Current Opinions on Chemoresistance: An Overview

Deciphering cellular and molecular mechanism of MUC13 mucin involved in cancer cell plasticity and drug resistance

There has been a surge of interest in recent years in understanding the intricate mechanisms underlying cancer progression and treatment resistance. One molecule that has recently emerged in these mechanisms is MUC13 mucin, a transmembrane glycoprotein. Researchers have begun to unravel the molecular complexity of MUC13 and its impact on cancer biology. Studies have shown that MUC13 overexpression can disrupt normal cellular polarity, leading to the acquisition of malignant traits. Furthermore, MUC13 has been associated with increased cancer plasticity, allowing cells to undergo epithelial-mesenchymal transition (EMT) and metastasize. Notably, MUC13 has also been implicated in the development of chemoresistance, rendering cancer cells less responsive to traditional treatment options. Understanding the precise role of MUC13 in cellular plasticity, and chemoresistance could pave the way for the development of targeted therapies to combat cancer progression and enhance treatment efficacy.

Role of exosomes in the communication and treatment between OSCC and normal cells

Oral squamous cell carcinoma (OSCC) is a prevalent cancer that needs new therapeutic targets due to the poor postoperative prognosis in patients. Exosomes are currently one of important research areas owing to their unique properties. Exosomes are capable of acting as drug transporters, as well as facilitating interactions between OSCC and normal cells. Exosomes can be detected in body fluids such as blood, urine, cerebrospinal fluid, and bile. When exosomes are released from donor cells, they can carry various bioactive molecules to recipient cells, where these molecules participate in biological processes. This review highlights the mechanisms of exosome transfer between normal and OSCC cells. Exosomes isolated from donor OSCC cells can carry circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs) and play a role in signaling processes in the recipient OSCC cells, human umbilical vein endothelial cells, and macrophages. Exosomes secreted by carcinoma-associated fibroblasts, macrophages, and stem cells can also enter the recipient OSCC cells and modulate signaling events in these cells. Exosomes isolated from OSCC plasma, serum, and saliva are also associated with OSCC prognosis. Furthermore, while exosomes were shown to be associated with chemotherapy resistance in OSCC, they can also be used for drug delivery during OSCC treatment. In this paper, we reviewed the molecular mechanisms and functions of exosomes from different cell sources in OSCC cells, providing a basis for diagnosis and prognosis prediction in OSCC patients, and offering guidance for the design of molecular targets carried by exosomes in OSCC.

A novel nomogram and risk stratification system predicting the cancer-specific survival of patients with gastric neuroendocrine carcinoma: a study based on SEER database and external validation

BACKGROUND

Gastric neuroendocrine carcinoma (GNEC) is a rare histology of gastric cancer. The retrospective study was designed to construct and validate a nomogram for predicting the cancer-specific survival (CSS) of postoperative GNEC patients.

METHODS

Data for 28 patients from the Hangzhou TCM Hospital were identified as the external validation cohort. A total of 1493 patients were included in the SEER database and randomly assigned to the training group (1045 patients) and internal validation group (448 patients). The nomogram was constructed using the findings of univariate and multivariate Cox regression studies. The model was evaluated by consistency index (C-index), calibration plots, and clinical net benefit. Finally, the effect between the nomogram and AJCC staging system was compared by net reclassification index (NRI) and integrated discrimination improvement (IDI).

RESULTS

Age, gender, grade, T stage, N stage, metastasis, primary site, tumor size, RNE, and chemotherapy were incorporated in the nomogram. The C-indexes were 0.792 and 0.782 in the training and internal verification sets. The 1-, 3-, and 5-year CSS predicted by the nomogram and actual measurements had good agreement in calibration plots. The 1-, 3-, and 5-year NRI were 0.21, 0.29, and 0.37, respectively. The 1-, 3-, and 5-year IDI values were 0.10, 0.12, and 0.13 (P < 0.001), respectively. In 1-, 3-, and 5-year CSS prediction using DCA curves, the nomogram outperformed the AJCC staging system. The nomogram performed well in both the internal and external validation cohorts.

CONCLUSION

We developed and validated a nomogram to predict 1-, 3-, and 5-year CSS for GNEC patients after surgical resection. This well-performing model could help doctors enhance the treatment plan.

Pharmacological effects and mechanisms of paeonol on antitumor and prevention of side effects of cancer therapy

Cancer represents one of the leading causes of mortality worldwide. Conventional clinical treatments include radiation therapy, chemotherapy, immunotherapy, and targeted therapy. However, these treatments have inherent limitations, such as multidrug resistance and the induction of short- and long-term multiple organ damage, ultimately leading to a significant decrease in cancer survivors' quality of life and life expectancy. Paeonol, a nature active compound derived from the root bark of the medicinal plant Paeonia suffruticosa, exhibits various pharmacological activities. Extensive research has demonstrated that paeonol exhibits substantial anticancer effects in various cancer, both in vitro and in vivo. Its underlying mechanisms involve the induction of apoptosis, the inhibition of cell proliferation, invasion and migration, angiogenesis, cell cycle arrest, autophagy, regulating tumor immunity and enhanced radiosensitivity, as well as the modulation of multiple signaling pathways, such as the PI3K/AKT and NF-κB signaling pathways. Additionally, paeonol can prevent adverse effects on the heart, liver, and kidneys induced by anticancer therapy. Despite numerous studies exploring paeonol's therapeutic potential in cancer, no specific reviews have been conducted. Therefore, this review provides a systematic summary and analysis of paeonol's anticancer effects, prevention of side effects, and the underlying mechanisms involved. This review aims to establish a theoretical basis for the adjunctive strategy of paeonol in cancer treatment, ultimately improving the survival rate and enhancing the quality of life for cancer patients.

PGAM4 silencing inhibited glycolysis and chemoresistance to temozolomide in glioma cells

Gliomas account for about 80% of malignant brain tumors. The incidence of a new brain tumor is 6.4 per 100,000 persons per year with an overall 5-year survival rate of 33.4%. Regardless of the great advances that have been made in recent years, the causes and pathogenesis of glioma remain unclear. Here we study how phosphoglycerate mutase 4 (PGAM4) contributes to glioma. Using a variety of methods to examine glioma cell viability, proliferation, apoptosis, glycolysis, as well as ChIP coanalysis with modified histone H3, we showed that PGAM4 was significantly upregulated in patients with glioma and associated with poor survival. Silencing PGAM4 attenuated cell viability, proliferation, and glycolysis in T98G cells and suppressed tumor growth in vivo, while overexpressing PGAM4 promoted cell viability, proliferation, and glycolysis in U251 cells via regulating glycolysis pathway. Study also revealed that PGAM4 was regulated by EP300-mediated modifications of H3K27ac. PGAM4 silencing inhibited cell viability and proliferation, suppressed tumor growth, and decreased chemoresistance to temozolomide in glioma cells through suppressing glycolysis.

