Journal List > J Lung Cancer > v.9(2) > 1050722

Kim, Yoo, and Lee: Mutational and Expressional Analysis of ATG5 Gene in Non-Small Cell Lung Cancers

Abstract

Purpose

Several lines of evidence have indicated that perturbations of autophagy are involved in the development of many human diseases, including cancer. The autophagy-related genes (ATG) encode proteins that play important roles in autophagic processes. The aim of this study was to see whether alterations of the ATG5 protein expression and somatic mutations of the ATG5 gene are present in human non-small cell lung cancers (NSCLCs).

Materials and Methods

We analyzed the ATG5 somatic mutations in 45 NSCLCs by performing single-strand conformation polymorphism (SSCP). We examined the ATG5 protein expression in 45 NSCLCs by performing immunohistochemistry.

Results

The SSCP analysis revealed no evidence of somatic mutation in the DNA sequences encoding the ATG5 gene in the 45 NSCLCs. On the immunohistochemistry, ATG5 protein was expressed in the normal bronchial epithelial cells, while it was lost in 9 (20%) of the NSCLCs.

Conclusion

Our data indicates that ATG5 is altered in NSCLC at the expressional level, but not at the mutational level. The data also suggests that the loss of expression of ATG5 might play a role in the pathogenesis of NSCLC by altering autophagic and apoptotic cell death.

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Figures and Tables

Fig. 1.
Representative single-strand conformation polymorphism (SSCP) of ATG5 gene in non-small cell lung cancers. Exon 5 of ATG5 gene was amplified by PCR using a specific primer set. The PCR products from three representative cases of non-small cell lung cancers were visualized on SSCP. SSCP of DNA from the non-small cell lung cancers (T) shows no aberrant bands as compared to SSCPs from the normal tissues (N).
jlc-9-72f1.tif
Fig. 2.
Visualization of ATG5 expression in non-small cell lung cancer tissues by immunohistochemistry. (A) A squamous cell carcinoma shows ATG5 immunostaining in the cancer cells. (B) A adenocarcinoma shows ATG5 immunostaining in the cancer cells. (C) In another adenocarcinoma, the cancer cells are negative for ATG5 immunostaining. (D) Normal bronchial epithelial cells are positive for ATG5 immunostaining (original magnification A∼ C, ×200; D, ×150).
jlc-9-72f2.tif
Table 1.
Primer Sequences of ATG5 Gene Used in This Study
Gene Sequences Size, bp
ATG5 Exon 4 F: 5'-TTCTCAAAATATACTGTTTC-3' 154
  R: 5'-TATTATGTATCACAAATGG-3'  
ATG5 Exon 5–1 F: 5'-CTGGGGGATATAGTTCTCTT-3' 204
  R: 5'-TGCATTTCATTGATTACTTG-3'  
ATG5 Exon 5–2 F: 5'-CAATTGAAGCTCATTTTATG-3' 197
  R: 5'-AACTACTCACAGGGTTATGG-3 '
ATG5 Exon 6 F: 5'-TCTCTTCATGTGAGGTATTC-3' 184
  R: 5'-CTGAGGCTTTCATAAATG-3'  
ATG5 Exon 7 F: 5'-AAGACTTAATTGCTTGAATC-3' 187
  R: 5'-AATGTTTTAATGTTGCTGA-3'  
ATG5 Exon 8 F: 5'-GACTTTTATTGTTGTTGGGTTTC-3' 173
  R: 5'-TCAATCTGTTGGCTGTGG-3'  
Table 2.
Summary of ATG5 Expression in the Lung Cancers
Histologic types ATG5 expression
Squamous cell carcinoma (n=22) 6 16
Adenocarcinoma (n=23) 3 20
Total, n (%) 9 (20) 36 (80)
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