Targeting gastrin-releasing peptide as a new approach to treat aggressive refractory neuroblastomas

Abstract

Background The overall survival for neuroblastoma remains dismal, largely in part, due to emergence of resistance to chemotherapeutic drugs. We have demonstrated that gastrin-releasing peptide (GRP), a gut peptide secreted by neuroblastoma, act as an autocrine growth factor. We hypothesized that knockdown of GRP will induce apoptosis in neuroblastoma cells to potentiate the cytotoxic effects of chemotherapeutic agents. Methods The human neuroblastoma cell lines (JF, SK-N-SH) were transfected with small interfering (si) RNA targeted at GRP. Apoptosis was assessed by DNA fragmentation assay. Immunoblotting was used to confirm molecular markers of apoptosis, and flow cytometry was performed to determine cell cycle arrest after GRP knockdown. Results siGRP resulted in an increase in apoptosis in the absence of chemotherapeutic interventions. A combination of GRP silencing and chemotherapeutic drugs resulted in enhanced apoptosis when compared to either of the treatment alone. GRP silencing led to increased expression of proapoptotic proteins, p53 and p21. Conclusions Silencing of GRP induces apoptosis in neuroblastoma cells; it acts synergistically with chemotherapeutic effects of etoposide and vincristine. GRP knockdown-mediated apoptosis appears to be associated with upregulation of p53 in neuroblastoma cells. Targeting GRP may be postulated as a potential novel agent for combinational treatment to treat aggressive neuroblastomas.

Significance of gastrin-releasing peptide in ovarian cancer ES2 cells

“…This suggested that GRP has a role in the proliferation and cell migration of human ovarian cancer cells. This finding is consistent with that of previous studies concerning other types of tumor (15)(16)(17)(18). Ischia et al (15) reported that GRP and GRPR are overexpressed in prostate cancer and can stimulate the growth of prostate cancer cells.…”

“…Ischia et al (15) reported that GRP and GRPR are overexpressed in prostate cancer and can stimulate the growth of prostate cancer cells. In addition, GRP was found to be associated with the migration and metastasis of cancer cells in neuroblastoma and breast cancer (16)(17)(18). It can therefore be concluded that GRP may be a potential novel target for the treatment of ovarian cancers.…”

Differential regulation of cyclin-dependent kinase inhibitors in neuroblastoma cells

“…We previously reported that GRP activated the PI3K/AKT signaling pathway to promote cell cycle progression in neuroblastoma cells [5], whereas, silencing GRP increased the expression of p21 in SK-N-SH cells [19]. In order to confirm the differential regulations of GRP-R signaling pathway on p21 and p27, we next examined the expressions of p21 and p27 using tetracycline-inducible GRP silencing in BE(2)-C cells.…”

Targeting Gastrin-Releasing Peptide Suppresses Neuroblastoma Progression via Upregulation of PTEN Signaling

“…Using our above mentioned metastasis model, we were able to demonstrate that targeting GRP inhibited tumor metastasis. Lack of complete inhibition of primary tumor growth could be potentially due to a marginal reduction of the proliferative capacity of neuroblastoma cells after GRP silencing [28]. The result of these in vivo experiments illustrates the inhibition of several key features in the invasion-metastasis cascade.…”