Mechanisms involved in cancer stem cell resistance in head and neck squamous cell carcinoma

Despite scientific advances in the Oncology field, cancer remains a leading cause of death worldwide. Molecular and cellular heterogeneity of head and neck squamous cell carcinoma (HNSCC) is a significant contributor to the unpredictability of the clinical response and failure in cancer treatment. Cancer stem cells (CSCs) are recognized as a subpopulation of tumor cells that can drive and maintain tumorigenesis and metastasis, leading to poor prognosis in different types of cancer. CSCs exhibit a high level of plasticity, quickly adapting to the tumor microenvironment changes, and are intrinsically resistant to current chemo and radiotherapies. The mechanisms of CSC-mediated therapy resistance are not fully understood. However, they include different strategies used by CSCs to overcome challenges imposed by treatment, such as activation of DNA repair system, anti-apoptotic mechanisms, acquisition of quiescent state and Epithelial-mesenchymal transition, increased drug efflux capacity, hypoxic environment, protection by the CSC niche, overexpression of stemness related genes, and immune surveillance. Complete elimination of CSCs seems to be the main target for achieving tumor control and improving overall survival for cancer patients. This review will focus on the multi-factorial mechanisms by which CSCs are resistant to radiotherapy and chemotherapy in HNSCC, supporting the use of possible strategies to overcome therapy failure.

MASM inhibits cancer stem cell-like characteristics of EpCAM+ cells via AKT/GSK3β/β-catenin signaling

OBJECTIVES

Liver cancer stem cells (LCSCs) are regarded as the frequent cause of hepatocellular carcinoma (HCC) relapse and therapeutic resistance. The epithelial cell adhesion molecule (EpCAM) is one of the key biomarkers for LCSCs. EpCAM⁺ cells from HCC have been reported to display cancer stem cell-like (CSC-like) properties. Therefore, we aimed to verify the effect of MASM, a novel derivative of matrine, on CSC-like properties of EpCAM⁺ HCC cells.

METHODS

EpCAM⁺ cells were isolated from Hep3B and Huh7 cells using the magnetic-activated cell sorting. The capacity for self-renewal and proliferation of EpCAM⁺ HCC cells was determined by the sphere-formation and cell counting kit 8 assays. After these cell populations were exposed to increasing concentrations of MASM, sphere formation, cell proliferation, apoptosis, resistance to chemotherapy and colony formation were evaluated, respectively. Moreover, the stemness-associated gene expression and underlying mechanisms were evaluated by quantitative real-time polymerase chain reaction and sphere-forming assay.

RESULTS

MASM significantly inhibited proliferation without inducing apoptosis, down-regulated the expression of stemness-related genes, decreased the percentage of EpCAM⁺ HCC cells and up-regulated mature hepatocyte-related genes. Moreover, MASM suppressed the formation and reduced the size of not only primary spheroids but also subsequent spheroids. Additionally, our results showed that MASM inhibited the AKT/GSK3β/β-catenin signaling pathway.

CONCLUSION

MASM treatment is effective against EpCAM⁺ cells and may be considered as a novel drug candidate in HCC therapy.

Apigenin Loaded Lipoid-PLGA-TPGS Nanoparticles for Colon Cancer Therapy: Characterization, Sustained Release, Cytotoxicity, and Apoptosis Pathways

Colon cancer (CC) is one of major causes of mortality and affects the socio-economic status world-wide. Therefore, developing a novel and efficient delivery system is needed for CC management. Thus, in the present study, lipid polymer hybrid nanoparticles of apigenin (LPHyNPs) was prepared and characterized on various parameters such as particle size (234.80 ± 12.28 nm), PDI (0.11 ± 0.04), zeta potential (−5.15 ± 0.70 mV), EE (55.18 ± 3.61%), etc. Additionally, the DSC, XRD, and FT-IR analysis determined drug entrapment and affinity with the selected excipient, demonstrating a promising drug affinity with the lipid polymer. Morphological analysis via SEM and TEM exhibited spherical NPs with a dark color core, which indicated drug entrapment inside the core. In vitro release study showed significant (p < 0.05) sustained release of AGN from LPHyNPs than AGN suspension. Further, the therapeutic efficacy in terms of apoptosis and cell cycle arrest of developed LPHyNPs against CC was estimated by performing flow cytometry and comparing its effectiveness with blank LPHyNPs and AGN suspension, which exhibited remarkable outcomes in favor of LPHyNPs. Moreover, the mechanism behind the anticancer attribute was further explored by estimating gene expression of various signaling molecules such as Bcl-2, BAX, NF-κB, and mTOR that were involved in carcinogenic pathways, which indicated significant (p < 0.05) results for LPHyNPs. Moreover, to strengthen the anticancer potential of LPHyNPs against chemoresistance, the expression of JNK and MDR-1 genes was estimated. Outcomes showed that their expression level reduced appreciably when compared to blank LPHyNPs and AGN suspension. Hence, it can be concluded that developed LPHyNPs could be an efficient therapeutic system for managing CC.

RNF7 inhibits apoptosis and sunitinib sensitivity and promotes glycolysis in renal cell carcinoma via the SOCS1/JAK/STAT3 feedback loop

Background

RING finger protein 7 (RNF7) is a highly conserved protein that functions as an E3 ubiquitin ligase. RNF7 overexpression is indicated in multiple human cancers, but its role in renal cell carcinoma (RCC) and the mechanisms underlying how it regulates the initiation and progression of RCC have not been explored.

Methods

Bioinformatics analysis, quantitative reverse-transcription polymerase chain reaction (RT-PCR), and Western blot were conducted to determine the expression of RNF7 in RCC tissues and cell lines. Knockdown and overexpression experiments were performed to examine the effects of RNF7 on cell viability, apoptosis, and glycolysis in vitro and on tumor growth in nude mice in vivo.

Results

The elevated RNF7 expression in tumor tissues of patients with RCC was correlated with poor survival. RNF7 overexpression inhibited apoptosis and promoted glycolysis in vitro and increased tumor growth in vivo by activating the JAK/STAT3 signaling pathway by ubiquitination of SOCS1. Moreover, RNF7 overexpression affected the sensitivity of RCC cells to sunitinib. Finally, STAT3 activation was necessary for transcriptional induction of RNF7.

Conclusion

These results demonstrate that RNF7 inhibited apoptosis, promoted glycolysis, and inhibited sunitinib sensitivity in RCC cells via ubiquitination of SOCS1, thus activating STAT3 signaling. These suggest the potential for targeting the RNF7-SOCS1/JAK/STAT3 pathway for RCC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00337-5.

