A small mammal model of tumour implantation, dissemination and growth factor expression after partial hepatectomy

BACKGROUND

Surgical resection remains the most effective therapy for metastatic colorectal cancer confined to the liver, although the extrahepatic recurrence rate is high.

AIM OF THE STUDY

To develop a mammal model in order to investigate by which mechanisms liver surgery affects distant tumour recurrence.

METHODS

In this animal study the effect of partial hepatectomy (phX) on the development of tumour noduli in the lungs was evaluated. CC531 rat colon carcinoma cells were inoculated i.v. 24h before, during or 24h after surgery. Rat serum was obtained at different time-points after phX and added to in vitro CC531 cell cultures. Finally, phX was compared with an ileum resection (ilX).

RESULTS

phX leads to increased tumour noduli in the lungs, compared to Sham operation (p=0.002), but only when performed directly before the injection of tumour cells and not when performed 24h before or after the inoculation. Comparable results were obtained for ilX. No growth stimulation of tumour cells after incubation with rat serum, obtained at different time-points after phX, could be detected in vitro.

CONCLUSION

Not only phX, but also surgery, in general promotes distant tumour recurrence exerting the effect during the early phase of tumour cell adhesion and not during tumour outgrowth.

The role of superoxide anions in the development of distant tumour recurrence

We hypothesise that reactive oxygen species (ROS) released from activated polymorphonuclear leucocytes during surgery play a crucial role in enhanced tumour recurrence seen after surgery. Therefore, the effect of ROS on adhesion of tumour cells to microvascular endothelium in a reproducible human in vitro model was studied. Preincubation of microvascular endothelial cells with the superoxide anion producing xanthine–xanthine oxidase complex significantly increased adhesion of the human colon carcinoma cells HT29 (167% vs control, P<0.01), Caco2 (164% vs control, P<0.01) and of the pancreas carcinoma cells PanC1 (180% vs control, P<0.01). Addition of the antioxidant enzymes superoxide dismutase or catalase significantly decreased tumour cell adhesion (P<0.01). Exposure of endothelial cells to superoxide anions increased the apoptotic rate to 7.9 times the normal rate. Additionally, exposure increased expression of the endothelial adhesion molecules E-Selectin, ICAM-1, and VCAM-1 of maximally 170% vs control (P<0.01). In conclusion, this study shows that superoxide anions promote the adherence of tumour cells to the microvasculature by inducing endothelial apoptosis that subsequently induces the expression of various adhesion molecules for tumour cells. This indicates that by tackling the production of ROS preventing tumour recurrence at distant sites might be feasible.

Metastasectomy, a feasible treatment in selected cases with gynecologic malignancy

We present the course of six gynecological patients who underwent surgical intervention because of a solitary metastasis. After a considerable follow-up period five patients are alive without evidence of disease and with a good quality of life. Metastasectomy should play a role in the management of gynecologic malignancies.

Efficacy of liposomal amphotericin B with prolonged circulation in blood in treatment of severe pulmonary aspergillosis in leukopenic rats

The therapeutic efficacy of long-circulating polyethylene glycol-coated liposomal amphotericin B (AMB) (PEG-AMB-LIP) was compared with that of AMB desoxycholate (Fungizone) in a model of severe invasive pulmonary aspergillosis in persistently leukopenic rats as well as in temporarily leukopenic rats. PEG-AMB-LIP treatment (intravenous administration) consisted of a single, or double (every 72 h), or triple (every 72 h) dose of 10 mg of AMB/kg of body weight, a double dose (every 72 h) of 14 mg of AMB/kg, or a 5-day treatment (every 24 h) with 6 mg/kg/dose. AMB desoxycholate was administered for 10 consecutive days at 1 mg of AMB/kg/dose. Treatment was started 30 h after fungal inoculation, at which time mycelial growth was firmly established. Both persistently and temporarily leukopenic rats died between 4 and 9 days after Aspergillus fumigatus inoculation when they were left untreated or after treatment with a placebo. In persistently leukopenic rats, a single dose of PEG-AMB-LIP (10 mg/kg) was as effective as the 10-day treatment with AMB desoxycholate (at 1 mg/kg/dose) in significantly prolonging the survival of rats infected with A. fumigatus and in reducing the dissemination of A. fumigatus to the liver. Prolongation of PEG-AMB-LIP treatment (double or triple dose or 5-day treatment) did not further improve efficacy. For temporarily leukopenic rats no major advances in efficacy were achieved compared to those for persistently leukopenic rats, probably because the leukocyte numbers in blood were restored too late in the course of infection.