Combination of a Toll-like receptor 9 agonist with everolimus interferes with the growth and angiogenic activity of renal cell carcinoma

Loss of endothelial programmed cell death 10 activates glioblastoma cells and promotes tumor growth

BACKGROUND

Neo-angiogenesis is a hallmark of glioblastoma (GBM) and is sustained by autocrine and paracrine interactions between neoplastic and nonneoplastic cells. Programmed cell death 10 (PDCD10) is ubiquitously expressed in nearly all tissues and plays crucial roles in regulating angiogenesis and apoptosis. We recently discovered the absence of PDCD10 expression in the tumor vessels of GBM patients. This raised the hypothesis that loss of endothelial PDCD10 affected GBM cell phenotyping and tumor progression.

METHODS

Endothelial PDCD10 was silenced by siRNA and lentiviral shRNA. The tumor cell phenotype was studied in direct and indirect co-culture of endothelial cells (ECs) with U87 or LN229. Angiogenic protein array was performed in the media of PDCD10-silenced ECs. Tumor angiogenesis and tumor growth were investigated in a human GBM xenograft mouse model.

RESULTS

Endothelial silence of PDCD10 significantly stimulated tumor cell proliferation, migration, adhesion, and invasion and inhibited apoptosis in co-cultures. Stable knockdown of endothelial PDCD10 increased microvessel density and the formation of a functional vascular network, leading to a 4-fold larger tumor mass in mice. Intriguingly, endothelial deletion of PDCD10 increased (≥2-fold) the release of 20 of 55 tested proangiogenic factors including VEGF, which in turn activated Erk1/2 and Akt in GBM cells.

CONCLUSIONS

For the first time, we provide evidence that loss of endothelial PDCD10 activates GBM cells and promotes tumor growth, most likely via a paracrine mechanism. PDCD10 shows a tumor-suppressor-like function in the cross talk between ECs and tumor cells and is potentially implicated in GBM progression.

CpG-oligodeoxynucleotides suppress the proliferation of A549 lung adenocarcinoma cells via toll-like receptor 9 signaling and upregulation of Runt-related transcription factor 3 expression

The aim of the present study was to investigate the effect of CpG-oligodeoxynucelotides (CpG-ODN) on the proliferation of the A549 human lung adenocarcinoma cell line and the expression of Runt-related transcription factor 3 (Runx3) and investigate the association between the toll-like receptor 9 (TLR9) signaling pathway and Runx3 expression during A549 cell proliferation. Different concentrations of CpG-ODN were used in this study to stimulate A549 cells and the expression of Runx3 at the mRNA or protein level was detected by reverse transcription-polymerase chain reaction or western blot analysis. Moreover, Runx3 siRNA was synthesized and transiently transfected into the A549 cells and the MTT assay was used to detect the effects of CpG-ODN on transfected cell growth. Our data demonstrated that CpG-ODN significantly inhibited the proliferation of A549 cells. The expression of Runx3 in the mRNA and protein level was increased in A549 cells stimulated by CpG-ODN. The CpG-ODN-stimulated cell proliferation was significantly inhibited in Runx3 siRNA-transfected A549 cells. In conclusion, CpG-ODN may bind to TLR9, inhibit the proliferation of A549 cells and upregulate the expression of Runx3.