Macroautophagy/autophagy promotes resistance to KRASG12D-targeted therapy through glutathione synthesis.

KRASG12D mutation-driven pancreatic ductal adenocarcinoma (PDAC) represents a major challenge in medicine due to late diagnosis and treatment resistance. Here, we report that macroautophagy (hereafter autophagy), a cellular degradation and recycling process, contributes to acquired resistance against novel KRASG12D-targeted therapy. The KRASG12D protein inhibitor MRTX1133 induces autophagy in KRASG12D-mutated PDAC cells by blocking MTOR activity, and increased autophagic flux prevents apoptosis. Mechanistically, autophagy facilitates the generation of glutamic acid, cysteine, and glycine for glutathione synthesis. Increased glutathione levels reduce reactive oxygen species production, which impedes CYCS translocation from mitochondria to the cytosol, ultimately preventing the formation of the APAF1 apoptosome. Consequently, genetic interventions (utilizing ATG5 or BECN1 knockout) or pharmacological inhibition of autophagy (with chloroquine, bafilomycin A1, or spautin-1) enhance the anticancer activity of MRTX1133 in vitro and in various animal models (subcutaneous, patient-derived xenograft, and orthotopic). Moreover, the release of histones by apoptotic cells triggers an adaptive immune response when combining an autophagy inhibitor with MRTX1133 in immunocompetent mice. These findings establish a new strategy to overcome KRASG12D-targeted therapy resistance by inhibiting autophagy-dependent glutathione synthesis.

Predicting the overall survival and progression-free survival of nasopharyngeal carcinoma patients based on hemoglobin, albumin, and globulin ratio and classical clinicopathological parameters.

BACKGROUND: Serum biomarkers have a significant impact on the prediction of treatment outcomes in patients diagnosed with nasopharyngeal carcinoma (NPC). The primary aim of this study was to develop and validate a nomogram that incorporates hemoglobin, albumin, and globulin ratio (HAGR) and clinical data to accurately forecast treatment outcomes in patients with NPC. METHODS: A total of 796 patients diagnosed with NPC were included in the study. RESULTS: The results of the multivariate Cox analysis revealed that TNM stage and HAGR were found to be significant independent prognostic factors for OS and PFS. Furthermore, the utilization of the nomogram demonstrated a significant improvement in the evaluation of OS, PFS compared with the eighth TNM staging system. Additionally, the implementation of Kaplan-Meier curves and decision curve analysis curves further confirmed the discriminability and clinical effectiveness of the nomogram. CONCLUSIONS: The HAGR, an innovative prognostic factor grounded in the realm of immunonutrition, has emerged as a promising prognostic marker for both OS and PFS in individuals afflicted with NPC.

Nomograms based on the lymphocyte-albumin-neutrophil ratio (LANR) for predicting the prognosis of nasopharyngeal carcinoma patients after definitive radiotherapy.

Much evidence has accumulated to show that inflammation and nutritional status are associated with the prognosis of patients with various cancers. The present study was designed to explore the prognostic role of the LANR in NPC patients receiving definitive radiotherapy and to construct a nomogram for predicting patient survival. This study retrospectively reviewed 805 NPC patients (604 in the training cohort and 201 in the validation cohort) who received definitive radiotherapy between January 2013 and December 2019. The clinical data and pretreatment laboratory test data, including lymphocyte count, neutrophil count, and serum ALB concentration, were collected for all patients. The LANR was calculated as the albumin × lymphocyte/neutrophil ratio. Patients in the training cohort and validation cohort were categorized into high-LANR and low-LANR groups according to the corresponding cutoff values. The independent prognostic factors for overall survival (OS), progression-free survival (PFS), relapse-free survival (RFS), and metastasis-free survival (MFS) were evaluated by univariate and multivariate Cox regression analyses, and a nomogram was subsequently constructed. The performance of the nomogram was evaluated by the concordance index (C-index) and calibration curve. A low LANR (< 14.3) was independently associated with worse OS, PFS and MFS in NPC patients. A prognostic prediction nomogram was established based on T stage, N stage, Eastern Cooperative Oncology Group (ECOG) score, treatment modality, and LANR and was validated. The C-indices of the nomograms for OS and PFS in the training cohort were 0.729 and 0.72, respectively. The C-indices of the nomograms for OS and PFS in the validation cohort were 0.694 and 0.695, respectively. The calibration curve revealed good consistency between the actual survival and the nomogram prediction. Patients with NPC with low pretreatment LANR had a poor prognosis. The nomogram established on the basis of the LANR was efficient and clinically useful for predicting survival in NPC patients who underwent definitive radiotherapy.

