Chemoresistance is associated with Beclin-1 and PTEN expression in epithelial ovarian cancers

Role of circRNAs in regulating cell death in cancer: a comprehensive review

Despite multiple diagnostic and therapeutic advances, including surgery, radiation therapy, and chemotherapy, cancer preserved its spot as a global health concern. Prompt cancer diagnosis, treatment, and prognosis depend on the discovery of new biomarkers and therapeutic strategies. Circular RNAs (circRNAs) are considered as a stable, conserved, abundant, and varied group of RNA molecules that perform multiple roles such as gene regulation. There is evidence that circRNAs interact with RNA-binding proteins, especially capturing miRNAs. An extensive amount of research has presented the substantial contribution of circRNAs in various types of cancer. To fully understand the linkage between circRNAs and cancer growth as a consequence of various cell death processes, including autophagy, ferroptosis, and apoptosis, more research is necessary. The expression of circRNAs could be controlled to limit the occurrence and growth of cancer, providing a more encouraging method of cancer treatment. Consequently, it is critical to understand how circRNAs affect various forms of cancer cell death and evaluate whether circRNAs could be used as targets to induce tumor death and increase the efficacy of chemotherapy. The current study aims to review and comprehend the effects that circular RNAs exert on cell apoptosis, autophagy, and ferroptosis in cancer to investigate potential cancer treatment targets.

The Interplay between Autophagy and Mitochondria in Cancer

Besides producing cellular energy, mitochondria are crucial in controlling oxidative stress and modulating cellular metabolism, particularly under stressful conditions. A key aspect of this regulatory role involves the recycling process of autophagy, which helps to sustain energy homeostasis. Autophagy, a lysosome-dependent degradation pathway, plays a fundamental role in maintaining cellular homeostasis by degrading damaged organelles and misfolded proteins. In the context of tumor formation, autophagy significantly influences cancer metabolism and chemotherapy resistance, contributing to both tumor suppression and surveillance. This review focuses on the relationship between mitochondria and autophagy, specifically in the context of cancer progression. Investigating the interaction between autophagy and mitochondria reveals new possibilities for cancer treatments and may result in the development of more effective therapies targeting mitochondria, which could have significant implications for cancer treatment. Additionally, this review highlights the increasing understanding of autophagy's role in tumor development, with a focus on modulating mitochondrial function and autophagy in both pre-clinical and clinical cancer research. It also explores the potential for developing more-targeted and personalized therapies by investigating autophagy-related biomarkers.

Targeting autophagy and beyond: Deconvoluting the complexity of Beclin-1 from biological function to cancer therapy

Beclin-1 is the firstly-identified mammalian protein of the autophagy machinery, which functions as a molecular scaffold for the assembly of PI3KC3 (class III phosphatidylinositol 3 kinase) complex, thus controlling autophagy induction and other cellular trafficking events. Notably, there is mounting evidence establishing the implications of Beclin-1 in diverse tumorigenesis processes, including tumor suppression and progression as well as resistance to cancer therapeutics and CSC (cancer stem-like cell) maintenance. More importantly, Beclin-1 has been confirmed as a potential target for the treatment of multiple cancers. In this review, we provide a comprehensive survey of the structure, functions, and regulations of Beclin-1, and we discuss recent advances in understanding the controversial roles of Beclin-1 in oncology. Moreover, we focus on summarizing the targeted Beclin-1-regulating strategies in cancer therapy, providing novel insights into a promising strategy for regulating Beclin-1 to improve cancer therapeutics in the future.

The multifaced role and therapeutic regulation of autophagy in ovarian cancer

Ovarian cancer (OC) is one of the tumors that occurs most frequently in women. Autophagy is involved in cell homeostasis, biomolecule recycling, and survival, making it a potential target for anti-tumor drugs. It is worth noting that growing evidence reveals a close link between autophagy and OC. In the context of OC, autophagy demonstrates activity as both a tumor suppressor and a tumor promoter, depending on the context. Autophagy's exact function in OC is greatly reliant on the tumor microenvironment (TME) and other conditions, such as hypoxia, nutritional deficiency, chemotherapy, and so on. However, what can be concluded from different studies is that autophagy-related signaling pathways, especially PI3K/AKT/mTOR axis, increase in advanced stages and malignant phenotype of the disease reduces autophagy and ultimately leads to tumor progression. This study sought to present a thorough understanding of the role of autophagy-related signaling pathways in OC and existing therapies targeting these signaling pathways.

