Radioresistant Cancer Research Articles

The role of lipid metabolism in cancer radioresistance.

Radiotherapy is one of the main therapies for cancer. The process leading to radioresistance is still not fully understood. Cancer radiosensitivity is related to the DNA reparation of cancer cells and the tumor microenvironment (TME), which supports cancer cell survival. Factors that affect DNA reparation and the TME can directly or indirectly affect the radiosensitivity of cancer. Recent studies have shown that lipid metabolism in cancer cells, which is involved in the stability of cell membrane structure, energy supply and signal transduction of cancer cells, can also affect the phenotype and function of immune cells and stromal cells in the TME. In this review, we discussed the effects of lipid metabolism on the radiobiological characteristics of cancer cells and the TME. We also summarized recent advances in targeted lipid metabolism as a radiosensitizer and discussed how these scientific findings could be translated into clinical practice to improve the radiosensitivity of cancer.

Effects of irradiation with different fractionations on radioresistant esophageal cancer cells and lung tissues

BackgroundLocal recurrence is the main cause of treatment failure for esophageal cancer and a large part of them require re-irradiation which needs to face the two major challenges of radioresistance and radiation-induced lung injury (RILI). This study aimed to evaluate the effects of irradiation with different fractionations on inhibition in radioresistant esophageal cancer cells in vitro and RILI in vivo. MethodsEC109R was selected from the human esophageal squamous carcinoma cell line EC109 by multiple exposures and verified to be radioresistant through colony forming assay and cell proliferation assay. EC109R was irradiated with different fractionations (conventional radiotherapy, CR: 2 Gy/d, 5 d; pulsed low dose-rate radiotherapy, PLDR: 0.2 Gy x 10 pulses with 3-min intervals/d, 5 d; hypo-fractionated radiotherapy, HR: 5 Gy/d, 2 d) to verify their inhibition by CCK-8. The protection of PLDR on RILI was assessed by H&E-staining paraffin sections and mice serum TGF-β1 levels. ResultsEC109R exhibited much better radioresistance (p < 0.0001) than EC109 in colony forming and cell proliferation assays. For EC109R, PLDR showed slightly lower inhibition by detection of optical density than HR (p = 0.0025) but similar to CR (p = 0.1155). In addition, pathological sections of lung tissues from PLDR group showed less alveolar structural damage and inflammatory cells infiltration, and serum TGF-β1 levels were significantly lower than those in the other two fractionations (vs CR: p = 0.0092; vs HR: p = 0.0045). ConclusionPLDR could effectively inhibit the proliferation of radioresistant esophageal cancer cells in vitro and mitigate RILI in vivo.

C-Jun-mediated JMJD6 restoration enhances resistance of liver cancer to radiotherapy through the IL-4-activated ERK pathway.

Radiotherapy is widely used in the treatment of liver cancer, but the efficacy can be limited by radioresistance. In this study, we attempt to delineate the possible molecular mechanism of c-Jun-regulated Jumonji domain-containing protein 6/interleukin 4/extracellular signal-regulated kinase(JMJD6/IL-4/ERK) axis in radioresistance of liver cancer. The expression of c-Jun was quantified in liver cancer tissues and cell lines, and the results indicated that c-Jun was upregulated in liver cancer tissues and cells. We further illustrated the role of c-Jun following gain- and loss-of-function strategies in malignant phenotypes of liver cancer cells. It was established that c-Jun elevated JMJD6 expression and augmented the malignancy and aggressiveness of liver cancer cells. The in vivo effects of c-Jun on radioresistance in liver cancer were validated in nude mice, in response to IL-4 knockdown or the ERK pathway inhibitor, PD98059. In the presence of JMJD6 upregulation, the expression of IL-4 was elevated in mice with liver cancer, which enhanced the radiation resistance. Moreover, knockdown of IL-4 inactivated the ERK pathway, thereby reversing the radiation resistance caused by overexpressed JMJD6 in tumor-bearing mice. Taken together, c-Jun augments the radiation resistance in liver cancer by activating the ERK pathway through JMJD6-upregulated IL-4 transcription.

