Inhibition of grade dependent autophagy in urothelial carcinoma increases cell death under nutritional limiting condition and potentiates the cytotoxicity of chemotherapeutic agent

Targeting autophagy in urological system cancers: From underlying mechanisms to therapeutic implications

The urological system, including kidneys, ureters, bladder, urethra and prostate is known to be vital for blood filtration, waste elimination and electrolyte balance. Notably, urological system cancers represent a significant portion of global cancer diagnoses and mortalities. The current therapeutic strategies for early-stage cancer primarily involve resection surgery, which significantly affects the quality of life of patients, whereas advanced-stage cancer often relies on less effective chemo- or radiotherapy. Recently, accumulating evidence has revealed that autophagy, a crucial process in which excess organelles or inclusions within cells are removed to maintain cell homeostasis, has numerous links to urological system cancers. In this review, we focus on summarizing the underlying two-sided mechanisms of autophagy in urological system cancers. We also review the current clinical drugs targeting autophagy, which demonstrate significant potential in improving treatment outcomes for urological system cancers. In addition, we provide an overview of the research status of novel small molecule compounds targeting autophagy that are in the preclinical stages of investigation. Furthermore, drug combinations based on autophagy modulation strategies in urological system cancers are systematically summarized and discussed. These findings provide comprehensive new insight for the future discovery of more autophagy-related drug candidates.

Machine learning-based autophagy-related prognostic signature for personalized risk stratification and therapeutic approaches in bladder cancer

OBJECTIVE

Bladder cancer (BCa) is a highly lethal urological malignancy characterized by its notable histological heterogeneity. Autophagy has swiftly emerged as a diagnostic and prognostic biomarker in diverse cancer types. Nonetheless, the currently accessible autophagy-related signature specific to BCa remains limited.

METHODS

A refined autophagy-related signature was developed through a 10-fold cross-validation framework, incorporating 101 combinations of machine learning algorithms. The performance of this signature in predicting prognosis and response to immunotherapy was thoroughly evaluated, along with an exploration of potential drug targets and compounds. In vitro and in vivo experiments were conducted to verify the regulatory mechanism of hub gene.

RESULTS

The autophagy-related prognostic signature (ARPS) has exhibited superior performance in predicting the prognosis of BCa compared to the majority of clinical features and other developed markers. Higher ARPS is associated with poorer prognosis and reduced sensitivity to immunotherapy. Four potential targets and five therapeutic agents were screened for patients in the high-ARPS group. In vitro and vivo experiments have confirmed that FKBP9 promotes the proliferation, invasion, and metastasis of BCa.

CONCLUSIONS

Overall, our study developed a valuable tool to optimize risk stratification and decision-making for BCa patients.

The role of autophagy dysregulation in low and high-grade nonmuscle invasive bladder cancer: A survival analysis and clinicopathological association

INTRODUCTION

Bladder cancer disproportionately affects men and often presents as nonmuscle-invasive bladder cancer (NMIBC). Despite initial treatments, the recurrence and progression of NMIBC are linked to autophagy. This study investigates the expression of autophagy genes (mTOR, ULK1, Beclin1, and LC3) in low and high-grade NMIBC, providing insights into potential prognostic markers and therapeutic targets.

MATERIAL AND METHODS

A total of 115 tissue samples (n = 85 NMIBC (pTa, pT1, and CIS) and n = 30 control from BPH patients) were collected. The expression level of autophagy genes (mTOR, ULK1, Beclin1, and LC3) and their proteins were assessed in low and high-grade NMIBC, along with control tissue samples using quantitative real-time polymerase chain reaction and western blotting. Association with clinicopathological characteristics and autophagy gene expression was analyzed by multivariate and univariate survival analysis using SPSS.

RESULT

In high-grade NMIBC, ULK1, P = 0.0150, Beclin1, P = 0.0041, and LC3, P = 0.0014, were substantially downregulated, whereas mTOR, P = 0.0006, was significantly upregulated. The KM plots show significant survival outcomes with autophagy genes. The clinicopathological characters, high grade (P = 0.019), tumor stage (CIS P = 0.039, pT1 P = 0.018, P = 0.045), male (P = 0.010), lymphovascular invasion (P = 0.028) and autophagy genes (ULK1 P = 0.002, beclin1 (P = 0.010, P = 0.022) were associated as risk factors for survival outcome in NMIBC patients.

CONCLUSION

The upregulated mTOR, downregulated ULK1, and beclin1 expression is linked to a high-grade, CIS and pT1 stage, resulting in poor recurrence-free survival and progression-free survival and highlights the prognostic significance of autophagy gene in nonmuscle-invasive bladder cancer.

Autophagy flux in bladder cancer: Cell death crosstalk, drug and nanotherapeutics

Autophagy, a self-digestion mechanism, has emerged as a promising target in the realm of cancer therapy, particularly in bladder cancer (BCa), a urological malignancy characterized by dysregulated biological processes contributing to its progression. This highly conserved catabolic mechanism exhibits aberrant activation in pathological events, prominently featured in human cancers. The nuanced role of autophagy in cancer has been unveiled as a double-edged sword, capable of functioning as both a pro-survival and pro-death mechanism in a context-dependent manner. In BCa, dysregulation of autophagy intertwines with cell death mechanisms, wherein pro-survival autophagy impedes apoptosis and ferroptosis, while pro-death autophagy diminishes tumor cell survival. The impact of autophagy on BCa progression is multifaceted, influencing metastasis rates and engaging with the epithelial-mesenchymal transition (EMT) mechanism. Pharmacological modulation of autophagy emerges as a viable strategy to impede BCa progression and augment cell death. Notably, the introduction of nanoparticles for targeted autophagy regulation holds promise as an innovative approach in BCa suppression. This review underscores the intricate interplay of autophagy with cell death pathways and its therapeutic implications in the nuanced landscape of bladder cancer.

Crosstalk between autophagy and bladder transitional cell carcinoma by autophagy-related lncRNAs

The aim of this study was to investigate the crosstalk between autophagy and bladder transitional cell carcinoma (TCC) by autophagy-related long noncoding RNAs (lncRNAs). A total of 400 TCC patients from The Cancer Genome Atlas were enrolled in this study. We identified the autophagy-related lncRNA expression profile of the TCC patients and then constructed a prognostic signature using the least absolute shrinkage and selection operation and Cox regression. Risk, survival, and independent prognostic analyses were carried out. Receiver operating characteristic curve, nomogram, and calibration curves were explored. Gene Set Enrichment Analysis was employed to verify the enhanced autophagy-related functions. Finally, we compared the signature with several other lncRNA-based signatures. A 9-autophagy-related lncRNA signature was established by least absolute shrinkage and selection operation-Cox regression that was significantly associated with overall survival in TCC. Among them, 8 of the 9 lncRNAs were protective factors while the remaining was a risk factor. The risk scores calculated by the signature showed significant prognostic value in survival analysis between the high- or low-risk groups. The 5-year survival rate for the high-risk group was 26.0% while the rate for the low-risk group was 56.0% (P < .05). Risk score was the only significant risk factor in the multivariate Cox regression survival analysis (P < .001). A nomogram connecting this signature with clinicopathologic characteristics was assembled. To assess the performance of the nomogram, a C-index (0.71) was calculated, which showed great convergence with an ideal model. The Gene Set Enrichment Analysis results demonstrated 2 major autophagy-related pathways were significantly enhanced in TCC. And this signature performed a similar predictive effect as other publications. The crosstalk between autophagy and TCC is significant, and this 9 autophagy-related lncRNA signature is a great predictor of TCC.

