CENPN suppresses autophagy and increases paclitaxel resistance in nasopharyngeal carcinoma cells by inhibiting the CREB-VAMP8 signaling axis

Chemotherapeutic resistance is one of the most common reasons for poor prognosis of patients with nasopharyngeal carcinoma (NPC). We found that CENPN can promote the growth, proliferation and apoptosis resistance of NPC cells, but its relationship with chemotherapeutic resistance in NPC is unclear. Here we verified that the CENPN expression level in NPC patients was positively correlated with the degree of paclitaxel (PTX) resistance and a poor prognosis through analysis of clinical cases. VAMP8 expression was significantly increased after knockdown of CENPN by transcriptome sequencing. We found in cell experiments that CENPN inhibited macroautophagy/autophagy and VAMP8 expression and significantly increased PTX resistance. Overexpression of CENPN reduced the inhibitory effects of PTX on survival, cell proliferation, cell cycle progression and apoptosis resistance in NPC cells by inhibiting autophagy. In turn, knockdown of CENPN can affect the phenotype of NPC cells by increasing autophagy to achieve PTX sensitization. Sequential knockdown of CENPN and VAMP8 reversed the PTX-sensitizing effect of CENPN knockdown alone. Experiments in nude mice confirmed that knockdown of CENPN can increase VAMP8 expression, enhance autophagy and increase the sensitivity of NPC cells to PTX. Mechanistic studies showed that CENPN inhibited the translocation of p-CREB into the nucleus of NPC cells, resulting in the decreased binding of p-CREB to the VAMP8 promoter, thereby inhibiting the transcription of VAMP8. These results demonstrate that CENPN may be a marker for predicting chemotherapeutic efficacy and a potential target for inducing chemosensitization to agents such as PTX.Abbreviations: 3-MA: 3-methyladenine; ATG5: autophagy related 5; CENPN: centromere protein N; CQ: chloroquine; CREB: cAMP responsive element binding protein; ChIP: chromatin immunoprecipitation assay; IC50: half-maximal inhibitory concentration; LAMP2A: lysosomal associated membrane protein 2A; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NPC: nasopharyngeal carcinoma; NPG: nasopharyngitis; oeCENPN: overexpressed CENPN; PTX: paclitaxel; RAPA: rapamycin; RNA-seq: transcriptome sequencing; shCENPN: small hairpin RNA expression vector targeting the human CENPN gene; shCENPN-shVAMP8: sequential knockdown targeting the human CENPN gene and VAMP8 gene; shVAMP8: small hairpin RNA expression vector targeting the human VAMP8 gene; TEM: transmission electron microscopy; TIR: tumor inhibitory rate; VAMP8: vesicle associated membrane protein 8.

Cancer cell seeding density as a mechanism of chemotherapy resistance: a novel cancer cell density index based on IC50-Seeding Density Slope (ISDS) to assess chemosensitivity

Although the 50% inhibitory concentration (IC50) is a commonly used measurement of chemosensitivity in cancer cells, it has been known to vary with the density of the treated cells (in that more densely seeded cells are more resistant to chemotherapeutic agents). Indeed, density-dependent chemoresistance may be a significant independent mechanism of therapy resistance. We examine the nature of cell density-dependent chemoresistance and explore possible underlying mechanisms. CellTiter-Glo assays and ethidium homodimer staining revealed that response to chemotherapy is density-dependent in all cancer cell lines tested. Our results prompted us to develop a novel cancer cell seeding density index of chemosensitivity, the ISDS (IC50-Seeding Density Slope), which we propose can serve as an improved method of analyzing how cancer cells respond to chemotherapeutic treatment compared to the widely-used IC50. Furthermore, western blot analysis suggests that levels of autophagy and apoptotic markers are modulated by cancer cell density. Cell viability experiments using the autophagy inhibitor chloroquine showed that chloroquine's efficacy was reduced at higher cell densities and that chloroquine and cisplatin exhibited synergy at both higher and lower cell densities in TOV-21G cells. We discuss alternative mechanisms of density-dependent chemoresistance and in vivo/clinical applications, including challenges of adjuvant chemotherapy and minimal residual disease. Taken together, our findings show that cell density is a significant contributor in shaping cancer chemosensitivity, that the ISDS (aka the Ujwal Punyamurtula/Wafik El-Deiry or Ujwal-WAF Index) can be used to effectively assess cell viability and that this phenomenon of density-dependent chemoresistance may be leveraged for a variety of biologic and cancer therapeutic applications.

The kinesin-14 family motor protein KIFC2 promotes prostate cancer progression by regulating p65

The kinesin-14 motor proteins play important roles in tumor development and drug resistance and have been reported as potential biomarkers or therapeutic targets for tumor treatment. However, kinesin family member C2 (KIFC2), one of the kinesin-14 motor family members, remains largely unknown in prostate cancer (PCa) progression. Here, we used the GEO and The Cancer Genome Atlas datasets, Western blotting, and immunohistochemistry analyses to detect KIFC2 expression in PCa tissues. Additionally, a series of in vivo and in vitro experiments were utilized to demonstrate the roles of KIFC2 in PCa cells. We found that KIFC2 was highly expressed and positively correlated with the clinicopathological characteristics in PCa. Functional experiments indicated that KIFC2 could promote PCa progression. Furthermore, we performed an analysis of the KEGG and GSEA databases, subcellular fractionation, and immunofluorescence to investigate the potential mechanisms of KIFC2 in PCa. We confirmed that KIFC2 could regulate the NF-κB pathway via mediating NF-κB p65 protein expression and nuclear translocation thereby promoting PCa progression and chemotherapeutic resistance. Together, our results suggest that KIFC2 is overexpressed in PCa. By regulating the NF-κB pathway, KIFC2 may play a crucial role in PCa.

Cuproptosis enhances docetaxel chemosensitivity by inhibiting autophagy via the DLAT/mTOR pathway in prostate cancer

Cuproptosis, a newly discovered programmed cell death induced by copper ions, is associated with the progression and drug resistance of various tumors. Docetaxel plays a vital role as a first-line chemotherapeutic agent for advanced prostate cancer; however, most patients end up with prostate cancer progression because of inherent or acquired resistance. Herein, we examined the role of cuproptosis in the chemotherapeutic resistance of prostate cancer to docetaxel. We treated prostate cancer cell lines with elesclomol-CuCl2 , as well as with docetaxel. We performed analyses of CCK8, colony formation tests, cell cycle flow assay, transmission electron microscopy, and mTOR signaling in treated cells, and treated a xenograft prostate cancer model with elesclomol-CuCl2 and docetaxel in vivo, and performed immunohistochemistry and Western blotting analysis in treated tumors. We found that elesclomol-CuCl2 could promote cell death and enhance chemosensitivity to docetaxel. Elesclomol-CuCl2 induced cell death and inhibited the growth of prostate cancer cells relying on copper ions-induced cuproptosis, not elesclomol. In addition, dihydrolipoamide S-acetyltransferase (DLAT) was involved in cuproptosis-enhanced drug sensitivity to docetaxel. Mechanistically, upregulated DLAT by cuproptosis inhibited autophagy, promoted G2/M phase retention of cells, and enhanced the sensitivity to docetaxel chemotherapy in vitro and in vivo via the mTOR signaling pathway. Our findings demonstrated that the cuproptosis-regulated DLAT/mTOR pathway inhibited autophagy and promoted cells in G2/M phase retention, thus enhancing the chemosensitivity to docetaxel. This discovery may provide an effective therapeutic option for treating advanced prostate cancer by inhibiting the chemotherapeutic resistance to docetaxel.

