Possible Role of Semaphorin 3F, a Candidate Tumor Suppressor Gene at 3p21.3, in p53-Regulated Tumor Angiogenesis Suppression

Manabu Futamura,Yoshiko Masuda,Shiho Ohnishi,Hiroki Kamino,Hirofumi Arakawa,Noriaki Kitamura,Yasuyuki Nakamura,Yuji Miyamoto

doi:10.1158/0008-5472.can-06-2485

Abstract

Although the regulation of tumor angiogenesis is believed to be one of the core functions of p53, the mechanism still remains to be elucidated. Here, we report that semaphorin 3F (SEMA3F), an axon guidance molecule, is involved in p53-regulated antiangiogenesis. The expression level of SEMA3F mRNA was increased by both exogenous and endogenous p53. Chromatin immunoprecipitation assay indicated that a potent p53-binding sequence in intron 1 of SEMA3F interacts with p53 and that it has a p53-responsive transcriptional activity. Overexpression of SEMA3F inhibited in vitro cell growth of the lung cancer cell line H1299. In nude mice assay, the size of the H1299 tumors expressing SEMA3F was much smaller, and they showed lesser number of blood vessels as compared with the control tumors. Moreover, tumors derived from the p53-knockdown colorectal cancer cell line LS174T displayed a remarkable enhancement of tumor vessel formation as compared with control tumors containing normal levels of p53. The expression levels of SEMA3F and neuropilin-2 (NRP2), the functional receptor for SEMA3F, in p53-knockdown LS174T tumors were lower than those in the control tumors. Adenovirus-mediated SEMA3F gene transfer induced the remarkable in vitro growth suppression of the stable transformant of H1299 cells, which express high levels of NRP2. These results suggest that p53 negatively regulates tumor vessel formation and cell growth via the SEMA3F-NRP2 pathway.

Highlights

The tumor suppressor p53 prevents malignant transformation when the cells suffer cellular stresses including severe DNA damage [1]
We first carried out Northern blot analysis of the semaphorin 3F (SEMA3F) gene. mRNAs were subjected to Northern blot analysis, which were obtained at the indicated time after infection from the HepG2 cells, a hepatocellular carcinoma cell line, infected with adenovirus p53 (Ad-p53) or adenovirus EGFP (Ad-EGFP)
SEMA3F was initially identified as a candidate tumor suppressor gene at chromosome 3p21.3, the causative point mutations in the SEMA3F gene are very rare in human cancers [17,18,19]

Summary

Introduction

The tumor suppressor p53 prevents malignant transformation when the cells suffer cellular stresses including severe DNA damage [1]. P53 is known as a ‘‘guardian of human genome’’ [2]. P53 is mutated in >50% of all human cancers, emphasizing its essential role in tumorigenesis in any of the human cancers. Numerous studies on p53 have been conducted far, and several findings have been reported. These efforts have provided concrete evidence for the following functions of p53. The p53 gene encodes a transcription factor that binds to a specific sequence of its downstream target gene [3].

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