C-kit expression in dedifferentiated and well-differentiated liposarcomas; immunohistochemistry and genetic analysis.
BACKGROUND
c-kit expression by immunohistochemistry has been utilized to identify cancer patients who can be treated with imatinib-mesylate. In gastrointestinal stromal tumors (GISTs), an activating mutation in c-kit predicts treatment response; its presence in other soft tissue tumors is unexplored.


METHODS
We evaluated seven cases of dedifferentiated liposarcomas (DDLS) and compared those with seven well-differentiated liposarcomas (WDLS). Immunohistochemical staining for c-kit was performed using a polyclonal antibody. Using PCR, exons 9, 10-11, 12-13 and 17 of c-kit were amplified and direct DNA sequencing performed.


RESULTS
Two out of 7 (30%) DDLS showed focal weak immunoreactivity with c-kit; no (0%) WDLS stained with c-kit. Seven out of 7 (100%) DDLS showed an allelic variation in exon 10, with a single base pair substitution (A >C) at codon 541; 3/7 (43%) WDLS showed the same change.


CONCLUSIONS
c-kit immunoreactivity did not correlate with the change in DNA sequence; DDLS showed a consistent allelic variation in c-kit that may have significant prognostic, diagnostic and therapeutic implications.
Tayal
Shalini
S
Department of Pathology, University of Colorado Health Sciences Center, Denver, Colorado, USA.
Classen
Elizabeth
E
Bemis
Lynne
L
Robinson
William A
WA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002454:Cell Differentiation / Q000502:physiology; D005091:Exons; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008080:Liposarcoma / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis* / Q000235:genetics; D012186:Retroperitoneal Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D017422:Sequence Analysis, DNA
D019009:Proto-Oncogene Proteins c-kit