Non-coding RNA and autophagy: Finding novel ways to improve the diagnostic management of bladder cancer

Major fraction of the human genome is transcribed in to the RNA but is not translated in to any specific functional protein. These transcribed but not translated RNA molecules are called as non-coding RNA (ncRNA). There are thousands of different non-coding RNAs present inside the cells, each regulating different cellular pathway/pathways. Over the last few decades non-coding RNAs have been found to be involved in various diseases including cancer. Non-coding RNAs are reported to function both as tumor enhancer and/or tumor suppressor in almost each type of cancer. Urothelial carcinoma of the urinary bladder is the second most common urogenital malignancy in the world. Over the last few decades, non-coding RNAs were demonstrated to be linked with bladder cancer progression by modulating different signalling pathways and cellular processes such as autophagy, metastasis, drug resistance and tumor proliferation. Due to the heterogeneity of bladder cancer cells more in-depth molecular characterization is needed to identify new diagnostic and treatment options. This review emphasizes the current findings on non-coding RNAs and their relationship with various oncological processes such as autophagy, and their applicability to the pathophysiology of bladder cancer. This may offer an understanding of evolving non-coding RNA-targeted diagnostic tools and new therapeutic approaches for bladder cancer management in the future.

An Update to Hallmarks of Cancer

In the last decade, there has been remarkable progress in research toward understanding and refining the hallmarks of cancer. In this review, we propose a new hallmark - "pro-survival autophagy." The importance of pro-survival autophagy is well established in tumorigenesis, as it is related to multiple steps in cancer progression and vital for some cancers. Autophagy is a potential anti-cancer therapeutic target. For this reason, autophagy is a good candidate as a new hallmark of cancer. We describe two enabling characteristics that play a major role in enabling cells to acquire the hallmarks of cancer - "tumor-promoting microenvironment and macroenvironment" and "cancer epigenetics, genome instability and mutation." We also discuss the recent updates, therapeutic and prognostic implications of the eight hallmarks of cancer described by Hanahan et al. in 2011. Understanding these hallmarks and enabling characteristics is key not only to developing new ways to treat cancer efficiently but also to exploring options to overcome cancer resistance to treatment.

4-Methoxydalbergione Inhibits Bladder Cancer Cell Growth via Inducing Autophagy and Inhibiting Akt/ERK Signaling Pathway

Bladder cancer (BC) ranks the fourth in incidence in cancers of men and is a common malignant tumor in women. 4-Methoxydalbergione (4MOD), which is purified from Dalbergia sissoo Roxb, has been shown to have anticancer capacity for osteosarcoma and astroglioma. The role of 4MOD in bladder cancer has not been investigated. This study aims to evaluate the anticancer effect of 4MOD in BC cells and its possible mechanisms. The two human bladder cancer cell lines J82 and UMUC3 were used to evaluate the proliferation inhibitory effect of 4MOD by CCK8 and clonogenic assays. The migratory and invasive ability of tumor cells was examined by scratch test and transwell assay. Apoptosis was detected by flow cytometry and TUNEL assays. The autophagy-related molecules including Beclin-1 and LC3 were examined by Western blotting analysis. Furthermore, the RT-PCR was used to detect the mRNA expression of LC3. 4MOD repressed cell proliferation, migration, invasion and induced cell apoptosis in a concentration-dependent manner. The IC₅₀ values of J82 and UMUC3 were 8.17 and 14.50 μM respectively. The mRNA and protein expression ratio of light chain 3-II (LC3-II)/LC3-I and the protein expression of Beclin-1 were increased when the BC cells were treated with 4MOD. The treatment of 4MOD attenuated the phosphorylation of Akt and ERK in the BC cells. We revealed that the 4MOD inhibits BC cells growth by inducing autophagy and inhibiting Akt/ERK signaling pathway. Our study provides new insights into the mechanism by which 4MOD weakens the proliferation of BC cells. This study demonstrates that 4MOD provided a lead compound for the development of novel compound with potent anticancer effect on BC cells.

Autophagy-associated HMGB-1 as a novel potential circulating non-invasive diagnostic marker for detection of Urothelial Carcinoma of Bladder

Urothelial carcinoma of bladder (UBC), a highly prevalent urological malignancy associated with high mortality and recurrence rate. Standard diagnostic method currently being used is cystoscopy but its invasive nature and low sensitivity stresses for identifying predictive diagnostic marker. Autophagy, a cellular homeostasis maintaining process, is usually dysregulated in cancer and its role is still enigmatic in UBC. In this study, 30 UBC patients and healthy controls were enrolled. Histopathologically confirmed tumor and adjacent normal tissue were acquired from patients. Molecular expression and tissue localization of autophagy-associated molecules (HMGB-1, RAGE, beclin, LC-3, and p62) were investigated. Serum HMGB-1 concentration was measured in UBC patients and healthy controls. ROC curves were plotted to evaluate diagnostic potential. Transcript, protein, and IHC expression of HMGB-1, RAGE, beclin, and LC-3 displayed upregulated expression, while p62 was downregulated in bladder tumor tissue. Serum HMGB-1 levels were elevated in UBC patients. Transcript and circulatory levels of HMGB-1 showed positive correlation and displayed a positive trend with disease severity. Upon comparison with clinicopathological parameters, HMGB-1 emerged as molecule of statistical significance to exhibit association. HMGB-1 exhibited optimum sensitivity and specificity in serum. The positive correlation between tissue and serum levels of HMGB-1 showcases serum as a representation of in situ scenario, suggesting its clinical applicability for non-invasive testing. Moreover, optimum sensitivity and specificity displayed by HMGB-1 along with significant association with clinicopathological parameters makes it a potential candidate to be used as diagnostic marker for early detection of UBC but requires further validation in larger cohort.

High Level of Aristolochic Acid Detected With a Unique Genomic Landscape Predicts Early UTUC Onset After Renal Transplantation in Taiwan

Background

The unusual high dialysis prevalence and upper urinary tract urothelial carcinoma (UTUC) incidence in Taiwan may attribute to aristolochic acid (AA), which is nephrotoxic and carcinogenic, exposure. AA can cause a unique mutagenic pattern showing A:T to T:A transversions (mutational Signature 22) analyzed by whole exome sequencing (WES). However, a fast and cost-effective tool is still lacking for clinical practice. To address this issue, we developed an efficient and quantitative platform for the quantitation of AA and tried to link AA detection with clinical outcomes and decipher the genomic landscape of UTUC in Taiwan.

Patients and Methods

We recruited 61 patients with de novo onset of UTUC after kidney transplantation who underwent radical nephroureterectomy. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform was developed for the quantitation of AA. Pearson’s chi-square test, Kaplan–Meier method, and Cox proportional hazard model were utilized to assess the correlations among AA detection, clinicopathological characteristics, and clinical outcomes. Seven tumors and seven paired normal tissues were sequenced using WES (approximately 800x sequencing depth) and analyzed by bioinformatic tool.

Results

We found that high level of 7-(deoxyadenosin-N⁶-yl)aristolactam I (dA-AL-I) detected in paired normal tissues was significantly correlated with fast UTUC initiation times after renal transplantation (p = 0.035) and with no use of sirolimus (p = 0.046). Using WES analysis, we further observed that all tumor samples were featured by Signature 22 mutations, apolipoprotein B mRNA-editing enzyme, catalytic polypeptide (APOBEC)-associated gene mutations, p53 mutations, no fibroblast growth factor receptor 3 (FGFR3) mutation, and high tumor mutation burden (TMB). Especially, mammalian target of rapamycin (mTOR) activation predominated in dA-AL-I-detected samples compared with those without dA-AL-I detection and might be associated with UTUC initiation through cell proliferation and suppression of UTUC progression via autophagy inhibition.

