Molecular mechanism of anti-cancer activity of phycocyanin in triple-negative breast cancer cells.
BACKGROUND
Triple-negative breast cancers represent an important clinical challenge, as these cancers do not respond to conventional endocrine therapies or other available targeted agents. Phycocyanin (PC), a natural, water soluble and non-toxic molecule is shown to have potent anti-cancer property.


METHODS
In this study, we determined the efficacy of PC as an anti-neoplastic agent in vitro on a series of breast cancer cell lines. We studied effects of PC in inducing DNA damage and apoptosis through western blot and qPCR. Also, anti-metastatic and anti-angiogenic properties were studied by classic wound healing and vasculogenic mimicry assays.


RESULTS
We found that triple negative MDA-MB-231 cells were most sensitive to PC (IC50 : 5.98 ± 0.95 μM) as compared to other cells. They also showed decreased cell proliferation and reduced colony formation ability upon treatment with PC. Profile of Cell cycle analysis showed that PC caused G1 arrest which could be attributed to decreased mRNA levels of Cyclin E and CDK-2 and increased p21 levels. Mechanistic studies revealed that PC induced apoptosis as evident by increase in percentage of annexin positive cells, increase in γ-H2AX levels, and by changing the Bcl-2/Bax ratio followed by release of cytochrome C and increased Caspase 9 levels. MDA MB 231 cells treated with PC resulted in decreased cell migration and increased cell adhesive property and also showed anti-angiogenic effects. We also observed that PC suppressed cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) production. All these biological effects of phycocyanin on MDA MB 231 cells could be attributed to decreased MAPK signaling pathway. We also observed that PC is non-toxic to non-malignant cells, platelets and RBC's.


CONCLUSIONS
Taken together, these findings demonstrate, for the first time, that PC may be a promising anti-neoplastic agent for treatment of triple negative breast cancers.
Department of Human Genetics, Sri Ramachandra University, Chennai, 600116, India. matty_mir@yahoo.co.in.
Mathangi
M
Ravi
Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai, 600036, India. gsiitm011@gmail.com.
Shilpa
S
Tentu
Department of Human Genetics, Sri Ramachandra University, Chennai, 600116, India. ganga.baskar@gmail.com.
Ganga
G
Baskar
Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai, 600036, India. surabirohan@gmail.com.
Surabhi
S
Rohan Prasad
Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai, 600036, India. swetha.r@gmail.com.
Swetha
S
Raghavan
Department of Bioinformatics, Alagappa University, Karaikudi, India. prajishasujaya@gmail.com.
Prajisha
P
Jayaprakash
Department of Bioinformatics, Alagappa University, Karaikudi, India. jjkanthan@gmail.com.
Jeyaraman
J
Jeyakanthan
Department of Biotechnology, Indian Institute of Technology Madras (IITM), Chennai, 600036, India. rayala@iitm.ac.in.
Suresh K
SK
Rayala
Department of Human Genetics, Sri Ramachandra University, Chennai, 600116, India. ganeshv@sriramachandra.edu.in.
Ganesh
G
Venkatraman
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D053453:Caspase 9 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D058990:Molecular Targeted Therapy / Q000379:methods*; D010798:Phycocyanin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy*
D000970:Antineoplastic Agents; D010798:Phycocyanin; D051546:Cyclooxygenase 2; D053453:Caspase 9