ABSTRACT
Objective To investigate the role of epidermal growth factor receptor 3 (ErbB3) and insulin-like growth factor-1 receptor (IGF1R) in enhancing the resistance of Herceptin in human breast cancer.Methods HRG (Heregulin,the ligand of ErbB3) or IGF2 (insulin-like growth factor2,the ligand of IGF1R) was correspondingly added into breast cancer cells SKBR3 and BT474,and then 3-(4,5-dimenthylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and were performed in these cells to evaluate the sensitivity of these cells to Herceptin.Furthermore,we used HRG or IGF2 antibodies to inhibit their joint receptors in Herceptin-resistant breast cancer cells SKBR3/POOL2 and BT474/HR20.Finally,the sensitivity of these treated cells to Herceptin was detected via MTS assay.HRG or IGF2 was added into breast cancer cell BT474,and co-IP assay was used to detect the expressions of ErbB3 and IGF1R which combined with ErbB2.Results The treatment groups used HRG or IGF2 enhanced the resistance of Herceptin in Herceptin-sensitive breast cancer cells.On the other hand,we used antibodies of HRG and IGF2 to block their combining with their receptors in Herceptin-resistant breast cancer cells,the cells became more sensitive to Herceptin.BT474 cell was treated with HRG or IGF2.The expressions of ErbB3 and IGF1R which combined with ErbB2 were increased.Conclusions The formation of heterodimers ErbB2/ErbB3 and ErbB2/IGF1R might enhance the resistance of Herceptin in ErbB2-overexpression human breast cancers.
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Objective To explore the Cep70 by adjusting the stability of acetylated alpha tubulin,participate in breast cancer drug resistance mechanisms.Methods (1) In order to induce taxol drug resistance cell line Michigan cancer foundation-7 (MCF-7)/pac,high-dose shock treatments taxol MCF-7 was used for 6 months,until the cells can grow in 3.5 μmol/L of paclitaxel.(2) The 3-(4,5-dimenthylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) method was used to detect inhibition rate by taxol to MCF-7 and MCF-7/pac cell.(3) Immunofluorescence and Western blot were used to test acetylated alpha-tubulin and Cep70 expression levels in MCF-7 and MCF-7/pac cells.(4) Chemical intervention was used to acetylate apha-tubulin expression,Western blot and polymerase chain reaction (PCR) were used to detect the change of acetylated alpha-tubulin and Cep70 in MCF-7 and MCF-7/pac groups.Flow cytometry and Western blot were used to detect the change of cell cycle.Results (1) IC50 of MCF-7 and MCF-7/pac was 22.47 μ mol/L and 31.38 μmol/L,respectively.(2) Immunofluorescence and Western blot results showed that the expression of acetylation of alpha-tubulin in resistant MCF-7 cell/pac was obviously decreased.(3) Real time polymerase chain reaction (RT-PCR) and Western blot showed Cep70 expression was consistent of acetylation of alpha-tubulin.(4) After incubation with paclitaxel for 24 hours,the expressions of acetylation of alpha-tubulin and Cep70 in MCF-7 and MCF-7/pac were increased,but the extent of MCF-7 cell was much higher.Instead,incubation with nocodazole after 24 hours,the acetylation of alpha-tubulin and Cep70 in MCF-7 and MCF-7/pac cells were obviously lowered.(5) After paclitaxel intervention,compared to the same group MCF-7 cells,the G2 phase ratio in MCF-7/pac cells was lower.In addition,given nocodazole after the intervention,compared to the same group MCF-7 cells,the ratio of G2 phase in MCF-7 cell/pac was significantly decreased.Conclusions Cep70 decreased the expression of the acetylated alpha-tubulin,reduced the stability of microtubules,which could be an important mechanism of taxol drug resistance.
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Objective To explore the role of insulin-like growth factor-2/insulin-like growth factor1 receptor/insulin receptor substrate-1 (IGF2/IGF1R/IRS1) signal pathway inducing the chemoresistance of epidermal growth factor receptor 2 (ErbB2) positive breast cancer cells to Herceptin.Methods Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot assay were used to determine the expression levels of IGF2,IGF1 R,and IRS1.The direct targets of miR-126 were validated by dual-luciferase reporter gene assay.In SKBR3/pool2 cells,IGF1 R activity was reduced by an inhibitor of IGF1 R,and IRS1 was knocked-down by shRNAs.Furthermore,3-(4,5-dimenthylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay was performed to evaluate the sensitivity of these treated cells to Herceptin.Results IGF2,IGF1 R,and IRS1 were significantly higher expressed in SKBR3/pool2 cell compared to that in SKBR3 cell.Western blot assay showed that IGF2/IGF1R/IRS1 was activated in SKBR3/pool2 cells.Bioinformatics analysis combined with luciferase activity suggested that miR-126 directly targeted IRS1.MTS results demonstrated that the chemosensitivity to Herceptin of SKBR3/ pool2 cells with inhibitor of IGF1R or shRNAs targeting IRS1 or overexpressing miR-126 was significantly reduced.Conclusions IGF2/IGF1R/IRS1 signal pathway confers to the chemoresistance of ErbB2 positive breast cancer cells to Herceptin.
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ObjectiveTo evaluate the consistency of HER2 gene status before and after neoadjuvant chemotherapy in breast cancer by FISH (fluorescence in situ hybridization) and IHC (immunohistochemistry) techniques,and analyze the factor of the difference in the result and the feasibility of HER2 gene tested by FISH in the neoadjuvant chemotherapy breast cancer patients.Methods FISH and IHC for HER2 gene expression status was performed on the archival paraffin-embedded sections of breast cancer tissues before and after neoadjuvant chemotherapy from 135 Chinese female patients,x2 test of paired comparison of enumeration data and Kappa analysis were used to compare the difference and consistency of this two techniques.ResultsThe detection rate of HER2 status in punctured cancer tissues before neoadjuvant chemotherapy by FISH and HER2 did not show statistical difference in our research while the opposite result were showed in cancer tissues after neoadjuvant chemotherapy.Moreover,the two techniques of HER2 test were less concordant in patients accepted taxanes neoadjuvant chemotherapy than CAF treatment.ConclusionsThe consistency of FISH and IHC techniques of cancer tissues before neoadjuvant chemotherapy gained advantage compared to the ones after neoadjuvant chemotherapy.Patients received neoadjuvant chemotherapy especially taxanes should take the test of HER2 gene status by FISH technique.