3D vascularized microphysiological system for investigation of tumor-endothelial crosstalk in anti-cancer drug resistance

Despite the advantages of microfluidic system in drug screening, vascular systems responsible for the transport of drugs and nutrients have been hardly considered in the microfluidic-based chemotherapeutic screening. Considering the physiological characteristics of highly vascularized urinary tumors, we here investigated the chemotherapeutic response of bladder tumor cells using a vascularized tumor on a chip. The microfluidic chip was designed to have open-top region for tumor sample introduction and hydrophilic rail for spontaneous hydrogel patterning, which contributed to the construction of tumor-hydrogel-endothelium interfaces in a spatiotemporal on-demand manner. Utilizing the chip where intravascularly injected cisplatin diffuse across the endothelium and transport into tumor samples, chemotherapeutic responses of cisplatin-resistant or -susceptible bladder tumor cells were evaluated, showing the preservation of cellular drug resistance even within the chip. The open-top structure also enabled the direct harvest of tumor samples and post analysis in terms of secretome and gene expressions. Comparing the cisplatin efficacy of the cisplatin-resistant tumor cells in the presence or absence of endothelium, we found that the proliferation rates of tumor cells were increased in the vasculature-incorporated chip. These have suggested that our vascularized tumor chip allows the establishment of vascular-gel-tumor interfaces in spatiotemporal manners and further enables investigations of chemotherapeutic screening.

Biodegradable and switchable near-infrared fluorescent probes for hypoxia detection

Aims: Among solid tumors, hypoxia is a common characteristic and responsible for chemotherapeutic resistance. Hypoxia-sensitive imaging probes are therefore essential for early tumor detection, growth monitoring and drug-response evaluation. Despite significant efforts, detecting hypoxic oxygen levels remains challenging. Materials & methods: This paper demonstrates the use of an amine-rich carbon dot probe functionalized with an imidazole group that exhibits reversible fluorescence switching in normoxic and hypoxic environments. Results & conclusion: We demonstrate the ability to emit near-infrared light only under hypoxic conditions. The probes are found to be biodegradable in the presence of human digestive enzymes such as lipase. Ex vivo tissue imaging experiments revealed promising near-infrared signals even at a depth of 5 mm for the probe under ex vivo imaging conditions.

Phosphorylation of USP29 by CDK1 Governs TWIST1 Stability and Oncogenic Functions

Triple-negative breast cancer (TNBC) is a highly lethal malignancy with limited therapy options. TWIST1, a key transcriptional factor of epithelial-mesenchymal transition (EMT), contributes to self-renewal of cancer stem-like cells (CSCs), chemo-resistance, metastasis, and TNBC-related death. However, the mechanism by which TWIST1 is deregulated in TNBC remains elusive. Here, USP29 is identified as a bona fide deubiquitinase of TWIST1. The deubiquitination of TWIST1 catalyzed by USP29 is required for its stabilization and subsequent EMT and CSC functions in TNBC, thereby conferring chemotherapeutic resistance and metastasis. Furthermore, the results unexpectedly reveal that CDK1 functions as the direct USP29 activator. Mechanistically, CDK1-mediated phosphorylation of USP29 is essential for its deubiquitinase activity toward TWIST1 and TWIST1 driven-malignant phenotypes in TNBC, which could be markedly mitigated by the genetic ablation or pharmacological inhibition of CDK1. Moreover, the histological analyses show that CDK1 and USP29 are highly upregulated in TNBC samples, which positively correlate with the expression of TWIST1. Taken together, the findings reveal a previously unrecognized tumor-promoting function and clinical significance of the CDK1-USP29 axis through stabilizing TWIST1 and provide the preclinical evidence that targeting this axis is an appealing therapeutic strategy to conquer chemo-resistance and metastasis in TNBC.

Silicon nanowire array overcomes chemotherapeutic resistance by inducing the differentiation of breast cancer stem cells

Currently, traditional cancer treatment strategies are greatly challenged by the existence of cancer stem cells (CSCs), which are root cause of chemotherapy resistance. Differentiation therapy presents a novel therapeutic strategy for CSC-targeted therapy. However, there are very few studies on the induction of CSCs differentiation so far. Silicon nanowire array (SiNWA) with many unique properties is considered to be an excellent material for various applications ranging from biotechnology to biomedical applications. In this study, we report the SiNWA differentiates MCF-7-derived breast CSCs (BCSCs) into non-CSCs by modulating the morphology of cells. In vitro, the differentiated BCSCs lose the stemness properties and thus become sensitive to chemotherapeutic drugs, eventually leading to the death of BCSCs. Therefore, this work suggests a potential approach for overcoming chemotherapeutic resistance.

Coding roles of long non-coding RNAs in breast cancer: Emerging molecular diagnostic biomarkers and potential therapeutic targets with special reference to chemotherapy resistance

Dysregulation of epigenetic mechanisms have been depicted in several pathological consequence such as cancer. Different modes of epigenetic regulation (DNA methylation (hypomethylation or hypermethylation of promotor), histone modifications, abnormal expression of microRNAs (miRNAs), long non-coding RNAs, and small nucleolar RNAs), are discovered. Particularly, lncRNAs are known to exert pivot roles in different types of cancer including breast cancer. LncRNAs with oncogenic and tumour suppressive potential are reported. Differentially expressed lncRNAs contribute a remarkable role in the development of primary and acquired resistance for radiotherapy, endocrine therapy, immunotherapy, and targeted therapy. A wide range of molecular subtype specific lncRNAs have been assessed in breast cancer research. A number of studies have also shown that lncRNAs may be clinically used as non-invasive diagnostic biomarkers for early detection of breast cancer. Such molecular biomarkers have also been found in cancer stem cells of breast tumours. The objectives of the present review are to summarize the important roles of oncogenic and tumour suppressive lncRNAs for the early diagnosis of breast cancer, metastatic potential, and chemotherapy resistance across the molecular subtypes.

Curcumin Nanofibers: A Novel Approach to Enhance the Anticancer Potential and Bioavailability of Curcuminoids

Development of novel treatment methods for cancer is needed given the limitations of current treatment methods, including side effects and chemotherapeutic resistance, which may provide new hope to cancer patients. Cancer is the second leading cause of global mortality. Curcumin, the active ingredient of turmeric, has been used since ancient times for various therapeutic purposes. Several studies have identified its activity against cancer. Despite the established anticancer activity of curcumin, its low aqueous solubility and bioavailability are barriers to its effectiveness. In an attempt to solve this problem, many studies have formulated curcumin nanofiber preparations using a variety of methods. Electrospinning is a simple and affordable method for the production of nanofibers. Studies have shown increased curcumin bioavailability in nanofibers resulting from their high surface/volume ratio and porosity. We have undertaken a detailed review of studies on the anticancer effects of curcumin nanofibers. Curcumin acts by inhibiting various biological cancer pathways, including NF-κB, mTOR, complex I, cytokines, expression of p-p65, Ki67, and angiogenesis-associated genes. It also induces apoptosis through activation of caspase pathways and ROS production in cancer cells. Curcumin-loaded PLA50/PVP50/Cur15 nanofibers were investigated in breast cancer, one of the most studied cancers, and was shown to have significant effects on the widely used HeLa-cell line. Most of the studies undertaken have been performed in cell lines in vitro, while relatively few animal studies have been reported. More preclinical and clinical studies are needed to evaluate the anticancer activity of curcumin nanofibers. Amongst studies undertaken, a variety of curcumin nanofibers of various formulations have been shown to suppress a variety of cancer types. Overall, curcumin nanofibers have been found to be more efficient than free curcumin. Thus, curcumin nanofibers have been observed to improvise cancer treatment, offering great potential for effective cancer management. Further studies, both in vitro and in vivo, involving curcumin nanofibers have the potential to benefit cancer management.