Prognostic significance of pan-immune-inflammation value (PIV) in nasopharyngeal carcinoma patients.

Background: Blood-based immune-inflammation indexes have been widely used to predict survival in a variety of cancers. In this research, we seeked to evaluate a novel immune-inflammation marker, named the pan-immune-inflammation value (PIV), in patients with nasopharyngeal carcinoma (NPC) undergoing definitive radiotherapy. Methods: A group of 377 patients with NPC was retrospectived analyzed. Clinical data and laboratory data were collected. Receiver operating characteristic (ROC) curve analysis was performed in order to determine the optimal PIV cut-off value. Survival curves were estimated by Kaplan-Meier method, and prognostic variables were identified using a Cox regression model. Additionally, we developed a nomogram and assessed its acuracy using the concordance index (C-index) and a calibration curve. Results: The optimal PIV cut-off value was 146.24 according to ROC analysis. High PIV was related to poorer Eastern Cooperative Oncology Group Performance Status (ECOG PS) score (p = 0.017), more advanced T (p＜0.001) and clinical stages (p = 0.024). In univariate analysis, older Age, poorer ECOG PS, higher Epstein-Barr virus DNA (EBV-DNA), advanced T, N and clinical stage, and higher PIV levels were related to patients' poorer overall survival (OS). Poorer ECOG PS, higher EBV-DNA, later T stage, later clinical stage, and higher PIV were associated with patients' poorer progression free survival (PFS). Male sex and later T stage were associated with patients' poorer locoregional recurrence free survival (LRRFS). Poorer ECOG PS, higher EBV-DNA, later T stage, later clinical stage, and higher PIV were associated with patients' poorer distant metastasis free survival (DMFS). Multivariate analysis demonstrated that PIV was an independent prognostic index for OS (HR 2.231, 95 % CI 1.241-4.011, P = 0.007), PFS (HR 1.664, 95 % CI 1.003-2.760, P = 0.049), and DMFS(HR 2.081, 95 % CI 1.071-4.044, P = 0.031). Nomogram C-indexes for the nomogram of OS were 0.684, and PFS were 0.62, respectively. Survival predictions and actual survival were consistent according to the calibration curve. Conclusions: Pre-treatment PIV is a promising biomarker for predicting survival in patients with NPC.

Prognostic value of the fibrinogen albumin ratio index (FARI) in nasopharyngeal carcinoma patients undergoing radiotherapy.

There is mounting evidence that malnutrition and systemic inflammation status are involved in the prognosis of various cancers. In this study, we aimed to evaluate the prognostic value of the pretreatment fibrinogen-albumin ratio index (FARI) in nasopharyngeal carcinoma (NPC) patients receiving definite radiotherapy. NPC patients who received definite radiotherapy between January 2013 and December 2019 were included. A receiver operating characteristic (ROC) curve was used to determine the optimal cutoff value. The clinicopathological characteristics of the patients were compared via the Chi-square test. Survival curves were analyzed by the Kaplan‒Meier method. The prognostic factors were evaluated by univariate and multivariate analyses via Cox hazards regression analysis. A total of 225 patients were enrolled, and the median follow-up time was 48.5 months. High FARI was correlated with worse ECOG score (p = 0.003), higher EBV-DNA titer (p = 0.047), and more advanced clinical stage (p < 0.001). In the multivariable analysis, FARI independently predicted OS (HR 2.399, 95% CI 1.294-4.450, P < 0.001), PFS (HR 2.085, 95% CI 1.200-3.625, P = 0.009), and DMFS (HR 2.527, 95% CI 1.288-4.958, P < 0.001). The current findings suggest that a high pretreatment FARI is an independent predictor of OS, PFS and DMFS in NPC patients undergoing definite radiotherapy.