Conclusion

Accordingly, dA-AL-I detection can provide more direct evidence to AA exposure and serve as a more specific predictive and prognostic biomarker for patients with de novo onset of UTUC after kidney transplantation.

Starvation induced autophagy promotes the progression of bladder cancer by LDHA mediated metabolic reprogramming

Background

Aberrant autophagy and preternatural elevated glycolysis are prevalent in bladder cancer (BLCA) and are both related to malignant progression. However, the regulatory relationship between autophagy and glycolytic metabolism remains largely unknown. We imitated starvation conditions in the tumour microenvironment and found significantly increased levels of autophagy and aerobic glycolysis, which both regulated the progression of BLCA cells. We further explored the regulatory relationships and mechanisms between them.

Methods

We used immunoblotting, immunofluorescence and transmission electron microscopy to detect autophagy levels in BLCA cells under different treatments. Lactate and glucose concentration detection demonstrated changes in glycolysis. The expression of lactate dehydrogenase A (LDHA) was detected at the transcriptional and translational levels and was also silenced by small interfering RNA, and the effects on malignant progression were further tested. The underlying mechanisms of signalling pathways were evaluated by western blot, immunofluorescence and immunoprecipitation assays.

Results

Starvation induced autophagy, regulated glycolysis by upregulating the expression of LDHA and caused progressive changes in BLCA cells. Mechanistically, after starvation, the ubiquitination modification of Axin1 increased, and Axin1 combined with P62 was further degraded by the autophagy–lysosome pathway. Liberated β-catenin nuclear translocation increased, binding with LEF1/TCF4 and promoting LDHA transcriptional expression. Additionally, high expression of LDHA was observed in cancer tissues and was positively related to progression.

Conclusion

Our study demonstrated that starvation-induced autophagy modulates glucose metabolic reprogramming by enhancing Axin1 degradation and β-catenin nuclear translocation in BLCA, which promotes the transcriptional expression of LDHA and further malignant progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02303-1.

Emerging roles of autophagy in the development and treatment of urothelial carcinoma of the bladder

INTRODUCTION

High recurrence rates, frequent surveillance strategies, and current multidisciplinary treatment approaches make urothelial carcinoma of bladder (UCB) one of the most expensive cancers to clinically manage. Recent studies have demonstrated a role for autophagy in bladder tumorigenesis. It serves as a tumor suppressor by maintaining genomic integrity and preventing tumor proliferation during initial stages of tumor development. Nevertheless, once established, cancer cells may utilize protective autophagy to endure cellular stress and survive in the adverse environment. Its excessive stimulation supports cancer cells' resistance to therapeutic modalities.

AREAS COVERED

PubMed and Google Scholar electronic databases were searched for recently published studies. This review summarizes emerging roles of autophagy in development/progression of UCB and treatment resistance and explores novel therapeutic targets for prevention of cancer invasion, metastatic spread', and disease relapse.

EXPERT OPINION

The development of novel therapies via targeting of autophagy may augment current treatment regimens and improve clinical outcomes. Synthetic compounds or plant-based metabolites are reported to enhance cancer therapies by modulating autophagic flux. Successful autophagy-focused therapeutic intervention requires a mechanistic understanding of autophagic effects on tumor initiation and progression and the development of efficient biomarkers to monitor it in tumor tissues.

Cancer-Associated Fibroblasts Regulate Bladder Cancer Invasion and Metabolic Phenotypes through Autophagy

Recently, both cancer-associated fibroblasts (CAFs) and autophagy have been proven to play an important role in tumor development, including bladder cancer (BCa). However, the real mechanisms remain largely unclear. Here, we reconstruct a mimic tumor microenvironment to explore the interaction between CAFs and the BCa cell line T24 using a coculture system. Autophagy in CAFs was induced or inhibited by rapamycin or siRNA, respectively. After coculture with CAFs, T24 cell proliferation, invasion, and aerobic glycolysis were tested in vitro. Rapamycin induced and siAtg5 inhibited autophagy in CAFs. Enhanced autophagy in CAFs promoted cell proliferation and invasion in T24 cells in vitro, while there was no significant difference between the autophagy-inhibited group and the controls. Lactate concentration was elevated in both rapamycin-treated and siAtg5-treated groups compared with the control group. In addition, the expression levels of MCT1, MCT4, HK2, SLC2A1, and MMP-9 were all increased in T24 cells in the autophagy-enhanced group. Our results indicated that CAFs could regulate BCa invasion and metabolic phenotypes through autophagy, providing us with new alternative treatments for BCa in the future.

Identification of autophagy-related genes signature predicts chemotherapeutic and immunotherapeutic efficiency in bladder cancer (BLCA)

Autophagy maintains cellular homeostasis by degrading and recycling cytoplasmic components under stress conditions, which is identified to be involved in tumorigenesis and now has been recognized as novel target in cancer treatment. In present study, we gathered total autophagy‐related genes and established an autophagy‐related genes signature (ATGRS) through LASSO cox regression analysis in BLCA. Kaplan‐Meier survival and multivariate cox regression analyses both showed the ATGRS was a robust independent prognostic factor with high accuracy. Subsequently, integrated analyses indicated that ATGRS had a strong correlation with molecular subtypes, clinicopathological characteristics and somatic mutation alteration. Moreover, ATGRS was found to be positively correlated with the infiltration of immune cells in tumour microenvironment (TME) and immune checkpoint expression, indicating the potent role of autophagy by regulating the TME. In addition, ATGRS was proved to be efficient in predicting the clinical benefit of immune checkpoint inhibitors (ICIs) based immunotherapy and chemotherapy in BLCA. Furthermore, we observed abnormal expression levels of autophagy‐related genes and found the different behaviour of ATGRS in pancancer by LASSO cox regression analysis. Therefore, construction of ATGRS in BLCA could help us to interpret the underlying mechanism of autophagy and sheds a light on the clinical application for a combination of autophagy modification with targeted immunotherapy and chemotherapy in BLCA.

Prodigiosin Sensitizes Sensitive and Resistant Urothelial Carcinoma Cells to Cisplatin Treatment

Cisplatin-based treatment is the standard of care therapy for urothelial carcinomas. However, complex cisplatin resistance mechanisms limit the success of this approach. Both apoptosis and autophagy have been shown to contribute to this resistance. Prodigiosin, a secondary metabolite from various bacteria, exerts different biological activities including the modulation of these two cellular stress response pathways. We analyzed the effect of prodigiosin on protein levels of different autophagy- and apoptosis-related proteins in cisplatin-sensitive and -resistant urothelial carcinoma cells (UCCs). Furthermore, we investigated the effect on cell viability of prodigiosin alone or in combination with cisplatin. We made use of four different pairs of cisplatin-sensitive and -resistant UCCs. We found that prodigiosin blocked autophagy in UCCs and re-sensitized cisplatin-resistant cells to apoptotic cell death. Furthermore, we found that prodigiosin is a potent anticancer agent with nanomolar IC50 values in all tested UCCs. In combination studies, we observed that prodigiosin sensitized both cisplatin-sensitive and -resistant urothelial carcinoma cell lines to cisplatin treatment with synergistic effects in most tested cell lines. These effects of prodigiosin are at least partially mediated by altering lysosomal function, since we detected reduced activities of cathepsin B and L. We propose that prodigiosin is a promising candidate for the therapy of cisplatin-resistant urothelial carcinomas, either as a single agent or in combinatory therapeutic approaches.