Role of ionizing radiation activated NRF2 in lung cancer radioresistance

Radiotherapies are commonly used to target remaining tumor niches after surgery of solid tumors but are restricted due to therapeutic resistance. Several pathways of radioresistance have been reported in various cancers. This study investigates the pivotal role of Nuclear factor-erythroid 2–related factor 2 (NRF2) in the activation of DNA damage repair in lung cancer cells after x-rays exposure. To explore the NRF2 activation after ionizing irradiations, this study uses a knockdown of NRF2, which shows potential DNA damage after x-rays irradiation in lung cancers. This work further shows that NRF2 knockdown disrupts damaged DNA repair by inhibiting DNA-dependent protein kinase catalytic subunit. At the same time, NRF2 knockdown by shRNA considerably disparate homologous recombination by interfering with Rad51 expression. Further investigation of the associated pathway reveals that NRF2 activation mediates DNA damage response via the mitogen-activated protein kinase (MAPK) pathway as the knockout of NRF2 directly enhances intracellular MAPK phosphorylation. Similarly, both N-acetylcysteineand constitutive knockout of NRF2 disrupt DNA-dependent protein kinase catalytic subunit, while NRF2 knockout failed to upregulate Rad51 expression after irradiation in-vivo. Taken together, these findings advocate NRF2 plays a critical role in the development of radioresistance by upregulating DNA damage response via the MAPK pathway, which can be of great significance.

Energy Metabolism Is Altered in Radioresistant Rectal Cancer.

Resistance to neoadjuvant chemoradiation therapy is a significant clinical challenge in the management of rectal cancer. There is an unmet need to identify the underlying mechanisms of treatment resistance to enable the development of biomarkers predictive of response and novel treatment strategies to improve therapeutic response. In this study, an in vitro model of inherently radioresistant rectal cancer was identified and characterized to identify mechanisms underlying radioresistance in rectal cancer. Transcriptomic and functional analysis demonstrated significant alterations in multiple molecular pathways, including the cell cycle, DNA repair efficiency and upregulation of oxidative phosphorylation-related genes in radioresistant SW837 rectal cancer cells. Real-time metabolic profiling demonstrated decreased reliance on glycolysis and enhanced mitochondrial spare respiratory capacity in radioresistant SW837 cells when compared to radiosensitive HCT116 cells. Metabolomic profiling of pre-treatment serum samples from rectal cancer patients (n = 52) identified 16 metabolites significantly associated with subsequent pathological response to neoadjuvant chemoradiation therapy. Thirteen of these metabolites were also significantly associated with overall survival. This study demonstrates, for the first time, a role for metabolic reprograming in the radioresistance of rectal cancer in vitro and highlights a potential role for altered metabolites as novel circulating predictive markers of treatment response in rectal cancer patients.

High expression of cytoplasmic FOXO3 protein associated with poor prognosis of rectal cancer patients: A study from Swedish clinical trial of preoperative radiotherapy to big database analysis

IntroductionAccumulating evidence has implicated a pivotal role for FOXO3, FOXM1 and SIRT6 in cancer progression. The majority of researches focused on the functions of these proteins in drug resistance, but their relationships with radiotherapy (RT) response remain unclear. In this study, we examined protein expression of FOXO3, FOXM1 and SIRT6 and their clinical significance in a Swedish rectal cancer trial of preoperative RT. MethodsExpression of FOXO3, FOXM1 and SIRT6 protein was examined by immunohistochemistry in patient samples. Genetic analysis of FOXO3, FOXM1 and SIRT6 were performed by cBioportal and MEXPRESS database. Gene-gene network analysis was conducted using GeneMANIA. Functional enrichment analysis was performed based on LinkedOmics and Metascape online software. ResultsFOXO3 and FOXM1were mainly expressed in the cytoplasm in both normal and tumour tissues, and SIRT6 in both the cytoplasm and nucleus in normal and tumour tissues. FOXO3 and FOXM1 expression increased from normal mucosa to primary cancer (P < 0.001), while SIRT6 expression decreased from normal mucosa to primary cancer (P < 0.001). High FOXO3 expression correlated with late TNM stage (P = 0.040), distant metastasis (P = 0.032) and independently with disease free survival (DFS) in the RT patients (HR = 7.948; P = 0.049; 95% CI = 1.002–63.032) but not in non-RT patients (P > 0.05). Genetic analysis indicated that DNA methylation status contributed to FOXO3 overexpression. Functional enrichment analysis demonstrated that FOXO3 was closely related to metabolism-related signalling pathway which in turn associated with cancer radioresistance. Moreover, there were strong gene–gene interactions between FOXO3 and metabolism-related signalling. ConclusionsOur findings suggest that FOXO3 may be a prognostic factor in rectal cancer patients with RT.

