Targeting the autophagy-miRNA axis in prostate cancer: toward novel diagnostic and therapeutic strategies

Since prostate cancer is one of the leading causes of cancer-related death, a better understanding of the molecular pathways guiding its development is imperative. A key factor in prostate cancer is autophagy, a cellular mechanism that affects both cell survival and death. Autophagy is essential in maintaining cellular homeostasis. Autophagy is a physiological mechanism wherein redundant or malfunctioning cellular constituents are broken down and recycled. It is essential for preserving cellular homeostasis and is implicated in several physiological and pathological conditions, including cancer. Autophagy has been linked to metastasis, tumor development, and treatment resistance in prostate cancer. The deregulation of miRNAs related to autophagy appears to be a crucial element in the etiology of prostate cancer. These miRNAs influence the destiny of cancer cells by finely regulating autophagic mechanisms. Numerous investigations have emphasized the dual function of specific miRNAs in prostate cancer, which alter autophagy-related pathways to function as either tumor suppressors or oncogenes. Notably, miRNAs have been linked to the control of autophagy and the proliferation, apoptosis, and migration of prostate cancer cells. To create customized therapy approaches, it is imperative to comprehend the dynamic interplay between autophagy and miRNAs in prostate cancer. The identification of key miRNAs provides potential diagnostic and prognostic markers. Unraveling the complex network of lncRNAs, like PCA3, also expands the repertoire of molecular targets for therapeutic interventions. This review explores the intricate interplay between autophagy and miRNAs in prostate cancer, focusing on their regulatory roles in cellular processes ranging from survival to programmed cell death.

FBP1 is a potential prognostic biomarker and correlated with tumor immunosuppressive microenvironment in glioblastoma

Hypoxia has been shown to contribute to tumor immunosuppressive microenvironment and is an effective prognostic indicator. This study aimed to screen prognostic hypoxia-related genes (HRGs) in glioblastoma and investigate the association between HRGs and tumor immunosuppressive microenvironment. The glioblastoma-related mRNA data were collected from TCGA, GEO, and CGGA databases. Totally 200 HRGs were obtained from the GSEA website. The prognostic HRGs were screened by univariate Cox regression analysis. Somatic mutation data of glioblastoma from TCGA was visualized using the "maftools" of R package. Immune cell infiltration proportions were calculated by CIBERSORT. The TISIDB online tool was applied to analyze the relationship between HRGs and immunoinhibitors as well as the HRG expression in different glioblastoma immune and molecular subtypes. Hub gene's mRNA and protein levels in cell lines were determined by qRT-PCR and western blot, respectively. The effects of hub gene knockdown on cell viability and migration ability were evaluated employing CCK8 and wound healing assays. The univariate Cox regression showed that high level of FBP1 (fructose-1,6-bisphosphatase 1) was a poor prognostic biomarker, and FBP1 was mainly expressed in lymphocyte depleted immune subtype of glioblastoma. High FBP1 mRNA and protein levels have been successfully validated in vitro. The somatic mutation analysis suggested that TP53 mutation rate was the highest in the high FBP1 glioblastoma group, while EGFR mutation rate was the highest in the low FBP1 glioblastoma group. In the high FBP1 group, the infiltration proportions and types of immune cells were less, dominated by macrophages M2, and the expression of CTLA4, LAG3, TIGIT, PDL1, and PDL2 was significantly upregulated. The expression of FBP1 was positively correlated with several immunoinhibitors, such as IL-10 and TGFβ-1. In conclusion, we demonstrated that FBP1 could serve as a prognostic biomarker for glioblastoma. The immune microenvironment in the high FBP1 group might be suppressed by up-regulating immune checkpoints and immunoinhibitors.