Role and mechanism of autophagy-regulating factors in tumorigenesis and drug resistance

A hallmark feature of tumorigenesis is uncontrolled cell division. Autophagy is regulated by more than 30 genes and it is one of several mechanisms by which cells maintain homeostasis. Autophagy promotes cancer progression and drug resistance. Several genes play important roles in autophagy-induced tumorigenesis and drug resistance including Beclin-1, MIF, HMGB1, p53, PTEN, p62, RAC3, SRC3, NF-2, MEG3, LAPTM4B, mTOR, BRAF and c-MYC. These genes alter cell growth, cellular microenvironment and cell division. Mechanisms involved in tumorigenesis and drug resistance include microdeletions, genetic mutations, loss of heterozygosity, hypermethylation, microsatellite instability and translational modifications at a molecular level. Disrupted or altered autophagy has been reported in hematological malignancies like lymphoma, leukemia and myeloma as well as multiple solid organ tumors like colorectal, hepatocellular, gall bladder, pancreatic, gastric and cholangiocarcinoma among many other malignancies. In addition, defects in autophagy also play a role in drug resistance in cancers like osteosarcoma, ovarian and lung carcinomas following treatment with drugs such as doxorubicin, paclitaxel, cisplatin, gemcitabine and etoposide. Therapeutic approaches that modulate autophagy are a novel future direction for cancer drug development that may help to prevent issues with disease progression and overcome drug resistance.

Autophagy signals orchestrate chemoresistance of gynecological cancers

Gynecological cancers are characterized by a high mortality rate when chemoresistance develops. Autophagy collaborates with apoptosis and participates in homeostasis of chemoresistance. Recent findings supported that crosstalk of necrotic, apoptotic and autophagic factors, and chemotherapy-driven hypoxia, oxidative stress and ER stress play critical roles in chemoresistance in gynecological cancers. Meanwhile, current studies have shown that autophagy could be regulated by and cooperate with metabolic regulator, survival factors, stemness factors and specific post-translation modification in chemoresistant tumor cells. Meanwhile, non-coding RNA and autophagy crosstalk also contribute to the chemoresistance. Until now, analysis of individual autophagy factors towards the clinical significance and chemoresistance in gynecological cancer is still lacking. We suggest comprehensive integrated analysis of cellular homeostasis and tumor microenvironment to clarify the role of autophagy and the associated factors in cancer progression and chemoresistance. Panel screening of pan-autophagic factors will pioneer the development of risk models for predicting efficacy of chemotherapy and guidelines for systematic treatment and precision medicine.

The Tumor Suppressor PTEN as Molecular Switch Node Regulating Cell Metabolism and Autophagy: Implications in Immune System and Tumor Microenvironment

Recent studies conducted over the past 10 years evidence the intriguing role of the tumor suppressor gene Phosphatase and Tensin Homolog deleted on Chromosome 10 PTEN in the regulation of cellular energy expenditure, together with its capability to modulate proliferation and survival, thus expanding our knowledge of its physiological functions. Transgenic PTEN mice models are resistant to oncogenic transformation, present decreased adiposity and reduced cellular glucose and glutamine uptake, together with increased mitochondrial oxidative phosphorylation. These acquisitions led to a novel understanding regarding the role of PTEN to counteract cancer cell metabolic reprogramming. Particularly, PTEN drives an “anti-Warburg state” in which less glucose is taken up, but it is more efficiently directed to the mitochondrial Krebs cycle. The maintenance of cellular homeostasis together with reduction of metabolic stress are controlled by specific pathways among which autophagy, a catabolic process strictly governed by mTOR and PTEN. Besides, a role of PTEN in metabolic reprogramming and tumor/stroma interactions in cancer models, has recently been established. The genetic inactivation of PTEN in stromal fibroblasts of mouse mammary glands, accelerates breast cancer initiation and progression. This review will discuss our novel understanding in the molecular connection between cell metabolism and autophagy by PTEN, highlighting novel implications regarding tumor/stroma/immune system interplay. The newly discovered action of PTEN opens innovative avenues for investigations relevant to counteract cancer development and progression.

