Dual functions of autophagy in the response of breast tumor cells to radiation: cytoprotective autophagy with radiation alone and cytotoxic autophagy in radiosensitization by vitamin D 3

Blocking ACSL6 Compromises Autophagy via FLI1-Mediated Downregulation of COLs to Radiosensitize Lung Cancer

Lung cancer (LC) is the leading cause of cancer-related mortality worldwide. Radiotherapy is the main component of LC treatment; however, its efficacy is often limited by radioresistance development, resulting in unsatisfactory clinical outcomes. Here, we found that LC radiosensitivity is up-regulated by decreased expression of long-chain acyl-CoA synthase 6 (ACSL6) after irradiation. Deletion of ACSL6 results in significant elevation of Friend leukemia integration 1 transcription factor (FLI1) and a marked decline of collagens (COLs). Blocking of ACSL6 impairs the tumor growth and upregulates FLI1, which reduces the levels of COLs and compromises irradiation-induced autophagy, leading to considerable therapeutic benefits during radiotherapy. Moreover, the direct interaction between ACSL6 and FLI1 and engagement between FLI1 and COLs indicates the involvement of the ACSL6-FLI1-COL axis. Finally, the potently adjusted autophagy flux reduces its otherwise contributive capability in surviving irradiation stress and leads to satisfactory radiosensitization for LC radiotherapy. These results demonstrate that enhanced ACSL6 expression promotes the aggressive performance of irradiated LC through increased FLI1-COL-mediated autophagy flux. Thus, the ACSL6-FLI1-Col-autophagy axis may be targeted to enhance the radiosensitivity of LC and improve the management of LC in radiotherapy.

Advances in the molecular regulation mechanism of tumor dormancy and its therapeutic strategy

Tumor dormancy is a stage in the growth and development of malignant cells and is one of the biological characteristics of malignant cells. Complex transitions involving dormant tumor cells between quiescent and proliferative states pose challenges for tumor eradication. This paper explores the biological features and molecular mechanisms of tumor dormancy and highlights emerging therapies. The strategies discussed promise innovative clinical potential against malignant tumors. Understanding the mechanisms of dormancy can help provide valuable insights into the diagnosis and treatment of malignant tumors to advance the fight against this world problem.

1,25D/VDR inhibits pancreatic β cell ferroptosis by downregulating FOXO1 expression in diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a global health problem that seriously threatens human health. Vitamin D (VD) has antidiabetic effects. However, the protective mechanism of 1,25-dihydroxyvitamin D3 (1,25D) on T2DM is still unclear.

METHODS

A rat model of T2DM was constructed using a high-fat diet combined with intraperitoneal injection of streptozotocin (STZ). Glucose tolerance was assessed by an oral glucose tolerance test (OGTT). Insulin secretion in blood and cell supernatant was determined by ELISA. Cell viability was analysed by CCK-8 assay. The level of ROS was detected by the DCFH-DA fluorescent probe method. The iron level in pancreatic tissues and cells was detected by an iron assay kit. Immunofluorescence staining was used to detect the expression of the pancreatic β cell marker CD49a. Furthermore, the protein expression levels of ferroptosis pathway-related proteins and vitamin D receptor (VDR) were detected by western blot. Downstream VDR targets were screened by proteomic sequencing.

RESULTS

The DM group had increased glucose levels and decreased insulin secretion, while 1,25D treatment decreased glucose levels and increased insulin secretion. 1,25D also suppressed DM-induced ferroptosis in pancreatic tissues in vivo. In addition, 1,25D significantly enhanced the viability of pancreatic β cells and reduced the levels of ROS and iron. 1,25D significantly upregulated the expression of VDR and the ferroptosis-related pathway protein GPX4 and downregulated the expression of ACSL4. Furthermore, knockdown of VDR reversed the effects of 1,25D on cell viability, ROS and iron levels, and ferroptosis-related protein expression in pancreatic β cells. Proteomic sequencing revealed that FOXO1 was the downstream target gene of VDR. Knockdown of FOXO1 reduced pancreatic β cell death, decreased ROS, iron and ACSL4 levels, and increased GPX4 levels.

CONCLUSION

1,25D/VDR inhibited pancreatic β cell ferroptosis in T2DM by downregulating the expression of FOXO1. This study provides a new theoretical basis for basic research on T2DM and is expected to establish a new idea for the treatment of T2DM.

Towards dual function of autophagy in breast cancer: A potent regulator of tumor progression and therapy response

As a devastating disease, breast cancer has been responsible for decrease in life expectancy of females and its morbidity and mortality are high. Breast cancer is the most common tumor in females and its treatment has been based on employment of surgical resection, chemotherapy and radiotherapy. The changes in biological behavior of breast tumor relies on genomic and epigenetic mutations and depletions as well as dysregulation of molecular mechanisms that autophagy is among them. Autophagy function can be oncogenic in increasing tumorigenesis, and when it has pro-death function, it causes reduction in viability of tumor cells. The carcinogenic function of autophagy in breast tumor is an impediment towards effective therapy of patients, as it can cause drug resistance and radio-resistance. The important hallmarks of breast tumor such as glucose metabolism, proliferation, apoptosis and metastasis can be regulated by autophagy. Oncogenic autophagy can inhibit apoptosis, while it promotes stemness of breast tumor. Moreover, autophagy demonstrates interaction with tumor microenvironment components such as macrophages and its level can be regulated by anti-tumor compounds in breast tumor therapy. The reasons of considering autophagy in breast cancer therapy is its pleiotropic function, dual role (pro-survival and pro-death) and crosstalk with important molecular mechanisms such as apoptosis. Moreover, current review provides a pre-clinical and clinical evaluation of autophagy in breast tumor.

MED16 Promotes Tumour Progression and Tamoxifen Sensitivity by Modulating Autophagy through the mTOR Signalling Pathway in ER-Positive Breast Cancer

Recent studies have shown that the mediator complex (MED) plays a vital role in tumorigenesis and development, but the role of MED16 (mediator complex subunit 16) in breast cancer (BC) is not clear. Increasing evidence has shown that the mTOR pathway is important for tumour progression and therapy. In this study, we demonstrated that the mTOR signalling pathway is regulated by the expression level of MED16 in ER+ breast cancer. With the analysis of bioinformatics data and clinical specimens, we revealed an elevated expression of MED16 in luminal subtype tumours. We found that MED16 knockdown significantly inhibited cell proliferation and promoted G1 phase cell cycle arrest in ER+ BC cell lines. Downregulation of MED16 markedly reduced the sensitivity of ER+ BC cells to tamoxifen and increased the stemness and autophagy of ER+ BC cells. Bioinformatic analysis of similar genes to MED16 were mainly enriched in autophagy, endocrine therapy and mTOR signalling pathways, and the inhibition of mTOR-mediated autophagy restored sensitivity to tamoxifen by MED16 downregulation in ER+ BC cells. These results suggest an important role of MED16 in the regulation of tamoxifen sensitivity in ER+ BC cells, crosstalk between the mTOR signalling pathway-induced autophagy, and together, with the exploration of tamoxifen resistance, may indicate a new therapy option for endocrine therapy-resistant patients.

The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies?

Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.

Quercus acutissima Carruth. root extract triggers apoptosis, autophagy and inhibits cell viability in breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

The bark of Quercus acutissima Carruth. (QA) has long been used by Chinese people to treat noncancerous growths and cancerous ailments. It was traditionally used by Chinese folk to inhibit tumor proliferation in cancerous treatment, but the specific mechanism remain to be elucidated.

AIM OF THE STUDY

This study investigated the anticancer activities of QA root extract and its regulatory pathways in two human breast cancer cell lines (MCF-7 and SUM159).

