Retinoblastoma: present scenario and future challenges.

With an average incidence of 1 in every 18,000 live births, retinoblastoma is a rare type of intraocular tumour found to affect patients during their early childhood. It is curable if diagnosed at earlier stages but can become life-threateningly malignant if not treated timely. With no racial or gender predisposition, or even environmental factors known to have been involved in the incidence of the disease, retinoblastoma is often considered a clinical success story in pediatric oncology. The survival rate in highly developed countries is higher than 95% and they have achieved this because of the advancement in the development of diagnostics and treatment techniques. This includes developing the already existing techniques like chemotherapy and embarking on new strategies like enucleation, thermotherapy, cryotherapy, etc. Early diagnosis, studies on the etiopathogenesis and genetics of the disease are the need of the hour for improving the survival rates. According to the Knudson hypothesis, also known as the two hit hypothesis, two hits on the retinoblastoma susceptibility (RB) gene is often considered as the initiating event in the development of the disease. Studies on the molecular basis of the disease have also led to deciphering the downstream events and thus in the discovery of biomarkers and related targeted therapies. Furthermore, improvements in molecular biology techniques enhanced the development of efficient methods for early diagnosis, genetic counseling, and prevention of the disease. In this review, we discuss the genetic and molecular features of retinoblastoma with a special emphasis on the mutation leading to the dysregulation of key signaling pathways involved in cell proliferation, DNA repair, and cellular plasticity. Also, we describe the classification, clinical and epidemiological relevance of the disease, with an emphasis on both the traditional and innovative treatments to tackle retinoblastoma. Video Abstract.

Dual modulation of Ras-Mnk and PI3K-AKT-mTOR pathways: A Novel c-FLIP inhibitory mechanism of 3-AWA mediated translational attenuation through dephosphorylation of eIF4E.

The eukaryotic translation initiation factor 4E (eIF4E) is considered as a key survival protein involved in cell cycle progression, transformation and apoptosis resistance. Herein, we demonstrate that medicinal plant derivative 3-AWA (from Withaferin A) suppressed the proliferation and metastasis of CaP cells through abrogation of eIF4E activation and expression via c-FLIP dependent mechanism. This translational attenuation prevents the de novo synthesis of major players of metastatic cascades viz. c-FLIP, c-Myc and cyclin D1. Moreover, the suppression of c-FLIP due to inhibition of translation initiation complex by 3-AWA enhanced FAS trafficking, BID and caspase 8 cleavage. Further ectopically restored c-Myc and GFP-HRas mediated activation of eIF4E was reduced by 3-AWA in transformed NIH3T3 cells. Detailed underlying mechanisms revealed that 3-AWA inhibited Ras-Mnk and PI3-AKT-mTOR, two major pathways through which eIF4E converges upon eIF4F hub. In addition to in vitro studies, we confirmed that 3-AWA efficiently suppressed tumor growth and metastasis in different mouse models. Given that 3-AWA inhibits c-FLIP through abrogation of translation initiation by co-targeting mTOR and Mnk-eIF4E, it (3-AWA) can be exploited as a lead pharmacophore for promising anti-cancer therapeutic development.

Par-4 dependent modulation of cellular ß-catenin by medicinal plant natural product derivative 3-azido Withaferin A.

Here, we provide evidences that natural product derivative 3-azido Withaferin A (3-AWA) abrogated EMT and invasion by modulating ß-catenin localization and its transcriptional activity in the prostate as well as in breast cancer cells. This study, for the first time, reveals 3-AWA treatment consistently sequestered nuclear ß-catenin and augmented its cytoplasmic pool as evidenced by reducing ß-catenin transcriptional activity in these cells. Moreover, 3-AWA treatment triggered robust induction of pro-apoptotic intracellular Par-4, attenuated Akt activity and rescued Phospho-GSK3ß (by Akt) to promote ß-catenin destabilization. Further, our in vitro studies demonstrate that 3-AWA treatment amplified E-cadherin expression along with sharp downregulation of c-Myc and cyclin D1 proteins. Strikingly, endogenous Par-4 knock down by siRNA underscored 3-AWA mediated inhibition of nuclear ß-catenin was Par-4 dependent and suppression of Par-4 activity, either by Bcl-2 or by Ras transfection, restored the nuclear ß-catenin level suggesting Par-4 mediated ß-catenin regulation was not promiscuous. In vivo results further demonstrated that 3-AWA was effective inhibitor of tumor growth and immunohistochemical studies indicated that increased expression of total ß-catenin and decreased expression of phospho-ß-catenin and Par-4 in breast cancer tissues as compared to normal breast tissue suggesting Par-4 and ß-catenin proteins are mutually regulated and inversely co-related in normal as well as cancer condition. Thus, strategic regulation of intracellular Par-4 by 3-AWA in diverse cancers could be an effective tool to control cancer cell metastasis. Conclusively, this report puts forward a novel approach of controlling deregulated ß-catenin signaling by 3-AWA induced Par-4 protein.