Glutathione peroxidase 4-dependent glutathione high-consumption drives acquired platinum chemoresistance in lung cancer-derived brain metastasis

BACKGROUND

Platinum-based chemotherapy is effective in inducing shrinkage of primary lung cancer lesions; however, it shows finite therapeutic efficacy in patients suffering from brain metastasis (BM). The intrinsic changes of BM cells, which contribute to the poor results remain unknown.

METHODS

Platinum drug-sensitivity was assessed by utilizing a preclinical BM model of PC9 lung adenocarcinoma cells in vitro and in vivo. High consumption of glutathione (GSH) and two associated upregulated proteins (GPX4 and GSTM1) in BM were identified by integrated metabolomics and proteomics in cell lines and verified by clinical serum sample. Gain-of-function and rescue experiments were implemented to reveal the impact and mechanism of GPX4 and GSTM1 on the chemosensitivity in BM. The interaction between GPX4 and GSTM1 was examined by immunoblotting and immunoprecipitation. The mechanism of upregulation of GPX4 was further uncovered by luciferase reporter assay, immunoprecipitation, and electrophoretic mobility shift assay.

RESULTS

The derivative brain metastatic subpopulations (PC9-BrMs) of parental cells PC9 developed obvious resistance to platinum. Radically altered profiles of BM metabolism and protein expression compared with primary lung cancer cells were described and GPX4 and GSTM1 were identified as being responsible for the high consumption of GSH, leading to decreased chemosensitivity by negatively regulating ferroptosis. Besides, GSTM1 was found regulated by GPX4, which was transcriptionally activated by the Wnt/NR2F2 signaling axis in BM.

CONCLUSIONS

Collectively, our findings demonstrated that Wnt/NR2F2/GPX4 promoted acquired chemoresistance by suppressing ferroptosis with high consumption of GSH. GPX4 inhibitor was found to augment the anticancer effect of platinum drugs in lung cancer BM, providing novel strategies for lung cancer patients with BM.

Effects of miR-224-5p-enhanced downregulation of pannexin-1 on docetaxel-induced apoptosis in amoeboid-like CD44high oral cancer cells

We previously found that microRNAs play major roles in the maintenance of amoeboid-like oral squamous cell carcinoma (OSCC) cells with high expression of CD44 (CD44^high ). However, the roles of microRNAs in chemotherapeutic resistance exhibited by CD44^high amoeboid-like OSCC cells are unclear. Here, docetaxel-induced apoptosis was examined in CD44^high OSCC cells (CD44^high OM-1 cells) cultured on laminin-coated silicone gel. Amoeboid-like CD44^high OSCC cells exhibited robust resistance to docetaxel-induced apoptosis and significant upregulation of miR-224-5p expression compared with epithelial-like CD44^high OSCC cells and mesenchymal-like CD44^high OSCC cells. The expression of pannexin-1 (PANX1), a channel-forming protein that regulates the release of ATP, was significantly upregulated following transfection of amoeboid-like CD44^high OSCC cells with an miR-224-5p inhibitor. These results suggest that miR-224-5p inhibits PANX1 expression. Furthermore, miR-224-5p inhibitor-transfected amoeboid-like CD44^high OSCC cells exhibited significant enhancement of the proportion of apoptotic cells; however, this effect was significantly inhibited by knockdown of PANX1 with PANX1 small interfering RNA. Additionally, the miR-224-5p inhibitor-enhanced extracellular ATP levels were significantly reduced by PANX1 knockdown. These findings imply that miR-224-5p plays a vital role in the resistance to docetaxel-induced apoptosis by attenuating PANX1-induced ATP discharge. Moreover, amoeboid-like CD44^high OSCC cells may be involved in chemotherapeutic resistance of OSCC.

Glutathione S-Transferase M3 Is Associated with Glycolysis in Intrinsic Temozolomide-Resistant Glioblastoma Multiforme Cells

Glioblastoma multiforme (GBM) is a malignant primary brain tumor. The 5-year relative survival rate of patients with GBM remains <30% on average despite aggressive treatments, and secondary therapy fails in 90% of patients. In chemotherapeutic failure, detoxification proteins are crucial to the activity of chemotherapy drugs. Usually, glutathione S-transferase (GST) superfamily members act as detoxification enzymes by activating xenobiotic metabolites through conjugation with glutathione in healthy cells. However, some overexpressed GSTs not only increase GST activity but also trigger chemotherapy resistance and tumorigenesis-related signaling transductions. Whether GSTM3 is involved in GBM chemoresistance remains unclear. In the current study, we found that T98G, a GBM cell line with pre-existing temozolomide (TMZ) resistance, has high glycolysis and GSTM3 expression. GSTM3 knockdown in T98G decreased glycolysis ability through lactate dehydrogenase A activity reduction. Moreover, it increased TMZ toxicity and decreased invasion ability. Furthermore, we provide next-generation sequencing-based identification of significantly changed messenger RNAs of T98G cells with GSTM3 knockdown for further research. GSTM3 was downregulated in intrinsic TMZ-resistant T98G with a change in the expression levels of some essential glycolysis-related genes. Thus, GSTM3 was associated with glycolysis in chemotherapeutic resistance in T98G cells. Our findings provide new insight into the GSTM3 mechanism in recurring GBM.

Mechanisms of Ferroptosis and Application to Head and Neck Squamous Cell Carcinoma Treatments

Many kinds of cancer cells are intrinsically sensitive to ferroptosis, and research interest regarding ferroptosis has been sparked by its significant role in many detrimental diseases. Ferroptosis is a novel type of iron-dependent cell death mediated by accumulation of reactive oxygen species and lipid peroxidation. Furthermore, a large number of small agents can induce ferroptosis in numerous kinds of cancer cells, including prostate cancer, pancreatic cancer, breast cancer, lymphomas, and renal cancer. These insights may help discover novel approaches for cancer therapeutic strategies; however, there is considerable uncertainty regarding ferroptosis in head and neck cancer (HNC). So far, no review of the current studies on this topic has been published. Therefore, we here elaborate the mechanisms of ferroptosis and summarize the latest findings regarding its role in HNC according to current literature. The respective findings shed light on the role of ferroptosis in HNC treatment with a number of important implications for future practice in HNC management, as outlined in this review.

