PURPOSE: The purpose is to compare the molecular characteristics of serrated adenomas (SAs) with those of conventional adenomas (CADs) and hyperplastic polyps (HPs). EXPERIMENTAL DESIGN: We evaluated the proliferative activity and molecular alterations in 47 SAs (25 pure-type and 22 mixed-type), 71 CADs, and 23 HPs. RESULTS: The proliferative activity of SAs, as evaluated by Ki-67 expression, was intermediate between CADs and HPs. There was no significant difference in the incidence of KRAS or p53 mutations between the three histological groups. In the microsatellite instability (MSI) analysis, 21% of SAs (9 of 43) showed MSI at two or more loci (MSI-H); corresponding values were 5% of CADs (3 of 64) and 8% of HPs (1 of 13; SAs versus CADs, P = 0.0125). MSI-H was more likely to be found in pure-type SAs (36%; 8 of 22) than in mixed-type SAs (5%; 1 of 21; P = 0.0212). Loss of hMLH-1 expression was found in 8 of 9 SAs with MSI-H. The incidence of BRAF or KRAS mutations was 36 and 15% of SAs, respectively; the combined incidence of BRAF and KRAS mutations occurred in 49% of SAs. However, there was no significant difference in the incidence of BRAF or KRAS mutations between SAs with and without MSI-H. CONCLUSIONS: Genetic instability is more frequently implicated in the tumorigenesis of SAs, especially pure-type SAs, than in that of CADs. In contrast, activation of the Ras/Raf/MEK/MAP kinase cascade by BRAF or KRAS mutation, independently of the genetic instability, may be associated with the progression of about half of SAs.
PURPOSE: The purpose is to compare the molecular characteristics of serrated adenomas (SAs) with those of conventional adenomas (CADs) and hyperplastic polyps (HPs). EXPERIMENTAL DESIGN: We evaluated the proliferative activity and molecular alterations in 47 SAs (25 pure-type and 22 mixed-type), 71 CADs, and 23 HPs. RESULTS: The proliferative activity of SAs, as evaluated by Ki-67 expression, was intermediate between CADs and HPs. There was no significant difference in the incidence of KRAS or p53 mutations between the three histological groups. In the microsatellite instability (MSI) analysis, 21% of SAs (9 of 43) showed MSI at two or more loci (MSI-H); corresponding values were 5% of CADs (3 of 64) and 8% of HPs (1 of 13; SAs versus CADs, P = 0.0125). MSI-H was more likely to be found in pure-type SAs (36%; 8 of 22) than in mixed-type SAs (5%; 1 of 21; P = 0.0212). Loss of hMLH-1 expression was found in 8 of 9 SAs with MSI-H. The incidence of BRAF or KRAS mutations was 36 and 15% of SAs, respectively; the combined incidence of BRAF and KRAS mutations occurred in 49% of SAs. However, there was no significant difference in the incidence of BRAF or KRAS mutations between SAs with and without MSI-H. CONCLUSIONS: Genetic instability is more frequently implicated in the tumorigenesis of SAs, especially pure-type SAs, than in that of CADs. In contrast, activation of the Ras/Raf/MEK/MAP kinase cascade by BRAF or KRAS mutation, independently of the genetic instability, may be associated with the progression of about half of SAs.
Authors: Oscar Murcia; Miriam Juárez; Eva Hernández-Illán; Cecilia Egoavil; Mar Giner-Calabuig; María Rodríguez-Soler; Rodrigo Jover Journal: World J Gastroenterol Date: 2016-04-07 Impact factor: 5.742
Authors: Fernando Martínez; Carlos Fernández-Martos; María Jesús Quintana; Antoni Castells; Antonio Llombart; Francisco Ińiguez; Vicente Guillem; Francisco Dasí Journal: Clin Transl Oncol Date: 2011-09 Impact factor: 3.405
Authors: Maria Simona Pino; Mari Mino-Kenudson; Bernadette Mandes Wildemore; Aniruddha Ganguly; Julie Batten; Isabella Sperduti; Anthony John Iafrate; Daniel C Chung Journal: J Mol Diagn Date: 2009-03-26 Impact factor: 5.568