Modulation of TLR/NF-κB/NLRP Signaling by Bioactive Phytocompounds: A Promising Strategy to Augment Cancer Chemotherapy and Immunotherapy

Background

Tumors often progress to a more aggressive phenotype to resist drugs. Multiple dysregulated pathways are behind this tumor behavior which is known as cancer chemoresistance. Thus, there is an emerging need to discover pivotal signaling pathways involved in the resistance to chemotherapeutic agents and cancer immunotherapy. Reports indicate the critical role of the toll-like receptor (TLR)/nuclear factor-κB (NF-κB)/Nod-like receptor pyrin domain-containing (NLRP) pathway in cancer initiation, progression, and development. Therefore, targeting TLR/NF-κB/NLRP signaling is a promising strategy to augment cancer chemotherapy and immunotherapy and to combat chemoresistance. Considering the potential of phytochemicals in the regulation of multiple dysregulated pathways during cancer initiation, promotion, and progression, such compounds could be suitable candidates against cancer chemoresistance.

Objectives

This is the first comprehensive and systematic review regarding the role of phytochemicals in the mitigation of chemoresistance by regulating the TLR/NF-κB/NLRP signaling pathway in chemotherapy and immunotherapy.

Methods

A comprehensive and systematic review was designed based on Web of Science, PubMed, Scopus, and Cochrane electronic databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to include papers on TLR/NF-κB/NLRP and chemotherapy/immunotherapy/chemoresistance by phytochemicals.

Results

Phytochemicals are promising multi-targeting candidates against the TLR/NF-κB/NLRP signaling pathway and interconnected mediators. Employing phenolic compounds, alkaloids, terpenoids, and sulfur compounds could be a promising strategy for managing cancer chemoresistance through the modulation of the TLR/NF-κB/NLRP signaling pathway. Novel delivery systems of phytochemicals in cancer chemotherapy/immunotherapy are also highlighted.

Conclusion

Targeting TLR/NF-κB/NLRP signaling with bioactive phytocompounds reverses chemoresistance and improves the outcome for chemotherapy and immunotherapy in both preclinical and clinical stages.

HucMSC exosomes promoted imatinib-induced apoptosis in K562-R cells via a miR-145a-5p/USP6/GLS1 axis

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with increasing incidence worldwide. Growing evidence suggests that ubiquitin-specific proteases (USPs) play a role in cancer treatment. Dysregulation of miR-146a has been found in both adult and pediatric patients with acute leukemia. Knockdown of glutaminase-1 (GLS1) resulted in inhibition of tumor growth. However, the role of miR-146a-5p/USP6/GLS1 in leukemia and chemoresistance of leukemia cells remains to be elucidated. In the current study, USP6 level was increased in bone marrow aspiration specimens of patients with CML and associated with poor prognosis. USP6 was significantly upregulated in imatinib (IM)-resistant clinical samples compared with IM-sensitive samples. USP6 overexpression significantly inhibited IM-induced apoptosis of leukemia cells. Overexpressing USP6 significantly increased GLS1 ubiquitination to decrease GLS protein. A mechanism study indicated that USP6 regulation of IM resistance of CML cells was GLS1 dependent and regulated by miR-146a-5p. Administration of human umbilical cord mesenchymal stem cell (hucMSC) exosomes promoted IM-induced cell apoptosis through miR-145a-5p/USP6. Therefore, hucMSC exosomes promoted IM-induced apoptosis of K562-R cells by suppressing GLS1 ubiquitination to increase GLS protein via miR-146a-5p and its target GLS1. The findings highlight the importance of miR-146a-5p/USP6/GLS1 signaling in chemoresistance of leukemia and provide new insights into therapeutic strategies for chemoresistant leukemia.

The multiple faces of NANOG in cancer: a therapeutic target to chemosensitize therapy-resistant cancers

The transcription factor NANOG regulates self-renewal and pluripotency in embryonic cells, and its downregulation leads to cell differentiation. Recent studies have linked upregulation of NANOG in various cancers and the regulation of expression of different molecules, and vice versa, to induce proliferation, metastasis, invasion and chemoresistance. Thus NANOG is an oncogene that functions by inducing stem cells' circuitries and heterogeneity in cancers. Understanding NANOG's role in various cancers may lead to it becoming a therapeutic target to halt cancer progression. The NANOG network can also be targeted to resensitize resistant cancer cells to conventional therapies. The current review focuses on NANOG regulation in the various signaling networks leading to cancer progression and chemoresistance, and highlights the therapeutic aspect of targeting NANOG in various cancers.

Role of NRF2 cascade in determining the differential response of cervical cancer cells to anticancer drugs: an in vitro study

BACKGROUND

Cervical cancers are usually treatable if detected in early stages by a combination of therapies. However, the prognosis of cervical cancer patients with metastasis remains unfavorable due to the fact that most of the cervical carcinomas are either resistant to anticancer drugs or show signs of relapse after initial treatment. Therefore, it is important to control the chemoresistance as it is the key to develop effective treatment options for cervical cancer.

OBJECTIVE

The current study aimed at evaluating the differential responses of cervical cancer cells to anti-cancer drugs and assessed whether the differences in the expression profiles of antioxidant genes regulated by nuclear factor erythroid-2-related factor 2 (NRF2), led to the variations in the sensitivities of the cancer cells to treatment.

METHODOLOGY

Three cervical cancer cell lines were investigated for their differences in NRF2 pathway by measuring the gene expression and enzyme activity. The differences in the sensitivity to anti-cancer drugs and variation in ROS profile was also evaluated. The addition of exogenous drugs to manipulate the intracellular ROS and its effect on NRF2 pathway genes was also investigated.

RESULTS

HeLa and SiHa cells were more sensitive to cisplatin and oxaliplatin treatment than C33A cells. HeLa and SiHa cells had significantly lower NRF2 gene levels, NQO1 enzyme activity and basal GSH levels than C33A cells. Levels of ROS induced were higher in HeLa than C33A cells.

CONCLUSION

Overall, the differences in the cellular levels of antioxidant regulatory genes led to the differential response of cervical cancer cells to anti-cancer drugs.

