Determination of Interferon-alpha Receptors in Urothelial Cancer and in Normal Urothelium

Down-regulation of type I interferon receptor sensitizes bladder cancer cells to vesicular stomatitis virus-induced cell death

The intrinsic oncolytic specificity of vesicular stomatitis virus (VSV) is currently being exploited to develop alternative therapeutic strategies for bladder cancer and other cancers. Previously we reported that oncolytic VSV is a potent agent for intravesical treatment of high risk bladder cancer. We observed that VSV preferentially targeted bladder cancer cells resistant to type I interferon (IFN) treatment. The goal of the current study was to further elucidate the nature of the molecular defect of IFN signaling by which bladder cancer cells become susceptible to VSV infection. Using a tissue microarray composed of human bladder cancer cores, we observed that expression of type I IFN receptor (IFNAR) was decreased relative to normal bladder tissue. Advanced bladder cancers had even lower expression of IFNAR. We found that bladder cancer cells susceptible to VSV-induced lysis had low expression of IFNAR as well. We hypothesized that down-regulation of IFNAR in bladder cancer cells may be a molecular mechanism responsible for resistance to type I IFN treatment and sensitivity to VSV oncolysis. SiRNA knockdown of IFNAR indeed facilitated replication of VSV in cells previously resistant to VSV treatment. Blocking IFNAR with a neutralizing antibody showed a similar effect. Hence down-regulation of IFNAR in bladder cancer may be one of the primary molecular mechanisms for clinical IFN resistance. However, this also facilitates VSV replication and oncolysis in high risk bladder cancers and provides a basis for selecting bladder cancer patients for IFN or oncolytic VSV therapy in future clinical trials.

Chemiluminescent imaging analysis of interferon alpha in serum samples

Enzyme-linked immunosorbent assay (ELISA), horseradish peroxidase (HRP)-catalyzed fluorescent reaction, and oxalate chemiluminescence imaging analysis have been combined to develop a sensitive, simple, and rapid method for analysis of interferon alpha (alpha-IFN) in human serum samples. A typical "sandwich type" immunoassay was used. Reaction of o-phenylenediamine (OPD) with hydrogen peroxide (H(2)O(2)), catalyzed by HRP, produced 2,3-diaminophenazine (PDA), which was detected by chemiluminescence imaging analysis with the bis(2,4,6-trichlorophenyl)oxalate (TCPO)-H(2)O(2)-glyoxaline-PDA chemiluminescent system. The TCPO chemiluminescent imaging system is more sensitive and the chemiluminescence quantum yield is at least five times higher than for the luminol-H(2)O(2)-HRP-PIP (p-iodophenol) chemiluminescent imaging system. The results showed there was a very good linear correlation between response and amount of alpha-IFN in the range 1.3-156.0 pg mL(-1) (R = 0.9991) and the detection limit was 0.8 pg mL(-1) (S/N=3). The relative standard deviation (n = 9) was 4.7%. The proposed method has been used for successful analysis of the amount of alpha-IFN in human serum. The results obtained compared well with those obtained by conventional colorimetric ELISA and luminol chemiluminescent ELISA.

Changes in end products of nitric oxide in urine and induction of nitric oxide synthase expression in urinary bladder during intravesical instillations of IFN-alpha2b

Interferon-alpha2b (IFN-alpha2b) is being used intravesically for preventing recurrence and progression of superficial transitional cell carcinoma of the bladder. However, its mechanism of action when instilled intravesically is not yet elucidated. We monitored end products of nitric oxide (NO) in urine in 12 bladder cancer patients undergoing intravesical instillations of IFN-alpha2b. Urine end products of NO levels rose gradually after each instillation, reaching a peak value after the third instillation. Although the patients continued their treatment for 5 more weeks, no further alteration was observed. Inducible nitric oxide synthase (iNOS) expression was immunohistochemically evaluated in urinary bladder biopsy specimens before and after IFN-alpha2b instillations. It was shown that IFN-alpha2b induced urothelial iNOS expression, with subsequent oxidative stress. The peroxynitrite (ONOO-) formed from the combination of NO with superoxide (O2-) provides important clues in the role of ONOO- as a causative factor in the antineoplastic action of IFN-alpha2b.

