NOTCH1 signaling promotes chemoresistance via regulating ABCC1 expression in prostate cancer stem cells

Key genes and molecular mechanisms related to Paclitaxel Resistance

Paclitaxel is commonly used to treat breast, ovarian, lung, esophageal, gastric, pancreatic cancer, and neck cancer cells. Cancer recurrence is observed in patients treated with paclitaxel due to paclitaxel resistance emergence. Resistant mechanisms are observed in cancer cells treated with paclitaxel, docetaxel, and cabazitaxel including changes in the target molecule β-tubulin of mitosis, molecular mechanisms that activate efflux drug out of the cells, and alterations in regulatory proteins of apoptosis. This review discusses new molecular mechanisms of taxane resistance, such as overexpression of genes like the multidrug resistance genes and EDIL3, ABCB1, MRP1, and TRAG-3/CSAG2 genes. Moreover, significant lncRNAs are detected in paclitaxel resistance, such as lncRNA H19 and cross-resistance between taxanes. This review contributed to discovering new treatment strategies for taxane resistance and increasing the responsiveness of cancer cells toward chemotherapeutic drugs.

Molecular panorama of therapy resistance in prostate cancer: a pre-clinical and bioinformatics analysis for clinical translation

Prostate cancer (PCa) is a malignant disorder of prostate gland being asymptomatic in early stages and high metastatic potential in advanced stages. The chemotherapy and surgical resection have provided favourable prognosis of PCa patients, but advanced and aggressive forms of PCa including CRPC and AVPC lack response to therapy properly, and therefore, prognosis of patients is deteriorated. At the advanced stages, PCa cells do not respond to chemotherapy and radiotherapy in a satisfactory level, and therefore, therapy resistance is emerged. Molecular profile analysis of PCa cells reveals the apoptosis suppression, pro-survival autophagy induction, and EMT induction as factors in escalating malignant of cancer cells and development of therapy resistance. The dysregulation in molecular profile of PCa including upregulation of STAT3 and PI3K/Akt, downregulation of STAT3, and aberrant expression of non-coding RNAs are determining factor for response of cancer cells to chemotherapy. Because of prevalence of drug resistance in PCa, combination therapy including co-utilization of anti-cancer drugs and nanotherapeutic approaches has been suggested in PCa therapy. As a result of increase in DNA damage repair, PCa cells induce radioresistance and RelB overexpression prevents irradiation-mediated cell death. Similar to chemotherapy, nanomaterials are promising for promoting radiosensitivity through delivery of cargo, improving accumulation in PCa cells, and targeting survival-related pathways. In respect to emergence of immunotherapy as a new tool in PCa suppression, tumour cells are able to increase PD-L1 expression and inactivate NK cells in mediating immune evasion. The bioinformatics analysis for evaluation of drug resistance-related genes has been performed.

Molecular heterogeneity in prostate cancer and the role of targeted therapy

Data collected from large-scale studies has shown that the incidence of prostate cancer globally is on the rise, which could be attributed to an overall increase in lifespan. So, the question is how has modern science with all its new technologies and clinical breakthroughs mitigated or managed this disease? The answer is not a simple one as prostate cancer exhibits various subtypes, each with its unique characteristics or signatures which creates challenges in treatment. To understand the complexity of prostate cancer these signatures must be deciphered. Molecular studies of prostate cancer samples have identified certain genetic and epigenetic alterations, which are instrumental in tumorigenesis. Some of these candidates include the androgen receptor (AR), various oncogenes, tumor suppressor genes, and the tumor microenvironment, which serve as major drivers that lead to cancer progression. These aberrant genes and their products can give an insight into prostate cancer development and progression by acting as potent markers to guide future therapeutic approaches. Thus, understanding the complexity of prostate cancer is crucial for targeting specific markers and tailoring treatments accordingly.

The Relationship between Trop-2, Chemotherapeutic Drugs, and Chemoresistance

Trop-2 is a highly conserved one-pass transmembrane mammalian glycoprotein that is normally expressed in tissues such as the lung, intestines, and kidney during embryonic development. It is overexpressed in many epithelial cancers but is absent in non-epithelial tumors. Trop-2 is an intracellular calcium signal transducer that participates in the promotion of cell proliferation, migration, invasion, metastasis, and probably stemness. It also has some tumor suppressor effects. The pro-tumoral actions have been thoroughly investigated and reported. However, Trop-2's activity in chemoresistance is less well known. We review a possible relationship between Trop-2, chemotherapy, and chemoresistance. We conclude that there is a clear role for Trop-2 in some specific chemoresistance events. On the other hand, there is no clear evidence for its participation in multidrug resistance through direct drug transport. The development of antibody conjugate drugs (ACD) centered on anti-Trop-2 monoclonal antibodies opened the gates for the treatment of some tumors resistant to classic chemotherapies. Advanced urothelial tumors and breast cancer were among the first malignancies for which these ACDs have been employed. However, there is a wide group of other tumors that may benefit from anti-Trop-2 therapy as soon as clinical trials are completed.

Molecular Insight into Prostate Cancer: Preventive Role of Selective Bioactive Molecules

Prostate cancer (CaP) is one of the most prevalent male malignancies, accounting for a considerable number of annual mortalities. However, the prompt identification of early-stage CaP often faces delays due to diverse factors, including socioeconomic inequalities. The androgen receptor (AR), in conjunction with various other signaling pathways, exerts a central influence on the genesis, progression, and metastasis of CaP, with androgen deprivation therapy (ADT) serving as the primary therapeutic strategy. Therapeutic modalities encompassing surgery, chemotherapy, hormonal intervention, and radiotherapy have been formulated for addressing early and metastatic CaP. Nonetheless, the heterogeneous tumor microenvironment frequently triggers the activation of signaling pathways, culminating in the emergence of chemoresistance, an aspect to which cancer stem cells (CSCs) notably contribute. Phytochemicals emerge as reservoirs of bioactive agents conferring manifold advantages against human morbidity. Several of these phytochemicals demonstrate potential chemoprotective and chemosensitizing properties against CaP, with selectivity exhibited towards malignant cells while sparing their normal counterparts. In this context, the present review aims to elucidate the intricate molecular underpinnings associated with metastatic CaP development and the acquisition of chemoresistance. Moreover, the contributions of phytochemicals to ameliorating CaP initiation, progression, and chemoresistance are also discussed.