MATERIALS AND METHODS

Dried QA root barks were extracted by ethanol and used to treat human breast cancer MCF-7 and SUM159 cells with varying concentrations. The CCK-8 assay, Hoechst 33342 staining assay and wound healing assay were used to detect the cell proliferation, apoptotic cell morphology, and cell migration in each group, respectively. Caspase 3 activity assay kit was used to determine caspase 3 activity. Western blot was used to measure proteins expression level in apoptosis and autophagy pathways (Bcl-W, caspase 3, Beclin1, LC3 and Atg5). LC-MS was performed to determine the chemical components in QA root extract.

RESULTS

CCK-8 assay showed that QA root extract significantly inhibited cell viability and proliferation in breast cancer cells by a concentration-dependent manner. Cell wound healing assay indicated that it had high suppression ability on cell migration both in MCF-7 and SUM159 cells. QA root extract treatment induced the morphological and nuclear structural changes in breast cancer cells including rounded appearance and shrunken nucleus with several nuclear body fragments. Western blot indicated that QA root extract induced mitochondria-mediated apoptosis by up-regulating caspase 3 and down-regulating Bcl-W. Moreover, QA root extract up-regulated Beclin1 and Atg5, and activated LC3 in two human breast cancer cell lines. LC-MS results showed that QA root extract contains high content of bioactive compounds like coumarins and derivatives, prenol lipids, flavonoids and tannins.

CONCLUSIONS

QA root extract inhibited cell proliferation and migration in MCF-7 and SUM159 cells, and it also induced cell morphology changes and regulated mitochondria-mediated apoptotic cell death and autophagic cell death.

Advances in the Study of CircRNAs in Tumor Drug Resistance

Recent studies have revealed that circRNAs can affect tumor DNA damage and repair, apoptosis, proliferation, and invasion and influence the transport of intratumor substances by acting as miRNA sponges and transcriptional regulators and binding to proteins in a variety of ways. However, research on the role of circRNAs in cancer radiotherapy and chemoresistance is still in its early stages. Chemotherapy is a common approach to oncology treatment, but the development of tumor resistance limits the overall clinical efficacy of chemotherapy for cancer patients. The current study suggests that circRNAs have a facilitative or inhibitory effect on the development of resistance to conventional chemotherapy in a variety of tumors, suggesting that circRNAs may serve as a new direction for the study of antitumor drug resistance. In this review, we will briefly discuss the biological features of circRNAs and summarize the recent progression of the involvement of circRNAs in the development and pathogenesis of cancer chemoresistance.

Vitamin D and Cancer: An Historical Overview of the Epidemiology and Mechanisms

This is a narrative review of the evidence supporting vitamin D's anticancer actions. The first section reviews the findings from ecological studies of cancer with respect to indices of solar radiation, which found a reduced risk of incidence and mortality for approximately 23 types of cancer. Meta-analyses of observational studies reported the inverse correlations of serum 25-hydroxyvitamin D [25(OH)D] with the incidence of 12 types of cancer. Case-control studies with a 25(OH)D concentration measured near the time of cancer diagnosis are stronger than nested case-control and cohort studies as long follow-up times reduce the correlations due to changes in 25(OH)D with time. There is no evidence that undiagnosed cancer reduces 25(OH)D concentrations unless the cancer is at a very advanced stage. Meta-analyses of cancer incidence with respect to dietary intake have had limited success due to the low amount of vitamin D in most diets. An analysis of 25(OH)D-cancer incidence rates suggests that achieving 80 ng/mL vs. 10 ng/mL would reduce cancer incidence rates by 70 ± 10%. Clinical trials have provided limited support for the UVB-vitamin D-cancer hypothesis due to poor design and execution. In recent decades, many experimental studies in cultured cells and animal models have described a wide range of anticancer effects of vitamin D compounds. This paper will review studies showing the inhibition of tumor cell proliferation, dedifferentiation, and invasion together with the sensitization to proapoptotic agents. Moreover, 1,25-(OH)2D3 and other vitamin D receptor agonists modulate the biology of several types of stromal cells such as fibroblasts, endothelial and immune cells in a way that interferes the apparition of metastases. In sum, the available mechanistic data support the global protective action of vitamin D against several important types of cancer.

Responsive nanomedicines enhanced by or enhancing physical modalities to treat solid cancer tumors: Preclinical and clinical evidence of safety and efficacy

Nanomedicine has improved cancer treatment but not to the extent anticipated. Responsive nanomedicines enhanced by physical modalities (radiation, ultrasounds, alternating magnetic fields) or enhancing the activity of physical modalities such as radiotherapy to kill cancer represents an important approach in improving the safety and anticancer effectiveness. Importantly, the combined treatments have shown promise for the treatment of difficult to treat tumors, such as tumors that are resistant to chemotherapy (multi drug resistant, MDR) or radiotherapy and hypoxic tumors, and for the prevention of tumor metastasis. In this review, the mechanisms of responsive nanomedicines activity enhancement by physical means and vice versa are presented and preclinical and, most importantly, clinical evidence of the safety and efficacy of nanomedicines enhanced by or enhancing by physical modalities in treating solid tumors are critically discussed.

Vitamin D and Breast Cancer: Mechanistic Update

The presence of the vitamin D receptor (VDR) in mammary gland and breast cancer has long been recognized, and multiple preclinical studies have demonstrated that its ligand, 1,25-dihydroxyvitamin D (1,25D), modulates normal mammary gland development and inhibits growth of breast tumors in animal models. Vitamin D deficiency is common in breast cancer patients, and some evidence suggests that low vitamin D status enhances the risk for disease development or progression. Although many 1,25D-responsive targets in normal mammary cells and in breast cancers have been identified, validation of specific targets that regulate cell cycle, apoptosis, autophagy, and differentiation, particularly in vivo, has been challenging. Model systems of carcinogenesis have provided evidence that both VDR expression and 1,25D actions change with transformation, but clinical data regarding vitamin D responsiveness of established tumors is limited and inconclusive. Because breast cancer is heterogeneous, the relevant VDR targets and potential sensitivity to vitamin D repletion or supplementation will likely differ between patient populations. Detailed analysis of VDR actions in specific molecular subtypes of the disease will be necessary to clarify the conflicting data. Genomic, proteomic, and metabolomic analyses of in vitro and in vivo model systems are also warranted to comprehensively understand the network of vitamin D-regulated pathways in the context of breast cancer heterogeneity. This review provides an update on recent studies spanning the spectrum of mechanistic (cell/molecular), preclinical (animal models), and translational work on the role of vitamin D in breast cancer. © 2021 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Combinations of Calcitriol with Anticancer Treatments for Breast Cancer: An Update

Preclinical, clinical, and epidemiological studies indicate that vitamin D3 (VD) deficiency is a risk factor for the development of breast cancer. Underlying mechanisms include the ability of calcitriol to induce cell differentiation, inhibit oncogenes expression, and modify different signaling pathways involved in the control of cell proliferation. In addition, calcitriol combined with different kinds of antineoplastic drugs has been demonstrated to enhance their beneficial effects in an additive or synergistic fashion. However, a recognized adjuvant regimen based on calcitriol for treating patients with breast cancer has not yet been fully established. Accordingly, in the present work, we review and discuss the preclinical and clinical studies about the combination of calcitriol with different oncological drugs, aiming to emphasize its main therapeutic benefits and opportunities for the treatment of this pathology.

The anticancer activity of root extract from Quercus acutissima Carruth. Via regulating apoptosis and autophagy in breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

The bark of Quercus acutissima Carruth. (QA) has long been used by Chinese people to treat noncancerous growths and cancerous ailments. It was traditionally used by Chinese folk to inhibit tumor proliferation in cancerous treatment, but the specific mechanism remain to be elucidated.

AIM OF THE STUDY

Breast cancer is the most common form of cancer in women and the leading cause of mortality around the globe. This study investigated the anticancer activities of QA root extract and its regulatory pathways in two human breast cancer cell lines (MCF-7 and SUM159).

MATERIALS AND METHODS

Dried QA root barks were extracted by ethanol and used to treat human breast cancer MCF-7 and SUM159 cells with varying concentrations. The CCK-8 assay, Hoechst 33342 staining assay and wound healing assay were used to detect the cell proliferation, apoptotic cell morphology, and cell migration in each group, respectively. Caspase 3 activity assay kit was used to determine caspase 3 activity. Western blot was used to measure proteins expression level in apoptosis and autophagy pathways (Bcl-W, caspase 3, Beclin1, LC3 and Atg5).

RESULTS

CCK-8 assay showed that QA root extract significantly inhibited cell viability and proliferation in breast cancer cells by a hormone receptor independent manner. Cell wound healing assay indicated that it had high suppression ability on cell migration both in MCF-7 and SUM159 cells. QA root extract treatment induced the morphological and nuclear structural changes in breast cancer cells including rounded appearance and shrunken nucleus with several nuclear body fragments. Western blot indicated that QA root extract induced mitochondria-mediated apoptosis by up-regulating caspase 3 and down-regulating Bcl-W. Moreover, QA root extract up-regulated Beclin1 and Atg5, and activated LC3 in two human breast cancer cell lines.

CONCLUSIONS

QA root extract inhibited cell proliferation and migration in MCF-7 and SUM159 cells, and it also induced cell morphology changes and regulated mitochondria-mediated apoptotic cell death and autophagic cell death.

Vitamin D Enhances Radiosensitivity of Colorectal Cancer by Reversing Epithelial-Mesenchymal Transition

Colorectal cancer (CRC) is often resistant to conventional therapies. Previous studies have reported the anticancer effects of vitamin D in several cancers, its role in radiotherapy (RT) remains unknown. We found that 1α, 25-dihydroxyvitamin D₃ (VD₃), the biologically active form of vitamin D, had antitumor effect on CRC and sensitized CRC cells to ionizing radiation (IR). VD₃ demonstrated synergistic effect in combination with IR, which were detected by colony formation and cell proliferation assay. Radiosensitivity restoration induced by VD₃ was associated with a series of phenotypes, including apoptosis, autophagy, and epithelial-mesenchymal transition (EMT). Using proteomics, “regulation of cell migration” and “cadherin” were found to be obviously enriched GO terms. Moreover, cystatin D and plasminogen activator inhibitor-1 (PAI-1), the differentially expressed proteins, were associated with EMT. Next, we confirmed the contributions of these two genes in enhancing IR sensitivity of CRC cells upon inhibition of EMT. As determined by proteomics, the mechanism underlying such sensitivity involved partially block of JAK/STAT3 signaling pathway. Furthermore, VD₃ also elicited sensitization to RT in xenograft CRC models without additional toxicity. Our study revealed that VD₃ was able to act in synergy with IR both in vitro and in vivo and could also confer radiosensitivity by regulating EMT, thereby providing a novel insight for elevating the efficacy of therapeutic regimens.

Vitamin D in autophagy signaling for health and diseases: Insights on potential mechanisms and future perspectives

Vitamin D regulates the pleiotropic effect to maintain cellular homeostasis and epidemiological evidence establishes an association between vitamin D deficiency and various human diseases. Here, the role of autophagy, the cellular self-degradation process, in vitamin D-dependent function is documented in different cellular settings and discussed the molecular aspects for treating chronic inflammatory, infectious diseases, and cancer. Vitamin D activates autophagy through a genomic and non-genomic signaling pathway to influence a wide variety of physiological functions of different body organs along with bone health and calcium metabolism. Moreover, it induces autophagy as a protective mechanism to inhibit oxidative stress and apoptosis to regulate cell proliferation, differentiation, and immune modulation. Furthermore, vitamin D and its receptor regulate autophagy signaling to control inflammation and host immunity by activating antimicrobial defense mechanisms. Vitamin D has been revealed as a potent anticancer agent and induces autophagy to increase the response to radiation and chemotherapeutic drugs for potential cancer therapy. Increasing vitamin D levels in the human body through timely exposure to sunlight or vitamin D supplements could activate autophagy as part of the homeostasis mechanism to prevent multiple human diseases and aging-associated dysfunctions.

Vitamin D3/phospholipid complex decorated caseinate nanomicelles for targeted delivery of synergistic combination therapy in breast cancer

Targeted delivery of cytotoxic drugs has shown great potential in cancer therapy. In this light, vitamin D3 (vit.D3)-coated micelles were fabricated to encapsulate the cytotoxic drug; etoposide (ETP). Sodium caseinate micelles were first utilized to encapsulate vit.D3 and ETP within their hydrophobic core, then drug-loaded micelles were further decorated with an envelope of vit.D3/ phospholipid complex to enhance the active targeting potency of fabricated micelles via exploiting vit.D3 receptors (VDRs) overexpressed on the outer surface of breast cancer cells. In vitro cytotoxicity studies showed that fabricated micelles exhibited improved anticancer effect on MDA MB-231 and MCF-7 human breast cancer cell lines in comparison to free vit.D3 + ETP without any significant toxicity on normal human lung fibroblast (Wi-38) cells. In vivo biodistribution and efficacy studies in Ehrlich ascites tumor animal model revealed that fabricated micelles manifested improved accumulation in tumor tissue due to active targeting potential of vit.D3 without any remarkable toxicity. More importantly, fabricated micelles resulted in enhanced tumor apoptosis, reduced angiogenesis, invasion and autophagy, besides a decline in the tumor expression levels of both miR-21 and miR-192. Therefore, vit.D3/ETP micelles could serve as a favorable actively targeted anticancer delivery system having a superior effect over the free combination.

Effect of 1α,25-Dihydroxyvitamin D3 on the Radiation Response in Prostate Cancer: Association With IL-6 Signaling

Radiotherapy (RT) is the main treatment modality for prostate cancer (PCa). This study investigated the role of IL-6 in biological sequelae following irradiation and highlighted the effects of 1α,25-dihydroxyvitamin D3 (calcitriol) on the radiation response of PCa and its relationship with IL-6 signaling. Human and murine PCa cell lines were used to examine the response to irradiation in vitro and in vivo. The relationship of IL-6 expression with clinicopathologic characteristics in 104 PCa patients treated with definite RT was also examined. We also investigated the changes in radiation response after calcitriol supplementation and the relationship between calcitriol and IL-6 signaling by conducting cellular and animal experiments. Based on clinical samples, the positivity of IL-6 staining is a significant predictor of biochemical failure-free survival for PCa patients treated with definite RT. Data from preclinical models showed that inhibition of IL-6 increased the response of PCa to radiation, which was associated with increased oxidative DNA damage, attenuated EMT and MDSC recruitment, and decreased tumor regrowth. Moreover, increased vitamin D₃ levels by calcitriol supplementation or induction by UVB-radiation was associated with inhibited IL-6 signaling and increased the response to irradiation observed in animal models. These data demonstrate that IL-6 play a critical role in the radiation response of PCa, which involved tumor cell killing and altering the tumor microenvironment. Directly targeting IL-6 signaling or vitamin D₃ supplement with oral or light treatment could be a promising strategy to increase the response of PCa to radiation.

Inhibition of Antiestrogen-Promoted Pro-Survival Autophagy and Tamoxifen Resistance in Breast Cancer through Vitamin D Receptor

We determined how vitamin D receptor (VDR) is linked to disease outcome in estrogen receptor-positive (ER+) breast cancer patients treated with tamoxifen (TAM). Breast cancer patients (n = 581) in four different datasets were divided into those expressing higher (above median) and lower levels of VDR in pretreatment ER+ tumors. Across all datasets, TAM-treated patients with higher pretreatment tumor VDR expression exhibited significantly longer recurrence-free survival. Ingenuity pathway analysis identified autophagy and unfolded protein response (UPR) as top differentially expressed pathways between high and low VDR-expressing ER+ cancers. Activation of VDR with vitamin D (VitD), either calcitriol or its synthetic analog EB1089, sensitized MCF-7-derived, antiestrogen-resistant LCC9 human breast cancer cells to TAM, and attenuated increased UPR and pro-survival autophagy. Silencing of VDR blocked these effects through the IRE1α-JNK pathway. Further, silencing of VDR impaired sensitivity to TAM in antiestrogen-responsive LCC1 cells, and prevented the effects of calcitriol and EB1089 on UPR and autophagy. In a preclinical mouse model, dietary VitD supplementation induced VDR activation and reduced carcinogen-induced ER+ mammary tumor incidence. In addition, IRE1α-JNK signaling was downregulated and survival autophagy was inhibited in mammary tumors of VitD-supplemented mice. Thus, activation of VDR is predictive of reduced risk of breast cancer recurrence in ER+ patients, possibly by inhibiting antiestrogen-promoted pro-survival autophagy.

Resveratrol as an Adjuvant for Normal Tissues Protection and Tumor Sensitization

Cancer is one of the most complicated diseases in present-day medical science. Yearly, several studies suggest various strategies for preventing carcinogenesis. Furthermore, experiments for the treatment of cancer with low side effects are ongoing. Chemotherapy, targeted therapy, radiotherapy and immunotherapy are the most common non-invasive strategies for cancer treatment. One of the most challenging issues encountered with these modalities is low effectiveness, as well as normal tissue toxicity for chemo-radiation therapy. The use of some agents as adjuvants has been suggested to improve tumor responses and also alleviate normal tissue toxicity. Resveratrol, a natural flavonoid, has attracted a lot of attention for the management of both tumor and normal tissue responses to various modalities of cancer therapy. As an antioxidant and anti-inflammatory agent, in vitro and in vivo studies show that it is able to mitigate chemo-radiation toxicity in normal tissues. However, clinical studies to confirm the usage of resveratrol as a chemo-radioprotector are lacking. In addition, it can sensitize various types of cancer cells to both chemotherapy drugs and radiation. In recent years, some clinical studies suggested that resveratrol may have an effect on inducing cancer cell killing. Yet, clinical translation of resveratrol has not yielded desirable results for the combination of resveratrol with radiotherapy, targeted therapy or immunotherapy. In this paper, we review the potential role of resveratrol for preserving normal tissues and sensitization of cancer cells in combination with different cancer treatment modalities.

Ferroptosis, radiotherapy, and combination therapeutic strategies

Ferroptosis, an iron-dependent form of regulated cell death driven by peroxidative damages of polyunsaturated-fatty-acid-containing phospholipids in cellular membranes, has recently been revealed to play an important role in radiotherapy-induced cell death and tumor suppression, and to mediate the synergy between radiotherapy and immunotherapy. In this review, we summarize known as well as putative mechanisms underlying the crosstalk between radiotherapy and ferroptosis, discuss the interactions between ferroptosis and other forms of regulated cell death induced by radiotherapy, and explore combination therapeutic strategies targeting ferroptosis in radiotherapy and immunotherapy. This review will provide important frameworks for future investigations of ferroptosis in cancer therapy.

Immune Response: A Missed Opportunity Between Vitamin D and Radiotherapy

Radiotherapy (RT) is a mainstay treatment in several types of cancer and acts by mediating various forms of cancer cell death, although it is still a large challenge to enhance therapy efficacy. Radiation resistance represents the main cause of cancer progression, therefore, overcoming treatment resistance is now the greatest challenge for clinicians. Increasing evidence indicates that immune response plays a role in reprogramming the radiation-induced tumor microenvironment (TME). Intriguingly, radiation-induced immunosuppression possibly overwhelms the ability of immune system to ablate tumor cells. This induces an immune equilibrium, which, we hypothesize, is an opportunity for radiosensitizers to make actions. Vitamin D has been reported to act in synergistic with RT by potentiating antiproliferative effect induced by therapeutics. Additionally, vitamin D can also regulate the TME and may even lead to immunostimulation by blocking immunosuppression following radiation. Previous reviews have focused on vitamin D metabolism and epidemiological trials, however, the synergistic effect of vitamin D and existing therapies remains unknown. This review summarizes vitamin D mediated radiosensitization, radiation immunity, and vitamin D-regulated TME, which may contribute to more successful vitamin D-adjuvant radiotherapy.

Is targeting autophagy mechanism in cancer a good approach? The possible double-edge sword effect

Autophagy is a conserved cellular process required to maintain homeostasis. The hallmark of autophagy is the formation of a phagophore that engulfs cytosolic materials for degradation and recycling to synthesize essential components. Basal autophagy is constitutively active under normal conditions and it could be further induced by physiological stimuli such as hypoxia, nutrient starvation, endoplasmic reticulum stress,energy depletion, hormonal stimulation and pharmacological treatment. In cancer, autophagy is highly context-specific depending on the cell type, tumour microenvironment, disease stage and external stimuli. Recently, the emerging role of autophagy as a double-edged sword in cancer has gained much attention. On one hand, autophagy suppresses malignant transformation by limiting the production of reactive oxygen species and DNA damage during tumour development. Subsequently, autophagy evolved to support the survival of cancer cells and promotes the tumourigenicity of cancer stem cells at established sites. Hence, autophagy is an attractive target for cancer therapeutics and researchers have been exploiting the use of autophagy modulators as adjuvant therapy. In this review, we present a summary of autophagy mechanism and controlling pathways, with emphasis on the dual-role of autophagy (double-edged sword) in cancer. This is followed by an overview of the autophagy modulation for cancer treatment and is concluded by a discussion on the current perspectives and future outlook of autophagy exploitation for precision medicine.

Isoquercitrin induces apoptosis and autophagy in hepatocellular carcinoma cells via AMPK/mTOR/p70S6K signaling pathway

Hepatocellular carcinoma (HCC) is an aggressive malignancy with high rates of metastasis and relapse. Isoquercitrin (ISO), a natural flavonoid present in the Chinese bayberry and other plant species, reportedly exerts notable inhibitory effects on tumor cell proliferation, though the mechanism is unknown. In the present study, we exposed HepG2 and Huh7 human liver cancer cells to ISO and examined the roles of autophagy and apoptosis in ISO-mediated cell death. We found that ISO exposure inhibited cell viability and colony growth, activated apoptotic pathway, and triggered dysregulated autophagy by activating the AMPK/mTOR/p70S6K pathway. Autophagy inhibition using 3-methyladenine (3-MA) or Atg5-targeted siRNA decreased the Bax/Bcl-2 ratio, caspase-3 activation, and PARP cleavage and protected cells against ISO-induced apoptosis. Moreover, autophagy inhibition reversed the upregulation of AMPK phosphorylation and downregulation of mTOR and p70S6K phosphorylation elicited by ISO. By contrast, application of a broad-spectrum caspase inhibitor failed to inhibit autophagy in ISO-treated cells. These data indicate that ISO simultaneously induced apoptosis and autophagy, and abnormal induction of autophagic flux contributed to ISO-triggered caspase-3-dependent apoptosis.

Induction of STK11-dependent cytoprotective autophagy in breast cancer cells upon honokiol treatment

Cancer cells hijack autophagy pathway to evade anti-cancer therapeutics. Many molecular signaling pathways associated with drug-resistance converge on autophagy induction. Honokiol (HNK), a natural phenolic compound purified from Magnolia grandiflora, has recently been shown to impede breast tumorigenesis and, in the present study, we investigated whether breast cancer cells evoke autophagy to modulate therapeutic efficacy and functional networks of HNK. Indeed, breast cancer cells exhibit increased autophagosomes-accumulation, MAP1LC3B-II/LC3B-II-conversion, expression of ATG proteins as well as elevated fusion of autophagosomes and lysosomes upon HNK treatment. Breast cancer cells treated with HNK demonstrate significant growth inhibition and apoptotic induction, and these biological processes are blunted by macroautophagy/autophagy. Consequently, inhibiting autophagosome formation, abrogating autophagosome-lysosome fusion or genetic-knockout of BECN1 and ATG7 effectively increase HNK-mediated apoptotic induction and growth inhibition. Next, we explored the functional impact of tumor suppressor STK11 in autophagy induction in HNK-treated cells. STK11-silencing abrogates LC3B-II-conversion, and blocks autophagosome/lysosome fusion and lysosomal activity as illustrated by LC3B-Rab7 co-staining and DQ-BSA assay. Our results exemplify the cytoprotective nature of autophagy invoked in HNK-treated breast cancer cells and put forth the notion that a combined strategy of autophagy inhibition with HNK would be more effective. Indeed, HNK and chloroquine (CQ) show synergistic inhibition of breast cancer cells and HNK-CQ combination treatment effectively inhibits breast tumorigenesis and metastatic progression. Tumor-dissociated cells from HNK-CQ treated tumors exhibit abrogated invasion and migration potential. Together, these results implicate that breast cancer cells undergo cytoprotective autophagy to circumvent HNK and a combined treatment with HNK and CQ can be a promising therapeutic strategy for breast cancer.

Calcitriol inhibits apoptosis via activation of autophagy in hyperosmotic stress stimulated corneal epithelial cells in vivo and in vitro

BACKGROUND

Previously, calcitriol has been demonstrated as a potential therapeutic agent for dry eye, whilst its role on corneal epithelium death remains unclear. This study aims to investigate the relationship between apoptosis and autophagy on dry eye related scenario, as well as the effect of calcitriol and its potential mechanism.

METHODS

In vitro, immortalized human corneal epithelial cells (iHCEC) were cultured in hyperosmotic medium with or without various concentrations of calcitriol and other reagents. In vivo, Wistar rats were applied with benzalkonium chloride to induce dry eye. Then rats were topically treated with calcitriol (10^-6 M) for 14 days. Autophagy flux (LC3B-II and SQSTM1/P62) was examined by western blotting or immunostaining. To test cell apoptosis, western blotting for cleaved caspase-3, Annexin V/PI double staining and TUNEL assay were used. CCK-8 assay was performed to detect the cell viability. Small interfering RNA was used to knock down the expression of vitamin D receptor in iHCECs.

RESULTS

Autophagy activation could protect iHCECs against HS induced apoptosis in vitro, and calcitriol was able to augment autophagy flux via VDR signaling, shown as the remarkably elevated expression of LC3B-II, as well as the declined p62 expression. In vivo results further supported the protective role of calcitriol on corneal epithelium apoptosis through promoting autophagy in dry eye rats.

CONCLUSION

The current study indicated that autophagy was an adaptive change of corneal epithelial cells in response to hyperosmotic stress and calcitriol could prevent cells from apoptosis via further activation of autophagy through VDR pathway.

Ionizing Radiation as a Source of Oxidative Stress-The Protective Role of Melatonin and Vitamin D

Ionizing radiation (IR) has found widespread application in modern medicine, including medical imaging and radiotherapy. As a result, both patients and healthcare professionals are exposed to various IR doses. To minimize the negative side effects of radiation associated with oxidative imbalance, antioxidant therapy has been considered. In this review, studies on the effects of melatonin and vitamin D on radiation-induced oxidative stress are discussed. According to the research data, both substances meet the conditions for use as agents that protect humans against IR-induced tissue damage. Numerous studies have confirmed that melatonin, a hydro- and lipophilic hormone with strong antioxidant properties, can potentially be used as a radioprotectant in humans. Less is known about the radioprotective effects of vitamin D, but the results to date have been promising. Deficiencies in melatonin and vitamin D are common in modern societies and may contribute to the severity of adverse side effects of medical IR exposure. Hence, supporting supplementation with both substances seems to be of first importance. Interestingly, both melatonin and vitamin D have been found to selectively radiosensitise cancer cells, which makes them promising adjuvants in radiotherapy. More research is needed in this area, especially in humans.

1α,25(OH)2D3 Radiosensitizes Cancer Cells by Activating the NADPH/ROS Pathway

The radioresistance of tumors affect the outcome of radiotherapy. Accumulating data suggest that 1α,25(OH)₂D₃ is a potential anti-oncogenic molecule in various cancers. In the present study, we investigated the radiosensitive effects and underlying mechanisms of 1α,25(OH)₂D₃ in vitro and in vivo. We found that 1α,25(OH)₂D₃ enhanced the radiosensitivity of lung cancer and ovarian cancer cells by promoting the NADPH oxidase-ROS-apoptosis axis. Compared to the group that only received radiation, the survival fraction and self-renewal capacity of cancer cells treated with a combination of 1α,25(OH)₂D₃ and radiation were decreased. Both apoptosis and ROS were significantly increased in the combination group compared with the radiation only group. Moreover, N-acetyl-L-cysteine, a scavenger of intracellular ROS, reversed the apoptosis and ROS induced by 1α,25(OH)₂D₃, indicating that 1α,25(OH)₂D₃ enhanced the radiosensitivity of cancer cells in vitro by promoting ROS-induced apoptosis. Moreover, our results demonstrated that 1α,25(OH)₂D₃ promoted the ROS level via activating NADPH oxidase complexes, NOX4, p22^phox, and p47^phox. In addition, knockdown of the vitamin D receptor (VDR) abolished the radiosensitization of 1α,25(OH)₂D₃, which confirmed that 1α,25(OH)₂D₃ radiosensitized tumor cells that depend on VDR. Similarly, our study also evidenced that vitamin D₃ enhanced the radiosensitivity of cancer cells in vivo and extended the overall survival of mice with tumors. In summary, these results demonstrate that 1α,25(OH)₂D₃ enhances the radiosensitivity depending on VDR and activates the NADPH oxidase-ROS-apoptosis axis. Our findings suggest that 1α,25(OH)₂D₃ in combination with radiation enhances lung and ovarian cell radiosensitivity, potentially providing a novel combination therapeutic strategy.

m6A Reader YTHDC2 Promotes Radiotherapy Resistance of Nasopharyngeal Carcinoma via Activating IGF1R/AKT/S6 Signaling Axis

N6-methyladenosine (m⁶A) modification has been reported as a critical regulator of gene transcript expression. Although m⁶A modification plays important roles in tumor development, its role in therapeutic resistance remains unknown. In this study, we aimed to examine the expression level of m⁶A-modification related proteins and elucidate the effect of m⁶A-related proteins on radiation response in nasopharyngeal carcinoma (NPC). Among the genes that participated in m⁶A modification, YTHDC2, a m⁶A reader, was found to be consistently highly expressed in radioresistant NPC cells. Knocking down of YTHDC2 expression in radioresistant NPC cells improved the therapeutic effect of radiotherapy in vitro and in vivo, whereas overexpression of YTHDC2 in radiosensitive NPC cells exerted an opposite effect. Bioinformatics and mechanistic studies revealed that YTHDC2 could physically bound to insulin-like growth factor 1 receptor (IGF1R) messenger RNA and promoted translation initiation of IGF1R mRNA, which in turn activated the IGF1R-AKT/S6 signaling pathway. Thus, the present study suggests that YTHDC2 promotes radiotherapy resistance of NPC cells by activating the IGF1R/ATK/S6 signaling axis and may serve as a potential therapeutic target in radiosensitization of NPC cells.

Hydroxychloroquine-loaded hollow mesoporous silica nanoparticles for enhanced autophagy inhibition and radiation therapy

Radiotherapy (RT) is a major modality for cancer treatment, along with surgery and chemotherapy. Despite its therapeutic effect, the recurrence and metastasis of tumors due to the acquired resistance of cancer cells to RT remain significant clinical problems. Therefore, it is imperative to overcome radioresistance and improve radiosensitivity in cancer patients. Here, we synthesized hydroxychloroquine (HCQ)-loaded hollow mesoporous silica nanoparticles (HMSNs) to enable effective inhibition of radiation-induced cytoprotective autophagy and enhance the therapeutic efficacy of RT. HCQ-HMSN-treated HCT116 colon cancer cells showed a 200-fold higher intracellular uptake of HCQ than that of free HCQ-treated cells, thereby effectively inhibiting the radiation-induced autophagy of cancer cells. In vivo imaging and therapy studies of a tumor xenograft model showed preferential accumulation of HCQ-HMSNs in tumor tissues and significant enhancement of RT by inhibiting autophagy in the tumor sites. Histopathology analyses of major organs, blood chemistry profiles, and changes in body weights of mice confirmed the good biocompatibility of HCQ-HMSNs.

1,25-Dihydroxyvitamin D attenuates diabetic cardiac autophagy and damage by vitamin D receptor-mediated suppression of FoxO1 translocation

Cardiovascular abnormalities are one of the most important complications associated with diabetes. However, the effect of 1, 25-dihydroxyvitamin D (1,25D) on the diabetic heart and the associated regulatory mechanisms are not well appreciated. Here, we report that activation of the vitamin D receptor (VDR) by 1,25D depresses autophagic activity by inhibiting nuclear FoxO1 translocation to attenuate diabetic heart damage. Treatment with 1,25D improved oral glucose tolerance test outcomes, fasting blood glucose levels and CK-MB release in Zucker diabetic fatty (ZDF, fa/fa) rats. Moreover, 1,25D intervention decreased the expression of Bcl-2, Bax, cleaved caspase-3, nuclear FoxO1, LC3II/LC3I and Beclin1 in the hearts of ZDF rats. However, VDR was noticeably up-regulated by 1,25D, which was inhibited in diabetic hearts. In the cardiomyocyte cell line H9c2, further accumulation of LC3II and the augmentation of p62 after treatment with high glucose and chloroquine confirmed increased autophagic activity in diabetic hearts. Moreover, increased Bcl-2 and Bax levels were observed after treatment with an agonist (rapamycin) and antagonist (3MA) of autophagy in high-glucose-cultured cells. The knockdown of VDR with siRNA further induced the expression of LC3II and FoxO1 translocation and altered the Bax/Bcl-2 ratio in high-glucose-exposed cells, and these effects were suppressed by treatment with 1,25D or an inhibitor of FoxO1 transcriptional activity. In summary, 1,25D supplementation attenuated diabetic heart-related cardiac autophagy and damage by activating the VDR to inhibit the nuclear translocation of FoxO1.

Functions and mechanisms of circular RNAs in cancer radiotherapy and chemotherapy resistance

Circular RNAs (circRNAs), one type of non-coding RNA, were initially misinterpreted as nonfunctional products of pre-mRNA mis-splicing. Currently, circRNAs have been proven to manipulate the functions of diverse molecules, including non-coding RNAs, mRNAs, DNAs and proteins, to regulate cell activities in physiology and pathology. Accumulating evidence indicates that circRNAs play critical roles in tumor genesis, development, and sensitivity to radiation and chemotherapy. Radiotherapy and chemotherapy are two primary types of intervention for most cancers, but their therapeutic efficacies are usually retarded by intrinsic and acquired resistance. Thus, it is urgent to develop new strategies to improve therapeutic responses. To achieve this, clarification of the underlying mechanisms affecting therapeutic responses in cancer is needed. This review summarizes recent progress and mechanisms of circRNAs in cancer resistance to radiation and chemotherapy, and it discusses the limitations of available knowledge and potential future directions.

Enhancement of sorafenib-mediated death of Hepatocellular carcinoma cells by Carnosic acid and Vitamin D2 analog combination

Hepatocellular carcinoma (HCC) is the most common form of liver cancer and it is the third leading cause of global cancer mortality. Sorafenib (Sf) is the first oral multi-kinase inhibitor approved for systemic treatment of advanced HCC, and can prolong survival, although only for three months longer than placebo treated patients. Preclinical studies showed that active forms of vitamin D can induce cell differentiation and regulate cell survival in several cell types, and epidemiological data link vitamin D insufficiency to an increased risk of neoplastic diseases, suggesting a potentially important role of vitamin D in cancer therapy. Other studies showed that the effect of vitamin D analogs on human neoplastic cells is potentiated by carnosic acid (CA), a plant polyphenol with anti-oxidant properties. Here we tested if the addition of the vitamin D2 analog Doxercalciferol (D2) together with CA can enhance the cytotoxic effect of Sf on HCC cell lines Huh7 (Sf-sensitive) and HCO2 (Sf-resistant). Indeed, this combination increased HCC cell death in cell lines, enhancing autophagy as well as apoptosis. Autophagy was confirmed by increased cytoplasmic vacuolation, perinuclear aggregation of LC3, and elevated protein levels of autophagy markers Beclin1, Atg3, and LC3. These results suggest that a regimen which combines a vitamin D2 analog/CA mixture with Sf can be a novel and promising therapeutic option for the treatment of HCC.

The Switch between Protective and Nonprotective Autophagy; Implications for Autophagy Inhibition as a Therapeutic Strategy in Cancer

Autophagy, a process of cellular self-degradation and cell survival whereby the cell generates energy and metabolic intermediates under conditions of stress (i.e., nutrient deprivation), is also commonly induced in tumor cells in response to chemotherapy and radiation. While chemotherapy-induced autophagy and radiation-induced autophagy are generally considered to have cytoprotective functions, thereby reducing tumor cell sensitivity (and potentially conferring resistance) to various treatment modalities, autophagy can also be nonprotective; furthermore, the nature of the autophagy can be altered via the “autophagic switch” depending on such factors as the p53 status of the tumor cells. Defective or compromised autophagy has also been associated with neurodegenerative diseases, raising concerns as to the impact of autophagy inhibition on normal tissue function. Furthermore, the impact of autophagy inhibition on the immune system response to therapy as well as the influence of autophagy inhibition in combination with chemotherapy or radiation on critical tissue sites such as the bone marrow remain uncertain. These are factors requiring serious consideration within the context of current clinical efforts to exploit autophagy inhibition as a therapeutic strategy in cancer.

Autophagy and Tumour Radiotherapy

Radiotherapy is an important component of cancer treatment modalities. With the rapid development of three-dimensional conformal, intensity-modulated, image-guided radiotherapy and the efficacy of radiotherapy continues to improve. Autophagy, as a catabolic process, is characterized by the formation of a double-membrane vesicle. Radiotherapy is known to induce autophagy in both cancer and normal cells. Here, we reviewed the interaction of radiotherapy and autophagy in the process of cancer treatment. The potential role of autophagy modification in enhancing radiotherapy treatment will also be reviewed.

Inhibition of endoplasmic reticulum stress-induced autophagy promotes the killing effect of X-rays on sarcoma in mice

Endoplasmic reticulum (ER) stress is a conserved cellular process for cells to clear unfolded or misfolded proteins and maintain cell homeostasis under stress conditions. Autophagy may act as a pro-survival strategy to cope with multiple stress conditions in tumor progression and distant metastasis. Although many studies have demonstrated that there is a close correlation between radiation-induced ER stress and autophagy, the molecular mechanisms currently remain unclear. In the present study, we performed an in vivo study concerning the effect of autophagy induced by ER stress on the radiosensitivity of mouse sarcoma using X-rays. Our results documented that X-rays could induce ER stress in sarcoma and then autophagy was activated by unfolded protein response (UPR) through the IRE1-JNK-pBcl2-Beclin1 signaling axis. The induction of autophagy caused a decline in cell apoptosis while inhibiting the autophagy resulted in increased apoptosis and inhibition of tumor progression. Combined treatment of X-ray exposure and chloroquine increased ER stress-related apoptosis and enhanced the radiosensitivity of mouse sarcoma that was not sensitive to X-ray irradiation alone. Thus, our study indicates that inhibition of ER stress-induced autophagy might be a novel strategy to improve the efficacy of radiotherapy against radioresistant sarcoma.

Autophagy dysfunctions associated with cancer cells and their therapeutic implications

Genomic analysis of human cancers indicates that the loss or mutation of core autophagy related genes, (ATG) is uncommon, whereas oncogenic events that activate autophagy and lysosomal biogenesis have been identified. Several studies have demonstrated that autophagy plays a wide variety of physiological and pathophysiological roles in cells: a cellular process that maintains the homeostasis of the normal cell, while self-defects can lead to a lawsuit to accelerate tumorigenesis and developing diseases, such as cancer. Depending on different contexts, autophagy dysfunctions may play a role: neutral, tumor-suppressive, or tumor-promoting. The process of autophagy may function in tumor suppression by mitigating metabolic stress and, in concert with apoptosis, by preventing tumor cell death by necrosis. In this case, optimal combination of autophagy inhibition (CQ, HCQ) with other conventional therapies - chemo or radiotherapy in a variety of tumor types in different phases can be successful approaches for improve the effect of anticancer therapies. This review examines recent insights of the molecular mechanism of autophagy and the potential roles of autophagy in cell death, cancer development, overview of the most recent therapeutic strategies involving autophagy modulators in cancer prevention and therapeutic opportunities.

Combined analysis and validation for DNA methylation and gene expression profiles associated with prostate cancer

BACKGROUND

Prostate cancer (PCa) is a malignancy cause of cancer deaths and frequently diagnosed in male. This study aimed to identify tumor suppressor genes, hub genes and their pathways by combined bioinformatics analysis.

METHODS

A combined analysis method was used for two types of microarray datasets (DNA methylation and gene expression profiles) from the Gene Expression Omnibus (GEO). Differentially methylated genes (DMGs) were identified by the R package minfi and differentially expressed genes (DEGs) were screened out via the R package limma. A total of 4451 DMGs and 1509 DEGs, identified with nine overlaps between DMGs, DEGs and tumor suppressor genes, were screened for candidate tumor suppressor genes. All these nine candidate tumor suppressor genes were validated by TCGA (The Cancer Genome Atlas) database and Oncomine database. And then, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed by DAVID (Database for Annotation, Visualization and Integrated Discovery) database. Protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. At last, Kaplan-Meier analysis was performed to validate these genes.

RESULTS

The candidate tumor suppressor genes were IKZF1, PPM1A, FBP1, SMCHD1, ALPL, CASP5, PYHIN1, DAPK1 and CASP8. By validation in TCGA database, PPM1A, DAPK1, FBP1, PYHIN1, ALPL and SMCHD1 were significant. The hub genes were FGFR1, FGF13 and CCND1. These hub genes were identified from the PPI network, and sub-networks revealed by these genes were involved in significant pathways.

CONCLUSION

In summary, the study indicated that the combined analysis for identifying target genes with PCa by bioinformatics tools promote our understanding of the molecular mechanisms and underlying the development of PCa. And the hub genes might serve as molecular targets and diagnostic biomarkers for precise diagnosis and treatment of PCa.

Autophagy induced by low concentrations of crotonaldehyde promotes apoptosis and inhibits necrosis in human bronchial epithelial cells

Crotonaldehyde is a common environmental contaminant. Autophagy, apoptosis, and necrosis, were all respectively reported to be induced by crotonaldehyde. However, the relationships between programmed cell deaths, especially between autophagy and apoptosis, have not been elucidated. In the present study, alterations of autophagy, apoptosis and necrosis were investigated in human bronchial epithelial cells (BEAS-2B) exposed to crotonaldehyde, and effects of autophagy on apoptosis and necrosis were detected. We found that a high concentration (160 μmol/L, μM) of crotonaldehyde did not induce apoptosis, while a low concentration (80 μM) of crotonaldehyde induced autophagy, apoptosis and necrosis. In 80 μM crotonaldehyde-exposed BEAS-2B cells, autophagy and apoptosis exhibited a trend of increasing prior to decreasing with the increase of time, while the time point inducing the highest level of autophagy was 2 h, and that of apoptosis was 4 h. With the pretreatment of bafilomycin A₁, the apoptosis was inhibited and the necrosis was enhanced significantly in cells exposed to 80 μM crotonaldehyde. Autophagy mediated the induction of apoptosis via the intrinsic apoptotic pathway. The results indicate that autophagy mediates the initiation of apoptosis and plays a role in protecting from necrosis in low concentrations of crotonaldehyde-exposed BEAS-2B cells.

Discovery of novel nonsteroidal VDR agonists with novel diarylmethane skeleton for the treatment of breast cancer

Vitamin D receptor (VDR) is recognized as a potential target for the treatment of breast cancer which is the most common malignancy among women in the world. In this study, a series of nonsecosteroidal VDR agonists with a novel diarylmethane skeleton was designed, synthesized and the anti-tumor activities of these compounds were determined. Compound 28 was identified as the most effective agents in reducing the viability of MCF-7 cells, with a low IC₅₀ via the inhibition of cell cycle and induction of apoptosis by regulating the expression of p21, Bcl2 and Bax. In addition, compound 28 showed high VDR-binding affinity and displayed significant VDR-agonistic activities. Further investigation revealed that compound 28 inhibited tumor growth in an orthotopic breast-tumor model without causing hypercalcemia which is the main side effect of secosteroidal VDR modulators. In summary, these findings discovered novel VDR modulators as promising candidates for cancer chemotherapy.

Down-regulated LncR-MALAT1 suppressed cell proliferation and migration by inactivating autophagy in bladder cancer

Long non-coding RNA-metastasis-associated lung adenocarcinoma transcript (LncR-MALAT) is highly expressed in a variety of tumors, which can affect the progression of tumor cells. LncR-MALAT1 was reported to affect the proliferation of pancreatic cancer and glioma cells by regulating autophagy, but how LncR-MALAT1 affects the proliferation and invasion of various cancer cells by regulating autophagy in bladder cancer has not been reported. Therefore, in this study, we aimed to investigate the effect of LncR-MALAT1 on cell proliferation, apoptosis, invasion and autophagy of bladder cancer and the possible mechanism in vitro. The results showed that LncR-MALAT1 was highly expressed in bladder cancer tissues and cells. The silence of LncR-MALAT1 inhibited the proliferation and invasion and promoted apoptosis in bladder cancer cells. In addition, MALAT1 shRNA down-regulated the expression of Beclin1 and the LC3 II/I ratio, enhanced the expression of p62 and played a significant role in autophagy inhibition. By further investigating the relevant regulatory mechanisms, we found that MALATI shRNA reduced the phosphorylation of AMPK and increased the phosphorylation level of mTOR, thereby inhibiting the activation of the AMPK/mTOR pathway. It is noteworthy that the AMPK/mTOR pathway activator, metformin, partially reversed the effect of MALAT1 shRNA on the inhibition of autophagy in bladder cancer cells. At the same time, the proliferation and invasion ability of HT-1376 cells inhibited by MALAT1 shRNA were also enhanced. The results showed that down-regulation of LncR-MALAT1 could inhibit the proliferation and invasion of bladder cancer cells by attenuating autophagy via the regulation of the AMPK/mTOR pathway.

Long non-coding RNA-metastasis-associated lung adenocarcinoma transcript (LncR-MALAT) is highly expressed in a variety of tumors, which can affect the progression of tumor cells.

Activating Autophagy Enhanced the Antitumor Effect of Antibody Drug Conjugates Rituximab-Monomethyl Auristatin E

Background

Antibody drug conjugate (ADC) showed potent therapeutic efficacy in several types of cancers. The role of autophagy in antitumor effects of ADC remains unclear.

Methods

In this study, the ADC, Rituximab-monomethyl auristatin E (MMAE) with a Valine–Citrulline cleavable linker, was designed to investigate its therapeutic efficacy against non-Hodgkin lymphoma (NHL) as well as the underlying mechanisms. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) was used to detect growth inhibition in B-cell lymphoma cell lines, Ramos and Daudi cells, which were treated by Rituximab-MMAE alone or combined with autophagy conditioner. Apoptosis was detected by flow cytometry and immunohistochemistry, and apoptosis inhibitor was employed to discover the relationship between autophagy and apoptosis during the Rituximab-MMAE treatment. Autophagy was determined by three standard techniques which included confocal microscope, transmission electron microscope, and western blots. Ramos xenograft tumors in BALB/c nude mice were established to investigate the antitumor effect of combination use of Rituximab-MMAE and autophagy conditioner in B-NHL therapy.

Results

Our results showed that Rituximab-MMAE elicited caspase-3-dependent apoptosis in NHL cells and exhibited potent therapeutic efficacy in vivo. Autophagy, which was characterized by upregulated light chain 3-II expression, and accumulation of autophagosomes, was triggered during the Rituximab-MMAE treatment. Meanwhile, inactivation of Akt/mTOR pathway was shown to be involved in the autophagy triggered by Rituximab-MMAE, indicating a probable mechanism of the ADC-initiated autophagy. Importantly, inhibition of autophagy by chloroquine suppressed the Rituximab-MMAE-induced apoptosis, while activating autophagy by rapamycin significantly enhanced the therapeutic effect of Rituximab-MMAE both in vitro and in vivo.

Conclusion

Our data elucidated the critical relationship between autophagy and apoptosis in Rituximab-MMAE-based therapy and highlighted the potential approach for NHL therapy by combined administration of the ADC and autophagy activator.

GSK-3β inhibits autophagy and enhances radiosensitivity in non-small cell lung cancer

Background

Radiotherapy is one of the most common and effective treatment methods for cancer, and improving the radiosensitivity of tumor tissues during the treatment process is vital. We report the mechanisms of glycogen synthase kinase 3 (GSK-3) β-regulated autophagy and the effects of autophagy on radiosensitivity in non-small cell lung cancer (NSCLC).

Method

Immunohistochemical staining was performed to determine GSK-3β tissue expression in 89 NSCLC patients with follow-up data and the expression status of GSK-3β and autophagy in NSCLC tissues after X-ray radiotherapy. Western blots were used to quantitate changes in autophagy-related protein expression after A549 cells were treated with GSK-3β inhibitors and after H460 cells were transfected with GSK-3β mutants with different activities and X-ray irradiated. Clonogenic assays were used to measure the effect of autophagy on cellular proliferation.

Results

GSK-3β expression positively correlated with NSCLC differentiation (P < 0.05), and GSK-3β negativity was associated with a better prognosis in 89 NSCLC patients. After X-ray irradiation, the expression levels of GSK-3β and p62 were decreased in NSCLC tissues, and the expression levels of the autophagy-related protein LC3 were increased. A549 and H460 cells were selected as representative GSK-3β-high and GSK-3β-low expression cell lines. After transfecting H460 cells with different GSK-3β mutants [wild type GSK-3β (GSK-3β-WT), constitutively active GSK-3β (GSK-3β-S9A), and catalytically inactive GSK-3β (GSK-3β-K85R)] and subjecting these cells to X-ray irradiation, AMPK and LC3 expression levels decreased, and p62 expression levels increased. These effects were particularly significant for the GSK-3β-S9A mutant. In A549 cells, after GSK-3β inhibition and X-ray irradiation, AMPK and LC3 protein expression levels increased. Moreover, when autophagy was inhibited, cell proliferation decreased.

Conclusion

Our studies revealed that GSK-3β expression is associated with NSCLC differentiation, and patients with GSK-3β-negative tumors had a better prognosis. X-ray irradiation inhibited GSK-3β expression and promoted autophagy. Therefore, GSK-3β inhibits autophagy and enhances the radiosensitivity of NSCLC cells.

Autophagy inhibition enhances radiosensitivity of Eca‑109 cells via the mitochondrial apoptosis pathway

Autophagy inhibition is crucial for the improvement of the efficacy of radiotherapy in cancer. The aim of the present study was to determine the potential therapeutic value of autophagy and its correlation with mitochondria in human esophageal carcinoma cells following treatment with ionizing radiation (IR). Autophagy in Eca-109 cells was induced under poor nutrient conditions. The formation of autophagic vacuoles was monitored using electron microscopy. In addition, cell apoptosis after IR and mitochondrial membrane potential (MMP) were analyzed by flow cytometry. LC3, beclin-1, cytochrome c and apoptosis-related proteins were assayed by western blotting. A nude mouse xenograft model was also employed to verify the biological effects and mechanisms underlying autophagy in vivo. The formed autophagic vesicles and increased LC3 II/LC3 I ratio indicated marked induction of autophagy by Earle's balanced salt solution (EBSS) in Eca-109 cells. 3-Methyladenine or LY294002 significantly antagonized EBSS-induced autophagy and increased apoptosis of irradiated cells, suggesting that autophagy inhibition conferred radiosensitivity in vitro. Notably, IR induced prominent release of cytochrome c and Bax activation, and decreased Bcl-2 and MMP expression in Eca-109 cells under poor nutrient conditions. Of note, these changes were more prominent following pretreatment with autophagy inhibitors. In vivo, IR treatment mildly delayed tumor growth, but the radiotherapeutic effect was improved significantly by abolishing autophagy. Furthermore, mitochondrial signaling was investigated in the Eca-109 xenograft nude mice model, and the results were consistent with the in vitro study. Therefore, the mitochondrial pathway may be associated with improvement of radiosensitivity in Eca-109 cells.

Vitamin D and breast cancer: Past and present

The presence of the vitamin D receptor in mammary gland and breast cancer has been recognized since the early 1980s, and multiple pre-clinical studies have demonstrated that its ligand 1,25D modulates normal mammary gland development and sensitivity to carcinogenesis. Although studies have characterized many 1,25D responsive targets in normal mammary cells and in breast cancers, validation of relevant targets that regulate cell cycle, apoptosis, autophagy and differentiation, particularly in vivo, has been challenging. Vitamin D deficiency is common in breast cancer patients and some evidence suggests that low vitamin D status enhances the risk for disease development or progression. Model systems of carcinogenesis have provided evidence that both VDR expression and 1,25D actions change with transformation but clinical data regarding vitamin D responsiveness of established tumors is limited and inconclusive. Because breast cancer is heterogeneous, analysis of VDR actions in specific molecular subtypes of the disease is necessary to clarify the conflicting data. Genomic, proteomic and metabolomic analyses of in vitro and in vivo model systems is also warranted to comprehensively understand the network of vitamin D regulated pathways in the context of breast cancer heterogeneity.

Overcoming resistance to mitochondrial apoptosis by BZML-induced mitotic catastrophe is enhanced by inhibition of autophagy in A549/Taxol cells

OBJECTIVES

Our previous in vitro study showed that 5-(3, 4, 5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) is a novel colchicine binding site inhibitor with potent anti-cancer activity against apoptosis resistance in A549/Taxol cells through mitotic catastrophe (MC). However, the mechanisms underlying apoptosis resistance in A549/Taxol cells remain unknown. To clarify these mechanisms, in the present study, we investigated the molecular mechanisms of apoptosis and autophagy, which are closely associated with MC in BZML-treated A549 and A549/Taxol cells.

METHODS

Xenograft NSCLC models induced by A549 and A549/Taxol cells were used to evaluate the efficacy of BZML in vivo. The activation of the mitochondrial apoptotic pathway was assessed using JC-1 staining, Annexin V-FITC/PI double-staining, a caspase-9 fluorescence metric assay kit and western blot. The different functional forms of autophagy were distinguished by determining the impact of autophagy inhibition on drug sensitivity.

RESULTS

Our data showed that BZML also exhibited desirable anti-cancer activity against drug-resistant NSCLC in vivo. Moreover, BZML caused ROS generation and MMP loss followed by the release of cytochrome c from mitochondria to cytosol in both A549 and A549/Taxol cells. However, the ROS-mediated apoptotic pathway involving the mitochondria that is induced by BZML was only fully activated in A549 cells but not in A549/Taxol cells. Importantly, we found that autophagy acted as a non-protective type of autophagy during BZML-induced apoptosis in A549 cells, whereas it acted as a type of cytoprotective autophagy against BZML-induced MC in A549/Taxol cells.

CONCLUSIONS

Our data suggest that the anti-apoptosis property of A549/Taxol cells originates from a defect in activation of the mitochondrial apoptotic pathway, and autophagy inhibitors can potentiate BZML-induced MC to overcome resistance to mitochondrial apoptosis.