Inhibition of autophagy by 3-methyladenine restricts murine cytomegalovirus replication

Cytomegalovirus (CMV) induced autophagy affects virus replication and survival of the infected cells. The purpose of this study was to investigate the role of autophagy inhibition by 3-methyladenine (3-MA) on murine cytomegalovirus (MCMV) replication and whether it is associated with caspase-3 dependent apoptosis. The eyecup isolated from adult C57BL/6J mice (6-8 weeks old) and mouse embryo fibroblast cells (MEFs) were infected with MCMV K181 strain, followed by the treatment of 3-methyladenine (3-MA), chloroquine, or rapamycin to block or stimulate autophagy. In cultured MEFs, the ratio of LC3I/II was reduced at 24 hours post infection (hpi), but was increased at 48 hpi In the eyecup culture, LC3I/II ratio was also decreased at 4 and 7 days post infection (dpi). In addition, caspase-3 cleavage was increased at 48 hpi in MEFs and also elevated in MCMV infected eyecups at 4, 7, 10, and 14 dpi. 3-MA treatment significantly inhibited the virus replication in MEFs and eyecups. The expression of early antigen (EA) of MCMV was also decreased in MEFs and eyecups. Meanwhile, cleaved caspase-3 dependent cell death was promoted with the presence of 3-MA in MCMV infected MEFs and eyecups, while RIPK1/RIPK3/MLKL pathway was inhibited by 3-MA in eyecups. Inhibition of autophagy by 3-MA restricts virus replication and promotes caspase-3 dependent apoptosis in the eyecup and MEFs with MCMV infection. It can be explained that during the early period of MCMV infection, the suppressed autophagy process directly reduced virus release, but later caspase-3 dependent apoptosis dominated and resulted in decreased virus replication.

Autophagy modulating agents as chemosensitizers for cisplatin therapy in cancer

Although cisplatin is one of the most common antineoplastic drug, its successful utilisation in cancer treatment is limited by the drug resistance. Multiple attempts have been made to find potential cisplatin chemosensitisers which would overcome cancer cells resistance thus improving antineoplastic efficacy. Autophagy modulation has become an important area of interest regarding the aforementioned topic. Autophagy is a highly conservative cellular self-digestive process implicated in response to multiple environmental stressors. The high basal level of autophagy is a common phenomenon in cisplatin-resistant cancer cells which is thought to grant survival benefit. However current evidence supports the role of autophagy in either promoting or limiting carcinogenesis depending on the context. This encourages the search of substances modulating the process to alleviate cisplatin resistance. Such a strategy encompasses not only simple autophagy inhibition but also harnessing the process to induce autophagy-dependent cell death. In this paper, we briefly describe the mechanism of cisplatin resistance with a special emphasis on autophagy and we give an extensive literature review of potential substances with cisplatin chemosensitising properties related to autophagy modulation.

Contrast effects of autophagy in the treatment of bladder cancer

Bladder cancer is a disease that negatively affects patients' quality of life, but treatment options have remained unchanged for a long time. Although promising results have been achieved with current bladder cancer treatments, cancer recurrence, progression, and therapy resistance are the most severe problems preventing the efficiency of bladder cancer treatments. Autophagy refers to an evolutionarily conserved catabolic process in which proteins, damaged organelles, and cytoplasmic components are degraded by lysosomal enzymes. Autophagy regulates the therapeutic response to the chemotherapy drugs, thus determining the effect of therapy on cancer cells. Autophagy is a stress-induced cell survival mechanism and its excessive stimulation can cause resistance of tumor cells to therapeutic agents. Depending on the conditions, an increase in autophagy may cause treatment resistance or autophagic cell death, and it is related to important anti-cancer mechanisms, such as apoptosis. Therefore, understanding the roles of autophagy under different conditions is important for designing effective anti-cancer agents. The dual role of autophagy in cancer has attracted considerable attention in respect of bladder cancer treatment. In this review, we summarize the basic characteristics of autophagy, including its mechanisms, regulation, and functions, and we present examples from current studies concerning the dual role of autophagy in bladder cancer progression and therapy.

Oblongifolin C reverses GEM resistance via suppressing autophagy flux in bladder cancer cells

A number of previous studies have demonstrated that inhibiting autophagy can increase the cellular cytotoxicity of chemotherapeutic agents in urothelial cancer cells. However, the mechanistic roles of autophagy in gemcitabine (GEM) resistant bladder cancer cells have not been thoroughly investigated. In the present study, immunohistochemistry staining of autophagy marker LC3 was performed in bladder cancer and healthy control tissues and demonstrated an essential role of autophagy in cancer development. A GEM-resistant cell line was established to assess the effects of autophagy on the acquisition of GEM resistance. Western blotting of autophagy markers in GEM-resistant bladder cancer cells suggested that GEM resistance was caused, at least partially, by GEM-induced autophagy. GEM resistance was demonstrated to be reversed by the inhibition of autophagy by 3-methyladenine. In addition, oblongifolin C (OC), a novel autophagic flux inhibitor purified from traditional Chinese medicine, was found to enhance the efficiency of GEM in GEM-resistant bladder cancer cells by inhibiting autophagic flux. In conclusion, data from the present study suggest that autophagy serves an important role in bladder cancer development and GEM resistance. OC treatment has the ability to reverse GEM-resistance in bladder cancer cells by suppressing autophagic flux, thereby providing a potential adjunctive therapeutic option for bladder cancer GEM treatment.

Nr1d1 affects autophagy in the skeletal muscles of juvenile Nile tilapia by regulating the rhythmic expression of autophagy-related genes

Autophagy is an important evolutionary conserved process in eukaryotic organisms for the turnover of intracellular substances. Recent studies revealed that autophagy displays circadian rhythms in mice and zebrafish. To date, there is no report focused on the rhythmic changes of autophagy in fish skeletal muscles upon nutritional deprivation. In this study, we examined the circadian rhythms of 158 functional genes in tilapia muscle in response to starvation. We found that 12 genes were involved in autophagy changed their rhythm after starvation. Among these genes, Atg4c, Bnip3la, Lc3a, Lc3b, Lc3c, and Ulk1a exhibited a daily rhythmicity in tilapia muscle, and Atg4b, becn1, bnip3la, bnip3lb, Lc3a, and ulk1b were significantly upregulated in response to starvation. The number of autophagosomes was dramatically increased in fasted fish, indicating that nutritional signals affect not only the muscular clock system but also its autophagy behavior. Administration of GSK4112, an activator of Nr1d1, altered rhythmic expression of both circadian clock genes and autophagy genes in tilapia muscle. Taken together, these findings provide evidence that nutritional deficiency affects both circadian regulation and autophagy activities in skeletal muscle.

Emerging Roles of Cancer Stem Cells in Bladder Cancer Progression, Tumorigenesis, and Resistance to Chemotherapy: A Potential Therapeutic Target for Bladder Cancer

Bladder cancer (BC) is a complex and highly heterogeneous stem cell disease associated with high morbidity and mortality rates if it is not treated properly. Early diagnosis with personalized therapy and regular follow-up are the keys to a successful outcome. Cancer stem cells (CSCs) are the leading power behind tumor growth, with the ability of self-renewal, metastasis, and resistance to conventional chemotherapy. The fast-developing CSC field with robust genome-wide screening methods has found a platform for establishing more reliable therapies to target tumor-initiating cell populations. However, the high heterogeneity of the CSCs in BC disease remains a large issue. Therefore, in the present review, we discuss the various types of bladder CSC heterogeneity, important regulatory pathways, roles in tumor progression and tumorigenesis, and the experimental culture models. Finally, we describe the current stem cell-based therapies for BC disease.