Overcoming cisplatin resistance by targeting the MTDH-PTEN interaction in ovarian cancer with sera derived from rats exposed to Guizhi Fuling wan extract

Background

The well-known traditional Chinese herbal formula Guizhi Fuling Wan (GFW) was recently reported to improve the curative effects of chemotherapy for ovarian cancer with few clinical side effects. The present study aimed to investigate the reversal mechanism of sera derived from rats exposed to Guizhi Fuling Wan extract (GFWE) in cisplatin-resistant human ovarian cancer SKOV3/DDP cells; the proteins examined included phosphatase and tensin homolog (PTEN) and metadherin (MTDH), and the possible protein interaction between PTEN and MTDH was explored.

Methods

GFWE was administered to healthy Wistar rats, and the sera were collected after five days. The PubMed and CNKI databases were searched for literature on the bioactive blood components in the sera. The systemsDock website was used to predict potential PTEN/MTDH interactions with the compounds. RT-qPCR, western blotting, and immunofluorescence analyses were used to analyze the mRNA and protein levels of MTDH and PTEN. Laser confocal microscopy and coimmunoprecipitation (co-IP) were used to analyze the colocalization and interaction between MTDH and PTEN.

Results

Sixteen bioactive compounds were identified in GFWE sera after searching the PubMed and CNKI databases. The systemsDock website predicted the potential PTEN/MTDH interactions with the compounds. RT-qPCR, western blotting, and immunofluorescence analyses showed decreased MTDH expression and increased PTEN expression in the sera. Laser confocal microscopy images and coimmunoprecipitation (co-IP) analyses demonstrated that a colocalization and interaction occurred between MTDH and PTEN, and the addition of the sera changed the interaction status.

Conclusions

GFWE restored sensitivity to cisplatin by inhibiting MTDH expression, inducing PTEN expression, and improving the interaction between MTDH and PTEN in SKOV3/DDP cells, and these proteins and their interaction may serve as potential targets for cancer treatment. The sera may represent a new source of anticancer compounds that could help to manage chemoresistance more efficiently and safely.

Ovarian Tumor Cell Expression of Claudin-4 Reduces Apoptotic Response to Paclitaxel

A significant factor contributing to poor survival rates for patients with ovarian cancer is the insensitivity of tumors to standard-of-care chemotherapy. In this study, we investigated the effect of claudin-4 expression on ovarian tumor cell apoptotic response to cisplatin and paclitaxel. We manipulated claudin-4 gene expression by silencing expression [short hairpin RNA (shRNA)] in cells with endogenously expressed claudin-4 or overexpressing claudin-4 in cells that natively do not express claudin-4. In addition, we inhibited claudin-4 activity with a claudin mimic peptide (CMP). We monitored apoptotic response by caspase-3 and Annexin V binding. We examined proliferation rate by counting the cell number over time as well as measuring the number of mitotic cells. Proximity ligation assays, immunoprecipitation (IP), and immunofluorescence were performed to examine interactions of claudin-4. Western blot analysis of tubulin in cell fractions was used to determine the changes in tubulin polymerization with changes in claudin-4 expression. Results show that claudin-4 expression reduced epithelial ovarian cancer (EOC) cell apoptotic response to paclitaxel. EOCs without claudin-4 proliferated more slowly with enhanced mitotic arrest compared with the cells expressing claudin-4. Furthermore, our results indicate that claudin-4 interacts with tubulin, having a profound effect on the structure and polymerization of the microtubule network. In conclusion, we demonstrate that claudin-4 reduces the ovarian tumor cell response to microtubule-targeting paclitaxel and disrupting claudin-4 with CMP can restore apoptotic response. IMPLICATIONS: These results suggest that claudin-4 expression may provide a biomarker for paclitaxel response and can be a target for new therapeutic strategies to improve response.

Contribution of FPR and TLR9 to hypoxia-induced chemoresistance of ovarian cancer cells

Background/purpose

The aim of this study was to investigate the role and mechanisms of the formyl peptide receptor (FPR) and the toll-like receptor 9 (TLR9) in hypoxia-induced chemoresistance of human ovarian cancer cells.