GPX4 in cell death, autophagy, and disease.

Selenoprotein GPX4 (glutathione peroxidase 4), originally known as PHGPX (phospholipid hydroperoxide glutathione peroxidase), is the main oxidoreductase in the use of glutathione as a reducing agent in scavenging lipid peroxidation products. There are three GPX4 isoforms: cytosolic (cGPX4), mitochondrial (mGPX4), and nuclear (nGPX4), with distinct spatiotemporal expression patterns during embryonic development and adult life. In addition to inducing the main phenotype of ferroptosis, the loss of GPX4 can in some cells trigger apoptosis, necroptosis, pyroptosis, or parthanatos, which mediates or accelerates developmental defects, tissue damage, and sterile inflammation. The interaction of GPX4 with the autophagic degradation pathway further modulates cell fate in response to oxidative stress. Impaired GPX4 function is implicated in tumorigenesis, neurodegeneration, infertility, inflammation, immune disorders, and ischemia-reperfusion injury. Additionally, the R152H mutation in GPX4 can promote the development of Sedaghatian-type spinal metaphyseal dysplasia, a rare and fatal disease in newborns. Here, we discuss the roles of classical GPX4 functions as well as emerging GPX4-regulated processes in cell death, autophagy, and disease.Abbreviations: AA: arachidonic acid; cGPX4: cytosolic GPX4; CMA: chaperone-mediated autophagy; DAMPs: danger/damage-associated molecular patterns; mGPX4: mitochondrial GPX4; nGPX4: nuclear GPX4; GSDMD-N: N-terminal fragment of GSDMD; I/R: ischemia-reperfusion; PLOOH: phospholipid hydroperoxide; PUFAs: polyunsaturated fatty acids; RCD: regulated cell death; ROS: reactive oxygen species; Se: selenium; SSMD: Sedaghatian-type spondylometaphyseal dysplasia; UPS: ubiquitin-proteasome system.

Autophagy-dependent ferroptosis as a potential treatment for glioblastoma.

Glioblastoma (GBM) is the most common malignant primary brain tumor with a poor 5-year survival rate. Autophagy is a conserved intracellular degradation system that plays a dual role in GBM pathogenesis and therapy. On one hand, stress can lead to unlimited autophagy to promote GBM cell death. On the other hand, elevated autophagy promotes the survival of glioblastoma stem cells against chemotherapy and radiation therapy. Ferroptosis is a type of lipid peroxidation-mediated regulated necrosis that initially differs from autophagy and other types of cell death in terms of cell morphology, biochemical characteristics, and the gene regulators involved. However, recent studies have challenged this view and demonstrated that the occurrence of ferroptosis is dependent on autophagy, and that many regulators of ferroptosis are involved in the control of autophagy machinery. Functionally, autophagy-dependent ferroptosis plays a unique role in tumorigenesis and therapeutic sensitivity. This mini-review will focus on the mechanisms and principles of autophagy-dependent ferroptosis and its emerging implications in GBM.

TMEM164 is a new determinant of autophagy-dependent ferroptosis.

Macroautophagy (hereafter "autophagy") is a membrane-mediated biological process that involves engulfing and delivering cytoplasmic components to lysosomes for degradation. In addition to autophagy's pro-survival effect during nutrient starvation, excessive activation of autophagy machinery can also cause regulated cell death, especially iron-dependent ferroptosis. Here, we report a key role of TMEM164 (transmembrane protein 164) in selectively mediating ATG5 (autophagy related 5)-dependent autophagosome formation during ferroptosis, rather than during starvation. In contrast, the membrane protein ATG9A (autophagy-related 9A) is dispensable for the formation of autophagosomes during ferroptosis. TMEM164-mediated autophagy degrades ferritin, GPX4 (glutathione peroxidase 4), and lipid droplets to increase iron accumulation and lipid peroxidation, thereby promoting ferroptotic cell death. Consequently, the loss of TMEM164 limits the anticancer activity of ferroptosis-mediated cytotoxicity in mice. High TMEM164 expression is associated with improved survival and increased immune cell infiltration in patients with pancreatic cancer. These findings establish a new mode of autophagy-dependent ferroptosis.