Up-regulation of DRAM2 promotes tolerance of bladder transitional cell carcinoma to gemcitabine

INTRODUCTION

Bladder transitional cell carcinoma (BTCC) is one of the most prevalent human malignant diseases. Gemcitabine is commonly applied in the treatment of BTCC while acquired gemcitabine resistance has caused a severe impediment to recovery. This study aimed to investigate the function of DRAM2 in regulating gemcitabine resistance of BTCC.

MATERIAL AND METHODS

GSE77883 was introduced to screen out the differentially expressed autophagy-related genes in T24 cells and gemcitabine-resistant T24-GEM cells. After establishing T24-GEM cells ourselves, aberrant expression of DRAM2 was detected by qRT-PCR and Western blot. After stably manipulating the expression of DRAM2 in T24 and T24-GEM cells, the changes of cell biological functions under gemcitabine treatment were compared, including cell viability, apoptosis and autophagy, using colony formation, flow cytometry and electron microscopy respectively.

RESULTS

DRAM2 was up-regulated in gemcitabine-resistant T24-GEM cells. Silencing of DRAM2 in T24-GEM cells inhibited the cell autophagy induced by treatment with gemcitabine and contributed to attenuated gemcitabine resistance. Also, overexpression of DRAM2 in T24 cells enhanced the autophagy, strengthened the chemoresistance and decreased the cell apoptosis rate under the treatment with gemcitabine.

CONCLUSIONS

Our data suggested that downregulation of DRAM2 rescued the sensitivity of T24-GEM cells to gemcitabine, providing an appropriate therapeutic target for BTCC treatment.

Pro-survival autophagy: An emerging candidate of tumor progression through maintaining hallmarks of cancer

Autophagy is an evolutionary conserved catabolic process that regulates the cellular homeostasis by targeting damaged cellular contents and organelles for lysosomal degradation and sustains genomic integrity, cellular metabolism, and cell survival during diverse stress and adverse conditions. Recently, the role of autophagy is extremely debated in the regulation of cancer initiation and progression. Although autophagy has a dichotomous role in the regulation of cancer, growing numbers of studies largely indicate the pro-survival role of autophagy in cancer progression and metastasis. In this review, we discuss the detailed mechanisms of autophagy, the role of pro-survival autophagy that positively drives several classical as well as emerging hallmarks of cancer for tumorigenic progression, and also we address various autophagy inhibitors that could be harnessed against pro-survival autophagy for effective cancer therapeutics. Finally, we highlight some outstanding problems that need to be deciphered extensively in the future to unravel the role of autophagy in tumor progression.

CDK5RAP3 Participates in Autophagy Regulation and Is Downregulated in Renal Cancer

Renal cancer is one of the most common malignant urological tumors; however, its diagnosis and treatment are not well established. In the present study, we identified that CDK5 regulatory subunit-associated protein 3 (CDK5RAP3), a putative tumor suppressor in many cancers, was downregulated in renal cancer tissues. Through loss- and gain-of-function experiments, we observed that the action of CDK5RAP3 in renal cancer cells was different in Caki-1 and 769-P cell lines. Knockdown of endogenous CDK5RAP3 in Caki-1 slightly increased cell viability, whereas overexpression of CDK5RAP3 in 769-P cells inhibited cell viability. In addition, we observed that CDK5RAP3 participated in the regulation of autophagy in renal cancer. Knockdown of CDK5RAP3 induced significant inhibition of autophagy in Caki-1 cells but not in 769-P cells. In contrast, overexpression of CDK5RAP3 significantly activated autophagy in 769-P cells, as evidenced by increased LC3-II levels. However, the LC3-II could not be altered by CDK5RAP3 overexpression in Caki-1 cells. These findings demonstrated that CDK5RAP3 is downregulated in renal cancer and may be associated with autophagy.

Stem-Like Signature Predicting Disease Progression in Early Stage Bladder Cancer. The Role of E2F3 and SOX4

The rapid development of the cancer stem cells (CSC) field, together with powerful genome-wide screening techniques, have provided the basis for the development of future alternative and reliable therapies aimed at targeting tumor-initiating cell populations. Urothelial bladder cancer stem cells (BCSCs) that were identified for the first time in 2009 are heterogenous and originate from multiple cell types; including urothelial stem cells and differentiated cell types—basal, intermediate stratum and umbrella cells Some studies hypothesize that BCSCs do not necessarily arise from normal stem cells but might derive from differentiated progenies following mutational insults and acquisition of tumorigenic properties. Conversely, there is data that normal bladder tissues can generate CSCs through mutations. Prognostic risk stratification by identification of predictive markers is of major importance in the management of urothelial cell carcinoma (UCC) patients. Several stem cell markers have been linked to recurrence or progression. The CD44v8-10 to standard CD44-ratio (total ratio of all CD44 alternative splicing isoforms) in urothelial cancer has been shown to be closely associated with tumor progression and aggressiveness. ALDH1, has also been reported to be associated with BCSCs and a worse prognosis in a large number of studies. UCC include low-grade and high-grade non-muscle invasive bladder cancer (NMIBC) and high-grade muscle invasive bladder cancer (MIBC). Important genetic defects characterize the distinct pathways in each one of the stages and probably grades. As an example, amplification of chromosome 6p22 is one of the most frequent changes seen in MIBC and might act as an early event in tumor progression. Interestingly, among NMIBC there is a much higher rate of amplification in high-grade NMIBC compared to low grade NMIBC. CDKAL1, E2F3 and SOX4 are highly expressed in patients with the chromosomal 6p22 amplification aside from other six well known genes (ID4, MBOAT1, LINC00340, PRL, and HDGFL1). Based on that, SOX4, E2F3 or 6q22.3 amplifications might represent potential targets in this tumor type. Focusing more in SOX4, it seems to exert its critical regulatory functions upstream of the Snail, Zeb, and Twist family of transcriptional inducers of EMT (epithelial–mesenchymal transition), but without directly affecting their expression as seen in several cell lines of the Cancer Cell Line Encyclopedia (CCLE) project. SOX4 gene expression correlates with advanced cancer stages and poor survival rate in bladder cancer, supporting a potential role as a regulator of the bladder CSC properties. SOX4 might serve as a biomarker of the aggressive phenotype, also underlying progression from NMIBC to MIBC. The amplicon in chromosome 6 contains SOX4 and E2F3 and is frequently found amplified in bladder cancer. These genes/amplicons might be a potential target for therapy. As an existing hypothesis is that chromatin deregulation through enhancers or super-enhancers might be the underlying mechanism responsible of this deregulation, a potential way to target these transcription factors could be through epigenetic modifiers.