Materials and methods

SKOV3 cells were exposed to hypoxia for 24 hours, the supernatant was collected to stimulate normoxia-cultured SKOV3, and the inhibition rate of cell growth was detected with CCK8 test. The agonist of TLR9 CpG ODN and the agonist of FPR fMLF were applied to investigate the chemosensitivity of SKOV3 cells to cisplatin. The cells were also treated with FPR antagonist t-Boc or TLR9 antagonist CQ. Western blot was applied to detect protein levels of FPR, TLR9, MRP, P-gp, p53 and Beclin-1. Immunofluorescence staining was applied to observe the distribution of TLR9 in SKOV3 cells.

Results

Hypoxia exposure reduced the inhibition rate of cisplatin on SKOV3 cells. WB showed that FPR and TLR9 were expressed in human ovarian cancer tissues and SKOV3 cells, and the levels were increased with longer hypoxia time. After SKOV3 was stimulated with fMLF or ODN2006, cisplatin-induced inhibition rate was significantly decreased. tBoc and CQ significantly attenuated hypoxia supernatant-induced chemoresistance of SKOV3 cells. Hypoxia supernatants significantly increased MRP, P-gp, p53 and Beclin-1 proteins in SKOV3 cells, which were significantly reduced by tBoc.

Conclusion

Hypoxia upregulates the expression of FPR and TLR9, and promotes the release of ligands for both receptors in human ovarian cancer cell line. FPR and TLR9 may be noval targets for chemosensitizing to ovarian cancer cells.

Genes involved in the regulation of different types of autophagy and their participation in cancer pathogenesis

Autophagy is a highly conserved mechanism of self-digestion that removes damaged organelles and proteins from cells. Depending on the way the protein is delivered to the lysosome, four basic types of autophagy can be distinguished: macroautophagy, selective autophagy, chaperone-mediated autophagy and microautophagy. Macroautophagy involves formation of autophagosomes and is controlled by specific autophagy-related genes. The steps in macroautophagy are initiation, phagophore elongation, autophagosome maturation, autophagosome fusion with the lysosome, and proteolytic degradation of the contents. Selective autophagy is macroautophagy of a specific cellular component. This work focuses on mitophagy (selective autophagy of abnormal and damaged mitochondria), in which the main participating protein is PINK1 (phosphatase and tensin homolog-induced putative kinase 1). In chaperone-mediated autophagy, the substrate is bound to a heat shock protein 70 chaperone before it is delivered to the lysosome. The least characterized type of autophagy is microautophagy, which is the degradation of very small molecules without participation of an autophagosome. Autophagy can promote or inhibit tumor development, depending on the severity of the disease, the type of cancer, and the age of the patient. This paper describes the molecular basis of the different types of autophagy and their importance in cancer pathogenesis.

Beclin1 overexpression suppresses tumor cell proliferation and survival via an autophagy‑dependent pathway in human synovial sarcoma cells

Beclin1 is an important autophagy‑related prot-ein, which is involved in both autophagy and apoptosis. In recent years, the antitumor effect of Beclin1 has received increased attention. In the present study, we established a stable Beclin1‑overexpressing cell line with SW982 human synovial sarcoma cells. We found that Beclin1 overexpression decreased the cell viability, inhibited proliferation and induced apoptosis in SW982 cells. The expression levels of Bcl‑2 and PCNA were decreased, while the levels of cleaved‑caspase‑3 and cleaved‑PARP were increased. Beclin1 is closely related with autophagy, thus the autophagy‑related markers LC3 and p62 were detected by western blot analysis, and transmission electron microscopy was used to observe autophagosomes. The results showed that the expression level of LC3II was increased and that of p62 was decreased. Moreover, many double membrane‑enclosed autophagosomes were found in cells with Beclin1 overexpression, which indicated that the autophagic activity was enhanced. To explore the effect of autophagy on the viability of SW982 cells, Atg5 was knocked down using siRNA to inhibit the autophagic activity. We found that autophagy contributed to the decrease in cell viability. Knockdown of Atg5 increased the viability and decreased the apoptotic rate of SW982 cells with Beclin1 overexpression. The expression level of Bcl‑2 was increased, while the expression levels of cleaved‑caspase‑3 and cleaved‑PARP were decreased. We also found that the Akt/Bcl‑2/caspase‑9 pathway was involved. The phosphorylation of AKT was positively correlated with cell viability. The cleavage of caspase‑9 was increased by Beclin1 overexpression and decreased by inhibition of autophagy. Altogether, our results suggested that both autophagy and apoptosis contributed to the antitumor effect of Beclin1 in SW982 cells.

