The spermatozoa protein, SLLP1, is a novel cancer-testis antigen in hematologic malignancies.
OBJECTIVE
Neoplastic cells often aberrantly express normal testicular proteins. Because these proteins have a very restricted normal tissue expression, they may be suitable targets for immunotherapy. SLLP1 is an intra-acrosomal, nonbacteriolytic, c lysozyme-like protein recently isolated from human spermatozoa. In this study, we determined whether SLLP1 is a novel cancer-testis antigen in hematologic malignancies


METHODS
SLLP1 expression in hematologic tumor cells and normal tissues was determined using a combination of reverse transcription-PCR, real-time PCR, and Western blot analysis. The presence of antibodies against SLLP1 was determined by ELISA analysis.


RESULTS
SLLP1 was aberrantly expressed in the tumor cells from 2 of 9 acute myeloid leukemia, 3 of 11 chronic lymphocytic leukemia, 4 of 14 chronic myeloid leukemia, and 6 of 17 multiple myeloma. In contrast, they were not detected in corresponding specimens from any healthy donors. SLLP1 exhibited a very restricted normal tissue expression, being found only in testis/spermatozoa. SLLP1 was expressed in some tumor cells at a level of >25%. High titer IgG antibodies against SLLP1 were also detected in the sera of some of these patients.


CONCLUSIONS
SLLP1 is a novel cancer-testis antigen in hematologic malignancies and is capable of eliciting B-cell immune responses in vivo in cancer-bearing individuals. Our results, therefore, support SLLP1 as a protein target appropriate for additional in vitro study to define its suitability for immunotherapy.
Division of Hematology and Oncology, Texas Tech University Health Sciences Center, Amarillo, Texas 79106, USA.
Zhiqing
Z
Wang
Yana
Y
Zhang
Arabinda
A
Mandal
Jian
J
Zhang
Francis J
FJ
Giles
John C
JC
Herr
Seah H
SH
Lim
D000951:Antigens, Neoplasm / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019337:Hematologic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007519:Isoantigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020014:K562 Cells; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029589:Seminal Plasma Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*
D000951:Antigens, Neoplasm; D007074:Immunoglobulin G; D007519:Isoantigens; D012333:RNA, Messenger; D011994:Recombinant Proteins; C490560:SPACA3 protein, human; D029589:Seminal Plasma Proteins