Secalonic acid D induces cell apoptosis in both sensitive and ABCG2-overexpressing multidrug resistant cancer cells through upregulating c-Jun expression

Secalonic acid D (SAD) could inhibit cell growth in not only sensitive cells but also multidrug resistant (MDR) cells. However, the molecular mechanisms need to be elucidated. Here, we identified that SAD possessed potent cytotoxicity in 3 pairs of MDR and their parental sensitive cells including S1-MI-80 and S1, H460/MX20 and H460, MCF-7/ADR and MCF-7 cells. Furthermore, SAD induced cell G2/M phase arrest the downregulation of cyclin B1 and the increase of CDC2 phosphorylation. Importantly, JNK pathway upregulated the expression of c-Jun in protein level and increased c-Jun phosphorylation induced by SAD, which was linked to cell apoptosis c-Jun/Src/STAT3 pathway. To investigate the mechanisms of upregulation of c-Jun protein by SAD, the mRNA expression level and degradation of c-Jun were examined. We found that SAD did not alter the mRNA level of c-Jun but inhibited its proteasome-dependent degradation. Taken together, these results implicate that SAD induces cancer cell death through c-Jun/Src/STAT3 signaling axis by inhibiting the proteasome-dependent degradation of c-Jun in both sensitive cells and ATP-binding cassette transporter sub-family G member 2 (ABCG2)-mediated MDR cells.

A β-catenin/IQGAP1 regulatory feedback loop and its effects on the proliferation of colon cancer cells / 生物医学工程学杂志

The aim of this article is to study the regulatory feedback loop between β-catenin and IQ motif containing GTPase activating protein 1 (IQGAP1), as well as the effect of this regulation loop in colon cancer cell proliferation. Western blot was used to detect the expression of IQGAP1 and β-catenin after changing their expression respectively by transfection in SW1116 cells. CCK-8 cell proliferation assay was used to detect the effect of IQGAP1 involved in the proliferation of SW1116 cells promoted by β-catenin. The results of Western blot indicated that β-catenin could positively regulate IQGAP1, while IQGAP1 silencing could up-regulate β-catenin, forming a negative feedback loop. The results of CCK-8 showed that IQGAP1 silencing inhibited β-catenin-mediated proliferation in SW1116 cells. In conclusion, our research reveals a negative regulatory feedback loop between β-catenin and IQGAP1 which has a remarkable effect on the proliferation ability of colon cancer cells.

Effect of left atrial enlargement on expression of the angiotensinⅡ, signal transducers and activators of transcription 3 and Rac GTPase activating protein 1 signaling pathways in patients with persistent atrial fibrillation and rheumatic heart disease / 中国胸心血管外科临床杂志

@#Objective To evaluate the effect of left atrial enlargement on atrial myocardial fibrosis degree and levels of the angiotensinⅡ (AngⅡ)/Rac GTPase activating protein 1 (Rac1)/signal transducersand activators of transcription 3 (STAT3) signaling pathways expressing in patients with persistent atrial fibrillation and rheumatic heart disease (RHD). Methods From March to December 2011, 30 patients with RHD who underwent prosthetic valve replacement in our hospital were enrolled, including 16 males and 14 females, aged 42-70 (56.9±6.8) years. Twenty RHD patients with persistent atrial fibrillation as a research group and ten RHD patients with sinus rhythm as a control group (group A) underwent transthoracic echocardiography and right atrial appendage (RAA) tissue samples were obtained from these patients during mitral/aortic valve replacement operation. The research group according to left atrial diameter (LAD) was divided into two groups, ten patients in each group: a group B with LAD of 50–65 mm and a group C with LAD of LAD>65 mm. For each sample, histological examination was performed by hematoxylin-eosin and Masson’s trichrome staining. Light-microscopic pictures of atrial tissues samples were stained and tissue fibrosis degree in each group was analyzed. AngⅡ concentration was measured by enzyme linked immunosorbent assay. Rac1 and STAT3 were measured by western blotting. Results LAD was significantly greater in AF patients with RHD than in the control group. Hematoxylin-eosin staining demonstrated highly organized arrangement of atrial muscles in the control group and significant derangement in both group B and group C with reduced cell density and increased cell size. Moreover, Masson’s trichrome staining showed that atrial myocytes were surrounded by large trunks of collagen fibers in both group B and group C, but not in the group A. There was a positive correlation between atrial tissue fibrosis and LAD. AngⅡ content was positively correlated with LAD. Similarly, Rac1 and STAT3 protein levels were found considerably higher in the group C and group B than in the group A with excellent correlation to LAD. Conclusion In patients with RHD complicated with persistent atrial fibrillation, the degree of atrial fibrosis and the expression level of AngⅡ/Rac1/STAT3 signaling pathways significantly increase with the left atrialenlargement.

