Tumor Microenvironment-Responsive, Multistaged Liposome Induces Apoptosis and Ferroptosis by Amplifying Oxidative Stress for Enhanced Cancer Therapy

: Elevated Reactive Oxygen Species (ROS) generated by the conventional cancer therapies and the endogenous production of ROS have been observed in various types of cancers. In contrast to the harmful effects of oxidative stress in different pathologies other than cancer, ROS can speed anti-tumorigenic signaling and cause apoptosis of tumor cells via oxidative stress as demonstrated in several studies. The primary actions of antioxidants in cells are to provide a redox balance between reduction-oxidation reactions. Antioxidants in tumor cells can scavenge excess ROS, causing resistance to ROS induced apoptosis. Various chemotherapeutic drugs, in their clinical use, have evoked drug resistance and serious side effects. Consequently, drugs having single-targets are not able to provide an effective cancer therapy. Recently, developed hybrid anticancer drugs promise great therapeutic advantages due to their capacity to overcome the limitations encountered with conventional chemotherapeutic agents. Hybrid compounds have advantages in comparison to the single cancer drugs which have usually low solubility, adverse side effects, and drug resistance. This review addresses two important treatments strategies in cancer therapy: oxidative stress induced apoptosis and hybrid anticancer drugs.

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Oxidative Stress in the Tumor Microenvironment and Its Relevance to Cancer Immunotherapy

Cancers ◽

10.3390/cancers13050986 ◽

2021 ◽

Vol 13 (5) ◽

pp. 986

Author(s):

Nada S. Aboelella ◽

Caitlin Brandle ◽

Timothy Kim ◽

Zhi-Chun Ding ◽

Gang Zhou

Keyword(s):

Oxidative Stress ◽

Tumor Microenvironment ◽

Cancer Cells ◽

Redox Homeostasis ◽

Tumor Rejection ◽

Oxygen Species ◽

Antitumor Effects ◽

Key Drivers ◽

Cancer Immunotherapies ◽

The Impact

It has been well-established that cancer cells are under constant oxidative stress, as reflected by elevated basal level of reactive oxygen species (ROS), due to increased metabolism driven by aberrant cell growth. Cancer cells can adapt to maintain redox homeostasis through a variety of mechanisms. The prevalent perception about ROS is that they are one of the key drivers promoting tumor initiation, progression, metastasis, and drug resistance. Based on this notion, numerous antioxidants that aim to mitigate tumor oxidative stress have been tested for cancer prevention or treatment, although the effectiveness of this strategy has yet to be established. In recent years, it has been increasingly appreciated that ROS have a complex, multifaceted role in the tumor microenvironment (TME), and that tumor redox can be targeted to amplify oxidative stress inside the tumor to cause tumor destruction. Accumulating evidence indicates that cancer immunotherapies can alter tumor redox to intensify tumor oxidative stress, resulting in ROS-dependent tumor rejection. Herein we review the recent progresses regarding the impact of ROS on cancer cells and various immune cells in the TME, and discuss the emerging ROS-modulating strategies that can be used in combination with cancer immunotherapies to achieve enhanced antitumor effects.

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Targeting the Ubiquitin Signaling Cascade in Tumor Microenvironment for Cancer Therapy

International Journal of Molecular Sciences ◽

10.3390/ijms22020791 ◽

2021 ◽

Vol 22 (2) ◽

pp. 791

Author(s):

Qi Liu ◽

Bayonle Aminu ◽

Olivia Roscow ◽

Wei Zhang

Keyword(s):

Tumor Microenvironment ◽

Cancer Therapy ◽

Therapeutic Agents ◽

Biological Processes ◽

Post Translational Modification ◽

E3 Ligases ◽

Tumor Microenvironments ◽

Cellular Immune ◽

Ubiquitin Conjugating Enzymes ◽

Cellular Components

Tumor microenvironments are composed of a myriad of elements, both cellular (immune cells, cancer-associated fibroblasts, mesenchymal stem cells, etc.) and non-cellular (extracellular matrix, cytokines, growth factors, etc.), which collectively provide a permissive environment enabling tumor progression. In this review, we focused on the regulation of tumor microenvironment through ubiquitination. Ubiquitination is a reversible protein post-translational modification that regulates various key biological processes, whereby ubiquitin is attached to substrates through a catalytic cascade coordinated by multiple enzymes, including E1 ubiquitin-activating enzymes, E2 ubiquitin-conjugating enzymes and E3 ubiquitin ligases. In contrast, ubiquitin can be removed by deubiquitinases in the process of deubiquitination. Here, we discuss the roles of E3 ligases and deubiquitinases as modulators of both cellular and non-cellular components in tumor microenvironment, providing potential therapeutic targets for cancer therapy. Finally, we introduced several emerging technologies that can be utilized to develop effective therapeutic agents for targeting tumor microenvironment.

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