Battling Chemoresistance in Cancer: Root Causes and Strategies to Uproot Them

With nearly 10 million deaths, cancer is the leading cause of mortality worldwide. Along with major key parameters that control cancer treatment management, such as diagnosis, resistance to the classical and new chemotherapeutic reagents continues to be a significant problem. Intrinsic or acquired chemoresistance leads to cancer recurrence in many cases that eventually causes failure in the successful treatment and death of cancer patients. Various determinants, including tumor heterogeneity and tumor microenvironment, could cause chemoresistance through a diverse range of mechanisms. In this review, we summarize the key determinants and the underlying mechanisms by which chemoresistance appears. We then describe which strategies have been implemented and studied to combat such a lethal phenomenon in the management of cancer treatment, with emphasis on the need to improve the early diagnosis of cancer complemented by combination therapy.

circ_C20orf11 enhances DDP resistance by inhibiting miR-527/YWHAZ through the promotion of extracellular vesicle-mediated macrophage M2 polarization in ovarian cancer

Ovarian cancer is a fatal gynecologic tumor, and conventional treatment is mainly limited by chemoresistance. The mechanism contributing to chemoresistance in ovarian cancer has yet to be established. This study aimed to investigate the specific role of circ_C20orf11 in regulating chemoresistance to cisplatin (DDP)in ovarian cancer. We first established two DDP-resistant ovarian cancer cell lines. Then, we identified the effect of circ_C20orf11 on specific cellular characteristics (proliferation, apoptosis, DDP resistance) via a series of experiments. The binding sites between circ_C20orf11 and miR-527 and between miR-527 and YWHAZ were predicted using a bioinformatics tool and confirmed with a dual-luciferase reporter assay. Furthermore, extracellular vesicles (EVs) derived from DDP-resistant cell lines were identified, and the effect of EVs on macrophage polarization was examined. circ_C20orf11 was upregulated in ovarian cancer. Increased circ_C20orf11 expression enhanced DDP resistance and cell proliferation and reduced cell apoptosis in DDP-resistant cell lines after DDP treatment by sponging miR-527 and promoting YWHAZ expression. In addition, we found that DDP-resistant cell-derived EVs can induce macrophage M2 polarization, whereas silencing of circ_C20orf11 inhibited EV-induced macrophage M2 polarization. Consistent with these results, silencing of circ_C20orf11 enhanced sensitivity to DDP in vivo. Importantly, we proved that circ_C20orf11 expression was upregulated in EVs extracted from the serum of DDP-resistant patients. Our study demonstrated that silencing circ_C20orf11 sensitizes ovarian cancer to DDP by promoting miR-527/YWHAZ signaling and EV-mediated macrophage M2 polarization.

Exosomal miR-21-5p derived from cisplatin-resistant SKOV3 ovarian cancer cells promotes glycolysis and inhibits chemosensitivity of its progenitor SKOV3 cells by targeting PDHA1

Ovarian cancer (OC) is a common reason for gynecologic cancer death. Standard treatments of OC consist of surgery and chemotherapy. However, chemoresistance should be considered. Exosomal miR-21-5p has been shown to regulate the chemosensitivity of cancer cells through regulating pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1). However, the role of miR-21-5p/PDHA1 in OC is unclear. The levels of miR-21-5p and PDHA1 in clinical samples and cells were investigated. Exosomes derived from SKOV3/cisplatin (SKOV3/DDP) cells (DDP-Exos) were isolated and used to treat SKOV3 cells to test DDP-Exos effects on SKOV3 cells. Extracellular acidification rate and oxygen consumption rate were tested with a Seahorse analyzer. Cell apoptosis was analyzed by a flow cytometer. PDHA1 was overexpressed and miR-21-5p was silenced in SKOV3 cells to study the underlying mechanism of miR-21-5p in OC. Quantitative real-time PCR and immunoblots were applied to measure gene expression at mRNA and protein levels. The levels of PDHA1 in DDP-resistant SKOV3 or tumor tissues were significantly decreased while the levels of miR-21-5p were remarkably upregulated. miR-21-5p in DDP-Exos was sharply increased compared to that of Exos. Data also indicated that DDP-Exos treatment suppressed the sensitivity of SKOV3 cells to DDP and promoted cell viability and glycolysis of SKOV3 cells through inhibiting PDHA1 by exosomal miR-21-5p. miR-21-5p derived from DDP-resistant SKOV3 OC cells promotes glycolysis and inhibits chemosensitivity of its progenitor SKOV3 cells by targeting PDHA1. Our data highlights the important role of miR-21-5p/PDHA1 axis in OC and sheds light on new therapeutic development.

Synergistic anti-cancer action of salicylic acid and cisplatin on HeLa cells elucidated by network pharmacology and in vitro analysis

AIM

To investigate the anti-cancer potential of salicylic acid and cisplatin combination in HeLa cells and the underlying mechanism.

MAIN METHODS

Drugs and disease targets were extracted from DrugBank, BATMAN-TCM, STITCH, PharmMapper and Comparative Toxigenomics Database. Cytoscape 3.8.2 was used to merge the protein-protein interaction networks and select core targets. GO and KEGG analysis was done using Metascape and WebGestalt. Effect of salicylic acid and cisplatin alone and in combination on cells viability was studied by MTT assay. The type of interaction between salicylic acid and cisplatin was determined by CompuSyn. Apoptosis was evaluated by molecular docking, Rhodamine-123, DAPI, AO/EtBr staining, flow cytometry, qRT-PCR and western blotting. Metastasis was studied using scratch assay and western blotting. UHRF1 transient silencing was performed by siRNA.

KEY FINDINGS

Out of 420, 1863 and 1362 respective targets of salicylic acid, cisplatin and cervical cancer, 18 core proteins were enriched in apoptosis and cell migration related pathways. IC50 value of cisplatin was reduced by 14 fold in combination with salicylic acid at IC20 (4 μM). There was loss of mitochondrial membrane potential and downregulation of UHRF1, pAkt, full length PARP and pro-caspase 3 expression. Transient silencing of UHRF1 also induced mitochondrial depolarization and apoptosis. The combination also exhibited anti-metastasis effect as it suppressed migration, upregulated PAX1 and downregulated MMP-2.

SIGNIFICANCE

Reduction in cisplatin concentration, enhanced anti-cancer effects and UHRF1 downregulation due to synergistic interaction between salicylic acid and cisplatin underscores the therapeutic importance of the combination to overcome chemo-resistance and side effects of cisplatin.

Magnetic Particles with Polymeric Shells Bearing Cholesterol Moieties Sensitize Breast Cancer Cells to Low Doses of Doxorubicin

One of the promising strategies for improvement of cancer treatment is application of a combination therapy. The aim of this study was to investigate the anticancer activity of nanoformulations containing doxorubicin and iron oxide particles covered with polymeric shells bearing cholesterol moieties. It was postulated that due to high affinity to cell membranes, particles comprising poly(cholesteryl acrylate) can sensitize cancer cells to doxorubicin chemotherapy. The performed analyses revealed that the developed systems are effective against the human breast cancer cell lines MCF-7 and MDA-MB-231 even at low doses of the active compound applied (0.5 µM). Additionally, high compatibility and lack of toxicity of the tested materials against human red blood cells, immune (monocytic THP-1) cells, and cardiomyocyte H9C2(2-1) cells was demonstrated. Synergistic effects observed upon administration of doxorubicin with polymer–iron oxide hybrids comprising poly(cholesteryl acrylate) may provide an opportunity to limit toxicity of the drug and to improve its therapeutic efficiency at the same time.

