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Carcinogenic effects of circadian disruption: an epigenetic viewpoint.

Salavaty A - Chin J Cancer (2015)

Bottom Line: Circadian regulatory pathways result in rhythmic epigenetic modifications and the formation of circadian epigenomes.Several studies have indicated an epigenetic basis for the carcinogenic effects of circadian disruption.Then, I summarize the current evidence related to the epigenetic modifications that result in circadian disruption.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, 61336-3337, Ahvaz, Iran. abbas.salavaty@gmail.com.

ABSTRACT
Circadian rhythms refer to the endogenous rhythms that are generated to synchronize physiology and behavior with 24-h environmental cues. These rhythms are regulated by both external cues and molecular clock mechanisms in almost all cells. Disruption of circadian rhythms, which is called circadian disruption, affects many biological processes within the body and results in different long-term diseases, including cancer. Circadian regulatory pathways result in rhythmic epigenetic modifications and the formation of circadian epigenomes. Aberrant epigenetic modifications, such as hypermethylation, due to circadian disruption may be involved in the transformation of normal cells into cancer cells. Several studies have indicated an epigenetic basis for the carcinogenic effects of circadian disruption. In this review, I first discuss some of the circadian genes and regulatory proteins. Then, I summarize the current evidence related to the epigenetic modifications that result in circadian disruption. In addition, I explain the carcinogenic effects of circadian disruption and highlight its potential role in different human cancers using an epigenetic viewpoint. Finally, the importance of chronotherapy in cancer treatment is highlighted.

No MeSH data available.


Related in: MedlinePlus

Different circadian disruptive factors that lead to cancer. Circadian rhythms are disrupted in a variety of ways. Several environmental factors, such as night-shift work, exposure to artificial light, and exposure to electromagnetic (EM) waves, result in circadian disruption mostly by altering melatonin rhythms. Irregular diet may also lead to circadian disruption. Moreover, impaired circadian gene expression, due to mutation or epigenetic factors, also results in circadian disruption. Disrupted circadian rhythms both directly and indirectly lead to aberrant epigenetic modifications that result in cell proliferation and cancer.
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Fig2: Different circadian disruptive factors that lead to cancer. Circadian rhythms are disrupted in a variety of ways. Several environmental factors, such as night-shift work, exposure to artificial light, and exposure to electromagnetic (EM) waves, result in circadian disruption mostly by altering melatonin rhythms. Irregular diet may also lead to circadian disruption. Moreover, impaired circadian gene expression, due to mutation or epigenetic factors, also results in circadian disruption. Disrupted circadian rhythms both directly and indirectly lead to aberrant epigenetic modifications that result in cell proliferation and cancer.

Mentions: Circadian disruption has been implicated in the development of different human cancers (Table 1). Disruption of circadian rhythms leads to epigenetic modifications, which may alter cell proliferation and subsequently result in oncogenesis and cancer [22] (Fig. 2). For example, disruption of melatonin rhythms is related to carcinogenesis. Many of these circadian disruptions are due to dramatic changes resulting from industrialization and the development of societies and consequent changes in lifestyle over the past few hundred years [12]. Epigenetic changes can be the result of several environmental factors, including repeated circadian disruption due to long-term shift work. Studies on shift workers have demonstrated changes in the DNA methylation of their genes [22]. It has been reported that 15%–20% of workers have shift work schedules worldwide. In 2007, the International Agency for Research on Cancer (IARC) reported that shift work may be a carcinogenic factor in humans [28]. In addition, studies of breast cancer in women with shift work schedules have provided more evidence for the carcinogenic effects of circadian disruption [29].Table 1


Carcinogenic effects of circadian disruption: an epigenetic viewpoint.

Salavaty A - Chin J Cancer (2015)

Different circadian disruptive factors that lead to cancer. Circadian rhythms are disrupted in a variety of ways. Several environmental factors, such as night-shift work, exposure to artificial light, and exposure to electromagnetic (EM) waves, result in circadian disruption mostly by altering melatonin rhythms. Irregular diet may also lead to circadian disruption. Moreover, impaired circadian gene expression, due to mutation or epigenetic factors, also results in circadian disruption. Disrupted circadian rhythms both directly and indirectly lead to aberrant epigenetic modifications that result in cell proliferation and cancer.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4593354&req=5

Fig2: Different circadian disruptive factors that lead to cancer. Circadian rhythms are disrupted in a variety of ways. Several environmental factors, such as night-shift work, exposure to artificial light, and exposure to electromagnetic (EM) waves, result in circadian disruption mostly by altering melatonin rhythms. Irregular diet may also lead to circadian disruption. Moreover, impaired circadian gene expression, due to mutation or epigenetic factors, also results in circadian disruption. Disrupted circadian rhythms both directly and indirectly lead to aberrant epigenetic modifications that result in cell proliferation and cancer.
Mentions: Circadian disruption has been implicated in the development of different human cancers (Table 1). Disruption of circadian rhythms leads to epigenetic modifications, which may alter cell proliferation and subsequently result in oncogenesis and cancer [22] (Fig. 2). For example, disruption of melatonin rhythms is related to carcinogenesis. Many of these circadian disruptions are due to dramatic changes resulting from industrialization and the development of societies and consequent changes in lifestyle over the past few hundred years [12]. Epigenetic changes can be the result of several environmental factors, including repeated circadian disruption due to long-term shift work. Studies on shift workers have demonstrated changes in the DNA methylation of their genes [22]. It has been reported that 15%–20% of workers have shift work schedules worldwide. In 2007, the International Agency for Research on Cancer (IARC) reported that shift work may be a carcinogenic factor in humans [28]. In addition, studies of breast cancer in women with shift work schedules have provided more evidence for the carcinogenic effects of circadian disruption [29].Table 1

Bottom Line: Circadian regulatory pathways result in rhythmic epigenetic modifications and the formation of circadian epigenomes.Several studies have indicated an epigenetic basis for the carcinogenic effects of circadian disruption.Then, I summarize the current evidence related to the epigenetic modifications that result in circadian disruption.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, 61336-3337, Ahvaz, Iran. abbas.salavaty@gmail.com.

ABSTRACT
Circadian rhythms refer to the endogenous rhythms that are generated to synchronize physiology and behavior with 24-h environmental cues. These rhythms are regulated by both external cues and molecular clock mechanisms in almost all cells. Disruption of circadian rhythms, which is called circadian disruption, affects many biological processes within the body and results in different long-term diseases, including cancer. Circadian regulatory pathways result in rhythmic epigenetic modifications and the formation of circadian epigenomes. Aberrant epigenetic modifications, such as hypermethylation, due to circadian disruption may be involved in the transformation of normal cells into cancer cells. Several studies have indicated an epigenetic basis for the carcinogenic effects of circadian disruption. In this review, I first discuss some of the circadian genes and regulatory proteins. Then, I summarize the current evidence related to the epigenetic modifications that result in circadian disruption. In addition, I explain the carcinogenic effects of circadian disruption and highlight its potential role in different human cancers using an epigenetic viewpoint. Finally, the importance of chronotherapy in cancer treatment is highlighted.

No MeSH data available.


Related in: MedlinePlus