sequence- dependent manner in vivo. a LCC6 cells were injected into the mammary fat pad of female athymic mice to form xenograft tumors. Treatment was performed when mice tumors reached a volume of * 500 mm 3 . Three mice were pre-treated with OSI 30 mg/kg for 4 h and then treated with 00 l g of IGF-I for 40 min. Two mice were treated with 00 l g of IGF-I for 40 min. One mouse was control. Then, mice were killed, and tumor penlac samples were frozen in liquid nitrogen and homogenized in TNESV buffer. A total of 00 l g of tumor extract were immunoblotted for IGFR, InsR, phospho-Akt, and Akt. b Female athymic mice were injected with LCC6 cells in the mammary fat pads to form xenograft tumors.

At day 7, mice were treated with vehicle control, DOX (3 mg/kg/week each, i.p.), OSI-906 ( OSI ) (50 mg/mouse/week, p.o.), DOX ? OSI, DOX 4 h followed by OSI or OSI 4 h Bleomycin followed by DOX four times at a 7 day interval. The arrows indicate the days of drug administration. Tumors were measured every 3 days. c Tumor volumes of mice from different treatment groups on the day of killing. Tumor growth curves were analyzed as described in the Materials and methods section. Specifically, control versus DOX: P parthenolide 20554-84-1 0.073; control versus OSI: P = 0.0; DOX versus DOX ? OSI: P = 0.006; DOX versus DOX followed by OSI: P = 0.067; DOX versus OSI followed by DOX: P = 0.473 4 h followed by OSI-906; (6) OSI-906 treatment followed by DOX 4 h later. All treatments were given once weekly. As shown in Fig. 5 b, c, both DOX and OSI-906 alone significantly inhibited tumor growth compared to control. Simultaneous OSI-906 and DOX treatment further enhanced the anti-tumor effect of DOX (DOX vs. DOX ? OSI: P = 0.006). DOX followed by OSI-906 also enhanced the effect of DOX, but to a lesser extent (DOX vs. DOX followed by OSI: P = 0.067).

In contrast, OSI-906 followed by DOX was not statistically different than DOX alone as measured by tumor volumes (Fig. 5 c). Therefore, our result indicated that OSI-906 enhanced the cytotoxicity of DOX when given once a week. Our data suggest that buy parthenolide OSI-906 given 4 h prior to DOX was an inferior sequence. Simultaneous OSI-906 and DOX treat- ment appeared to be the optimal schedule to inhibit tumor growth. Moreover, a single dose of OSI-906 could enhance the effects of DOX. Discussion stimulated the phosphorylation of Akt, and pre-treatment of OSI-906 abolished the IGF-I induced Akt phosphorylation. The total levels of IGFR and InsR remained unaffected. These results suggest that OSI-906 can effectively block IGF-I signaling in vivo. Since PQIP enhanced the cytotoxicity of DOX in vitro, we sought to determine whether OSI-906 sequencing was relevant in vivo using xenograft models. When LCC6 xe- nografts reached a palpable size, mice were treated on the following schedules:

vehicle control; () DOX; (3) OSI- 906; (4) DOX and OSI-906 simultaneously; (5) DOX for The importance of the IGFR pathways in breast cancer is already well recognized based on numerous reports. Recently, several lines of evidence support the important function of InsR in cancer cell proliferation and metastasis , 6 – 8 . Furthermore, IGFR and InsR play compen- satory roles in regulating cancer cells 9 , 30 . Therefore, TKIs, such as PQIP/OSI-906, may have better anti-tumor effects than monoclonal antibodies targeting IGFR alone. The effect of combining anti-IGFR/InsR TKIs with che- motherapy drugs has not been characterized in the past. Our study have shown that co-administration of TKIs with 3 7 Breast Cancer Res Treat DOX has the best anti-tumor effects, providing  cognitive impairment significant implications for the clinical development of this strategy. Our study also showed that PQIP can induce autophagy, but not apoptosis. Autophagy is activated to maintain cel- lular homeostasis under conditions of metabolic stress or nutrient deprivation 3 . Cells that undergo autophagy stop proliferation and in some instances may undergo senescence 3 . Whether cell death is induced by or is associated with