Procholecystokinin as marker of human Ewing sarcomas.
OBJECTIVE
Ewing sarcoma is a rapidly growing mesenchymal tumor in young adults. Although it was shown previously to express the cholecystokinin (CCK) gene, it is unknown whether CCK gene expression is detectable at protein level in Ewing sarcoma tumor cell lines, in tumor tissue, and in plasma from Ewing sarcoma patients, and, if so, whether CCK peptides might play a role as tumor markers.


METHODS
CCK gene expression was evaluated with in situ hybridization or reverse transcription-PCR in tumor tissue. CCK precursors and bioactive CCK were measured with specific RIAs in tumor tissue, in cell culture medium, and in plasma of Ewing sarcoma patients before and after chemotherapy as well as after tumor recurrence.


RESULTS
CCK mRNA was identified in 12 Ewing sarcoma biopsies sampled in two series and in four Ewing sarcoma cell lines but not in unrelated neoplasia. Immunoreactive proCCK was identified in the culturing medium of all Ewing sarcoma cell lines but not in the media from unrelated tumor cell lines. Moreover, in plasma from Ewing sarcoma patients, precursors and mature forms of CCK, in particular proCCK, were detected; several fold elevation of the total proCCK product was found in plasma from patients before treatment and after tumor recurrence, whereas successful chemotherapy reduced proCCK to basal concentrations. Plasma concentrations of proCCK paralleled the respective tumor size.


CONCLUSIONS
This is the first study that consistently documents an altered CCK metabolism in human cancer; Ewing sarcomas synthesize and secrete proCCK that can be identified in plasma as circulating tumor marker.
Reubi
Jean Claude
JC
Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Switzerland.
Koefoed
Pernille
P
Hansen
Thomas von O
Tv
Stauffer
Edouard
E
Rauch
Daniel
D
Nielsen
Finn C
FC
Rehfeld
Jens F
JF
D014408:Biomarkers, Tumor / Q000097:blood; D001859:Bone Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D045744:Cell Line, Tumor; D002766:Cholecystokinin / Q000097:blood / Q000235:genetics*; D006801:Humans; D011498:Protein Precursors / Q000097:blood / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012512:Sarcoma, Ewing / Q000097:blood / Q000175:diagnosis* / Q000235:genetics
D014408:Biomarkers, Tumor; D011498:Protein Precursors; D012333:RNA, Messenger; C060249:procholecystokinin; D002766:Cholecystokinin