Mollugin

Biochem Biophys Res Commun. 2014 Jul 18;450(1):247-54.

Mollugin induces tumor cell apoptosis and autophagy via the PI3K/AKT/mTOR/p70S6K and ERK signaling pathways.[Pubmed: 24887566]

Mollugin, a bioactive phytochemical isolated from Rubia cordifolia L., has shown preclinical anticancer efficacy in various cancer models. However the effects of Mollugin in regulating cancer cell survival and death remains undefined.
METHODS AND RESULTS:
In the present study we found that Mollugin exhibited cytotoxicity on various cancer models. The suppression of cell viability was due to the induction of mitochondria apoptosis. In addition, the presence of autophagic hallmarks was observed in Mollugin-treated cells. Notably, blockade of autophagy by a chemical inhibitor or RNA interference enhanced the cytotoxicity of Mollugin. Further experiments demonstrated that phosphatidylinositide 3-kinases/protein kinase B/mammalian target of rapamycin/p70S6 kinase (PI3K/AKT/mTOR/p70S6K) and extracellular regulated protein kinases (ERK) signaling pathways participated in Mollugin-induced autophagy and apoptosis.
CONCLUSIONS:
Together, these findings support further studies of Mollugin as candidate for treatment of human cancer cells.

Phytomedicine. 2015 Jan 15;22(1):27-35.

Mollugin from Rubea cordifolia suppresses receptor activator of nuclear factor-κB ligand-induced osteoclastogenesis and bone resorbing activity in vitro and prevents lipopolysaccharide-induced bone loss in vivo.[Pubmed: 25636867]

Osteopenic diseases, such as osteoporosis, are characterized by progressive and excessive bone resorption mediated by enhanced receptor activator of nuclear factor-κB ligand (RANKL) signaling. Therefore, downregulation of RANKL downstream signals may be a valuable approach for the treatment of bone loss-associated disorders.
METHODS AND RESULTS:
In this study, we investigated the effects of the naphthohydroquinone Mollugin on osteoclastogenesis and its function in vitro and in vivo. Mollugin efficiently suppressed RANKL-induced osteoclast differentiation of bone marrow macrophages (BMMs) and bone resorbing activity of mature osteoclasts by inhibiting RANKL-induced c-Fos and NFATc1 expression. Mollugin reduced the phosphorylation of signaling pathways activated in the early stages of osteoclast differentiation, including the MAP kinase, Akt, and GSK3β and inhibited the expression of different genes associated with osteoclastogenesis, such as OSCAR, TRAP, DC-STAMP, OC-STAMP, integrin αν, integrin β3, cathepsin K, and ICAM-1. Furthermore, mice treated with Mollugin showed significant restoration of lipopolysaccharide (LPS)-induced bone loss as indicated by micro-CT and histological analysis of femurs.
CONCLUSIONS:
Consequently, these results suggested that Mollugin could be a novel therapeutic candidate for bone loss-associated disorders including osteoporosis, rheumatoid arthritis, and periodontitis.

Biol Pharm Bull. 2013;36(3):399-406. Epub 2013 Jan 11.

Mollugin inhibits the inflammatory response in lipopolysaccharide-stimulated RAW264.7 macrophages by blocking the Janus kinase-signal transducers and activators of transcription signaling pathway.[Pubmed: 23318249]

Mollugin, a kind of naphthohydroquinone, is a major constituent isolated from Rubia cordifolia L. and demonstrated to possess anti-inflammatory activity in recent reports. However, the effects and mechanism of action of Mollugin in inflammation have not been fully defined. The present study was therefore designed to investigate whether Mollugin suppresses the inflammatory response in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages.
METHODS AND RESULTS:
Mollugin attenuated the LPS-induced expression of nitric oxide (NO), inducible nitric oxide synthase (iNOS), interleukin (IL)-1β and IL-6 but augmented the expression of tumor necrosis factor (TNF)-α. Mollugin did not inhibit the degradation of inhibitory kappa B (IκB)-α or the nuclear translocation of p65 nuclear factor-kappa B (NF-κB) but rather enhanced the phosphorylation of p65 subunits evoked by LPS. Mollugin did not inhibit the phosphorylation of extracellular-signal-related kinase (ERK) 1/2, p38, and c-Jun N-terminal kinase (JNK) 1/2 either. Mollugin significantly reduced the LPS-mediated phosphorylation of Janus kinase (JAK) 2, signal transducers and activators of transcription (STAT) 1 and STAT3. Molecular docking analysis showed that Mollugin binds to JAK2 in a manner similar to that of AG490, a specific JAK2 inhibitor.
CONCLUSIONS:
We conclude that Mollugin may be a JAK2 inhibitor and inhibits LPS-induced inflammatory responses by blocking the activation of the JAK-STAT pathway.

