Sensitive High-Resolution Melting Analysis for Screening of KRAS and BRAF Mutations in Iranian Human Metastatic Colorectal Cancers

RAS/RAF/MAPK Pathway Mutations as Predictive Biomarkers in Middle Eastern Colorectal Cancer: A Systematic Review

Background

This review article aims to investigate the prevalence and spectrum of rat sarcoma (RAS) and V-Raf Murine Sarcoma Viral Oncogene Homolog B (BRAF) mutations, and their connection with geographical location, clinicopathological features, and other relevant factors in colorectal cancer (CRC) patients in the Middle East.

Methods

A systematic literature review, employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework, was conducted to investigate the association between the frequency of relevant mutations and the descriptive clinicopathological characteristics of CRC patients. Multiple electronic databases, including PubMed, Science Direct, Web of Science, Scopus, and Google Scholar, were searched to analyze the relevant literature.

Results

A total of 19 eligible studies comprising 2960 patients with CRC were included in this review. A comprehensive analysis of the collected literature data as well as descriptive and methodological insights is provided. Men were predominant in reviewed studies for the region, accounting for 58.6%. Overall, RAS mutation prevalence was 38.1%. Kirsten RAS Viral Oncogene Homolog (KRAS) mutations were the most common, accounting for 37.1% of cases and distributed among different exons, with the G12D mutation being the most frequent in exon 2 (23.2%) followed by G12V (13.7%), G13D (10.1%), G12C (5.1%), G12A (5.04%), and G12S (3.6%). Neuroblastoma RAS Viral Oncogene Homolog (NRAS) mutations were identified in 3.3% of tumor samples, with the most common mutation site located in exons 2, 3, and 4, and codon 61 being the most common location for the region. The total mutation frequency in the BRAF gene was 2.6%, with the V600E mutation being the most common.

Conclusion

The distribution patterns of RAS and BRAF mutations among CRC patients exhibit notable variations across diverse ethnic groups. Our study sheds light on this phenomenon by demonstrating a higher prevalence of KRAS mutations in CRC patients from the Middle East, as compared with those from other regions. The identification of these mutations and geographical differences is important for personalized treatment planning and could potentially aid in the development of novel targeted therapies. The distinct distribution patterns of RAS and BRAF mutations among CRC patients across different ethnic groups, as well as the regional variability in mutation prevalence, highlight the need for further research in this area.

Association between colorectal cancer and Fusobacterium nucleatum and Bacteroides fragilis bacteria in Iranian patients: a preliminary study

Background and aim

Recent studies have proposed that commensal bacteria might be involved in the development and progression of gastrointestinal disorders such as colorectal cancer (CRC). Therefore, in this study, the relative abundance of Fusobacterium nucleatum, Bacteroides fragilis, Streptococcus bovis/gallolyticus, and Enteropathogenic Escherichia coli (EPEC) in CRC tissues, and their association with clinicopathologic characteristics of CRC was investigated in Iranian patients. Moreover, the role of these bacteria in the CRC-associated mutations including PIK3CA, KRAS, and BRAF was studied.

Method

To these ends, the noted bacteria were quantified in paired tumors and normal tissue specimens of 30 CRC patients, by TaqMan quantitative Real-Time Polymerase Chain Reaction (qPCR). Next, possible correlations between clinicopathologic factors and mutations in PIK3CA, KRAS, and BRAF genes were analyzed.

Results

In studied samples, B. fragilis was the most abundant bacteria that was detected in 66 and 60% of paired tumor and normal samples, respectively. Furthermore, 15% of the B. fragilis-positive patients were infected with Enterotoxigenic B. fragilis (ETBF) in both adenocarcinoma and matched adjacent normal samples. F. nucleatum was also identified in 23% of tumors and 13% of adjacent normal tissue samples. Moreover, the relative abundance of these bacteria determined by 2^-ΔCT was significantly higher in CRC samples than in adjacent normal mucosa (p < 0.05). On the other hand, our findings indicated that S. gallolyticus and EPEC, compared to adjacent normal mucosa, were not prevalent in CRC tissues. Finally, our results revealed a correlation between F. nucleatum-positive patients and the KRAS mutation (p = 0.02), while analyses did not show any association between bacteria and mutation in PIK3CA and BRAF genes.

