Significance of RAS mutations in pulmonary metastases of patients with colorectal cancer
RAS/BRAF mutations of colorectal cancer (CRC) play a crucial role in carcinogenesis and cancer progression and need to be considered for the therapeutic strategy choice. We used next-generation-sequencing (NGS) technology to assess RAS/BRAF mutation differences between primary CRC and corresponding pulmonary metastases (PMs).
We examined the mutation statuses of the KRAS 12/13/61/146, NRAS 12/13/61/146, and BRAF 600 codons in genomic DNA from fresh-frozen or formalin-fixed paraffin-embedded tissues derived from 34 primary lesions and 52 corresponding PMs from 36 patients with CRC.
We found RAS mutations in 76% (26/34) of primary CRC lesions and in 86% (31/36) of PMs. While 27% (7/26) of the primary CRC RAS mutations were heterogeneous, all the RAS mutations in PMs were homogeneous. Of the mutations in PMs, 71% (22/31) were KRAS G>A transitions, of which 82% (18/22) were KRAS G12D or G13D. The RAS mutation discordance between primary tumors and PMs was 12.1% (4/33). RAS mutations with the same genotyping were detected in all synchronous and metachronous PMs from 9 patients. We found no BRAF mutations in either primary or pulmonary tissues.
Our NGS analysis suggests that RAS mutations of PM of patients with CRC are more common than initially thought. The presence of KRAS mutations in CRC specimens, especially G12D or G13D mutations, seems to promote PM formation.
KeywordsRat sarcoma viral oncogene homolog (RAS) Pulmonary metastasis Colorectal cancer
We are grateful for the experimental support we received from Mr. Tatsuya Yamazaki, Mr. Masaki Shinohara, and Ms. Yuriha Iwata. We would also like to thank RIKEN GeNAS for amplicon sequencing analyses with the Illumina HiSeq2500 sequencer.
This work was supported by the Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science; Grant numbers 22590516 and 19390359, by the subsidy of expenses of the Minister of Economy, Trade and Industry, Japan for small business support, and by a Research Grant from the Japanese Ministry of Education, Culture, Sports, Science and Technology to the RIKEN Center for Life Science Technologies.
Compliance with ethical standards
Conflict of interest
The authors have no conflicts of interest directly relevant to the content of this article.
- 2.De Roock W, Claes B, Bernasconi D et al (2010) Effects of KRAS, BRAF, NRAS, and PIK3CA mutations on the efficacy of cetuximab plus chemotherapy in chemotherapy-refractory metastatic colorectal cancer: a retrospective consortium analysis. Lancet Oncol 11(8):753–762. https://doi.org/10.1016/S1470-2045(10)70130-3 CrossRefPubMedGoogle Scholar
- 3.Heinemann V, von Weikersthal LF, Decker T et al (2014) FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab as first-line treatment for patients with metastatic colorectal cancer (FIRE-3): a randomised, open-label, phase 3 trial. Lancet Oncol 15(10):1065–1075. https://doi.org/10.1016/S1470-2045(14)70330-4 CrossRefPubMedGoogle Scholar
- 6.Gao J, Wu H, Wang L et al (2016) Validation of targeted next-generation sequencing for RAS mutation detection in FFPE colorectal cancer tissues: comparison with Sanger sequencing and ARMS-Scorpion real-time PCR. BMJ Open 6(1):e009532. https://doi.org/10.1136/bmjopen-2015-009532 CrossRefPubMedPubMedCentralGoogle Scholar
- 7.Altimari A, de Biase D, De Maglio G et al (2013) 454 next generation-sequencing outperforms allele-specific PCR, Sanger sequencing, and pyrosequencing for routine KRAS mutation analysis of formalin-fixed, paraffin-embedded samples. Onco Targets Ther 6:1057–1064. https://doi.org/10.2147/OTT.S42369 CrossRefPubMedPubMedCentralGoogle Scholar
- 27.Kadota K, Yeh YC, D'Angelo SP et al (2014) Associations between mutations and histologic patterns of mucin in lung adenocarcinoma: invasive mucinous pattern and extracellular mucin are associated with KRAS mutation. Am J Surg Pathol 38(8):1118–1127. https://doi.org/10.1097/PAS.0000000000000246 CrossRefPubMedPubMedCentralGoogle Scholar