Autophagy as an emerging therapy target for ovarian carcinoma

Autophagy is a conserved cellular self-digestion pathway for maintenance of homeostasis under basal and stressed conditions. Autophagy plays pivotal roles in the pathogenesis of many diseases, such as aging-related diseases, autoimmune diseases, cardiovascular diseases, and cancers. Of special note is that accumulating data suggest an intimate relationship between autophagy and ovarian carcinoma. Autophagy is well identified to act as either as a tumor-suppressor or as a tumor-promoter in ovarian carcinoma. The exact function of autophagy in ovarian carcinoma is highly dependent on the circumstances of cancer including hypoxic, nutrient-deficient, chemotherapy and so on. However, the mechanism underlying autophagy associated with ovarian carcinoma remains elusive, the precise role of autophagy in ovarian carcinoma also remains undetermined. In this review, we tried to sum up and discuss recent research achievements of autophagy in ovarian cancer. Moreover, waves of novel therapies ways for ovarian carcinoma based on the functions of autophagy were collected.

New Insights Into Beclin-1: Evolution and Pan-Malignancy Inhibitor Activity

Autophagy is a functionally conserved self-degradation process that facilitates the survival of eukaryotic life via the management of cellular bioenergetics and maintenance of the fidelity of genomic DNA. The first known autophagy inducer was Beclin-1. Beclin-1 is expressed in multicellular eukaryotes ranging throughout plants to animals, comprising a nonmonophyllic group, as shown in this report via aggressive BLAST searches. In humans, Beclin-1 is a haploinsuffient tumor suppressor as biallelic deletions have not been observed in patient tumors clinically. Therefore, Beclin-1 fails the Knudson hypothesis, implicating expression of at least one Beclin-1 allele is essential for cancer cell survival. However, Beclin-1 is frequently monoallelically deleted in advanced human cancers and the expression of two Beclin-1 allelles is associated with greater anticancer effects. Overall, experimental evidence suggests that Beclin-1 inhibits tumor formation, angiogenesis, and metastasis alone and in cooperation with the tumor suppressive molecules UVRAG, Bif-1, Ambra1, and MDA-7/IL-24 via diverse mechanisms of action. Conversely, Beclin-1 is upregulated in cancer stem cells (CSCs), portending a role in cancer recurrence, and highlighting this molecule as an intriguing molecular target for the treatment of CSCs. Many aspects of Beclin-1's biological effects remain to be studied. The consequences of these BLAST searches on the molecular evolution of Beclin-1, and the eukaryotic branches of the tree of life, are discussed here in greater detail with future inquiry focused upon protist taxa. Also in this review, the effects of Beclin-1 on tumor suppression and cancer malignancy are discussed. Beclin-1 holds significant promise for the development of novel targeted cancer therapeutics and is anticipated to lead to a many advances in our understanding of eukaryotic evolution, multicellularity, and even the treatment of CSCs in the coming decades.

