Erlotinib has tumor inhibitory effect in human retinoblastoma cells

The predictive capacity of in vitro preclinical models to evaluate drugs for the treatment of retinoblastoma

Retinoblastoma is a rare childhood cancer of the eye. Of the small number of drugs are used to treat retinoblastoma, all have been repurposed from drugs developed for other conditions. In order to find drugs or drug combinations better suited to the improved treatment of retinoblastoma, reliable predictive models are required, which facilitate the challenging transition from in vitro studies to clinical trials. In this review, the research performed to date on the development of 2D and 3D in vitro models for retinoblastoma is presented. Most of this research was undertaken with a view to better biological understanding of retinoblastoma, and we discuss the potential for these models to be applied to drug screening. Future research directions for streamlined drug discovery are considered and evaluated, and many promising avenues identified.

Drugging Hijacked Kinase Pathways in Pediatric Oncology: Opportunities and Current Scenario

Childhood cancer is considered rare, corresponding to ~3% of all malignant neoplasms in the human population. The World Health Organization (WHO) reports a universal occurrence of more than 15 cases per 100,000 inhabitants around the globe, and despite improvements in diagnosis, treatment and supportive care, one child dies of cancer every 3 min. Consequently, more efficient, selective and affordable therapeutics are still needed in order to improve outcomes and avoid long-term sequelae. Alterations in kinases' functionality is a trademark of cancer and the concept of exploiting them as drug targets has burgeoned in academia and in the pharmaceutical industry of the 21st century. Consequently, an increasing plethora of inhibitors has emerged. In the present study, the expression patterns of a selected group of kinases (including tyrosine receptors, members of the PI3K/AKT/mTOR and MAPK pathways, coordinators of cell cycle progression, and chromosome segregation) and their correlation with clinical outcomes in pediatric solid tumors were accessed through the R2: Genomics Analysis and Visualization Platform and by a thorough search of published literature. To further illustrate the importance of kinase dysregulation in the pathophysiology of pediatric cancer, we analyzed the vulnerability of different cancer cell lines against their inhibition through the Cancer Dependency Map portal, and performed a search for kinase-targeted compounds with approval and clinical applicability through the CanSAR knowledgebase. Finally, we provide a detailed literature review of a considerable set of small molecules that mitigate kinase activity under experimental testing and clinical trials for the treatment of pediatric tumors, while discuss critical challenges that must be overcome before translation into clinical options, including the absence of compounds designed specifically for childhood tumors which often show differential mutational burdens, intrinsic and acquired resistance, lack of selectivity and adverse effects on a growing organism.

Doxazosin and erlotinib have anticancer effects in the endometrial cancer cell and important roles in ERα and Wnt/β-catenin signaling pathways

ERα and Wnt/β-catenin pathways are critical for the progression of most endometrial cancers. We aimed to investigate the cytotoxic and apoptotic effects of tamoxifen and quinazoline derivative drugs of doxazosin and erlotinib, and their roles in ERα and Wnt/β-catenin signaling pathways in human endometrial cancer RL 95-2 cell. 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay and xCELLigence systems were performed to evaluate cytotoxicity. Furthermore, apoptotic induction was tested by Annexin V analysis. Caspase-3 and -9 activity and changes in the mitochondrial membrane potential were evaluated. The level of reactive oxygen species was measured by incubating with dichlorofluorescein diacetate. Protein ratios of p-ERα/ERα, GSK3β/p-GSK3β, and p-β-catenin/β-catenin and expression levels of ESR1, EGFR, c-Myc genes were evaluated to elucidate mechanisms in signaling pathways. We found that the tested drugs showed cytotoxic and apoptotic effects in the cells. Doxazosin significantly reduced ESR1 expression, slightly reduced the p-β-catenin/β-catenin ratio and c-Myc expression. Erlotinib significantly increased c-Myc expression while significantly decreasing the p-β-catenin/β-catenin and p-ERα/ERα ratio, and ESR1 expression. However, we observed that the cells develop resistance to erlotinib over a certain concentration, suggesting that ERα, ESR1, EGFR, and c-Myc may be a new target for overcoming drug resistance in the treatment of endometrial cancer. We also observed that erlotinib and doxazosin play an important role in the ERα signaling pathway and can act as potent inhibitors of PKA and/or tyrosine kinase in the Wnt/β-catenin signaling pathway in RL 95-2 cell. In conclusion, doxazosin and erlotinib may have a possible therapeutic potential in human endometrial cancer.

Regulatory role of transcription factor HBP1 in anticancer efficacy of EGFR inhibitor erlotinib in HNSCC

BACKGROUND

Epidermal growth factor receptor (EGFR) is often hyperactivated in head and neck squamous cell carcinoma (HNSCC); however, its downstream mediators are not fully identified. Here, we investigate the role of transcription factor HBP1 in the anticancer efficacy of EGFR inhibitor erlotinib in HNSCC.

METHODS

The effect of erlotinib and HBP1 on cell proliferation and invasion was examined by flow cytometric analysis and a Matrigel invasion assay, respectively. Oral tumor specimens were used to evaluate the association between the expression level of EGFR and HBP1, and metastatic potential.

RESULTS

Erlotinib caused cell growth arrest in the G1 phase and sluggish invasion with a concomitant increase in HBP1 and p27 expression. The erlotinib effect was attenuated upon HBP1 knockdown. Analysis of oral tumor specimens revealed that the low HBP1/high EGFR status can predict metastatic potential.

CONCLUSIONS

Our data support HBP1 as a crucial mediator of EGFR-targeting inhibitors in HNSCC.

The Role of Intraarterial Chemotherapy in the Management of Retinoblastoma

Introduction. Retinoblastoma is the most common primary intraocular neoplasm in children. With the advances in medicine, the armamentarium of available treatment modalities has grown. Intraarterial chemotherapy is a relatively new treatment method with promising outcomes. The purpose of this literature review is to evaluate its role in the management of retinoblastoma.

Targeting tyrosine kinases for treatment of ocular tumors

Uveal melanoma is the most common intraocular primary malignant tumor in adults, and retinoblastoma is the one in children. Current mainstay treatment options include chemotherapy using conventional drugs and enucleation, the total removal of the eyeball. Targeted therapies based on profound understanding of molecular mechanisms of ocular tumors may increase the possibility of preserving the eyeball and the vision. Tyrosine kinases, which modulate signaling pathways regarding various cellular functions including proliferation, differentiation, and attachment, are one of the attractive targets for targeted therapies against uveal melanoma and retinoblastoma. In this review, the roles of both types of tyrosine kinases, receptor tyrosine kinases and non-receptor tyrosine kinases, were summarized in relation with ocular tumors. Although the conventional treatment options for uveal melanoma and retinoblastoma are radiotherapy and chemotherapy, respectively, specific tyrosine kinase inhibitors will enhance our armamentarium against them by controlling cancer-associated signaling pathways related to tyrosine kinases. This review can be a stepping stone for widening treatment options and realizing targeted therapies against uveal melanoma and retinoblastoma.