Abstract 2813: Pyruvate kinase M2 confers radioresistance in head and neck cancer through reprograming the tumor-immune microenvironment via ECM1

Abstract Radiotherapy plays an essential role in cancer treatment, yet radioresistance remains a major barrier to therapeutic efficacy. A better understanding of the predominant pathways determining radiotherapy response could help develop mechanism-informed therapies to improve cancer management. PKM2, an enzyme that regulates the final rate-limiting step of glycolysis, has different functions in the occurrence, progression and metastasis of cancer. However, whether PKM2 plays a vital role in radioresistance is unclear, especially in head and neck squamous cell carcinoma (HNSCC). Here we report the upregulation of PKM2 in primary post-radiotherapy tumor tissues collected from radioresistant HNSCC patients. Using multidisciplinary approaches, we found elevated PKM2 in response to radiation, which confers radioresistance in HNSCC cells via extracellular matrix protein 1 (ECM1). Mechanistically, PKM2 activates STAT5 signaling pathway in HNSCC cells upon radiation, which enhances ECM1 expression. Moreover, ECM1 upregulation mediated by PKM2 prevents effector T cells from migrating to radioresistant head and neck tumors. While depletion of ECM1 overcomes PKM2-mediated radioresistance in orthotopic xenograft mice through altering the profile of chemo-attractants, which in turn remodels the tumor microenvironment to promote more cytotoxic T cells home to tumors. These novel and significant findings not only demonstrate a novel mechanism underpinning the interaction between tumor-derived PKM2 and immune cells in radioresistance but also provide a possible therapeutic strategy to overcome the failure of radiotherapy in HNSCC patients. Citation Format: Fanghui Chen, Yang Fan, Chris Tang, Qin Richard, Zheng Wei, Yong Teng. Pyruvate kinase M2 confers radioresistance in head and neck cancer through reprograming the tumor-immune microenvironment via ECM1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2813.

Abstract 3501: A genome-wide screen for determinants of radioresistance in head and neck cancer

Abstract Introduction: Head and neck cancer (HNC) is the seventh most common cancer worldwide with over 1 million new cases diagnosed each year. Radioresistance is a major cause of both treatment failure and poor prognosis, with locoregional recurrence after radiotherapy occurring in up to 50% of HNC patients. Despite the discovery of individual genes implicated in the ability of HNC cells to develop radioresistance, a systematic evaluation remains to be undertaken. This project is the first to conduct genome-wide CRISPR screens for regulators of radioresistance in HNC, with the aim to identify phenotype-driving genes and pathways. Experimental Procedures: Genome-wide negative selection screens were conducted on HNC cell lines using the Toronto KnockOut (TKO) CRISPR library. Monoclonal Cas9 cell lines were derived from UT-SCC-42A (42A), FaDu, and PE/CA-PJ41 (clone D2) with Cas9 editing efficiencies &amp;gt;80%. Library-transduced cells were treated with the minimum dose of radiation resulting in cessation of cell growth (10 Gy for 42A and FaDu; 8 Gy for PE/CA-PJ41). Genomic DNA from the resultant radioresistant populations was extracted and sequenced on the Illumina NextSeq 500. MAGeCK analysis of read counts identified gene targets of significantly depleted gRNAs after irradiation. Genes that correlated with overall survival (OS) in the TCGA Pan-Cancer database were selected for further investigation. The top candidate genes in the determination of radioresponse were validated using cell proliferation and clonogenic assays. Effects of loss-of-function on cell migration were assessed using scratch wound and transwell migration assays. Results: 117 putative radioresistance genes were identified in the 42A cell line screen; the top ranked hits were MMP14, CD44, CALR, and HHLA1. RNA expression levels of these genes had a significant correlation with OS of radiation-treated HNC patients in the TCGA Pan-Cancer Atlas. Loss-of-function of the candidate genes was confirmed to increase radiosensitivity through live cell imaging in 42A and PJ41 cells, which were further corroborated with clonogenic assays. Downregulation of at least one gene impaired the migration of 42A and PJ41 cells, suggesting a role in cellular invasion and migration. Conclusion: This study will contribute to a deeper understanding of mechanisms of radioresistance in HNC, which continues to be a leading cause of mortality in HNC patients. Future pathway elucidation through transcriptome analysis and functional characterization may reveal additional therapeutic targets that can improve the outcome for HNC patients treated with radiation. Citation Format: Jacqueline H. Law, Pierre-Antoine Bissey, Isabella Kojundzic, Kenneth W. Yip, Fei-Fei Liu. A genome-wide screen for determinants of radioresistance in head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3501.

