International ISSN: 2471-0016 ICPJL

Clinical Pathology Journal
Research Article
Volume 3 Issue 2 - 2016
Sensitive High-Resolution Melting (HRM) Analysis for Screening of KRAS and BRAF Mutations in Iranian Human Metastatic Colorectal Cancer (mCRC)
Mohammad Hadi Karbalaie Niya1, Fahimeh Safarnezhad Tameshkel2, Aghigh koochak2, Nasser Rakhshani2*, Farhad Zamani2, Farid Imanzade3, Hamid Rezvani4, Hossein Ajdarkosh2, Ali Basi2, Mohammad Mahdi Adib-sereshki2, Mohsen Razavi2 and Masoud Reza Sohrabi2
1Department of Virology, Iran University of Medical Sciences, Iran
2Gastrointestinal and liver diseases research center, Iran University of Medical Sciences, Iran
3Department of pediatrics, shahid beheshti University of Medical Sciences, Iran
4Department of Oncology, Shahid Beheshti University of Medical Sciences, Iran
Received: October 22, 2016 | Published: November 16, 2016

*Corresponding author: Nasser Rakhshani, Gastrointestinal and liver diseases research center, firoozgar hospital, Iran University of Medical Sciences. Tehran, Iran, Tel: +989121541192, E-mail:

Citation: Niya MHK, Tameshkel FS, koochak A, Rakhshani N, Zamani F, et al. (2016) Sensitive High-Resolution Melting (HRM) Analysis for Screening of KRAS and BRAF Mutations in Iranian Human Metastatic Colorectal Cancer (mCRC). Int Clin Pathol J 3(2): 00071. DOI: 10.15406/icpjl.2016.03.00071

Abstract

Background: investigations in the methods of mutation detection uncovered the major weaknesses of direct sequencing and pyrosequencing; they have high costs and low sensitivity for the screening of known or unknown mutations. High resolution melting (HRM) analysis seems to be an alternative tool for the rapid detection of mutations. Here we describe the accuracy of HRM in screening KRAS and BRAF mutations in metastatic colorectal cancer (mCRCs) samples.

Materials and methods: In this regard, we examined 1000 mCRC patients in Mehr Hospital, Tehran, Iran, from Feb. 2008 to May 2012 for KRAS mutations and 242 of them were selected for BRAF mutations by the HRM analysis. In order to calculate the sensitivity and specificity, HRM results were checked by pyrosequencing as the golden standard and Dxs Therascreen as another method.

Results: from the total of 1000 participants, there were 664 (66.4%) wild types and 336 (33.6%) mutants of KRAS gene in codon 12 and 13. Among 242 samples that randomly checked for BRAF gene, all were detected as wild type by HRM. Pyrosequencing and Dxs Therascreen results were in line with that of the HRM. In this regards, the sensitivity and specificity of HRM evaluated as 100%.

Conclusion: The findings suggest that the HRM, in comparison with DNA sequencing, is a more appropriate method for precise scanning of KRAS and BRAF mutations. It is also possible to state that HRM may be a more attractive technique for the detection of known or unknown somatic mutations of other genes.

Keywords: High-Resolution Melting (HRM); Mutation Analysis; KRAS; BRAF; metastatic colorectal cancer (mCRC); pyrosequencing; Dxs Therascreen

Abbreviations

HRM: High-Resolution Melting; mCRC: metastatic colorectal cancer; CRC: Colorectal Cancer; FFPE: Formalin-fixed paraffin-embedded;

Introduction

Rapid and reliable genetic screening method of human cancers is one of the interesting fields of research [1]. There are several diagnostic methods for the investigation of cancerous mutational status of patients such as direct DNA sequencing and pyrosequencing (golden standard), TaqMan array, single-strand conformation analysis, allele-specific PCR (Dxs Therascreen), but they have some defects, including needing manipulation of amplified fragments or being labor intensive and time consuming [2-8].

