【Abstract】 Objective To investigate the role of myosin l ight chain (Myl) in myogenesis in vitro. Methods The extraocular muscle, diaphragm and gastrocnemius muscle myoblasts (eMb, dMb and gMb) were isolated and purified from 12 3-week-old C57BL/6 mice by using the enzyme digestion and Preplate technique, and then were subcultivated. The Myl expression in Mb was detected by RT-PCR and Western blot analysis; the Mb prol iferation activity was tested by methylene blue assay, and the myotube formation was observed. After anti-Myl antibody (1, 2, 3, 8, 16 ng/mL) was induced in the Mb culture (experimental group), the abil ity of prol iferation of myoblasts and the myotube formation were identified. Meanwhile, the Mb which was cultured without anti-Myl antibody was indentified as the control group. Results The results of RT-PCR and Western blot analysis showed that Myl1 and Myl4 mRNA and Myl protein were expressed in eMb, dMb and gMb at 24 hours after seeding, and their expression level were lower in eMb than in dMb and gMb (P lt; 0.01), and the latter two did not show any significant difference (P gt; 0.05). Myl2 and Myl3 mRNA was not detected in these three myoblasts. The prol iferation assay showed that the eMb prol iferated faster as compared with dMb and gMb (P lt; 0.01). eMb began to yield myotubes at 40 hours after seeding and dMb and gMb at 16 hours after seeding. At 6 days, the number of myotubes derived from eMb was (137.2 ± 24.5)/ field, which was significantly larger than that of myotubes from dMb [(47.6 ± 15.5) / field ] and gMb [(39.8 ± 5.1) field ] (P lt; 0.01). There was not statistically significant difference between the latter two groups (P gt; 0.05). After the antibody treatment, the absorbency values of the eMb, dMb and gMb in the experimental groups at each antibody concentration point were significantly higher than those in the corresponding control groups (P lt; 0.05), and the dose-dependent way was performed.The numbers of myotubes from dMb at 16 hours were (48.2 ± 7.1)/ well in the experimental group and (23.4 ± 4.9)/ well in the control group, and at 6 days were (40.6 ± 10.2)/ field in the experimental group and (63.1 ± 6.1)/ field in the control group.There was statistically significant difference between the experimental and control groups (P lt; 0.01). Conclusion Myl may play a role in myogenesis through the negative effect on the myoblast prol iferation.
Objective To understand the effect of estradiol in different concentrations on proliferation of diverse mammary primary cells in vitro. Methods The primary cells of cancer tissue, the adjacent tissue to tumors and normal mammary tissue from patiens with breast cancer were obtained using collagenase digesting method. All the tissue samples were cultivated in vitro, and were given estradiol in different concentrations. The effect of estradiol on the proliferation of those primary cells was measured by MTT. Results Estradiol remarkedly promoted the proliferation of primary cells of cancer tissue and peritumor tissue in vitro, whose ER expression were positive. Whereas, the promotion effect of estradiol on the proliferation of normal mammary primary cells was relatively weak, and there was no correlation between the promotion effect with the expression of ER in cancer tissue. Conclusion The risks of occurrence and relapse of breast cancer would increase significantly when the concentration of estradiol is no less than 103 pmol/L in vivo.