The role of circadian gene timeless in gastrointestinal cancers
sohrab minaei beirami,1,*Kamran Hosseini,2Haleh Forouhandeh,3Sepideh Zununi Vahed,4Shirin Eyvazi,5Vahideh Tarhriz,6
1. Department of Biochemistry and Clinical Laboratories, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran 2. Faculty of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran 3. Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran 4. Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, Iran 5. Department of Biology, Tabriz Branch, Islamic Azad University, Tabriz, Iran 6. Molecular Medicine Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
Introduction: Timeless is an evolutionarily preserved protein involved in the circadian rhythm of melanogaster flies while its
role in mammalian circadian clock systems has not been fully elucidated. Timeless is deemed essential to protect
genomic replication and stability. Destruction of timeless in the rat suprachiasmatic nucleus disrupted the rhythm
of suprachiasmatic neural activity, reducing PER1, PER2, and PER3 and increasing cryptochrome CRY1 and
CRY2.
Methods: In addition, the full-length timeless protein showed a 24-hour fluctuation, while a truncated isoform was
substantially expressed, indicating the active role of mammals timeless in the circadian clock system. Timeless is
also involved in DNA replication, telomere length, genome integrity maintenance, and ATM/ATR signaling
pathway regulation. Recent studies have shown that timeless interacts with poly (ADP ribose) polymerase 1 and
regulates homologous recombination pathways and non-homologous end-binding pathways, both of which are
required to repair double-stranded DNA fractures.
Results: Recently, it has been reported that timeless is regulated in
different types of human tumors and is involved in the development and progression of cancer. Studies showed
that timeless, a factor involved in DNA repair, is overexpressed in cancerous tissues and is essential for the
proliferation of tumor cells. Timeless knockdown inhibits tumor growth, induces apoptosis and aging, and disrupts the DNA repair pathway in cancer cells.
Conclusion: Therefore, timeless can be a promising diagnostic marker and an
effective strategy for cancer treatment. However, more clinical research is needed to achieve many achievements
in this field.
Keywords: Circadian genes
DNA repair
Targeted cancer therapy
Gastrointestinal cancers
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