Mutational analysis of the RAS/RAF/MEK/ERK signaling pathway in 260 Han Chinese patients with cervical carcinoma

Abstract

Prevalent mutations in the mitogen-activated protein kinase 1 (MAPK1)/extracellular signal-regulated kinase 2 (ERK2) pathway have been identified in cervical squamous cell carcinoma in a large-scale genome sequencing effort. Furthermore, mutations in the rat sarcoma viral oncogene homolog (RAS)/Raf/Mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway have also been revealed to have important roles in the pathogenesis of human cancer. However, whether the potential hotspot mutations in ERK2 and other components of the RAS/RAF/MEK/ERK signaling pathway also exist in Chinese patients with cervical carcinoma remains to be elucidated. In the present study, a total of 260 patients with cervical carcinoma of distinct subtypes were analyzed for the presence of potential hotspot mutations in the RAS/RAF/MEK/ERK signaling pathway. No ERK2 mutations were detected in these samples; however, Kirsten RAS (KRAS) p.G12D (c.35G>A) mutation was identified in 2/26 (7.7%) cervical adenocarcinoma cases, including 1/20 cervical mucinous adenocarcinoma and 1/6 cervical endometrioid carcinoma cases. In addition, no mutations in the ERK1, neuroblastoma RAS, Harvey RAS or B-Raf proto-oncogene serine/threonine kinase genes were detected in the present study. These results indicated that ethnic differences may be a primary reason for the discrepancy in ERK2 mutation frequencies between the current study and previous studies. Furthermore, mutation in the KRAS gene, but not other genes in the RAS/RAF/MEK/ERK signaling pathway, may have an active role in the pathogenesis of cervical carcinoma.

Keywords: cervical carcinoma; mitogen-activated protein kinase 1; mutation; rat sarcoma viral oncogene homolog/Raf/mitogen-activated protein kinase activated kinase/mitogen-activated protein kinase 1 signaling pathway.

Figure 1.

Protein sequence homology analysis of ERK2 and ERK1. Human ERK2 (NP_002736) and ERK1 (NP_002737) protein sequences were obtained from the GenBank database, and the amino acid sequences were aligned with DNASTAR® Lasergene version 7.2 software, according to the software manuals. The 317th-327th amino acids of ERK2 and 334th-344th amino acids from ERK1 are displayed here. ERK, mitogen-activated protein kinase.

Figure 2.

Representative sequencing electropherograms of the potential mutation site in ERK2 p.E322, ERK1 p.E339, KRAS (p.G13 and p.Q61), NRAS (p.G12, p.G13 and p.Q61), HRAS (p.G12, p.G13 and p.Q61) and BRAF (p.V600E); the arrows refer to the wild type sequence with potential hotspot mutations. ERK, mitogen-activated protein kinase; KRAS, Kirsten rat sarcoma viral oncogene homolog; NRAS, neuroblastoma RAS; HRAS, Harvey RAS; BRAF, B-Raf proto-oncogene serine/threonine kinase.

Figure 3.

Representative sequencing electropherogram of KRAS p.G12D (c.35G>A) mutation; the arrow refers to the location of the mutation. KRAS, Kirsten rat sarcoma viral oncogene homolog.