Sanger sequencing, is approved as a gold standard of sequence variation analysis and has high reliability but its disadvantages raised the applicability limitation as a diagnostic tool in routine laboratories and restricted its functionality in research centers, respectively. One of its weak points is the use of several steps by distinct protocols (e.g. PCR, amplicon purification, labeling) that increased the contamination risks [5,6,9]. Given that, Sanger sequencing pitfalls such as being time-consuming, labor-intensive, and expensive or being in need of sophisticated devices introduce the suggestion of its gradual replacement by other sensitive, reliable, and efficient methods [5,6,9].

High resolution melting (HRM) analysis is a high throughput emerging PCR-based method for rapid scanning of hereditary or somatic mutations with high accuracy [1,9,10]. The screening of mutations by this method is based on the measurement of modifications in the melting profile of duplex, when the DNA is exposed to an increasing temperature. These modifications monitored using the fluorescent dyes, which intercalate double-stranded fragments but no single-stranded fragments [11]. Patterns of melting profile influenced by various variants, as a result wild type and homozygote-heterozygote sequences have different melting profile patterns [12].

KRAS and BRAF oncogenes are two genes of interest in cancerous cells’ investigation and their mutational status is important to patient’s cancer outcome. In this context, the sensitive and reliable methods compared and analyzed elsewhere [13]. Common signaling pathways such as KRAS/BRAF/MEK/ERK activated in colorectal cancer (CRC) [14,15]. Hydrolysis of guanosine triphosphate (GTP) molecules has a critical role in inactivation of complex KRAS genes produced by signal transduction protein [16,17]. Mutants of KRAS gene are less sensitive to hydrolysis and this leads to cell proliferation mediated KRAS [17,18]. In CRC patients, KRAS gene mutations were identified about 30-40% [19,20], which KRAS exon 2 mutations are more frequent (almost 90% at codons 12/13 in CRC patients) [21,22]. KRAS activates the cytosolic protein kinase which encodes by BRAF gene [23]. BRAF mutations induced cell propagation by MAPKs signaling cascade [24,25]. BRAF mutation rates in CRC patients estimates approximately 10% and the most common substitution in BRAF gene is V600E in CRC patients [26,27].

Recently, before any specific therapy in CRC patients recommended the screening of KRAS and BRAF mutations as a necessity and due to the presence of some screening methods in this area, the reliable, rapid, and cost-effective diagnostic method is one of research interests [16]. In the current study, our main objective was to validate the performance of HRM technique compared to allele specific PCR (DxS) and Pyrosequencing by samples (n=1000) that originated from colorectal cancer tissues for the detection of KRAS and BRAF mutations in selected subsets.

Material and Methods

Participants

Samples were collected from Iranian mCRC patients who referred to Mehr Hospital, the main referral center for cancerous patients in Tehran, Iran from Feb. 2008 to May 2012 and enrolled in this study. Written consent obtained from each patients and ethical committee of Iran University of Medical Sciences, Tehran, Iran approved ethics of present study. A total of 1000 mCRC FFPE samples included 427 (42.7%) female by the average age of 55 years and 573 (57.3%) male by the average age of 57 years were enrolled (Table 1).

Demographic and Pathological Characteristics

N

%

Sex

Male

573

57.3

Female

427

42.7

Age (y)

≤50

325

32.5

˃50

675

67.5

Tumor differentiation

Well Differentiated

439

43.9

Moderate Differentiated

384

38.4

Poor differentiated

164

16.4

Undifferentiated

13

1.3

Table 1: Demographic characteristics of 1000 mCRC patients.

Formalin-Fixed Paraffin-Embedded (FFPE) tissue DNA extraction

FFPE tissues were manually dissected by block trimming from 10 μm thickness collected in a micro tube for genetic testing and digested by proteinase K at 56 °C for 3 days in a rotating incubator. QIAamp® DNA FFPE Tissue Kit (QIAGEN, Hilden, Germany) used for genomic DNA extraction according to the manufacturer's protocol. NanoDrop ND-1000® (Thermo Fisher Scientific Inc., Waltham, MA, USA) spectrophotometer used for concentration (ng/ul) and purity (OD 260/280nm) quantification of extracted DNA. Then, the extracted DNA was kept at -20 °C before use.

