Long non-coding RNA GHET1 contributes to chemotherapeutic resistance to Gemcitabine in bladder cancer

Relationship between lncRNA MALAT1 and Chemo-radiotherapy Resistance of Cancer Cells: Uncovered Truths

The advancement of novel technologies, coupled with bioinformatics, has led to the discovery of additional genes, such as long noncoding RNAs (lncRNAs), that are associated with drug resistance. LncRNAs are composed of over 200 nucleotides and do not possess any protein coding function. These lncRNAs exhibit lower conservation across species, are typically expressed at low levels, and often display high specificity towards specific tissues and developmental stages. The LncRNA MALAT1 plays crucial regulatory roles in various aspects of genome function, encompassing gene transcription, splicing, and epigenetics. Additionally, it is involved in biological processes related to the cell cycle, cell differentiation, development, and pluripotency. Recently, MALAT1 has emerged as a novel mechanism contributing to drug resistance or sensitivity, attracting significant attention in the field of cancer research. This review aims to explore the mechanisms through which MALAT1 confers resistance to chemotherapy and radiotherapy in cancer cells.

Long non-coding RNA (lncRNA) PVT1 in drug resistance of cancers: Focus on pathological mechanisms

According to estimates, cancer will be the leading cause of death globally in 2022, accounting for 9.6 million deaths. At present, the three main therapeutic modalities utilized to treat cancer are radiation therapy, chemotherapy, and surgery. However, during treatment, tumor cells resistant to chemotherapy may arise. Drug resistance remains a major oppose since it often leads to therapeutic failure. Furthermore, the term "acquired drug resistance" describes the situation where tumor cells already display drug resistance before undergoing chemotherapy. However, little is still known about the basic mechanisms underlying chemotherapy-induced drug resistance. The development of new technologies and bioinformatics has led to the discovery of additional genes associated with drug resistance. Long noncoding RNA plasmacytoma variant translocation 1 (PVT1) has been linked to an increased risk of cancer, according to a growing body of research. Apart from biological functions associated with cell division, development, pluripotency, and cell cycle, lncRNA PVT1 contributes significantly to the regulation of various aspects of genome function, such as transcription, splicing, and epigenetics. The article will address the mechanism by which lncRNA PVT1 influences drug resistance in cancer cells.

Emerging roles of ncRNAs regulating ABCC1 on chemotherapy resistance of cancer - a review

In the process of chemotherapy, drug resistance of cancer cells is a common and difficult problem of chemotherapy failure, and it is also the main cause of cancer recurrence and metastasis. Non-coding RNAs (ncRNAs) refer to the RNA that does not encode proteins, including microRNA (miRNA), long non-coding RNA (lncRNA) and circularRNA (circRNA), etc. NcRNAs are involved in a series of important life processes and further regulate the expression of ABCC1 by directly or indirectly up-regulating or down-regulating the expression of targeted mRNAs, making cancer cells more susceptible to drug resistance. A growing number of studies have shown that ncRNAs have effects on cancer cell proliferation, invasion, metastasis, and drug sensitivity, by regulating the expression of ABCC1. In this review, we will discuss the emerging roles of ncRNAs regulating ABCC1 in chemotherapy resistance and mechanisms to reverse drug resistance as well as provide potential targets for future cancer treatment.

Molecular landscape of LncRNAs in bladder cancer: From drug resistance to novel LncRNA-based therapeutic strategies