ATDC binds to KEAP1 to drive NRF2-mediated tumorigenesis and chemoresistance in pancreatic cancer

Pancreatic ductal adenocarcinoma is a lethal disease characterized by late diagnosis, propensity for early metastasis and resistance to chemotherapy. Little is known about the mechanisms that drive innate therapeutic resistance in pancreatic cancer. The ataxia-telangiectasia group D-associated gene (ATDC) is overexpressed in pancreatic cancer and promotes tumor growth and metastasis. Our study reveals that increased ATDC levels protect cancer cells from reactive oxygen species (ROS) via stabilization of nuclear factor erythroid 2-related factor 2 (NRF2). Mechanistically, ATDC binds to Kelch-like ECH-associated protein 1 (KEAP1), the principal regulator of NRF2 degradation, and thereby prevents degradation of NRF2 resulting in activation of a NRF2-dependent transcriptional program, reduced intracellular ROS and enhanced chemoresistance. Our findings define a novel role of ATDC in regulating redox balance and chemotherapeutic resistance by modulating NRF2 activity.

Endostar Rebuilding Vascular Homeostasis and Enhancing Chemotherapy Efficacy in Cervical Cancer Treatment

Background

The incidence rate of cervical cancer is the highest in the reproductive tract and is not sensitive to chemotherapy. An appropriate amount of anti-angiogenic agents can reconstruct tumor blood vessels in a short period of time and form vascular homeostasis, increase the function of blood vessel perfusion and reverse the multidrug resistance of chemotherapy, which is also called “vascular normalization.” Endostar (a recombinant human endostatin) was developed by China and as a multi-target anti-angiogenesis agent. Many reports about endostar involved the treatment of non-small cell lung cancer, fewer reports are on cervical cancer.

Purpose

To determine whether endostar can rebuild tumor vascular homeostasis and enhance chemotherapy effects for patients with cervical cancer.

Methods

In this study, the patients with cervical cancer within stage IIB2 were selected, endostar combined with cisplatin+paclitaxel neoadjuvant chemotherapy (NACT) before radical surgical operation was adopted, patients outcome and adverse reaction were followed up. The changes of tumor vascular structure and perfusion function before and after endostar given were evaluated by histopathology and dynamic contrast-enhanced magnetic resonance imaging (DEC-MRI). VEGF-Notch signal pathway was detected for the regulating mechanism of vascular proliferation in different groups. GraphPad Prism 6 software was used for statistical analysis of the study results.

Results

Endostar enhanced the short-term (2 year) overall survival (OS), progression-free survival (PFS) rates for cervical cancer patients. All the same, endostar increased long-term (5 year) OS for cervical cancer patients. Endostar therapy exhibited with mild adverse reaction. MRI showed endostar+NACT further reduce tumor volume than NACT alone. The parameters of Ktrans, Ve for DEC-MRI in endostar group exhibited obviously increase than NACT group. Tumor vascular maturation index α-SMA/CD31 in endostar group increased obviously than NACT group, correspondingly Ki67 staining for tumor proliferative rates, lymphovascular space invasion in endostar group further declined than NACT group. The genes and proteins expression of VEGFR2, Notch1, Notch4, Dll4, Jag1 were obviously downregulated in endostar group comparing to NACT group.

Conclusion

Endostar restored vascular homeostasis in cervical cancer temporarily, enhanced chemotherapeutic agents effects in cervical cancer, increased patient OS ratio. Endostar+NACT treatment may provide a new target therapy for cervical cancer.

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Aberrant Partial Chromosomal Instability With Chemotherapeutically Resistant Metachronous Colorectal Cancer Following a Synchronous Primary Colorectal Cancer: A Case Report

The diagnosis of synchronous colorectal cancer (CRC) is crucial as the management, including the extent of surgical resection, depends on it. There have been numerous studies on the clinicopathological features of synchronous CRC; however, only a few studies have discussed synchronous cancer treatment. The guidelines to best manage the synchronous and metachronous CRC are limited, especially the most appropriate surgical treatment and chemotherapy based on mutational analysis of mismatch repair genes and the carcinoma sequence model. We present a rare case of a metachronous CRC with intact nuclear expression of microsatellite instability markers following a synchronous CRC, and it failed to show any significant response to surgical resection and chemoradiotherapy.

A 53-year-old female presented in June 2016 with bleeding per rectum for one month, weight loss, and a recent history of altered bowel habits. The per rectal examination revealed a circumferential growth. Colonoscopy and biopsy yielded multiple polyps throughout the colon and invasive adenocarcinoma in the upper and lower one-third of the rectum. The above features were highly suggestive of synchronous CRC. Serologic studies revealed elevated carcinoembryonic antigen (CEA). Excisional biopsy of mesenteric and retroperitoneal lymph nodes during proctocolectomy and end ileostomy was negative for metastasis, including the other metastatic workup preoperatively-eight months post-resection and adjuvant chemotherapy patient developed metachronous CRC. Mutational analysis showed positivity only for adenomatous polyposis coli (APC) while negative for KRAS, NRAS, and BRAF. Immunohistochemistry (IHC) markers for mismatch repair (MMR) proteins showed intact protein expression. The patient was given multiple chemotherapy cycles throughout her course, including oral capecitabine, XELOX (capecitabine + oxaliplatin), cetuximab-capecitabine, cetuximab-irinotecan, and FOLFIRI (5‐fluorouracil [5‐FU] + irinotecan + folinic acid)-bevacizumab, as is the standard chemotherapy regimen for these tumors.

The diagnosis of metachronous CRC with intensive follow up is crucial. IHC markers for MMR proteins showed intact protein expression ruling out the possibility of microsatellite instability and Lynch Syndrome. The only presence of APC mutation indicates a partial chromosomal instability. During the course, the patient had either stable size of the masses or developed new metastatic growth despite intensive chemotherapeutic regimes. Unfortunately, there are no precise guidelines based on aberrant mutational analysis regarding synchronous and metachronous CRCs management.

Inhibition of pyruvate dehydrogenase kinase‑1 by dicoumarol enhances the sensitivity of hepatocellular carcinoma cells to oxaliplatin via metabolic reprogramming

The Warburg effect is a unique metabolic feature of the majority of tumor cells and is closely related to chemotherapeutic resistance. Pyruvate dehydrogenase kinase 1 (PDK1) is considered a 'switch' that controls the fate of pyruvate in glucose metabolism. However, to date, to the best of our knowledge, there are only a few studies to available which had studied the reduction of chemotherapeutic resistance via the metabolic reprogramming of tumor cells with PDK1 as a target. In the present study, it was found dicoumarol (DIC) reduced the phosphorylation of pyruvate dehydrogenase (PDH) by inhibiting the activity of PDK1, which converted the metabolism of human hepatocellular carcinoma (HCC) cells to oxidative phosphorylation, leading to an increase in mitochondrial reactive oxygen species ROS (mtROS) and a decrease in mitochondrial membrane potential (MMP), thereby increasing the apoptosis induced by oxaliplatin (OXA). Furthermore, the present study elucidated that the targeting of PDK1 may be a potential strategy for targeting metabolism in the chemotherapy of HCC. In addition, DIC as an 'old drug' exhibits novel efficacy, bringing new hope for antitumor therapy.

