Proliferative response of human prostate tumour xenografts to surgical trauma and the transurethral resection of the prostate controversy

High-Resolution Ultrasound Allows Percutaneous Initiation and Surveillance of Prostate Cancer in an Orthotopic Murine Model

Introduction: Prostate cancer xenografts should prefer orthotopic growth to subcutaneous tumors as the former more closely mimics the natural tumor environment. However, these models are technically demanding and require an invasive laparotomy. To overcome these problems, we evaluated a minimally invasive approach by performing percutaneous prostate puncture under the control of high-resolution ultrasound imaging. Materials and Methods: Orthotopic tumor cell inoculation was performed in two groups of mice, i.e. in 10 nude mice via ultrasound-guided inoculation and in another 10 nude mice via an open surgical approach. Tumor growth was monitored after 4, 5 and 6 weeks by means of a high-resolution ultrasound system. Results: High-resolution ultrasound allowed exact tumor growth monitoring. After ultrasound-guided inoculation, 8 of 10 animals showed tumor engraftment. The surgical procedure was successful in 9 of 10 animals. Tumor volume was slightly but not significantly greater after surgical tumor induction. Our work demonstrates that tumor cell inoculation via percutaneous puncture of the prostate is feasible, less time-consuming and minimally invasive compared to an open surgical approach. This reduces the animal burden. Conclusion: Although the tumor size and the precision of inoculation is lower compared to the open surgical technique, this novel procedure enables real-time prostate punctures, suggesting the feasibility of other procedures including biopsy and local drug applications.

Early events of hepatic metastasis formation in mice: role of Kupffer and NK-cells in natural and interferon-gamma-stimulated defense

Surgical manipulation of a tumor may result in increased influx of tumor cells into the systemic and portal circulation and give rise to formation of metastases. In addition, major surgery has been reported to cause profound immunosuppression. In an attempt to increase the host-antitumor immune mechanisms following surgery we have studied the effect of preoperative administration of interferon-gamma, related to the antimetastatic effects of Kupffer cells (KC) and natural killer cells (NK-cells) in the early phase of liver metastasis formation. Colon carcinoma cells were injected into the superior mesenteric vein of syngeneic mice and after 17 days metastases were quantified by weight, number, and uptake of [125I]iododeoxyuridine. Unstimulated control mice developed 10.5 surface nodules per liver 17 days following injection of colon carcinoma cells into the superior mesenteric vein of syngeneic mice. This figure was only 2.6 in mice stimulated with a single dose of 1000 IU IFN-gamma 4 h prior to inoculation of tumor cells. Administration of GdCl3, which is reported to deplete and block the function of Kupffer cells, 24 h prior to tumor cell inoculation resulted in a 5-fold tumor mass increase relative to control. Injection of anti-asiolo-GM1 antiserum, which eliminates the hepatic NK-cells, induced a 10-fold increase in tumor mass. These results indicate an important early antimetastatic function of hepatic NK-cells and KC and that presurgical administration of IFN-gamma may be important for eliminating circulating tumor cells and inhibiting development of residual tumors.

Proliferative response of human and animal tumours to surgical wounding of normal tissues: onset, duration and inhibition

Acceleration of secondary tumour growth and metastases following excision of a primary tumour has been attributed to the consequent removal of primary tumour-generated inhibitory factors. However, our studies have shown that surgical wounding of normal tissues significantly stimulated the growth of malignant tissues without the concomitant presence or excision of a tumour mass. A humoral stimulating component was indicated by the proliferative response of tumours and metastases distant from the surgical wound. All 16 human and murine tumours, of nine different histologies, showed a measurable acceleration of growth when implanted in surgically treated animals, suggesting that the ability of malignant tissue to respond to surgical wounding of normal tissue was not histologically or species specific. The proliferative surge of malignant tissues was detectable soon after wounding and had a duration of 2-3 days. The surgical wound as the source of the tumour-stimulating factor(s) was affirmed by the significant inhibition of tumour proliferative responses when a somatostatin analogue was applied topically to the surgical wound within 1 h of wounding, and/or during the critical tumour-stimulatory period of 1-2 days after wounding. A potential therapeutic window for reducing a risk factor that may be inadvertently imposed upon every surgical/oncology patient is indicated.