Regulation of self-renewal in ovarian cancer stem cells by fructose via chaperone-mediated autophagy

The chaperone-mediated autophagy (CMA) pathway is deregulated in different types of cancers; however, its role in cancer stem cells (CSCs) is unknown yet. Development of ovarian cancer, the most lethal gynecological type of cancer, involves the metastasis of CSCs to the abdominal cavity. This study aims to determine the role of CMA in ovarian CSCs. We found that the transcription factor EB (TFEB) and trehalose, a disaccharide that induces TFEB activation, enhance the expression of octamer-binding transcription factor 4 (OCT4) stem cell and lysosomal-associated membrane protein 2A (LAMP2A) CMA markers. However, trehalose did not increase the level of the LC3II macroautophagy marker in ovarian CSCs. In A2780 and SKOV3 ovarian CSCs, LAMP2A and heat shock protein 70 (HSC70) exhibited higher expression levels than in normal adherent cells. Our results showed that the silencing of the LAMP2A gene resulted in reduced sphere formation and enhanced GLUT5 expression in ovarian CSCs. Moreover, the treatment with fructose reduced sphere formation and enhanced the expression levels of LAMP2A, SOX2, and OCT4 in ovarian CSCs. The KEGG functional analysis revealed that differentially expressed genes were enriched in the ferroptosis pathway in A2780-spheroid (SP) cells after treatment with fructose. In A2780-SP and SKOV3-SP cells, the level of SLC7A11 decreased whereas FTH increased after treatment with fructose. Taken together, our results suggest that CMA is mediated in CSCs via fructose metabolism.

Immune-related gene index predicts metastasis for prostate cancer patients undergoing radical radiotherapy

In this study, we established a novel immunologic gene prognostic index (IGPI) to predict metastasis and provided new insights into tumor immune microenvironment (TIME) for PCa patients receiving radical radiotherapy. GBP2 and IGF1 were independent factors associated with metastasis-free survival. IGPI score was calculated based on GBP2 and IGF1 and this score was an independent risk factor for PCa patients undergoing radical radiotherapy. Patients with higher IGPI score were at higher risk of metastasis and biochemical recurrence, which were externally validated in the TCGA database and other GEO datasets. IGPI score had demonstrated moderate diagnostic ability of radiation resistance (AUC: 0.889). This score increased with the augment of Gleason score and T stage, as well as biochemical recurrence. Using EPIC, ESTIMATE and immunophenoscore (IPS) algorithms, cancer associated fibroblasts (CAFs), macrophages, stromal score, and estimate score were significantly higher in patients with metastasis group compared to their counterpart. Besides, for CAFs, macrophages, stromal score, and estimate score, patients with higher scores were at higher risk of metastasis, and the HRs were 3.65, 4.01, 4.27, and 3.78, respectively. IGPI score was highly positively associated with stromal score (coefficient: 0.39), immune score (coefficient: 0.43), estimate score (coefficient: 0.45), CAFs (coefficient: 0.42) and macrophages (coefficient: 0.42), while showing the opposite relationship with tumor purity (coefficient: - 0.45). In conclusion, we found that IGPI based on GBP2 and IGF1 might serve as a biomarker predicting metastasis for PCa patients. Besides, the current data further highlight the importance of CAFs in the metastatic process of PCa.

Revisited Metabolic Control and Reprogramming Cancers by Means of the Warburg Effect in Tumor Cells

Aerobic glycolysis is an emerging hallmark of many human cancers, as cancer cells are defined as a “metabolically abnormal system”. Carbohydrates are metabolically reprogrammed by its metabolizing and catabolizing enzymes in such abnormal cancer cells. Normal cells acquire their energy from oxidative phosphorylation, while cancer cells acquire their energy from oxidative glycolysis, known as the “Warburg effect”. Energy–metabolic differences are easily found in the growth, invasion, immune escape and anti-tumor drug resistance of cancer cells. The glycolysis pathway is carried out in multiple enzymatic steps and yields two pyruvate molecules from one glucose (Glc) molecule by orchestral reaction of enzymes. Uncontrolled glycolysis or abnormally activated glycolysis is easily observed in the metabolism of cancer cells with enhanced levels of glycolytic proteins and enzymatic activities. In the “Warburg effect”, tumor cells utilize energy supplied from lactic acid-based fermentative glycolysis operated by glycolysis-specific enzymes of hexokinase (HK), keto-HK-A, Glc-6-phosphate isomerase, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase, phosphofructokinase (PFK), phosphor-Glc isomerase (PGI), fructose-bisphosphate aldolase, phosphoglycerate (PG) kinase (PGK)1, triose phosphate isomerase, PG mutase (PGAM), glyceraldehyde-3-phosphate dehydrogenase, enolase, pyruvate kinase isozyme type M2 (PKM2), pyruvate dehydrogenase (PDH), PDH kinase and lactate dehydrogenase. They are related to glycolytic flux. The key enzymes involved in glycolysis are directly linked to oncogenesis and drug resistance. Among the metabolic enzymes, PKM2, PGK1, HK, keto-HK-A and nucleoside diphosphate kinase also have protein kinase activities. Because glycolysis-generated energy is not enough, the cancer cell-favored glycolysis to produce low ATP level seems to be non-efficient for cancer growth and self-protection. Thus, the Warburg effect is still an attractive phenomenon to understand the metabolic glycolysis favored in cancer. If the basic properties of the Warburg effect, including genetic mutations and signaling shifts are considered, anti-cancer therapeutic targets can be raised. Specific therapeutics targeting metabolic enzymes in aerobic glycolysis and hypoxic microenvironments have been developed to kill tumor cells. The present review deals with the tumor-specific Warburg effect with the revisited viewpoint of recent progress.