Prothymosin α promotes colorectal carcinoma chemoresistance through inducing lipid droplet accumulation

Colorectal cancer (CRC) affects millions of people worldwide. Chemoresistance seriously impairs the therapeutic effects. Lipid droplets (LDs) abnormally accumulate in CRC supported chemoresistance. Exploring the mechanism of LD-induced chemoresistance is extremely important for improving prognosis of CRC patients. The expression of PTMA was increased in both CRC tissues and cells, which was positively correlated with LD production. PTMA facilitated chemoresistance to gemcitabine by inducing LD production in CRC cells. PTMA enhanced LD biogenesis and chemoresistance to gemcitabine by promoting SREBP-1-mediated lipogenesis and STAT3 activation in CRC.

Two Faces of Autophagy in the Struggle against Cancer

Autophagy can play a double role in cancerogenesis: it can either inhibit further development of the disease or protect cells, causing stimulation of tumour growth. This phenomenon is called "autophagy paradox", and is characterised by the features that the autophagy process provides the necessary substrates for biosynthesis to meet the cell's energy needs, and that the over-programmed activity of this process can lead to cell death through apoptosis. The fight against cancer is a difficult process due to high levels of resistance to chemotherapy and radiotherapy. More and more research is indicating that autophagy may play a very important role in the development of resistance by protecting cancer cells, which is why autophagy in cancer therapy can act as a "double-edged sword". This paper attempts to analyse the influence of autophagy and cancer stem cells on tumour development, and to compare new therapeutic strategies based on the modulation of these processes.

Chemoresistance in Ovarian Cancer: Prospects for New Drugs

This review focuses on the conventional treatment, signaling pathways and various reasons for drug resistance with an understanding of novel methods that can lead to effective therapies. Ovarian cancer is amongst the most common gynecological and lethal cancers in women affecting different age groups (20-60). The survival rate is limited to 5 years due to diagnosis in subsequent stages with a reoccurrence of tumor and resistance to chemotherapeutic therapy. The recent clinical trials use the combinatorial treatment of carboplatin and paclitaxel on ovarian cancer after the cytoreduction of the tumor. Predominantly, patients are responsive initially to therapy and later develop metastases due to drug resistance. Chemotherapy also leads to drug resistance causing enormous variations at the cellular level. Multifaceted mechanisms like drug resistance are associated with a number of genes and signaling pathways that process the proliferation of cells. Reasons for resistance include epithelial-mesenchyme, DNA repair activation, autophagy, drug efflux, pathway activation, and so on. Determining the routes on the molecular mechanism that target chemoresistance pathways are necessary for controlling the treatment and understanding efficient drug targets can open light on improving therapeutic outcomes. The most common drug used for ovarian cancer is Cisplatin that activates various chemoresistance pathways, ultimately causing drug resistance. There have been substantial improvements in understanding the mechanisms of cisplatin resistance or chemo sensitizing cisplatin for effective treatment. Therefore, using therapies that involve a combination of phytochemical or novel drug delivery system would be a novel treatment for cancer. Phytochemicals are plant-derived compounds that exhibit anti-cancer, anti-oxidative, anti-inflammatory properties and reduce side effects exerted by chemotherapeutics.

Elucidation of underlying molecular mechanism of 5-Fluorouracil chemoresistance and its restoration using fish oil in experimental colon carcinoma

Latest strategies for cancer treatment primarily focus on the use of chemosensitizers to enhance therapeutic outcome. N-3 PUFAs have emerged as the strongest candidate for the prevention of colorectal cancer (CRC). Our previous studies have demonstrated that fish oil (FO) rich in n-3 PUFAs not only increased therapeutic potential of 5-Fluorouracil(5-FU) in colon cancer but also ameliorated its toxicity. Henceforth, the present study is designed to elucidate mechanistic insights of FO as a chemosensitizer to circumvent drug resistance in experimental colon carcinoma. The colon cancer was induced by 1,2-dimethylhydrazine(DMH)/dextran sulfate sodium(DSS) in male Balb/c mice and these animals were treated with 5-FU(12.5 mg/kg b.w.), FO(0.2 ml), or 5-FU + FO(12.5 mg/kg b.w + 0.2 ml) orally for 14 days. The molecular mechanism of overcoming 5-FU resistance using FO in colon cancer was delineated by estimating expression of cancer stem cell markers using flowcytometric method and drug transporters by immunohistochemistry and immunoblotting. Additionally, distribution profile of 5-FU and its cytotoxic metabolite, 5-FdUMP at target(colon), and non-target sites (serum, kidney, liver, spleen) was assessed using high-performance liquid chromatography(HPLC) method. The observations revealed that expression of CSCs markers was remarkably reduced after using fish oil along with 5-FU in carcinogen-treated animals. Interestingly, the use of FO alongwith 5-FU also significantly declined the expression of drug transporters (ABCB1,ABCC5) and consequently resulted in an increased cellular uptake of 5-FU and its metabolite, 5-FdUMP at target site (colon). It could be possibly associated with change in permeability of cell membrane owing to the alteration in membrane fluidity. The present study revealed the mechanistic insights of FO as a MDR revertant which successfully restored 5-FU-mediated chemoresistance in experimental colon carcinoma.

Hypoxia Dictates Metabolic Rewiring of Tumors: Implications for Chemoresistance

Hypoxia is a condition commonly observed in the core of solid tumors. The hypoxia-inducible factors (HIF) act as hypoxia sensors that orchestrate a coordinated response increasing the pro-survival and pro-invasive phenotype of cancer cells, and determine a broad metabolic rewiring. These events favor tumor progression and chemoresistance. The increase in glucose and amino acid uptake, glycolytic flux, and lactate production; the alterations in glutamine metabolism, tricarboxylic acid cycle, and oxidative phosphorylation; the high levels of mitochondrial reactive oxygen species; the modulation of both fatty acid synthesis and oxidation are hallmarks of the metabolic rewiring induced by hypoxia. This review discusses how metabolic-dependent factors (e.g., increased acidification of tumor microenvironment coupled with intracellular alkalinization, and reduced mitochondrial metabolism), and metabolic-independent factors (e.g., increased expression of drug efflux transporters, stemness maintenance, and epithelial-mesenchymal transition) cooperate in determining chemoresistance in hypoxia. Specific metabolic modifiers, however, can reverse the metabolic phenotype of hypoxic tumor areas that are more chemoresistant into the phenotype typical of chemosensitive cells. We propose these metabolic modifiers, able to reverse the hypoxia-induced metabolic rewiring, as potential chemosensitizer agents against hypoxic and refractory tumor cells.

Therapy-induced chemoexosomes: Sinister small extracellular vesicles that support tumor survival and progression

Chemotherapy involves the use of multiple cytotoxic or cytostatic drugs acting by various mechanisms to kill or arrest the growth of cancer cells. Chemotherapy remains the most utilized approach for controlling cancer. Emerging evidence indicates that cancer cells activate various pro-survival mechanisms to cope with chemotherapeutic stress. These mechanisms persist during treatment and often help orchestrate tumor regrowth and patient relapse. Exosomes due to their nature of carrying and transferring multiple biologically active components have emerged as key players in cancer pathogenesis. Recent data demonstrates that chemotherapeutic stress enhances the secretion and alters the cargo carried by exosomes. These altered exosomes, which we refer to as chemoexosomes, are capable of transferring cargo to target tumor cells that can enhance their chemoresistance, increase their metastatic behavior and in certain cases even aid in endowing tumor cells with cancer stem cell-like properties. This mini-review summarizes the recent developments in our understanding of the impact chemoexosomes have on tumor survival and progression.

