Novel mutations of PIK3CA gene in head and neck squamous cell carcinoma

Understanding PI3K/Akt/mTOR signaling in squamous cell carcinoma: mutated PIK3CA as an example

Compared with those in adenocarcinoma, PIK3CA mutations are more common in squamous cell carcinoma (SCC), which arises from stratified squamous epithelia that are usually exposed to adverse environmental factors. Although hotspot mutations in exons 9 and 20 of PIK3CA, including E542K, E545K, H1047L and H1047R, are frequently encountered in the clinic, their clinicopathological meaning remains to be determined in the context of SCC. Considering that few reviews on PIK3CA mutations in SCC are available in the literature, we undertook this review to shed light on the clinical significance of PIK3CA mutations, mainly regarding the implications and ramifications of PIK3CA mutations in malignant cell behavior, prognosis, relapse or recurrence and chemo- or radioresistance of SCC. It should be noted that only those studies regarding SCC in which PIK3CA was mutated were cherry-picked, which fell within the scope of this review. However, the role of mutated PIK3CA in adenocarcinoma has not been discussed. In addition, mutations occurring in other main members of the PI3K-AKT-mTOR signaling pathway other than PIK3CA were also excluded.

Novel Method for Detection of PIK3CA Mutations in Circulating Tumor DNA of Patients with Colorectal Cancer

The PIK3CA mutation is considered a potential target for treatment of colorectal cancer. We evaluated a PIK3CA mutation assay on plasma cell-free DNA (cfDNA) using a newly developed PCR with restriction digestion integrated and followed by Sanger's sequencing. We analyzed PIK3CA mutation in plasma with our newly developed assays and in matching tumor tissues by routine methods. We detected the PIK3CA gene mutation status by both methods in samples from 40 colorectal cancer patients. Three H1047R mutations of PIK3CA gene were detected in the cfDNA of the 40 patients by restriction digestion PCR. Neither E545K nor H1047R mutations were detected in the cfDNA by routine PCR/sequencing. The PIK3CA H1047R and E545K mutations in cfDNA can be sensitively detected with our newly developed assays. The colorectal cancer has been used as a clinical example in testing our new assays, which indicates that the new assays may have wider applications in detecting mutations in precision oncology. Trial registration: Current Controlled Trials ChiCTR-DDT-12002848, 8 October 2012.

Worldwide prevalence of PI3K-AKT-mTOR pathway mutations in head and neck cancer: A systematic review and meta-analysis

A systematic review (SR) and meta-analysis were conducted to determine the prevalence of PI3K-AKT-mTOR signaling pathway mutations in patients with head and neck cancer (HNC). Overall, 105 studies comprising 8630 patients and 1306 mutations were selected. The estimated mutations prevalence was 13 % for PIK3CA (95 % confidence interval [CI] = 11-14; I² = 82 %; p < 0.0001), 4% for PTEN (95 % CI = 3-5; I² = 55 %; p < 0.0001), 3% for MTOR (95 % CI = 2-4; I² = 5%; p = 0.40), and 2% for AKT (95 % CI = 1-2; I² = 50 %; p = 0.0001). We further stratified the available data of the participants according to risk factors and tumor characteristics, including HPV infection, tobacco use, alcohol exposure, TNM stage, and histological tumor differentiation, and performed subgroup analysis. We identified significant associations between PI3K-AKT-mTOR pathway-associated mutations and advanced TNM stage (odds ratio [OR] = 0.20; 95 % CI = 0.09-0.44; I² = 71 %; p = 0.0001) and oropharyngeal HPV-positive tumors and PIK3CA mutations (OR = 17.48; 95 % CI = 4.20-72.76; I² = 69 %; p < 0.0002). No associations were found between alcohol and tobacco exposure, and tumor differentiation grade. This SR demonstrated that the PI3K-AKT-mTOR pathway emerges as a potential prognostic factor and could offer a molecular basis for future studies on therapeutic targeting in HNC patients.