Luminescent PtII and PtIV Platinacycles with Anticancer Activity Against Multiplatinum-Resistant Metastatic CRC and CRPC Cell Models

Platinum-based chemotherapy persists to be the only effective therapeutic option against a wide variety of tumours. Nevertheless, the acquisition of platinum resistance is utterly common, ultimately cornering conventional platinum drugs to only palliative in many patients. Thus, encountering alternatives that are both effective and non-cross-resistant is urgent. In this work, we report the synthesis, reduction studies, and luminescent properties of a series of cyclometallated (C,N,N')Pt^IV compounds derived from amine-imine ligands, and their remarkable efficacy at the high nanomolar range and complete lack of cross-resistance, as an intrinsic property of the platinacycle, against multiplatinum-resistant colorectal cancer (CRC) and castration-resistant prostate cancer (CRPC) metastatic cell lines generated for this work. We have also determined that the compounds are effective and selective for a broader cancer panel, including breast and lung cancer. Additionally, selected compounds have been further evaluated, finding a shift in their antiproliferative mechanism towards more cytotoxic and less cytostatic than cisplatin against cancer cells, being also able to oxidize cysteine residues and inhibit topoisomerase II, thereby holding great promise as future improved alternatives to conventional platinum drugs.

Berberine Maintains the Neutrophil N1 Phenotype to Reverse Cancer Cell Resistance to Doxorubicin

This study explores the contributions of neutrophils to chemotherapeutic resistance and berberine-regulated cancer cell sensitivity to doxorubicin (DOX). In vitro experiments, continuous DOX treatment led to the shift of HL-60 cells to N2 neutrophils and thus induced chemotherapeutic resistance. The combination treatment with DOX and 2 µM berberine resulted in the differentiation of HL-60 cells toward N1 and therefore stimulated HL-60 cell immune clearance. Berberine increased reactive oxygen species (ROS) and decreased autophagy and therefore induced apoptosis in HL-60-N2 cells with morphological changes, but had no effect on cell viability in HL-60-N1 cells. The neutrophil-regulating efficacy of berberine was confirmed in the urethane-induced lung carcinogenic model and H22 liver cancer allograft model. Furthermore, we found that DOX-derived neutrophils had high levels of CD133 and CD309 surface expression, which prevented both chemotherapeutic sensitivity and immune rejection by self-expression of PD-L1 and surface expression of PD-1 receptor on T cells, whereas berberine could downregulate CD133 and CD309 surface expression. Finally, berberine-relevant targets and pathways were evaluated. This study first suggests an important role of berberine in regulating neutrophil phenotypes to maintain cancer cell sensitivity to DOX.

PRDM14: A Potential Target for Cancer Therapy

PRDM14 belongs to the PR domain-containing (PRDM) family. Although a precise understanding focused on the function of PRDM14 to maintain stemness and pluripotency in embryonic stem cells via epigenetic mechanisms, growing experimental evidence has been linked PRDM14 to human cancers. In adults, PRDM14 has low expression in human tissues. Aberrant PRDM14 expression is connected with various malignant histological types and solid cancers, where PRDM14 can act as a driver of oncogenic processes. Overexpression of RPDM14 enhanced cancer cells growth and reduced cancer cells sensitive to chemotherapeutic agents. Reducing the expression of PRDM14 in cancer cells can enhance the therapeutic sensitivity of drugs to cancer cells, suggesting that aberrant PRDM14 may have a carcinogenic characteristic in tumor therapy and as a new molecular target. This review summarizes the structure and oncogenic properties of PRDM14 in different malignancies and suggests that PRDM14 may be a potential therapeutic molecular target for tumor treatment.

Multifaceted Impact of MicroRNA 493-5p on Genome-Stabilizing Pathways Induces Platinum and PARP Inhibitor Resistance in BRCA2-Mutated Carcinomas

BRCA1/2-mutated ovarian cancers (OCs) are defective in homologous recombination repair (HRR) of double-strand breaks (DSBs) and thereby sensitive to platinum and PARP inhibitors (PARPis). Multiple PARPis have recently received US Food and Drug Administration (FDA) approval for treatment of OCs, and resistance to PARPis is a major clinical problem. Utilizing primary and recurrent BRCA1/2-mutated carcinomas from OC patients, patient-derived lines, and an in vivo BRCA2-mutated mouse model, we identified a microRNA, miR-493-5p, that induced platinum/PARPi resistance exclusively in BRCA2-mutated carcinomas. However, in contrast to the most prevalent resistance mechanisms in BRCA mutant carcinomas, miR-493-5p did not restore HRR. Expression of miR-493-5p in BRCA2-mutated/depleted cells reduced levels of nucleases and other factors involved in maintaining genomic stability. This resulted in relatively stable replication forks, diminished single-strand annealing of DSBs, and increased R-loop formation. We conclude that impact of miR-493-5p on multiple pathways pertinent to genome stability cumulatively causes PARPi/platinum resistance in BRCA2 mutant carcinomas.

Transcriptional Activation of Gstp1 by MEK/ERK Signaling Confers Chemo-Resistance to Cisplatin in Lung Cancer Stem Cells

Lung cancer management remains a challenge due to its asymptomatic and late presentation when it is metastatic. The clinical response to the first-line platinum-based chemotherapy in patients with advanced lung cancer is disappointing due to the development of chemoresistance. Chemoresistance is a complex phenomenon. Mechanistic research using experimental models has yielded limited clinical results to help increase understanding for overcoming resistance. While the role of lung CSCs in conferring multidrug resistance has been postulated, experimental evidence remains associative and lacks in depth mechanistic inquisition. In the present study, using mouse and human lung adenocarcinoma cell lines and their respective paired CSC derivative cell lines that we generated, we identified cancer stem cell component of lung adenocarcinoma as the source that confers multidrug resistance phenotype. Mechanistically, Gstp1 confers cisplatin resistance in mouse and human lung CSC models, both in vitro and in vivo. Further, transcriptional activation of Gstp1 expression by MEK/ERK signaling underlies cisplatin resistance in lung CSC cells. Moreover, we show that GSTP1 expression is a poor diagnostic and prognostic marker for human lung adenocarcinoma, thus is of high clinical relevance. Taken together, we have provided mechanistic understanding of the lung CSC in mediating chemoresistance.

A bibliometric analysis of long non-coding RNA and chemotherapeutic resistance research

The global outputs of annual publication in long non-coding RNAs (lncRNAs) and chemotherapeutic resistance research exponentially increased from 2 in 2008 to 176 in 2017. Using Java application CiteSpace V and VOSviewer, this study assessed the publication model of lncRNAs and chemoresistance by bibliometric analysis. Totally, 2883 authors contributed 528 publications of lncRNAs and chemoresistance in 215 academic journals in the recent decade (2008-2018). Oncotarget in the 215 academic journals published the highest number of publications (60). China had the highest number of publication outputs (358). The leading institute was Nanjing Medical University. Wang Y was the most influential author (13 counts). Gupta RA had the most cited documents (87 counts). “Gene expression” and “poor prognosis” were identified as the hotspots. “Cancer stem cell”, “HOTAIR” and “UCA1” were the frontiers of the fields in recent years. The increase of publications on lncRNAs and chemotherapeutic resistance will continue in the next years. HOTAIR and UCA1 with multiple roles in drug resistance may offer big opportunities for targeted chemoresistance in cancer therapy. These results may help us discover and explain the possible underlying laws of the subject.

