Current Cancer Drug Targets - Volume 20, Issue 6, 2020

Lung cancer is the leading cause of cancer-related deaths worldwide. Most lung cancer patients are diagnosed at advanced stages and may benefit from pembrolizumab (anti-PD-1 antibody), cytotoxic chemotherapy and other adjuvant therapies. Despite the availability of various therapies, the response and survival rates have been low. Therefore, the study of different targets for the treatment of lung cancer has been one of the major focuses of cancer research. The ubiquitin proteasome system (UPS) is a crucial regulator of cell homeostasis and plays an essential role in the growth and development of all cells. The UPS is dysregulated in human cancer cells including lung cancer cells. Therefore, targeting UPS is potentially a selective, effective treatment for lung cancer. Bortezomib, a 20S proteasome inhibitor that is clinically approved for the management of multiple myeloma, has been studied in various preclinical and clinical models of lung cancer. Most preclinical studies have shown that a 20S proteasome inhibitor alone and its combination with other chemotherapeutic agents induce apoptosis in non-small cell lung cancer cell lines and animal models. Owing to the impressive preclinical results, many clinical trials were initiated using 20S proteasome inhibitors either as monotherapy or in combination with other conventional lung cancer therapies. Many combinational therapies of 20S PIs with conventional chemotherapy were shown to be well tolerated in clinical trials. However, there have not been any consistent data showing the beneficial effects of such proteasome inhibitor-based therapies. Low clinical efficacy of 20S PIs in lung cancer patients may be due to low drug penetration, the status of 20S proteasomes, oncogene expressions and the inherited or acquired resistance. Potential mechanisms of PI resistance or low or no clinical activity in lung cancer cells might include alteration of apoptotic proteins, overexpression or alteration of β5 subunit, or upregulation of heat shock proteins. Various cutting-edge strategies to counter this resistance or improve 20S PIs’ efficacy in lung cancer cells have been reviewed which include novel combination therapies, new drug delivery systems, development of more potent PIs, and targeting different sites of the UPS. A better understanding of PI resistance mechanisms in lung cancer cells can help improve current clinical treatment strategies and clinical outcomes.

The outbreak of COVID-19 due to SARS-CoV-2 originally emerged in Wuhan in December 2019. As of March 22, 2020, the disease spread to 186 countries, with at least 305,275 confirmed cases. Although there has been a decline in the spread of the disease in China, the prevalence of COVID-19 around the world remains serious despite containment efforts undertaken by national authorities and the international community. In this article, we systematically review the brief history of COVID-19 and its epidemic and clinical characteristics, highlighting the strategies used to control and prevent the disease in China, which may help other countries respond to the outbreak. This pandemic emphasizes the need to be constantly alert to shifts in both the global dynamics and the contexts of individual countries, making sure that all are aware of which approaches are successful for the prevention, containment and treatment of new diseases, and being flexible enough to adapt the responses accordingly.

The mitogen-activated protein kinase (MAPK) pathway is among the key factors in numerous cellular processes involved in tumorigenesis, suggesting it as a potential therapeutic target in gynecological cancer. MAPKs connect gene expression pathways and external stimulations. They include a network consisting of Ras, Raf or MAP3K, MEK or MAP2K, ERK or MAPK. Among these, MEK is an attractive molecular target of novel cancer therapeutics as it joints upstream activators and their corresponding downstream targets. MEK inhibitors were among the first inhibitors of the MAPK pathway entering into clinical trials. Several drugs have recently been developed as MEK inhibitors. MEK1/2 inhibitors demonstrate promising efficacy and anticancer activity to treat this malignancy and captured much attention in the past decade. Here, we summarize the role of MAPK/MEK/ERK pathway in the pathogenesis of gynecological cancer, with particular emphasis on MEK inhibitors in clinical settings, including PD-0325901, Selumetinib, Cobimetinib, Refametinib, Trametinib, Pimasertib, MEK162 and WX-554 in gynecologic cancers.

During the last century, our battle against cancer has been inaugurated upon three main approaches; surgery, radiation and chemotherapy. The latest findings on the effectiveness of immunotherapy in cancer management offer a ray of hope after decades of research and studies on the best treatment methods. Immunotherapy has proven effective in the surveillance and destruction of cancer- causing cells, demonstrating its ability to suppress cancer through controlling the wellestablished immune-editing process. Immuno-editing is a process that comprises three principal elements; elimination, equilibrium, and escape, and is paramount to the comprehension of checkpoint inhibition. Cancer cells employ various approaches to evade the elimination step leading to its immune- escape. The escape mechanism encompasses the up-regulation of negative co-signals that block successful activation of cancer-eradicating immune cells, developing cytokine background that favors the immunosuppressive tumor microenvironment (TME), or dropping the expression of tumor- specific proteins known as neo-antigens, therefore reducing the immunogenic activity against cancer cells. Today, checkpoint inhibitors are considered as a primary approach in our fight against cancer. Strategies targeting the inhibitory roles of checkpoint inhibitors have been shown effective against different cancer types and stages, and some already gained the FDA’s approval. This review seeks to comprehensively cover the historical background as well as the most recent updates for the role of immune checkpoint regulators in the maintenance of immune homeostatic balance as well as keeping the tumorigenic cells in check.

Background: Emerging studies have indicated that circular RNAs (circRNAs) play important roles in the development of many tumors. CircRNA-scavenger receptor class B member 1 (Circ-SCARB1) was consistently reported as an elevated circRNA in RCC tissues. This study focused on examining the biological function and molecular mechanism of circSCARB1 in RCC progression. Methods: Expressions of Circ-SCARB1, microRNA (miR)-510-5p, and syndecan 3 (SDC3) were detected using a quantitative real-time polymerase chain reaction (RT-PCR) and/or western blot. Cell proliferation and apoptosis were measured by 3-(4, 5)-dimethylthiahiazo (-z-y1)-3, 5-diphenytetrazoliumromide and flow cytometry, respectively. Cell migration and invasion were measured using Transwell assays. The interaction between miR-510-5p and Circ-SCARB1 or SDC3 was verified using dual-luciferase reporter assays. Results: Circ-SCARB1 was elevated in 30 pairs of RCC tissues and multiple RCC cell lines. Knockdown of Circ-SCARB1 inhibited cell proliferation, migration, and invasion while inducing cell apoptosis. MiR-510-5p was confirmed to be a target of Circ-SCARB1; inhibition of cell progression by silencing Circ-SCARB1 was mediated by a direct interaction between Circ-SCARB1 and miR-510-5p. SDC3 was verified to be a gene target of miR-510-5p; transfection of miR-510-5p mimic not only suppressed the expression of SDC3 but also the cell proliferation and an SDC3 cotransfection partially restored cell proliferation. Additionally, the genetic knockdown of Circ- SCARB1 reduced the expression SDC3, and the addition of anti-miR-510-5p could partially reelevate SDC3 expression. Conclusion: Circ-SCARB1 promotes RCC progression via sequestering miR-510-5p and indirectly up-regulating SDC3 expression. This provides a novel perspective for the pathogenesis of RCC and potential therapeutic targets for the treatment of RCC.