Epigenetic modifications of c-MYC: Role in cancer cell reprogramming, progression and chemoresistance

Both genetic and epigenetic mechanisms intimately regulate cancer development and chemoresistance. Different genetic alterations are observed in multiple genes, and most are irreversible. Aside from genetic alterations, epigenetic alterations play a crucial role in cancer. The reversible nature of epigenetic modifications makes them an attractive target for cancer prevention and therapy. Specific epigenetic alteration is also being investigated as a potential biomarker in multiple cancers. c-MYC is one of the most important transcription factors that are centrally implicated in multiple types of cancer cells reprogramming, proliferation, and chemoresistance. c-MYC shows not only genetic alterations but epigenetic changes in multiple cancers. It has been observed that epigenome aberrations can reversibly alter the expression of c-MYC, both transcriptional and translational levels. Understanding the underlying mechanism of the epigenetic alterations of c-MYC, that has its role in multiple levels of cancer pathogenesis, can give a better understanding of various unresolved questions regarding cancer. Recently, some researchers reported that targeting the epigenetic modifiers of c-MYC can successfully inhibit cancer cell proliferation, sensitize the chemoresistant cells, and increase the patient survival rate. As c-MYC is an important transcription factor, epigenetic therapy might be one of the best alternatives for the conventional therapies that assumes the "one-size-fits-all" role. It can also increase the precision of targeting and enhance the effectiveness of treatments among various cancer subtypes. In this review, we highlighted the role of epigenetically modified c-MYC in cancer cell reprogramming, progression, and chemoresistance. We also summarize the potential therapeutic approaches to target these modifications for the prevention of cancer development and chemoresistant phenotypes.

Fluoroquinolones as a potentially novel class of antidiabesity and antiproliferative compounds: synthesis and docking studies

Intense efforts by the pharmaceutical industry have been made to identify new targets for obesity diabetes (diabesity). Pancreatic triacylglycerol lipase (PL) inhibition is an interesting putative target for obesity management. Fluoroquinolones (FQs) have been identified as potent inhibitors of PL. The aim of this research was to synthesize novel FQs and evaluate their in vitro antilipolytic and antiproliferative properties. Characterization of the synthesized FQs was carried out with NMR, MS, IR, and EA. Like orlistat, potential FQs’ modulation of PL was quantified colorimetrically (n = 3) and was further supported by docking studies. Compared with cisplatin, FQs’ antiproliferative propensities against a panel of obesity related colorectal cancer cell lines were investigated with Sulforhodamine B assay. Twelve novel FQs (2A–5A, 2B–5B, and 2C–5C) were synthesized and characterized. The PL-IC50 values of tested FQs were in the range of 6.8–165.7 μmol/L. FQ 4A was the most active antiproliferative compound against HCT116 with an IC50 value of 3.5 μmol/L. Their selectivity of growth inhibition for safety examination using normal periodontal ligament fibroblasts (PDL) in comparison with cisplatin’s lack of differential cytotoxicity was reported. Lipophilicity and hydrogen bonding were found essential for both activities. Conclusively, FQs are robustly proven for their emerging in vitro anti-obesity and antiproliferative activities.

Exploration of gastric neuroendocrine carcinoma (GNEC) specific signaling pathways involved in chemoresistance via transcriptome and in vitro analysis

Gastric neuroendocrine carcinoma (GNEC) is rare cancer detected in the stomach. Previously, we demonstrated that the poorer prognosis of GNEC patients compared with gastric adenocarcinoma (GAC) patients was probably due to the lack of response to chemotherapy. Thus, it is crucial to study the specific GNEC gene expression pattern and investigate chemoresistance mechanism of GNEC. The transcriptome of GNEC patients was compared with that of GAC patients using RNA-seq. The KEGG analysis was employed to explore the specific differential expression gene function enrichment pattern. In addition, the transcriptomes of two GNEC cell lines, ECC10 and ECC12, were also compared with those of two GAC cell lines, MGC-803 and AGS, using RNA-seq. Comparing patient samples and cell lines transcriptome data, we try to uncover the potential targets and pathways which may affect the chemoresistance of GNEC. By combing all transcriptome data, we identified 22 key genes that were specifically up-regulated in GNEC. This panel of genes probably involves in the chemoresistance of GNEC. From our current experimental data, NeuroD1, one of the 22 genes, is associated with the prognosis of GNEC patients. Knockdown of NeuroD1 enhanced the sensitivity to irinotecan of GNEC cell lines. Our research sheds light in identifying a panel of novel therapeutic target specifically for GNEC clinical treatment which has not been reported before.

Dysregulated Phosphorylation of p53, Autophagy and Stemness Attributes the Mutant p53 Harboring Colon Cancer Cells Impaired Sensitivity to Oxaliplatin

Colorectal cancer (CRC) forms one of the highest ranked cancer types in the world with its increasing incidence and mortality rates despite the advancement in cancer therapeutics. About 50% of human CRCs are reported to have defective p53 expression resultant of TP53 gene mutation often contributing to drug resistance. The current study was aimed to investigate the response of wild-type TP53 harboring HCT 116 and mutant TP53 harboring HT 29 colon cancer cells to chemotherapeutic drug oxaliplatin (OX) and to elucidate the underlying molecular mechanisms of sensitivity/resistance in correlation to their p53 status. OX inhibited growth of wild-type p53-harboring colon cancer cells via p53/p21-Bax mediated apoptosis. Our study revealed that dysregulated phosphorylation of p53, autophagy as well as cancer stemness attributes the mutant p53-harboring colon cancer cells impaired sensitivity to OX.

Evolution of the Experimental Models of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare, aggressive disease with poor overall survival. In advanced cases, surgery is often not possible or fails; in addition, there is a lack of effective and specific therapies. Multidisciplinary approaches and advanced technologies have improved the knowledge of CCA molecular pathogenesis, highlighting its extreme heterogeneity and high frequency of genetic and molecular aberrations. Effective preclinical models, therefore, should be based on a comparable level of complexity. In the past years, there has been a consistent increase in the number of available CCA models. The exploitation of even more complex CCA models is rising. Examples are the use of CRISPR/Cas9 or stabilized organoids for in vitro studies, as well as patient-derived xenografts or transgenic mouse models for in vivo applications. Here, we examine the available preclinical CCA models exploited to investigate: (i) carcinogenesis processes from initiation to progression; and (ii) tools for personalized therapy and innovative therapeutic approaches, including chemotherapy and immune/targeted therapies. For each model, we describe the potential applications, highlighting both its advantages and limits.