CCN2 promotes drug resistance in osteosarcoma by enhancing ABCG2 expression

In recent years, osteosarcoma survival rates have failed to improve significantly with conventional treatment modalities because of the development of chemotherapeutic resistance. The human breast cancer resistance protein/ATP binding cassette subfamily G member 2 (BCRP/ABCG2), a member of the ATP-binding cassette family, uses ATP hydrolysis to expel xenobiotics and chemotherapeutics from cells. CCN family member 2 (CCN2) is a secreted protein that modulates the biological function of cancer cells, enhanced ABCG2 protein expression and activation in this study via the α6β1 integrin receptor and increased osteosarcoma cell viability. CCN2 treatment downregulated miR-519d expression, which promoted ABCG2 expression. In a mouse xenograft model, knockdown of CCN2 expression increased the therapeutic effect of doxorubicin, which was reversed by ABCG2 overexpression. Our data show that CCN2 increases ABCG2 expression and promotes drug resistance through the α6β1 integrin receptor, whereas CCN2 downregulates miR-519d. CCN2 inhibition may represent a new therapeutic concept in osteosarcoma.

Serum miR-4530 sensitizes breast cancer to neoadjuvant chemotherapy by suppressing RUNX2

Purpose

Neoadjuvant chemotherapy (NAC) plays a pivotal role in the treatment of locally advanced breast cancer (LABC); however, breast cancer is a heterogeneous disease, individual responses to chemotherapy are highly variable. Therefore, the purpose of the current research is to identify biomarkers that can predict the chemotherapeutic response.

Patients and methods

We recruited 78 patients with primary breast cancer who underwent taxane- and anthracycline-based NAC; these patients were divided into sensitive and resistant groups according to the Response Evaluation Criteria in Solid Tumors (RECIST) criteria. The microRNA microarray was conducted to explore differentially expressed miRNAs. Quantitative real-time polymerase chain reaction (qRT-PCR) further validated the relationship between miR-4530 and chemosensitivity in breast cancer patients.

Results

No significant differences were observed between the two groups regarding the clinicopathological characteristics. miR-4530 showed the most potential involving breast cancer chemosensitivity. Mechanically, RUNX2 was identified one of the direct targets of miR-4530 and responsible for breast cancer chemosensitivity.

Conclusion

Our results revealed that elevated serum miR-4530 levels may sensitize breast cancer to taxane- and anthracycline-based NAC by suppressing RUNX2; therefore, this miRNA has the potential to be a new biomarker for predicting breast cancer chemosensitivity.

Maintenance of cancer stemness by miR-196b-5p contributes to chemoresistance of colorectal cancer cells via activating STAT3 signaling pathway. Oncotarget. 2017;8:49807-49823. [PMID: 28591704 PMCID: PMC5564809 DOI: 10.18632/oncotarget.17971]

Emerging studies indicated that cancer stem cells represent a subpopulation of cells within the tumor that is responsible for chemotherapeutic resistance. However, the underlying mechanism is still not clarified yet. Here we report that miR-196b-5p is dramatically upregulated in CRC tissues and high expression of miR-196b-5p correlates with poor survival in CRC patients. Moreover, recurrent gains (amplification) contribute to the miR-196b-5p overexpression in CRC tissues. Silencing miR-196b-5p suppresses spheroids formation ability, the fraction of SP cells, expression of stem cell factors and the mitochondrial potential, and enhances the apoptosis induced by 5-fluorouracil in CRC cells; while ectopic expression of miR-196b-5p yields an opposite effect. In addition, downregulation of miR-196b-5p resensitizes CRC cells to 5-fluorouracil in vivo. Our results further demonstrate that miR-196b-5p promotes stemness and chemoresistance of CRC cells to 5-fluorouracil via targeting negative regulators SOCS1 and SOCS3 of STAT3 signaling pathway, giving rise to activation of STAT3 signaling. Interestingly, miR-196b-5p is highly enriched in the serum exosomes of patients with CRC compared to the healthy control subjects. Thus, our results unravel a novel mechanism of miR-196b-5p implicating in the maintenance of stem cell property and chemotherapeutic resistance in CRC, offering a potential rational registry of anti-miR-196b-5p combining with conventional chemotherapy against CRC.

Upregulation of let-7f-5p promotes chemotherapeutic resistance in colorectal cancer by directly repressing several pro-apoptotic proteins

Colorectal cancer (CRC) is one of the most frequently occurring primary malignant tumors worldwide. Chemotherapeutic resistance is a major clinical problem in the treatment of CRC. Therefore, it is of great importance to investigate novel biomarkers that may predict chemoresistance and facilitate the development of individualized treatment for patients with CRC. The present study reported that let-7f-5p expression was elevated in chemotherapy-resistant CRC tissues compared with chemotherapy-sensitive tissues. Furthermore, upregulating let-7f-5p increased the expression levels of the anti-apoptotic proteins, B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra large (Bcl-xL), and decreased the activity of caspase-3 and caspase-9 in CRC cells. By contrast, downregulating let-7f-5p yielded the opposite effect. Notably, the results indicated that let-7f-5p promoted chemotherapeutic resistance by directly repressing the expression of several pro-apoptotic proteins, including tumor protein p53, tumor protein p53-inducible nuclear protein 1, tumor protein p53-inducible nuclear protein 2 and caspase-3. Therefore, a novel mechanism by which let-7f-5p enhances the resistance of CRC cells to chemotherapeutics has been revealed, indicating that silencing let-7f-5p may become an effective therapeutic strategy against CRC.

Uncoupling protein 2 downregulation by hypoxia through repression of peroxisome proliferator-activated receptor γ promotes chemoresistance of non-small cell lung cancer

Hypoxic microenvironment is critically involved in the response of non-small cell lung cancer (NSCLC) to chemotherapy, the mechanisms of which remain largely unknown. Here, we found that NSCLC patients exhibited increased chemotherapeutic resistance when complicated by chronic obstructive pulmonary disease (COPD), a critical cause of chronic hypoxemia. The downregulation of uncoupling protein 2 (UCP2), which is attributed to hypoxia-inducible factor 1 (HIF-1)-mediated suppression of the transcriptional factor peroxisome proliferator-activated receptor γ (PPARγ), was involved in NSCLC chemoresistance, and predicted a poor survival rate of patients receiving routine chemotherapy. UCP2 suppression induced reactive oxygen species production and upregulation of the ABC transporter protein ABCG2, which leads to chemoresistance by promoting drug efflux. UCP2 downregulation also altered metabolic rates as shown by elevated glucose uptake and reduced oxygen consumption. These data suggest that UCP2 is a key mediator of hypoxia-triggered chemoresistance of NSCLCs, which can be potentially targeted in clinical treatment of chemo-refractory NSCLCs.