A noncanonical function of EIF4E limits ALDH1B1 activity and increases susceptibility to ferroptosis.

Ferroptosis is a type of lipid peroxidation-dependent cell death that is emerging as a therapeutic target for cancer. However, the mechanisms of ferroptosis during the generation and detoxification of lipid peroxidation products remain rather poorly defined. Here, we report an unexpected role for the eukaryotic translation initiation factor EIF4E as a determinant of ferroptotic sensitivity by controlling lipid peroxidation. A drug screening identified 4EGI-1 and 4E1RCat (previously known as EIF4E-EIF4G1 interaction inhibitors) as powerful inhibitors of ferroptosis. Genetic and functional studies showed that EIF4E (but not EIF4G1) promotes ferroptosis in a translation-independent manner. Using mass spectrometry and subsequent protein-protein interaction analysis, we identified EIF4E as an endogenous repressor of ALDH1B1 in mitochondria. ALDH1B1 belongs to the family of aldehyde dehydrogenases and may metabolize the aldehyde substrate 4-hydroxynonenal (4HNE) at high concentrations. Supraphysiological levels of 4HNE triggered ferroptosis, while low concentrations of 4HNE increased the cell susceptibility to classical ferroptosis inducers by activating the NOX1 pathway. Accordingly, EIF4E-dependent ALDH1B1 inhibition enhanced the anticancer activity of ferroptosis inducers in vitro and in vivo. Our results support a key function of EIF4E in orchestrating lipid peroxidation to ignite ferroptosis.

Lower Expression of TWEAK is Associated with Poor Survival and Dysregulate TIICs in Lung Adenocarcinoma.

Background: Lung cancer remains the leading cause of cancer death worldwide, and the most subtype is lung adenocarcinoma (LUAD). Tumor-infiltrating immune cells (TIICs) greatly impact the prognosis of LUAD. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK), signal via its receptor fibroblast growth factor-inducible 14 (Fn14), dysregulates immune cell recruitment within tumor environment, thus promoting the progression of autoimmune diseases and cancer. We aimed to explore its role in LUAD. Methods: The expression level of TWEAK was explored in Tumor Immune Estimation Resource 2.0 (TIMER2.0) and Oncomine databases. The Tumor Immune Dysfunction and Exclusion (TIDE) and Lung Cancer Explorer (LCE) databases were applied to evaluate the survival in correlation to TWEAK expression. TIICs were assessed with TIMER2.0 and TIDE datasets. The expression of TWEAK protein was detected in LUAD cell lines and also in tissue samples from LUAD patients via western blotting or combination with immunochemistry. Results: Our results showed that TWEAK was downregulated in LUAD tumors compared to normal tissues in TIMER2.0, Oncomine, cell lines, and clinical specimens. Poor survival was uncovered in lower TWEAK expression of LUAD patients in LCE (meta - HR = 0.84 [95% CI, 0.76-0.92]) and TCGA (Continuous Z = -1.97, p = 0.0486) and GSE13213@PRECOG (Continuous Z = -4.25, p = 2.12e - 5) in TIDE. Multiple tumor-infiltrating immune cells (TIICs) were found closely correlated with TWEAK expression in LUAD, especially hematopoietic stem cell (Rho = 0.505, p = 2.78e - 33), common lymphoid progenitor (Rho = -0.504, p = 3.79e - 33), and myeloid-derived suppressor cells (MDSCs) (Rho = -0.615, p = 1.36e - 52). Conclusion: Lower level of TWEAK was linked with poor survival and aberrant recruitment and phenotype of TIICs in LUAD, which might motivate immune escape and weaken the effects of immunotherapy.

High fibrinogen-albumin ratio index (FARI) predicts poor survival in head and neck squamous cell carcinoma patients treated with surgical resection.

