Identification of protamine 1 as a novel cancer-testis antigen in early chronic lymphocytic leukaemia.

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Identification of protamine 1 as a novel cancer-testis antigen in early chronic

lymphocytic leukaemia.

Farouk Meklat, Yana Zhang, Masum Shahriar, Sharif U Ahmed, Wei Li, Nikolaos

Voukkalis, Zhiqing Wang, Jian Zhang, Suhkrob Mastulov, Jewell,

kouros, and Seah H Lim

Br J Haematol, November 22, 2008; .

Cancer Research Program, Harrington Regional Medical Center, Inc., Amarillo, TX,

USA.

Early chronic lymphocytic leukaemia (CLL) is an ideal disease for immunotherapy.

We previously showed that SEMG 1 is a cancer-testis (CT) antigen in CLL. In this

study, SEMG 1 was applied as the bait in a yeast two-hybrid system of a

testicular cDNA library. Seven clones were isolated and Protamine (Prm) 1 was

identified as a novel CT antigen in early CLL. PRM1 transcripts were detected in

11/41 (26.8%) patients. Prm 1 protein was also expressed but heterogeneously

within individual patients. Of the 11 patients expressing Prm 1, four expressed

Zap 70 protein and seven did not. These results, therefore, indicate that Prm 1

could potentially be a suitable target for the design of tumour vaccine for

patients with early CLL, including for those with poor risk CLL. High titres of

Prm 1 IgG antibodies could be detected in 20 of these 41 CLL patients but not in

any of the 20 healthy donors (P = 0.0001), suggesting the presence of Prm

1-reactive immune responses within the immune repertoire of patients with early

CLL. Further work is warranted, especially in approaches to upregulate Prm 1

expression, and to determine the role of Prm 1 as an immunotherapeutic target

for early CLL.

PMID: 19036087