Metabolic Reprogramming of Glioblastoma Cells during HCMV Infection Induces Secretome-Mediated Paracrine Effects in the Microenvironment

Abstract

Glioblastoma (GBM) is an aggressive primary central nervous system neoplasia with limited therapeutic options and poor prognosis. Following reports of cytomegalovirus (HCMV) in GBM tumors, the anti-viral drug Valganciclovir was administered and found to significantly increase the longevity of GBM patients. While these findings suggest a role for HCMV in GBM, the relationship between them is not clear and remains controversial. Treatment with anti-viral drugs may prove clinically useful; however, their results do not explain the underlying mechanism between HCMV infection and GBM progression. We hypothesized that HCMV infection would metabolically reprogram GBM cells and that these changes would allow for increased tumor progression. We infected LN-18 GBM cells and employed a Seahorse Bioanalyzer to characterize cellular metabolism. Increased mitochondrial respiration and glycolytic rates were observed following infection. These changes were accompanied by elevated production of reactive oxygen species and lactate. Due to lactate’s numerous tumor-promoting effects, we examined the impact of paracrine signaling of HCMV-infected GBM cells on uninfected stromal cells. Our results indicated that, independent of viral transmission, the secretome of HCMV-infected GBM cells was able to alter the expression of key metabolic proteins and epigenetic markers. This suggests a mechanism of action where reprogramming of GBM cells alters the surrounding tumor microenvironment to be permissive to tumor progression in a manner akin to the Reverse-Warburg Effect. Overall, this suggests a potential oncomodulatory role for HCMV in the context of GBM.

Intermittent Cytomegalovirus Infection Alters Neurobiological Metabolism and Induces Cognitive Deficits in Mice

“…Systemic inflammation could exert effects on the BBB by affecting the BMECs. Our metabolic profiling of BMECs indicated a significant initial increase in GLUT1 expression in MCMV infected animals which is consistent with previous findings where CMV has been reported to upregulate glycolysis pathways during infection (Combs et al, 2020; Harrison et al, 2022; Munger et al, 2006; Yu et al, 2011). Similar upregulation of glycolysis pathways has been reported in AD brains (Mooradian et al, 1997).…”

“…In addition to the glycolytic changes discussed above, mitochondrial function is significantly altered in MCMV infected BMECs in aged mice, 12 MPI. Our group previously published that CMV infection induces mitochondrial dysfunction in fibroblasts and glioblastoma cell lines (Combs et al, 2020; Harrison et al, 2022). Our current and previous findings are consistent with literature associating metabolism and mitochondrial dysfunction with dementia (Gao et al, 2020; Wilkins and Swerdlow, 2021).…”

“…Ultimately, a lack of mechanisms linking pathogens and the origins of dementia impede progress. Intriguingly, CMV pathogenesis mirrors many of the features of AD pathology including calcium dysregulation (Sharon-Friling et al, 2006), amyloid deposition (Lurain et al, 2013), iron dysfunction (Crowe et al, 2004), autophagic (Taisne et al, 2019, and mitochondrial dysfunction (Betsinger et al, 2021;Combs et al, 2020;Harrison et al, 2022).…”

“…The ability of CMV to alter the metabolic profile of host cells to produce the biomaterials and energy needed for viral replication is well described (Combs et al, 2020; Harrison et al, 2022; Saffran et al, 2007; Spaggiari et al, 2008; Suliman et al, 2004; Vastag et al, 2011). This metabolic reprogramming often results in impaired bioenergetics and subsequent increases in reactive oxygen species (ROS) production.…”

Hallmarks of Metabolic Reprogramming and Their Role in Viral Pathogenesis

“…Increased glycolysis also correlates with an increase in glucose consumption and lactate production. This was confirmed using primary human foreskin fibroblast (HFF) cells and non-tumorigenic breast epithelial cells infected with the human cytomegalovirus (HCMV) or adenovirus, respectively [ 121 , 122 , 123 , 124 ]. A decrease in oxygen consumption used in mitochondrial OXPHOS was demonstrated in adenovirus-infected non-tumorigenic breast epithelial cells [ 124 ].…”