Polysaccharides from Lentinus edodes prevent acquired drug resistance to docetaxel in prostate cancer cells by decreasing the TGF-β1 secretion of cancer-associated fibroblasts

Prostate cancer is one of the most prevalent lethal diseases among men globally. In the treatment of prostate cancer, the limited therapeutic efficacy of the standard non-hormonal systemic therapy docetaxel (DTX) represents an important challenge. Cancer-associated fibroblasts (CAFs) play a crucial role in resistance to therapy because of their prevalence and functional pleiotropy in tumor environments. Our previous research revealed that MPSSS, a novel polysaccharide extracted from Lentinus edodes, could significantly attenuate the immunosuppressive function of myeloid suppressor cells and CAFs. In this study, we investigated whether MPSSS could potentiate the efficacy of DTX against prostate cancer by inhibiting CAF-induced chemoresistance and elucidated its underlying mechanisms. The sensitivity of PC-3 prostate cancer cells cultured with conditioned medium derived from CAFs (CAF-CM) to DTX was assessed. The resistance effect induced by CAF-CM was abolished when CAFs were pretreated with MPSSS. Bioinformatic analysis of datasets from the Gene Expression Omnibus database revealed the activation of the transforming growth factor β1 (TGF-β1) signaling pathway in DTX-resistant cells. Based on this finding, we demonstrated that treatment with the TGF-β1 receptor inhibitor SB525334 reversed DTX resistance in CAFs, suggesting that TGF-β1 secreted by CAFs was a crucial intermediary in the development of DTX resistance in PC3 cells. Further research revealed that MPSSS decreases the secretion of TGF-β1 by inhibiting the JAK2/STAT3 pathway via Toll-like receptor 4 in CAFs. Overall, MPSSS might be a potential adjuvant treatment for DTX resistance in prostate cancer.

New insight in urological cancer therapy: From epithelial-mesenchymal transition (EMT) to application of nano-biomaterials

A high number of cancer-related deaths (up to 90) are due to metastasis and simple definition of metastasis is new colony formation of tumor cells in a secondary site. In tumor cells, epithelial-mesenchymal transition (EMT) stimulates metastasis and invasion, and it is a common characteristic of malignant tumors. Prostate cancer, bladder cancer and renal cancer are three main types of urological tumors that their malignant and aggressive behaviors are due to abnormal proliferation and metastasis. EMT has been well-documented as a mechanism for promoting invasion of tumor cells and in the current review, a special attention is directed towards understanding role of EMT in malignancy, metastasis and therapy response of urological cancers. The invasion and metastatic characteristics of urological tumors enhance due to EMT induction and this is essential for ensuring survival and ability in developing new colonies in neighboring and distant tissues and organs. When EMT induction occurs, malignant behavior of tumor cells enhances and their tend in developing therapy resistance especially chemoresistance promotes that is one of the underlying reasons for therapy failure and patient death. The lncRNAs, microRNAs, eIF5A2, Notch-4 and hypoxia are among common modulators of EMT mechanism in urological tumors. Moreover, anti-tumor compounds such as metformin can be utilized in suppressing malignancy of urological tumors. Besides, genes and epigenetic factors modulating EMT mechanism can be therapeutically targeted for interfering malignancy of urological tumors. Nanomaterials are new emerging agents in urological cancer therapy that they can improve potential of current therapeutics by their targeted delivery to tumor site. The important hallmarks of urological cancers including growth, invasion and angiogenesis can be suppressed by cargo-loaded nanomaterials. Moreover, nanomaterials can improve chemotherapy potential in urological cancer elimination and by providing phototherapy, they mediate synergistic tumor suppression. The clinical application depends on development of biocompatible nanomaterials.

State-of-the-art therapeutic strategies for targeting cancer stem cells in prostate cancer

The development of new therapeutic strategies is on the increase for prostate cancer stem cells, owing to current standardized therapies for prostate cancer, including chemotherapy, androgen deprivation therapy (ADT), radiotherapy, and surgery, often failing because of tumor relapse ability. Ultimately, tumor relapse develops into advanced castration-resistant prostate cancer (CRPC), which becomes an irreversible and systemic disease. Hence, early identification of the intracellular components and molecular networks that promote prostate cancer is crucial for disease management and therapeutic intervention. One of the potential therapeutic methods for aggressive prostate cancer is to target prostate cancer stem cells (PCSCs), which appear to be a primary focal point of cancer metastasis and recurrence and are resistant to standardized therapies. PCSCs have also been documented to play a major role in regulating tumorigenesis, sphere formation, and the metastasis ability of prostate cancer with their stemness features. Therefore, the current review highlights the origin and identification of PCSCs and their role in anti-androgen resistance, as well as stemness-related signaling pathways. In addition, the review focuses on the current advanced therapeutic strategies for targeting PCSCs that are helping to prevent prostate cancer initiation and progression, such as microRNAs (miRNAs), nanotechnology, chemotherapy, immunotherapy, the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene-editing system, and photothermal ablation (PTA) therapy.

Prostate Cancer Stem Cells: Clinical Aspects and Targeted Therapies

Despite decades of research and successful improvements in diagnosis and therapy, prostate cancer (PC) remains a major challenge. In recent years, it has become clear that PC stem cells (PCSCs) are the driving force in tumorigenesis, relapse, metastasis, and therapeutic resistance of PC. In this minireview, we discuss the impact of PCSCs in the clinical practice. Moreover, new therapeutic approaches to combat PCSCs are presented with the aim to achieve an improved outcome for patients with PC.

The Notch1 gene may control cell chemoresistance in esophageal squamous cell cancer

BACKGROUND

In our previous study, missense mutations in the Notch1 gene were found in chemotherapy-resistant esophageal squamous cell cancer (ESCC) patients. In this study, we explored changes in the interaction between Notch1 and DLL4 resulting from missense mutations.

METHODS

Bioinformatics analysis was performed to assess and compare the different biological structures and functions of wild type (WT) and mutation type (MT) sequences of Notch1. A genetic information search was performed, and the results were analyzed using in silico modeling. Homology modeling of the Notch1 protein was carried out using Swiss-Model software, and modeling of site-directed mutations was carried out using PyMOL software to observe the protein structure. The Notch1-DLL4 ligand-receptor complex protein model was constructed, Wincoot software was used to determine site-directed mutations, and a protein-ligand interaction profiler (PLIP) was used to calculate the noncovalent interactions in the complex.

RESULTS

The mutation site was located in the region where Notch1 binds to DLL4. A careful examination of the in silico structural model revealed that the mutation caused an alteration in the surface charge, and the water-bridge bonds of the interaction between Notch1-DLL4 increased in number from 5 to 7.

