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LIN28B confers radio-resistance through the posttranscriptional control of KRAS

Sun-Hye Jeong1, Hong-Gyun Wu, Woong-Yang Park

  • 1Department of Biomedical Sciences, Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 110-799, Korea.

Experimental & Molecular Medicine
|September 12, 2009
PubMed

Insights

This study identifies let-7g as a key microRNA in radio-resistance for lung cancer. LIN28B inhibits let-7g, increasing resistance to ionizing radiation (IR) by promoting KRAS translation.

Area of Science:

  • Oncology
  • Molecular Biology
  • Radiotherapy

Background:

  • Radio-resistance is a major challenge in lung cancer treatment.
  • MicroRNAs (miRNAs) are increasingly recognized as regulators of cellular responses to radiation.
  • Identifying specific miRNAs involved in radio-resistance can reveal novel therapeutic targets.

Purpose of the Study:

  • To identify differentially expressed microRNAs associated with radio-resistance in lung cancer cells.
  • To investigate the role of let-7g and its regulatory pathway in cellular response to ionizing radiation (IR).

Main Methods:

  • Microarray analysis of miRNA profiles in lung cancer cell lines with varying IR responses.
  • Quantitative real-time PCR (qRT-PCR) to validate miRNA expression levels.
  • Functional studies involving miRNA over-expression, gene knockdown, and assessment of IR sensitivity.

Main Results:

  • 27 microRNAs were differentially expressed between radio-resistant and sensitive lung cancer cells.
  • let-7g was significantly down-regulated in radio-resistant cells and its over-expression increased IR sensitivity.
  • Knockdown of LIN28B, an upstream regulator, increased mature let-7g levels and enhanced IR sensitivity.

Conclusions:

  • LIN28B inhibits let-7g processing, contributing to radio-resistance in lung cancer cells.
  • The LIN28B/let-7g/KRAS pathway is a critical determinant of cellular response to ionizing radiation.
  • Targeting the LIN28B-let-7g axis may represent a novel strategy to overcome radio-resistance in lung cancer.

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