Namrata Rastogi

Inhibition of STAT3, FAK and Src mediated signaling reduces cancer stem cell load, tumorigenic potential and metastasis in breast cancer

Cancer stem cells (CSCs) are responsible for aggressive tumor growth, metastasis and therapy resistance. In this study, we evaluated the effects of Shikonin (Shk) on breast cancer and found its anti-CSC potential. Shk treatment decreased the expression of various epithelial to mesenchymal transition (EMT) and CSC associated markers. Kinase profiling array and western blot analysis indicated that Shk inhibits STAT3, FAK and Src activation. Inhibition of these signaling proteins using standard inhibitors revealed that STAT3 inhibition affected CSCs properties more significantly than FAK or Src inhibition. We observed a significant decrease in cell migration upon FAK and Src inhibition and decrease in invasion upon inhibition of STAT3, FAK and Src. Combined inhibition of STAT3 with Src or FAK reduced the mammosphere formation, migration and invasion more significantly than the individual inhibitions. These observations indicated that the anti-breast cancer properties of Shk are due to its potential to inhibit multiple signaling proteins. Shk also reduced the activation and expression of STAT3, FAK and Src in vivo and reduced tumorigenicity, growth and metastasis of 4T1 cells. Collectively, this study underscores the translational relevance of using a single inhibitor (Shk) for compromising multiple tumor-associated signaling pathways to check cancer metastasis and stem cell load.

Therapeutic targeting of cancer cell cycle using proteasome inhibitors

Proteasomes are multicatalytic protease complexes in the cell, involved in the non-lysosomal recycling of intra-cellular proteins. Proteasomes play a critical role in regulation of cell division in both normal as well as cancer cells. In cancer cells this homeostatic function is deregulated leading to the hyperactivation of the proteasomes. Proteasome inhibitors (PIs) are a class of compounds, which either reversibly or irreversibly block the activity of proteasomes and induce cancer cell death. Interference of PIs with the ubiquitin proteasome pathway (UPP) involved in protein turnover in the cell leads to the accumulation of proteins engaged in cell cycle progression, which ultimately put a halt to cancer cell division and induce apoptosis. Upregulation of many tumor suppressor proteins involved in cell cycle arrest are known to play a role in PI induced cell cycle arrest in a variety of cancer cells. Although many PIs target the proteasomes, not all of them are effective in cancer therapy. Some cancers develop resistance against proteasome inhibition by possibly activating compensatory signaling pathways. However, the details of the activation of these pathways and their contribution to resistance to PI therapy remain obscure. Delineation of these pathways may help in checking resistance against PIs and deducing effective combinational approaches for improved treatment strategies. This review will discuss some of the signaling pathways related to proteasome inhibition and cell division that may help explain the basis of resistance of some cancers to proteasome inhibitors and underline the need for usage of PIs in combination with traditional chemotherapy.

(6)-Gingerolinduced myeloid leukemia cell death is initiated by reactive oxygen species and activation of miR-27b expression

The natural polyphenolic alkanone (6)-gingerol (6G) has established anti-inflammatory and antitumoral properties. However, its precise mechanism of action in myeloid leukemia cells is unclear. In this study, we investigated the effects of 6G on myeloid leukemia cells in vitro and in vivo. The results of this study showed that 6G inhibited proliferation of myeloid leukemia cell lines and primary myeloid leukemia cells while sparing the normal peripheral blood mononuclear cells, in a concentration- and time-dependent manner. Mechanistic studies using U937 and K562 cell lines revealed that 6G treatment induced reactive oxygen species (ROS) generation by inhibiting mitochondrial respiratory complex I (MRC I), which in turn increased the expression of the oxidative stress response-associated microRNA miR-27b and DNA damage. Elevated miR-27b expression inhibited PPARγ, with subsequent inhibition of the inflammatory cytokine gene expression associated with the oncogenic NF-κB pathway, whereas the increased DNA damage led to G2/M cell cycle arrest. The 6G induced effects were abolished in the presence of anti-miR-27b or the ROS scavenger N-acetylcysteine. In addition, the results of the in vivo xenograft experiments in mice indicated that 6G treatment inhibited tumor cell proliferation and induced apoptosis, in agreement with the in vitro studies. Our data provide new evidence that 6G-induced myeloid leukemia cell death is initiated by reactive oxygen species and mediated through an increase in miR-27b expression and DNA damage. The dual induction of increased miR-27b expression and DNA damage-associated cell cycle arrest by 6G may have implications for myeloid leukemia treatment.