Bladder cancer (BC) is a common and serious type of cancer that ranks among the top ten most prevalent malignancies worldwide. Due to the high occurrence rate of BC, the aggressive nature of cancer cells, and their resistance to medication, managing this disease has become a growing challenge in clinical care. Long noncoding RNAs (lncRNAs) are a group of RNA transcripts that do not code for proteins and are more than 200 nucleotides in length. They play a significant role in controlling cellular pathways and molecular interactions during the onset, development and progression of different types of cancers. Recent advancements in high-throughput gene sequencing technology have led to the identification of various differentially expressed lncRNAs in BC, which indicate abnormal expression. In this review, we summarize that these lncRNAs have been found to impact several functions related to the development of BC, including proliferation, cell growth, migration, metastasis, apoptosis, epithelial-mesenchymal transition, and chemo- and radio-resistance. Additionally, lncRNAs may improve prognosis prediction for BC patients, indicating a future use for them as prognostic and diagnostic biomarkers for BC patients. This review highlights that genetic tools and anti-tumor agents, such as CRISPR/Cas systems, siRNA, shRNA, antisense oligonucleotides, and vectors, have been created for use in preclinical cancer models. This has led to a growing interest in using lncRNAs based on positive research findings.

Role of the long non-coding RNAs in regulation of Gemcitabine response in tumor cells

Chemotherapy is widely used as one of the first line therapeutic methods in cancer patients. However, chemotherapeutic resistance is one of the most common problems in cancer patients, which leads to the therapeutic failure and tumor relapse. Considering the side effects of chemotherapy drugs in normal tissues, it is required to investigate the molecular mechanisms involved in drug resistance to improve the therapeutic strategies in cancer patients. Long non-coding RNAs (lncRNAs) have pivotal roles in regulation of cellular processes associated with drug resistance. LncRNAs deregulations have been frequently reported in a wide range of chemo-resistant tumors. Gemcitabine (GEM) as a nucleoside analog has a wide therapeutic application in different cancers. However, GEM resistance is considered as a therapeutic challenge. Considering the role of lncRNAs in the occurrence of GEM resistance, in the present review we discussed the molecular mechanisms of lncRNAs in regulation of GEM response among cancer patients. It has been reported that lncRNAs have mainly an oncogenic role as the inducers of GEM resistance through direct or indirect regulation of transcription factors, autophagy, polycomb complex, and signaling pathways such as PI3K/AKT, MAPK, WNT, JAK/STAT, and TGF-β. This review paves the way to present the lncRNAs as non-invasive markers to predict GEM response in cancer patients. Therefore, lncRNAs can be introduced as the efficient markers to reduce the possible chemotherapeutic side effects in GEM resistant cancer patients and define a suitable therapeutic strategy among these patients.

Epigenetic and Immunological Features of Bladder Cancer

Bladder cancer (BLCA) is one of the most common types of malignant tumors of the urogenital system in adults. Globally, the incidence of BLCA is more than 500,000 new cases worldwide annually, and every year, the number of registered cases of BLCA increases noticeably. Currently, the diagnosis of BLCA is based on cystoscopy and cytological examination of urine and additional laboratory and instrumental studies. However, cystoscopy is an invasive study, and voided urine cytology has a low level of sensitivity, so there is a clear need to develop more reliable markers and test systems for detecting the disease with high sensitivity and specificity. Human body fluids (urine, serum, and plasma) are known to contain significant amounts of tumorigenic nucleic acids, circulating immune cells and proinflammatory mediators that can serve as noninvasive biomarkers, particularly useful for early cancer detection, follow-up of patients, and personalization of their treatment. The review describes the most significant advances in epigenetics of BLCA.

A review on the role of GHET1 in different cancers

Gastric cancer High Expressed Transcript 1 (GHET1) is an RNA gene located on chromosome 7q36.1. This non-coding RNA is involved in the pathology of different cancers. It can regulate cell proliferation, apoptosis and cell cycle transition. Moreover, it induces epithelial-mesenchymal transition. Up-regulation of GHET1 has been correlated with poor prognosis of patients with different malignancies. Besides, its up-regulation has been mostly detected in later stages and advanced grades of cancers. This review summarizes recent studies on the expression of GHET1, its in vitro functions, and its impact on the beginning and progression of cancer based on xenograft models of cancer.

Inhibition of PP2A by LB100 sensitizes bladder cancer cells to chemotherapy by inducing p21 degradation

PURPOSE

Bladder carcinoma (BLCA) is the most common urinary tract malignancy and exhibits a poor response to chemotherapy. Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase involved in a wide variety of regulatory cellular processes, including apoptosis and the DNA-damage response (DDR). LB100, a small molecule inhibitor of PP2A, has been shown to act as a chemo-sensitizer in multiple types of cancer. However, the anti-tumor effect and mode of action of LB100 in BLCA have yet to be identified.

