Bioelectronics of The Cellular Cytoskeleton: Monitoring Cytoskeletal Conductance Variation for Sensing Drug Resistance

Actin and microtubules form cellular cytoskeletal network, which mediates cell shape, motility and proliferation and are key targets for cancer therapy. Changes in cytoskeletal organization dramatically affect mechanical properties of the cells and correlate with proliferative capacity and invasiveness of cancer cells. Changes in the cytoskeletal network expectedly lead to altered nonmechanical material properties including electrical conductivity as well. Here we applied, for the first time, microtubule and actin based electrical measurement to monitor changes in the electrical properties of breast cancer cells upon administration of anti-tubulin and anti-actin drugs, respectively. Semiconductive behavior of microtubules and conductive behavior of actins presented different bioelectrical responses (in similar frequencies) of the cells treated by anti-tubulin with respect to anti-actin drugs. Doped silicon nanowires were applied as the electrodes due to their enhanced interactive surface and compatibility with electronic fabrication process. We found that treatment with Mebendazole (MBZ), a microtubule destabilizing agent, decreases electrical resistance while treatment with Paclitaxel (PTX), a microtubule stabilizing agent, leads to an increase in electrical resistance. In contrast, actin destabilizing agents, Cytochalasin D (CytD), and actin stabilizing agent, Phalloidin, lead to an increased and decreased electrical resistance, respectively. Our study thus provides proof-of-principle of the usage of determining the electrical function of cytoskeletal compartments in grading of cancer as well as drug resistance assays.

Gallic acid and curcumin induce cytotoxicity and apoptosis in human breast cancer cell MDA-MB-231

Introduction: Gallic acid (GA) and curcumin (Cur) are natural phenolic compounds that their anti-tumor effects on many types of cancers have been proved. In the current study, the effect of the combination of these agents on MDA-MB-231 breast cancer cells was investigated.

Methods: Inhibition of cell proliferation (MTT assay), light microscopy, fluorescence microscopy, cell cycle analysis, nitrite detection, ROS levels, measurement of the mitochondrial membrane potential, GSH level, Annexin V assay, RT-PCR and Western blotting methods were applied.

Results: The results revealed the combination of GA and Cur strongly decreased MDA-MB-231 cell growth. Moreover, this combination increased ROS level and cytotoxic activity along with the glutathione depletion in MDA-MB-231 cells. Flow cytometry analysis showed the combination of GA and Cur increased sub-G1 cell population. Furthermore, fluorescent staining and Annexin V/PI assay showed that apoptotic cells were significantly increased in the presence of GA and Cur. At last, protein expression evaluation showed that the combination of GA and Cur significantly decreased Bcl-2 level while increased Bax, cleaved-caspase3 and PARP levels in MDA-MB-231 cells.

Conclusion: These results suggest that GA in combination with Cur could be a possible candidate for chemoprevention agent of triple negative breast cancer.

Combination of arabinogalactan and curcumin induces apoptosis in breast cancer cells in vitro and inhibits tumor growth via overexpression of p53 level in vivo

PURPOSE

Increased mortality associated with breast cancer in women has spurred the studies to develop new drugs. Arabinogalactan (AG) and curcumin (Cur) are two natural products broadly explored in cancer therapy. Our major goal in the current study was to assess anticancer properties of combination these reagents in vitro on human breast cancer cells and in vivo utilizing animal model of breast cancer.

EXPERIMENTAL DESIGN

We evaluated cell proliferation, apoptosis, cell cycle, and protein expression in vitro on MDA-MB-231 human breast cancer cells. For in vivo studies, murine breast cancer cells were implanted into BALB/c mice. Thereafter, volume of the developing tumor was calculated and expression of Ki67 and p53 proteins was evaluated to analyze cell proliferation and apoptosis.

RESULTS

Combination of AG and Cur significantly decreased cell growth in human breast cancer cells without any significant effect on normal cell growth. This combination could increase cell population in sub-G1 phase, which was indicative of apoptosis. Western blotting showed that the combination of AG and Cur significantly increased Bax/Bcl2 ratio as well as cleaved-caspase3 level in MDA-MB-231 cells. Combination of AG and Cur promoted apoptosis by increasing ROS level, changing mitochondrial membrane and reduction of glutathione. In addition, in vivo studies in mouse showed that this combination could inhibit the progression of breast tumors through over-expression of p53 and reduction of Ki67 levels.

CONCLUSION

Our findings suggest that the combination of AG and Cur is of great potential to induce apoptosis in breast cancer cells in vitro and in vivo.