Stable Isotope Tracing Metabolomics to Investigate the Metabolic Activity of Bioactive Compounds for Cancer Prevention and Treatment

A major hallmark of cancer is the metabolic reprogramming of cancer cells to fuel tumor growth and proliferation. Various plant-derived bioactive compounds efficiently target the metabolic vulnerabilities of cancer cells and exhibit potential as emerging therapeutic agents. Due to their safety and common use as dietary components, they are also ideal for cancer prevention. However, to render their use as efficient as possible, the mechanism of action of these phytochemicals needs to be well characterized. Stable isotope tracing is an essential technology to study the molecular mechanisms by which nutraceuticals modulate and target cancer metabolism. The use of positionally labeled tracers as exogenous nutrients and the monitoring of their downstream metabolites labeling patterns enable the analysis of the specific metabolic pathway activity, via the relative production and consumption of the labeled metabolites. Although stable isotope tracing metabolomics is a powerful tool to investigate the molecular activity of bioactive compounds as well as to design synergistic nutraceutical combinations, this methodology is still underutilized. This review aims to investigate the research efforts and potentials surrounding the use of stable isotope tracing metabolomics to examine the metabolic alterations mediated by bioactive compounds in cancer.

Spheroid-Based Approach to Assess the Tissue Relevance of Analysis of Dispersed-Settled Tissue Cells by Cytometry of the Reaction Rate Constant

Cytometry of Reaction Rate Constant (CRRC) uses time-lapse fluorescence microscopy to measure a rate constant of a catalytic reaction in individual cells and, thus, facilitate accurate size determination for cell subpopulations with distinct efficiencies of this reaction. Reliable CRRC requires uniform exposure of cells to the reaction substrate followed by their uniform imaging, which in turn, requires that a tissue sample be disintegrated into a suspension of dispersed cells, and these cells settle on the support surface before being analyzed by CRRC. We call such cells "dispersed-settled" to distinguish them from cells cultured as a monolayer. Studies of the dispersed-settled cells can be tissue-relevant only if the cells maintain their 3D tissue state during the multi-hour CRRC procedure. Here, we propose an approach for assessing tissue relevance of the CRRC-based analysis of the dispersed-settled cells. Our approach utilizes cultured multicellular spheroids as a 3D cell model and cultured cell monolayers as a 2D cell model. The CRRC results of the dispersed-settled cells derived from spheroids are compared to those of spheroids and monolayers in order to find if the dispersed-settled cells are representative of the spheroids. To demonstrate its practical use, we applied this approach to a cellular reaction of multidrug resistance (MDR) transport, which was followed by extrusion of a fluorescent substrate from the cells. The approach proved to be reliable and revealed long-term maintenance of MDR transport in the dispersed-settled cells obtained from cultured ovarian cancer spheroids. Accordingly, CRRC can be used to determine accurately the size of a cell subpopulation with an elevated level of MDR transport in tumor samples, which makes CRRC a suitable method for the development of MDR-based predictors of chemoresistance. The proposed spheroid-based approach for validation of CRRC is applicable to other types of cellular reactions and, thus, will be an indispensable tool for transforming CRRC from an experimental technique into a practical analytical tool.

Exosome mediated miR-155 delivery confers cisplatin chemoresistance in oral cancer cells via epithelial-mesenchymal transition

Cisplatin is used as chemotherapeutic drug for oral squamous cell carcinoma (OSCC). However, OSCC cells develop resistance following long-term cisplatin exposure. Resistance against cisplatin chemo-therapy is accredited to the process of epithelial-to-mesenchymal transition, which in-turn has been linked to tumor-recurrence. miRNA deregulation, a common event in cancer, plays contributory role in chemo-resistance. Exosomes acts as the natural cargo for miRNA and facilitates inter-cell communication in the tumor micro-environment. Hence, exosomal-mediated miRNA transference may play essential role in drug resistance and serve as a target for cancer-therapy. miR-155 upregulation in OSCC has been described, however, its relevance in the observed chemo-resistance is unclear and also, if exosomes have any role in miR-155 regulation remain elusive. In the present study, we document for the first time the critical role of exosomes in mediating increments in miR-155 expression in OSCC cells that have acquired cisplatin resistance (cisRes cells). Importantly, exosomal transfer from cisRes to the cisplatin sensitive (cisSens) cells was found to confer significant miR-155 induction in the recipient cisSens cells. Restoration of miR-155 expression in cisSens cells following miR-155 mimics treatment led to epithelial to mesenchymal transition, enhancements in their migratory potential as well as acquisition of resistant phenotype. Notably, similar augmentations in the migratory and chemo-resistant traits were seen upon delivery of exosomes from cisRes to the recipient cisSens cells. Overall, our findings establish the significance of exosomal-mediated miR-155 shuttling in the cisplatin-chemoresistance, commonly observed in OSCC cells, thereby providing rationale for targeting miR-155 signalling for oral cancer therapy.

Cell deformation and acquired drug resistance: elucidating the major influence of drug-nanocarrier delivery systems

Cancer diagnosis and its stage-wise assessment are determined through invasive solid tissue biopsies. Conversely, cancer imaging is enriched through emission tomography and longitudinal high-resolution analysis for the early detection of cancer through altered cell morphology and cell-deformation. Similarly, in post multiple chemo-cycle exposures, the tumor regression and progression thereafter are not well understood. Here, we report chemo-cycles of doxorubicin (Dox) carrying nanoparticles (NPs) to be highly indicative of cell deformation and a progressive indicator of phenotypic expressions of acquired drug resistance (ADR). We designed graphene (G) based nanocarriers by chemically conjugating multiple components: (i) G; (ii) iron oxide (Fe3O4) NPs; and (iii) Dox through a cysteine (Cys) linker (G-Dox and G-Cys-Fe3O4-Dox). Although Dox underwent cell diffusion, the G-based nanocarriers followed a receptor-mediated endocytosis which created a profound impact on the cell membrane integrity. ADR owing to Dox and G-based nanocarriers was analyzed through a cytotoxicity assay, cell morphology deformation parameters and cellular uptake kinetic patterns. Interestingly, after the third chemo-cycle, G-Dox incubated cells showed the greatest decrease in the alteration of the nuclear surface area (NSA) of ∼28%, a ∼40% reduction of the cell surface area (CSA) and a ∼32% increase in the cell roundness (CRd). Our results suggested that the G-based nanocarriers induced the cell deformation process, subsequently resulting in ADR. Although the G-based nanocarriers initiated ADR, G-Dox was most cytotoxic to cancer cells and induced the maximum cell morphology deformation within our scope of study. This outcome implies caution is needed when using G-based nanocarriers and other multi-component nanosystems for Dox delivery as they lead to possible phenotypic expressions of drug resistance in cancer cells.