AMPK's double-faced role in advanced stages of prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer deaths in men. Unfortunately, a very limited number of drugs are available for the relapsed and advanced stages of PCa, adding only a few months to survival; therefore, it is vital to develop new drugs. 5´ AMP-activated protein kinase (AMPK) is a master regulator of cell metabolism. It plays a significant role in the metabolism of PCa; hence, it can serve well as a treatment option for the advanced stages of PCa. However, whether this pathway contributes to cancer cell survival or death remains unknown. The present study reviews the possible pathways by which AMPK plays role in the advanced stages of PCa, drug resistance, and metastasis: (1) AMPK has a contradictory role in promoting glycolysis and the Warburg effect which are correlated with cancer stem cells (CSCs) survival and advanced PCa. It exerts its effect by interacting with hypoxia-induced factor 1 (HIF1) α, pyruvate kinase 2 (PKM2), glucose transporter (GLUT) 1 and pyruvate dehydrogenase complex (PDHC), which are key regulators of glycolysis; however, whether it promotes or discourage glycolysis is not conclusive. It can also exert an anti-CSC effect by negative regulation of NANOG and epithelial-mesenchymal transition (EMT) transcription factors, which are the major drivers of CSC maintenance; (2) the regulatory effect of AMPK on autophagy is also noticeable. Androgen receptors' expression increases AMPK activation through Calcium/calmodulin-dependent protein kinase 2 (CaMKK2) and induces autophagy. In addition, AMPK itself increases autophagy by downregulating the mammalian target of rapamycin complex (mTORC). However, whether increased autophagy inhibits or promotes cell death and drug resistance is contradictory. This study reveals that there are numerous pathways other than cell metabolism by which AMPK exerts its effects in the advanced stages of PCa, making it a priceless treatment target. Finally, we mention some drugs developed to treat the advanced stages of PCa by acting on AMPK.

Knockdown of MAGE-A6 enhanced the irradiation sensitivity of non-small cell lung cancer cells by activating the AMPK pathway

Non-small cell lung cancer is a common respiratory tumor. The mortality rate of lung cancer patients has continued to rise in recent years. Several studies revealed that the expression of melanoma antigen 6 (MAGE-A6) promoted the development of multiple types of cancer. In addition, the suppression of AMPK pathway could restrict the radiosensitization of prostate cancer cells. Inhibition of MAGE-A6 activated the AMPK pathway in colorectal cancer cells. However, whether the MAGE-A6 could regulate the radiosensitivity of non-small cell lung cancer cells by regulating of the AMPK pathway is unclear. In this study, we established the MAGE-A6 knockdown in A549 and H1299 cells. Next, the apoptosis and proliferation of these cells were detected by the flow cytometry analysis and colony formation assay after the irradiation, respectively. Then, the expression of p-AMPKα1 and p-S6K1 in these cells was explored by the western blotting. After that, we inhibited the expression of AMPKα1 in MAGE-A6 knockdown cells. The proliferation and apoptosis of these cells were detected with colony formation assay and flow cytometry analysis. Finally, the tumor formation of these cells was detected in nude mice. Our results showed that inhibition of MAGE-A6 suppressed the proliferation and aggravated the apoptosis of A549 and H1299 cells after the irradiation. Knockdown of MAGE-A6 activated the expression of p-AMPKα1 and repressed the expression of p-S6K1 in these cells. Suppression of AMPKα1 in MAGE-A6 knockdown cells abolished these effects. Knockdown of MAGE-A6 also enhanced the radiosensitivity of these cells in vivo. These results suggested that inhibition of MAGE-A6 promoted the radiosensitivity of non-small cell lung cancer cells by activating AMPK pathway. Therefore, MAGE-6 has the potential to be explored as the therapeutic target for the treatment of non-small cell lung cancer in clinical.