CONCLUSIONS

Notch1 gene missense mutation leads to an increase in the number of water-bridge bonds, thus enhancing the Notch1-DLL4 interaction, which may lead to tighter Notch1-DLL4 binding, either making the pathway easier to activate or increasing the length of time it is active.

Long non-coding RNAs in the doxorubicin resistance of cancer cells

Chemotherapy is the main treatment used for cancer patients failing surgery. Doxorubicin (DOX) is a well-known chemotherapeutic agent capable of suppressing proliferation in cancer cells and triggering apoptosis via inhibiting topoisomerase II activity and producing DNA breaks. This activity of DOX restrains mitosis and cell cycle progression. However, frequent application of DOX results in the emergence of resistance in the cancer cells. It seems that genetic and epigenetic factors can provide DOX resistance of cancer cells. Long non-coding RNAs (lncRNAs) are a subcategory of non-coding RNAs with role in the regulation of several cellular processes such as proliferation, migration, differentiation and apoptosis. LncRNA dysregulation has been associated with chemoresistance, and this profile occurs upon DOX treatment of cancer. In the present review, we focus on the role of lncRNAs in mediating DOX resistance and discuss the molecular pathways and mechanisms. LncRNAs can drive DOX resistance via activating pathways such as NF-κB, PI3K/Akt, Wnt, and FOXC2. Some lncRNAs can activate protective autophagy in response to the stress caused by DOX, which mediates resistance. In contrast, there are other lncRNAs involved in the sensitivity of cancer cells to DOX, such as GAS5, PTCSC3 and FENDRR. Some anti-tumor agents such as polydatin can regulate the expression of lncRNAs, enhancing DOX sensitivity. Overall, lncRNAs are potential players in DOX resistance, and their identification and targeting are of importance in chemosensitivity. Furthermore, these findings can be translated into clinical for treatment of cancer patients.

Taxanes in cancer treatment: Activity, chemoresistance and its overcoming

Since 1984, when paclitaxel was approved by the FDA for the treatment of advanced ovarian carcinoma, taxanes have been widely used as microtubule-targeting antitumor agents. However, their historic classification as antimitotics does not describe all their functions. Indeed, taxanes act in a complex manner, altering multiple cellular oncogenic processes including mitosis, angiogenesis, apoptosis, inflammatory response, and ROS production. On the one hand, identification of the diverse effects of taxanes on oncogenic signaling pathways provides opportunities to apply these cytotoxic drugs in a more rational manner. On the other hand, this may facilitate the development of novel treatment modalities to surmount anticancer drug resistance. In the latter respect, chemoresistance remains a major impediment which limits the efficacy of antitumor chemotherapy. Taxanes have shown impact on key molecular mechanisms including disruption of mitotic spindle, mitosis slippage and inhibition of angiogenesis. Furthermore, there is an emerging contribution of cellular processes including autophagy, oxidative stress, epigenetic alterations and microRNAs deregulation to the acquisition of taxane resistance. Hence, these two lines of findings are currently promoting a more rational and efficacious taxane application as well as development of novel molecular strategies to enhance the efficacy of taxane-based cancer treatment while overcoming drug resistance. This review provides a general and comprehensive picture on the use of taxanes in cancer treatment. In particular, we describe the history of application of taxanes in anticancer therapeutics, the synthesis of the different drugs belonging to this class of cytotoxic compounds, their features and the differences between them. We further dissect the molecular mechanisms of action of taxanes and the molecular basis underlying the onset of taxane resistance. We further delineate the possible modalities to overcome chemoresistance to taxanes, such as increasing drug solubility, delivery and pharmacokinetics, overcoming microtubule alterations or mitotic slippage, inhibiting drug efflux pumps or drug metabolism, targeting redox metabolism, immune response, and other cellular functions.

Mechanisms of docetaxel resistance in prostate cancer: The key role played by miRNAs

One of the main problems with the treatment of metastatic prostate cancer is that, despite an initial positive response, the majority of patients develop resistance and progress. In particular, the resistance to docetaxel, the gold standard therapy for metastatic prostate cancer since 2010, represents one of the main factors responsible for the failure of prostate cancer therapy. According to the present knowledge, different processes contribute to the appearance of docetaxel resistance and non-coding RNA seems to play a relevant role in them. In this review, a comprehensive overview of the miRNA network involved in docetaxel resistance is described, highlighting the pathway/s affected by their activity.

Molecular mechanisms of docetaxel resistance in prostate cancer

Docetaxel (DTX) chemotherapy offers excellent initial response and confers significant survival benefit in patients with castration-resistant prostate cancer (CRPC). However, the clinical utility of DTX is compromised when primary and acquired resistance are encountered. Therefore, a more thorough understanding of DTX resistance mechanisms may potentially improve survival in patients with CRPC. This review focuses on DTX and discusses its mechanisms of resistance. We outline the involvement of tubulin alterations, androgen receptor (AR) signaling/AR variants, ERG rearrangements, drug efflux/influx, cancer stem cells, centrosome clustering, and phosphoinositide 3-kinase/AKT signaling in mediating DTX resistance. Furthermore, potential biomarkers for DTX treatment and therapeutic strategies to circumvent DTX resistance are reviewed.

Inhibition of the Lysophosphatidylinositol Transporter ABCC1 Reduces Prostate Cancer Cell Growth and Sensitizes to Chemotherapy

Expression of ATP-binding cassette (ABC) transporters has long been implicated in cancer chemotherapy resistance. Increased expression of the ABCC subfamily transporters has been reported in prostate cancer, especially in androgen-resistant cases. ABCC transporters are known to efflux drugs but, recently, we have demonstrated that they can also have a more direct role in cancer progression. The pharmacological potential of targeting ABCC1, however, remained to be assessed. In this study, we investigated whether the blockade of ABCC1 affects prostate cancer cell proliferation using both in vitro and in vivo models. Our data demonstrate that pharmacological inhibition of ABCC1 reduced prostate cancer cell growth in vitro and potentiated the effects of Docetaxel in vitro and in mouse models of prostate cancer in vivo. Collectively, these data identify ABCC1 as a novel and promising target in prostate cancer therapy.

Inhibition of Notch pathway enhances the anti-tumor effect of docetaxel in prostate cancer stem-like cells

Background

Prostate cancer stem-like cells (PCSCs) likely participate in tumor progression and recurrence and demonstrate resistance to chemotherapy. The Notch pathway plays a role in the maintenance of the stemness in PCSCs. This study aimed to investigate the efficacy of Notch signaling inhibition as an adjuvant to docetaxel (DOX) in PCSCs.