Conclusion

The present study is the first report on the analysis of different bacteria in CRC tissue samples of Iranian patients. Our findings revealed that F. nucleatum and B. fragilis might be linked to CRC. However, any link between gut microbiome dysbiosis and CRC remains unknown.

High Resolution Melting Analysis for Evaluation of mir-612 (Rs12803915) Genetic Variant with Susceptibility to Pediatric Acute Lymphoblastic Leukemia

Background

Acute lymphoblastic leukemia (ALL) is a highly heterogeneous malignancy that accounts for nearly 75% of leukemias in children. While the exact mechanism of ALL is not fully understood, some genetic variants have been implicated as associated with ALL susceptibility. The association between some genetic variants in miRNA genes and ALL risk has been described previously. A previous study suggested that mir-612 rs12803915 G> A may be associated with pediatric ALL risk. High-resolution melting (HRM) analysis is a reliable method that can be applied for polymorphism detection.

Methods

This retrospective study was performed on 100 B-ALL patients (52 males and 48 females; age 4.6 ± 3.2 years) and 105 age- and sex-matched healthy controls (48 males and 57 females; age 5.1 ± 3 years). We used HRM to identify mir-612 rs12803915 genotypes. Sanger sequencing was applied to validate the HRM results.

Results

High resolution melting analysis was used to genotype the mir-612 rs12803915 polymorphism. We found no association between rs12803915 allele A and B-ALL risk in any inheritance models (p> 0.05).

Conclusion

HRM is a suitable method to detect SNP rs12803915 in the mir-612 gene; however, we found no significant association between the rs12803915 polymorphism and ALL risk.

The Molecular Detection of Human Bocavirus (HBoV) in Colorectal Tissue with Malignant and Non-Malignant Lesions

Background: Colorectal cancer (CRC) as a worldwide human health concern is identified being a multifactorial subject that infection with specific viral particles such as oncogenic viruses is research interest. Human bocavirus (HBoV) as a recent isolated virus has been investigated in many respiratory and enteric diseases but rare studies evaluates it in tissue specimens especially in cancerous sections. The aim of this study was to detect the presence of HBoV genome and its genotyping in CRC patient’s tissue and compare the result with matched healthy control group tissue. Method: in this retrospective case-control study, CRC cases were sporadic and non-familial cancerous while control subjects had healthy or non-malignant lesions in colon tissue. A conventional-PCR performed by specific primers for HBoV VP1 gene. After sequencing of positive PCR products, raw data used for trimming and alignment by bioinformatics software CLC Main Workbench 5 and MEGA5. SPSS v.22 used for statistical calculations. Result: a total of 157 subjects were participated that 66 were diagnosed as CRC cases and 91 were non-CRC colon tissue as control group that matched by the cases. The mean age (y) ± standard deviation of each case and control groups were 59.35±14.48 and 57.21±14.66, respectively. PCR results showed there were 1.3% (2/157) HBoV positive (of each groups one was positive). Sequencing analysis showed all were HBoV-1 genotype. Conclusion: our study showed there are low rate of HBoV genome in Iranian CRC and non-CRC colon tissue. Furthermore, the predominant genotype in our studied subsets were HBoV-1 according to phylogenetic analysis.

High-resolution melting analysis coupled with next-generation sequencing as a simple tool for the identification of a novel somatic BRCA2 variant: a case report

In a 72-year-old woman with no associated personal or family history of breast and/or ovarian cancers, we identified a novel somatic pathogenic BRCA2 variant (c.18_28delAGAGAGGCCAA, p.Lys6Asnfs*4) using next-generation sequencing (NGS). The variant allele frequency (VAF) was 16%, and Sanger sequencing was unable to identify this variant. Adopting a high-resolution melting analysis strategy coupled with NGS, we successfully highlighted the presence of the c.18_28delAGAGAGGCCAA allele.