Abstract 5039: Development of a prostate cancer PDX model radioresistant to PSMA targeted radionuclide therapy

Abstract Prostate cancer is the second most common cancer diagnosis worldwide and the fifth leading cause of cancer related death among men. Lutetium Lu 177 vivivotide tetraxetetan was recently approved by the FDA for treatment of prostate-specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer. However, not all patients respond to treatment and combination therapies may improve outcomes. One approach is to combine targeted radionuclide therapy with inhibitors targeting DNA damage response pathways such as ATM/ATR inhibitors to enhance the radiosensitivity of the cancer cells. Currently, models used to study radioresistance in prostate cancer are based on cancer cell lines or cell-line derived xenograft models, but these models do not account for the heterogenous and complex biology of the disease. To overcome this issue, we aimed at developing a radioresistant PSMA positive prostate cancer patient-derived xenograft (PDX) model based on the ST1273 model (XenoSTART). ST1273 originates from a sixty-five-year-old Hispanic male that did not receive treatment prior to sampling. The model is characterized by overexpression of androgen receptor and PSMA. Tumors were implanted in nude mice and radioresistance was induced by external beam radiation therapy (3 × 2Gy per cycle) until tumor growth was unresponsive to the treatment. Flow cytometry were applied to evaluate if altered proliferation rate or changes in the tumor microenvironment (TME) convers the resistance. Out of five initially treated tumors, one tumor re-occurred after 19 days. Repeating the treatment led to an initial decrease in tumor volume but the growth delay was reduced to 12 days. A third treatment rendered the tumor resistant as tumor growth was unaffected. Current evidence confirms that radioresistance was maintained when passaging, and PSMA expression was unaffected. Next, we tested whether the tumor would also withstand targeted radionuclide therapy. Animals implanted with parental or radioresistant ST1273 tumors were treated with Lu177-PSMA-617 (5MBq, QW x2). The treatment reduced tumor size in both tumor types, but significantly less in the resistant model. Moreover, parental tumors had a significantly slower recurrence of 45 days compared to the resistant tumors that relapsed 24 days after the first dosing. Flow cytometry analysis of control and treated tumors (parental and radioresistant) showed that the radioresistance might be attributed to alterations in the cell cycle control. Altogether, we developed a PDX prostate cancer model that is resistance to external beam radiation and PSMA targeted radionuclide therapy. This model will allow us to further characterize radioresistance and evaluate combinatorial therapy in a clinically relevant model. Citation Format: Maria Thaysen, Esben Christensen, Rikke N. Nielsen, Michael Wick, Mette M. Wessel, Lotte K. Kristensen, Sebastian Gnosa, Carsten H. Nielsen. Development of a prostate cancer PDX model radioresistant to PSMA targeted radionuclide therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5039.

Abstract 2401: Molecular mechanisms of intrinsic radioresistance in breast cancer