Pyrosequencing

The Qiagen PyroMark KRAS v.2.0 Q96 kit by specific primers used for the amplification of KRAS gene codons 12 and 13. Master mix compounds of 12.5μl PyroMark PCR Master Mix, 2.5μl CoralLoad Concentrate, 1μl PCR Primer KRAS 12/13, 4μl Water (supplied) and 5μl sample DNA (2-10 ng concentration) in a total volume of 25μl. PCR reactions performed on Veriti 96 well Applied Bio System thermal cycler by the heating program: initial de-naturation at 95 °C 15 min, 42 cycles of 95 °C 20 s (denaturation), 53 °C 30 s (annealing), 72 °C 20 s (extension) and one step of final extension at 72 °C for 5 minutes.

The Qiagen PyroMark BRAF kit used for the detection of BRAF mutation according to the manufacturers instructions. Primers for BRAF codon 600 were obtained from the PyroMarkBraf v.2.0 kit. The PyroMark Q96 software was used for sequence analysis.

PCR product confirmation of amplification by agarose gel (Sigma-Aldrich, St. Louis, USA) was recorded. Gel Band Purification Kit (GE Healthcare, Little Chalfont, UK) used for the purification of PCR products. Purified PCR products run on a PyroMark ID Pyrosequencing machine (QIAGEN, Germany) for sequencing reactions and PyroMark Q96 analysis software (QIAGEN, Germany) used for the analysis of electroperograms. All electropherograms were read manually.

Dxs Therascreen

Sequence variation of KRAS oncogene by six aminoacids (Gly > Ala, Asp, Arg, Cys, Ser and Val) on codon 12 and one (Gly > Asp) on codon 13 was investigated using TheraScreen DxS KRAS Mutation Kits KR-21 and KR-22 (QiaGen, Hilden, Germany) according to its recommended internal reaction control and a synthetic control template for the calculation of KRAS mutation degree differences. The LightCycler® Adapt Software v1.1 (Roche Diagnostics, Germany) was used for further analysis. Primers feature were included the 3´ end sequence-specific to mutation and Real-time PCR-Scorpion W primer tags.

TheraScreen K-RAS Mutation Kit version DU001PE used for PCR reactions by LightCyclerW480 II (Roche Applied Science, Penzberg, Germany) according to the instructions. Total reaction volume were 25μl and thermal cycler protocol were included steps: initial denaturation at 95 °C in 4 min, 45 cycle at 95 °C in 30 sec., (denaturation) and 60°C in 1 min (annealing). The fluorescence acquisition at the 60°C step (annealing) performed. Assay components included 19.8μl reaction mix, 0.2μl Taq, and 5μl of sample/control by a total volume of 25μl in each reaction tubes. Light Cycler Analysis Software 1.5.0 SP3 program (Roche Applied Science, Penzberg, Germany) used for reports of the Ct and ΔCt values.

High Resolution Melting (HRM)

HRM method performed for the screening of KRAS mutation. LightCycler® 480 II Real-Time System (Roche Diagnostics, Basel, Switzerland) provided for PCR amplification and HRM. LightCycler® 480 Gene Scanning Software Version 1.5 (Roche diagnostics, Germany) used for data analysis.

PCR reaction performed by the following protocol: forward primer (GCC TGC TGA AAA TGA CTG AA) 1μl and reverse primer (TAT CGT CAA GGC ACT CTT GC) 1μl, ddH2O 10μl, genomic DNA (10 ng/μl) 3μl, HRM master mix (QIAGEN) Mat. NO. 1057636 20µl in a final volume of 35μl. Termocycler program for KRAS gene amplification were as follows: Initial PCR activation step (Pre-amplification) at 95 °C for 5 min by ramp rate 4.4 °C/s, amplification stage included 55 cycles of denaturation at 95 °C for 10 s by ramp rate 4.4 °C/s, annealing 63 °C 30 s by ramp rate 2.2 °C/s, and melting analysis at 63 °C for 5 min by the ramp rate of 4.4 °C/s, 70 °C for 1 s by the ramp rate of 4.4 °C/s, 90 °C continuous fluorescence data acquisition by the ramp rate of 0.02 °C/s and 25 acquisitions per second, then cooling samples after HRM at 40 °C 30 s by the ramp rate of 2.2 °C/s.