Blocking mutation independent p53 aggregation by emodin modulates autophagic cell death pathway in lung cancer

Loss of p53 function via mutation is a very common cause of human cancers. Recent studies have provided evidence on presence of self aggregated p53 in cancer cells leading to its altered functions towards cause of cancer. The general notion has been that mutated p53 exposes adhesive sites that promote self aggregation, however a complete mechanistic understanding to this has been lacking. We embarked on the present study towards exploring the differential aggregation pattern in cells expressing mutated TP53 (HaCaT keratinocytes) vs those expressing the wild type copy of the p53 protein (A549 lung cancer cell line). The studies led us to interesting observation that formation of p53 protein aggregates is not always associated with TP53 mutation. The A549 lung cancer cells, having wild type TP53, showed the appearance of p53 protein aggregates, while no protein aggregates were observed in normal HaCaT keratinocytes carrying mutant TP53. We went on to study the effect of blocking protein aggregation by emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) and figured that inhibiting p53 protein aggregation can elevate the level of autophagy in A549 lung cancer cell line while there is no significant effect on autophagy in normal non-cancerous HaCaT cells. Moreover, ATG5 was found to be coaggregated with p53 aggregates which dissociated after emodin treatment, indicating further induction of autophagy in A549 cells only. From these observations, we conclude that the increased level of autophagy might be the mechanism for the removal of p53 protein aggregates which restores p53 function in A549 cells after emodin treatment .This encourages further studies towards deciphering related mechanistic aspects vis-à-vis potential therapeutic strategies against cancer.

Cell death-based approaches in treatment of the urinary tract-associated diseases: a fight for survival in the killing fields

Urinary tract-associated diseases comprise a complex set of disorders with a variety of etiologic agents and therapeutic approaches and a huge global burden of disease, estimated at around 1 million deaths per year. These diseases include cancer (mainly prostate, renal, and bladder), urinary tract infections, and urolithiasis. Cell death plays a key role in the pathogenesis and therapy of these conditions. During urinary tract infections, invading bacteria may either promote or prevent host cell death by interfering with cell death pathways. This has been studied in detail for uropathogenic E. coli (UPEC). Inhibition of host cell death may allow intracellular persistence of live bacteria, while promoting host cell death causes tissue damage and releases the microbes. Both crystals and urinary tract obstruction lead to tubular cell death and kidney injury. Among the pathomechanisms, apoptosis, necroptosis, and autophagy represent key processes. With respect to malignant disorders, traditional therapeutic efforts have focused on directly promoting cancer cell death. This may exploit tumor-specific characteristics, such as targeting Vascular Endothelial Growth Factor (VEGF) signaling and mammalian Target of Rapamycin (mTOR) activity in renal cancer and inducing survival factor deprivation by targeting androgen signaling in prostate cancer. An area of intense research is the use of immune checkpoint inhibitors, aiming at unleashing the full potential of immune cells to kill cancer cells. In the future, this may be combined with additional approaches exploiting intrinsic sensitivities to specific modes of cell death such as necroptosis and ferroptosis. Here, we review the contribution of diverse cell death mechanisms to the pathogenesis of urinary tract-associated diseases as well as the potential for novel therapeutic approaches based on an improved molecular understanding of these mechanisms.

Targeting urothelial carcinoma cells by combining cisplatin with a specific inhibitor of the autophagy-inducing class III PtdIns3K complex

BACKGROUND

Cisplatin-based regimens are routinely employed for the treatment of urothelial carcinoma. However, therapeutic success is hampered by the primary presence of or the development of cisplatin resistance. This chemoresistance is executed by multiple cellular pathways. In recent years, the cellular process of autophagy has been identified as a prosurvival pathway of cancer cells. On the one hand, autophagy enables cancer cells to survive conditions of low oxygen or nutrient supply, frequently found in tumors. On the other hand, autophagy supports chemoresistance of cancer cells. Here, we aimed at investigating the involvement of autophagy for cisplatin resistance in different urothelial carcinoma cell lines.

MATERIALS & METHODS

We analyzed the expression levels of different autophagy-related proteins in cisplatin-sensitive and cisplatin-resistant urothelial carcinoma cell lines. Furthermore, we performed cell viability assays and caspase activity assays with cells treated with cisplatin, non-specific or specific autophagy inhibitors (chloroquine, 3-methyladenine, SAR405) or combinations thereof.

RESULTS

We found that autophagy-related proteins are up-regulated in different cisplatin-resistant urothelial carcinoma cells compared to the sensitive parental cell lines. Furthermore, inhibition of autophagy, in general, or of the autophagy-inducing class III PtdIns3K complex, in particular, sensitized both sensitive and resistant urothelial carcinoma cells to cisplatin-induced cytotoxic effects.

CONCLUSION

We propose that targeting the autophagic machinery might represent a suitable approach to complement or even increase cisplatin efficacy in order to overcome cisplatin resistance in urothelial carcinoma.

Dual Inhibition of PIK3C3 and FGFR as a New Therapeutic Approach to Treat Bladder Cancer

Purpose: MPT0L145 has been developed as a FGFR inhibitor exhibiting significant anti-bladder cancer activity in vitro and in vivo via promoting autophagy-dependent cell death. Here, we aim to elucidate the underlying mechanisms.Experimental Design: Autophagy flux, morphology, and intracellular organelles were evaluated by Western blotting, transmission electron microscope, and fluorescence microscope. Molecular docking and surface plasmon resonance assay were performed to identify drug-protein interaction. Lentiviral delivery of cDNA or shRNA and CRISPR/Cas9-mediated genome editing was used to modulate gene expression. Mitochondrial oxygen consumption rate was measured by a Seahorse XFe24 extracellular flux analyzer, and ROS level was measured by flow cytometry.Results: MPT0L145 persistently increased incomplete autophagy and phase-lucent vacuoles at the perinuclear region, which were identified as enlarged and alkalinized late-endosomes. Screening of a panel of lipid kinases revealed that MPT0L145 strongly inhibits PIK3C3 with a K_d value of 0.53 nmol/L. Ectopic expression of PIK3C3 reversed MPT0L145-increased cell death and incomplete autophagy. Four residues (Y670, F684, I760, D761) at the ATP-binding site of PIK3C3 are important for the binding of MPT0L145. In addition, MPT0L145 promotes mitochondrial dysfunction, ROS production, and DNA damage, which may in part, contribute to cell death. ATG5-knockout rescued MPT0L145-induced cell death, suggesting simultaneous induction of autophagy is crucial to its anticancer activity. Finally, our data demonstrated that MPT0L145 is able to overcome cisplatin resistance in bladder cancer cells.Conclusions: MPT0L145 is a first-in-class PIK3C3/FGFR inhibitor, providing an innovative strategy to design new compounds that increase autophagy, but simultaneously perturb its process to promote bladder cancer cell death. Clin Cancer Res; 24(5); 1176-89. ©2017 AACR.

Cancer stem cells and epithelial-mesenchymal transition in urothelial carcinoma: Possible pathways and potential therapeutic approaches

There is growing evidence of the presence of cancer stem cells in urothelial carcinoma. Cancer stem cells have the ability to self-renew and to differentiate into all cell types of the original heterogeneous tumor. A panel of diverse cancer stem cell markers might be suitable for simulation studies of urothelial cancer stem cells and for the development of optimized treatment protocols. The present review focuses on the advances in recognizing the markers of urothelial cancer stem cells and possible therapeutic targets. The commonly reported markers and pathways that were evaluated include CD44, CD133, ALDH1, SOX2 & SOX4, BMI1, EZH1, PD-L1, MAGE-A3, COX2/PGE2/STAT3, AR, and autophagy. Studies on the epithelial-mesenchymal transition-related pathways (Shh, Wnt/β-catenin, Notch, PI3K/Akt, TGF-β, miRNA) are also reviewed. Most of these markers were recognized through the expression patterns of cancer stem cell-rich side populations. Their regulative role in the development and differentiation of urothelial cancer stem cells was confirmed in vitro by functional analyses (e.g. cell migration, colony formation, sphere formation), and in vivo in xenograft experiments. Although a small number of these pathways are targeted by currently available drugs or drugs that are the currently being tested in clinical trials, a clear treatment approach has not been developed for most pathways. A greater understanding of the mechanisms that control the proliferation and differentiation of cancer stem cells is expected to lead to improvements in targeted therapy.