Methods

PCSCs derived from the PC-3 cell line were examined for Notch-1 expression. The effect of Notch inhibition on response to DOX was evaluated in PCSCs in vitro and in murine models using a γ-secretase inhibitor (GSI), PF-03084014. Impacts on cell proliferation, apoptosis, cell cycle, and sphere formation were evaluated.

Results

PC-3 PCSCs expressed elevated Notch-1 mRNA compared with PC-3 parental cells. The combination of GSI with DOX promoted DOX-induced cell growth inhibition, apoptosis, cell cycle arrest, and sphere formation in PCSCs. In nude mice bearing PC-3 PCSC-derived tumors, the combination of GSI and DOX reduced the tumor growth, which was associated with the decreased Notch-1 expression in tumor tissues.

Conclusions

These results reveal that inhibition of the Notch pathway enhances the anti-tumor effect of DOX in PC-3 PCSCs, and suggest that Notch inhibition may have clinical benefits in targeting PCSCs.

Identification of Novel Rare ABCC1 Transporter Mutations in Tumor Biopsies of Cancer Patients

The efficiency of chemotherapy drugs can be affected by ATP-binding cassette (ABC) transporter expression or by their mutation status. Multidrug resistance is linked with ABC transporter overexpression. In the present study, we performed rare mutation analyses for 12 ABC transporters related to drug resistance (ABCA2, -A3, -B1, -B2, -B5, -C1, -C2, -C3, -C4, -C5, -C6, -G2) in a dataset of 18 cancer patients. We focused on rare mutations resembling tumor heterogeneity of ABC transporters in small tumor subpopulations. Novel rare mutations were found in ABCC1, but not in the other ABC transporters investigated. Diverse ABCC1 mutations were found, including nonsense mutations causing premature stop codons, and compared with the wild-type protein in terms of their protein structure. Nonsense mutations lead to truncated protein structures. Molecular docking and heat map analyses of ABCC1/MRP1 pointed out that Lys498* appeared in a separate cluster branch due to the large deletion, leading to a massive disruption in the protein conformation. The resulting proteins, which are nonfunctional due to nonsense mutations in tumors, offer a promising chemotherapy strategy since tumors with nonsense mutations may be more sensitive to anticancer drugs than wild-type ABCC1-expressing tumors. This could provide a novel tumor-specific toxicity strategy and a way to overcome drug resistance.

Trop2 Promotes Multidrug Resistance by Regulating Notch1 Signaling Pathway in Gastric Cancer Cells

BACKGROUND Chemotherapy is widely used in gastric cancer treatment, but multidrug resistance remains a leading cause of chemotherapy failure. Trop2 is highly expressed in gastric tumor tissues and greatly influences cancer progression. However, little is known about the relationship between Trop2 and drug resistance in gastric cancer. MATERIAL AND METHODS In the present study, Trop2 was knocked down in BGC823 cells and overexpressed in HGC27. CCK-8 assay was performed to explore the relationship of Trop2 expression and cell proliferation treated with anticancer drugs. Flow cytometry was performed to assess the relationship between Trop2 and cell apoptosis after chemotherapy. Subcutaneous xenograft models were generated to explore the curative effect of DDP to GC in vivo. MRP1 and Notch1 expressions were assessed by Western blot. RESULTS Trop2 decreased cell proliferation inhibition and apoptosis after chemotherapeutic treatments. DDP showed stronger therapeutic effects on Trop2-knockdown tumor than control in vivo. MRP1 and Notch1 signaling pathway were confirmed to participate in Trop2-induced drug resistance. CONCLUSIONS Our findings suggest that Trop2 promotes the resistance of gastric cancer to chemotherapy by activating the Notch1 pathway.

Allyl isothiocyanate upregulates MRP1 expression through Notch1 signaling in human bronchial epithelial cells

Multidrug resistance associated protein-1 (MRP1) and Notch signaling are closely related and both play a critical role in chronic obstructive pulmonary disease (COPD) establishment and progression. The aim of our work was to test whether Notch1 is involved in allyl isothiocyanate (AITC) induced MRP1 expression. We used cigarette smoke extract (CSE) to simulate the smoking microenvironment in vitro. The results demonstrated that CSE led to apoptosis as well as reduced the expression of Notch1, Hes1, and MRP1, while AITC significantly reversed this downregulation. Transfected with Notch1 siRNA downregulated MRP1 expression and activity, aggravated the suppression effect by CSE, and abolished the AITC-induced Notch1, Hes1, and MRP1 expression. Validation of the correlation between Notch1 and MRP1 was implemented by gel-shift assays (electrophoretic mobility shift assay). The result revealed an interaction between a specific promoter region of MRP1 and the intracellular domain of Notch1. In conclusion, Notch1 signaling positively regulated MRP1 in 16HBE cells and AITC induced MRP1 expression and function may be attributed to Notch1 signaling. These findings show that Notch1 and MRP1 might have a potential protective effect in the COPD process and become a new therapeutic target for COPD or other lung diseases. It also provides a theoretical basis for the therapeutic effects of AITC.

Doxorubicin as a fluorescent reporter identifies novel MRP1 (ABCC1) inhibitors missed by calcein-based high content screening of anticancer agents

Multidrug resistance protein 1 (MRP1/ABCC1) actively transports a variety of drugs, toxic molecules and important physiological substrates across the plasma membrane. It can confer broad-spectrum multidrug resistance and can decrease the bioavailability of many important drugs. Substrates of MRP1 include anti-cancer agents, antibiotics, antivirals, antidepressants and anti-inflammatory drugs. Using calcein as a fluorescent reporter in a high content uptake assay, we recently reported the identification of 12 MRP1 inhibitors after screening an anti-cancer library of 386 compounds. Here, we describe the development of a new high content imaging-based uptake assay using doxorubicin as a fluorescent reporter. Screening the same anti-cancer library of 386 compounds, the new assay identified a total of 28 MRP1 inhibitors including 16 inhibitors that have not been previously reported as inhibitors of MRP1. Inhibition of MRP1 activity was confirmed using flow cytometry and confocal microscopy-based transport assays. Six drugs (afatinib, celecoxib, doramapimod, mifepristone, MK-2206 and rosiglitazone) were evaluated for their ability to reverse resistance of MRP1-overexpressing H69AR lung cancer cells against vincristine, doxorubicin and etoposide. Mifepristone and doramapimod were most effective in reversal of resistance against vincristine while mifepristone and rosiglitazone were most successful in resensitizing H69AR cells against doxorubicin. Furthermore, resistance towards etoposide was completely reversed in the presence of celecoxib or doramapimod. Selected drugs were also evaluated for resistance reversal in HEK cells that overexpress P-glycoprotein or breast cancer resistance protein. Our results indicate mifepristone and doramapimod as pan inhibitors of these three drug transporters while celecoxib exhibited selective MRP1 inhibition. Together, our findings signify the importance of MRP1 in drug discovery and demonstrate the effectiveness and value of doxorubicin-based high content screening approach. Anti-cancer agents that exhibit MRP1 inhibition may be used to reverse multidrug resistance or to improve the efficacy and reduce the toxicity of various cancer chemotherapies. On the other hand, anti-cancer drugs that did not interact with MRP1 carry a low risk for developing MRP1-mediated resistance.

