Drugs EADM 5-Fu NVB DDP 70 (14) 80 (16) 55 (11) 75 (15) 30 (6) 20 (4) 35 (7) 25 (5) 0 0 10 (2) 0 Yu et al. Journal of Experimental & Clinical Cancer Research 2010, 29:107 http://www.jeccr.com/content/29/1/107 Table 5 Sensitivity rate of 20 breast cancer cells to 4 kinds anticancer drugs in 0.1 × PPC Desensitize(%) Sensitive(%) Midrange sensitive (%) Sensitivity rate(%) 30 (6) 20 (4) 45 (9) 25 (5) Page 6 of 7 expression of the BCL-2 protein expression level, in particular the combined detection of the expression of BCL-2 and BAD as well as ER and PR were helpful in the prognosis of breast carcinoma. Chemotherapy is an important treatment means of breast cancer. When we choose chemotherapeutic agents in clinical there still have certain blindness. By using the same chemotherapy, the curative effect of dif- ferent individuals have large difference. If we did not know the sensitivity of chemotherapeutic agents and uti- lized them blindly, there would be a lot of side effects. To avoid the side effects we needed to understand the sensitivity of chemotherapeutic agents before the che- motherapy start, and let the treatment individualization. Therefore, before chemotherapy the drug sensitivity, to forecast it becomes necessary, especially. Most che- motherapeutic agents killed tumor cells through indu- cing apoptosis, thus to investigate the regulatory factor in the procession of apoptosis will provide us a insight to know mechanism of the drug resistance. BCL-2 and the members of this family plays an impor- tant role in regulating the process of cell apoptosis. BCL-2 is the anti-apoptotic gene, its mechanism is not yet clear, and it may affect Ca2 + into cells, thereby reg- ulating cell signal transduction, disturbing the adversed function of free radical and so on [8]. The expression product of BAD can formed heterodimer with the expression product of the anti-apoptotic members of BCL-2 gene family, thereby reversed the function of them. There was clinical research indicating that the expression level of BCL-2 has positive correlation with some factors which to benefit the prognosis of breast cancer such as progesterone receptor and estrogen receptor, and has negative correlation with the Table 6 The relationship between the expression of BCL- 2 in breast cancer cells and the relative inhibition ratio of 4 kinds of anticancer drugs + 30.45 ± 2.52 30.44 ± 1.49 34.72 ± 3.44 24.32 ± 3.29 BCL-2 - 34.87 ± 2.25 34.40 ± 2.34 41.19 ± 2.60 29.87 ± 1.90 t 3.99 t’ = 4.25 4.51 4.30 P 0.001 0.001※ <0.05 <0.05 Drugs EADM 5-Fu NVB DDP ※T’ -test disadvantage ones such as EGFR and the number of metastatic lymph node [9]. In the study of breast disease also found in the procession (normal - simple hyperpla- sia - atypical hyperplasia - carcinoma in situ - invasive breast cancer) the expression of BAD had a decreasing trend [10]. In this study we found that the sensitivity of the breast cancer cells to the 4 drugs were higher in the BCL-2 expression negative ones. Through the rank cor- relation analysis we found that there was a negative cor- relation between the BCL-2 expression and the chemosensitivity in breast cancer, indicated that BCL-2 maybe made the breast cancer cells resistant to che- motherapy drugs through its anti-apoptotic function. BCL-2 possibly became one of the effect prognosis fac- tors to determine the curative effect of the chemother- apy in treatment. In our study the breast cancer cells with BAD expression positive were more sensitivity to EADM and NVB than the negative ones. In the tumour cells which BCL-2(-)BAD(+) the chemosensitivity to the 4 drugs are higher than the BCL-2(+)BAD(+)and BCL-2 Table 7 The relationship between the expression of BAD in breast cancer cells and the relative inhibition ratio of 4 kinds of anticancer drugs + 39.95 ± 2.29 30.33 ± 3.90 38.60 ± 2.67 28.70 ± 2.56 BAD - 28.34 ± 6.67 25.76 ± 4.94 26.79 ± 6.42 26.40 ± 2.44 T T’ = 5.78 1.998 T’ = 5.67 2.044 P <0.05※ 0.061 <0.05※ 0.056 Drugs EADM 5-Fu NVB DDP ※T’ -test Table 8 The relationship between the combined expression of BCL-2 and BAD in breast cancer cells and the relative inhibition ratio of 4 kinds of anticancer drugs Drugs BCL-2(+)BAD (-) EADM 5-Fu NVB DDP (n = 8) 25.93 ± 3.05 24.18 ± 4.18 26.06 ± 7.43 23.01 ± 4.14 BCL-2(+)BAD (+) (n = 5) 33.47 ± 4.65 30.38 ± 4.81 36.62 ± 2.78 26.01 ± 4.73 BCL-2(-)BAD (+) (n = 6) 40.16 ± 5.20 37.86 ± 2.80 42.50 ± 2.63 31.90 ± 6.81 BCL-2(-)BAD (-) (n = 1) 37.72 35.11 38.88 28.52