Frondoside A induces AIF-associated caspase-independent apoptosis in Burkitt lymphoma cells

For patients with refractory or relapsed Burkitt lymphoma (BL), no standard therapy is available for second-line treatment to date. Nonfunctional caspases-dependent apoptosis pathways, inactivating p53 mutations and pro-survival autophagy prevent activity of conventional chemotherapy. Thus, new drugs bypassing these mechanisms of resistance are required. Here, we investigated the efficacy of the marine natural compound frondoside A (FrA) in eight BL cell lines. FrA revealed cytotoxic effects in all cell lines tested including the multiresistant CA46 cells. Remarkably, FrA induced caspases- and p53-independent apoptosis, which was characterized by decreased expression of antiapoptotic survivin and Bcl-2, mitochondria targeting (release of cytochrome C, HtrA2/Omi and the apoptosis-inducing factor (AIF), and altered production of ROS) and translocation of AIF to the nuclei. In addition, signs of inhibition of pro-survival autophagy were observed. Thus, FrA is a promising candidate for the treatment of refractory or relapsed BL revealing resistances to standard therapies.

Chloroquine and hydroxychloroquine inhibit bladder cancer cell growth by targeting basal autophagy and enhancing apoptosis

Chloroquine (CQ) and hydroxychloroquine (HCQ), two antimalarial drugs, are suggested to have potential anticancer properties. in the present study, we investigated the effects of CQ and HCQ on cell growth of bladder cancer with emphasis on autophagy inhibition and apoptosis induction in vitro. The results showed that CQ and HCQ inhibited the proliferation of multiple human bladder cell lines (including RT4, 5637, and T24) in a time- and dose-dependent fashion, especially in advanced bladder cancer cell lines (5637 and T24) compared to immortalized uroepithelial cells (SV-Huc-1) or other reference cancer cell lines (PC3 and MCF-7). We found that 24-hour treatment of CQ or HCQ significantly decreased the clonogenic formation in 5637 and T24 cells compared to SV-Huc-1. As human bladder cancer tumor exhibits high basal level of autophagic activities, we detected the autophagic flux in cells treated with CQ and HCQ, showing an alternation in LC3 flux in CQ- or HCQ-treated cells. Moreover, bladder cancer cells treated with CQ and HCQ underwent apoptosis, resulting in increased caspase 3/7 activities, increased level of cleaved poly(ADP-ribose) polymerase (PARP), caspase 3, and DNA fragmentation. Given these results, targeting autophagy with CQ and HCQ represents an effective cancer therapeutic strategy against human bladder cancer.

The marine triterpene glycoside frondoside A induces p53-independent apoptosis and inhibits autophagy in urothelial carcinoma cells

Background

Advanced urothelial carcinomas represent a considerable clinical challenge as they are difficult to treat. Platinum-based combination regimens obtain response rates ranging from 40 to 70% in first-line therapy of advanced urothelial carcinoma. In the majority of cases, however, the duration of these responses is limited, and when progression occurs, the outcome is generally poor. Therefore, novel therapeutic strategies are urgently needed. The purpose of the current research is to investigate the anticancer effects and the mode of action of the marine triterpene glycoside frondoside A in p53-wild type and p53-deficient human urothelial carcinoma cells.

Methods

Activity of frondoside A was examined in the human urothelial carcinoma cell lines RT112, RT4, HT-1197, TCC-SUP, T-24, and 486p. Effects of frondoside A on cell viability, either alone or in combination with standard cytotoxic agents were investigated, and synergistic effects were analyzed. Pro-apoptotic activity was assessed by Western blotting and FACS, alone and in combination with a caspases-inhibitor. The impact of functional p53 was investigated by siRNA gene silencing and the p53 inhibitor pifithrin-α. Effects on autophagy were studied using LC3B-I/II and SQSTM/p62 as markers. The unpaired Student’s t-test was used for comparison of the data sets.

Results

Frondoside A shows high cytotoxicity in urothelial carcinoma cells with IC_50s ranging from 0.55 to 2.33 μM while higher concentrations of cisplatin are required for comparable effects (IC₅₀ = 2.03 ~ 5.88 μM). Induction of apoptosis by frondoside A was associated with the regulation of several pro-apoptotic factors, like caspase-3, -8, and -9, PARP, Bax, p21, DNA fragmentation, and externalization of phosphatidylserine. Remarkably, inhibition of p53 by gene silencing or pifithrin-α pretreatment, as well as caspase inhibition, did not suppress apoptotic activity of frondoside A, while cisplatin activity, in contrast, was significantly decreased. Frondoside A inhibited pro-survival autophagy, a known mechanism of drug resistance in urothelial carcinoma and showed synergistic activity with cisplatin and gemcitabine.

Conclusions

A unique combination of properties makes marine compound frondoside A a promising candidate for the treatment of human urothelial carcinomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3085-z) contains supplementary material, which is available to authorized users.

Functional inhibition of Hsp70 by Pifithrin-μ switches Gambogic acid induced caspase dependent cell death to caspase independent cell death in human bladder cancer cells

Heat shock protein-70kDa (Hsp70) is a member of molecular chaperone family, involved in the proper folding of various proteins. Hsp70 is important for tumor cell survival and is also reported to be involved in enhancing the drug resistance of various cancer types. Hsp70 controls apoptosis both upstream and downstream of the mitochondria by regulating the mitochondrial membrane permeabilization (MMP) and apoptosome formation respectively. In the present study, we have elucidated the role of Hsp70 in Gambogic acid (GA) induced apoptosis in bladder cancer cells. We observed that functional inhibition of Hsp70 by Pifithrin-μ switches GA induced caspase dependent (apoptotic) cell death to caspase independent cell death. However, this cell death was not essentially necrotic in nature, as shown by the observations like intact plasma membranes, cytochrome-c release and no significant effect on nuclear condensation/fragmentation. Inhibition of Hsp70 by Pifithrin-μ shows differential effect on MMP. GA induced MMP and cytochrome-c release was inhibited by Pifithrin-μ at 12h but enhanced at 24h. Pifithrin-μ also reverted back GA inhibited autophagy which resulted in the degradation of accumulated ubiquitinated proteins. Our results demonstrate that Hsp70 plays an important role in GA induced apoptosis by regulating caspase activation. Therefore, inhibition of Hsp70 may hamper with the caspase dependent apoptotic pathways induced by most anti-cancer drugs and reduce their efficacy. However, the combination therapy with Pifithrin-μ may be particularly useful in targeting apoptotic resistant cancer cells as Pifithrin-μ may initiate alternative cell death program in these resistant cells.

Autophagy and urothelial carcinoma of the bladder: A review

The incidence of urothelial carcinoma of the urinary bladder (bladder cancer) remains high. While other solid organ malignancies have seen significant improvement in morbidity and mortality, there has been little change in bladder cancer mortality in the past few decades. The mortality is mainly driven by muscle invasive bladder cancer, but the cancer burden remains high even in nonmuscle invasive bladder cancer due to high recurrence rates and risk of progression. While apoptosis deregulation has long been an established pathway for cancer progression, nonapoptotic pathways have gained prominence of late. Recent research in the role of autophagy in other malignancies, including its role in treatment resistance, has led to greater interest in the role of autophagy in bladder cancer. Herein, we summarize the literature regarding the role of autophagy in bladder cancer progression and treatment resistance. We address it by systematically reviewing treatment modalities for nonmuscle invasive and muscle invasive bladder cancer.