SASH1-IQGAP1-E-cadherin signal cascade may regulate breast cancer metastasis / 肿瘤

Objective: To explore the molecular mechanism of SAM-and SH3-domain containing 1 (SASH1) which serves as a novel tumor suppressor gene to regulate breast cancer metastasis. Methods: The expressions of SASH1, IQ motif-containing GTPase activating protein 1 (IQGAP1) and E-cadherin in breast cancer tissues were analyzed by immunohistochemistry (IHC). The correlation among SASH1, IQGAP1 and E-cadherin, as well as the association of SASH1 and IQGAP1 expressions with the clinical parameters of breast cancer patients were analyzed, respectively. The recombinant plasmids HAIQGAP1-pcDNA3.0 and pEGFP-C3-SASH1 were cloned and transfected into human embryonic kidney HEK-293T cells. The interaction of SASH1 and IQGAP1 was analyzed by immunoprecipitation-Western blotting. Results: In breast cancer tissues, there was a correlation between the expressions of SASH1 and IQGAP1 (P 0.05). The recombinant plasmids HAIQGAP1-pcDNA3.0 and pEGFP-C3-SASH1 were constructed successfully. After these recombinant plasmids were transfected into HEK-293T cells, the interaction between SASH1 and IQGAP1 was found. Conclusion: SASH1 interacts with IQGAP1, and which is closely related to the expression of E-cadherin. Therefore, it is suggested that SASH1 may form a new signaling cascade with IQGAP1 and E-cadherin to regulate breast cancer metastasis.

Inhibitory Effect of Rosiglitazone on Inflammation in Paraquat-induced Lung Injury in Rats / 医药导报

Objective To study inhibition effect of rosiglitazone on lung injury induced by paraquat. Methods 72 male SD rats were randomly divided into three groups ( n=24 ): model control group, paraquat ( PQ ) was administered intraperitoneally at the dose of 20 mg·kg-1;rosiglitazone group, rosiglitazone (10 mg·kg-1 , ip) was administered 1 h before PQ administration; blank control group, 1 mL 0. 9% sodium chloride solution was administered intraperitoneally. The concentration of TNF-α and IL-1β in serum was measured by ELISA at 4, 8 h and 1, 3 day(s) after PQ exposure. The lung injury scores and nuclear factor-kappa B( NF-κB) positive signal were investigated 3 days after PQ exposure by HE staining and immunohistochemistry, respectively. Protein expression levels of NF-κB and activating protein-1(AP-1) were also determined by using Western blotting. Results The levels of IL-1β and TNF-α in serum of PQ-treated rats were significantly increased as compared with blank control group. Rosiglitazone pretreatment reduced the degree of lung tissue injury, the levels of IL-1β and TNF-α in serum, and the protien expression levels of NF-κB and AP-1 as compared with the model control group. Conclusion Rosiglitazone can inhibit NF-κB and AP-1 protein expression in lung tissue, reduce the levels of IL-1β and TNF-α in serum after PQ exposure, and exert an inhibition effect on inflammation in PQ-induced lung injury of rats.

Expression of Rap1 GTPase-activating protein 1, matrix metalloproteinase 2 and matrix metalloproteinase 9 in colorectal carcinoma and their significance / 肿瘤研究与临床

Objective To investigate the expression of Rap1 GTPase-activating protein 1 (Rap1GAP),matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9),and their relation with clinical patterns in colorectal carcinoma.Methods Immunohistochemistry was used to detect the expression of Rap1GAP,MMP-2 and MMP-9 in colorectal carcinoma,villous adenoma,tubular adenoma and normal colorectal tissue,and their relationship with clinicopathological parameters was analyzed.Results The positive rate of Rap1GAP expression was 30.4 ％ (14/46),77.8 ％ (14/18),69.6 ％ (16/23) and 95.2 ％ (20/21) in colorectal carcinoma,villous adenoma,tubular adenoma,and normal colorectal tissue,respectively (x2 =30.659,P=0.000).The figures were 71.7 ％ (33/46),55.6 ％ (10/18),52.2 ％ (12/16) and 9.5 ％ (2/21) for the positive rate of MMP-2 expression (x2 =22.459,P =0.000),as well as for 76.1％ (35/46),61.1％ (11/18),56.5 ％ (13/23) and 14.3 ％ (3/21) for the positive rate of MMP-9 expression,respectively (x2 =22.643,P =0.000).In patients with colorectal carcinoma,the expression of Rap1GAP was correlated with tumor differentiation (x2 =5.275,P =0.022),but not sex,age,or lymphatic metastasis (all P ＞ 0.05).The expression of MMP-2 and MMP-9 were correlated with lymphatic metastasis (x2 =6.661,P =0.010;x2 =8.475,P =0.040),but not sex,age or tumor differentiation(all P ＞ 0.05).There was a negative correlation between expression of Rap1GAP and MMP-2,MMP-9 in colorectal carcinoma,respectively (r =-0.424,P =0.003;r =-0.294,P =0.048),but no correlation between the expression of MMP-2 and MMP-9 (r =0.101,P =0.505).Conclusions Rap1GAP,MMP-2 and MMP-9 play important roles in the malignant biological behavior of colorectal carcinoma,and the expression of Rap1GAP is negatively correlated with MMP-2 and MMP-9.The interactions among the three affect the occurrence and development of colorectal carcinoma.