Novel benzoxazines as inhibitors of angiogenesis

Role of Small Molecule Targeted Compounds in Cancer: Progress, Opportunities, and Challenges

Research on molecular targeted therapy of tumors is booming, and novel targeted therapy drugs are constantly emerging. Small molecule targeted compounds, novel targeted therapy drugs, can be administered orally as tablets among other methods, and do not draw upon genes, causing no immune response. It is easily structurally modified to make it more applicable to clinical needs, and convenient to promote due to low cost. It refers to a hotspot in the research of tumor molecular targeted therapy. In the present study, we review the current Food and Drug Administration (FDA)-approved use of small molecule targeted compounds in tumors, summarize the clinical drug resistance problems and mechanisms facing the use of small molecule targeted compounds, and predict the future directions of the evolving field.

Angiogenesis inhibitors as therapeutic agents in cancer: Challenges and future directions

Angiogenesis has become an attractive target for cancer therapy since the US Food and Drug Administration (FDA) approved the first angiogenesis inhibitor (bevacizumab) for the treatment of metastatic colorectal cancer in 2004. In following years, a large number of angiogenesis inhibitors have been discovered and developed, ranging from monoclonal antibodies, endogenous peptides, to small organic molecules and microRNAs. Many of them are now entering the clinical trial, or achieving approval for clinical use. However, major limitations have been observed about angiogenesis inhibitors by continued clinical investigations, such as resistance, enhancing tumor hypoxia and reducing delivery of chemotherapeutic agents, which might be the main reason for poor improvement in overall survival after angiogenesis inhibitor administration in clinic. Therefore, optimal anti-angiogenic therapy strategies become critical. The present review summarizes recent researches in angiogenesis inhibitors, and proposes a perspective on future directions in this field.

Endostatin combined with radiotherapy suppresses vasculogenic mimicry formation through inhibition of epithelial-mesenchymal transition in esophageal cancer

The growth of solid tumors requires angiogenesis to provide oxygen and nutrients and to support cell proliferation. The switch from an avascular to a vascular phenotype is typically related to acceleration of tumor growth. Anti-angiogenic therapy is becoming a very promising way for malignant tumors. Meanwhile, malignant tumor cells themselves were able to develop the formation of cell-lined vessels that contribute to tumor neovascularization and supply the nutrients and oxygen, which is called vasculogenic mimicry (VM). However, the molecular mechanism of VM remains unclear. The purpose of this study was to investigate the efficacy of the novel recombinant human endostatin (rh-Endo) protein combined with radiotherapy on human esophageal squamous cell carcinoma (ESCC) cell lines Eca-109 and TE13. Our results showed that rh-Endo combined with radiotherapy significantly inhibited the proliferation, migration, invasion, and VM of human esophageal cancer cells in a dose-dependent manner; however, it has no direct effect on apoptosis of carcinoma cells, which indicated that rh-Endo combined with radiotherapy significantly changed the microenvironment of esophageal carcinoma, and played an important role in preventing distant metastasis. Our findings suggested that rh-Endo inhibited the metastasis of esophageal cancer and the activation of AKT pathway, and the down-regulation of epithelial-mesenchymal transition (EMT) may be associated with such effect of rh-Endo. These results also supported the bright prospect of rh-Endo combined with radiotherapy for clinical applications in the future.

Recombinant human endostatin enhances the radioresponse in esophageal squamous cell carcinoma by normalizing tumor vasculature and reducing hypoxia

The aim of this study was to investigate the effect of recombinant human endostatin (rh-Endo) in combination with radiation therapy (RT) on esophageal squamous cell carcinoma (ESCC) and explore the potential mechanisms. ECA109-bearing nude mice were administered RT and/or rh-Endo treatment. Tumor volume, survival, hypoxia and vascular parameters were recorded during the treatment schedule and follow-up as measures of treatment response. ESCC cell lines (ECA109 and TE13) and human umbilical vein endothelial cells (HUVECs) were developed to investigate the outcomes and toxicities of rh-Endo and RT in vitro. Hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were also evaluated. In vivo studies of ECA109-bearing xenografts showed that rh-Endo improved the radioresponse, with normalization of tumor vasculature and a reduction in hypoxia. In vitro studies showed that rh-Endo did not radiosensitize ESCC cell lines but did affect endothelial cells with a time- and dose-dependent manner. Studies of the molecular mechanism indicated that the improved radioresponse might be due to crosstalk between cancer cells and endothelial cells involving HIF and VEGF expression. Our data suggest that rh-Endo may be a potential anti-angiogenic agent in ESCC especially when combined with RT. The improved radioresponse arises from normalization of tumor vasculature and a reduction in hypoxia.