For BRAF mutation detection initial PCR activation step (Pre-amplification) at 95 °C for 10 min by the ramp rate of 4.4°C/s, amplification stage included 40 cycles of denaturation at 90 °C 20 s by the ramp rate of 4.4°C/s, Annealing 67 °C 20 s by the ramp rate of 2.2 °C/s, and melting analysis at 72 °C for 20 s by the ramp rate of 4.4°C/s, 70 °C for 1 s by the ramp rate of 4.4 °C/s, 90 °C continuous fluorescence data acquisition by the ramp rate of 0.02 °C/s and 25 acquisitions per second, then cooling samples after HRM at 40 °C 30 s by the ramp rate of 2.2 °C/s.

Results

Mutational status of samples

A total of 1000 CRC samples were used for screening of KRAS and BRAF by HRM, Pyrosequencing and Dxs Therascreen methods. At first, HRM were performed for all of the subjects, the subsequent results were analyzed, and we have found that there were 33.6% (336/1000) KRAS mutants and there were not any BRAF mutants. Among 336 KRAS mutants, 286 (85.1%) were codon 12 mutant and 50 (14.9%) were codon 13 mutant (Table 2). As shown in figure 1, the most common mutation at KRAS codon 12 was Gly12Asp, then Gly12Val, Gly12Ser, Gly12Ala, Gly12Cys and Gly12Arg. The positive KRAS mutant specimens did not contain any BRAF mutation.

Figure 1: Details of detected mutations of KRAS and BRAF.

Clinical And Pathological Characteristics

KRAS Wild Type,

KRAS Mutant, N (%)

N (%)

Total

Codon 12

Codon 13

Sex

Male

402 (60.5%)

171 (50.9%)

143 (83.6%)

28 (16.4%)

Female

262 (39.4%)

165 (49.1%)

143 (86.7%)

22 (13.3%)

Age (y)

≤50

235 (35.4%)

90 (26.8%)

74 (82.3%)

16 (17.7%)

˃50

429 (64.6%)

246 (73.2%)

212 (86.2%)

34 (13.8%)

Tumor

Well Differentiated

265 (39.9%)

173 (51.5%)

77 (44.5%)

96 (55.5%)

Differentiation

Moderate Differentiated

279 (42.0%)

108 (32.1%)

86 (79.6%)

22 (20.4%)

Poor differentiated

109 (16.4%)

54 (16.1%)

39 (72.2%)

15 (27.8%)

Undifferentiated

11 (1.7%)

1 (0.3%)

1 (100.0%)

0 (0.0%)

Total mCRC

1000 patients

664 (66.4%)

336 (33.6%)

286 (85.1%)

50 (14.9%)

Table 2: Mutational status of 1000 mCRC patients.

The Pyrosequencing as the golden standard and another Dxs Therascreen method were performed for checking and were compared with HRM results. However, the Pyrosequencing analyses the mutational status the same as HRM (Figure 2) and the Dxs Therascreen results confirmed them, as well. There were no differences in detection of mutational status in KRAS gene in 33.6% of specimens in codon 12 or 13 and BRAF gene in none of them.

Reliability and sensitivity of HRM

Figure 2: KRAS analysis by Pyrosequencing. (Top electropherogram) Wild type (Normal) - (12Gly-GGT, 13Gly-GGC), (middle and bottom electropherogram) Mutant-KRAS (12Asp-GAT, 12Cys-TGT).

1000 samples were screened to evaluate the reliability and sensitivity of HRM assay. HRM results were compared with pyrosequencing and Dxs Therascreen method. Subsequently, the specificity and sensitivity of HRM were assessed as high in detection of 336 KRAS positive mutant samples and 664 wild types compared with two other methods. BRAF mutation was negative in all 242 KRAS mutant samples. Examples of HRM and melting profiles obtained from tissues carrying mutations of KRAS are shown in Figure 3. In all cases, the HRM is approved by the results of pyrosequencing and Dxs Therascreen. Consequently, the specificity and sensitivity of HRM analysis were 100% (Figure 4).

