• Journal of Gastric Cancer
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• v.16 no.2
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• pp.85-92
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• 2016

Purpose: PIK3CA is often mutated in a variety of malignancies, including colon, gastric, ovary, breast, and brain tumors. We investigated PIK3CA expression in gastric cancer and explored the relationships between the PIK3CA expression level and clinicopathological features as well as survival of the patients. Materials and Methods: We examined PIK3CA expression in a tissue microarray of 178 gastric adenocarcinomas by immunohistochemistry and reviewed patients' medical records. Results: In our study, 112 of the 178 gastric cancer patients displayed positive PIK3CA expression. Overexpression of PIK3CA was correlated with low grade differentiation (P=0.001), frequent lymphatic invasion (P=0.032), and high T stage (P=0.040). Patients with positive PIK3CA staining were more likely to display worse overall survival rate than those with negative PIK3CA staining, as determined by Kaplan-Meier survival analysis with log-rank test (P=0.047) and a univariate analysis using the Cox proportional hazard model (hazard ratio=1.832, P=0.051). Conclusions: Elevated PIK3CA expression was significantly correlated with tumor invasiveness, tumor phenotypes, and poor patient survival.

• Genomics & Informatics
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• v.8 no.4
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• pp.194-200
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• 2010

The PIK3CA gene, oncogenic gene located on human chromosome 3q26.3, is an important regulator of cell proliferation, death, motility and invasion. To evaluate the role of PIK3CA gene in the risk of Korean lung cancer, genotypes of the PIK3CA polymorphisms (rs11709323, rs2699895, rs3729679, rs17849074 and rs1356413) were determined in 423 lung cancer patients and 443 normal controls. Statistical analyses revealed that the genotypes and haplotypes in the PIK3CA gene were not significantly associated with the risk of lung cancer in the Korean population, suggesting that these PIK3CA polymorphisms do not contribute to the genetic susceptibility to lung cancer in the Korean population.

• Journal of Breast Cancer
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• v.21 no.4
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• pp.382-390
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• 2018

Purpose: PIK3CA mutation is considered to be a possible cause for resistance to neoadjuvant chemotherapy (NAC) in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. We investigated the association between PIK3CA mutations and the outcome of NAC in HER2-positive breast cancers. Methods: A total of 100 HER2-positive breast cancer patients who had undergone NAC and surgery between 2004 and 2016 were examined. Mutation status was sequentially assessed in pre-NAC, post-NAC, and recurrent specimens taken from these patients. Results: PIK3CA mutations were identified in the sequential specimens of 17 patients (17.0%). These 17 patients experienced shorter disease-free survival (DFS) than the rest of the patients (58.3 months vs. 119.3 months, p=0.020); however, there was no significant difference in pathologic complete response (pCR) and overall survival (OS) (pCR, 17.6% vs. 33.7%, p=0.191; OS, 84.5 months vs. 118.0 months, p=0.984). While there was no difference in pCR between the wild-type and mutant PIK3CA groups in pre-NAC specimens (25.0% vs. 31.8%, p=0.199), PIK3CA mutations correlated with lower pCR in postNAC specimens (0.0% vs. 24.3%, p<0.001). Multivariate analysis revealed significantly worse DFS in the mutant PIK3CA group than in the wild-type group (hazard ratio, 3.540; 95% confidence interval, 1.001-12.589; p=0.050). Moreover, the DFS curves of the change of PIK3CA mutation status in sequential specimens were significantly different (p=0.016). Conclusion: PIK3CA mutation in HER2-positive breast cancer was correlated with a lower pCR rate and shorter DFS. These results suggest that PIK3CA mutation is a prognostic marker for NAC in HER2-positive breast cancer, especially in post-NAC specimens.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9327-9333
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• 2014

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.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.11
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• pp.4759-4768
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• 2015

Background: Several studies have investigated predictive and prognostic biomarkers for patients treated with anti-epidermal growth factor receptor (EGFR) agents in lung cancer. However, the conclusion is controversial. Materials and Methods: A meta-analysis was conducted to evaluate the associations of mutant K-ras, PIK3CA and PTEN deficiency with the efficacy of anti-EGFR agents in lung cancer. The primary endpoint was objective response rate (ORR). The secondary endpoints were overall survival (OS) and progression-free survival (PFS). Results: A total of 61 studies were included in the final meta-analysis. The result showed that K-ras mutation was a good predictor for ORR (RR=0.42, 95%CI, 0.33-0.55, p=0.000) and an effective prognostic marker for OS (HR=1.37, 95%CI, 1.15-1.65, p=0.001) and PFS (HR=1.33, 95%CI, 1.05-1.69, p=0.019). However, PTEN deficiency or PIK3CA mutation did not show any significance predictive value for ORR (PTEN, RR=0.82, 95%CI, 0.56-1.19, p=0.286; PIK3CA, RR=1.08, 95%CI, 0.17-6.66, P=0.938). And PTEN deficiency or expression of PIK3CA did not show significance prognostic value for OS (PTEN, HR=0.88, 95%CI, 0.31-2.46,P=0.805; PIK3CA, HR=0.79, 95%CI: 0.23-2.68, P=0.706). Conclusions: Our meta-analysis showed that K-ras mutation may be an effective predictor in lung cancer patients treated with anti-EGFR agents. Whereas, the predictive and prognostic value of PTEN deficiency and PIK3CA mutation need to be further investigated.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1771-1774
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• 2014