PURPOSE: The aim of the present study was to investigate the predictive value of the fibrinogen/albumin ratio index (FARI), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) on the prognosis of patients with operable head and neck squamous cell carcinoma (HNSCC). METHODS: A cohort of 155 operable HNSCC patients were enrolled. Laboratory and clinical data were extracted from the patients' electronic medical record. The optimal cut-off values were determined by receiver operating characteristic (ROC) curves analysis. Clinicopathological characteristics of patients were compared via Chi-square test. Survival curves were analyzed by Kaplan-Meier method. The prognostic factors were evaluated by univariate and multivariate analyses via the Cox hazards regression analysis. RESULTS: The median follow-up time was 31.7 months. An increased level of NLR was associated with later T stages, later N stages, and more advanced clinical stages(all P < 0.05). On univariate analyses, FARI, NLR, PLR, and N stage were correlated with progression-free survival (PFS) (all P < 0.05) as well as overall survival (OS) (all P < 0.05). And the clinical stage was only relevant to OS (P = 0.007). Multivariate Cox regression analysis revealed that FARI (HR 3.486, 95% CI 2.086-5.825, P < 0.001; HR 4.474, 95% CI 2.442-8.199, P < 0.001), NLR (HR 3.163, 95% CI 1.810-5.528, P < 0.001; HR 3.690, 95% CI 1.955-6.963, P < 0.001), and N stage (HR 1.718, 95% CI 1.058-2.789, P = 0.029; HR 1.777, 95% CI 1.024-3.084, P = 0.041) were independent prognostic factors for PFS and OS. CONCLUSION: Our findings indicate that FARI and NLR are effective and convenient markers for predicting prognosis in operable HNSCC patients.

Clinicopathological Significance of ATRX Expression in Nasopharyngeal Carcinoma Patients: A Retrospective Study.

Background: Nasopharyngeal carcinoma (NPC) is the most common head and neck squamous cell carcinoma in south China. Radiation technology improves the local control rates in early NPC. However, the distant metastases are still the main cause of treatment failure. Thus, to find biomarkers for prognosis will help to enhance the survival of NPC. ATRX is a chromatin remodeling protein localized in the nucleus. Deletion or mutation of ATRX gene has been demonstrated in a variety of malignancies. However, the significance of ATRX expression in the prognosis of NPC remains unclear. Methods: Tumor tissues from 227 NPC patients diagnosed in the Second Xiangya Hospital of Central South University from 2011 to 2016 were selected. Immunohistochemistry was used to detect the ATRX expression level of the tumor tissue. Chi-square test was used to analyze the relationship between ATRX expression and clinical characteristics such as age, sex, T stage, N stage and clinical stage. Kaplan-Meier method was used for survival analysis, and log-rank was used to compare the difference in survival rate. Results: There were 53 patients with negative ATRX expression, accounting for 24.2% of the total group. ATRX expression was not significantly associated with age, sex, N stage, clinical stage, and progression-free survival (PFS) (P>0.05). However, patients with negative ATRX expression had earlier T staging (P=0.045) and a higher 5-year overall survival (84.9% vs 66.9%, P=0.022). Conclusions: Loss of ATRX expression may contribute to better prognosis in patients with NPC.

Corrigendum: Alpha Thalassemia/Intellectual Disability X-Linked Deficiency Sensitizes Non-Small Cell Lung Cancer to Immune Checkpoint Inhibitors.

[This corrects the article DOI: 10.3389/fonc.2020.608300.].

Mitophagy in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC), one of the most aggressive solid malignancies, is characterized by the presence of oncogenic KRAS mutations, poor response to current therapies, prone to metastasis, and a low 5-year overall survival rate. Macroautophagy (herein referred to as autophagy) is a lysosome-dependent degradation system that forms a series of dynamic membrane structures to engulf, degrade, and recycle various cargoes, such as unused proteins, damaged organelles, and invading pathogens. Autophagy is usually upregulated in established cancers, but it plays a dual role in the regulation of the initiation and progression of PDAC. As a type of selective autophagy, mitophagy is a mitochondrial quality control mechanism that uses ubiquitin-dependent (e.g., the PINK1-PRKN pathway) and -independent (e.g., BNIP3L/NIX, FUNDC1, and BNIP3) pathways to regulate mitochondrial turnover and participate in the modulation of metabolism and cell death. Genetically engineered mouse models indicate that the loss of PINK1 or PRKN promotes, whereas the depletion of BNIP3L inhibits oncogenic KRAS-driven pancreatic tumorigenesis. Mitophagy also play a dual role in the regulation of the anticancer activity of certain cytotoxic agents (e.g., rocaglamide A, dichloroacetate, fisetin, and P. suffruticosa extracts) in PDAC cells or xenograft models. In this min-review, we summarize the latest advances in understanding the complex role of mitophagy in the occurrence and treatment of PDAC.