Two components of a secreted cell number-counting factor bind to cells and have opposing effects on cAMP signal transduction in Dictyostelium

A secreted 450-kDa complex of proteins called counting factor (CF) is part of a negative feedback loop that regulates the size of the groups formed by developing Dictyostelium cells. Two components of CF are countin and CF50. Both recombinant countin and recombinant CF50 decrease group size in Dictyostelium. countin- cells have a decreased cAMP-stimulated cAMP pulse, whereas recombinant countin potentiates the cAMP pulse. We find that CF50 cells have an increased cAMP pulse, whereas recombinant CF50 decreases the cAMP pulse, suggesting that countin and CF50 have opposite effects on cAMP signal transduction. In addition, countin and CF50 have opposite effects on cAMP-stimulated Erk2 activation. However, like recombinant countin, recombinant CF50 increases cell motility. We previously found that cells bind recombinant countin with a Hill coefficient of approximately 2, a KH of 60 pm, and approximately 53 sites/cell. We find here that cells also bind 125I-recombinant CF50, with a Hill coefficient of approximately 2, a KH of approximately 15 ng/ml (490 pm), and approximately 56 sites/cell. Countin and CF50 require each other's presence to affect group size, but the presence of countin is not necessary for CF50 to bind to cells, and CF50 is not necessary for countin to bind to cells. Our working hypothesis is that a signal transduction pathway activated by countin binding to cells modulates a signal transduction pathway activated by CF50 binding to cells and vice versa and that these two pathways can be distinguished by their effects on cAMP signal transduction.

Comparison of 125I-interferon-alpha binding to peripheral blood cells from African-Americans and Caucasians with hepatitis C

Interferon-alpha (IFN-alpha) is the major treatment for chronic hepatitis C virus (HCV) infection. Drug resistance is problematic, particularly among African-Americans who typically show poorer clinical outcomes than Caucasians. The reasons for ethnic variation in IFN-alpha sensitivity are not clear. We speculated that African-American insensitivity to IFN-alpha may be mediated by reduced density of the IFN-alpha receptor (IFN-alphaR) or reduced internalization of the IFN-alpha/IFN-alphaR complex. This speculation was evaluated by comparing binding, uptake and release of 125iodine-labelled IFN-alpha (125I-IFN-alpha) to peripheral blood cells from African-Americans and Caucasians with HCV infection and ethnically matched healthy volunteers. Under various in vitro conditions, binding of 125IFN-alpha to surface receptors was equivalent (P = ns) between African-Americans and Caucasians with HCV infection as well as healthy volunteers (P = ns). Similarly, internalization and release of the 125I-IFN-alpha/IFN-alphaR complex was equivalent (P = ns) between African-Americans and Caucasians with HCV infection and healthy volunteers (P = ns). In addition, ethnicity did not influence (P = ns) IFN-alpha suppression of phytohaemagluttinen induced proliferation. However, IFN-alpha therapy of the same patients showed that African-Americans had lower response rates than Caucasians (14%vs 54%, P < 0.0001). In summary, IFN-alpha resistance among African-Americans is not mediated by intrinsic differences in IFN-alpha receptor density or internalization.

Cells respond to and bind countin, a component of a multisubunit cell number counting factor

In Dictyostelium discoideum counting factor (CF), a secreted approximately 450-kDa complex of polypeptides, inhibits group and fruiting body size. When the gene encoding countin (a component of CF) was disrupted, cells formed large groups. We find that recombinant countin causes developing cells to form small groups, with an EC(50) of approximately 3 ng/ml, and affects cAMP signal transduction in the same manner as semipurified CF. Recombinant countin increases cell motility, decreases cell-cell adhesion, and regulates gene expression in a manner similar to the effect of CF. However, countin does not decrease adhesion or group size to the extent that semipurified CF does. A 1-min exposure of developing cells to countin causes an increase in F-actin polymerization and myosin phosphorylation and a decrease in myosin polymerization, suggesting that countin activates a rapid signal transduction pathway. (125)I-Labeled countin has countin bioactivity, and binding experiments suggest that vegetative and developing cells have approximately 53 cell-surface sites that bind countin with a K(D) of approximately 1.5 ng/ml or 60 pm. We hypothesize that countin regulates cell development through the same pathway as CF and that other proteins within the complex may modify the activity of countin and/or have independent size-regulating activities.