Figure 3: HRM analysis melting profiles obtained from tissues carrying mutant KRAS.
Figure 4: HRM specificity and sensitivity diagram.

Discussion

Reliable and practicable screening of mutations in known genes would be requested in future clinical practice [28]. Hence, there is noticeably an essential need for rapid and low-cost detection of mutations with high accuracy. Though DNA sequencing is recognized as the golden standard, it is less applicable in clinical screening of genes. This limitation can be explained by high costs and low sensitivity of sequencing [9]. The main purpose of current study was to develop a sensitive test, which makes the rapid detection of hot-spot mutations of KRAS, and BRAF ontogenesis possible in mCRC. HRM has been established for the detection of mutation from various samples, such as frozen tumor samples and archived specimens in the form of formalin fixed paraffin-embedded and methanol-fixed tissues [29]. This method provides a reliable and inexpensive test to carry out mutational screenings of tumor specimens in the clinical practice and diagnostic lab [30,31] . A meta-analysis indicated that the overall values of the sensitivity and specificity of HRM were 0.99 (95% CI 5 0.75-0.82) and 0.99(95% CI 5 0.94-0.98), respectively [29]. In our study, HRM confirms the results of pyrosequencing and Dxs Therascreen in all formalin fixed paraffin-embedded samples and these finding shown 100% sensitivity and specificity of HRM. The results obtained here suggest that the HRM, in comparison with DNA sequencing, is a more applicable technique for detection of the BRAF and KRAS mutations. It is also worth mentioning that one of the few disadvantages of HRM is that it cannot easily distinguish how many mutations are present, or where within the amplified fragment the mutation is positioned. For this, sequencing of the PCR product is essential [32].

Within several investigations, various factors had been testified that might affect the HRM accuracy, although the accuracy of HRM is remarkable [33]. Takano et al. showed that sensitivity increased, when fresh tumor samples were used for HRM, a possible explanation for this event is degeneration of DNA throughout sampling, or the maintenance of the archived samples [34]. Wittwer et al. reported that sensitivity and specificity of HRM for fragments smaller than 400 bp is 100% and they also indicated that sensitivity increased when melt profile contains just one or two melt domains not more [33]. Another study showed that, when the amplicon lengths were between 400 and 1 kb, sensitivity and specificity decreased to 96.1% and 99.4%, respectively [31]. It has been demonstrated that GC content fragments might affect the results of HRM and shown that lower GC content is associated with false negative results [35,36]. The finding of this study supports most of the previous investigation results regarding effectible factors on HRM sensitivity and specificity. Our samples almost were high GC content and short length but not fresh and were formalin fixed paraffin-embedded tissues. However, there again the maintenance conditions of archived samples in our lab was appropriate and not seems that DNA might have been degenerated.

Collectively, current study verified the high sensitivity and specificity of HRM and our results seem to highlight the significance of HRM for precise scanning of KRAS mutations and BRAF screening. It is also possible to state that HRM may be a more attractive technique for the detection of known or unknown somatic mutations of other genes, in comparison with other methods. However, further research is required on this topic. In countries like Iran which costs of test affect the treatment, low cost of accurate HRM assay is the best choice.

Acknowledgments

The authors widely acknowledged the patients and their families for participation in this project. This work was supported by Iran University of Medical Sciences.