MGST1 is a redox-sensitive repressor of ferroptosis in pancreatic cancer cells.

Ferroptosis is a type of nonapoptotic cell death driven by lipid peroxidation. Here, we show a key role of MGST1 in inhibiting ferroptosis in cell cultures and mouse xenograft models. Ferroptosis activators induce MGST1 upregulation in human pancreatic ductal adenocarcinoma (PDAC) cell lines in an NFE2L2-dependent manner. The genetic depletion of MGST1 or NFE2L2 has a similar effect in promoting ferroptosis, whereas the re-expression of MGST1 restores the resistance of NFE2L2-knockdown cells to ferroptosis. MGST1 inhibits ferroptotic cancer cell death partly by binding to ALOX5, resulting in reduced lipid peroxidation. The expression of MGST1 is positively correlated with NFE2L2 expression in pancreatic tumors, which is implicated in the poor prognosis of patients with PDAC. These findings not only provide a valuable insight into the defense mechanism against ferroptotic cell death, but also indicate that targeting the MGST1 redox-sensitive pathway may be a promising strategy for the treatment of PDAC.

PDK4 dictates metabolic resistance to ferroptosis by suppressing pyruvate oxidation and fatty acid synthesis.

Although induction of ferroptosis, an iron-dependent form of non-apoptotic cell death, has emerged as an anticancer strategy, the metabolic basis of ferroptotic death remains poorly elucidated. Here, we show that glucose determines the sensitivity of human pancreatic ductal carcinoma cells to ferroptosis induced by pharmacologically inhibiting system xc-. Mechanistically, SLC2A1-mediated glucose uptake promotes glycolysis and, thus, facilitates pyruvate oxidation, fuels the tricyclic acid cycle, and stimulates fatty acid synthesis, which finally facilitates lipid peroxidation-dependent ferroptotic death. Screening of a small interfering RNA (siRNA) library targeting metabolic enzymes leads to identification of pyruvate dehydrogenase kinase 4 (PDK4) as the top gene responsible for ferroptosis resistance. PDK4 inhibits ferroptosis by blocking pyruvate dehydrogenase-dependent pyruvate oxidation. Inhibiting PDK4 enhances the anticancer activity of system xc- inhibitors in vitro and in suitable preclinical mouse models (e.g., a high-fat diet diabetes model). These findings reveal metabolic reprogramming as a potential target for overcoming ferroptosis resistance.

NUPR1 is a critical repressor of ferroptosis.

Ferroptosis is a type of iron-dependent regulated cell death, representing an emerging disease-modulatory mechanism. Transcription factors play multiple roles in ferroptosis, although the key regulator for ferroptosis in iron metabolism remains elusive. Using NanoString technology, we identify NUPR1, a stress-inducible transcription factor, as a driver of ferroptosis resistance. Mechanistically, NUPR1-mediated LCN2 expression blocks ferroptotic cell death through diminishing iron accumulation and subsequent oxidative damage. Consequently, LCN2 depletion mimics NUPR1 deficiency with respect to ferroptosis induction, whereas transfection-enforced re-expression of LCN2 restores resistance to ferroptosis in NUPR1-deficient cells. Pharmacological or genetic blockade of the NUPR1-LCN2 pathway (using NUPR1 shRNA, LCN2 shRNA, pancreas-specific Lcn2 conditional knockout mice, or the small molecule ZZW-115) increases the activity of the ferroptosis inducer erastin and worsens pancreatitis, in suitable mouse models. These findings suggest a link between NUPR1-regulated iron metabolism and ferroptosis susceptibility.

The Role of the SOX9/lncRNA ANXA2P2/miR-361-3p/SOX9 Regulatory Loop in Cervical Cancer Cell Growth and Resistance to Cisplatin.

