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Inhibition of Hec1 expression enhances the sensitivity of human ovarian cancer cells to paclitaxel.

ABSTRACT: AIM: Hec1, a member of the Ndc80 kinetochore complex, is highly expressed in cancers. The aim of this study was to explore the role and mechanism of action of Hec1 with respect to the cytotoxicity of paclitaxel in ovarian cancer. METHODS: Thirty ovarian cancer samples and 6 normal ovarian samples were collected. Hec1 expression in these samples was determined with immunohistochemistry. Ovarian cancer cell lines A2780, OV2008, C13K, SKOV3, and CAOV3 and A2780/Taxol were examined. Cell apoptosis and cell cycle analysis were detected with flow cytometric technique. siRNA was used to delete Hec1 in the cells. The expression of related mRNAs and proteins was measured using RT-PCR and Western blot analysis, respectively. RESULTS: Hec1 expression was significantly higher in ovarian cancer samples than in normal ovarian samples, and was associated with paclitaxel-resistance and poor prognosis. Among the 6 ovarian cancer cell lines examined, Hec1 expression was highest in paclitaxel-resistant A2780/Taxol cells, and lowest in A2780 cells. Depleting Hec1 in A2780/Taxol cells with siRNA decreased the IC50 value of paclitaxel by more than 10-fold (from 590±26.7 to 45.6±19.4 nmol/L). Depleting Hec1 in A2780 cells had no significant effect on the paclitaxel sensitivity. In paclitaxel-treated A2780/Taxol cells, depleting Hec1 significantly increased the cleaved PARP and Bax protein levels, and decreased the Bcl-xL protein level. CONCLUSION: Hec1 overexpression is associated with the progression and poor prognosis of ovarian cancer. Inhibition of Hec1 expression can sensitize ovarian cancer cells to paclitaxel.

SUBMITTER: Mo QQ

PROVIDER: S-EPMC4002790 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Inhibition of Hec1 expression enhances the sensitivity of human ovarian cancer cells to paclitaxel.

Mo Qing-qing QQ Chen Ping-bo PB Jin Xin X Chen Qian Q Tang Lan L Wang Bei-bei BB Li Ke-zhen KZ Wu Peng P Fang Yong Y Wang Shi-xuan SX Zhou Jian-feng JF Ma Ding D Chen Gang G

Acta pharmacologica Sinica 20130311 4

<h4>Aim</h4>Hec1, a member of the Ndc80 kinetochore complex, is highly expressed in cancers. The aim of this study was to explore the role and mechanism of action of Hec1 with respect to the cytotoxicity of paclitaxel in ovarian cancer.<h4>Methods</h4>Thirty ovarian cancer samples and 6 normal ovarian samples were collected. Hec1 expression in these samples was determined with immunohistochemistry. Ovarian cancer cell lines A2780, OV2008, C13K, SKOV3, and CAOV3 and A2780/Taxol were examined. Cel ...[more]

PMID: 23474708

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Project description:BackgroundPaclitaxel (PTX), a first-line therapy for triple negative breast cancers (TNBC) induces anti-tumor activity by microtubule stabilization and inhibition of cell division. Its dose-limiting toxicity and short half-life, however, pose clinical challenges underscoring the need for strategies that increase its efficiency. RAD6, a E2 ubiquitin conjugating enzyme, is associated with centrosomes at all phases of cell cycle. Constitutive overexpression of the RAD6B homolog in normal breast cells induces centrosome amplification and multipolar spindle formation, indicating its importance in centrosome regulation.MethodsTNBC centrosome numbers were scored by pericentrin immunostaining. PTX sensitivities and interactions with SMI#9, a RAD6-selective small molecule inhibitor, on TNBC cell survival were analyzed by MTT and colony forming assays and an isogenic MDA-MB-468 TNBC model of PTX resistance. The molecular mechanisms underlying PTX and SMI#9 induced cytotoxicity were determined by flow cytometry, immunoblot analysis of cyclin B1 and microtubule associated protein TAU, and dual immunofluorescence staining of TAU and α-tubulin.ResultsOur data show aberrant centrosome numbers and that PTX sensitivities are not correlated with TNBC BRCA1 status. Combining PTX with SMI#9 synergistically enhances PTX sensitivities of BRCA1 wild-type and mutant TNBC cells. Whereas SMI#9/PTX combination treatment increased cyclin B1 levels in MDA-MB-468 cells, it induced cyclin B1 loss in HCC1937 cells with accumulation of reproductively dead giant cells, a characteristic of mitotic catastrophe. Cell cycle analysis revealed drug-induced accumulation of tetraploid cells in S and G2/M phases, and robust increases in cells with 4 N DNA content in HCC1937 cells. TAU overexpression is associated with reduced PTX efficacy. Among the six TAU isoforms, both SMI#9 and PTX downregulated 1N3R TAU in MDA-MB-468 and HCC1937 cells, suggesting a common mechanism of 1N3R regulation. Dual TAU and α-tubulin immunostaining showed that SMI#9 induces monopolar mitotic spindles. Using the isogenic model of PTX resistance, we show that SMI#9 treatment restores PTX sensitivity.ConclusionsThese data support a common mechanism of microtubule regulation by SMI#9 and PTX and suggest that combining PTX with RAD6 inhibitor may be beneficial for increasing TNBC sensitivities to PTX and alleviating toxicity. This study demonstrates a new role for RAD6 in regulating microtubule dynamics.

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Inhibition of Hec1 expression enhances the sensitivity of human ovarian cancer cells to paclitaxel.

Publications

Inhibition of Hec1 expression enhances the sensitivity of human ovarian cancer cells to paclitaxel.

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