Expression status and prognostic value of autophagy-related lncRNAs in prostate cancer

BACKGROUND

LncRNAs involve in the autophagy to regulate Prostate cancer (PCa) initiation and progression. Therefore, it urges to explore more significant AR-lncRNAs in PCa.

METHODS

mRNA data and clinical information of PCa were achieved from TCGA database, and ARGs were obtained from the HADb. AR-lncRNAs were identified by correlation analysis of DE ARGs and lncRNAs. Univariate Cox regression, LASSO regression, and multivariate Cox regression were used to identify the prognostic AR-lncRNA signature and constructed a risk model. GESA was used to biological function analysis between high- and low-risk score group. A nomogram was constructed and used to predicate the survival of PCa patients. A calibration curve was used to determines accuracy of the predication model. AR-related ceRNA network was constructed by correlation analysis. Expression of six AR-related lncRNAs were detected by qRT-PCR.

RESULTS

222 ARGs and 385 AR-lncRNAs were screened from PCa and normal tissues, and 17 AR-lncRNAs were identified as prognostic signature for PCa. Based on the expression of prognostic signature, a risk score was calculated, and PCa samples were distributed into high- and low-risk score groups. The biological function and predicated value of the prognostic signature were also examined. Finally, based on the correlation between each ARG and its prognostic signature, three modules of AR-lncRNA-miRNA-mRNA regulatory networks were constructed based on 6 AR-lncRNAs, 17 miRNAs, and 12 ARGs. And we found that AC012085.2, UBXN10-AS1, LINC00261 downregulated, whereas AP004608.1, AC104667.2, AC008610.1 upregulated in PCa compared with BPH tissues.

CONCLUSION

Our finding supplied the potential AR-lncRNAs prognostic signature for PCa.

The role of fructose 1,6-bisphosphate-mediated glycolysis/gluconeogenesis genes in cancer prognosis

Metabolic reprogramming and elevated glycolysis levels are associated with tumor progression. However, despite cancer cells selectively inhibiting or expressing certain metabolic enzymes, it is unclear whether differences in gene profiles influence patient outcomes. Therefore, identifying the differences in enzyme action may facilitate discovery of gene ontology variations to characterize tumors. Fructose-1,6-bisphosphate (F-1,6-BP) is an important intermediate in glucose metabolism, particularly in cancer. Gluconeogenesis and glycolysis require fructose-1,6-bisphosphonates 1 (FBP1) and fructose-bisphosphate aldolase A (ALDOA), which participate in F-1,6-BP conversion. Increased expression of ALDOA and decreased expression of FBP1 are associated with the progression of various forms of cancer in humans. However, the exact molecular mechanism by which ALDOA and FBP1 are involved in the switching of F-1,6-BP is not yet known. As a result of their pancancer pattern, the relationship between ALDOA and FBP1 in patient prognosis is reversed, particularly in lung adenocarcinoma (LUAD) and liver hepatocellular carcinoma (LIHC). Using The Cancer Genome Atlas (TCGA), we observed that FBP1 expression was low in patients with LUAD and LIHC tumors, which was distinct from ALDOA. A similar trend was observed in the analysis of Cancer Cell Line Encyclopedia (CCLE) datasets. By dissecting downstream networks and possible upstream regulators, using ALDOA and FBP1 as the core, we identified common signatures and interaction events regulated by ALDOA and FBP1. Notably, the identified effectors dominated by ALDOA or FBP1 were distributed in opposite patterns and can be considered independent prognostic indicators for patients with LUAD and LIHC. Therefore, uncovering the effectors between ALDOA and FBP1 will lead to novel therapeutic strategies for cancer patients.