Abstract Background: Clinical management of BC includes radiation therapy (RT), with most women receiving RT as part of their treatment. Although effective, many women develop locoregional recurrence, including a disproportionate number of women with triple-negative or inflammatory BC. Unfortunately, the molecular mechanisms that underly RT response and intrinsic radioresistance are poorly understood. We hypothesized that transcriptomic and proteomic changes that occur after ionizing radiation in intrinsically radiosensitive and resistant BC models would offer mechanistic insight into mediators of this differential response. Methods: Intrinsic radiosensitivity across all 10 cell lines was measured with clonogenic survival assays as the surviving fraction (SF) after 2 Gy RT. Gene expression changes were assessed by RNA-Seq 24 hours after 4 Gy RT. For long-course RT, cell lines were treated with fractionated RT (2 Gy x 5 fractions). For in vivo mouse xenograft experiments mice received fractionated RT (2 Gy x 6 fractions). Differential gene expression analysis with DeSeq2 was performed on all samples, followed by pathway analysis with Advaita Bioinformatics’ iPathwayGuide. Protein was collected 1, 12, and 24 hours after RT for RPPA analysis evaluating expression changes in 100 proteins and phospho-proteins with SuperCurve. Results: Clonogenic survival identified a wide range of radiation sensitivity in human BC cell lines (SF 83% - 19%) with no significant correlation (r %lt 0.3) to intrinsic BC subtype. The most highly affected pathways in both resistant and sensitive cell lines 24 hours after RT include cell cycle, cellular senescence, and estrogen signaling pathways. For the long-course RT samples, several pathways were significantly altered in fractionated samples only, including MAPK and Hippo signaling and EGFR tyrosine kinase inhibitor resistance. From the in vivo experiments, pathways uniquely affected in the in vivo samples include IL-17 signaling and transcriptional misregulation in cancer. From the proteomic data, we found that proteins including p53, Bcl-2 family proteins, and cell cycle proteins exhibit expression changes after 1 hour. A significant number of pathways (N=69, p %lt 0.01, FDR 0.05) were affected in radioresistant BC models compared to radiosensitive cell lines and these pathways may underlie intrinsic radioresistance. Conclusions: Ionizing radiation induces transcriptomic and proteomic expression changes that differ between intrinsically sensitive and resistant BC models in both single fraction and fractionated studies. Pathways identified in these analyses offer potential insight into the mechanisms underlying intrinsic radioresistance and suggest biologic vulnerabilities that may be targeted to more effectively treat women at a high risk of local BC recurrence. Genome wide CRIPSR-Cas9 screens are currently underway in these breast cancer models to confirm these vulnerability targets. Citation Format: Breanna N. McBean, Anna R. Michmerhuizen, Kari Wilder-Romans, Benjamin C. Chandler, Lynn M. Lerner, Connor Ward, Meilan Liu, Alan P. Boyle, Corey W. Speers. Molecular mechanisms of intrinsic radioresistance in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2401.

Abstract 2858: Radiotherapy and NK cell-based immunotherapy: An evolutionary double-bind

Abstract Evolution-informed therapies exploit the ecological and evolutionary consequences of drug resistance to inhibit the expansion of treatment resistant populations and prolong time to progression. One strategy, termed an evolutionary double-bind, uses an initial therapy to elicit a specific adaptive mechanism that is then selectively targeted by a follow-on therapy. Here we examine combining radiation therapy followed by immunotherapy as a double bind strategy. Radiotherapy (RT) induces lethal double-strand DNA breaks in tumor cells and radiosensitivity is governed by the cells’ DNA repair capabilities. Radioresistant cancer cells upregulate DNA damage response pathways. However, successful adaptations to RT and other DNA damaging agents can increase natural killer (NK) cell ligand expression on tumor cells increasing their vulnerability to the immune system. We conducted a multidisciplinary investigation of this potential evolutionary double bind using an isogenic cell line model of radiation resistance derived from an androgen-independent human prostate carcinoma cell line (22Rv1). We demonstrate that RT-resistant cells maintain higher expression of NK cell ligands and have a 2-fold increase in sensitivity to NK cell mediated killing. Furthermore, we show that preferential targeting of the RT-resistant population by NK cells is preserved in competition assays with varying initial population frequencies. Scope of treatment responses are dependent on population frequencies in our in vitro analysis. Mathematical modeling quantified three key elements of a double-bind: cost of resistance, inter-specific competition between RT-sensitive and RT-resistant lines, and preferential targeting of RT-resistant lines by NK cells. We conclude that RT followed by immunotherapy produces an evolutionary double bind that can be exploited in heterogenous tumors to limit RT resistance. Furthermore, model simulations predict that extinction of both populations is achievable by sequential RT and NK cell therapy. Citation Format: Kimberly Luddy, Jeffery West, Mark Robertson-Tessi, Bina Desai, Taylor M. Bursell, Sarah Barrett, Joel Brown, Jacintha O'Sullivan, Robert Gatenby, Laure Marignol, Alexander R. Anderson, Cliona O'Farrelly. Radiotherapy and NK cell-based immunotherapy: An evolutionary double-bind [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2858.

