Detection of PI3K Gene Mutations in Endometrial Cancer in Iran

Document Type : Original Article (s)

Authors

1 Student, Department of Biology, School of Sciences, The Uneversity of Isfahan, Isfahan, Iran

2 Associate Professor, Department of Biology, School of Sciences, The Uneversity of Isfahan, Isfahan, Iran

3 Associate Professor, Department of Pathology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

4 Assistant Professor, Department of Radiotherapy, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Background: The phosphatidylinositol-3-kinase (PI3K) signaling pathway regulates a variety of biological processes including proliferation, motility, insulin metabolism, and apoptosis. Activated PI3K phosphorylates phosphatidylinositol 4, 5 bisphosphate [PtdIns(4,5)P2] and thus produces phosphatidylinositol 3, 4, 5 triphosphate [PtdIns(3,4,5)P3]. This lipid activates Akt (protein kinase B). The frequency of PIK3 catalytic alpha (PIK3CA) gene mutations in endometrial cancer ranges from 24% to 39%. More than 90% of the mutations in PIK3CA have been localized in the helical (exon 9) and kinase (exon 20) domains.Methods: In this study, we analyzed the presence of PIK3CA mutations by means of single-strand conformational polymorphism (SSCP) and direct DNA sequencing in a population of Iranian endometrial cancer patients in the city of Isfahan and Tehran Cancer Institute. We also investigated the correlation between PIK3CA mutations and lymph node involvement, age, and disease stage and grade by Pearson's chi-square test.Findings: Among the 47% PIK3CA mutations in this study, 60% were identified in the kinase domain (exon 20). A novel mutation was found in codon 3059 of exon 20 [C3059T (A1020V)] which has not been reported previously in endometrial cancer.  In addition to hotspot mutation of exon 9 [G1624A (E542K)], we also detected a novel mutation [G1610A (R537Q)] in exon 9. We found that PIK3CA mutations are mainly associated with histological grade of tumors (P = 0.03; OR = 5.5). However, we did not observe any significant correlations between PIK3CA mutations and lymph node involvement, stage, or age of patients. Conclusion: Our results showed that the spectrum of PIK3CA mutations in our population was different. Therefore, further research on a larger number of samples and other types of cancers would be necessary.

Keywords


  1. Jemal A, Siegel R, Xu J, Ward E. Cancer statistics, 2010. CA Cancer J Clin 2010; 60(5): 277-300.
  2. National register of cancer cases reported. [Online]. 2004. Available from: URL: http://www.ssu.ac.ir/fileadmin/templates/fa/Moavenatha/Moavenat_behdasht/MB_mobarezebimariha/Upload_MB_Mobareze/cancer/1383/National%20Cancer%20Registry_1383.pdf.
  3. Bokhman JV. Two pathogenetic types of endometrial carcinoma. Gynecol Oncol 1983; 15(1): 10-7.
  4. Hecht JL, Mutter GL. Molecular and pathologic aspects of endometrial carcinogenesis. J Clin Oncol 2006; 24(29): 4783-91.
  5. Oda K, Stokoe D, Taketani Y, McCormick F. High frequency of coexistent mutations of PIK3CA and PTEN genes in endometrial carcinoma. Cancer Res 2005; 65(23): 10669-73.
  6. Hirsch E, Braccini L, Ciraolo E, Morello F, Perino A. Twice upon a time: PI3K's secret double life exposed. Trends Biochem Sci 2009; 34(5): 244-8.
  7. Vivanco I, Sawyers CL. The phosphatidylinositol 3-Kinase AKT pathway in human cancer. Nat Rev Cancer 2002; 2(7): 489-501.
  8. Fry MJ. Structure, regulation and function of phosphoinositide 3-kinases. Biochim Biophys Acta 1994; 1226(3): 237-68.
  9. Vanhaesebroeck B, Waterfield MD. Signaling by distinct classes of phosphoinositide 3-kinases. Exp Cell Res 1999; 253(1): 239-54.
  10. Samuels Y, Wang Z, Bardelli A, Silliman N, Ptak J, Szabo S, et al. High frequency of mutations of the PIK3CA gene in human cancers. Science 2004; 304(5670): 554.
  11. Campbell IG, Russell SE, Choong DY, Montgomery KG, Ciavarella ML, Hooi CS, et al. Mutation of the PIK3CA gene in ovarian and breast cancer. Cancer Res 2004; 64(21): 7678-81.
  12. Lee S, Choi EJ, Jin C, Kim DH. Activation of PI3K/Akt pathway by PTEN reduction and PIK3CA mRNA amplification contributes to cisplatin resistance in an ovarian cancer cell line. Gynecol Oncol 2005; 97(1): 26-34.
  13. Catasus L, Gallardo A, Cuatrecasas M, Prat J. PIK3CA mutations in the kinase domain (exon 20) of uterine endometrial adenocarcinomas are associated with adverse prognostic parameters. Mod Pathol 2008; 21(2): 131-9.
  14. Hayes MP, Wang H, Espinal-Witter R, Douglas W, Solomon GJ, Baker SJ, et al. PIK3CA and PTEN mutations in uterine endometrioid carcinoma and complex atypical hyperplasia. Clin Cancer Res 2006; 12(20 Pt 1): 5932-5.
  15. Bachman KE, Argani P, Samuels Y, Silliman N, Ptak J, Szabo S, et al. The PIK3CA gene is mutated with high frequency in human breast cancers. Cancer Biol Ther 2004; 3(8): 772-5.
  16. Qiu W, Schonleben F, Li X, Ho DJ, Close LG, Manolidis S, et al. PIK3CA mutations in head and neck squamous cell carcinoma. Clin Cancer Res 2006; 12(5): 1441-6.
  17. Gharbi S, Faghihi M, Tavassoli M. A novel PIK3CA hotspot mutation in Isfahanian breast cancer patients. Cancer Invest 2011; 29(4): 313-7.