Julie K. Schwarz

Glutaminase Inhibitors Induce Thiol-Mediated Oxidative Stress and Radiosensitization in Treatment-Resistant Cervical Cancers

Abstract The purpose of this study was to determine if radiation (RT)-resistant cervical cancers are dependent upon glutamine metabolism driven by activation of the PI3K pathway and test whether PI3K pathway mutation predicts radiosensitization by inhibition of glutamine metabolism. Cervical cancer cell lines with and without PI3K pathway mutations, including SiHa and SiHa PTEN−/− cells engineered by CRISPR/Cas9, were used for mechanistic studies performed in vitro in the presence and absence of glutamine starvation and the glutaminase inhibitor, telaglenastat (CB-839). These studies included cell survival, proliferation, quantification of oxidative stress parameters, metabolic tracing with stable isotope-labeled substrates, metabolic rescue, and combination studies with L-buthionine sulfoximine (BSO), auranofin (AUR), and RT. In vivo studies of telaglenastat ± RT were performed using CaSki and SiHa xenografts grown in immune-compromised mice. PI3K-activated cervical cancer cells were selectively sensitive to glutamine deprivation through a mechanism that included thiol-mediated oxidative stress. Telaglenastat treatment decreased total glutathione pools, increased the percent glutathione disulfide, and caused clonogenic cell killing that was reversed by treatment with the thiol antioxidant, N-acetylcysteine. Telaglenastat also sensitized cells to killing by glutathione depletion with BSO, thioredoxin reductase inhibition with AUR, and RT. Glutamine-dependent PI3K-activated cervical cancer xenografts were sensitive to telaglenastat monotherapy, and telaglenastat selectively radiosensitized cervical cancer cells in vitro and in vivo. These novel preclinical data support the utility of telaglenastat for glutamine-dependent radioresistant cervical cancers and demonstrate that PI3K pathway mutations may be used as a predictive biomarker for telaglenastat sensitivity.

Standardized Uptake Value for 18F-Fluorodeoxyglucose Is a Marker of Inflammatory State and Immune Infiltrate in Cervical Cancer

Abstract Purpose: Chemoradiotherapy for locally advanced cervical cancer fails in over a third of patients. Biomarkers with therapeutic implications are therefore needed. We investigated the relationship between an established prognostic marker, maximum standardized uptake value (SUVmax) on 18F-fluorodeoxyglucose positron emission tomography, and the inflammatory and immune state of cervical cancers. Experimental Design: An SUVmax most prognostic for freedom from progression (FFP) was identified and compared with known prognostic clinical variables in a cohort of 318 patients treated with definitive radiation with prospectively collected clinical data. Gene set enrichment analysis (GSEA) and CIBERSORT of whole-transcriptome data from 68 patients were used to identify biological pathways and immune cell subpopulations associated with high SUVmax. IHC using a tissue microarray (TMA, N = 82) was used to validate the CIBERSORT findings. The impact of macrophages on cervical cancer glucose metabolism was investigated in coculture experiments. Results: SUVmax <11.4 was most prognostic for FFP (P = 0.001). The GSEA showed that high SUVmax is associated with increased gene expression of inflammatory pathways, including JAK/STAT3 signaling. CIBERSORT and CD68 staining of the TMA showed high SUVmax tumors are characterized by a monocyte-predominant immune infiltrate. Coculture of cervical cancer cells with macrophages or macrophage-conditioned media altered glucose uptake, and IL6 and JAK/STAT3 signaling contribute to this effect. Conclusions: SUVmax is a prognostic marker in cervical cancer that is associated with activation of inflammatory pathways and tumor infiltration of myeloid-derived immune cells, particularly macrophages. Macrophages contribute to changes in cervical cancer glucose metabolism. See related commentary by Williamson et al., p. 4136

Improving cervical cancer survival–A multifaceted strategy to sustain progress for this global problem

AbstractCervical cancer is associated with profound socioeconomic and racial disparities in incidence, mortality, morbidity, and years of life lost. The last standard‐of‐care treatment innovation for locally advanced cervical cancer occurred in 1999, when cisplatin chemotherapy was added to pelvic radiation therapy (chemoradiation therapy). Chemoradiation therapy is associated with a 30%–50% failure rate, and there is currently no cure for recurrent or metastatic disease. The enormity of the worldwide clinical problem of cervical cancer morbidity and mortality as well as the egregiously unchanged mortality rate over the last several decades are recognized by the National Institutes of Health as urgent priorities. This is reflected within the Office of Research on Women's Health effort to advance National Institutes of Health research on the health of women, as highlighted in a recent symposium. In the current review, the authors address the state of the science and opportunities to improve cervical cancer survival with an emphasis on improving access, using technology in innovative and widely implementable ways, and improving current understanding of cervical cancer biology.Lay summary Cervical cancer is associated with profound socioeconomic and racial disparities in incidence, mortality, morbidity, and years of life lost. In this review, the state of the science and opportunities to improve cervical cancer survival are presented with an emphasis on improving access, using technology in innovative and widely implementable ways, and improving current understanding of cervical cancer biology.

