Entry and exit of chemotherapeutically-promoted cellular dormancy in glioblastoma cells is differentially affected by the chemokines CXCL12, CXCL16, and CX3CL1

Abstract

Glioblastoma multiforme (GBM) is a malignant brain tumor that evades therapy regimens. Since cellular dormancy is one strategy for surviving, and since chemokines determine the environmental conditions in which dormancy occurs, we investigated how chemokines affect temozolomide (TMZ)-promoted cellular dormancy entry and exit in GBM cells. TMZ administration over ten days promoted cellular dormancy entry, whereas discontinuing TMZ for a further 15 days resulted in resumption of proliferation. Co-administration of a chemokine cocktail containing CXCL12, CXCL16, and CX3CL1 resulted in both delayed entry and exit from cellular dormancy. A microarray-based transcriptome analysis in LN229 GBM cells revealed that cellular dormancy entry was characterized by an increased expression of CCL2 and SAA2, while THSD4, FSTL3, and VEGFC were upregulated during dormancy exit. Co-stimulation with the chemokine cocktail reduced upregulation of identified genes. After verifying the appearance of identified genes in human GBM primary cultures and ex vivo samples, we clarified whether each chemokine alone impacts cellular dormancy mechanisms using specific antagonists and selective CRISPR/Cas9 clones. While expression of CCL2 and SAA2 in LN229 cells was altered by the CXCL12-CXCR4-CXCR7 axis, CXCL16 and CX3CL1 contributed to reduced upregulation of THSD4 and, to a weaker extent, of VEGFC. The influence on FSTL3 expression depended on the entire chemokine cocktail. Effects of chemokines on dormancy entry and exit-associated genes were detectable in human GBM primary cells, too, even if in a more complex, cell-specific manner. Thus, chemokines play a significant role in the regulation of TMZ-promoted cellular dormancy in GBMs.

The Role of CXCL16 in the Pathogenesis of Cancer and Other Diseases

“…Along with other chemokines, CXCL16 is involved in the regulation of the cellular dormancy of glioblastoma multiforme cells after exposure to temozolomide (TMZ) [ 191 ], a standard drug used in the treatment of this cancer [ 192 ]. Exposure of glioblastoma multiforme cells to TMZ stops cell division.…”

“…Exposure of glioblastoma multiforme cells to TMZ stops cell division. After discontinuation of the therapy, tumor cell proliferation resumes [ 191 ]. This process is regulated by the chemokine system, in particular CXCL16, and also by CX3C motif chemokine ligand 1 (CX3CL1) and CXC motif chemokine ligand 12 (CXCL12) [ 191 ].…”

Targeting Intercellular Communication in the Bone Microenvironment to Prevent Disseminated Tumor Cell Escape from Dormancy and Bone Metastatic Tumor Growth

“…Another therapeutic strategy to maintain bone marrow microenvironment-induced dormancy of DTC may be to target the CXCL12/CXCR4 axis. In addition to what has been discussed above, it has also been suggested that delivery of CXCL12 to chemotherapy-induced dormant neuroblastoma cells led to down-regulation of genes associated with cell quiescence [ 294 ], and dormant breast tumor cells in lung metastatic sites had reduced CXCR4 expression [ 295 ], reinforcing the role CXCL12/CXCR4 signaling may play in reanimation of dormant tumor cells in metastatic sites.…”

Role of chemokines in hepatocellular carcinoma (Review)

“…In addition, the interaction between CXCR6 and CXCL16 leads to an increase in IL-4 secretion, which activates natural killer (NK) T cells to inhibit the proliferation of malignant cells ( 27 ). A study on gliomas revealed that CXCL16 and CX3CL1 downregulate the expression levels of vascular endothelial growth factor C ( 29 ), suggesting that they may inhibit tumor growth by decreasing angiogenesis. However, Takiguchi et al ( 30 ) found that soluble CXCL16 produced by mesenchymal stem cells (MSCs) via Wnt5a-Ror2 increased proliferation of human gastric cancer MKN45 cells expressing CXCR6.…”

“…In the past, it was considered that CXCR4 was the only receptor of CXCL12. CXCL12/CXCR4 binds specifically and is commonly involved in various pathophysiological processes, such as anti-apoptotic and angiogenesis processes ( 29 ). Additionally, CXCL12/CXCR4 serves a key role in cell migration to multiple organs, including the liver, bone marrow and lungs ( 91 ).…”