Cellular and Molecular Mechanisms Underlying Prostate Cancer Development: Therapeutic Implications

Prostate cancer is the most frequent nonskin cancer and second most common cause of cancer-related deaths in man. Prostate cancer is a clinically heterogeneous disease with many patients exhibiting an aggressive disease with progression, metastasis, and other patients showing an indolent disease with low tendency to progression. Three stages of development of human prostate tumors have been identified: intraepithelial neoplasia, adenocarcinoma androgen-dependent, and adenocarcinoma androgen-independent or castration-resistant. Advances in molecular technologies have provided a very rapid progress in our understanding of the genomic events responsible for the initial development and progression of prostate cancer. These studies have shown that prostate cancer genome displays a relatively low mutation rate compared with other cancers and few chromosomal loss or gains. The ensemble of these molecular studies has led to suggest the existence of two main molecular groups of prostate cancers: one characterized by the presence of ERG rearrangements (~50% of prostate cancers harbor recurrent gene fusions involving ETS transcription factors, fusing the 5' untranslated region of the androgen-regulated gene TMPRSS2 to nearly the coding sequence of the ETS family transcription factor ERG) and features of chemoplexy (complex gene rearrangements developing from a coordinated and simultaneous molecular event), and a second one characterized by the absence of ERG rearrangements and by the frequent mutations in the E3 ubiquitin ligase adapter SPOP and/or deletion of CDH1, a chromatin remodeling factor, and interchromosomal rearrangements and SPOP mutations are early events during prostate cancer development. During disease progression, genomic and epigenomic abnormalities accrued and converged on prostate cancer pathways, leading to a highly heterogeneous transcriptomic landscape, characterized by a hyperactive androgen receptor signaling axis.

Major vault protein is a direct target of Notch1 signaling and contributes to chemoresistance in triple-negative breast cancer cells

Resistance to chemotherapy remains a significant problem in the treatment of breast cancer, especially for triple-negative breast cancer (TNBC), in which standard systemic therapy is currently limited to chemotherapeutic agents. Our study aimed to better understand the molecular mechanisms that lead to failure of chemotherapy in TNBC. Herein, we observed elevated expression of Notch1 and major vault protein (MVP) in MDA-MB-231DDPR cells compared to their parental counterparts. We demonstrated that Notch1 could positively regulate the expression of MVP. Also, Notch1 intracellular domain (ICD) was capable of binding to CBF-1 on the promoter of MVP to drive its transcription, resulting in activation of AKT pathway and promoting the progress of epithelial to mesenchymal transition (EMT). Conversely, silencing of Notch1 and MVP suppressed AKT pathway, reduced EMT and enhanced the sensitivity of TNBC cells to cisplatin and doxorubicin. Survival analysis indicated that the MVP was closely related to shorter recurrence-free survival (RFS) in patients with TNBC. Collectively, this study provides evidence that Notch1 activates AKT pathway and promotes EMT partly through direct activation of MVP. Targeting Notch1/MVP pathway appears to have potential in overcoming chemoresistance in TNBC.

miR-1301-3p promotes prostate cancer stem cell expansion by targeting SFRP1 and GSK3β

Cancer stem cells promote tumor progression, drug-resistance, and relapse, and many microRNAs (miRNAs) play critical roles in the expansion of cancer stem cells. In the present study, we investigated the role of miR-1301-3p in the expansion of prostate cancer stem cells; miR-1301-3p was significantly upregulated in prostate cancer cells and tissues compared with normal prostate cells and tissues. Sphere formation and side population assays suggested that miR-1301-3p promoted the expansion of prostate cancer stem cells, and increased the expression of prostate cancer stem cell-associated genes, such as OCT4, SOX2, NANOG, CD44, KLF4, c-MYC, and MMP2. MiR-1301-3p targeted Wnt pathway inhibitors, GSK3β and SFRP1, and inhibited their expression by directly binding to their 3' untranslated regions. TOP/FOP luciferase assays suggested that miR-1301-3p activated the Wnt pathway, which was confirmed by increased β-catenin expression in the nucleus. Furthermore, the miR-1301-3p level correlated negatively with GSK3β and SFRP1 in prostate cancer tissues. In summary, we found that miR-1301-3p promoted the expansion of prostate cancer stem cells by inhibiting GSK3β and SFRP1, and activating the Wnt pathway.

Single-nucleotide polymorphisms of stemness genes predicted to regulate RNA splicing, microRNA and oncogenic signaling are associated with prostate cancer survival

Prostate cancer (PCa) is a clinically and molecularly heterogeneous disease, with variation in outcomes only partially predicted by grade and stage. Additional tools to distinguish indolent from aggressive disease are needed. Phenotypic characteristics of stemness correlate with poor cancer prognosis. Given this correlation, we identified single-nucleotide polymorphisms (SNPs) of stemness-related genes and examined their associations with PCa survival. SNPs within stemness-related genes were analyzed for association with overall survival of PCa in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Significant SNPs predicted to be functional were selected for linkage disequilibrium analysis and combined and stratified analyses. Identified SNPs were evaluated for association with gene expression. SNPs of CD44 (rs9666607), ABCC1 (rs35605 and rs212091) and GDF15 (rs1058587) were associated with PCa survival and predicted to be functional. A role for rs9666607 of CD44 and rs35605 of ABCC1 in RNA splicing regulation, rs212091 of ABCC1 in miRNA binding site activity and rs1058587 of GDF15 in causing an amino acid change was predicted. These SNPs represent potential novel prognostic markers for overall survival of PCa and support a contribution of the stemness pathway to PCa patient outcome.

