Cooperative antitumor effect of endothelial-monocyte activating polypeptide II and flutamide on human prostate cancer xenografts

Recombinant cytokine-like endothelial monocyte-activating polypeptide II (EMAP II) and antiandrogen flutamide target different mechanisms of growth of androgen-dependent prostate cancer (PC). The aim of this study was to clarify whether combined treatment with EMAP II and flutamide is more effective than monotherapy with regard to retardation of PC progression.

MATERIALS AND METHODS

Antitumor effects of EMAP II (10 µg/kg b.w./d, s.c., 3d), or flutamide (10 mg/kg b.w./d, per os, 3d), or their combination were studied in CBA male mice bearing human androgen-dependent PC xenografts for 7 days. Androgen-dependent phenotype of the tumors was verified in preliminary castrated mice. The xenografts were weighed and underwent a histopathologic examination. The results were compared with those of non-treated mice.

RESULTS

EMAP II and flutamide used separately inhibited growth of the xenografts by 74% and 53% respectively. Both drugs caused destructive changes in malignant epithelial cells along with leukocyte infiltration of the tumor. Combined treatment inhibited tumor growth by 85%, and was more effective than monotherapy with regard to morphological changes.

CONCLUSIONS

This study demonstrates cooperative inhibitory effect of EMAP II and flutamide on growth and morphology of human PC xenografts that could represent a new modality of palliative treatment of this disease.

Antitumor effect of endothelial monocyte-activating polypeptide-II on human prostate adenocarcinoma in mouse xenograft model

Endothelial monocyte-activating polypeptide-II (EMAP-II) is a novel proinflammatory cytokine with anti-angiogenic properties. The aim of this work was to evaluate in vivo antitumor activity of EMAP-II in growing human prostate adenocarcinoma xenograft mouse model.

MATERIALS AND METHODS

Recombinant human EMAP-II was expressed in Escherichia coli and purified after cleavage with enterokinase (EMAP-II e). EMAP-II preparations were injected to CBA mice bearing subrenal capsule xenografts of human prostate adenocarcinoma. After 3-days treatment, the xenografts were isolated and weighed, then the transplants exposed to EMAP II e (100 or 200 microg/kg b. w.) were examined histologically.

RESULTS

EMAP-II administered daily at a dose of 100 or 200 microg/kg b. w. caused striking retardation of local tumor progression as compared to the controls. Low dose (10 microg/kg) was effective in some cases.

CONCLUSION

EMAP II exhibits significant antitumor activity in vivo in human prostate adenocarcinoma xenografts in mouse model.