METHODS

In vitro and in vivo experiments were performed to assess the anti-tumor effect of LB100 alone or in combination with gemcitabine. Mass spectrometry (MS)-based phosphoproteomics analysis was used to identify the downstream substrates of PP2A and to explore the mechanism underlying LB100-induced DNA damage and apoptosis. In addition, we established a chemo-resistant BLCA cell line (RT-112-R) by prolonged drug exposure and determined the effect of LB100 in enhancing genotoxicity in BLCA cell lines and xenograft mouse models.

RESULTS

We found that LB100 is sufficient to induce an anti-tumor response in BLCA cells by inducing DNA damage and apoptosis both in vitro and in vivo. Furthermore, we found that PP2A potentially dephosphorylates p-p21-ser130 to stabilize p21. Inhibition of PP2A by LB100 increased the level of p-p21-ser130, subsequently leading to a reduction in p21 level in a dose-dependent manner. In addition, we found that treatment of LB100 abrogated the G1/S cell cycle checkpoint, resulting in increased phosphorylation of γH2AX in BLCA cells. Moreover, LB100 enhanced genotoxicity in chemo-resistant BLCA cells by inducing DNA damage and apoptosis in vitro and in vivo.

CONCLUSION

Our findings indicate that PP2A may serve as a potential therapeutic target in BLCA through regulating p21 stability.

Ursolic Acid Enhances Cytotoxicity of Doxorubicin-Resistant Triple-Negative Breast Cancer Cells via ZEB1-AS1/miR-186-5p/ABCC1 Axis

Background: Triple-negative breast cancer (TNBC) is the most serious subtype of breast cancer (BC) and has been a great health threat to females. Although chemotherapeutic agent contributes a lot to TNBC treatment, drug resistance has been a great obstacle for chemotherapies. Ursolic acid (UA), a pentacyclic triterpenoid compound, was reported to reverse paclitaxel resistance in BC. However, whether UA could affect the resistance of TNBC cells to other drugs such as doxorubicin (DOX) remains to be discovered. Materials and Methods: MTT assay, EdU assay, colony formation assay, and flow cytometry analysis were implemented to detect the viability, proliferation, and apoptosis of DOX-resistant MDA-MB-468 and MDA-MB-436 cells with or without UA treatment. Mechanism assays including RIP, RNA pull-down, and luciferase reporter assays verified the interaction between RNAs. Results: UA treatment hindered the growth and mitigated the DOX resistance of DOX-resistant MDA-MB-468 and MDA-MB-436 cells. Mechanistically, multidrug resistance-associated protein 1 (ABCC1) expression was downregulated by UA treatment. MiR-186-5p was verified to target ABCC1. Further, UA-inhibited ZEB1-AS1 (zinc finger E-box binding homeobox 1 antisense RNA 1) was verified as a competitive endogenous RNA (ceRNA) to upregulate ABCC1 through sponging miR-186-5p. Importantly, UA treatment impaired the malignant phenotypes of DOX-resistant MDA-MB-468 and MDA-MB-436 cells through ZEB1-AS1/ABCC1 axis. Conclusion: UA promotes TNBC cell sensitivity to DOX through inactivating ZEB1-AS1/miR-186-5p/ABCC1 signaling.