Metabolic Symbiosis in Chemoresistance: Refocusing the Role of Aerobic Glycolysis

Cellular metabolic reprogramming is now recognized as a hallmark of tumors. Altered tumor metabolism determines the malignant biological behaviors and phenotypes of cancer. More recently, studies have begun to reveal that cancer cells generally exhibit increased glycolysis or oxidative phosphorylation (OXPHOS) for Adenosine Triphosphate(ATP)generation, which is frequently associated with drug resistance. The metabolism of drug-resistant cells is regulated by the PI3K/AKT/mTOR pathway which ultimately confer cancer cells drug resistance phenotype. The key enzymes involved in glycolysis and the key molecules in relevant pathways have been used as targets to reverse drug resistance. In this review, we highlight our current understanding of the role of metabolic symbiosis in therapeutic resistance and discuss the ongoing effort to develop metabolic inhibitors as anti-cancer drugs to overcome drug resistance to classical chemotherapy.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

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

Establishment and Characterization of a New Intrahepatic Cholangiocarcinoma Cell Line Resistant to Gemcitabine

Intrahepatic cholangiocarcinoma (ICC) is one of the most lethal liver cancers. Late diagnosis and chemotherapy resistance contribute to the scarce outfit and poor survival. Resistance mechanisms are still poorly understood. Here, we established a Gemcitabine (GEM) resistant model, the MT-CHC01R1.5 cell line, obtained by a GEM gradual exposure (up to 1.5 µM) of the sensitive counterpart, MT-CHC01. GEM resistance was irreversible, even at high doses. The in vitro and in vivo growth was slower than MT-CHC01, and no differences were highlighted in terms of migration and invasion. Drug prediction analysis suggested that Paclitaxel and Doxycycline might overcome GEM resistance. Indeed, in vitro MT-CHC01R1.5 growth was reduced by Paclitaxel and Doxycycline. Importantly, Doxycycline pretreatment at very low doses restored GEM sensitivity. To assess molecular mechanisms underlying the acquisition of GEM resistance, a detailed analysis of the transcriptome in MT-CHC01R1.5 cells versus the corresponding parental counterpart was performed. Transcriptomic analysis showed that most up-regulated genes were involved in cell cycle regulation and in the DNA related process, while most down-regulated genes were involved in the response to stimuli, xenobiotic metabolism, and angiogenesis. Furthermore, additional panels of drug resistance and epithelial to mesenchymal transition genes (n = 168) were tested by qRT-PCR and the expression of 20 genes was affected. Next, based on a comparison between qRT-PCR and microarray data, a list of up-regulated genes in MT-CHC01R1.5 was selected and further confirmed in a primary cell culture obtained from an ICC patient resistant to GEM. In conclusion, we characterized a new GEM resistance ICC model that could be exploited either to study alternative mechanisms of resistance or to explore new therapies.

The MicroRNA-551a/MEF2C Axis Regulates the Survival and Sphere Formation of Cancer Cells in Response to 5-Fluorouracil

microRNAs regulate a diverse spectrum of cancer biology, including tumorigenesis, metastasis, stemness, and drug resistance. To investigate miRNA-mediated regulation of drug resistance, we characterized the resistant cell lines to 5-fluorouracil by inducing stable expression of miRNAs using lenti-miRNA library. Here, we demonstrate miR-551a as a novel factor regulating cell survival after 5-FU treatment. miR-551a-expressing cells (Hep3B-lenti-miR-551a) were resistant to 5-FU-induced cell death, and after 5-FU treatment, and showed significant increases in cell viability, cell survival, and sphere formation. It was further shown that myocyte-specific factor 2C is the direct target of miR-551a. Our results suggest that miR-551a plays a novel function in regulating 5-FU-induced cell death, and targeting miR-551a might be helpful to sensitize cells to anti-cancer drugs.

Tumor-stromal crosstalk in pancreatic cancer and tissue fibrosis

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with high morbidity and mortality worldwide. To date, limited therapeutic achievements targeting cell proliferation and related mechanisms has led researchers to focus on the microenvironment where pancreatic cancers develop. The anomalous proliferation of stromal cells, such as pancreatic stellate cells, and an increased deposition of altered matrix proteins create an environment that facilitates tumor growth, metastasis and drug resistance. Here, we summarize our understanding of recent advances in research about the role of fibrosis in pancreatic cancer progression, with particular emphasize on the involvement of fibrotic machineries such as wound healing, extra cellular matrix degradation, and epithelial-to-mesenchymal transition. The precise influence of these mechanisms on the biological behaviors and growth of cancer cells has great impact on clinical therapy and therefore deserves more attention. We also discuss the role of various stromal components in conferring drug resistance to PDAC which further worsening the pessimistic disease prognosis. A more in depth understanding of cancer-stroma crosstalk within the tumor microenvironment and stroma based clinical and translational therapies may provide new therapeutic strategies for the prevention of pancreatic cancer progression.

Salvianolic acid B reverses multidrug resistance in nude mice bearing human colon cancer stem cells

Salvianolic acid B (SalB) is a water-soluble phenolic compound, extractable from Salvia miltiorrhiza, and has previously been demonstrated to reverse tumor multidrug resistance (MDR) in colon cancer cells. Cancer stem cells (CSCs) are closely associated with drug resistance. Therefore, establishing a nude mouse model bearing human colon CSCs is important for the study of the mechanisms underlying colon cancer drug resistance as well as the reversal of drug resistance. The present study aimed to establish a nude mouse model bearing human colon CSCs and to investigate the effects of SalB on the drug resistance exhibited by the nude mouse model as well as determine its underlying mechanism. Cells from two colon cancer cell lines (LoVo and HCT-116) were cultured in serum-free medium to obtain CSCs-enriched spheroid cells. Following this, nude mice were transplanted with LoVo and HCT-116 colon CSCs to establish the CSC nude mouse model, which was subsequently demonstrated to exhibit MDR. The results of the present study revealed that following treatment with SalB, the chemotherapeutic drug resistance of xenografts was reversed to a certain extent. Western blot analysis was performed to investigate the expression levels of cluster of differentiation (CD)44, CD133, transcription factor sox-2 (SOX2) and ATP-binding cassette sub-family G member 2 (ABCG2) proteins, and the results demonstrated that treatment with SalB downregulated the expression of CD44, SOX2 and ABCG2 proteins in both LoVo and HCT-116 colon CSCs xenografts. In conclusion, the results of the present study revealed that a serum-free suspension method can be performed to successfully isolate colon CSCs. In addition, a nude mice bearing colon CSCs animal model was successfully established, and associated tumors were confirmed to exhibit MDR. Furthermore, SalB was demonstrated to successfully reverse MDR in nude mice bearing LoVo and HCT-116 colon CSCs, as well as suppress the expression of CD44, SOX2 and ABCG2 proteins.