Modulation of Radiation-Induced NADPH Oxidases in Rat's Heart Tissues by Melatonin

Doxorubicin-Induced Cardiac Remodeling: Mechanisms and Mitigation Strategies

BACKGROUND

The therapeutic prowess of doxorubicin in oncology is marred by its cardiotoxic consequences, manifesting as cardiac remodeling. Pathophysiological alterations triggered by doxorubicin include inflammatory cascades, fibrotic tissue deposition, vascular and valvular changes, and finally cardiomyopathy. These multifarious consequences collectively orchestrate the deterioration of cardiac architecture and function.

METHOD

By charting the molecular underpinnings and remedial prospects, this review aspires to contribute a novel perspective using latest publications to the ongoing quest for cardioprotection in cancer therapy.

RESULTS AND DISCUSSION

Experimental analyses demonstrate the pivotal roles of oxidative stress and subsequent necrosis and apoptosis of cardiomyocytes, muscle cells, endothelial cells, and small muscle cells in different parts of the heart. In addition, severe and unusual infiltration of macrophages, mast cells, and neutrophils can amplify oxidative damage and subsequent impacts such as chronic inflammatory responses, vascular and valvular remodeling, and fibrosis. These modifications can render cardiomyopathy, ischemia, heart attack, and other disorders. In an endeavor to counteract these ramifications, a spectrum of emerging adjuvants and strategies are poised to fortify the heart against doxorubicin's deleterious effects.

CONCLUSION

The compendium of mitigation tactics such as innovative pharmacological agents hold the potential to attenuate the cardiotoxic burden.

Melatonin in Chemo/Radiation Therapy; Implications for Normal Tissues Sparing and Tumor Suppression: An Updated Review

Resistance to therapy and the toxicity of normal tissue are the major problems for efficacy associated with chemotherapy and radiotherapy. Drug resistance is responsible for most cases of mortality associated with cancer. Furthermore, their side effects can decrease the quality of life for surviving patients. An enhancement in the tumor response to therapy and alleviation of toxic effects remain unsolved challenges. One of the interesting topics is the administration of agents with low toxicity to protect normal tissues and/or sensitize cancers to chemo/radiotherapy. Melatonin is a natural body hormone that is known as a multitasking molecule. Although it has antioxidant properties, a large number of experiments have uncovered interesting effects of melatonin that can increase the therapeutic efficacy of chemo/radiation therapy. Melatonin can enhance anticancer therapy efficacy through various mechanisms, cells such as the immune system, and modulation of cell cycle and death pathways, tumor suppressor genes, and also through suppression of some drug resistance mediators. However, melatonin may protect normal tissues through the suppression of inflammation, fibrosis, and massive oxidative stress in normal cells and tissues. In this review, we will discuss the distinct effects of melatonin on both tumors and normal tissues. We review how melatonin may enhance radio/chemosensitivity of tumors while protecting normal tissues such as the lung, heart, gastrointestinal system, reproductive system, brain, liver, and kidney.

An Investigation of the Mechanisms of Radiation-Induced Muscle Injury in a Tree Shrew (Tupaia belangeri) Model

Background

Animal models suitable for investigating mechanisms behind radiation-induced muscle injury are lacking. We developed a tree shrew model of such injury and investigated pathological changes and mechanisms.

Methods

Animals were divided into control (n = 5), radiation-induced acute injury (n = 5), and radiation-induced chronic injury (n = 5) groups. Tensor veli palatini (TVP) muscles of acute injury and chronic injury groups were dissected under a microscope at 1 and 24 weeks after radiation therapy, respectively. TVP muscles were stained with HE and Masson to visualize pathological changes. ELISA was performed to measure oxidative injury. RT-qPCR and immunohistochemical staining was performed to measure expression levels of miR-206 and histone deacetylase 4 (HDAC4).

Results

Compared to the control group, acute injury group showed a significant decrease in miR-206 expression (.061 ± .38, P < .05) and a significant increase in HDAC4 expression (37.05 ± 20.68, P < .05). Chronic injury group showed a significant decrease in miR-206 expression (.23 ± .19, P < .05) and a significant increase in HDAC4 expression (9.66 ± 6.12, P < .05).

Discussion

A tree shrew model of radiation-induced muscle injury was established by exposing TVP muscle region to radiation of 20-Gy. Experimental results indicated that injury caused by radiation persisted despite gradual healing of the TVP muscle and miR-206 regulatory pathway plays a key role in regulating radiation-induced muscle injury.