MSH2 missense mutations and HNPCC syndrome: pathogenicity assessment in a human expression system.
Hereditary Non-Polyposis Colorectal Cancer (HNPCC) is associated with germline mutations in one of several MisMatch Repair (MMR) genes. An increasing proportion (20-25%) of the reported MSH2 variants consists of single amino-acid substitution with uncertain disease-causing significance. The present study was undertaken to functionally characterize 3 MSH2 nontruncating variants: p.Gly162Arg (c.484G>C), p.Asp167His (c.499G>C) and p.Arg359Ser (c.1077A>T). Missense alterations, were assessed in a human system for expression/stability and for the ability to heterodimerize with MSH6 and correctly localize into the nucleus. Functional assays results were correlated with clinical and genetic features indicative of HNPCC as MicroSatellite-Instability (MSI), abnormalities of MMR gene expression in tumour tissue (IHC) and familial history. p.Gly162Arg and p.Arg359Ser variants showed a clearly decreased expression level of the MutSá complex and were associated with an abnormal subcellular localization pattern, which can be suggestive of an incorrect MSH2/MSH6 heterodimerization. Functional analysis results were supported by MSI and IHC data and by familial cancer history. The subcellular localization assay, performed in a human expression system, classifies as pathogenetic two MSH2 nontruncating alterations providing a useful tool in genetic testing programs.
Belvederesi
Laura
L
Centro Regionale di Genetica Oncologica - Oncologia Medica, Università Politecnica delle Marche, Ancona, Italy. l.belvederesi@univpm.it
Bianchi
Francesca
F
Galizia
Eva
E
Loretelli
Cristian
C
Bracci
Raffaella
R
Catalani
Romina
R
Amati
Monica
M
Cellerino
Riccardo
R
D000328:Adult; D019943:Amino Acid Substitution; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D008875:Middle Aged; D051718:MutS Homolog 2 Protein / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D010641:Phenotype; D016415:Sequence Alignment
D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein