Inhibition LC3B can increase chemosensitivity of ovarian cancer cells

TRIM47 inhibits cisplatin chemosensitivity and endoplasmic reticulum stress-induced apoptosis of ovarian cancer cells

Ovarian cancer (OC) is the fifth most common cause of death in women worldwide. Chemoresistance is a key reason for treatment failure, causing high mortality. As a member of the tripartite motif-containing (TRIM) protein family, tripartite motif 47 (TRIM47) plays a vital role in the carcinogenesis and drug resistance of various cancers. This study investigated the impact and mechanisms of TRIM47 on cisplatin (DDP) chemosensitivity and apoptosis in OC. OC cell viability was assessed with a cell counting kit-8 assay and OC cell apoptosis was assessed using flow cytometry, caspase-3 and caspase-9 activity, and Bax and Bcl-2 expression assays while gene and protein expression were assessed using qRT-PCR and Western blot assays. The expression of TRIM47 was significantly increased in both DDP-resistant tissues from patients with OC tissues and in cancer cell lines compared with that in normal tissue or parental cell lines. The increased level of TRIM47 correlated with poor prognosis in patients with OC. Functional assays demonstrated that TRIM47 promoted DDP resistance both in vitro and in vivo. The increased viability and reduced apoptosis of OC cells induced by TRIM47 can be rescued by the endoplasmic reticulum (ER) stress-inducer tunicamycin, suggesting that TRIM47 inhibits OC cell apoptosis by suppressing ER stress. Therefore, TRIM47 may be targeted as a therapeutic strategy for DDP resistance in OC.

Computational Design of Novel Cyclic Peptides Endowed with Autophagy-Inhibiting Activity on Cancer Cell Lines

(1) Autophagy plays a significant role in development and cell proliferation. This process is mainly accomplished by the LC3 protein, which, after maturation, builds the nascent autophagosomes. The inhibition of LC3 maturation results in the interference of autophagy activation. (2) In this study, starting from the structure of a known LC3B binder (LIR2-RavZ peptide), we identified new LC3B ligands by applying an in silico drug design strategy. The most promising peptides were synthesized, biophysically assayed, and biologically evaluated to ascertain their potential antiproliferative activity on five humans cell lines. (3) A cyclic peptide (named Pep6), endowed with high conformational stability (due to the presence of a disulfide bridge), displayed a Kd value on LC3B in the nanomolar range. Assays accomplished on PC3, MCF-7, and A549 cancer cell lines proved that Pep6 exhibited cytotoxic effects comparable to those of the peptide LIR2-RavZ, a reference LC3B ligand. Furthermore, it was ineffective on both normal prostatic epithelium PNT2 and autophagy-defective prostate cancer DU145 cells. (4) Pep6 can be considered a new autophagy inhibitor that can be employed as a pharmacological tool or even as a template for the rational design of new small molecules endowed with autophagy inhibitory activity.

Chloroquine enhances the efficacy of chemotherapy drugs against acute myeloid leukemia by inactivating the autophagy pathway

Current therapy for acute myeloid leukemia (AML) is largely hindered by the development of drug resistance of commonly used chemotherapy drugs, including cytarabine, daunorubicin, and idarubicin. In this study, we investigated the molecular mechanisms underlying the chemotherapy drug resistance and potential strategy to improve the efficacy of these drugs against AML. By analyzing data from ex vivo drug-response and multi-omics profiling public data for AML, we identified autophagy activation as a potential target in chemotherapy-resistant patients. In THP-1 and MV-4-11 cell lines, knockdown of autophagy-regulated genes ATG5 or MAP1LC3B significantly enhanced AML cell sensitivity to the chemotherapy drugs cytarabine, daunorubicin, and idarubicin. In silico screening, we found that chloroquine phosphate mimicked autophagy inactivation. We showed that chloroquine phosphate dose-dependently down-regulated the autophagy pathway in MV-4-11 cells. Furthermore, chloroquine phosphate exerted a synergistic antitumor effect with the chemotherapy drugs in vitro and in vivo. These results highlight autophagy activation as a drug resistance mechanism and the combination therapy of chloroquine phosphate and chemotherapy drugs can enhance anti-AML efficacy.

