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Gao, Yan

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Gao

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Yan

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Gao, Yan

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2015 - 20164

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Author's Publications: search.filters.isAuthorOfPublication.1250956c-6c89-45df-a251-9b3ec066d20a

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Now showing 1 - 4 of 4
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    Pharmacokinetics and tolerability of NSC23925b, a novel P-glycoprotein inhibitor: preclinical study in mice and rats
    (Nature Publishing Group, 2016) Gao, Yan; Shen, Jacson K.; Choy, Edwin; Zhang, Zhan; Mankin, Henry; Hornicek, Francis; Duan, Zhenfeng
    Overexpression of P-glycoprotein (Pgp) increases multidrug resistance (MDR) in cancer, which greatly impedes satisfactory clinical treatment and outcomes of cancer patients. Due to unknown pharmacokinetics, the use of Pgp inhibitors to overcome MDR in the clinical setting remains elusive despite promising in vitro results. The purpose of our current preclinical study is to investigate the pharmacokinetics and tolerability of NSC23925b, a novel and potent P-glycoprotein inhibitor, in rodents. Plasma pharmacokinetic studies of single-dose NSC23925b alone or in combination with paclitaxel or doxorubicin were conducted in male BALB/c mice and Sprague-Dawley rats. Additionally, inhibition of human cytochrome P450 (CYP450) by NSC23925b was examined in vitro. Finally, the maximum tolerated dose (MTD) of NSC23925b was determined. NSC23925b displayed favorable pharmacokinetic profiles after intraperitoneal/intravenous (I.P./I.V.) injection alone or combined with chemotherapeutic drugs. The plasma pharmacokinetic characteristics of the chemotherapy drugs were not affected when co-administered with NSC23925b. All the animals tolerated the I.P./I.V. administration of NSC23925b. Moreover, the enzymatic activity of human CYP450 was not inhibited by NSC23925b. Our results demonstrated that Pgp inhibitor NSC23925b exhibits encouraging preclinical pharmacokinetic characteristics and limited toxicity in vivo. NSC23925b has the potential to treat cancer patients with MDR in the future.
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    Up-regulation of CD44 in the development of metastasis, recurrence and drug resistance of ovarian cancer
    (Impact Journals LLC, 2015) Gao, Yan; Foster, Rosemary; Yang, Xiaoqian; Feng, Yong; Shen, Jacson K.; Mankin, Henry; Hornicek, Francis; Amiji, Mansoor M.; Duan, Zhenfeng
    The clinical significance of Cluster of Differentiation 44 (CD44) remains controversial in human ovarian cancer. The aim of this study is to evaluate the clinical significance of CD44 expression by using a unique tissue microarray, and then to determine the biological functions of CD44 in ovarian cancer. In this study, a unique ovarian cancer tissue microarray (TMA) was constructed with paired primary, metastatic, and recurrent tumor tissues from 26 individual patients. CD44 expression in TMA was assessed by immunohistochemistry. Both the metastatic and recurrent ovarian cancer tissues expressed higher level of CD44 than the patient-matched primary tumor. A significant association has been shown between CD44 expression and both the disease free survival and overall survival. A strong increase of CD44 was found in the tumor recurrence of mouse model. Finally, when CD44 was knocked down, proliferation, migration/invasion activity, and spheroid formation were significantly suppressed, while drug sensitivity was enhanced. Thus, up-regulation of CD44 represents a crucial event in the development of metastasis, recurrence, and drug resistance to current treatments in ovarian cancer. Developing strategies to target CD44 may prevent metastasis, recurrence, and drug resistance in ovarian cancer.
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    Expression of programmed cell death ligand 1 (PD-L1) and prevalence of tumor-infiltrating lymphocytes (TILs) in chordoma
    (Impact Journals LLC, 2015) Feng, Yong; Shen, Jacson; Gao, Yan; Liao, Yunfei; Cote, Gregory; Choy, Edwin; Chebib, Ivan; Mankin, Henry; Hornicek, Francis; Duan, Zhenfeng
    Chordomas are primary malignant tumors of the notochord that are resistant to conventional chemotherapy. Expression of programmed cell death ligand 1 (PD-L1), prevalence of tumor-infiltrating lymphocytes (TILs), and their clinical relevance in chordoma remain unknown. We evaluated PD-L1 expression in three chordoma cell lines and nine chordoma tissue samples by western blot. Immunohistochemical staining was performed on a chordoma tissue microarray (TMA) that contained 78 tissue specimens. We also correlated the expression of PD-L1 and TILs with clinical outcomes. PD-L1 protein expression was demonstrated to be induced by IFN-γ in both UCH1 and UCH2 cell lines. Across nine human chordoma tissue samples, PD-L1 protein was differentially expressed. 94.9% of chordoma samples showed positive PD-L1 expression in the TMA. The expression score of PD-L1 for metastatic chordoma tumors was significant higher as compared with non-metastatic chordoma tumors. Expression of PD-L1 protein significantly correlates with the presence of elevated TILs, which correlates with metastasis. In summary, our study showed high levels of PD-L1 are expressed in chordoma, which is correlated with the prevalence of TILs. The current study suggests targeting PD-L1 may be a novel immunotherapeutic strategy for chordoma clinical trials.
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    CD44 is a direct target of miR-199a-3p and contributes to aggressive progression in osteosarcoma
    (Nature Publishing Group, 2015) Gao, Yan; Feng, Yong; Shen, Jacson K.; Lin, Min; Choy, Edwin; Cote, Gregory; Harmon, David; Mankin, Henry; Hornicek, Francis; Duan, Zhenfeng
    Osteosarcoma is the most common primary bone malignancy in children and adolescents. Herein, we investigated the role of cluster of differentiation 44 (CD44), a cell-surface glycoprotein involved in cell-cell interactions, cell adhesion, and migration in osteosarcoma. We constructed a human osteosarcoma tissue microarray with 114 patient tumor specimens, including tumor tissues from primary, metastatic, and recurrent stages, and determined the expression of CD44 by immunohistochemistry. Results showed that CD44 was overexpressed in metastatic and recurrent osteosarcoma as compared with primary tumors. Higher expression of CD44 was found in both patients with shorter survival and patients who exhibited unfavorable response to chemotherapy before surgical resection. Additionally, the 3′-untranslated region of CD44 mRNA was the direct target of microRNA-199a-3p (miR-199a-3p). Overexpression of miR-199a-3p significantly inhibited CD44 expression in osteosarcoma cells. miR-199a-3p is one of the most dramatically decreased miRs in osteosarcoma cells and tumor tissues as compared with normal osteoblast cells. Transfection of miR-199a-3p significantly increased the drug sensitivity through down-regulation of CD44 in osteosarcoma cells. Taken together, these results suggest that the CD44-miR-199a-3p axis plays an important role in the development of metastasis, recurrence, and drug resistance of osteosarcoma. Developing strategies to target CD44 may improve the clinical outcome of osteosarcoma.