The rhabdomyosarcoma (RMS) is the most common type of soft tissue tumor in children and adolescents; yet only a few screens for oncogenic mutations have been conducted for RMS. To identify novel mutations and potential therapeutic targets, we conducted a high-throughput Sequenom mass spectrometry-based analysis of 238 known mutations in 19 oncogenes in 17 primary formalin-fixed paraffin-embedded RMS tissue samples and two RMS cell lines. Mutations were detected in 31.6% (6 of 19) of the RMS specimens. Specifically, mutations in the NRAS gene were found in 27.3% (3 of 11) of embryonal RMS cases, while mutations in NRAS, HRAS, and PIK3CA genes were identified in 37.5% (3 of 8) of alveolar RMS (ARMS) cases; moreover, PIK3CA mutations were found in 25% (2 of 8) of ARMS specimens. The results demonstrate that tumor profiling in archival tissue samples is a useful tool for identifying diagnostic markers and potential therapeutic targets and suggests that these HRAS/ PIK3CA mutations play a critical role in the genesis of RMS.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.9
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• pp.5117-5122
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• 2013

Purpose: To explore the association between PIK3CA and AKT single nucleotide polymorphisms(SNP) and osteosarcoma susceptibility. Methods: TaqMan polymerase chain reaction(PCR) was used to detect the genotypes of SNPs (rs7646409, rs6973569 and rs9866361) in peripheral blood samples from 59 patients with osteosarcoma and from 63 healthy controls. Unconditional logistic regression was used to analyze the correlation between SNPs and osteosarcoma risk. Results: No statistically significant difference was found between osteosarcoma patients and healthy controls in the genotype of AKT rs6973569 (P=0.7). However, after stratified analysis, the genotype AA of AKT rs6973569 carried a higher risk of osteosarcoma metastasis (OR:2.94, 95%CL:1.00-8.59); the difference of rs7646409 genotype distributions between the case and control groups was statistically significant (P=0.032). Taking genotype TT as a reference, the risk of osteosarcoma increased three fold in patients with genotype CC (OR:3.47, 95%CL:1.26-9.56). A statistically significant difference was found between the alleles C and T (P=0.005). Further analysis showed that the risk factor was more pronounced in male patients with Enneking's stage IIB and osteoblastic osteosarcoma. PIK3CA rs9866361 did not fit Hardy-Weinberg equilibrium (P<0.05). Conclusions: Genotype CC in locus PIK3CA rs7646409 may increase the risk of osteosarcoma in the Chinese population.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5599-5603
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• 2012

Background: The epidermal growth factor receptor (EGFR) is a potential therapeutic target for breast cancer treatment; however, its use does not lead to a marked clinical response. Studies of non-small cell lung cancer and colorectal cancer showed that mutations of genes in the PIK3CA/AKT and RAS/RAF/MEK pathways, two major signalling cascades downstream of EGFR, might predict resistance to EGFR-targeted agents. Therefore, we examined the frequencies of mutations in these key EGFR pathway genes in Chinese breast cancer patients. Methods: We used a high-throughput mass-spectrometric based cancer gene mutation profiling platform to detect 22 mutations of the PIK3CA, AKT1, BRAF, EGFR, HRAS, and KRAS genes in 120 Chinese women with breast cancer. Results: Thirteen mutations were detected in 12 (10%) of the samples, all of which were invasive ductal carcinomas (two stage I, six stage II, three stage III, and one stage IV). These included one mutation (0.83%) in the EGFR gene (rs121913445-rs121913432), three (2.50%) in the KRAS gene (rs121913530, rs112445441), and nine (7.50%) in the PIK3CA gene (rs121913273, rs104886003, and rs121913279). No mutations were found in the AKT1, BRAF, and HRAS genes. Six (27.27%) of the 22 genotyping assays called mutations in at least one sample and three (50%) of the six assays queried were found to be mutated more than once. Conclusions: Mutations in the EGFR pathway occurred in a small fraction of Chinese breast cancers. However, therapeutics targeting these potential predictive markers should be investigated in depth, especially in Oriental populations.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2743-2746
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• 2013

Background: Dilantin sodium (phenytoin) is an antiepileptic drug, which is routinely used to control generalized tonic clonic seizure and partial seizure episodes. A few case reports of oral squamous cell carcinomas arising from regions of phenytoin induced gingival overgrowth (GO), and overexpression of mitogenic factors and p53 have presented this condition as a pathology with potential to transform into malignancy. We recently investigated the genetic status of p53 and H-ras, which are known to be frequently mutated in Indian oral carcinomas in GO tissues and found them to only contain wild type sequences, which suggested a non-neoplastic nature of phenytoin induced GO. However, besides p53 and H-ras, other oncogenes and tumor suppressors such as PIK3CA, p14ARF, p16INK4a and $p21^{Waf1/Cip1}$, are frequently altered in oral squamous cell carcinoma, and hence are required to be analyzed in phenytoin induced GO tissues to be affirmative of its non-neoplastic nature. Methods: 100ng of chromosomal DNA isolated from twenty gingival overgrowth tissues were amplified with primers for exons 9 and 20 of PIK3CA, exons $1{\alpha}$, $1{\beta}$ and 2 of p16INK4a and p14ARF, and exon 2 of $p21^{Waf1/Cip1}$, in independent reactions. PCR amplicons were subsequently gel purified and eluted products were sequenced. Results: Sequencing analysis of the twenty samples of phenytoin induced gingival growth showed no mutations in the analyzed exons of PIK3CA, p14ARF, p16INK4a and $p21^{Waf1/Cip1}$. Conclusion: The present data indicate that the mutational alterations of genes, PIK3CA, p14ARF, p16INK4a and $p21^{Waf1/Cip1}$ that are frequently mutated in oral squamous cell carcinomas are rare in phenytoin induced gingival growth. Thus the findings provide further evidence that phenytoin induced gingival overgrowth as a non-neoplastic lesion, which may be considered as clinically significant given the fact that the epileptic patients are routinely administered with phenytoin for the rest of their lives to control seizure episodes.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.5
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• pp.2731-2731
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• 2016