Abstract 2411: The pentose-phosphate pathway induces pancreatic cancer radioresistance, a preclinical study with clinical validation

Abstract Purpose: Pancreatic ductal adenocarcinoma (PDAC) is remarkably resistant to standard modalities, including radiotherapy (RT). The mechanisms of radiation resistance in general, and pancreatic cancer in particular, are poorly understood. We hypothesized that metabolic reprogramming may underlie this radioresistance, and moreover, that it would be possible to exploit these changes in metabolism for therapeutic intent. Experimental Design: We established multiple isogenic models of radioresistant PDAC cells. Metabolic profile was investigated using Nanostring technology, labeled-glucose tracing by liquid chromatography-mass spectrometry, Seahorse analysis and exposure to metabolic inhibitors. Patient-derived xenografts (PDXs) were established from patients treated with radiation and RNA sequencing performed. The PDXs were grouped according to clinical RECIST response to radiation (responsive/stable disease vs disease progression) and differential gene expression analysis was performed. Results: The radioresistant cells overexpressed pyruvate dehydrogenase kinase (PDK) and were radiosensitized by the PDK inhibitor dichloroacetate. In keeping with PDK overexpression, radioresistant cells displayed increased glycolysis and downregulated both the tricarboxylic acid cycle and oxidative phosphorylation. Metabolic flux through the pentose-phosphate pathway (PPP) was increased, as were levels of reduced glutathione; PPP inhibition dramatically potentiated radiation-induced cell death. Critically, the PPP was upregulated in PDXs derived from patients who demonstrated clinical resistance to radiotherapy. High transcription levels of 6PGD, the rate-limiting enzyme of the PPP, were associated with a poor radiological response to radiation therapy (p=0.0004) and a lower overall survival (p=0.004). Conclusions: We demonstrate that radioresistant PDAC cells divert the glycolytic flux from the tricarboxylic acid cycle and oxidative phosphorylation to the PPP, thereby increasing their antioxidant capacity and promoting nucleotide synthesis for DNA repair. Furthermore, we show that PDAC cells can be radiosensitized via PPP inhibition. Exploitation of metabolic vulnerabilities to radiosensitize tumors constitutes a novel approach to pancreatic cancer with a real potential to improve clinical outcomes. Citation Format: Ariel Shimoni-Sebag, Ifat Abramovich, Bella Agranovich, Yaarit Sirovsky, Chani Stossel, Dikla Atias, Maria Raitses-Gurevich, Yulia Glick-Gorman, Ofer Margalit, David Regev, Rotem Tal, Itay Tirosh, Talia Golan, Keren Yizhak, Eyal Gottlieb, Yaacov R. Lawrence. The pentose-phosphate pathway induces pancreatic cancer radioresistance, a preclinical study with clinical validation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2411.

Circular RNA LPAR3 targets JPT1 via microRNA-513b-5p to facilitate glycolytic activation but repress prostate cancer radiosensitivity

A great many circular RNAs (circRNAs) are considered key modulators of human malignancies. However, the function of circRNA lysophosphatidic acid receptor 3 (LPAR3) in the radioresistance of prostate cancer (PCa) cells is still uncertain. circLPAR3, microRNA (miR)-329-3p, and JPT1 expression in PCa tissues and cells were detected by real-time quantitative PCR or western blot. Cell proliferation was detected by CCK-8 (cell proliferation assay) and colony formation assay, apoptosis was by flow cytometry, and migration and invasion ability were by Transwell assay. Cell glycolysis was analyzed by glucose uptake, lactate production, and ATP metabolism. Under different doses of radiation, the radiosensitivity of PCa cells was detected by colony formation assay. The relationship between circLPAR3, miR-513b-5p, and JPT1 was confirmed by dual luciferase reporter gene detection and RIP assay. The data presented that circLPAR3 and JPT1 expression was elevated in PCa, while miR-513b-5p expression was reduced. Repression of circLPAR3 depressed cell advancement, and restrained glycolysis, but enhanced the radiosensitivity of PCa cells. CircLPAR3's target miRNA was miR-513b-5p which targeted JPT1. Elevated JPT1 reversed the repressive effects of circLPAR3 knockdown or miR-513b-5p overexpression on PCa advancement, glycolysis, and radiosensitivity. In summary, the knockdown of circLPAR3 reduces glycolysis, but promotes PCa radiosensitivity via the miR-513b-5p/JPT1 axis, discovering a novel mechanism in PCa progression.

