Hypoxia-induced immortalization of primary cells depends on Tfcp2L1 expression

Area of Science:

• Cellular and Molecular Biology
• Cancer Research
• Stem Cell Biology

Background:

• Cellular senescence is a protective mechanism against uncontrolled proliferation.
• Hypoxia is known to extend cellular lifespan and reduce oxidative damage, but the underlying mechanisms prior to malignancy are unclear.

Purpose of the Study:

• To investigate how hypoxia promotes extended cellular lifespan and bypasses senescence in mouse embryonic fibroblasts (MEFs) before malignant transformation.
• To identify key molecular regulators involved in hypoxia-induced cellular immortalization.

Main Methods:

• Culture of MEFs under hypoxic and normoxic conditions.
• Analysis of senescence markers (p16INK4a, p15INK4b, p21Cip1) and stemness genes (Tfcp2l1, Oct3/4, Sox2, Nanog).
• Chromatin accessibility (ATAC-seq) and ChIP-sequencing (ChIP-seq) to identify Tfcp2l1 regulatory targets.

Main Results:

• Hypoxia significantly increased MEF lifespan by downregulating senescence markers.
• Proliferating MEFs in hypoxia overexpressed Tfcp2l1, a pluripotency regulator, along with stemness genes Oct3/4, Sox2, and Nanog.
• Tfcp2l1, regulated by Hif1α under hypoxia, was shown to control genes involved in proliferation and stemness (Sox2, Sox9, Jarid2, Ezh2) and promote cellular reprogramming.

Conclusions:

• Hypoxia-induced activation of Tfcp2l1 contributes to cellular immortalization prior to malignant transformation.
• Tfcp2l1 plays a critical role in facilitating tumorigenesis and dedifferentiation by regulating key stemness and proliferation genes.