References

  1. Simi L, Pratesi N, Vignoli M, Sestini R, Cianchi F, et al. (2008) High-resolution melting analysis for rapid detection of KRAS, BRAF, and PIK3CA gene mutations in colorectal cancer. Am J Clin Pathol 130(2): 247-253.
  2. Walther Z, Ronski K, Wan M, Sklar J (2012) A TaqMan array system for mutation profiling of solid tumors using routine surgical pathology and cytology specimens. J Mol Diagn 14: 704.
  3. Tan YH, Liu Y, Eu KW, Ang PW, Li WQ, et al. (2008) Detection of BRAF V600E mutation by pyrosequencing. Pathology 40(3): 295-298.
  4. Wooster R, Futreal AP, Stratton MR (2006) Sequencing analysis of BRAF mutations in human cancers. Methods Enzymol 407: 218-224.
  5. Morandi L, de Biase D, Visani M, Cesari V, De Maglio G, et al. (2012) Allele specific locked nucleic acid quantitative PCR (ASLNAqPCR): an accurate and cost-effective assay to diagnose and quantify KRAS and BRAF mutation. PloS One 7(4): e36084.
  6. Packham D, Ward RL, Ap Lin V, Hawkins NJ, Hitchins MP (2009) Implementation of novel pyrosequencing assays to screen for common mutations of BRAF and KRAS in a cohort of sporadic colorectal cancers. Diagn Mol Pathol 18(2): 62-71.
  7. Sundstrom M, Edlund K, Lindell M, Glimelius B, Birgisson H, et al. (2010) KRAS analysis in colorectal carcinoma: analytical aspects of Pyrosequencing and allele-specific PCR in clinical practice. BMC Cancer 10: 660.
  8. Fransen K, Klintenas M, Osterstrom A, Dimberg J, Monstein HJ, et al. (2004) Mutation analysis of the BRAF, ARAF and RAF-1 genes in human colorectal adenocarcinomas. Carcinogenesis 25(4): 527-533.
  9. Krypuy M, Newnham GM, Thomas DM, Conron M, Dobrovic A (2006) High resolution melting analysis for the rapid and sensitive detection of mutations in clinical samples: KRAS codon 12 and 13 mutations in non-small cell lung cancer. BMC Cancer 6: 295.
  10. Negru S, Papadopoulou E, Apessos A, Stanculeanu DL, Ciuleanu E, et al. (2014) KRAS, NRAS and BRAF mutations in Greek and Romanian patients with colorectal cancer: a cohort study. BMJ Open 4(5): e004652.
  11. Reed GH, Wittwer CT (2004) Sensitivity and specificity of single-nucleotide polymorphism scanning by high-resolution melting analysis. Clinical chemistry 50(10): 1748-1754.
  12. Boyd EM, Bench AJ, van 't Veer MB, Wright P, Bloxham DM, et al. (2011) High resolution melting analysis for detection of BRAF exon 15 mutations in hairy cell leukaemia and other lymphoid malignancies. Br J Haematol 155(5): 609-612.
  13. Borras E, Jurado I, Hernan I, Gamundi MJ, Dias M, et al. (2011) Clinical pharmacogenomic testing of KRAS, BRAF and EGFR mutations by high resolution melting analysis and ultra-deep pyrosequencing. BMC Cancer 11: 406.
  14. Popovici V, Budinska E, Tejpar S, Weinrich S, Estrella H, et al. (2012) Identification of a poor-prognosis BRAF-mutant-like population of patients with colon cancer. J Clin Oncol 30(12): 1288-1295.
  15. Vakil L, Najafipour R, Rakhshani N, Zamani F, Morakabati A, et al. (2016) Investigation of FIH-1 and SOCS3 expression in KRAS mutant and wild-type patients with colorectal cancer. The journal of the International Society for Oncodevelopmental Biology and Medicine.
  16. Pinto P, Rocha P, Veiga I, Guedes J, Pinheiro M, et al. (2011) Comparison of methodologies for KRAS mutation detection in metastatic colorectal cancer. Cancer Genetics 204(8): 439-446.
  17. Ji H, Wang Z, Perera SA, Li D, Liang MC, et al. (2007) Mutations in BRAF and KRAS converge on activation of the mitogen-activated protein kinase pathway in lung cancer mouse models. Cancer Res 67(10): 4933-4939.
  18. Koochak A, Rakhshani N, Karbalaie Niya MH, Tameshkel FS, Sohrabi MR, et al. (2016) Mutation Analysis of KRAS and BRAF Genes in Metastatic Colorectal Cancer: a First Large Scale Study from Iran. Asian Pac J Cancer Prev 17(2): 603-608.