Targeting autophagy in prostate cancer: preclinical and clinical evidence for therapeutic response

Prostate cancer is a leading cause of death worldwide and new estimates revealed prostate cancer as the leading cause of death in men in 2021. Therefore, new strategies are pertinent in the treatment of this malignant disease. Macroautophagy/autophagy is a “self-degradation” mechanism capable of facilitating the turnover of long-lived and toxic macromolecules and organelles. Recently, attention has been drawn towards the role of autophagy in cancer and how its modulation provides effective cancer therapy. In the present review, we provide a mechanistic discussion of autophagy in prostate cancer. Autophagy can promote/inhibit proliferation and survival of prostate cancer cells. Besides, metastasis of prostate cancer cells is affected (via induction and inhibition) by autophagy. Autophagy can affect the response of prostate cancer cells to therapy such as chemotherapy and radiotherapy, given the close association between autophagy and apoptosis. Increasing evidence has demonstrated that upstream mediators such as AMPK, non-coding RNAs, KLF5, MTOR and others regulate autophagy in prostate cancer. Anti-tumor compounds, for instance phytochemicals, dually inhibit or induce autophagy in prostate cancer therapy. For improving prostate cancer therapy, nanotherapeutics such as chitosan nanoparticles have been developed. With respect to the context-dependent role of autophagy in prostate cancer, genetic tools such as siRNA and CRISPR-Cas9 can be utilized for targeting autophagic genes. Finally, these findings can be translated into preclinical and clinical studies to improve survival and prognosis of prostate cancer patients.

• Prostate cancer is among the leading causes of death in men where targeting autophagy is of importance in treatment;

• Autophagy governs proliferation and metastasis capacity of prostate cancer cells;

• Autophagy modulation is of interest in improving the therapeutic response of prostate cancer cells;

• Molecular pathways, especially involving non-coding RNAs, regulate autophagy in prostate cancer;

• Autophagy possesses both diagnostic and prognostic roles in prostate cancer, with promises for clinical application.

A Ferroptosis-Related Gene Prognostic Index Associated With Biochemical Recurrence and Radiation Resistance for Patients With Prostate Cancer Undergoing Radical Radiotherapy

Background: Ferroptosis is a new type of programmed cell death which has been reported to be involved in the development of various cancers. In this study, we attempted to explore the possible links between ferroptosis and prostate cancer (PCa), and a novel ferroptosis-related gene prognostic index (FGPI) was constructed to predict biochemical recurrence (BCR) and radiation resistance for PCa patients undergoing radical radiotherapy (RRT). Moreover, the tumor immune microenvironment (TME) of PCa was analyzed.

Methods: We merged four GEO datasets by removing batch effects. All analyses were conducted with R version 3.6.3 and its suitable packages. Cytoscape 3.8.2 was used to establish a network of transcriptional factor and competing endogenous RNA.

Results: We established the FGPI based on ACSL3 and EPAS1. We observed that FGPI was an independent risk factor of BCR for PCa patients (HR: 3.03; 95% CI: 1.68–5.48), consistent with the result of internal validation (HR: 3.44; 95% CI: 1.68–7.05). Furthermore, FGPI showed high ability to identify radiation resistance (AUC: 0.963; 95% CI: 0.882–1.00). LncRNA PART1 was significantly associated with BCR and might modulate the mRNA expression of EPAS1 and ACSL3 through interactions with 60 miRNAs. Gene set enrichment analysis indicated that FGPI was enriched in epithelial–mesenchymal transition, allograft rejection, TGF beta signaling pathway, and ECM receptor interaction. Immune checkpoint and m6A analyses showed that PD-L2, CD96, and METTL14 were differentially expressed between BCR and no BCR groups, among which CD96 was significantly associated with BCR-free survival (HR: 1.79; 95% CI: 1.06–3.03). We observed that cancer-related fibroblasts (CAFs), macrophages, stromal score, immune score, estimate score, and tumor purity were differentially expressed between BCR and no BCR groups and closely related to BCR-free survival (HRs were 2.17, 1.79, 2.20, 1.93, 1.92, and 0.52 for cancer-related fibroblasts, macrophages, stromal score, immune score, estimate score, and tumor purity, respectively). Moreover, cancer-related fibroblasts (coefficient: 0.20), stromal score (coefficient: 0.14), immune score (coefficient: 0.14), estimate score (coefficient: 0.15), and tumor purity (coefficient: −0.15) were significantly related to FGPI, among which higher positive correlation between cancer-related fibroblasts and FGPI was observed.