Hydrogel Environment Supports Cell Culture Expansion of a Grade IV Astrocytoma

Malignant astrocytomas are aggressive cancers of glial origin that can develop into invasive brain tumors. The disease has poor prognosis and high recurrence rate. Astrocytoma cell lines of human origin are an important tool in the experimental pathway from bench to bedside because they afford a convenient intermediate system for in vitro analysis of brain cancer pathogenesis and treatment options. We undertook the current study to determine whether hydrogel culture methods could be adapted to support the growth of astrocytoma cell lines, thereby facilitating a system that may be biologically more similar to in vivo tumor tissue. Our experimental protocols enabled maintenance of Grade IV astrocytoma cell lines in conventional monolayer culture and in the extracellular matrix hydrogel, Geltrex™. Light and fluorescence microscopy showed that hydrogel environments promoted cellular reorganization from dispersed cells into multilayered aggregates. Transmission electron microscopy revealed the prevalence of autophagy and nuclear membrane distortions in both culture systems. Analysis of microarray Gene Expression Omnibus (GEO) DataSets highlighted expression of genes implicated in pathways for cancer progression and autophagy. A pilot quantitative polymerase chain reaction (qPCR) analysis of the autophagic biomarkers, Beclin 1 (BECN1) and microtubule-associated proteins 1A/1B light chain 3B (MAP1LC3B), with two reference genes (beta actin, ACTB; glyceraldehyde 3-phosphate dehydrogenase, GAPDH), uncovered a relative increase of BECN1 and LC3B in hydrogel cultures of astrocytoma as compared to the monolayer. Taken together, results establish that ultrastructural and molecular characteristics of autophagy are features of this astrocytoma cell line, and that hydrogel culture systems can afford novel opportunities for in vitro studies of glioma.

Upregulation of microRNA-18b induces phosphatase and tensin homolog to accelerate the migration and invasion abilities of ovarian cancer

Ovarian cancer (OC) is the most common cause of mortality from malignant gynecological cancers. Its lethality is mainly a result of tumors that are difficult to detect at the early stage and a lack of effective systemic therapy for advanced status cancer. MicroRNAs (miRNAs/miRs) are a category of single-stranded non-coding small RNAs that bind to their target mRNAs, and aberrant expression levels of miRNAs may serve key roles in regulating cell migration and invasion of various types of human cancer. Previous studies have demonstrated that miR-18b may function as an oncogene in numerous types of tumors, but its role and molecular mechanism in OC remained unclear. The present study demonstrated for the first time that miR-18b expression was significantly upregulated in OC tissues and cells. An increased miR-18b expression level was positively associated with tumor grade and lymph node metastasis. An in vitro assay revealed that exogenous inhibition of miR-18b expression may markedly inhibit OC cell migratory and invasive activities, whereas overexpression of miR-18b enhanced cell migratory and invasive abilities. Of note, using in silico methodologies and luciferase reporter assays, it was demonstrated that phosphatase and tensin homolog (PTEN) was a direct target of miR-18b in OC cells. Furthermore, knockdown of miR-18b expression may significantly decrease mRNA and protein expression levels of endogenous PTEN. The results of the present study highlighted that upregulation of miR-18b was involved in OC cell metastasis by directly targeting PTEN. Inhibition of miR-18b may be a novel effective diagnostic and therapeutic measure for OC.

Effect of inhibiting Beclin-1 expression on autophagy, proliferation and apoptosis in colorectal cancer

The present study aimed to investigate the molecular mechanisms and effect of Beclin-1 on autophagy, proliferation and apoptosis in the colorectal cancer (CRC) HCT116 and SW620 cells. Beclin-1 was silenced by RNA interference (RNAi) in HTC116 and SW620 cells. Reverse transcription-polymerase chain reaction and western blot were used to measure the expression of Beclin-1. The percentage of apoptotic cells was analyzed by cell counting kit-8 (CCK-8) and flow cytometry (FCM). Cell cycle and cell proliferation were analyzed by FCM and the MTT assay. The present study created 3 groups in the two cell lines, consisting of the targeting siRNA (TS) group, in which Beclin-1 was partially silenced, non-specific siRNA (NS) group and control group (CG; without transfection). By siRNA transfection, the mRNA and protein level of Beclin-1 in the TS group were significantly inhibited compared with the NS group and CG (P<0.05). After 0, 24, 48 and 72 h, the survival rate of the cells in the TS group was significantly decreased compared with the survival rate of the cells in the NS group and CG, as detected by CCK-8 methods (P<0.05). FCM and MTT results showed the apoptotic rate of the cells in the TS group was significantly decreased compared with the rate in the NS group and CG (P<0.05), and the proliferation of the cells in the NS group was evidently increased compared with the CG. In conclusion, Beclin-1 played an important role in regulating autophagy, proliferation and apoptosis in HCT116 and SW620 cells. The inhibition of Beclin-1 by RNAi suppressed the autophagic activity and proliferation, but promoted apoptosis in CRC cells. Beclin-1 was the new target of gene therapy for CRC.