Cancer stem cells and hypoxia-inducible factors (Review)

Cancer stem cells (CSCs), also known as tumor-initiating cells, are a subpopulation of tumor cells that exhibit properties similar to those of normal stem cells. Oxygen is an important regulator of cellular metabolism; hypoxia-inducible factors (HIFs) mediate metabolic switches in cells in hypoxic environments. Hypoxia clearly has the potential to exert a significant effect on the maintenance and evolution of CSCs. Both HIF‑1α and HIF‑2α may contribute to the regulation of cellular adaptation to hypoxia and resistance to cancer therapies. This review provides an overview of the roles of HIFs in CSCs. HIF‑1α and HIF‑2α have significant prognostic and predictive value in the clinic and the concept of personalized medicine should be applied in designing clinical trials for HIF inhibitors.

Replication-incompetent gammaretroviral and lentiviral vector-based insertional mutagenesis screens identify prostate cancer progression genes

Replication-incompetent gammaretroviral (γRV) and lentiviral (LV) vectors have both been used in insertional mutagenesis screens to identify cancer drivers. In this approach the vectors stably integrate in the host cell genome and induce cancers by dysregulating nearby genes. The cells that contain a retroviral vector provirus in or near a proto-oncogene or tumor suppressor are preferentially enriched in a tumor. γRV and LV vectors have different integration profiles and genotoxic potential, making them potentially complementary tools for insertional mutagenesis screens. We performed screens using both γRV and LV vectors to identify driver genes that mediate progression of androgen-independent prostate cancer (AIPC) using a xenotransplant mouse model. Vector transduced LNCaP cells were injected orthotopically into the prostate gland of immunodeficient mice. Mice that developed tumors were castrated to create an androgen-deficient environment and metastatic tumors that developed were analyzed. A high-throughput modified genomic sequencing PCR (MGS-PCR) approach identified the positions of vector integrations in these metastatic tumors. OR2A14, FER1L6, TAOK3, MAN1A2, MBNL2, SERBP1, PLEKHA2, SPTAN1, ADAMTS1, SLC30A5, ABCC1, SLC7A1 and SLC25A24 were identified as candidate prostate cancer (PC) progression genes. TAOK3 and ABCC1 expression in PC patients predicted the risk of recurrence after androgen deprivation therapy. Our data shows that γRV and LV vectors are complementary approaches to identify cancer driver genes which may be promising potential biomarkers and therapeutic targets.

MRP1-CD28 bi-specific oligonucleotide aptamers: target costimulation to drug-resistant melanoma cancer stem cells

In this work we show a clinically feasible strategy to convert in situ the own tumor into an endogenous vaccine by coating the melanoma cancerous cells with CD28 costimulatory ligands. This therapeutic approach is aimed at targeting T-cell costimulation to chemotherapy-resistant tumors which are refractory and been considered as untreatable cancers. These tumors are usually defined by an enrichment of cancer stem cells and characterized by the higher expression of chemotherapy-resistant proteins. In this work we develop the first aptamer that targets chemotherapy-resistant tumors expressing MRP1 through a novel combinatorial peptide-cell SELEX. With the use of the MRP1 aptamer we engineer a MRP1-CD28 bivalent aptamer that is able to bind MRP1-expressing tumors and deliver the CD28 costimulatory signal to tumor-infiltrating lymphocytes. The bi-specific aptamer is able to enhance costimulation in chemotherapy-resistant tumors. Melanoma-bearing mice systemically treated with MRP1-CD28 bivalent aptamer show reduced growth, thus proving an improved mice survival.

Besides, we have designed a technically feasible and translational whole-cell vaccine (Aptvax). Disaggregated cells from tumors can be directly decorated with costimulatory ligand aptamers to generate the vaccine Aptvax. CD28Aptvax made of irradiated tumor cells coated with the CD28-agonistic aptamer attached to MRP1 elicits a strong tumor- cell immune response against melanoma tumors reducing tumor growth.

High expression of TROP2 characterizes different cell subpopulations in androgen-sensitive and androgen-independent prostate cancer cells

Progression of castration-resistant tumors is frequent in prostate cancer. Current systemic treatments for castration-resistant prostate cancer only produce modest increases in survival time and self-renewing Tumor-Initiating Cells (TICs) are suspected to play an important role in resistance to these treatments. However it remains unclear whether the same TICs display both chemo-resistance and self-renewing abilities throughout progression from early stage lesions to late, castration resistant tumors. Here, we found that treatment of mice bearing LNCaP-derived xenograft tumors with cytotoxic (docetaxel) and anti-androgen (flutamide) compounds enriched for cells that express TROP2, a putative TIC marker. Consistent with a tumor-initiating role, TROP2^high cells from androgen-sensitive prostate cancer cell lines displayed an enhanced ability to re-grow in culture following treatment with taxane-based chemotherapy with or without androgen blockade. TROP2 down-regulation in these cells reduced their ability to recur after treatment with docetaxel, in the presence or absence of flutamide. Accordingly, in silico analysis of published clinical data revealed that prostate cancer patients with poor prognosis exhibit significantly elevated TROP2 expression level compared to low-risk patients, particularly in the case of patients diagnosed with early stage tumors. In contrast, in androgen-independent prostate cancer cell lines, TROP2^high cells did not exhibit a differential treatment response but were characterized by their high self-renewal ability. Based on these findings we propose that high TROP2 expression identifies distinct cell sub-populations in androgen-sensitive and androgen-independent prostate tumors and that it may be a predictive biomarker for prostate cancer treatment response in androgen-sensitive tumors.

Bcl-2 Antiapoptotic Family Proteins and Chemoresistance in Cancer

Cancer is a daunting global problem confronting the world's population. The most frequent therapeutic approaches include surgery, chemotherapy, radiotherapy, and more recently immunotherapy. In the case of chemotherapy, patients ultimately develop resistance to both single and multiple chemotherapeutic agents, which can culminate in metastatic disease which is a major cause of patient death from solid tumors. Chemoresistance, a primary cause of treatment failure, is attributed to multiple factors including decreased drug accumulation, reduced drug-target interactions, increased populations of cancer stem cells, enhanced autophagy activity, and reduced apoptosis in cancer cells. Reprogramming tumor cells to undergo drug-induced apoptosis provides a promising and powerful strategy for treating resistant and recurrent neoplastic diseases. This can be achieved by downregulating dysregulated antiapoptotic factors or activation of proapoptotic factors in tumor cells. A major target of dysregulation in cancer cells that can occur during chemoresistance involves altered expression of Bcl-2 family members. Bcl-2 antiapoptotic molecules (Bcl-2, Bcl-xL, and Mcl-1) are frequently upregulated in acquired chemoresistant cancer cells, which block drug-induced apoptosis. We presently overview the potential role of Bcl-2 antiapoptotic proteins in the development of cancer chemoresistance and overview the clinical approaches that use Bcl-2 inhibitors to restore cell death in chemoresistant and recurrent tumors.

