TY - JOUR
T1 - Translocation of Bax to mitochondria induces apoptotic cell death in Indole-3-carbinol (I3C) treated breast cancer cells
AU - Rahman, K. M.Wahidur
AU - Aranha, Olivia
AU - Glazyrin, Alexey
AU - Chinni, Sreenivasa R.
AU - Sarkar, Fazlul H.
N1 - Funding Information:
We sincerely thank Ms Patricia Arlauskas for her editorial assistance. This project was partly funded by a pilot grant from NIEHS center grant (ES 06639) at Wayne State University, and the George Puschelberg Foundation awarded to FH Sarkar. We also thank Dr Kamiar Moin and Linda Mayernik for their invaluable assistance with the confocal microscopic imaging. Center Grants P30ES06639 from the National Institutes of Environmental Health Sciences. We would like to thank Erie Van Buren, Evano Piasentin and Dr Stephen Lerman for their assistance in the flow cytometry core facility, supported by the grant. P30CA22453 from the National Cancer Institute which supports this core facility at Wayne State University School of Medicine.
PY - 2000
Y1 - 2000
N2 - Epidemiological studies have suggested that the consumption of fruits and vegetables that provide several classes of compounds, including Indole-3-carbinol (I3C), may have chemopreventive activity against breast cancer. Several in vitro and in vivo animal studies also provide convincing evidence for the anti-tumor activity of I3C, however, the molecular mechanism(s) by which I3C exerts its biological effects on breast cancer cells has not been fully elucidated. In this study, we investigated the effects of I3C in Her-2/neu over-expressing MDA-MB-435 breast cancer cells and compared these results with parental cells transfected with control vector. We focused our investigation in elucidating the molecular mechanism(s) by which I3C induces apoptosis in breast cancer cells. Our data show that I3C inhibits breast cancer cell growth in a dose dependent manner in Her-2/neu overexpressing and in normal Her-2/neu expressing cells. Induction of apoptosis was also observed in these cell lines when treated with I3C, as measured by poly (ADP-ribose) polymerase (PARP) and caspase-3 activation. In addition, we found that I3C up-regulates Bax, down-regulates Bcl-2 and, thereby, increased the ratio of Bax to Bcl-2 favoring apoptosis. These results suggest that the alteration in the expression of these genes may play an important role in mediating the biological effects of I3C. Moreover, we also show the cellular localization of Bax by confocal microscopy, which showed diffuse distribution of Bax throughout the cytoplasmic compartment in breast cancer cells in control culture. However, in I3C treated cells, Bax showed a punctate pattern of distribution that was localized in the mitochondria. From these results, we conclude that the over-expression and translocation of Bax to mitochondria causes mitochondrial depolarization and activation of caspases, which may be one of the mechanism(s) by which I3C induces apoptotic processes in I3C treated breast cancer cells. Overall, our present data provide a novel molecular mechanism(s) by which I3C elicits its biological effects on both Her-2/neu over-expressing and with normal Her-2/neu expressing breast cancer cells, suggesting that I3C could be an effective agent in inducing apoptosis in breast cancer cells.
AB - Epidemiological studies have suggested that the consumption of fruits and vegetables that provide several classes of compounds, including Indole-3-carbinol (I3C), may have chemopreventive activity against breast cancer. Several in vitro and in vivo animal studies also provide convincing evidence for the anti-tumor activity of I3C, however, the molecular mechanism(s) by which I3C exerts its biological effects on breast cancer cells has not been fully elucidated. In this study, we investigated the effects of I3C in Her-2/neu over-expressing MDA-MB-435 breast cancer cells and compared these results with parental cells transfected with control vector. We focused our investigation in elucidating the molecular mechanism(s) by which I3C induces apoptosis in breast cancer cells. Our data show that I3C inhibits breast cancer cell growth in a dose dependent manner in Her-2/neu overexpressing and in normal Her-2/neu expressing cells. Induction of apoptosis was also observed in these cell lines when treated with I3C, as measured by poly (ADP-ribose) polymerase (PARP) and caspase-3 activation. In addition, we found that I3C up-regulates Bax, down-regulates Bcl-2 and, thereby, increased the ratio of Bax to Bcl-2 favoring apoptosis. These results suggest that the alteration in the expression of these genes may play an important role in mediating the biological effects of I3C. Moreover, we also show the cellular localization of Bax by confocal microscopy, which showed diffuse distribution of Bax throughout the cytoplasmic compartment in breast cancer cells in control culture. However, in I3C treated cells, Bax showed a punctate pattern of distribution that was localized in the mitochondria. From these results, we conclude that the over-expression and translocation of Bax to mitochondria causes mitochondrial depolarization and activation of caspases, which may be one of the mechanism(s) by which I3C induces apoptotic processes in I3C treated breast cancer cells. Overall, our present data provide a novel molecular mechanism(s) by which I3C elicits its biological effects on both Her-2/neu over-expressing and with normal Her-2/neu expressing breast cancer cells, suggesting that I3C could be an effective agent in inducing apoptosis in breast cancer cells.
KW - Apoptosis
KW - Bax
KW - Cell growth inhibition
KW - I3C
KW - Mitochondria
UR - http://www.scopus.com/inward/record.url?scp=0034706910&partnerID=8YFLogxK
U2 - 10.1038/sj.onc.1203959
DO - 10.1038/sj.onc.1203959
M3 - Article
C2 - 11126363
AN - SCOPUS:0034706910
SN - 0950-9232
VL - 19
SP - 5764
EP - 5771
JO - Oncogene
JF - Oncogene
IS - 50
ER -