Lysosomal acid phosphatase 2 is an unfavorable prognostic factor but is associated with better survival in stage II colorectal cancer patients receiving chemotherapy

Colorectal cancer (CRC) is one of the leading cancers worldwide. Surgery is the main therapeutic modality for stage II CRC. However, the implementation of adjuvant chemotherapy remains controversial and is not universally applied so far. In this study, we found that the protein expression of lysosomal acid phosphatase 2 (ACP2) was increased in CRC and that stage II CRC patients with high ACP2 expression showed a poorer outcome than those with low ACP2 expression (p = 0.004). To investigate this discrepancy, we analyzed the relation between ACP2 expression and several clinical cofactors.

Among patients who received chemotherapy, those with an high expression of ACP2 showed better survival in both stage II and III CRC than those with low ACP2 expression. In stage II CRC patients, univariate analysis showed ACP2 expression and T stage to be cofactors significantly associated with overall survival (ACP2: p = 0.006; T stage: p = 0.034). Multivariate Cox proportion hazard model analysis also revealed ACP2 to be an independent prognostic factor for overall survival (ACP2: p = 0.006; T stage: p = 0.041). Furthermore, ACP2-knockdown CRC cells showed an increase in chemoresistance to 5-FU treatment and increased proliferation marker in the ACP2 knockdown clone.

Taken together, our results suggested that ACP2 is an unfavorable prognostic factor for stage II CRC and may serve as a potential chemotherapy-sensitive marker to help identify a subset of stage II and III CRC patients for whom chemotherapy would improve survival.

Chemoresistance and targeted therapies in ovarian and endometrial cancers

Gynecological cancers are known for being very aggressive at their advanced stages. Indeed, the survival rate of both ovarian and endometrial cancers is very low when diagnosed lately and the success rate of current chemotherapy regimens is not very efficient. One of the main reasons for this low success rate is the acquired chemoresistance of these cancers during their progression. The mechanisms responsible for this acquired chemoresistance are numerous, including efflux pumps, repair mechanisms, survival pathways (PI3K/AKT, MAPK, EGFR, mTOR, estrogen signaling) and tumor suppressors (P53 and Par-4). To overcome these resistances, a new type of therapy has emerged named targeted therapy. The principle of targeted therapy is simple, taking advantage of changes acquired in malignant cancer cells (receptors, proteins, mechanisms) by using compounds specifically targeting these, thus limiting their action on healthy cells. Targeted therapies are emerging and many clinical trials targeting these pathways, frequently involved in chemoresistance, have been tested on gynecological cancers. Despite some targets being less efficient than expected as mono-therapies, the combination of compounds seems to be the promising avenue. For instance, we demonstrate using ChIP-seq analysis that estrogen downregulate tumor suppressor Par-4 in hormone-dependent cells by directly binding to its DNA regulatory elements and inhibiting estrogen signaling could reinstate Par-4 apoptosis-inducing abilities. This review will focus on the chemoresistance mechanisms and the clinical trials of targeted therapies associated with these, specifically for endometrial and ovarian cancers.

Regulation of multidrug resistance by microRNAs in anti-cancer therapy

Multidrug resistance (MDR) remains a major clinical obstacle to successful cancer treatment. Although diverse mechanisms of MDR have been well elucidated, such as dysregulation of drugs transporters, defects of apoptosis and autophagy machinery, alterations of drug metabolism and drug targets, disrupti on of redox homeostasis, the exact mechanisms of MDR in a specific cancer patient and the cross-talk among these different mechanisms and how they are regulated are poorly understood. MicroRNAs (miRNAs) are a new class of small noncoding RNAs that could control the global activity of the cell by post-transcriptionally regulating a large variety of target genes and proteins expression. Accumulating evidence shows that miRNAs play a key regulatory role in MDR through modulating various drug resistant mechanisms mentioned above, thereby holding much promise for developing novel and more effective individualized therapies for cancer treatment. This review summarizes the various MDR mechanisms and mainly focuses on the role of miRNAs in regulating MDR in cancer treatment.