Targeted Inhibition of O-Linked β-N-Acetylglucosamine Transferase as a Promising Therapeutic Strategy to Restore Chemosensitivity and Attenuate Aggressive Tumor Traits in Chemoresistant Urothelial Carcinoma of the Bladder

Acquisition of acquired chemoresistance during treatment cycles in urothelial carcinoma of the bladder (UCB) is the major cause of death through enhancing the risk of cancer progression and metastasis. Elevated glucose flux through the abnormal upregulation of O-linked β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) controls key signaling and metabolic pathways regulating diverse cancer cell phenotypes. This study showed that OGT expression levels in two human UCB cell models with acquired resistance to gemcitabine and paclitaxel were significantly upregulated compared with those in parental cells. Reducing hyper-O-GlcNAcylation by OGT knockdown (KD) markedly facilitated chemosensitivity to the corresponding chemotherapeutics in both cells, and combination treatment with OGT-KD showed more severe growth defects in chemoresistant sublines. We subsequently verified the suppressive effects of OGT-KD monotherapy on cell migration/invasion in vitro and xenograft tumor growth in vivo in chemoresistant UCB cells. Transcriptome analysis of these cells revealed 97 upregulated genes, which were enriched in multiple oncogenic pathways. Our final choice of suspected OGT glycosylation substrate was VCAN, S1PR3, PDGFRB, and PRKCG, the knockdown of which induced cell growth defects. These findings demonstrate the vital role of dysregulated OGT activity and hyper-O-GlcNAcylation in modulating treatment failure and tumor aggression in chemoresistant UCB.

Biological functions and clinical significance of long noncoding RNAs in bladder cancer

Bladder cancer (BCa) is one of the 10 most common cancers with high morbidity and mortality worldwide. Long noncoding RNAs (lncRNAs), a large class of noncoding RNA transcripts, consist of more than 200 nucleotides and play a significant role in the regulation of molecular interactions and cellular pathways during the occurrence and development of various cancers. In recent years, with the rapid advancement of high-throughput gene sequencing technology, several differentially expressed lncRNAs have been discovered in BCa, and their functions have been proven to have an impact on BCa development, such as cell growth and proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and drug-resistance. Furthermore, evidence suggests that lncRNAs are significantly associated with BCa patients' clinicopathological characteristics, especially tumor grade, TNM stage, and clinical progression stage. In addition, lncRNAs have the potential to more accurately predict BCa patient prognosis, suggesting their potential as diagnostic and prognostic biomarkers for BCa patients in the future. In this review, we briefly summarize and discuss recent research progress on BCa-associated lncRNAs, while focusing on their biological functions and mechanisms, clinical significance, and targeted therapy in BCa oncogenesis and malignant progression.

Long non-coding RNAs as new players in bladder cancer: Lessons from pre-clinical and clinical studies

The clinical management of bladder cancer (BC) has become an increasing challenge due to high incidence rate of BC, malignant behavior of cancer cells and drug resistance. The non-coding RNAs are considered as key factors involved in BC progression. The long non-coding RNAs (lncRNAs) are RNA molecules and do not encode proteins. They have more than 200 nucleotides in length and affect gene expression at epigenetic, transcriptional and post-transcriptional phases. The lncRNAs demonstrate abnormal expression in BC cells and tissues. The present aims to identifying lncRNAs with tumor-suppressor and tumor-promoting roles, and evaluating their roles as regulatory of growth and migration. Apoptosis, glycolysis and EMT are tightly regulated by lncRNAs in BC. Response of BC cells to cisplatin, doxorubicin and gemcitabine chemotherapy is modulated by lncRNAs. LncRNAs regulate immune cell infiltration in tumor microenvironment and affect response of BC cells to immunotherapy. Besides, lncRNAs are able to regulate microRNAs, STAT3, Wnt, PTEN and PI3K/Akt pathways in affecting both proliferation and migration of BC cells. Noteworthy, anti-tumor compounds and genetic tools such as siRNA, shRNA and CRISPR/Cas systems can regulate lncRNA expression in BC. Finally, lncRNAs and exosomal lncRNAs can be considered as potential diagnostic and prognostic tools in BC.

Long non-coding RNA GHET1 promotes thyroid cancer cell proliferation and invasion

BACKGROUND

We aimed to evaluate the role of long non-coding RNA (LncRNA) gastric carcinoma proliferation-enhancing transcript 1 (GHET1) on thyroid cancer (TC) behavior in vitro.