Human Papillomavirus Type 16 Integration Analysis by Real-time PCR Assay in Associated Cancers

Human papillomavirus (HPV) is a common viral infection worldwide associated with a variety of cancers. The integration of the HPV genome in these patients causes chromosomal instability and triggers carcinogenesis. The aim of this study was to investigate the HPV-16 genome physical status in four major cancers related to HPV infection. Formalin-fixed paraffin-embedded blocks from our previous projects on head and neck, colorectal, penile, and cervical cancers were collected, and HPV-16–positive specimens were used for further analysis. The DNA extraction copy number of E2 and E7 genes was calculated by qualitative real-time PCR method. Serially diluted standards that were cloned in PUC57 plasmid were used. Standard curve and melting curve analysis was used for quantification. Of the 672 specimens studied, 76 (11.3%) were HPV-16 positive. We found that 35.6% (16/45) were integrated. Statistical analysis showed that there were significant correlations between integration of HPV-16 and cervical cancer end-stage carcinogenesis (P < .0001), episomal form, and ASCUS lesions (P = .045). Significant correlation in penile cancer patients was seen between the episomal form and high-grade cancer stage (P = .037). Integration is a major factor in the carcinogenesis mechanism of HPV and has different prevalence in various cancers with a higher rate in progression except in penile cancer.

Epidermal Growth Factor Receptor Mutations in Lung Adenocarcinomas: A Single Center Study from Iran

Introduction: Lung cancer is the fifth leading tumor in Iran, and while its incidence remains relatively low, it has been increasing steadily. Targeted therapies have brought new hope to patients with non small cell lung cancer (NSCLC). The epidermal growth factor receptor (EGFR) gene is the prototype member of the type I receptor tyrosine kinase (TK) family and plays a pivotal role in cell proliferation and differentiation. Studies from Asian countries have revealed a higher frequency of EGFR mutations than in the West. The aim of this study was to measure the frequency and type of EGFR mutations in a group of Iranian patients with lung adenocarcinomas. Methods: Formalin fixed paraffin embedded (FFPE) lung adenocarcinoma tissues from 103 Iranian patients were sequentially tested for EGFR mutations by the polymerase chain reaction (PCR) followed by direct nucleotide sequencing of exons 18, 19, 20, and 21. Patient’s demographics and other clinical details were obtained from the medical records of hospitals affiliated to Iran University of Medical Sciences, Tehran, Iran. Statistical analyses were performed with SPSS v.20. Results: EGFR mutations were detected in 25/103 (24.3%) patients. The most frequent was an exon 21 point mutation (L858R) (15 patients; 60%), followed by one in exon 19 (10 patients; 40%). The frequency of EGFR mutations in never-smoker patients was significantly higher than in smokers (68% versus 32%; p < 0. 01). Conclusion: EGFR mutation frequency is higher than in the West but lower than in East Asian and almost equal to reported rates for Indian and North African populations. Smoking is negatively associated with EGFR mutations in Iranian lung adenocarcinomas.

Human Papillomavirus Investigation in Head and Neck Squamous Cell Carcinoma: Initial Report from the Low Risk HPV Types Associations

Background:

Head and neck squamous cell carcinomas (HNSCC) are a major health issue in many parts of the world. Recently, attention has focused on the human papilloma virus (HPV) as a potential causative agent for HNSCC. This study aimed to survey HPV occurrence in HNSCCs as part of a comprehensive molecular epidemiology approach.

Methods:

In this retrospective study, patients were recruited from hospitals affiliated to the Iran University of Medical Sciences, Tehran, Iran. Formalin-fixed paraffin-embedded (FFPE) blocks were subjected to DNA isolation by QIAamp® DNA FFPE Tissue Kit and nested PCR, HPV-16 specific conventional PCR, and extra INNO-LiPA HPV genotyping assays were subsequently performed. PCR products were purified with a High Pure PCR Product Purification Kit and sequenced with an ABI 3730 XL sequencer. CLC Main Workbench 5 and MEGA5 bioinformatics software was used to analyze the raw data and to create the phylogenetic tree. SPSS v.20 was applied for statistical analysis.

Results:

A total of 156 FFPE blocks were collected from 2011 to 2017. Total mean age (y) of participants was 60.5 ± 12.6; 77.6 % (121/156) being men and 22.4% (35/156) e women. Overall, 5/156 (3.2%) patients (3 females and 2 males) were found to be HPV positive using the three methods. HPV genotyping revealed HPV types 16, 2, 27, and 43 in these malignancies. Tumor location and lymph node involvement indicated significant differences between the sexes.

Conclusion:

Although high risk HPV genotypes have been associated with HNSCCs, our findings indicate a potential of low risk HPV types to also contribute to such malignancies.