Pro-inflammatory gene expression in solid glioblastoma microenvironment and in hypoxic stem cells from human glioblastoma

Abstract

BackgroundAdaptation to hypoxia and consequent pro-inflammatory gene expression of prostate and breast carcinomas have been implicated in the progression toward cancer malignant phenotype. Only partial data are available for the human tumor glioblastoma multiforme (GBM). The aim of our study was to analyze the hypoxic and pro-inflammatory microenvironment in GBMs and to demonstrate that in a stem/progenitor cell line derived from human glioblastoma (GBM-SCs), hypoxia activates a coordinated inflammatory response, evidencing an invasive and migratory phenotype.MethodsFrom each of 10 human solid glioblastomas, clinically and histopathologically characterized, we obtained three surgical samples taken from the center and the periphery of the tumor, and from adjacent host normal tissue. Molecular and morphological analyses were carried out using quantitative real-time PCR and western blot (WB). GBM stem and differentiated cells were incubated under hypoxic conditions and analyzed for pro-inflammatory gene expression and for invasive/migratory behavior.ResultsA panel of selected representative pro-inflammatory genes (RAGE and P2X7R, COX2, NOS2 and, PTX3) were analyzed, comparing tumor, peritumor and host normal tissues. Tumors containing leukocyte infiltrates (as assessed using CD45 immunohistochemistry) were excluded. Selected genes were overexpressed in the central regions of the tumors (i.e. in the more hypoxic areas), less expressed in peripheral regions, and poorly expressed or absent in adjacent normal host tissues. Western blot analysis confirmed that the corresponding pro-inflammatory proteins were also differently expressed. Hypoxic stem cell lines showed a clear time-dependent activation of the entire panel of pro-inflammatory genes as compared to differentiated tumor cells. Biological assays showed that invasive and migratory behavior was strengthened by hypoxia only in GBM stem cells.ConclusionsIn human solid glioblastoma we have observed a coordinated overexpression of a panel of pro-inflammatory genes as compared to host normal tissue. We have also evidenced a similar pattern of overexpressed genes in GBM-SCs after hypoxic treatment, showing also a gain of invasive and migratory function that was lost when these stem cells differentiated. We suggest that, as has been previously described for prostatic and mammary carcinoma, in human glioblastoma acquisition of a proinflammatory phenotype may be relevant for malignant progression.

Pharmacological inhibition of lipid droplet formation enhances the effectiveness of curcumin in glioblastoma

“…The microenvironment of glioblastoma tumors is characterized by the infiltration of hyperactivated immune cells, which aggravate disease progression. Thus, it can be hypothesized that inhibition of lipid metabolism can also reduce inflammation at tumor sites [88][89][90]. However, the potential side effects of pyrrolidine-2 deter its use in vivo.…”

Therapeutic Potential of Glioblastoma Stem Cells

“…Different studies tried to generate a model of GBM and they hypothesized that the GBM tumor mass was a multilayer and the every tumor layer showed distinct characteristic. Pistollato et al [10] describe GSCs distribution according to tissue hypoxic gradient, Piccirilla et al [11] found a different behavior of GSCs derived from distinct tumor areas and Tafani et al [12] demonstrated that the different pro-inflammatory gene expression of diverse tumor areas. The tumor cells are hypoxic, showed high activation of NF-kB and the expression of pro-inflammatory genes were high, the peri-tumor area showed the high activation of NFkB and the pro-inflammatory genes expressions were low, the core region of the tumor was high proliferation capacity and clonogenic ability, the expression of differentiation markers were low and the genetic abnormalities not shared with the tumor periphery.…”

Molecular biology of oncogenic inflammatory processes. I. Non-oncogenic and oncogenic pathogens, intrinsic inflammatory reactions without pathogens, and microRNA/DNA interactions (Review)

“…In response, tumor cells proliferate (ᛏ Ki67) and migrate; and resting stem cells undergo activation and enter the cell cycle. These stem cells are vulnerable to malignant transformation instead of differentiation (156).…”