METHODS

TC tissues and paired adjacent normal tissues were obtained after surgical excision from 43 patients with TC. The expression of LncRNA GHET1 was analyzed by real-time (RT) PCR. Human papillary thyroid cancer cell lines (TPC-1, BCPAP) were used to examine the role of LncRNA GHET1 in vitro. Cell proliferation was determined by CCK8 and cell colony formation assays. Transwell and wound-healing assays were used to detect the invasion and migration of thyroid cancer cells.

RESULTS

Our results showed that LncRNA GHET1 was significantly more upregulated in TC tissues than in adjacent normal tissues. LncRNA GHET1 was also increased in thyroid cancer cell lines compared to normal thyroid cell lines. The upregulation of LncRNA GHET1 was significantly associated with tumor invasion, gender, and lymph node metastasis in patients with thyroid cancer. The in vitro studies showed that silencing LncRNA GHET1 in BCPAP cells inhibited cell proliferation, cell invasion, and migration. Silencing of LncRNA GHETI also promoted the cell apoptotic rate, caused an increase in the cell population at the G0/G1 phase, and decreased the cell population at the S phase. In contrast, the overexpression of LncRNA GHET1 promoted cell proliferation, invasion, and migration, inhibited cell apoptosis, and increased cell population at the S phase in TPC cells.

CONCLUSIONS

LncRNA GHET1 dysregulation might be involved in the carcinogenesis of thyroid cancer. LncRNA GHET1 could be used as a potential molecular marker and molecular target for TC.

Crosstalk of long non-coding RNAs and EMT: Searching the missing pieces of an incomplete puzzle for lung cancer therapy

BACKGROUND

Lung cancer is considered to be the first place among the cancer-related deaths worldwide and demands novel strategies in the treatment of this life-threatening disorder. The aim of this review is to explore regulation of epithelial-to-mesenchymal transition (EMT) by long non-coding RNAs (lncRNAs) in lung cancer.

INTRODUCTION

LncRNAs can be considered as potential factors for targeting in cancer therapy, since they regulate a bunch of biological processes, e.g. cell proliferation, differentiation and apoptosis. The abnormal expression of lncRNAs occurs in different cancer cells. On the other hand, epithelial-to-mesenchymal transition (EMT) is a critical mechanism participating in migration and metastasis of cancer cells.

METHOD

Different databases including Googlescholar, Pubmed and Sciencedirect were used for collecting articles using keywords such as "LncRNA", "EMT", and "Lung cancer".

RESULT

There are tumor-suppressing lncRNAs that can suppress EMT and metastasis of lung cancer cells. Expression of such lncRNAs undergoes down-regulation in lung cancer progression and restoring their expression is of importance in suppressing lung cancer migration. There are tumor-promoting lncRNAs triggering EMT in lung cancer and enhancing their migration.

CONCLUSION

LncRNAs are potential regulators of EMT in lung cancer, and targeting them, both pharmacologically and genetically, can be of importance in controlling migration of lung cancer cells.

The role of long non-coding RNAs in mediating chemoresistance by modulating autophagy in cancer

Cancer is a complex process in which protein-coding and non-coding genes play essential roles. Long noncoding RNAs (lncRNAs), as a subclass of noncoding genes, are implicated in various cancer processes including growth, proliferation, metastasis, and angiogenesis. Due to presence in body fluids such as blood and urine, lncRNAs have become novel biomarkers in cancer detection, diagnosis, progression, and therapy response. Remarkably, increasing evidence has verified that lncRNAs play essential roles in chemoresistance by targeting different signalling pathways. Autophagy, a highly conserved process in response to environmental stresses such as starvation and hypoxia, plays a paradoxical role in inducing resistance or sensitivity to chemotherapy agents. In this regard, we reviewed chemoresistance, the role of lncRNAs in cancer, and the role of lncRNAs in chemoresistance by modulating autophagy.