Monounsaturated and Diunsaturated Fatty Acids Sensitize Cervical Cancer to Radiation Therapy

Abstract Obesity induces numerous physiological changes that can impact cancer risk and patient response to therapy. Obese patients with cervical cancer have been reported to have superior outcomes following chemoradiotherapy, suggesting that free fatty acids (FFA) might enhance response to radiotherapy. Here, using preclinical models, we show that monounsaturated and diunsaturated FFAs (uFFA) radiosensitize cervical cancer through a novel p53-dependent mechanism. UFFAs signaled through PPARγ and p53 to promote lipid uptake, storage, and metabolism after radiotherapy. Stable isotope labeling confirmed that cervical cancer cells increase both catabolic and anabolic oleate metabolism in response to radiotherapy, with associated increases in dependence on mitochondrial fatty acid oxidation for survival. In vivo, supplementation with exogenous oleate suppressed tumor growth in xenografts after radiotherapy, an effect that could be partially mimicked in tumors from high fat diet–induced obese mice. These results suggest that supplementation with uFFAs may improve tumor responses to radiotherapy, particularly in p53 wild-type tumors. Significance: Metabolism of monounsaturated and diunsaturated fatty acids improves the efficacy of radiotherapy in cancer through modulation of p53 activity. See related commentary by Jungles and Green, p. 4513

Characterization of the vaginal microbiome of postmenopausal patients receiving chemoradiation for locally advanced cervical cancer

The standard-of-care treatment of locally advanced cervical cancer includes pelvic radiation therapy with concurrent cisplatin-based chemotherapy and is associated with a 30%-50% failure rate. New prognostic and therapeutic targets are needed to improve clinical outcomes. The vaginal microbiome has been linked to the pathogenesis of cervical cancer, but little is known about the vaginal microbiome in locally advanced cervical cancer as it relates to chemoradiation. In this pilot study, we utilized 16S rRNA gene community profiling to characterize the vaginal microbiomes of 26 postmenopausal women with locally advanced cervical cancer receiving chemoradiation. Our analysis revealed diverse anaerobe-dominated communities whose taxonomic composition, diversity, or bacterial abundance did not change with treatment. We hypothesized that characteristics of the microbiome might correlate with treatment response. Pretreatment microbial diversity and bacterial abundance were not associated with disease recurrence. We observed a greater relative abundance of Fusobacterium in patients who later had cancer recurrence, suggesting that Fusobacterium could play a role in modifying treatment response. Taken together, this hypothesis-generating pilot study provides insight into the composition and dynamics of the vaginal microbiome, offering proof of concept for the future study of the microbiome and its relationship with treatment outcomes in locally advanced cervical cancer.

Chemoradiation Reprograms Tumor Cells and the Immune Microenvironment in Cervical Cancer

Abstract Despite advances in screening and prevention, cervical cancer remains a leading cause of cancer-related deaths worldwide, underscoring the need for better treatments. In this study, we conducted a multicohort longitudinal study of human cervical tumors and the tumor microenvironment during chemoradiotherapy (CRT) and integrated RNA sequencing and single-cell transcriptomics to define the cellular and molecular programs shaping cell interactions and how CRT alters them. The analysis identified multiple therapeutic targets in CRT-resistant tumors, notably including MDM2, a key mediator of radiation responses in tumor and immune cells. MDM2 inhibition enhanced the effects of radiotherapy in human papillomavirus (HPV)–positive, TP53 wild-type cervical cancer cells; improved radiation response; and reshaped the immune landscape in preclinical models. These findings highlight the potential of combining MDM2 inhibition with CRT to overcome resistance and improve patient outcomes. The insights into therapy-induced changes in tumor and immune compartments could guide improved strategies against treatment-resistant HPV-positive cancers. Significance: Mapping of the impact of chemoradiation on cellular interactions in cervical cancer reveals how treatment reshapes the tumor microenvironment and highlights targets for developing future immunotherapeutic approaches. See related commentary by Klopp, p. 1540