Current concepts in ameloblastoma-targeted therapies in B-raf proto-oncogene serine/threonine kinase V600E mutation: Systematic review

BACKGROUND

Ameloblastomas are common benign epithelial odontogenic neoplasms that present an aggressive and unpredictable behavior that may modify treatment strategies. Different signaling pathways that participate in the progression of these tumors have been identified. B-raf proto-oncogene serine/threonine kinase (BRAF) is a protein involved in the behavior of ameloblastomas, and it is related to many cell mechanisms. BRAF gene mutations have been identified in ameloblastomas, of which the BRAF V600E (valine substituted by glutamic acid at amino acid 600) mutation has been the most common and can be present concomitantly with other mutations that may be involved in its behavior. Targeted therapies have been used as an alternative in the case of resistance or contraindications to conventional treatments.

AIM

To document the presence of BRAF V600E and additional mutations, their behavior, and targeted therapies in these tumors.

METHODS

An electronic literature search was conducted according to PRISMA guidelines in PubMed/MEDLINE, Cochrane, EMBASE, and SpringerLink using the terms “ameloblastomas”, “BRAF V600E”, “additional mutations”, and “targeted therapies”. Ameloblastomas were classified according to WHO guidelines. Inclusion criteria were articles in English, published not more than 10 years ago, and studies with laboratory works related to BRAF V600E. Articles were evaluated by two independent reviewers and retrieved for full-text evaluation. The EBLIP Critical Appraisal Checklist was used to evaluate the quality of the eligible studies. Descriptive statistical analysis was performed.

RESULTS

Two independent reviewers, with a substantial concordance indicated by a kappa coefficient of k = 0.76, evaluated a total of 19 articles that were included in this study. The analysis registered 521 conventional ameloblastomas (AM), 81 unicystic ameloblastomas (UA), 13 ameloblastic carcinomas (AC), three metastatic ameloblastomas (MA), and six peripheral ameloblastomas (PA), of which the histopathological type, anatomic location, laboratory tests, expression of BRAF mutation, and additional mutations were registered. The BRAF V600E mutation was found in 297 AM (57%), 63 UA (77.7%), 3 AC (23%), 1 MA (50%), and 5 PA (83.3%). Follicular type predominated with a total of 116 cases (40%), followed by plexiform type with 63 cases (22.1%). Furthermore, both types presented additional mutations, in which alterations in JAK3 P132T, SMARCB1, PIK3CA, CTNNB1, SMO, and BRAF G606E genes were found. Four case reports were found with targeted therapy to BRAF V600E.

CONCLUSION

The identification of BRAF V600E and additional mutations as an aid in targeted therapies has been a breakthrough in alternative treatments of ameloblastomas where surgical treatments are contraindicated.

Helical and kinase domain mutations of PIK3CA, and their association with hormone receptor expression in breast cancer

Breast cancer is one of the major causes of female morbidity and mortality, accounting for ~25% of the total cancer cases in women. Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic α subunit (PIK3CA) mutations serve a major role in downstream signaling of receptor tyrosine kinases. The present study aimed to elucidate the frequency of exon 9 and 20 mutations of PIK3CA and their role in disease progression. A total of 118 tumor samples from confirmed breast cancer patients were collected from the histopathology laboratory at King Fahd Hospital of the University (Al-Khobar, Saudi Arabia). Sanger sequencing was performed on extracted DNA to identify the mutations on exons 9 and 20 of PIK3CA. The results were further validated by competitive allele-specific TaqMan polymerase chain reaction. Three mutations, namely E542K and E545K within exon 9, and H1047R within exon 20, were observed in 25 patients (21.2%). Among these, 18 patients carried the H1047R mutation of the kinase domain, while the remaining 7 patients carried mutations in the helical domain. PIK3CA mutations were associated with the estrogen receptor-positive/progesterone receptor-positive (ER⁺/PR⁺) group of tumors in contrast to the ER⁻/PR⁻ group (P=0.021). Furthermore, it was observed that the PIK3CA mutation was associated with a poor disease prognosis. Taken together, the current study emphasized the potential of PIK3CA mutations as an important biomarker for breast cancer classification and the possible use of PIK3CA inhibitor as targeted therapy for breast cancer.

