Riris Istighfari Jenie

Increased ubiquitination and the crosstalk of G protein signaling in cardiac myocytes: involvement of Ric-8B in Gs suppression by Gq signal.

Hyperactivation of Gq signaling causes cardiac hypertrophy, and β‐adrenergic receptor‐mediated Gs signaling is attenuated in hypertrophic cardiomyocytes. Here, we found the increase in a global ubiquitination in hypertrophic mouse heart. The activation of Gq signaling resulted in the ubiquitination of Gαs in neonatal rat cardiomyocytes, reduced Gαs expression, and suppressed cAMP response to β‐adrenergic receptor stimulation. Ectopic expression of Gαq induced a similar suppression, which is due to the degradation of Gαs by a ubiquitin–proteasome pathway. Co‐expression of Ric‐8B, a positive regulator of Gαs, effectively canceled the Gαq‐induced ubiquitination of Gαs and recovered the cAMP accumulation. In vitro, Gαq competes for the binding of Gαs to Ric‐8B. These data show a new role of Ric‐8B in the crosstalk of two distinct G protein signaling pathways, which are possibly involved in a part of mechanisms of chronic heart failure.

Two Active Compounds from Caesalpinia sappan L. in Combination withCisplatin Synergistically Induce Apoptosis and Cell Cycle Arrest on WiDr Cells

Purpose: The aim of this study is to observe the synergistic effect of two active compounds of secang, brazilin and brazilein, combined with cisplatin on WiDr colon cancer cells. Methods: Cytotoxic activities of brazilin (Bi) and brazilein (Be) in single and in combination with cisplatin (Cisp) were examined by MTT assay. Synergistic effect was analyzed by combination index (CI) parameter. Apoptosis and cell cycle profiles were observed by using flow cytometry. Results: The result of MTT assay showed that IC50 value of brazilin and brazilein on WiDr cancer cells were 41 µM and 52 µM respectively. The combination of ½ IC50 of Bi-Cisp reduced cells viability up to 64% and showed synergistic effect with CI value less than 1 (CI = 0.8). The combinations of ½ IC50 of Be-Cisp also reduced cells viability up to 78% and showed synergistic effect (CI=0.65). Combination of Bi-Cisp and Be-Cisp induced apoptosis higher than the single treatments. Further analysis on the cell cycle progression showed that single treatment of ½ IC50 of Be and Bi induced S-phase and G2/M-phase accumulation, while combination of Be-Cisp and Bi-Cisp enhanced S-phase accumulation. Conclusion: Both combination of Bi-Cisp and Be-Cisp showed synergistic effect on WiDr cells through induction of apoptosis and halted the cell cycle progression, thus, WiDr cells growth were significantly reduced.

Enhancement of Cytotoxicity and Apoptosis Induction of Doxorubicin by Brazilein Containing Fraction of Secang (Caesalpinia sappan L.) on T47D Cells

Combination chemotherapy (co-chemotherapy) is a recent strategy to reduce the toxicity effect and increase the effectivity of chemotherapeutic agent, such as Doxorubicin (Dox). Caesalpinia sappan L. are potential to be developed as co-chemoterapeutic agents due to its strong cytotoxicity toward several breast cancer cells. The purpose of this research is to observe the cytotoxicity of Brazilein containing fraction (BCF) in single and its combination with doxorubicin on T47D cells. BCF was obtained by fractionation using chloroform:ethyl acetate (40:60 v/v) as mobile phase. Molecular docking results showed that Brazilein and Brazilin interacted with Bcl-2 with different binding properties. Based on MTT assay, Dox and BCF performed potent cytotoxicity with IC 50 value of 403 nM and 68 μg/mL, respectively. BCF increased the cytotoxicity of Dox and performed synergism with CI value 1. Under Annexin V PI staining Flowcytometry, BCF in single and its combination with doxorubicin induced apoptosis. In conclusion, single treatment of BCF and its combination with Dox performed cytotoxic effect and induced apoptosis on T47D cell lines. Keywords : Brazilein containing fraction, Doxorubicin, Co-chemoteraphy, Apoptosis, T47D cells

The Cytotoxic and Antimigratory Activity of Brazilin-Doxorubicin on MCF-7/HER2 Cells

Purpose: Breast cancer cells with overexpression of HER2 are known to be more aggressive, invasive, and resistant to chemotherapeutic agent. Brazilin, the major compound in the Caesalpinia sappan L. (CS) heartwood, has been studied for its anticancer activity. The purpose of this study was to investigate the cytotoxic and antimigratory activity of brazilin (Bi) in combination with doxorubicin (Dox) on MCF-7/HER2 cells. Methods: Cytotoxic activities of Bi individually and in combination with Dox were examined by MTT assay. Synergistic effects were analyzed by combination index (CI). Apoptosis and cell cycle profiles were observed by using flow cytometry. Migrating and invading cells were observed by using a Boyden chamber assay. Levels of MMP2 and MMP9 activity were observed by using a gelatin zymography assay. Levels of HER2, Bcl-2, Rac1, and p120 protein expression were observed by using an immunoblotting assay. Results: The results of the MTT assay showed that Bi inhibited MCF-7/HER2 cell growth in a dose-dependent manner with an IC50 of 54 ± 3.7 µM. Furthermore, the combination of Bi and Dox showed a synergistic effect (CI <1). Flow cytometric analysis of Bi and its combination with Dox showed cellular accumulation in the G2/M phase and induction of apoptosis through suppression of Bcl-2 protein expression. In the Boyden chamber assay, gelatin zymography, and subsequent immunoblotting assay, the combination Bi and Dox inhibited migration, possibly through downregulation of MMP9, MMP2, HER2, Rac1, and p120 protein expression. Conclusion: We conclude that Bi enhanced cytotoxic activity of Dox and inhibited migration of MCF-7/HER2 cells. Therefore, we believe that it has strong potential to be developed for the treatment of metastatic breast cancer with HER2 overexpression.