression of v-H-ras-transformed derivative of rat fibroblast with amelioration of their malignant phenotype. Here, we evaluated the ameliorating effect of LA on the malignant characters in H-ras-transformed bladder cancer cells. H-ras mutated bladder cancer line, T24 cells were incubated with LA to evaluate the inhibitory effect on proliferation, migration, invasion and β1-integrin expression. Fluorescence staining of F-actin and western blotting analyses of the related signaling pathways were also performed. LA inhibited the proliferation of T24 cells. Cell adhesion to collagen IV and fibronectin was strikingly inhibited by LA treatment accompanied by downregulation of cell surface but not whole cell β1-integrin expression. LA clearly inhibited cell migration and invasion of T24 cells, which were mimicked by extracellular signal-regulated kinase (ERK) and Akt pathway inhibition. Actually, LA significantly downregulated the phosphorylated ERK and Akt levels. Moreover, LA downregulated phosphorylated focal adhesion kinase level with disappearance of stress fiber formation. Finally, although LA induced the internalization of cell surface β1-integrin, disruption of the raft did not affect the action of LA. Taken together, LA is a promising agent to improve malignant character of bladder cancer cells through regulation of cellular β1-integrin localization.

Development of targeted therapy for bladder cancer mediated by a double promoter plasmid expressing diphtheria toxin under the control of IGF2-P3 and IGF2-P4 regulatory sequences

BACKGROUND

The human IGF2-P3 and IGF2-P4 promoters are highly active in bladder carcinoma, while existing at a nearly undetectable level in the surrounding normal tissue. A double promoter DTA-expressing vector was created, carrying on a single construct two separate genes expressing diphtheria toxin A-fragment (DTA), from two different regulatory sequences, selected from the cancer-specific promoters IGF2-P3 and IGF2-P4.

METHODS

IGF2-P3 and IGF2-P4 expression was tested in samples of urothelial carcinoma (UC) of the bladder (n=67) by RT-PCR or by ISH. The therapeutic potential of single promoter expression vectors (P3-DTA and P4-DTA) was tested and compared to the double promoter toxin vector P4-DTA-P3-DTA in UC cell lines and in heterotopic and orthotopic animal models for bladder cancer.

RESULTS

Nearly 86% of UC patients highly expressed IGF2-P4 and IGF2-P3, as determined by ISH. The double promoter vector (P4-DTA-P3-DTA) exhibited superior ability to inhibit tumor development by 68% (P=0.004) compared to the single promoter expression vectors, in heterotopic bladder tumors. The average size of the P4-DTA-P3-DTA bladder tumors (in orthotopically treated mice) was 83% smaller (P<0.001) than that of the control group.

CONCLUSIONS

Overall, the double promoter vector exhibited enhanced anti-cancer activity relative to single promoter expression vectors carrying either gene alone. Our findings show that bladder tumors may be successfully treated by intravesical instillation of the double promoter vector P4-DTA-P3-DTA.

Mycobacterium phlei cell wall complex directly induces apoptosis in human bladder cancer cells

Intact mycobacteria and mycobacterial cell wall extracts have been shown to inhibit the growth of human and murine bladder cancer. Their mechanism of action is, however, poorly understood. Mycobacterium phlei mycobacterial cell complex (MCC) is a cell wall preparation that has mycobacterial DNA in the form of short oligonucleotides complexed on the cell wall surface. In this study, we have investigated the possibility that MCC has anti-cancer activity that is mediated by two different mechanisms--a direct effect on cancer cell proliferation and viability and an indirect effect mediated by the production of interleukin 12 (IL-12), a cytokine known to possess anti-cancer activity. We have found that, although MCC is a potent inducer of IL-12 and IL-6 synthesis in monocytes and macrophages either in vitro or in vivo, it is unable to induce the synthesis of either IL-12, IL-6 or granulocyte-macrophage colony-stimulating factor (GM-CSF) by the human transitional bladder cancer cell lines HT-1197 and HT-1376. MCC is not directly cytotoxic towards these cancer cells, but induces apoptosis as determined by nuclear DNA fragmentation and by the release of nuclear mitotic apparatus protein. Mycobacterium phlei DNA associated with MCC is responsible for the induction of apoptosis. Our results indicate that MCC directly effects bladder cancer cells by inhibiting cellular proliferation through the induction of apoptosis, and has the potential for an indirect anti-cancer activity by stimulating cancer-infiltrating monocytes/macrophages to synthesize IL-12.