J Cell Physiol. 2013 May;228(5):1087-97.

Mollugin inhibits proliferation and induces apoptosis by suppressing fatty acid synthase in HER2-overexpressing cancer cells.[Pubmed: 23065756]

Mollugin is a naphthohydroquine found in the roots of Rubia cordifolia, and has been reported to have a variety of biological activities, including anti-inflammatory and apoptotic effects. In the present study, we investigated the molecular mechanisms by which Mollugin exerts anti-tumor effect in HER2-overexpressing cancer cells.
METHODS AND RESULTS:
Our results showed that Mollugin exhibited potent inhibitory effects on cancer cell proliferation, especially in HER2-overexpressing SK-BR-3 human breast cancer cells and SK-OV-3 human ovarian cancer cells in a dose- and time-dependent manner without affecting immortalized normal mammary epithelial cell line MCF-10A. Furthermore, we found that a blockade of Akt/SREBP-1c signaling through Mollugin treatment significantly reduced FAS expression and subsequently suppressed cell proliferation and induced apoptosis in HER2-overexpressing cancer cells. Mollugin treatment caused a dose-dependent inhibition of HER2 gene expression at the transcriptional level, potentially in part through suppression of NF-κB activation. The combination of Mollugin with a MEK1/2 inhibitor may be required in order to achieve optimal efficacy in HER2-overexpressing cancers. These data provide evidence that Mollugin inhibits proliferation and induces apoptosis in HER2-overexpressing cancer cells by blocking expression of the FAS gene through modulation of a HER2/Akt/SREBP-1c signaling pathway.
CONCLUSIONS:
Our findings suggest that Mollugin is a novel modulator of the HER2 pathway in HER2-overexpressing cancer cells with a potential role in the treatment and prevention of human breast and ovarian cancer with HER2 overexpression.

Biomed Res Int. 2013;2013:210604.

Involvement of Nrf2-mediated upregulation of heme oxygenase-1 in mollugin-induced growth inhibition and apoptosis in human oral cancer cells.[Pubmed: 23738323]

Although previous studies have shown that Mollugin, a bioactive phytochemical isolated from Rubia cordifolia L. (Rubiaceae), exhibits antitumor effects, its biological activity in oral cancer has not been reported.
METHODS AND RESULTS:
We thus investigated the effects and putative mechanism of apoptosis induced by Mollugin in human oral squamous cell carcinoma cells (OSCCs). Results show that Mollugin induces cell death in a dose-dependent manner in primary and metastatic OSCCs. Mollugin-induced cell death involved apoptosis, characterized by the appearance of nuclear shrinkage, flow cytometric analysis of sub-G1 phase arrest, and annexin V-FITC and propidium iodide staining. Western blot analysis and RT-PCR revealed that Mollugin suppressed activation of NF- κ B and NF- κ B-dependent gene products involved in antiapoptosis (Bcl-2 and Bcl-xl), invasion (MMP-9 and ICAM-1), and angiogenesis (FGF-2 and VEGF). Furthermore, Mollugin induced the activation of p38, ERK, and JNK and the expression of heme oxygenase-1 (HO-1) and nuclear factor E2-related factor 2 (Nrf2). Mollugin-induced growth inhibition and apoptosis of HO-1 were reversed by an HO-1 inhibitor and Nrf2 siRNA.
CONCLUSIONS:
Collectively, this is the first report to demonstrate the effectiveness of Mollugin as a candidate for a chemotherapeutic agent in OSCCs via the upregulation of the HO-1 and Nrf2 pathways and the downregulation of NF- κ B.