Regulation of ABCG2 by nuclear factor kappa B affects the sensitivity of human lung adenocarcinoma A549 cells to arsenic trioxide

Arsenic trioxide (As₂O₃) is successfully used as an anticancer agent against acute promyelocytic leukemia and some solid tumors. However, the application of As₂O₃ is largely limited by its drug resistance in the treatment of non-small cell lung carcinoma (NSCLC). Therefore, it is an urgent task to enhance the sensitivity of lung cancer cells to As₂O₃. In this study, using human lung adenocarcinoma A549 cells as a cell culture model, we demonstrated that an adenosine triphosphate binding cassette (ABC) transporter, ABCG2, was significantly increased by As₂O₃ treatment, while other ABC transporters, ABCB1 and ABCC1 showed no remarkable change in the response to As₂O₃. After inhibition of ABCG2 by its specific inhibitor, the drug sensitivity of As₂O₃ to A549 cells was significantly enhanced, manifested by decreased cell viability and colony formation as well as the increased ROS production and cell apoptosis. To further understand the molecular mechanism underlying the elevation of ABCG2 expression in As₂O₃-treated cells, we detected the activation state of nuclear factor kappa B (NF-κB) pathway and its relationship with ABCG2 expression. Our results revealed that the increased expression of ABCG2 was regulated by NF-κB, and thus affecting the cell death of As₂O₃-treated A549 cells. These findings indicate that inhibition of NF-κB/ABCG2 pathway by specific inhibitors may be a new strategy for the improvement of As₂O₃ sensitivity in NSCLC treatment.

LncRNA FENDRR sensitizes doxorubicin-resistance of osteosarcoma cells through down-regulating ABCB1 and ABCC1

Long noncoding RNAs (LncRNAs) act as crucial regulators in various cancers including osteosarcoma (OS), yet their potential roles and molecular mechanisms in OS chemoresistance remain unclear. In the present study, we investigated the role and potential regulatory mechanism of the most down-regulated expressed lncRNA, FENDRR screened by our previous lncRNA microarray analysis between the paired doxorubicin-resistant and sensitive human osteosarcoma cell lines (MG63/DXR vs MG63). FENDRR expression was down-regulated in the doxorubicin-resistant OS cell lines and tissues and negatively correlated to the poor prognosis of OS patients. Overexpression of FENDRR suppressed doxorubicin-resistance, G2/M phase of cell cycle, and promoted cell apoptosis of osteosarcoma cells in vitro and tumor growth in vivo whereas FENDRR knockdown had the opposite effects. In addition, we found that FENDRR was mainly located in the cytoplasm and could regulate the drug resistance of osteosarcoma cells by negatively affecting posttranscriptional expression of ABCB1 and ABCC1. Together, our study demonstrated that lncRNA FENDRR may act as an inhibitory molecule of doxorubicin-resistance through down-regulating the expression of ABCB1 and ABCC1 genes in osteosarcoma cells. These findings may extend the function of FENDRR in tumor progression and provide a novel target for reversing OS chemoresistance.

The Notch-1 receptor in prostate tumorigenesis

The Notch signalling pathway plays a fundamental role in tissue development due to its involvement in cell fate determination and postnatal tissue differentiation. Its capacity to regulate cell growth and development has been linked to the occurrence of several cancers including that of the prostate. The transmembrane receptor Notch-1 of this pathway has been linked to the oncogenic role of Notch signalling in prostate adenocarcinoma. Other studies have suggested a tumour suppressive function for Notch-1. This review focuses on the role of Notch-1 in prostate cancer development and maintenance and relates this to the fundamental role of Notch in normal prostate development. The current understanding of the aberrant Notch signalling characteristic of prostate cancer is discussed, and recent therapeutic advances in this field are presented.

AXIN2 expression predicts prostate cancer recurrence and regulates invasion and tumor growth

BACKGROUND

Treatment of prostate cancer (PCa) may be improved by identifying biological mechanisms of tumor growth that directly impact clinical disease progression. We investigated whether genes associated with a highly tumorigenic, drug resistant, progenitor phenotype impact PCa biology and recurrence.

METHODS

Radical prostatectomy (RP) specimens (±disease recurrence, N = 276) were analyzed by qRT-PCR to quantify expression of genes associated with self-renewal, drug resistance, and tumorigenicity in prior studies. Associations between gene expression and PCa recurrence were confirmed by bootstrap internal validation and by external validation in independent cohorts (total N = 675) and in silico. siRNA knockdown and lentiviral overexpression were used to determine the effect of gene expression on PCa invasion, proliferation, and tumor growth.

RESULTS

Four candidate genes were differentially expressed in PCa recurrence. Of these, low AXIN2 expression was internally validated in the discovery cohort. Validation in external cohorts and in silico demonstrated that low AXIN2 was independently associated with more aggressive PCa, biochemical recurrence, and metastasis-free survival after RP. Functionally, siRNA-mediated depletion of AXIN2 significantly increased invasiveness, proliferation, and tumor growth. Conversely, ectopic overexpression of AXIN2 significantly reduced invasiveness, proliferation, and tumor growth.

CONCLUSIONS

Low AXIN2 expression was associated with PCa recurrence after RP in our test population as well as in external validation cohorts, and its expression levels in PCa cells significantly impacted invasiveness, proliferation, and tumor growth. Given these novel roles, further study of AXIN2 in PCa may yield promising new predictive and therapeutic strategies.

The role of ATP-binding cassette transporter genes in the progression of prostate cancer

BACKGROUND

Prostate cancer (PCa) is the most commonly diagnosed neoplasm and the second leading cause of cancer-related death among men in developed countries. There is no clear evidence showing the success of current screening tests in reducing mortality of PCa. In this study, we aimed to profile expressions of nine ABC transporters, ABCA5, ABCB1, ABCB6, ABCC1, ABCC2, ABCC3, ABCC5, ABCC10, and ABCF2, in recurrent, non-recurrent PCa and normal prostate tissues.