Attenuated neuroprotective effect of riboflavin under UV-B irradiation via miR-203/c-Jun signaling pathway in vivo and in vitro.

BackgroundRiboflavin (RF) or vitamin B2 is known to have neuroprotective effects. In the present study, we report the attenuation of the neuroprotective effects of RF under UV-B irradiation. Preconditioning of UV-B irradiated riboflavin (UV-B-RF) showed attenuated neuroprotective effects compared to that of RF in SH-SY5Y neuroblostoma cell line and primary cortical neurons in vitro and a rat model of cerebral ischemia in vivo.ResultsResults indicated that RF pretreatment significantly inhibited cell death and reduced LDH secretion compared to that of the UV-B-RF pretreatment in primary cortical neuron cultures subjected to oxygen glucose deprivation in vitro and cortical brain tissue subjected to ischemic injury in vivo. Further mechanistic studies using cortical neuron cultures revealed that RF treatment induced increased miR-203 expression which in turn inhibited c-Jun expression and increased neuronal cell survival. Functional assays clearly demonstrated that the UV-B-RF preconditioning failed to sustain the increased expression of miR-203 and the decreased levels of c-Jun, mediating the neuroprotective effects of RF. UV-B irradiation attenuated the neuroprotective effects of RF through modulation of the miR-203/c-Jun signaling pathway.ConclusionThus, the ability of UV-B to serve as a modulator of this neuroprotective signaling pathway warrants further studies into its role as a regulator of other cytoprotective/neuroprotective signaling pathways.

Proteasome inhibition mediates p53 reactivation and anti-cancer activity of 6-Gingerol in cervical cancer cells

Human papilloma virus (HPV) expressing E6 and E7 oncoproteins, is known to inactivate the tumor suppressor p53 through proteasomal degradation in cervical cancers. Therefore, use of small molecules for inhibition of proteasome function and induction of p53 reactivation is a promising strategy for induction of apoptosis in cervical cancer cells. The polyphenolic alkanone, 6-Gingerol (6G), present in the pungent extracts of ginger (Zingiber officinale Roscoe) has shown potent anti-tumorigenic and pro-apoptotic activities against a variety of cancers. In this study we explored the molecular mechanism of action of 6G in human cervical cancer cells in vitro and in vivo. 6G potently inhibited proliferation of the HPV positive cervical cancer cells. 6G was found to: (i) inhibit the chymotrypsin activity of proteasomes, (ii) induce reactivation of p53, (iii) increase levels of p21, (iv) induce DNA damage and G2/M cell cycle arrest, (v) alter expression levels of p53-associated apoptotic markers like, cleaved caspase-3 and PARP, and (vi) potentiate the cytotoxicity of cisplatin. 6G treatment induced significant reduction of tumor volume, tumor weight, proteasome inhibition and p53 accumulation in HeLa xenograft tumor cells in vivo. The 6G treatment was devoid of toxic effects as it did not affect body weights, hematological and osteogenic parameters. Taken together, our data underscores the therapeutic and chemosensitizing effects of 6G in the management and treatment of cervical cancer.

Identification of Novel 2-((1-(Benzyl(2-hydroxy-2-phenylethyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamoyl)benzoic Acid Analogues as BMP-2 Stimulators

The synthesis and SAR studies of 10 new chemical entities (NCEs) that have shown BMP-2 stimulation and osteoblast differentiation are reported. Among these, 2-((1-(benzyl(2-hydroxy-2-phenylethyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamoyl)benzoic acid (11) was the most effective while its analogue 13 also showed good activity in inducing osteoblast BMP-2 production. Compound 11 induced osteoblast differentiation in vitro, and this effect was abrogated by a physiological BMP-2 inhibitor, noggin. It also exhibited dose dependent increase in nascent bone formation (2.16- and 3.12-fold more than the control at 1 and 5 mg/kg dose, respectively) at the fracture site in rats. At the maximum osteogenic concentration, compound 11 significantly inhibited osteoblastic proteosomal activity. This compound was safe, as it had no effect on BMP synthesis in cardiovascular tissue.