Conclusion: We found that FGPI based on ACSL3 and EPAS1 might be used to predict BCR and radiation resistance for PCa patients. CD96 and PD-L2 might be a possible target for drug action. Besides, we highlighted the importance of immune evasion in the process of BCR.

Small activating RNA-activated NIS gene promotes 131I uptake and inhibits thyroid cancer via AMPK/mTOR pathway

BACKGROUND

Sodium/iodide symporter (NIS) acts as a vital role in regulation of iodide uptake in thyroid cancer. However, the efficient approach to increase NIS expression and the mechanism of NIS-mediated iodide uptake in thyroid cancer remain unclear.

METHODS

Small activating RNA (saRNA) was used to promote NIS expression. And the cell viability, apoptosis, and autophagy were detected using Cell count-kit 8 (CCK-8), Annexin V-FITC/PI double staining, and GFP-LC3 immunofluorescence assays, respectively. The protein levels of caspase 3, Bax, Bcl-2, ATG5, ATG12, LC3B Ⅱ to LC3B Ⅰ, Beclin 1, P62, AMPK, mTOR, P70S6K, actin, and phosphorylation of AMPK, mTOR, P70S6K were determined by western blotting. Moreover, a nude murine node with transplanted NC-dsRNA or NIS-482-transfected SW579 cells was used to examine the effect of NIS-mediated autophagy in vivo. And the levels of caspase 3 and ki67 were examined by immunohistochemical staining assay.

RESULTS

saRNA mediated NIS mRNA and protein upregulated in SW579 cells. saRNA-mediated NIS expression inhibited cell proliferation, induced apoptosis and autophagy, and promoted iodide uptake in SW579 cells. Moreover, the effects of NIS on cells were enhanced by autophagy activator Rapamycin whereas reversed by autophagy inhibitor 3-Methyladenine (3-MA). For mechanism analysis, we found that NIS upregulation exerted the effects on cell proliferation, apoptosis, autophagy, and iodide uptake via regulating AMPK/mTOR pathway. We also demonstrated that saRNA-mediated NIS expression promoted iodide uptake in vivo.

CONCLUSION

saRNA-mediated NIS expression acted as a critical role in increasing iodide uptake via AMPK/mTOR pathway in thyroid cancer.

FBP1 enhances the radiosensitivity by suppressing glycolysis via the FBXW7/mTOR axis in nasopharyngeal carcinoma cells

AIMS

The high glycolysis state of tumor cells is closely related to radioresistance. Fructose-1,6-bisphosphatase (FBP1) can regulate aerobic glycolysis and exerts tumor suppressor effects in many cancers, but its role in nasopharyngeal carcinoma (NPC) remains to be investigated.

MATERIALS AND METHODS

RT-qPCR was used to measure FBP1 mRNA level. Glucose consumption, lactic acid production and ATP level was determined to evaluate glycolysis. The sensitivity of NPC cells to radiation was analyzed by MTT assay. Apoptosis was performed using flow cytometry. Gain- and loss-of function assays were carried out to explore the specific role of FBP1 and FBXW7 (F-box and WD repeat domain-containing 7) in NPC cell functions. The interactions between FBXW7 and FBP1 or mTOR were validated with co-immunoprecipitation assay. The in vivo experiments with xenografts were used to evaluate the role of FBP1 in tumor growth.

KEY FINDINGS

FBP1 expression was lower in NPC tissues and cells than in normal controls and nasopharyngeal epithelial cells. Human recombinant FBP1 (rh-FBP1) treatment suppressed glycolysis in NPC cells. Besides, silencing FBP1 weakened the radiosensitivity and alleviated radiation-induced apoptosis and DNA damage by promoting glycolysis. Mechanism exploration found that FBP1 promoted FBXW7 protein level through suppressing the autoubiquitination of FBXW7. Then, FBXW7 restrained mTOR level by facilitating mTOR ubiquitination, thereby suppressing glycolysis and promoting radiation-induced apoptosis and DNA damage. Furthermore, overexpressing FBP1 in vivo hindered tumor growth and enhanced the antitumor activity of radiation.

SIGNIFICANCE

FBP1 promoted the radiosensitivity in NPC cells by inhibiting glycolysis through the FBXW7/mTOR axis.