We investigated the role of the transcriptional mediator subunit 23 (MED23) in everolimus drug resistance, invasion and metastasis during breast cancer treatment and its molecular mechanism. We also evaluated the endocrinotherapy and prevention method for breast cancer. Breast cancer cell strains were established that can continuously express MED23, as well as inducible MED23-shRNA expression plasmids. The inductive agent, doxycycline (Dox), was added to the water for long-term silencing of MED23 in intratumoral cells. We conducted experiments on the role of MED23 in the regulation of invasion and metastasis of breast cancer using cell culture, western blotting, MTT proliferation experiment, fluorescent quantitative PCR and chromatin immunoprecipitation (ChIP). The silencing of MED23 significantly inhibited cellular growth and proliferation as well as soft agar cloning. Silencing of MED23 strengthened the sensitivity of the everolimus-resistant breast cancer cell strains BT474 and MCF-7/ADM cells to everolimus medication. The silencing of MED23, in combination with everolimus, inhibits the cell cycle progress of breast cancer cells. ChIP indicated that the mutual regulation of HER2 and MED23 also participates in the formation of the everolimus drug resistance mechanism. Therefore, MED23 plays an important role in everolimus drug resistance, invasion, and metastasis of breast cancer. As a potential molecular therapeutic target of breast cancer, MED23 overcomes drug resistance in clinical endocrinotherapy and controls the distal relapse and metastasis in breast cancer by the targeted silencing of MED23.

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Objective. To investigate the application of carbon nanoparticles in lymph node dissection and parathyroid gland protection during thyroid cancer surgery. Subjects and Methods. Retrospective analysis was performed on 282 cases of thyroid cancer surgery in our hospital from 2018 to 2019. All patients underwent total thyroidectomy and cervical central lymph node dissection. Nanocarbon was not used in the control group, but was used in the experimental group. The general situation of the patients, the number of postoperative lymph nodes and the number of metastasis were collected, and the differences between serum parathyroid hormone and blood calcium were compared before and on the 3rd and 30th day after surgery. Results. There was no difference in age, sex and TNM stage between the two groups (P > 0.05). The number of metastatic lymph nodes in the experimental group (9.80 ± 4.80) was different from that in the control group (6.95 ± 3.86) (P < 0.05), and the number of metastatic lymph nodes in the experimental group was different from that in the control group (χ2 = 14.968, P < 0.05). There was no difference in blood calcium and PTH between the two groups before and at 3 and 30 days after surgery (P > 0. 05). Conclusion. The application of carbon nanoparticles in thyroid cancer surgery can significantly increase the number of lymph nodes seized and the positive rate of metastatic lymph node removal, but the protection of parathyroid gland is not obvious.