Unsaturated Phosphonates as Hauser Acceptors for the Synthesis of Phosphonylated Dihydroxynaphthalenes and Naphthoquinones.

The unsaturated phosphonates were utilized as Hauser acceptors successfully for the first time. The products phosphonylated 1,4-dihydroxynaphthalenes were isolated in good yields in short reaction time and were further oxidized to the corresponding 1,4-naphthoquinones in quantitative yields. The reaction provides an efficient and straightforward approach for the synthesis of pharmacologically privileged disubstituted naphthalene-1,4-diols and naphtha-1,4-diones bearing a phosphonate group at the 2-position and various (het)aryl groups at the 3-position.

Serum Vascular Endothelial Growth Factor-A (VEGF-A) as a Biomarker in Squamous Cell Carcinoma of Head and Neck Patients Undergoing Chemoradiotherapy

BACKGROUND To evaluate serum VEGF-A levels in squamous cell carcinoma of head and neck (SCCHN) patients and relationships with response to therapy. MATERIALS AND METHODS Serum VEGF-A levels in patients (n=72) treated with radiotherapy (RT) or radio-chemotherapy (RCT) and controls (n=40) were measured by ELISA. RESULTS Serum VEGF-A levels of the SCCHN cases were significantly higher (p=0.001) than in healthy controls, and in patients with positive as compared to negative lymph node status (p=0.004). Similarly, patients with advanced stage (Stage III-IV) disease had more greatly elevated levels of serum VEGF-A level than their early stage (Stage I-II) counterparts (p=0.001). In contrast, there was no significant difference (p=0.57) in serum level of VEGF-A in patients with advanced T-stage (T3-4) as compared to early stage (T1-2). Similarly, patients with distant metastasis had no significant (p=0.067) elevation in serum VEGF-A level as compared to non-metastatic disease. However, the non-responder patients had significantly higher serum VEGF-A level as compared to responders (p=0.001). CONCLUSIONS Our results suggest that the serum VEGF-A level may be a useful biomarker for the prediction of response to therapy in SCCHN.

Evaluation of miR-711 as Novel Biomarker in Prostate Cancer Progression

Objective: MicroRNAs (miRs) are class of small non-coding regulatory RNA aberrantly expressed in various types of malignancies including prostate cancer and serves as potential targets to develop new diagnostic and therapeutic strategies. In this quiet we investigated miRNAs expression profile in benign prostatic hyperplasia (BPH) and prostate cancer (PCa) tissue samples and correlated their expression with clinicopathological parameters. Methodology: The miRNAs expression profile as well as their validation has been done by using Microarray and RT-PCR, respectively. Additionally, we also tried to speculate microRNA-mRNA regulatory module through computational target predictions by using Targetscan, Miranda and MirWalk and obtained results were analysed through DAVID software. Result: We observed that miR-711 is significantly deregulated in BPH and PCa, compared to controls. The lower expression of miR-711 was found to be significantly associated with high Gleason score and metastatic disease. Furthermore, the computational target prediction analysis explored miR-711 association to various cancer cells signalling cascade key molecules associated with cancer cell survival. Conclusion: From our observations we suggest that miR-711 may play a critical role in PCa progression, regulation of various cancer cell survival signalling cascades and that it may be a valuable biomarker for prediction of metastatic disease and poor prognosis in PCa.

Visible light catalyzed synthesis of quinolines from (aza)-Morita–Baylis–Hillman adducts

A mild and efficient protocol for the synthesis of quinoline scaffolds from (aza)-MBH adducts under visible light catalysis has been established. The reaction involves visible light catalyzed generation of amidyl radicals from (aza)-MBH adducts followed by intramolecular radical cyclization. The reaction exhibits a wide substrate scope, good functional group tolerance and high regioselectivity. This is the first example of utilizing (aza)-MBH adducts for the generation of amidyl radicals and synthesizing aza-heterocycles under visible light photoredox catalyzed reaction conditions.