Identification of metastasis-associated alternatively spliced variants of CD99 in clear cell renal cell carcinoma tissues

Abstract

Objective:To identify the metastasis-associated splice variants of CD99 and investigate the mRNA expression of the splice variants in clear cell renal cell carcinoma(ccRCC) tissues,so as to investigate its relationship with the initiation and progression of ccRCC.Methods: Alternative Splicing Database was used to predict the splice variants of CD99.The six predicted splice variants of CD99 were identified in the metastatic tissues,primary ccRCCs and normal tissues adjacent to cancer by using self-designed primer sets,and were cloned into vectors and sequenced.The mRNA expression of CD99 type Ⅰ,CD99 type Ⅱ,and CD99-Ⅲ were detected in 9 metastatic tissues and their corresponding cancer tissues,21 primary ccRCCs and normal tissues adjacent to cancer by RT-PCR.Results: A new isoform of CD99(CD99-Ⅲ) was identified,which was detected in 8 of the 9 metastatic tissues,a ratio significantly higher than that in the primary ccRCCs without metastasis(10 out of 21,P0.05).The results revealed that the transcripts of CD99 type Ⅰ was present in all of the ccRCC specimens tested;CD99 type Ⅱ was detected in 6 of 9 metastatic corresponding primary cancer tissues,a ratio significantly higher than that in cancer tissues without metastasis(3 out of 21,P=0.008).Conclusion: CD99 type Ⅱ and CD99-Ⅲ,a novel splice variant of CD99,may be associated with the initiation and progression of ccRCC.