Reversing lung cancer radioresistance by hyperpermeable tellurium nanotherapeutics via remodeling tumor microenvironment

Tolerance to radiotherapy is the main cause of radiotherapy failure in patients with lung cancer. The key to successful treatment is to find effective targets and signaling pathways to reverse radioresistance. Based on the importance of the epidermal growth factor receptor (EGFR) signaling pathway and mitochondria in lung cancer, we developed an EGFR/mitochondrial dual-targeting radiosensitizer (M-TeNSs@Ge-11) based on tellurium nanostars to overcome radioresistance in lung cancer. The as-prepared M-TeNSs@Ge-11 nanosystem successfully located in the mitochondria not only increased the accumulation and penetration of the Te nanosystem in radiotherapy-tolerant lung cancer cells but also enhanced the sensitivity of A549 cells to X-rays, leading to excellent anticancer efficacy via overproduction of reactive oxygen species and mitochondrial dysfunction. Consistently, using unilateral and bilateral tumor models, we confirmed that M-TeNSs@Ge-11 combined with X-ray irradiation had a high therapeutic effect and could reshape the tumor immune microenvironment by affecting the infiltration of some specific immune cells, such as M2 macrophages and natural killer cells. Taken together, our study highlights a facile design strategy for Te-based nanoradiosensitizers to reverse the radiation resistance of lung cancer. Furthermore, the findings provide novel insights into their application in theranostics in cancer medicine.

Exosomal miR-196a-5p enhances radioresistance in lung cancer cells by downregulating NFKBIA.

Radiation therapy is recognized as an effective modality in the treatment of lung cancer, but radioresistance resulting from prolonged treatment reduces the chances of recovery. MicroRNAs (miRNAs) play a pivotal role in radiotherapy immunity. In this study, we aimed to investigate the mechanism by which miR-196a-5p affects radioresistance in lung cancer. The radioresistant lung cancer cell line A549R26-1 was established by radiation treatment. Cancer-associated fibroblasts (CAFs) and normal fibroblasts (NFs) were observed by microscopy, and the expression levels of CAF-specific marker proteins were detected by immunofluorescence. The shape of the exosomes was observed by electron microscopy. A CCK-8 assay was used to detect cell viability, while clone formation assays were used to detect cell proliferative capacity. Flow cytometry was performed to investigate apoptosis. The binding of miR-196a-5p and NFKBIA was predicted and further verified by the dual luciferase reporter experiment. qRT-PCR and western blotting were used to detect gene mRNA and protein levels. We found that exosomes secreted by CAFs could enhance lung cancer cell radioresistance. Moreover, miR-196a-5p potentially bound to NFKBIA, promoting malignant phenotypes in radioresistant cells. Furthermore, exosomal miR-196a-5p derived from CAFs increased radiotherapy immunity in lung cancer. Exosomal miR-196a-5p derived from CAFs enhanced radioresistance in lung cancer cells by downregulating NFKBIA, providing a new potential target for the treatment of lung cancer.

Cancer-Associated Fibroblasts Exposed to High-Dose Ionizing Radiation Promote M2 Polarization of Macrophages, Which Induce Radiosensitivity in Cervical Cancer

Radiotherapy, including brachytherapy, is a major therapeutic regimen for cervical cancer. Radioresistance is a decisive factor in radiation treatment failure. Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) in the tumor microenvironment are critical factors in the curative effects of cancer therapies. However, the interactions between TAMs and CAFs in the context of ionizing radiation are not fully understood. This study was undertaken to investigate whether M2 macrophages induce radioresistance in cervical cancer and to explore the TAMs' phenotypic transformation after IR and its underlying mechanisms. The radioresistance of cervical cancer cells was enhanced after being co-cultured with M2 macrophages. TAMs tended to undergo M2 polarization after high-dose irradiation, which was strongly associated with CAFs in both mouse models and patients with cervical cancer. Additionally, cytokine and chemokine analysis was performed to find that high-dose irradiated CAFs promoted macrophage polarization towards the M2 phenotype through chemokine (C-C motif) ligand 2. Collectively, our results highlight the crucial role that high-dose irradiated CAFs play in the regulation of M2 phenotype polarization, which ultimately induces radioresistance in cervical cancer.

