Objective: To investigate the therapeutic effect of nano-sized liposomal adriamycin (NLADR) administered by various routes on rabbits bearing advanced breast tumors.
Methods: NLADR with a mean diameter of 120 nm was prepared by pH gradient-driven drug encapsulation method. VX(2) tumor mass suspension was injected into the breast tissues of 50 female New Zealand White rabbits. Six weeks after the inoculation 38 surviving tumor-bearing rabbits were randomly divided into 5 groups: group A (control group), receiving a sham treatment; group B, receiving subcutaneous injection of NLADR with a dose of 1 mg/kg into the areas adjacent to the implanted tumor; group C, receiving intravenous injection of NLADR with a dose of 1 mg/kg; group D, receiving NLADR with a dose of 1 mg/kg administered by subcutaneous injection combined with intravenous injection with half of the whole dose for both routes; and group E, receiving intravenous injection of free adriamycin (FADR). The treatment was repeated every 48 hours. The rabbits were killed 48 hours after the third treatment. The breast tumors, axillary lymph nodes, and all of the metastatic tumors anatomically detected in distant organs were collected. The sizes of tumors and axillary nodes before and after treatment were measured. Necrosis of tumor tissue was assessed pathologically. The mRNA expression of proliferating cell nuclear antigen (PCNA) was determined using RT-PCR. Apoptosis was identified and quantified as apoptosis index (AI) using TUNEL method.
Results: The average growth rate of tumor was the highest in group A (1.58) and the lowest in group C (1.33). The average growth rate of axillary lymph nodes was the highest in group A (3.70), significantly higher than in any other groups (all P = 0.00); and was the lowest in group B, significantly lower than groups A, C, and E (all P < 0.01), however without a significant difference between groups B and D (P = 0.148). The PCNA mRNA expression level of the implanted tumor in groups C was the lowest, significant lowest then those in group A and B (both P < 0.01). The sequence of PCNA mRNA in the axillary lymph nodes was group B < group D < group C < group E < group A with significant differences between group B and groups A, C, and E. The sequence of PCNA mRNA in the mediastinal lymph nodes was group B < Group E < group D < group C < group A. The PCNA mRNA expression level was the lowest in group D, significantly lower than that in group A (P = 0.011). Necrosis of implanted tumor, metastatic foci in lung and liver, and lymph nodes was obvious in groups C, D, and E. Necrosis of implanted tumor and metastatic foci in lung and liver was significantly obvious in group C than in group D (P = 0.000 and P = 0.022). Necrosis of the implanted tumor was significantly more obvious in group C than in group F (P = 0.033). Necrosis of axillary lymph nodes was significantly more obvious in group than in groups C and E (P = 0.000 and P = 0.000). The values of AI of the implanted tumor in groups C and D were 16.74% and 18.04%, both significantly higher than those in group E (P = 0.02 and P = 0.04), and those of group E were significantly higher than those in groups A and B (both P < 0.01). The AI value of the axillary lymph nodes was 21.73%, significantly than those in groups A, C, and E (all P < 0.01). The average AI values of the metastatic foci were 16.52%, 15.77%, and 14.50%, all significantly higher than that in group B (all P < 0.01), and that of group B was significantly higher than that in group A (P = 0.039).
Conclusion: NLADR, especially intravenous administration combined with subcutaneous administration, is effective in treatment of advanced breast carcinoma with lymphatic and distant metastases.