Clinical relevance of autophagic therapy in cancer: Investigating the current trends, challenges, and future prospects

Oncophagy (cancer-related autophagy) has a complex dual character at different stages of tumor progression. It remains an important clinical problem to unravel the reasons that propel the shift in the role of oncophagy from tumor inhibition to a protective mechanism that shields full-blown malignancy. Most treatment strategies emphasize curbing protective oncophagy while triggering the oncophagy that is lethal to tumor cells. In this review, we focus on the trends in current therapeutics as well as various challenges in clinical trials to address the oncophagic dilemma and evaluate the potential of these developing therapies. A detailed analysis of the clinical and pre-clinical scenario of the anticancer medicines highlights the various inducers and inhibitors of autophagy. The ways in which tumor stage, the microenvironment and combination drug treatment continue to play an important tactical role are discussed. Moreover, autophagy targets also play a crucial role in developing the best possible solution to this oncophagy paradox. In this review, we provide a comprehensive update on the current clinical impact of autophagy-based cancer therapeutic drugs and try to lessen the gap between translational medicine and clinical science.

Gemcitabine and mitomycin induced autophagy regulates cancer stem cell pool in urothelial carcinoma cells

Urothelial carcinoma (UC) is characterized by therapeutic resistance and frequent tumor relapse. It has been suggested that UC are driven by a rare subset of cancer stem cells (CSCs). In order to understand UC recurrence post therapy, we investigated the behavior of urothelial CSCs after exposure to commonly used chemotherapeutic agents, gemcitabine (GC) and mitomycin (MM). Although, the role of autophagy in CSC maintenance is well documented, the relationship of autophagy and CSCs with respect to drug resistance remains elusive. In the present study, we found that both GC and MM increased the percentage of CSCs in primary cultured urothelial carcinoma cells (UCC). These CSCs exhibited higher autophagy flux and higher expression of glycolytic genes. Inhibition of autophagy led to decrease in the expression of glycolysis genes. Inhibition of autophagy and glycolysis caused decrease in expression of stemness genes (Oct-4, Nanog), drug resistance genes (ABCG2, MDR1) and sensitized CSCs to GC and MM induced apoptosis. This finding suggests that autophagy and glycolysis may play a central role in drug resistance. Altogether, we conclude that autophagy may support cell survival by buffering bioenergetic demands for maintenance of high glycolytic flux in CSCs. Therefore, autophagy-based, "customized" combinatorial approaches may provide a new method to counter CSC-driven resistance and may prevent relapse in UC. The synergistic cytotoxic effect of GC/ MM with autophagy inhibitor (chloroquine) or with glycolytic inhibitor (2-deoxyglucose) may be of help in improving the outcome in patients with urothelial carcinoma of urinary bladder.

Inhibition of High Basal Level of Autophagy Induces Apoptosis in Human Bladder Cancer Cells

PURPOSE

Cancer cells adapt to stress by activation of the autophagy pathway primed for survival. A high basal level of autophagic activity was found in human bladder cancer cell lines. We studied the significance of the phenomenon on cancer cell survival.

MATERIALS AND METHODS

The immortalized human bladder epithelial cell line SV-HUC-1 and the human bladder cancer cell lines RT-4 and 5637 together with human bladder cancer specimens collected from patients were used. A commercially available bladder cancer microarray was applied to confirm the findings. LC3 (light chain-3) II protein detection was done to determine the presence of autophagy. Caspase 3 and DNA fragmentation was performed to detect apoptosis.

RESULTS

Bladder cancer cell lines showed activated autophagic flux compared to SV-HUC-1 cells, prostate cancer cells and breast cancer cells. Results were confirmed in human bladder cancer specimens. Autophagy inhibition by Baf (bafilomycin) A1, or by knockdown of ATG (autophagy related protein) 7 or 12 induced cytotoxicity in multiple human bladder cell lines. Induction of apoptosis was found in cells with autophagy inhibition. Although the disruption of mitochondria membrane potential or the generation of reactive oxygen species was detected in Baf A1 treated cells, intensity was mild and not thought to be related to apoptosis of bladder cancer cells.

CONCLUSIONS

Our results indicate that autophagy is required for the growth and survival of human bladder cancer cells.

Induction of cytosine arabinoside-resistant human myeloid leukemia cell death through autophagy regulation by hydroxychloroquine

We investigated the effects of the autophagy inhibitor hydroxychloroquine (HCQ) on cell death of cytosine arabinoside (Ara-C)-resistant human acute myeloid leukemia (AML) cells. Ara-C-sensitive (U937, AML-2) and Ara-C-resistant (U937/AR, AML-2/AR) human AML cell lines were used to evaluate HCQ-regulated cytotoxicity, autophagy, and apoptosis as well as effects on cell death-related signaling pathways. We found that HCQ-induced dose- and time-dependent cell death in Ara-C-resistant cells compared to Ara-C-sensitive cell lines. The extent of cell death and features of HCQ-induced autophagic markers including increase in microtubule-associated protein light chain 3 (LC3) I conversion to LC3-II, beclin-1, ATG5, as well as green fluorescent protein-LC3 positive puncta and autophagosome were remarkably greater in U937/AR cells. Also, p62/SQSTM1 was increased in response to HCQ. p62/SQSTM1 protein interacts with both LC3-II and ubiquitin protein and is degraded in autophagosomes. Therefore, a reduction of p62/SQSTM1 indicates increased autophagic degradation, whereas an increase of p62/SQSTM1 by HCQ indicates inhibited autophagic degradation. Knock down of p62/SQSTM1 using siRNA were prevented the HCQ-induced LC3-II protein level as well as significantly reduced the HCQ-induced cell death in U937/AR cells. Also, apoptotic cell death and caspase activation in U937/AR cells were increased by HCQ, provided evidence that HCQ-induced autophagy blockade. Taken together, our data show that HCQ-induced apoptotic cell death in Ara-C-resistant AML cells through autophagy regulation.

Autophagy in Cancer Stem Cells: A Potential Link Between Chemoresistance, Recurrence, and Metastasis

Cancer cells require an uninterrupted nutritional supply for maintaining their proliferative needs and this high demand in concurrence with inadequate supply of blood and nutrition induces stress in these cells. These cells utilize various strategies like high glycolytic flux, redox signaling, and modulation of autophagy to avoid cell death and overcome nutritional deficiency. Autophagy allows the cell to generate ATP and other essential biochemical building blocks necessary under such adverse conditions. It is emerging as a decisive process in the development and progression of pathophysiological conditions that are associated with increased cancer risk. However, the precise role of autophagy in tumorigenesis is still debatable. Autophagy is a novel cytoprotective process to augment tumor cell survival under nutrient or growth factor starvation, metabolic stress, and hypoxia. The tumor hypoxic environment may provide site for the enrichment/expansion of the cancer stem cells (CSCs) and successive rapid tumor progression. CSCs are characteristically resistant to conventional anticancer therapy, which may contribute to treatment failure and tumor relapse. CSCs have the potential to regenerate for an indefinite period, which can impel tumor metastatic invasion. From last decade, preclinical research has focused on the diversity in CSC content within tumors that could affect their chemo- or radio-sensitivity by impeding with mechanisms of DNA repair and cell cycle progression. The aim of this review is predominantly directed on the recent developments in the CSCs during cancer treatment, role of autophagy in maintenance of CSC populations and their implications in the development of promising new cancer treatment options in future.