Related Experiment Video

Updated: Jun 15, 2026

An In Vitro Protocol for Evaluating MicroRNA Levels, Functions, and Associated Target Genes in Tumor Cells
09:45

An In Vitro Protocol for Evaluating MicroRNA Levels, Functions, and Associated Target Genes in Tumor Cells

Published on: May 21, 2019

MicroRNA and proliferation control in chronic lymphocytic leukemia: functional relationship between miR-221/222

Michela Frenquelli1, Marta Muzio, Cristina Scielzo

  • 1Department of Oncology, Unit and Laboratory of Lymphoid Malignancies, San Raffaele Scientific Institute and Universita Vita-Salute San Raffaele, Milan, Italy.

Blood
|March 6, 2010
PubMed

Insights

MicroRNA 221/222 (miR-221/222) regulates p27 protein levels in chronic lymphocytic leukemia (CLL) cells. This interaction influences cell cycle progression and may maintain CLL cells in a resting state.

Area of Science:

  • Hematology
  • Molecular Biology
  • Oncology

Background:

  • Chronic lymphocytic leukemia (CLL) is a B-cell malignancy characterized by the accumulation of leukemic cells.
  • The cell cycle regulator p27 plays a crucial role in controlling cell proliferation.
  • MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and are implicated in various cancers, including CLL.

Purpose of the Study:

  • To investigate the functional relationship between the microRNA 221/222 (miR-221/222) cluster and p27 in chronic lymphocytic leukemia (CLL).
  • To determine if miR-221/222 influences p27 expression and cell cycle progression in CLL cells.

Main Methods:

  • Enforced expression of miR-221/222 in the MEC1 CLL cell line.
  • Analysis of miR-221/222 and p27 protein expression in peripheral blood (PB) and other anatomical compartments (lymph nodes, bone marrow) from CLL patients.
  • Induction of cell cycle entry in CLL cells in vitro.

Main Results:

  • Enforced miR-221/222 expression in MEC1 cells led to decreased p27 protein levels and enhanced proliferation.
  • An inverse correlation between miR-221/222 and p27 expression was observed in leukemic cells from CLL patients.
  • Higher miR-221/222 expression and lower p27 levels were found in lymph nodes and bone marrow compared to PB.
  • Inducing cell cycle entry in CLL cells increased miR-221/222 expression and decreased p27 protein.

Conclusions:

  • The miR-221/222 cluster modulates p27 protein expression in CLL cells.
  • miR-221/222 and p27 may form a regulatory loop contributing to the maintenance of CLL cells in a quiescent state.
  • These findings highlight a potential therapeutic target for modulating CLL cell proliferation.

More Related Videos

Describing a Transcription Factor Dependent Regulation of the MicroRNA Transcriptome07:23

Describing a Transcription Factor Dependent Regulation of the MicroRNA Transcriptome

Published on: June 15, 2016

CRISPR Gene Editing Tool for MicroRNA Cluster Network Analysis10:40

CRISPR Gene Editing Tool for MicroRNA Cluster Network Analysis

Published on: April 25, 2022

Related Concept Videos

Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
MicroRNAs01:22

MicroRNAs

MicroRNA (miRNA) are short, regulatory RNA transcribed from introns (non-coding regions of a gene) or intergenic regions (stretches of DNA present between genes). Several processing steps are required to form biologically active, mature miRNA. The initial transcript, called primary miRNA (pri-mRNA), base-pairs with itself, forming a stem-loop structure. Within the nucleus, an endonuclease enzyme, called Drosha, shortens the stem-loop structure into hairpin-shaped pre-miRNA. After the pre-miRNA...
MicroRNAs01:22

MicroRNAs

MicroRNA (miRNA) are short, regulatory RNA transcribed from introns—non-coding regions of a gene—or intergenic regions—stretches of DNA present between genes. Several processing steps are required to form biologically active, mature miRNA. The initial transcript, called primary miRNA (pri-mRNA), base-pairs with itself forming a stem-loop structure. Within the nucleus, an endonuclease enzyme, called Drosha, shortens the stem-loop structure into hairpin-shaped pre-miRNA. After the pre-miRNA ends...
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
Interactions Between Signaling Pathways01:19

Interactions Between Signaling Pathways

Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.