Structural insights into interacting mechanism of ID1 protein with an antagonist ID1/3-PA7 and agonist ETS-1 in treatment of ovarian cancer: molecular docking and dynamics studies.

Among the many abnormally expressed proteins in ovarian cancer, the prominent cancer in women, ID1 (inhibitors of DNA binding protein 1) is a potential one among other several targets. Interaction of ID1 with ETS-1 (transcriptional activator of p16(INK4a)) suppresses the transcription of p16(INK4a) and causes abnormal cell proliferation. A peptide aptamer (ID1/3-PA7) has been designed to prevent this interaction and thereby leading to the transcription of p16(INK4a). However, the structural basis behind the molecular interaction of ID1 with ETS-1 (agonist) and ID1/3-PA7 (antagonist) is poorly understood. In order to understand this structural recognition and their interaction mechanism, in silico methods were used. From this interaction analysis, the residues of ETS-1 involved in interaction with the p16(INK4a) promoter were found to be targeted by ID1. Subsequently, ETS-1 binding residues of ID1 were found to be targeted by its aptamer- ID1/3-PA7. These results suggest that both ETS-1 and ID1/3-PA7 binds at the same region harbored by the residues-H97, D100, R103, D104, L107, A144, C145, D149, D150 and C154 of ID1. All these observations correlate with the experimental reports, suggesting that the identified residues might play a crucial role in promulgating the oncogenic effects of ID1. In silico alanine scanning mutagenesis also confirms the role of identified hot spot residues in p16(INK4a) regulation. Finally, the molecular dynamic simulation studies reveal the prolonged stability of the aforementioned interacting complexes. The obtained results throw light on the structure and residues of ID1 involved in transcriptional regulation of p16(INK4a).

Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis.

Invasion and metastasis of aggressive breast cancer cells are the final and fatal steps during cancer progression. Clinically, there are still limited therapeutic interventions for aggressive and metastatic breast cancers available. Therefore, effective, targeted, and non-toxic therapies are urgently required. Id-1, an inhibitor of basic helix-loop-helix transcription factors, has recently been shown to be a key regulator of the metastatic potential of breast and additional cancers. We previously reported that cannabidiol (CBD), a cannabinoid with a low toxicity profile, down-regulated Id-1 gene expression in aggressive human breast cancer cells in culture. Using cell proliferation and invasion assays, cell flow cytometry to examine cell cycle and the formation of reactive oxygen species, and Western analysis, we determined pathways leading to the down-regulation of Id-1 expression by CBD and consequently to the inhibition of the proliferative and invasive phenotype of human breast cancer cells. Then, using the mouse 4T1 mammary tumor cell line and the ranksum test, two different syngeneic models of tumor metastasis to the lungs were chosen to determine whether treatment with CBD would reduce metastasis in vivo. We show that CBD inhibits human breast cancer cell proliferation and invasion through differential modulation of the extracellular signal-regulated kinase (ERK) and reactive oxygen species (ROS) pathways, and that both pathways lead to down-regulation of Id-1 expression. Moreover, we demonstrate that CBD up-regulates the pro-differentiation factor, Id-2. Using immune competent mice, we then show that treatment with CBD significantly reduces primary tumor mass as well as the size and number of lung metastatic foci in two models of metastasis. Our data demonstrate the efficacy of CBD in pre-clinical models of breast cancer. The results have the potential to lead to the development of novel non-toxic compounds for the treatment of breast cancer metastasis, and the information gained from these experiments broaden our knowledge of both Id-1 and cannabinoid biology as it pertains to cancer progression.

Sulfation is required for bone morphogenetic protein 2-dependent Id1 induction.

Different reports have suggested the dependence of bone morphogenetic protein (BMP) activity on the sulfated glycosaminoglycan (GAG) chains found in proteoglycans. However, the requirement of sulfated molecules in early BMP-2-signaling responses has not been established. We have used sodium chlorate to inhibit sulfation in C2C12 cells and have analyzed BMP-2 induction of Id1. We show here that sulfation inhibition strongly decreases the specific and early induction of Id1 at the transcriptional level. This effect is not reverted by the addition of extracellular components, such as GAGs or extracellular matrix (ECM). The inhibition of GAG incorporation into proteoglycans, or their removal by GAG lyases, does not mimic the negative effect on Id1 expression, while sulfation inhibition also represses the Id1-induction exerted by a constitutively active form of the BMP receptor, suggesting that BMP-2-mediated Id1 induction has an intracellular requirement for sulfated molecules.