title: Detection of PIK3CA gene mutations with HRM analysis and association with IGFBP-5 expression levels in breast cancer.
abstract: Breast cancer is the second most common cancer and second leading cause of cancer deaths in women. Phosphatidylinositol-3-kinase (PI3K)/AKT pathway mutations are associated with cancer and phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene mutations have been observed in 25-45% of breast cancer samples. Insulin growth factor binding protein-5 (IGFBP-5) can show different effects on apoptosis, cell motility and survival in breast cancer. We here aimed to determine the association between PIK3CA gene mutations and IGFBP-5 expressions for the first time in breast cancer patients. Frozen tumor samples from 101 Turkish breast cancer patients were analyzed with high resolution melting (HRM) for PIK3CA mutations (exon 9 and exon 20) and 37 HRM positive tumor samples were analyzed by DNA sequencing, mutations being found in 31. PIK3CA exon 9 mutations (Q546R, E542Q, E545K, E542K and E545D) were found in 10 tumor samples, exon 20 mutations (H1047L, H1047R, T1025T and G1049R) in 21, where only 1 tumor sample had two exon 20 mutations (T1025T and H1047R). Moreover, we detected one sample with both exon 9 (E542Q) and exon 20 (H1047R) mutations. 35% of the tumor samples with high IGFBP-5 mRNA expression and 29.4% of the tumor samples with low IGFBP-5 mRNA expression had PIK3CA mutations (p=0.9924). This is the first study of PIK3CA mutation screening results in Turkish breast cancer population using HRM analysis. This approach appears to be a very effective and reliable screening method for the PIK3CA exon 9 and 20 mutation detection. Further analysis with a greater number of samples is needed to clarify association between PIK3CA gene mutations and IGFBP-5 mRNA expression, and also clinical outcome in breast cancer patients.
authors.affiliation: Department of Medical Biology, School of Medicine, Marmara University, Istanbul, Turkey E-mail : makkiprik@marmara.edu.tr.
authors.forename: Ebubekir
authors.initials: E
authors.lastname: Dirican
authors.forename: Zehra
authors.initials: Z
authors.lastname: Kaya
authors.forename: Gokce
authors.initials: G
authors.lastname: Gullu
authors.forename: Irem
authors.initials: I
authors.lastname: Peker
authors.forename: Tolga
authors.initials: T
authors.lastname: Ozmen
authors.forename: Bahadir M
authors.initials: BM
authors.lastname: Gulluoglu
authors.forename: Handan
authors.initials: H
authors.lastname: Kaya
authors.forename: Ayse
authors.initials: A
authors.lastname: Ozer
authors.forename: Mustafa
authors.initials: M
authors.lastname: Akkiprik
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D001943:Breast Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D058534:Class I Phosphatidylinositol 3-Kinases; D018450:Disease Progression; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D005629:Frozen Sections; D015972:Gene Expression Regulation, Neoplastic; D056726:Genetic Association Studies; D006801:Humans; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000235:genetics*; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009361:Neoplasm Invasiveness / Q000473:pathology; D009367:Neoplasm Staging; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D015183:Restriction Mapping / Q000379:methods; D018570:Risk Assessment; D017422:Sequence Analysis, DNA / Q000379:methods; D018709:Statistics, Nonparametric; D015996:Survival Rate; D014421:Turkey
chemical_list: D018975:Insulin-Like Growth Factor Binding Protein 5; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human