The synergistic role of ATP-dependent drug efflux pump and focal adhesion signaling pathways in vinorelbine resistance in lung cancer

The vinorelbine (VRB) plus cisplatin regimen is widely used to treat non-small cell lung cancer (NSCLC), but its cure rate is poor. Drug resistance is the primary driver of chemotherapeutic failure, and the causes of resistance remain unclear. By focusing on the focal adhesion (FA) pathway, we have highlighted a signaling pathway that promotes VRB resistance in lung cancer cells. First, we established VRB-resistant (VR) lung cancer cells (NCI-H1299 and A549) and examined its transcriptional changes, protein expressions, and activations. We treated VR cells by Src Family Kinase (SFK) inhibitors or gene silencing and examined cell viabilities. ATP-binding Cassette Sub-family B Member 1 (ABCB1) was highly expressed in VR cells. A pathway analysis and western blot analysis revealed the high expression of integrins β1 and β3 and the activation of FA pathway components, including Src family kinase (SFK) and AKT, in VR cells. SFK involvement in VRB resistance was confirmed by the recovery of VRB sensitivity in FYN knockdown A549 VR cells. Saracatinib, a dual inhibitor of SFK and ABCB1, had a synergistic effect with VRB in VR cells. In conclusion, ABCB1 is the primary cause of VRB resistance. Additionally, the FA pathway, particularly integrin, and SFK, are promising targets for VRB-resistant lung cancer. Further studies are needed to identify clinically applicable target drugs and biomarkers that will improve disease prognoses and predict therapeutic efficacies.

miR-1266 Contributes to Pancreatic Cancer Progression and Chemoresistance by the STAT3 and NF-κB Signaling Pathways

Pancreatic cancer is characterized by chemoresistance after several cycles of chemotherapy, which is a major issue responsible for treatment failure of pancreatic cancer. Therefore, it is necessary to explore the specific mechanism underlying chemotherapeutic resistance to overcome this issue. Here we report that miR-1266 is dramatically elevated and correlates with poor survival and chemotherapy response in pancreatic cancer patients. Upregulation of miR-1266 enhanced the chemoresistance of pancreatic cancer cells to gemcitabine (GEM) in vitro and in vivo; conversely, inhibition of miR-1266 yielded the opposite effect. Importantly, silencing of miR-1266 restored the sensitivity of pancreatic cancer cells to GEM in a dose-dependent manner in vivo. Furthermore, our results demonstrate that miR-1266 promotes resistance of pancreatic cancer cells to GEM by targeting multiple negative regulators of the STAT3 and NF-κB pathways, including SOCS3, PTPN11, ITCH, and TNIP1, leading to constitutive activation of STAT3 and NF-κB signaling. Thus, our findings clarify a novel mechanism by which miR-1266 induces chemotherapeutic resistance in pancreatic cancer, indicating that miR-1266 may be used as chemotherapeutic response indicator. Antagomir-1266 as a chemotherapeutic sensitizer, in combination with GEM, may serve as a rational regimen in the treatment of chemotherapy-resistant pancreatic cancer.

Over-activated PD-1/PD-L1 axis facilitates the chemoresistance of diffuse large B-cell lymphoma cells to the CHOP regimen

Interaction between the programmed cell death ligand 1 (PD-L1) and programmed cell death 1 (PD-1) contributes to tumor cell resistance to chemotherapeutic agents. PD-L1 is expressed in the cells of diffuse large B-cell lymphoma (DLBCL), one common type of malignant non-Hodgkin lymphomas. However, little is known about how the PD-1/PD-L1 pathway functions in the pathogenesis of DLBCL. Therefore, the present study investigated whether and how the PD-1/PD-L1 axis is involved in regulating the sensitivity of CRL2631, a DLBCL cell line, to the CHOP (Cyclophosphamide, Hydroxydaunorubicin/adriamycin, Oncovin/vincristine and Prednisone) chemotherapeutic regimen. CHOP treatment significantly decreased cell survival rate and increased apoptosis in CRL2631 cells. The application of recombinant human PD-1 (rPD-1) significantly decreased the cytotoxic effects of the CHOP regimen in CRL2631 cells, but not in the CRL2631 cells with PD-L1 deficiency. In the CRL2631 cells, rPD-1 enhanced the activity of the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt1) pathway. However, the activity level of the PI3K/Akt1 pathway was decreased in CHOP-treated CRL2631 cells. The selective PI3K inhibitor BKM120 significantly increased CHOP-induced apoptosis, but this effect was abolished by rPD-1 and aggravated by PD-L1 knockdown. In CHOP-treated PD-L1 knockdown cells, the increased apoptosis was markedly inhibited by the overexpression of constitutively active Akt1. Overall, the results demonstrate that the over-activated PD-1/PD-L1 axis is associated with chemotherapeutic resistance of DLBCL cells to the CHOP regimen, potentially through a PI3K-dependent mechanism.

Function of insulin-like growth factor 1 receptor in cancer resistance to chemotherapy

Drug resistance is a primary cause of chemotherapeutic failure; however, how this resistance develops is complex. A comprehensive understanding of chemotherapeutic resistance mechanisms may aid in identifying more effective drugs and improve the survival rates of patients with cancer. Insulin-like growth factor 1 receptor (IGF1R), a member of the insulin receptor family, has been extensively assessed for biological activity, and its putative contribution to tumor cell development and progression. Furthermore, researchers have attended to drugs that target IGF1R since IGF1R functions as a membrane receptor. However, how IGF1R participates in chemotherapeutic resistance remains unclear. Therefore, the present study described the IGF1R gene and its associated signaling pathways, and offered details of IGF1R-induced tumor chemoresistance associated with promoting cell proliferation, inhibition of apoptosis, regulation of ATP-binding cassette transporter proteins and interactions with the extracellular matrix. The present study offered additional explanations for tumor chemotherapy resistance and provided a theoretical basis of IGF1R and its downstream pathways for future possible chemotherapy treatment options.

Posttranscriptional Regulation of PARG mRNA by HuR Facilitates DNA Repair and Resistance to PARP Inhibitors

The majority of pancreatic ductal adenocarcinomas (PDAC) rely on the mRNA stability factor HuR (ELAV-L1) to drive cancer growth and progression. Here, we show that CRISPR-Cas9-mediated silencing of the HuR locus increases the relative sensitivity of PDAC cells to PARP inhibitors (PARPi). PDAC cells treated with PARPi stimulated translocation of HuR from the nucleus to the cytoplasm, specifically promoting stabilization of a new target, poly (ADP-ribose) glycohydrolase (PARG) mRNA, by binding a unique sequence embedded in its 3' untranslated region. HuR-dependent upregulation of PARG expression facilitated DNA repair via hydrolysis of polyADP-ribose on related repair proteins. Accordingly, strategies to inhibit HuR directly promoted DNA damage accumulation, inefficient PAR removal, and persistent PARP-1 residency on chromatin (PARP-1 trapping). Immunoprecipitation assays demonstrated that the PARP-1 protein binds and posttranslationally modifies HuR in PARPi-treated PDAC cells. In a mouse xenograft model of human PDAC, PARPi monotherapy combined with targeted silencing of HuR significantly reduced tumor growth compared with PARPi therapy alone. Our results highlight the HuR-PARG axis as an opportunity to enhance PARPi-based therapies. Cancer Res; 77(18); 5011-25. ©2017 AACR.