METHODS

A total of 77 (39 recurrent, 38 non-recurrent) radical prostatectomy and 20 normal prostate samples, obtained from Baylor College of Medicine Prostate Cancer program, were included into the study and divided into two independent groups as test and validation sample sets. Differential expression of selected ABC transporters was assessed using quantitative real-time PCR (qRT-PCR). Pearson's correlation test, receiver operating characteristics (ROC) analysis and Kaplan-Meier test were used for statistical analysis.

RESULTS

QRT-PCR results demonstrated the elevated expression of ABCA5, ABCB1, ABCB6, ABCC1, and ABCC2 as well as reduced expression of ABCC3 in PCa samples compared to normal prostate tissues. In addition, we found deregulation of ABCB1, ABCB6, ABCC3, and ABCC10 in recurrent PCa samples and validated differential expression of ABCB6, ABCC3, and ABCC10 in recurrent PCa compared to non-recurrent PCa. Pearson's correlation, ROC and Kaplan-Meier analysis revealed the power of these three ABC transporters for estimating prognosis of PCa.

CONCLUSIONS

We demonstrated differential expression of ABC transporters both in tumor versus normal and recurrent versus non-recurrent comparisons. Our data suggest ABCB6, ABCC3, and ABCC10 as valuable predictors of PCa progression.

Mutual regulation and targeting of multidrug resistance and cancer stem phenotype

Targeting stemness mechanisms leads to the suppression of ABC transporter activity and elimination of CSCs.

MRP1 and its role in anticancer drug resistance

The phenomenon of multidrug resistance (MDR) in cancer is associated with the overexpression of the ATP-binding cassette (ABC) transporter proteins, including multidrug resistance-associated protein 1 (MRP1) and P-glycoprotein. MRP1 plays an active role in protecting cells by its ability to efflux a vast array of drugs to sub-lethal levels. There has been much effort in elucidating the mechanisms of action, structure and substrates and substrate binding sites of MRP1 in the last decade. In this review, we detail our current understanding of MRP1, its clinical relevance and highlight the current environment in the search for MRP1 inhibitors. We also look at the capacity for the rapid intercellular transfer of MRP1 phenotype from spontaneously shed membrane vesicles known as microparticles and discuss the clinical and therapeutic significance of this in the context of cancer MDR.

Chemotherapy induces Notch1-dependent MRP1 up-regulation, inhibition of which sensitizes breast cancer cells to chemotherapy

Background

Multi-drug Resistance associated Protein-1 (MRP1) can export chemotherapeutics from cancer cells and is implicated in chemoresistance, particularly as is it known to be up-regulated by chemotherapeutics. Our aims in this study were to determine whether activation of Notch signalling is responsible for chemotherapy-induced MRP1 expression Notch in breast cancers, and whether this pathway can be manipulated with an inhibitor of Notch activity.

Methods

MRP1 and Notch1 were investigated in 29 patients treated with neoadjuvant chemotherapy (NAC) for breast cancer, using immunohistochemistry on matched biopsy (pre-NAC) and surgical samples (post-NAC). Breast epithelial cell cultures (T47D, HB2) were treated with doxorubicin in the presence and absence of functional Notch1, and qPCR, siRNA, Western blots, ELISAs and flow-cytometry were used to establish interactions.

Results

In clinical samples, Notch1 was activated by neoadjuvant chemotherapy (Wilcoxon signed-rank p < 0.0001) and this correlated with induction of MRP1 expression (rho = 0.6 p = 0.0008). In breast cell lines, doxorubicin induced MRP1 expression and function (non-linear regression p < 0.004). In the breast cancer line T47D, doxorubicin activated Notch1 and, critically, inhibition of Notch1 activation with the γ-secretase inhibitor DAPT abolished the doxorubicin-induced increase in MRP1 expression and function (t-test p < 0.05), resulting in enhanced cellular retention of doxorubicin and increased doxorubicin-induced apoptosis (t-test p = 0.0002). In HB2 cells, an immortal but non-cancer derived breast cell line, Notch1-independent MRP1 induction was noted and DAPT did not enhance doxorubicin-induced apoptosis.

Conclusions

Notch inhibitors may have potential in sensitizing breast cancer cells to chemotherapeutics and therefore in tackling chemoresistance.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1625-y) contains supplementary material, which is available to authorized users.

A literature mining-based approach for identification of cellular pathways associated with chemoresistance in cancer

Chemoresistance is a major obstacle to the successful treatment of many human cancer types. Increasing evidence has revealed that chemoresistance involves many genes and multiple complex biological mechanisms including cancer stem cells, drug efflux mechanism, autophagy and epithelial-mesenchymal transition. Many studies have been conducted to investigate the possible molecular mechanisms of chemoresistance. However, understanding of the biological mechanisms in chemoresistance still remains limited. We surveyed the literature on chemoresistance-related genes and pathways of multiple cancer types. We then used a curated pathway database to investigate significant chemoresistance-related biological pathways. In addition, to investigate the importance of chemoresistance-related markers in protein-protein interaction networks identified using the curated database, we used a gene-ranking algorithm designed based on a graph-based scoring function in our previous study. Our comprehensive survey and analysis provide a systems biology-based overview of the underlying mechanisms of chemoresistance.

Overexpression of Notch1 is associated with the progression of cervical cancer

Cervical cancer is the third most common malignancy worldwide, accounting for 250,000 mortalities annually. Notch1, an important regulator of cell-fate decisions and differentiation, has been found to be overexpressed in certain types of cancer. However, the role of Notch1 in cervical carcinogenesis remains unclear. In the present study, immunohistochemical staining and western blot analysis revealed that Notch1 expression was significantly higher in cervical cancer tissues than that in normal cervical tissues. Furthermore, statistical analysis revealed that Notch1 expression was significantly associated with tumor differentiation and tumor stage. These findings indicated that Notch1 expression was associated with the progression of cervical cancer. The western blot assay also identified a positive correlation between Notch1 and Ki67 expression in cervical cancer tissues, which suggested that Notch1 expression may be associated with the proliferation of cervical cancer. In order to further evaluate the specific role of Notch1 in cervical cancer progression, its expression in SiHa and C33A cells was knocked down using small interfering RNA. It was revealed that the knockdown of Notch1 in SiHa and C33A cells resulted in significant inhibition of cell proliferation and colony formation in vitro. These results indicated that Notch1 was able to promote cell proliferation in cervical cancer. In conclusion, the results of the present study indicated that Notch1 may function as a promoter in cervical carcinogenesis.