Novel mechanisms and approaches to overcome multidrug resistance in the treatment of ovarian cancer

Ovarian cancer remains the leading cause of gynecological cancer-related mortality despite the advances in surgical techniques and chemotherapy drugs over the past three decades. Multidrug resistance (MDR) to chemotherapy is the major cause of treatment failure. Previous research has focused mainly on strategies to reverse MDR by targeting the MDR1 gene encoded P-glycoprotein (Pgp) with small molecular compound inhibitors. However, prior Pgp inhibitors have shown very limited clinical success because these agents have relatively low potency and high toxicity. Therefore, identification of more specific and potent new inhibitors would be useful. In addition, emerging evidence suggests that cancer stem cells (CSCs), deregulated non-coding RNA (ncRNA), autophagy, and tumor heterogeneity also contribute significantly to drug sensitivity/resistance in ovarian cancer. This review summarizes these novel mechanisms of MDR and evaluates several new concepts to overcome MDR in the treatment of ovarian cancer. These new strategies include overcoming MDR with more potent and specific Pgp inhibitors, targeting CSCs and ncRNA, modulating autophagy signaling pathway, and targeting tumor heterogeneity.

HCV core protein represses the apoptosis and improves the autophagy of human hepatocytes

OBJECTIVES

This study aims to investigate the influence on human hepatocytes apoptosis and autophagy by the hepatitis C virus (HCV) core protein.

METHODS

QSG-7701, a human-derived non-neoplastic liver cell line, was transfected with PIRES-core vector that was a eukaryotic vector to express HCV core protein. Fluorescence microscope was used to observe the changes of nuclei in apoptosis cells by Annex in V-FITC/PI double staining. Flow cytometry was applied to detect the rate of cell apoptosis. Western blotting was used to detect the expression of HCV core protein, transcription factor nuclear factor-kappa B (NF-κB), autophagic biomarker microtubule associated protein 1 light chain 3 (LC3), and Beclin-1.

RESULTS

The apoptosis rate was significantly lower (P < 0.05) in QSG7701/core group (transfected with PIRES-core vector, (1.34±0.07)%) than in QSG7701 group (no transfection, (2.35±0.11)%) and in QSG7701 QSG7701/pcDNA3.1 group (transfected with pcDNA3.1 vector, (2.58±0.1)%). NF-κB expression was up-expressed in QSG7701/core group than in QSG7701/pcDNA3.1 group and QSG7701 group (P < 0.05). LC3-II expression and Beclin-1 expression was significant higher in QSG7701/core group than in the QSG7701/pcDNA3.1 group and QSG7701 group (P < 0.05).

CONCLUSION

HCV core protein can repress the apoptosis and improve the autophagy of QSG7701 through up-regulating NF-κB and Beclin-1 expression.

Expression of NF-κB and PTEN in primary epithelial ovarian carcinoma and the correlation with chemoresistance

The present study aims to investigate the relationship of NF-κB p65 and PTEN protein with chemotherapy resistance in ovarian cancer by measuring their expression in primary epithelial ovarian cancer, and to explore the correlation of the expression of these two proteins with ovarian carcinoma and their clinical significance. Ovarian cancer patients (n = 161) were divided into two groups: sensitive group (n = 82) and resistant group (n = 79). Expression of NF-κB p65 and PTEN protein in the ovarian cancer tissues was determined using immunohistochemistry to assess the relationship and correlation between the expression levels of these two proteins and chemotherapy resistance of ovarian carcinoma. The Cox model was used to analyze the independent risk factors associated with ovarian cancer prognosis. The expression of NF-κB p65 in the sensitive group (68.29%) was lower than that of the resistant group (94.94%). In contrast, the expression of PTEN protein in the sensitive group (50.00%) was higher than that of the resistant group (17.72%). Expression of NF-κB p65 was negatively correlated with that of PTEN protein in ovarian cancer tissue (rs = -0.246, P = 0.002). Expression of NF-κB p65 or PTEN protein and surgical stage of ovarian cancer were independent risk factors associated with chemoresistance (all P < 0.05). Low expression of PTEN and high expression of NF-κB are significant risk factors for chemotherapy resistance of ovarian cancer patients.