Non coding RNAs as the critical factors in chemo resistance of bladder tumor cells

BACKGROUND

Bladder cancer (BCa) is the ninth frequent and 13th leading cause of cancer related deaths in the world which is mainly observed among men. There is a declining mortality rates in developed countries. Although, the majority of BCa patients present Non-Muscle-Invasive Bladder Cancer (NMIBC) tumors, only 30% of patients suffer from muscle invasion and distant metastases. Radical cystoprostatectomy, radiation, and chemotherapy have proven to be efficient in metastatic tumors. However, tumor relapse is observed in a noticeable ratio of patients following the chemotherapeutic treatment. Non-coding RNAs (ncRNAs) are important factors during tumor progression and chemo resistance which can be used as diagnostic and prognostic biomarkers of BCa.

MAIN BODY

In present review we summarized all of the lncRNAs and miRNAs associated with chemotherapeutic resistance in bladder tumor cells.

CONCLUSIONS

This review paves the way of introducing a prognostic panel of ncRNAs for the BCa patients which can be useful to select a proper drug based on the lncRNA profiles of patients to reduce the cytotoxic effects of chemotherapy in such patients.

Clinicopathological and Prognostic Value of Gastric Carcinoma Highly Expressed Transcript 1 in Cancer: A Meta-Analysis

Background

Long noncoding RNA gastric cancer highly expressed transcript 1 (lncRNA GHET1) is often reported to be abnormally expressed in multiple cancers, but the situation is different in different cancers. Therefore, a meta-analysis is necessary to clarify the value of lncRNA GHET1 as a prognostic indicator in cancer.

Methods

Relevant research studies on lncRNA GHET1 and cancer were retrieved from three electronic literature databases of Web of Science, PubMed, and OVID. Meanwhile, hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to explore the relationship between lncRNA GHET1 expression and survival of cancer patients. The odds ratios (ORs) and 95% CIs were calculated to assess the association of lncRNA GHET1 expression with pathological parameters of cancer patients.

Results

The meta-analysis included a total of 11 studies involving 714 cancer patients. The pooled HR suggests that high lncRNA GHET1 expression is associated with poor overall survival. In addition, high expression of lncRNA GHET1 was found to be associated with larger tumor size, poor histological grade, high tumor stage, lymph node metastasis, and distant metastasis.

Conclusions

High lncRNA GHET1 expression can predict poor survival and pathological parameters. And lncRNA GHET1 could serve as a new indicator in multiple cancers.

lncRNA and Mechanisms of Drug Resistance in Cancers of the Genitourinary System

Available systemic treatment options for cancers of the genitourinary system have experienced great progress in the last decade. However, a large proportion of patients eventually develop resistance to treatment, resulting in disease progression and shorter overall survival. Biomarkers indicating the increasing resistance to cancer therapies are yet to enter clinical routine. Long non-coding RNAs (lncRNA) are non-protein coding RNA transcripts longer than 200 nucleotides that exert multiple types of regulatory functions of all known cellular processes. Increasing evidence supports the role of lncRNAs in cancer development and progression. Additionally, their involvement in the development of drug resistance across various cancer entities, including genitourinary malignancies, are starting to be discovered. Consequently, lncRNAs have been suggested as factors in novel therapeutic strategies to overcome drug resistance in cancer. In this review, the existing evidences on lncRNAs and their involvement in mechanisms of drug resistance in cancers of the genitourinary system, including renal cell carcinoma, bladder cancer, prostate cancer, and testicular cancer, will be highlighted and discussed to facilitate and encourage further research in this field. We summarize a significant number of lncRNAs with proposed pathways in drug resistance and available reported studies.