Micelle encapsulation zinc-doped copper oxide nanocomposites reverse Olaparib resistance in ovarian cancer by disrupting homologous recombination repair

Micelle Encapsulation Zinc-doped copper oxide nanocomposites (MEnZn-CuO NPs) is a novel doped metal nanomaterial prepared by our group based on Zinc doped copper oxide nanocomposites (Zn-CuO NPs) using non-micellar beam. Compared with Zn-CuO NPs, MEnZn-CuO NPs have uniform nanoproperties and high stability. In this study, we explored the anticancer effects of MEnZn-CuO NPs on human ovarian cancer cells. In addition to affecting cell proliferation, migration, apoptosis and autophagy, MEnZn-CuO NPs have a greater potential for clinical application by inducing HR repair defects in ovarian cancer cells in combination with poly (ADP-ribose) polymerase inhibitors for lethal effects.

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.

Non-coding RNAs: The recently accentuated molecules in the regulation of cell autophagy for ovarian cancer pathogenesis and therapeutic response

Autophagy is a self-recycling and conserved process, in which the senescent cytoplasmic components are degraded in cells and then recycled to maintain homeostatic balance. Emerging evidence has suggested the involvement of autophagy in oncogenesis and progression of various cancers, such as ovarian cancer (OC). Meanwhile, the non-coding RNAs (ncRNAs) frequently regulate the mRNA transcription and other functional signaling pathways in cell autophagy, displaying promising roles in human cancer pathogenesis and therapeutic response. This article mainly reviews the cutting-edge research advances about the interactions between ncRNAs and autophagy in OC. This review not only summarizes the underlying mechanisms of dynamic ncRNA-autophagy association in OC, but also discusses their prognostic implications and therapeutic biomarkers. The aim of this review was to provide a more in-depth knowledge framework exploring the ncRNA-autophagy crosstalk and highlight the promising treatment strategies for OC patients.

Autophagy orchestrates resistance in hepatocellular carcinoma cells

Treatment resistance is one of the major barriers for therapeutic strategies in hepatocellular carcinoma (HCC). Many studies have indicated that chemotherapy and radiotherapy induce autophagy machinery (cell protective autophagy) in HCC cells. In addition, many experiments report a remarkable crosstalk between treatment resistance and autophagy pathways. Thus, autophagy could be one of the key factors enabling tumor cells to hinder induced cell death after medical interventions. Therefore, extensive research on the molecular pathways involved in resistance induction and autophagy have been conducted to achieve the desired therapeutic response. The key molecular pathways related to the therapy resistance are TGF-β, MAPK, NRF2, NF-κB, and non-coding RNAs. In addition, EMT, drug transports, apoptosis evasion, DNA repair, cancer stem cells, and hypoxia could have considerable impact on the hepatoma cell's response to therapies. These mechanisms protect tumor cells against various treatments and many studies have shown that each of them is connected to the molecular pathways of autophagy induction in HCC. Hence, autophagy inhibition may be an effective strategy to improve therapeutic outcome in HCC patients. In this review, we further highlight how autophagy leads to poor response during treatment through a complex molecular network and how it enhances resistance in primary liver cancer. We propose that combinational regimens of approved HCC therapeutic protocols plus autophagy inhibitors may overcome drug resistance in HCC therapy.

The Vault Complex Is Significantly Involved in Therapeutic Responsiveness of Endocrine Tumors and Linked to Autophagy under Chemotherapeutic Conditions

Cancers display dynamic interactions with their complex microenvironments that influence tumor growth, invasiveness, and immune evasion, thereby also influencing potential resistance to therapeutic treatments. The tumor microenvironment (TME) includes cells of the immune system, the extracellular matrix, blood vessels, and other cell types, such as fibroblasts or adipocytes. Various cell types forming this TME secrete exosomes, and molecules thereby released into the TME have been shown to be important mediators of cellular communication and interplay. Specific stressors in the TME, such as hypoxia, starvation, inflammation, and damage, can furthermore induce autophagy, a fundamental cellular process that degrades and recycles molecules and subcellular components, and recently it has been demonstrated that the small non-coding vault RNA1-1 plays a role as a regulator of autophagy and the coordinated lysosomal expression and regulation (CLEAR) network. Here, we demonstrate for the first time that intra-tumoral damage following effective therapeutic treatment is linked to specific intracellular synthesis and subsequent exosomal release of vault RNAs in endocrine tumors in vitro and in vivo. While we observed a subsequent upregulation of autophagic markers under classical chemotherapeutic conditions, a downregulation of autophagy could be detected under conditions strongly involving inflammatory cascades.

Autophagy: A challengeable paradox in cancer treatment

OBJECTIVE

Autophagy is an intracellular degradation pathway conserved in all eukaryotes from yeast to humans. This process plays a quality-control role by destroying harmful cellular components under normal conditions, maintaining cell survival, and establishing cellular adaptation under stressful conditions. Hence, there are various studies indicating dysfunctional autophagy as a factor involved in the development and progression of various human diseases, including cancer. In addition, the importance of autophagy in the development of cancer has been highlighted by paradoxical roles, as a cytoprotective and cytotoxic mechanism. Despite extensive research in the field of cancer, there are many questions and challenges about the roles and effects suggested for autophagy in cancer treatment. The aim of this study was to provide an overview of the paradoxical roles of autophagy in different tumors and related cancer treatment options.

METHODS

In this study, to find articles, a search was made in PubMed and Google scholar databases with the keywords Autophagy, Autophagy in Cancer Management, and Drug Design.

RESULTS

According to the investigation, some studies suggest that several advanced cancers are dependent on autophagy for cell survival, so when cancer cells are exposed to therapy, autophagy is induced and suppresses the anti-cancer effects of therapeutic agents and also results in cell resistance. However, enhanced autophagy from using anti-cancer drugs causes autophagy-mediated cell death in several cancers. Because autophagy also plays roles in both tumor suppression and promotion further research is needed to determine the precise mechanism of this process in cancer treatment.

CONCLUSION

We concluded in this article, autophagy manipulation may either promote or hinder the growth and development of cancer according to the origin of the cancer cells, the type of cancer, and the behavior of the cancer cells exposed to treatment. Thus, before starting treatment it is necessary to determine the basal levels of autophagy in various cancers.

Targeting the "undruggable": RNA-binding proteins in the spotlight in cancer therapy

Tumors refractory to conventional therapy belong to specific subpopulations of cancer cells, which have acquired a higher number of mutations/epigenetic changes than the majority of cancer cells. This property provides them the ability to become resistant to therapy. Aberrant expression of certain RNA-binding proteins (RBPs) can regulate the sensitivity of tumor cells to chemotherapeutic drugs by binding to specific regions present in the 3´-UTR of certain mRNAs to promote or repress mRNA translation or by interacting with other proteins (including RBPs) and non-coding RNAs that are part of ribonucleoprotein complexes. In particular, an increasing interest in the RBPs involved in chemoresistance has recently emerged. In this review, we discuss how RBPs are not only affected by chemotherapeutic treatments, but also play an active role in therapeutic responses via the direct modulation of crucial cancer-related proteins. A special focus is being placed on the development of therapeutic strategies targeting these RBPs.

MicroRNA-204-5p: A pivotal tumor suppressor

MicroRNAs (miRNAs) are a class of non-coding single-stranded RNA molecules with a length of approximately 18-25 nt nucleotides that regulate gene expression post-transcriptionally. MiR-204-5p originates from the sixth intron of the transient receptor potential cation channel subfamily M member 3 (TRPM3) gene. MiR-204-5p is frequently downregulated in various cancer types and is related to the clinicopathological characteristics and prognosis of cancer patients. So far, many studies have determined that miR-204-5p functions as a tumor suppressor for its extensive and powerful capacity to inhibit tumor proliferation, metastasis, autophagy, and chemoresistance in multiple cancer types. MiR-204-5p appears to be a promising prognostic biomarker and a therapeutic target for human cancers. This review summarized the latest advances on the role of miR-204-5p in human cancers.

Low-Intensity Focused Ultrasound Targeted Microbubble Destruction Enhanced Paclitaxel Sensitivity by Decreasing Autophagy in Paclitaxel-Resistant Ovarian Cancer

Ultrasound targeted microbubble destruction (UTMD) was introduced as a promising method to improve anti-tumor therapeutic efficacy, while minimizing side effects to healthy tissues. Nevertheless, the acoustical phenomenon behind the UTMD as well as the exact mechanisms of autophagy action involved in the increased anti-cancer response are still not fully understood. Therefore, we examined the drug resistance-reversing effects of low-intensity focused ultrasound with microbubble (LIFU+MB) in paclitaxel (PTX)-resistant ovarian cancer cells. Cell viability was evaluated using CCK8 (Cell Counting Kit-8), apoptosis was detected by flow cytometry, quantitative real-time PCR and Western blot were used to detect the expressions of mRNA and protein, and autophagy was observed by transmission electron microscopy (TEM). We revealed that the level of autophagy was increased (p < 0.05) in PTX-resistant ovarian cancer cells. Treatment of LIFU+MB combined with PTX can notably inhibit proliferation as well as increase apoptosis (p < 0.01) in drug-resistant cells. We proposed that LIFU+MB might affect the sensitivity of ovarian cancer cells to PTX by modulating autophagy. To verify the hypothesis, we analyzed the autophagy level of drug-resistant cells after the treatment of LIFU+MB and found that autophagy was significantly inhibited. Altogether, our findings demonstrated that LIFU+MB could reverse PTX resistance in ovarian cancer via inhibiting autophagy, which provides a novel strategy to improve chemosensitivity in ovarian cancer.

Double Insurance for OC: miRNA-Mediated Platinum Resistance and Immune Escape

Ovarian cancer (OC) is still the leading cause of death among all gynecological malignancies, despite the recent progress in cancer therapy. Immune escape and drug resistance, especially platinum-based chemotherapy, are significant factors causing disease progression, recurrence and poor prognosis in OC patients. MicroRNAs(miRNAs) are small noncoding RNAs, regulating gene expression at the transcriptional level. Accumulating evidence have indicated their crucial roles in platinum resistance. Importantly, they also act as mediators of tumor immune escape/evasion. In this review, we summarize the recent study of miRNAs involved in platinum resistance of OC and systematically analyses miRNAs involved in the regulation of OC immune escape. Further understanding of miRNAs roles and their possible mechanisms in platinum resistance and tumor escape may open new avenues for improving OC therapy.

Construction autophagy-related prognostic risk signature to facilitate survival prediction, individual treatment and biomarker excavation of epithelial ovarian cancer patients

Background

Existing clinical methods for prognosis evaluating for Epithelial Ovarian Cancer (EOC) patients had defects of invasive, unsystematic and subjective and little data are available for individualizing treatment, therefore, to identify potential prognostic markers and new therapeutic targets for EOC is urgently required.

Results

Expression of 232 autophagy-related genes (ARGs) in 354 EOC and 56 human ovarian surface epithelial specimens from 7 independent laboratories were analyzed, 31 mRNAs were identified as DEARGs. We did functional and pathway enrichment analysis and constructed protein–protein interaction network for all DEARGs. To screen out candidate DEARGs related to EOC patients’ survival and construct an autophagy-related prognostic risk signature, univariate and multivariate Cox proportional hazards models were established separately. Finally, 5 optimal independent prognostic DEARGs (PEX3, DNAJB9, RB1, HSP90AB1 and CXCR4) were confirmed and the autophagy-related risk model was established by the 5 prognostic DEARGs. The accuracy and robustness of the prognostic risk model for survival prediction were evaluated and verified by analyzing the correlation between EOC patients’ survival status, clinicopathological features and risk scores.

Conclusions

The autophagy-related prognostic risk model can be independently used to predict overall survival in EOC patients, it can also potentially assist in individualizing treatment and biomarker development.

[IL-17A/lL-17RA reduces cisplatin sensitivity of ovarian cancer SKOV3 cells by regulating autophagy]

OBJECTIVE

To investigate the effect of interleukin-17A (IL-17A) on chemosensitivity of ovarian cancer cells to cisplatin (DDP) and explore the mechanism in light of autophagy regulation.

METHODS

Ovarian cancer SKOV3 cells cultured in vitro were treated with different concentrations of DDP (1-20 μg/mL). MTT assay was used to observe the changes in proliferation of the treated cells and the effect of treatment with 100 ng/mL IL-17A for 24 h on DDP-induced apoptosis of SKOV3 cells. We then examined the expression of IL-17A receptor (IL-17RA) in SKOV3 cells using flow cytometry. Annexin V-FITC/PI double staining was used to detect the cell apoptosis rate, and early apoptosis of the cells was detected with JC-1 assay. A neutralizing monoclonal antibody (mAb) against IL-17RA was used to block IL-17RA. We also observed the effects of IL-17RA silencing mediated by a siRNA targeting IL-17RA (siRNA-IL-17RA) and treatment with 3-methyladenine (3-MA) for inhibiting autophagy on DDP-induced apoptosis of SKOV3 cells. The expressions of apoptosis-related proteins (Bcl-2, Bax, and cleaved caspase-3) and autophagy-related proteins (P62 and Beclin-1) in the treated cells were detected using Western blotting.

RESULTS

DDP increased the expression of IL-17RA in ovarian cancer SKOV3 cells. Treatment with IL-17A significantly reduced the susceptibility of SKOV3 cells to cisplatin-induced apoptosis (P < 0.05). DDP obviously augmented the expression of Beclin-1 and reduced the autophagy degradation substrate P62 protein in the cells (P < 0.05). IL-17A/IL-17RA strongly enhanced the DDPinducted autophagy of the cells (P < 0.05). Blocking autophagy with 3-MA significantly increased DDP- induced apoptosis of SKOV3 cells with IL-17RA silencing, lowered the expression of Bcl-2 and enhanced Bax expression in the cells (P < 0.05).

CONCLUSIONS

IL-17A/IL-17RA can decrease chemosensitivity of SKOV3 cells to DDP by upregulating DDP-induced autophagy.

Oncogenic Role of Long Noncoding RNAMALAT1 in Thyroid Cancer Progression through Regulation of the miR-204/IGF2BP2/m6A-MYC Signaling

Accumulating studies highlight the role of long noncoding RNAs (lncRNAs)/microRNAs (miRNAs)/messenger RNAs (mRNAs) as important regulatory networks in various human cancers, including thyroid cancer (TC). This study aimed to investigate a novel regulatory network dependent on lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in relation to TC development. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot were initially employed to detect the expression of MALAT1, insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2), and myelocytomatosis (MYC) in TC cells. Interactions among MALAT1, miR-204, and IGF2BP2 were then identified in vitro. The biological processes of proliferation, migration, invasion, and apoptosis were evaluated in vitro via gain- and loss-of-function experiments, followed by in vivo validation using xenograft mice. Our data indicated that MALAT1 and IGF2BP2 were highly expressed, while miR-204 was poorly expressed in TC. IGF2BP2 was verified as a target of miR-204. MALAT1 was found to upregulate IGF2BP2 and enhance MYC expression via m6A modification recognition by competitively binding to miR-204, conferring a stimulatory effect on proliferation, migration, and invasion of TC cells, which was accompanied by weakened tumor growth and cell apoptosis. Altogether, the central findings of our study suggest that MALAT1 contributes to TC progression through the upregulation of IGF2BP2 by binding to miR-204.

Mitochondria Participate in Chemoresistance to Cisplatin in Human Ovarian Cancer Cells

Ovarian cancer is an aggressive disease that affects about 300,000 patients worldwide, with a yearly death count of about 185,000. Following surgery, treatment involves adjuvant or neoadjuvant administration of taxane with platinum compounds cisplatin or carboplatin, which alkylate DNA through the same chemical intermediates. However, although platinum-based therapy can cure patients in a number of cases, a majority of them discontinues treatment owing to side effects and to the emergence of resistance. In this study, we focused on resistance to cisplatin and investigated whether metabolic changes could be involved. As models, we used matched pairs of cisplatin-sensitive (SKOV-3 and COV-362) and cisplatin-resistant (SKOV-3-R and COV-362-R) human ovarian carcinoma cells that were selected in vitro following exposure to increasing doses of the chemotherapy. Metabolic comparison revealed that resistant cells undergo a shift toward a more oxidative metabolism. The shift goes along with a reorganization of the mitochondrial network, with a generally increased mitochondrial compartment. More functional mitochondria in cisplatin-resistant compared with cisplatin-sensitive cells were associated to enzymatic changes affecting either the electron transport chain (SKOV-3/SKOV-3-R model) or mitochondrial coupling (COV-362/COV-362-R model). Our findings further indicate that the preservation of functional mitochondria in these cells could be due to an increased mitochondrial turnover rate, suggesting mitophagy inhibition as a potential strategy to tackle cisplatin-resistant human ovarian cancer progression. IMPLICATIONS: Besides classical mechanisms related to drug efflux and target modification, we report that preserving functional mitochondria is a strategy used by human ovarian cancer cells to resist to cisplatin chemotherapy.

The anti-tumourigenic effect of ellagic acid in SKOV-3 ovarian cancer cells entails activation of autophagy mediated by inhibiting Akt and activating AMPK

This study investigated the effect of ellagic acid (EA) on SKOV-3 cell growth and invasiveness and tested if the underlying mechanism involves modulating autophagy. Cells were treated with EA in the presence or absence of chloroquine (CQ), an autophagy inhibitor, compound C (CC), an AMPK inhibitor, or an insulin-like growth factor-1 (IGF-1), a PI3K/Akt activator. EA, at an IC₅₀ of 36.6 µmol/L, inhibited cell proliferation, migration, and invasion and induced cell apoptosis in SKOV-3 cells. These events were prevented by CQ. Also, EA increased levels of Beclin-1, ATG-5, LC3I/II, Bax, cleaved caspase-3/8 and reduced those of p62 and Bcl-2 in these cancer cells. Mechanistically, EA decreased levels of p-S6K1 (Thr³⁸⁹ ) and 4EBP-1 (Thr^37/46 ), two downstream targets of mTORC1, and p-Akt (Thr³⁰⁸ ) but increased levels of AMPK (Thr¹⁷² ) and p-raptor (Ser⁷⁹² ), a natural inhibitor of mTORC1. CC or IGF-1 alone partially prevented the effect of EA on cell survival, cell invasions, and levels of LDH, Beclin-1, and cleaved caspase-3. In conclusion, EA can inhibit SKOV-3 growth, migration, and invasion by activating cytotoxic autophagy mediated by inhibition of mTORC1 and Akt and activation of AMPK.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

Despite advances in diagnostic tools and therapeutic options, treatment resistance remains a challenge for many cancer patients. Recent studies have found evidence that autophagy, a cellular pathway that delivers cytoplasmic components to lysosomes for degradation and recycling, contributes to treatment resistance in different cancer types. A role for autophagy in resistance to chemotherapies and targeted therapies has been described based largely on associations with various signaling pathways, including MAPK and PI3K/AKT signaling. However, our current understanding of the molecular mechanisms underlying the role of autophagy in facilitating treatment resistance remains limited. Here we provide a comprehensive summary of the evidence linking autophagy to major signaling pathways in the context of treatment resistance and tumor progression, and then highlight recently emerged molecular mechanisms underlying autophagy and the p62/KEAP1/NRF2 and FOXO3A/PUMA axes in chemoresistance.