MicroRNA-205-5p regulates the chemotherapeutic resistance of hepatocellular carcinoma cells by targeting PTEN/JNK/ANXA3 pathway

Hepatocellular carcinoma (HCC) is a common malignant tumor of the digestive system, and patients with advanced HCC have a poor outlook, partly due to resistance to chemotherapeutic drugs. Previous studies have implicated microRNAs in the regulation of chemoresistance, and we have previously shown that microRNA (miR)-205-5p is down-regulated in multiple hepatoma cell lines. Here, we investigate whether miR-205-5p is involved in chemotherapeutic resistance in HCC. Expression of miR-205-5p was measured by real-time quantitative reverse transcription PCR and cell viability was determined using a CCK-8 cell viability assay. Expression of proteins in the PTEN/JNK/ANXA3 pathway were assessed via Western blotting. We found that miR-205-5p expression was down-regulated in all HCC cell lines investigated. In addition, miR-205-5p expression was upregulated by 5-fluorouracil (5-Fu) treatment in Bel-7402 (Bel) cells. Interestingly, miR-205-5p expression was increased in multidrug-resistant Bel-7402/5-Fu (Bel/Fu) cells, compared with Bel cells. We next demonstrated that sensitivity to 5-Fu was increased in Bel/Fu cells after treatment with a miR-205-5p inhibitor. Similarly, increased resistance to 5-Fu was observed in Bel cells after transfection with a miR-205-5p mimic. We injected nude mice with Bel/5-Fu cells to promote tumor growth, and found that co-treatment with a miR-205-5p antagomir and 5-Fu slowed tumor growth more than either treatment alone. Finally, we found that these effects were all associated with changes in the PTEN/JNK/ANXA3 pathway. In conclusion, inhibition of miR-205-5p may reverse chemotherapeutic resistance to 5-Fu, and this may occur via the PTEN/JNK/ANXA3 pathway.

BDNF: An Oncogene or Tumor Suppressor?

Neurotrophins are a family of growth factors that are vital to the proper development of the central nervous system. Their effects on cells are governed by the expression and activation of the tyrosine kinase receptors TrkA, TrkB and TrkC. TrkB has been immensely implicated in mediating neuronal migration, development and differentiation. It has also been shown to protect several neuronal cell types from an array of cytotoxic stressors after activation by its conjugate ligand brain-derived neurotrophic factor (BDNF). Over the past two decades, it has been shown that TrkB and BDNF are up-regulated in many types of cancers, conferring aggressive phenotypes underpinned by their resistance to several standard chemotherapeutic agents. This resistance to chemotherapy is modulated by the downstream targets of the TrkB receptor which include the well-characterized PI3K /Akt growth pathway, a hallmark of uncontrolled cancer cell growth and proliferation. Pre-clinical efforts to develop inhibitors of this receptor are promising, and such inhibitors also seem to sensitize cancer cells to standard chemotherapies. However, new evidence suggests that BDNF overexpression in the hypothalamus has immunoaugmenting properties, eliciting an increased anti-tumor immune response and reducing the activity of several proteins that would normally confer resistance to chemotherapeutic agents. In the current work, we provide a global analysis of the physiological consequences of TrkB receptor activation in vitro and discuss the dynamic consequences of TrkB activation in vivo. Finally, we propose a clinically-feasible option for increasing BDNF expression in the hypothalamus to more readily utilize the oncolytic effects of BDNF.

Breast cancer resistance protein (BCRP)-containing circulating microvesicles contribute to chemoresistance in breast cancer

At present, one of the major problems of cancer therapy is drug resistance. Breast cancer resistance protein (BCRP), a marker of the multidrug-resistant phenotype, affects drug absorption, distribution, metabolism, and excretion in normal tissues. Meanwhile, extracellular vesicles (EVs) have attracted increasing attention as a medium of cell-to-cell communication. However, the association between BCRP and circulating EVs remains unclear. The present study demonstrated that patients who did not respond or had progressive/stable disease following chemotherapy had markedly higher BCRP levels compared to those that did not receive chemotherapy. Moreover, BCRP was upregulated at the mRNA and protein levels in tumor-derived circulating EVs from patients with a poor response to chemotherapy. Interestingly, the results also demonstrated that BCRP was co-expressed with MUC1, which is frequently expressed in breast cancer and is exported via EVs, and both BCRP and MUC1 were up-regulated after chemotherapy. In conclusion, the present study indicates that tumor-derived circulating EVs that carry BCRP may serve as a predictive biomarker of the response to chemotherapy for breast cancer. In addition, the results provide a window for individualized treatment to overcome resistance to chemotherapeutic drugs.

Functions and therapeutic roles of exosomes in cancer

The role of exosomes in cancer development has become the focus of much research, due to the many emerging roles possessed by exosomes. These micro-vesicles that are ubiquitously released in to the extracellular milieu, have been found to regulate immune system function, particularly in tumorigenesis, as well as conditioning future metastatic sites for the attachment and growth of tumor tissue. Through an interaction with a range of host tissue, exosomes are able to generate a pro-tumor environment that is essential for carcinogenesis. Herein, we discuss the contents of exosomes and their contribution to tumorigenesis, as well as their role in chemotherapeutic resistance and the development of novel cancer treatments and the identification of cancer biomarkers.

Treatment of capecitabine-induced hand-foot syndrome using a topical retinoid: A case report

Capecitabine is a chemotherapeutic drug used in patients with breast, colon and gastric cancer. Hand-foot syndrome (HFS) is a type of dermatitis that frequently occurs as a reaction to capecitabine. To date, no effective strategies have been found to prevent or reverse HFS. Furthermore, chemotherapy induces an elevation in the expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF), and this activation represents a critical mechanism for the induction of chemotherapeutic resistance. Adapalene is a third-generation synthetic retinoid. Topical retinoids are important therapeutic anti-aging agents for managing photodamaged skin, and are known to increase HB-EGF levels, which is important for skin wound healing. Accordingly, the current report focused on the topical retinoids that increase HB-EGF expression in the skin, and we hypothesized that these topical retinoids induce local chemotherapeutic resistance in the skin of patients receiving chemotherapy and consequently, decrease the cutaneous side-effects of chemotherapy. This report presents a case of the successful treatment of refractory HFS induced by capecitabine using the topical application of adapalene. Topical adapalene was applied for 3 months and significantly reduced inflammation and pain following chemotherapy. Topical retinoids may have the potential to effectively treat capecitabine-induced HFS by increasing HB-EGF expression and decreasing cutaneous side-effects. Further studies are required to establish the therapeutic efficacy of topical retinoids on HFS.

BITC Sensitizes Pancreatic Adenocarcinomas to TRAIL-induced Apoptosis

Pancreatic adenocarcinoma is an aggressive cancer with a greater than 95% mortality rate and short survival after diagnosis. Chemotherapeutic resistance hinders successful treatment. This resistance is often associated with mutations in codon 12 of the K-Ras gene (K-Ras 12), which is present in over 90% of all pancreatic adenocarcinomas. Codon 12 mutations maintain Ras in a constitutively active state leading to continuous cellular proliferation. Our study determined if TRAIL resistance in pancreatic adenocarcinomas with K-Ras 12 mutations could be overcome by first sensitizing the cells with Benzyl isothiocyanate (BITC). BITC is a component of cruciferous vegetables and a cell cycle inhibitor. BxPC3, MiaPaCa2 and Panc-1 human pancreatic adenocarcinoma cell lines were examined for TRAIL resistance. Our studies show BITC induced TRAIL sensitization by dual activation of both the extrinsic and intrinsic apoptotic pathways.