A novel exon 15-deleted, splicing variant of Slit2 shows potential for growth inhibition in addition to invasion inhibition in lung cancer.
BACKGROUND
The axon guidance cue molecule Slit2 has been shown to suppress cancer cell invasion. However, the role of Slit2 in growth inhibition is still controversial. The authors identified a novel exon 15 (AKEQYFIP)-deleted slit2, located at the end of the second leucine-rich repeat (LRR2). Because LRR2 interacts with Robo1 receptor to inhibit invasion, they hypothesized that exon 15 plays an important role in modulating Slit2 function.


METHODS
Slit2 expression was assessed via microarray analysis in 27 lung adenocarcinomas. Exon 15-deleted slit2 (slit2-ΔE15) and exon 15-containing slit2 (slit2-WT) were cloned and expressed in the CL1-5 lung cancer cell line. The effect of exon 15 on Slit2-mediated cell growth was evaluated by a xenografted model and in vitro cell growth assays. The effect of exon 15 on Slit2-mediated invasion was analyzed with a modified Boyden chamber in vitro.


RESULTS
Tumor growth from CL1-5/Slit2-WT cells was comparable to that from CL1-5 cells bearing empty vector. However, tumor size from CL1-5/Slit2-ΔE15 cells was much smaller than that from Slit2-WT cells or vector control cells in the xenografted model. In vitro analyses demonstrated that Slit2-WT inhibits invasion of CL1-5 cells. In addition to inhibiting invasion, Slit2-ΔE15 greatly suppresses cell growth.


CONCLUSIONS
The data demonstrated that exon 15 modulates Slit2 function in growth inhibition of lung cancer cells. Because slit2-ΔE15 splice variant is present in low invasive cancer cells and nontumor lung tissues, loss of this splice variant is an important event in tumor progression and invasion.
Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC.
Yu-Ying
YY
Lin
Chun-Hung
CH
Yang
Gwo-Tarng
GT
Sheu
Chi-Ying F
CY
Huang
Yu-Chung
YC
Wu
Shu-Ming
SM
Chuang
Ming-Ji
MJ
Fann
Han
H
Chang
Huei
H
Lee
Jinghua Tsai
JT
Chang
D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology*; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002455:Cell Division / Q000235:genetics*; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned; D017931:DNA Primers; D005091:Exons; D005434:Flow Cytometry; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology*; D051379:Mice; D016513:Mice, SCID; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012326:RNA Splicing; D034741:RNA, Small Interfering; D000098552:Slit Homolog 2 Protein
D017077:Culture Media, Conditioned; D017931:DNA Primers; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D000098552:Slit Homolog 2 Protein