Silence of FAM83H-AS1 promotes chemosensitivity of gastric cancer through Wnt/β-catenin signaling pathway

Gastric cancer (GC) is a malignant tumor originated from the epithelium of gastric mucosa, its incidence is second only to lung cancer in China. Chemotherapy is one of the most effective methods to treat GC, but some patients are insensitive to chemotherapeutic drugs, leading to chemotherapy failure. In this study, the expression of FAM83H-AS1 was up-regulated in GC tissues and cell lines, and was related to differentiation, invasion depth and chemotherapy insensitivity of GC patients. FAM83H-AS1 was high-expressed in chemoresistant GC tissues and cell line (SGC7901/R), and silence of FAM83H-AS1 sensitized SGC7901/R cells to cisplatin (CDDP) and 5-fluorouracil (5-FU). In addition, silence of FAM83H-AS1 could inactivate Wnt/β-catenin signaling pathway in SGC7901/R cells. The activating of Wnt/β-catenin signaling pathway reversed the promoting effect of FAM83H-AS1 silence on chemotherapy sensitivity, which meant Wnt/β-catenin signaling pathway mediated the regulation of FAM83H-AS1 on chemotherapy sensitivity in SGC7901/R cells. In conclusion, FAM83H-AS1 is related with the CDDP and 5-FU insensitivity of GC patients, silence of FAM83H-AS1 promotes chemosensitivity of GC through Wnt/β-catenin signaling pathway.

CircPVT1 contributes to chemotherapy resistance of lung adenocarcinoma through miR-145-5p/ABCC1 axis

Recently, increasing studies have confirmed some circRNAs were involved in the genesis of chemotherapy resistance in almost all kinds of malignant tumors, including lung adenocarcinoma (LAD). Nevertheless, the function and mechanism of circPVT1 in regulating chemotherapy resistance of LAD has not been elucidated so far. The current study found circPVT1 was highly expressed in LAD, which expression was positively related to N stage and chemotherapy insensitivity (cisplatin and pemetrexed) of LAD patients, and it was an independent prognostic biomarker for LAD patients. The circPVT1 expression was up-regulated in LAD tissues and cell line (A549/DR) resistant to cisplatin and pemetrexed. CircPVT1 knockdown sensitized A549/DR cells to cisplatin and pemetrexed. RNA pull-down assay et al. confirmed circPVT1 acted as a ceRNA for miR-145-5p in A549/DR cells. In addition, miR-145-5p was lowly expressed in cisplatin and pemetrexed resistant LAD tissues and cell line, and its over-expression also sensitized A549/DR cells to cisplatin and pemetrexed. The luciferase reporter assay et al. proved ABCC1 was a target gene of miR-145-5p in A549/DR cells. Moreover, miR-145-5p enhancement partly restored the effecting of circPVT1 knockdown on chemotherapy resistance in A549/DR cells, miR-145-5p/ABCC1 pathway mediated chemotherapy resistance induced by circPVT1 knockdown in LAD cells. In conclusion, the high-expression of circPVT1 is related with the cisplatin and pemetrexed insensitivity of LAD patients, circPVT1 contributes to cisplatin and pemetrexed chemotherapy resistance through miR-145-5p/ABCC1 axis.

Circular RNA CircHIPK3 Promotes Gemcitabine Sensitivity in Bladder Cancer

Purpose: Recent studies showed circular RNA (circRNA) played important regulatory roles in tumors, including genesis of chemotherapy resistance. In this study, the role of circHIPK3 on chemotherapy resistance of bladder cancer (BC) will be clarified. Methods: Real-time quantitative PCR was applied to examine the circHIPK3 expression. The gemcitabine sensitivity and cell proliferation viability were analyzed by Cell Counting Kit-8 assay. Double-stained flow cytometry was used to detect the cell apoptosis. Results: In BC tissues and cell lines, the circHIPK3 expression was down-regulated. Its expression had a negative correlation with pathological grade, lymph node metastasis and gemcitabine insensitivity of BC patients. CircHIPK3 was a independent prognostic biomarker for BC patients. The expression of circHIPK3 in T24/gem and J82/gem cell lines (resistant to gemcitabine) was down-regulated significantly. The over-expression of circHIPK3 decreased IC50 of gemcitabine and promoted gemcitabine's cytotoxicity in T24/gem and J82/gem cells. Conclusions: The circHIPK3 is low-expressed in BC and is an independent prognostic biomarker for BC patients. The low-expression of circHIPK3 is associated with the insensitivity to gemcitabine of BC patients, over-expression of circHIPK3 promotes gemcitabine sensitivity in BC.