| In recent years, several series of epidemiologic, clinical and experimental evidences have been demonstrated that estrogen hormones may be involved in malignant colorectal tumors. Most action of estrogen and antiestrogen appears to be exerted via the estrogen receptors (ERs) on target cells. In 1996,a second type of ER had been described. The traditional ER, which was believed to be the only ER, is now called ERa. The newly discovered ER is called ERβ,which has been reported to be highly expressed in normal colon mucosa and colorectal cancer according to several studies. The property of ERβ is still not clear yet.Part I The expression of ERs in colon cancer cell line LoVo and theinhibitory effect of tamoxifen[Objective] To evaluate the effect of tamoxifen on growth and apoptosis of human colon cancer cell line LoVo and the expression of ERs. [Methods] The expression of ERs was determined by Western blot method. Growth of the cells was detected by using acid phosphoesterase test. Apoptosis of the cells was measured by using TUNEL method and flow cytometer, as well as the change of cell-cyclephases.[Results] The expression of ERJ3 could be detected in LoVo cells, while the expression of ERa could not. LoVo cells were treated with TAM ranged from 10~4 to 10~9M. The OD numbers of LoVo after 48 hours were 0.091 ±0.0318,0.165 ±0.1087,0.3 ±0.0879,0.413 ± 0.0295,0.407 ± 0.0231,0.436±0.0158 respectively and 0.442±0.0478 in control group. The inhibitory effect of TAM was presented in ranged from 10"4 to 10~6M(p<0.01). LoVo cells were also treated with 170-E2 ranged from 10"5 to 10"9M. The OD numbers of LoVo cells after 48 hours were 0.535 ± 0.0488,0.54 ± 0.0549,0.544 ± 0.0545,0.560 ± 0.0989,0.588 ± 0.0574 respectively, while, 0.597 ±0.0621 in control group. There was no difference between 170-E2 and control group(p>0.05). Treated with TAM of the concentration of 10~4 and 10"5M, it was measured that apoptosis was increased in cell apoptotic percentage up to 33.26% and 45.87% respectively by flow cytometer. But treated with TAM of the 10 M concentration, it was no significance difference of apoptotic rate in comparison with control group. TUNEL method had showed also the same result.[Conclusions] (1) ER0 is expressed in LoVo cells, nor ERa. (2) TAM showed dose dependant growth inhibition on LoVo cells and induces apoptosis in vitro.Part II The influence of TAM in nude mice haboured colon cancer [Objective] To observe the influence of TAM in nude mice haboured colon cancer.[Methods] Twelve male nude mice were randomly divided to two groups: group TAM and controls. In TAM group 1X105 LoVo cells were implanted subcutaneously(axilla). After tumor nodules reached 150-250mm3 in size, mice had been fed with TAM for 2 weeks. The dose of TAM was 6mg/kg ? d weight. TAM was administrated orally 3 times a day. The rate of tumor inhibition was measured after two weeks. The level of apoptosis was measured by flow cytometer as well. [Result] The rates of tumor inhibition of group TAM was 33.5%. The level of apoptosis was 23.49% in average, while the control was 2.40%. [Conclusions] TAM inhibited the growth of tumor and induced apoptosis in vitro.Part HI The effect of TAM on survivin[Objective]To compare the expression level of survivin in human colon cancer cell line LoVo before and after treatment with TAM and 5-FU. [Methods] Human colon cancer cell line LoVo was treated with TAM and 5-FU and control group was established as well. Cells were cultured after treatment in 24 and 48 hours. The expression of survivin was determined by SDS-polyacrylamide gel electrophoresis and immunoblotting technique.[Result] When LoVo cells were treated with TAM, the expression of survivin was decreased. The expression level of survivin carried no difference between 5-FU and control.[Conclusions] The mechanism of apoptosis induced by TAM is due to inhibition of survivin expression.Part IV The expression of ER{3 in human colon normal mucosa,adenoma and adenocacinoma[Objective] To study the expression of ER{3 in human colon normal mucosa, adenoma and adenocacinoma.[Methods] The study was performed on tissue sections of normal colon mucosa, adenoma and adenocacinoma from 34 men and 34 women who were treated in HuaShan Hospital. The mean age of the patients was 64.The expression of ERs was evaluated by immunohistochemistry. [Results]The expression of ER(3 in human colon normal mucosa, adenoma and adenocacinoma was 26.7%(4/15),41.2%(7/17) and 72.2%(26/36) respectively. It was difference between the expression of ERJ3in normal mucosa and cancer. The expression of ERJ3 had no relationship with sex, the cancer differentation and pathologic staging in human colorectal cancer tissues. In normol tissues, immunoreactivity is different from cancer tissues. [Conclusions] ERp is highly expressed in colorectal cancer tissue. |
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