Association of Uncoupling Protein 1 (UCP1) gene polymorphism with obesity: a case-control study

BACKGROUND

Obesity is one of the main causes of morbidity and mortality worldwide. More than 120 genes have been shown to be associated with obesity related phenotypes. The aim of this study was to determine the effect of selected genetic polymorphisms in Uncoupling protein 1 (UCP1) and Niemann-Pick C1 (NPC1) genes in an obese population in Saudi Arabia.

METHODS

The genotypes of rs1800592, rs10011540 and rs3811791 (UCP1 gene) and rs1805081 and rs1805082 (NPC1 gene) were determined in a total of 492 subjects using TaqMan chemistry by Real-time PCR. In addition, capillary sequencing assay was performed to identify two specific polymorphisms viz., rs45539933 (exon 2) and rs2270565 (exon 5) of UCP1 gene.

RESULTS

A significant association of UCP1 polymorphisms rs1800592 [OR, 1.52 (1.10-2.08); p = 0.009] was observed in the obese cohort after adjusting with age, sex and type 2 diabetes. Further BMI based stratification revealed that this association was inconsistent with both moderate and extreme obese cohort. A significant association of UCP1 polymorphisms rs3811791 was observed only in the moderate-obese cohort [OR = 2.89 (1.33-6.25); p = 0.007] but not in the extreme-obese cohort indicating an overlying genetic complexity between moderate-obesity and extreme-obesity. The risk allele frequencies, which were higher in moderate-obese cohort, had abnormal HDL, LDL and triglyceride levels.

CONCLUSION

The rs1800592 and rs3811791 of UCP1 gene are associated with obesity in general and in the moderate-obese group in particular. The associated UCP1 polymorphisms in the moderate-obese group may regulate the impaired energy metabolism which plays a significant role in the initial stages of obesity.

Tyrosine kinase domain mutations of EGFR gene in head and neck squamous cell carcinoma

Background

Epidermal growth factor receptor (EGFR) is a commonly altered gene that is identified in various cancers, including head and neck squamous cell carcinoma (HNSCC). Therefore, EGFR is a promising molecular marker targeted by monoclonal antibodies and small molecule inhibitors targeting the tyrosine kinase (TK) domain.

Objective

The objective of this study was to investigate the spectrum of mutations in exons 18, 19, 20, and 21 of the EGFR gene in HNSCC patients.

Materials and methods

This retrospective study included 47 confirmed HNSCC cases. Mutations in the TK domain, exons 18, 19, 20, and 21 of the EGFR gene, were detected by Scorpion^® chemistry and ARMS^® technologies on Rotor-Gene Q real-time polymerase chain reaction.

Results

The tumors exhibited EGFR-TK domain mutations in 57% of cases. Four cases of T790M mutations were reported for the first time among HNSCC patients. Out of the total mutations, L861Q (exon 21), exon 20 insertions and deletions of exon 19 accounted for the majority of mutations (21%, 19%, and 17%, respectively). EGFR mutation status was correlated with the higher grade (P=0.026) and advanced stage (P=0.034) of HNSCC tumors.

Conclusion

Higher frequency of EGFR-TK domain mutations together with the presence of the T790M mutation suggests that identification of these mutations might streamline the therapy and provide a better prognosis in HNSCC cases.

Applications of molecular testing in surgical pathology of the head and neck

Molecular testing in routine surgical pathology is becoming an important component of the workup of many different types of tumors. In fact, in some organ systems, guidelines now suggest that the standard of care is to obtain specific molecular panels for tumor classification and/or therapeutic planning. In the head and neck, clinically applicable molecular tests are not as abundant as in other organ systems. Most current head and neck biomarkers are utilized for diagnosis rather than as companion diagnostic tests to predict therapeutic response. As the number of potential molecular biomarker assays increases and cost pressures escalate, the pathologist must be able to navigate the molecular testing pathways. This review explores scenarios in which molecular testing might be beneficial and cost-effective in head and neck pathology.