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World J Gastroenterol. Mar 21, 2009; 15(11): 1381-1387
Published online Mar 21, 2009. doi: 10.3748/wjg.15.1381
Correlation of p53 over-expression and alteration in p53 gene detected by polymerase chain reaction-single strand conformation polymorphism in adenocarcinoma of gastric cancer patients from India
Sajjad Karim, Arif Ali
Sajjad Karim, Arif Ali, Department of Bio-technology, Jamia Millia Islamia, New Delhi 110025, India
Sajjad Karim, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, PO Box 80216, Jaddah-21589, Kingdom of Saudi Arabia
Author contributions: Karim S designed research, performed all experimental work and wrote the paper; Ali A was involved in designing as well as supervising the research work.
Correspondence to: Arif Ali, Professor and Head, Department of Bio-technology, Jamia Millia Islamia, New Delhi 110025, India. aliarif@rediffmail.com
Telephone: +91-11-26988335
Fax: +91-11-26988335
Received: March 18, 2008
Revised: July 7, 2008
Accepted: July 14, 2008
Published online: March 21, 2009
Abstract

AIM: To study the alterations in p53 gene among Indian gastric cancer patients and to correlate them with the various clinicopathological parameters.

METHODS: A total of 103 gastric cancer patients were included in this study. The p53 alterations were studied by both immunohistochemical method as well as polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis. We only studied four (exon 5, 6, 7, and 8) of the 11 p53 exons. The alterations in p53 were also correlated with respect to various clinicopathological parameters.

RESULTS: Among 103 cases, p53 over-expression and alteration were detected in 37 (35.92%) and 19 (18.44%) cases, respectively. Most of the p53 alterations were found at exon 5 (31.54%), followed by exon 6 (26.31%), exon 7 (21.04%) and exon 8 (21.04%). A significant correlation of p53 over-expression was found with p53 alteration (P = 0.000). Concordance between p53 alteration (as detected by SSCP) and over-expression [as detected by immunohistochemistry (IHC)] was found in 75% cases. We found that IHC-positive/SSCP-negative cases accounted for 21% of cases and IHC-negative/SSCP-positive cases accounted for remaining 4% cases.

CONCLUSION: Our results show that p53 gene mutations are significantly correlated with p53 protein over-expression, with 75% concordance in over-expression and alteration in the p53 gene, but 25% disconcordance also cautions against the assumption that p53 over-expression is always associated with a gene mutation. There may be other mechanisms responsible for stabilization and accumulation of p53 protein with no evidence of gene mutation that reflect an accumulation of a non-mutated protein, or a false negative SSCP result.

Keywords: Gastric cancer, p53, Single strand conformation polymorphism, Gene mutation, Immunohistochemistry