The competitive dynamics between tumor cells, a replication-competent virus and an immune response

Replication-competent viruses have been used as an alternative therapeutic approach for cancer treatment. However, new clinical data revealed an innate immune response to virus that may mitigate the effects of treatment. Recently, Wein, Wu and Kirn have established a model which describes the interaction between tumor cells, a replication-competent virus and an immune response (Cancer Research 63 (2003):1317-1324). The purpose of this paper is to extend their model from the viewpoints of mathematics and biology and then prove global existence and uniqueness of solution to this new model, to study the dynamics of this novel therapy for cancers, and to explore a explicit threshold of the intensity of the immune response for controlling the tumor. We also study a time-delayed version of the model. We analytically prove that there exists a critical value tau0 of the time-delay tau such that the system has a periodic solution if tau > tau0. Numerical simulations are given to verify the analytical results. Furthermore, we numerically study the spatio-temporal dynamics of the model. The effects of the diffusivity of the immune response on the tumor growth are also discussed.

Quantitative detection of cytokeratin 20 mRNA expression in bladder carcinoma by real-time reverse transcriptase-polymerase chain reaction

OBJECTIVES

To determine cytokeratin 20 (CK 20) expression in tumor tissue, normal urothelial tissue, bladder washings, and urine from patients with urothelial carcinoma by real-time reverse transcriptase-polymerase chain reaction using the LightCycler Instrument.

METHODS

Urine, bladder washings, tumor, and normal urothelial tissue were obtained from 33 patients with bladder carcinoma. RNA was subsequently extracted. Twenty tissue samples from healthy volunteers were used as controls. Real-time reverse transcriptase-polymerase chain reaction with the LightCycler was performed using fluorescence-labeled CK 20 primers as the target gene and the porphobilinogen deaminase housekeeping gene as the internal standard.

RESULTS

CK 20 mRNA expression was detected in all samples investigated. CK 20 expression in the tissue and urine samples from patients with tumor was significantly increased compared with that in normal urothelial tissue (P = 0.028) or urine from the negative control group (P = 0.012). The average CK 20 expression was 70,140 arbitrary units (AU) in tumor tissue (30,533 AU in urine from patients with tumor) and 8460 AU in normal urothelial tissue (2234 AU in normal urine). A stage-related difference in CK 20 mRNA expression was observed in tumor tissue (P = 0.027) and for tumor grade G1-G2 versus G3 (P = 0.03).

CONCLUSIONS

CK 20 mRNA expression levels in tissue and urine were elevated in patients with urothelial carcinoma compared with the levels in healthy individuals. CK 20 expression was also detectable in normal urine or normal urothelial tissue, but at significantly lower levels than in tumor samples. Fluorescence-labeled quantitative polymerase chain reaction using the LightCycler helped to differentiate between low-level CK 20 expression in normal urothelial tissue and the levels in tumor tissue samples. CK 20 might be an excellent and sensitive marker for tumor monitoring and routine follow-up in patients with transitional cell carcinoma.

Evaluation of co-stimulatory effects of Tamarindus indica L. on MNU-induced colonic cell proliferation

Colonic cell proliferation is the prerequisite for the genesis of cancer. Experimental and epidemiologic evidence indicate dietary factors to be one of the commonest predisposing factors in the development of several types of cancers including large intestine. Here we have investigated the role of the fruit pulp of Tamarindus indica L. (TI), a tropical plant-derived food material, on the proliferating colonic mucosa using Swiss albino mice. Crypt cell proliferation rate (CCPR), on histological basis and [3H]-thymidine incorporation assay were chosen to evaluate the modulating potential of TI per se and in response to a subacute dose of N-nitroso N'-methyl urea (MNU). Descending colonic segment showed greater rate of cell proliferation than the ascending colon and cecum tissues isolated from the group 2 (TI-per se) when compared with group 1 (negative controls). It also revealed a positive correlation with the incorporation studies. Significant increase in the CCPR and radiolabeled precursor incorporation (p <0.001) was observed in MNU-induced+TI fed group of animals (group 4) in all the three segments when compared with control diet fed normal (group 1) as well as MNU-induced (group 3) animals. This study therefore indicates a co-stimulatory effect of TI on MNU-induced colonic cell kinetics.