Semaphorin 3A upregulates FOXO 3a-dependent MelCAM expression leading to attenuation of breast tumor growth and angiogenesis

Abstract

Semaphorin 3A (Sema 3A), a member of semaphorin family, serves as a guidance clue during embryonic development and is known as a candidate tumor suppressor that attenuates breast tumor progression by binding with its co-receptor, neuropilin-1 (NRP-1). However, the underlying mechanism by which Sema 3A suppresses breast tumor growth is still unexplored. In this study, we report that Sema 3A regulates phosphorylation and nuclear translocation of phosphatase and tensin homolog (PTEN) and FOXO 3a. Moreover, Sema 3A controls NRP-1-mediated PTEN-dependent FOXO 3a activation. Overexpression of PTEN and FOXO 3a enhances Sema 3A-induced attenuation of breast cancer cell migration. Chromatin immunoprecipitation and electrophoretic mobility shift assay data revealed that FOXO 3a regulates MelCAM at the transcriptional level. Furthermore, Sema 3A induces NRP-1-mediated MelCAM expression through PTEN and FOXO 3a. The data also showed that vascular endothelial growth factor-induced angiogenesis is inhibited by Sema 3A. Loss of or gain in function study revealed that Sema 3A modulates phosphorylation of PTEN and FOXO 3a and expression of MelCAM, leading to suppression of tumor growth and angiogenesis using in vivo mice model. Clinical specimen analysis revealed that reduced expression of Sema 3A and p-PTEN are correlated with enhanced breast cancer progression, further strengthening our in vitro and in vivo findings. Correlation of relapse-free survival of breast cancer patients (n=2878) with expression levels of Sema 3A, NRP-1, FOXO 3a and MelCAM were studied by Kaplan-Meier analysis. Statistical analysis revealed a close association between reduced expression of Sema 3A and MelCAM with that of poor patient's survival. Our study demonstrated a novel mechanism of regulation of tumor suppression by Sema 3A in coordination with a chain of tumor-suppressor genes, which in turn inhibits breast cancer cell migration, tumor growth and angiogenesis.

The role of the semaphorins in cancer

“…Overexpression of PTEN and FOXO-3a enhances sema3A expression resulting in inhibition of breast cancer cells migration. 140 In agreement, it was reported that down regulation of sema3A expression by High mobility group box 1 (HMGB1), a chromatin-associated protein that aids in transcription and DNA repair that binds to the semaphorin 3A genomic locus and inhibits its expression, and as a result increases the migration of tumor cells. 141 Sema3A was also found to enhance the anti-angiogenic effects of VEGF receptor inhibitors such as DC101 and sunitinib.…”

Stilbenoid‐Mediated Epigenetic Activation of Semaphorin 3A in Breast Cancer Cells Involves Changes in Dynamic Interactions of DNA with DNMT3A and NF1C Transcription Factor

“…One of the five genes, SEMA3A , was previously shown to exert a tumor suppressor function in breast cancer. One study reported that SEMA3A regulates phosphorylation of phosphatase and tensin homolog, which in turn activates a chain of TSGs to inhibit breast cancer growth, invasiveness and angiogenic capacity . Another study demonstrated a role for SEMA3A in proliferative control of tumor‐associated macrophages .…”

“…Among all genes containing CpG loci hypomethylated upon exposure to stilbenoids, we identified a group of 113 genes that lose methylation in both lowly MCF10CA1h and highly MCF10CA1a invasive breast cancer cells, and are associated with functions attenuating cancerous properties. One of the highest differences was located within SEMA3A , a gene found to have a potential tumor suppressor role in breast cancer . DNA hypomethylation of SEMA3A promoter as confirmed quantitatively by pyrosequencing coincided with increase in gene expression upon exposure to stilbenoids.…”

Guidance Molecule SEMA3A Restricts Tumor Growth by Differentially Regulating the Proliferation of Tumor-Associated Macrophages

“…SEMA3A expression is downregulated with the increasing degree of malignancy in human breast cancer SEMA3A expression is downregulated in various human cancers, including epithelial ovarian, breast, gastric, and non-small cell lung cancer compared with the respective normal tissue (20)(21)(22)(23). Immunohistochemical staining of 83 breast cancer patient samples with varying grades of malignancy (grade I and III ductal breast cancer accounted for 39 patient samples) revealed that SEMA3A expression is significantly downregulated in grade III ductal breast carcinoma compared with grade I (Fig.…”