Insights into the characteristics of primary radioresistant cervical cancer using single-cell transcriptomics

Radioresistance is a major cause of radiotherapy failure among patients with cervical cancer (CC), the fourth most common cause of cancer mortality in women worldwide. Traditional CC cell lines lose intra-tumoral heterogeneity, posing a challenge for radioresistance research. Meanwhile, conditional reprogramming (CR) maintains intra-tumoral heterogeneity and complexity, as well as the genomic and clinical characteristics of original cells and tissues. Three radioresistant and two radiosensitive primary CC cell lines were developed under CR conditions from patient specimens, and their characteristics were verified via immunofluorescence, growth kinetics, clone forming assay, xenografting, and immunohistochemistry. The CR cell lines had homogenous characteristics with original tumor tissues and maintained radiosensitivity in vitro and in vivo, while also maintaining intra-tumoral heterogeneity according to single-cell RNA sequencing analysis. Upon further investigation, 20.83% of cells in radioresistant CR cell lines aggregated in the G2/M cell cycle phase, which is sensitive to radiation, compared to 38.1% of cells in radiosensitive CR cell lines. This study established three radioresistant and two radiosensitive CC cell lines through CR, which will benefit further research investigating radiosensitivity in CC. Our present study may provide an ideal model for research on development of radioresistance and potential therapeutic targets in CC.

Correction to: MiR-139 Affects Radioresistance in Esophageal Cancer by Targeting the PDK1/AKT/Cyclin D1 Signaling Pathway

Correction to: MiR-139 Affects Radioresistance in Esophageal Cancer by Targeting the PDK1/AKT/Cyclin D1 Signaling Pathway

Profiling of Tumor Cell‐Delivered Exosome by Surface Enhanced Raman Spectroscopy‐Based Biosensor for Evaluation of Nasopharyngeal Cancer Radioresistance (Adv. Healthcare Mater. 8/2023)

Profiling of Tumor Cell‐Delivered Exosome by Surface Enhanced Raman Spectroscopy‐Based Biosensor for Evaluation of Nasopharyngeal Cancer Radioresistance (Adv. Healthcare Mater. 8/2023)

Euchromatic histone lysine methyltransferase 2 facilitates radioresistance in prostate cancer by repressing endoplasmic reticulum protein 29 transcription.

Prostate cancer is one of the most common cancers in men. This study was conducted to investigate the role of euchromatic histone lysine methyltransferase 2 (EHMT2) and endoplasmic reticulum protein 29 (ERP29) in the progression of radioresistance in prostate cancer. The expression of EHMT2 and ERP29 in prostate cancer cells and during the progression of radioresistance was detected using quantitative reverse transcription-polymerase chain reaction and western blotting, and the interaction between EHMT2 and ERP29 was investigated. The proliferation of transfected cells under x-ray irradiation was determined using the methyl thiazolyl tetrazolium and colony formation assays. Flow cytometry was used to analyze the apoptosis of the transfected cells under x-ray irradiation. Nude mice were subcutaneously injected with prostate cancer (DU145) cells stably transfected with sh-ERP29 or sh-NC. The effect of ERP29 expression on radioresistance in nude mice was assessed by x-ray irradiation. The expression of EHMT2 was upregulated and that of ERP29 was downregulated in prostate cancer cells during radioresistance progression. EHMT2 downregulation suppressed radioresistance in DU145 and androgen-sensitive prostate cancer (LNCaP) cells. In irradiated DU145 cells, EHMT2 inhibition decreased the number of colonies and accelerated apoptosis. The transcription of ERP29 was suppressed by EHMT2 by upregulating H3K9me2 and downregulating H3K4me3, thereby regulating radioresistance in prostate cancer cells. In addition, the downregulation of ERP29 promoted the progression of radioresistance in prostate cancer cells in nude mice. EHMT2 promotes radioresistance in prostate cancer cells by repressing ERP29 transcription.