Cervical cancer is a highly prevalent female malignancy. Presently, cisplatin (DDP) is a first-line agent for cervical cancer chemotherapy. However, its curative effect is limited because of chemo-resistance. It has been previously reported that SOX9 targeted and activated oncogenic genes, enhancing cervical cancer cell resistance to DDP. The effects of the SOX9/lncRNA ANXA2P2/miR-361-3p/SOX9 regulatory loop on cervical cancer cell growth and resistance to DDP have been demonstrated. miR-361-3p expression was decreased in DDP-resistant cervical cancer cells and tissues. Moreover, miR-361-3p overexpression inhibited the growth of resistant cervical cancer cells and the resistance to DDP, whereas miR-361-3p inhibition exerted opposite effects. miR-361-3p inhibited SOX9 expression through binding; the effects of miR-361-3p inhibition were partially reversed by SOX9 knockdown. LncRNA ANXA2P2 expression was elevated in DDP-resistant cervical cancer cells and tissues. LncRNA ANXA2P2 inhibited miR-361-3p expression by binding, thereby upregulating SOX9. LncRNA ANXA2P2 knockdown inhibited DDP-resistant cervical cancer cell growth and resistance to DDP, whereas the effects of lncRNA ANXA2P2 knockdown were partially reversed by miR-361-3p inhibition. SOX9 expression was elevated in DDP-resistant cervical cancer cells and tissues, and SOX9 activated lncRNA ANXA2P2 transcription by binding. Collectively, SOX9, lncRNA ANXA2P2, and miR-361-3p form a regulatory loop, modulating DDP-resistant cervical cancer cell growth and response to DDP treatment.

Ferroptotic damage promotes pancreatic tumorigenesis through a TMEM173/STING-dependent DNA sensor pathway.

Ferroptosis is a more recently recognized form of cell death that relies on iron-mediated oxidative damage. Here, we evaluate the impact of high-iron diets or depletion of Gpx4, an antioxidant enzyme reported as an important ferroptosis suppressor, in the pancreas of mice with cerulean- or L-arginine-induced pancreatitis, and in an oncogenic Kras murine model of spontaneous pancreatic ductal adenocarcinoma (PDAC). We find that either high-iron diets or Gpx4 depletion promotes 8-OHG release and thus activates the TMEM173/STING-dependent DNA sensor pathway, which results in macrophage infiltration and activation during Kras-driven PDAC in mice. Consequently, the administration of liproxstatin-1 (a ferroptosis inhibitor), clophosome-mediated macrophage depletion, or pharmacological and genetic inhibition of the 8-OHG-TMEM173 pathway suppresses Kras-driven pancreatic tumorigenesis in mice. GPX4 is also a prognostic marker in patients with PDAC. These findings provide pathological and mechanistic insights into ferroptotic damage in PDAC tumorigenesis in mice.

Mitophagy Receptors in Tumor Biology.

Mitochondria are multifunctional organelles that regulate cancer biology by synthesizing macromolecules, producing energy, and regulating cell death. The understanding of mitochondrial morphology, function, biogenesis, fission and fusion kinetics, and degradation is important for the development of new anticancer strategies. Mitophagy is a type of selective autophagy that can degrade damaged mitochondria under various environmental stresses, especially oxidative damage and hypoxia. The key regulator of mitophagy is the autophagy receptor, which recognizes damaged mitochondria and allows them to enter autophagosomes by binding to MAP1LC3 or GABARAP, and then undergo lysosomal-dependent degradation. Many components of mitochondria, including mitochondrial membrane proteins (e.g., PINK1, BNIP3L, BNIP3, FUNDC1, NIPSNAP1, NIPSNAP2, BCL2L13, PHB2, and FKBP8) and lipids (e.g., cardiolipin and ceramides), act as mitophagy receptors in a context-dependent manner. Dysfunctional mitophagy not only inhibits, but also promotes, tumorigenesis. Similarly, mitophagy plays a dual role in chemotherapy, radiotherapy, and immunotherapy. In this review, we summarize the latest advances in the mechanisms of mitophagy and highlight the pathological role of mitophagy receptors in tumorigenesis and treatment.