  19. Andreyev HJ, Norman AR, Cunningham D, Oates J, Dix BR, et al. (2001) Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study. Br J Cancer 85(5): 692-696.
  20. Andreyev HJ, Norman AR, Cunningham D, Oates JR, Clarke PA (1998) Kirsten ras mutations in patients with colorectal cancer: the multicenter "RASCAL" study. J Natl Cancer Inst 90(9): 675-684.
  21. Janakiraman M, Vakiani E, Zeng Z, Pratilas CA, Taylor BS, et al. (2010) Genomic and biological characterization of exon 4 KRAS mutations in human cancer. Cancer Res 70(14): 5901-5911.
  22. De Roock W, De Vriendt V, Normanno N, Ciardiello F, Tejpar S (2011) KRAS, BRAF, PIK3CA, and PTEN mutations: implications for targeted therapies in metastatic colorectal cancer. Lancet Oncol 12(6): 594-603.
  23. Roth AD, Tejpar S, Delorenzi M, Yan P, Fiocca R, et al. (2010) Prognostic role of KRAS and BRAF in stage II and III resected colon cancer: results of the translational study on the PETACC-3, EORTC 40993, SAKK 60-00 trial. J Clin Oncol 28(3): 466-474.
  24. Guedes JG, Veiga I, Rocha P, Pinto P, Pinto C, et al. (2013) High resolution melting analysis of KRAS, BRAF and PIK3CA in KRAS exon 2 wild-type metastatic colorectal cancer. BMC Cancer 13: 169.
  25. Allegra CJ, Jessup JM, Somerfield MR, Hamilton SR, Hammond EH, et al. (2009) American Society of Clinical Oncology provisional clinical opinion: testing for KRAS gene mutations in patients with metastatic colorectal carcinoma to predict response to anti-epidermal growth factor receptor monoclonal antibody therapy. J Clin Oncol 27(12): 2091-2096.
  26. Minoo P, Moyer MP, Jass JR (2007) Role of BRAF-V600E in the serrated pathway of colorectal tumourigenesis. J Pathol 212(2): 124-133.
  27. Di Nicolantonio F, Martini M, Molinari F, Sartore-Bianchi A, Arena S, et al. (2008) Wild-type BRAF is required for response to panitumumab or cetuximab in metastatic colorectal cancer. Chin J Cancer Res 26(35): 5705-5712.
  28. Katsanis SH, Katsanis N (2013) Molecular genetic testing and the future of clinical genomics. Nat Rev Genet 14(6): 415-426.
  29. Chen D, Wang YY, Chuai ZR, Huang JF, Wang YX, et al. (2014) High-resolution melting analysis for accurate detection of BRAF mutations: a systematic review and meta-analysis. Sci Rep 4: 4168.
  30. Li BS, Wang XY, Xu AG, Ma FL, Ma QY, et al. (2012) High-resolution melting assay (HRMA) is a simple and sensitive stool-based DNA Test for the detection of mutations in colorectal neoplasms. Clin Colorectal Cancer 11(4): 280-290.
  31. Montgomery JL, Sanford LN, Wittwer CT (2010) High-resolution DNA melting analysis in clinical research and diagnostics. Expert Rev Mol Diagn 10(2): 219-240.
  32. Chateigner-Boutin A-L, Small I (2007) A rapid high-throughput method for the detection and quantification of RNA editing based on high-resolution melting of amplicons. Nucleic Acids Res 35(17): e114.
  33. Wittwer CT (2009) High-resolution DNA melting analysis: advancements and limitations. Hum Mutat 30(6): 857-859.
  34. Takano T, Ohe Y, Tsuta K, Fukui T, Sakamoto H, et al. (2007) Epidermal growth factor receptor mutation detection using high-resolution melting analysis predicts outcomes in patients with advanced non small cell lung cancer treated with gefitinib. ClinCancerRes 13(18 Pt 1): 5385-5390.
  35. Mader E, Lukas B, Novak J (2008) A strategy to setup codominant microsatellite analysis for high-resolution-melting-curve-analysis (HRM). BMC genetics 9: 69.
  36. Taylor CF (2009) Mutation scanning using high-resolution melting. Biochem Soc Trans 37(Pt 2): 433-437.
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