Efficacy of escalating doses of intravesical interferon alpha-2b in reducing recurrence rate and progression in superficial transitional cell carcinoma

OBJECTIVE

To compare the efficacy of three different doses of intravesical interferon alpha-2b (IFN alpha-2b) in reducing recurrence and progression rates in superficial grade II, transitional cell carcinoma (TCC).

PATIENTS AND METHODS

Eighty-nine patients with primary or recurrent TCC stage Ta/T1, grade II, were randomly allocated into four groups after transurethral resection (TUR) of the tumour. Group A (20 patients) received no further treatment, serving as the control group; group B (22 patients) received 40 MU of IFN alpha-2b, group C (24 patients) 60 MU and group D (23 patients) 80 MU. The instillations started within 48-72 h after TUR and were performed weekly for 2 months, bimonthly for the next 4 months and thereafter monthly for 6 months. The patients were followed for 36 months. The four groups were compared for the number of recurrences (simple recurrence rate), progression in stage, disease-free interval and recurrence rate per 100 patient-months.

RESULTS

During the follow-up, 33 patients had recurrence (13, eight, seven and five in groups A to D, respectively). The simple recurrence rate was 65% for group A, compared with 36% (P = 0.06), 29% (P < 0.05) and 22% (P < 0.01) for groups B, C and D, respectively. The differences in simple recurrence rates between the groups treated with IFN alpha-2b were not statistically significant. Eleven patients experienced progression in stage, with six, there, one and one in groups A to D, respectively. The differences were statistically significant only between groups A and C (P < 0.05) and groups A and D (P < 0.05). The disease-free interval was 15 months for group A, compared with 21.4 (P < 0.05), 26.1 (P < 0.001) and 30 months (P < 0.001) for groups C to D, respectively. The disease-free intervals of the groups treated with IFN alpha-2b were significantly different between all patients in groups B and D (P < 0.01) and only for those with stage T1 between groups C and D (P < 0.01). Finally the recurrence rate per 100 patient-months was 2.91, 1.19, 0.88 and 0.63 for groups A to D, respectively (all P < 0.001). The results were always in favour of the patients treated with the high dose, the only exception being the difference between groups C and D (P = 0.026). No side-effects of the drug were noted, nor was any adverse reaction reported from any patient.

CONCLUSION

These results show a significant advantage for adjuvant intravesical IFN alpha-2b treatment over TUR alone for the 36 months of follow up and indicate that IFN alpha-2b can modify the clinical course of superficial TCC at least in the short term. The appropriate dose was apparently 80 MU, for although 40 MU was better than TUR alone, it was less effective than 60 MU and 80 MU; the 80 MU dose was slightly better than 60 MU and thus this regimen is recommended.

Superficial bladder cancer: the role of interferon-alpha

PURPOSE

We evaluate the clinical experience with recombinant interferon-alpha in superficial transitional cell carcinoma and discuss the most rational use of recombinant interferon-alpha in the context of current treatment options.

MATERIALS AND METHODS

The available data were reviewed and discussed at a consensus conference in August 1996. The conclusions and recommendations are those of the authors based on the consensus reached at that meeting.

RESULTS

While bacillus Calmette-Guerin (BCG) is recognized as the most efficacious intravesical agent in the prophylaxis and treatment of superficial transitional cell carcinoma, it is associated with significant toxicities and a 20 to 40% relapse rate. Interferons, particularly recombinant interferon-alpha, have demonstrated efficacy against primary and recurrent papillary transitional cell carcinoma and carcinoma in situ with minimal toxicity, although the response and relapse rates are inferior to BCG. Intravesical recombinant interferon-alpha therapy has also produced responses in patients who failed to respond or were refractory to BCG or chemotherapy.

CONCLUSIONS

The clinical experience suggests that recombinant interferon-alpha has an important role in the treatment of superficial transitional cell carcinoma, particularly as second line therapy following failure of BCG or chemotherapy, and it may have synergistic effects when combined with chemotherapy or BCG. We propose a prospective randomized study comparing the efficacy of recombinant interferon-alpha, BCG and BCG plus recombinant interferon-alpha as maintenance following complete response to primary BCG therapy. The proposed study would also investigate the efficacy of BCG plus recombinant interferon-alpha as second line therapy following BCG failure. This study will be important to determine the most effective strategy to integrate recombinant interferon-alpha into current treatment options for superficial bladder cancer.