Improved Cisplatin Sensitivity Research Articles

Reactivation of methylation-silenced PAX1 inhibits cervical cancer proliferation and migration via the WNT/TIMELESS pathway.

Although aberrant methylation of PAX1 is closely associated with cervical cancer (CC), PAX1 methylation (PAX1m) and its role in CC remain to be elucidated. Here, we clarified the biological function of PAX1 in CC. First, PAX1m in ThinPrep cytologic test samples was measured via quantitative methylation-specific PCR. The results showed that PAX1 promoter methylation levels were significantly increased in CC patients (p < 0.001). We also found that PAX1 promoter methylation levels were positively correlated with tumor purity but negatively correlated with immune-infiltration via public databases. Then, CRISPR-based methylation perturbation tools (dCas9-Tet1) were constructed to further demonstrate that DNA methylation participates in the regulation of PAX1 expression directly. Gain- and loss-of-function experiments were used to show that PAX1 overexpression restrained proliferation, migration and improved cisplatin sensitivity by interfering with the WNT/TIMELESS axis in CC cells. Additionally, Co-immunoprecipitation assays further confirmed the interaction between PAX1 and TCF7L2. Taken together, our results suggested that a tumor suppressor role of PAX1 in CC and that CRISPR-based PAX1 demethylation editing might be a promising therapeutic strategy for CC.

Rapid discovery of a novel “green” and natural GST inhibitor for sensitizing hepatocellular carcinoma to Cisplatin by visual screening strategy

Over-expression of glutathione S-transferase (GST) can promote Cisplatin resistance in hepatocellular carcinoma (HCC) treatment. Hence, inhibiting GST is an attractive strategy to improve Cisplatin sensitivity in HCC therapy. Although several synthesized GST inhibitors have been developed, the side effects and narrow spectrum for anticancer seriously limit their clinical application. Considering the abundance of natural compounds with anticancer activity, this study developed a rapid fluorescence technique to screen “green” natural GST inhibitors with high specificity. The fluorescence assay demonstrated that schisanlactone B (hereafter abbreviated as C1) isolated from Xue tong significantly down-regulated GST levels in Cisplatin-resistant HCC cells in vitro and in vivo. Importantly, C1 can selectively kill HCC cells from normal liver cells, effectively improving the therapeutic effect of Cisplatin on HCC mice by down-regulating GST expression. Considering the high GST levels in HCC patients, this compound demonstrated the high potential for sensitizing HCC therapy in clinical practice by down-regulating GST levels.

Senescence-related gene c-Myc affects bladder cancer cell senescence by interacting with HSP90B1 to regulate cisplatin sensitivity.

Patients with advanced bladder cancer gradually become less sensitive to chemotherapeutic agents, leading to tumor recurrence. Initiating the senescence program in solid tumors may be an important means of improving short-term drug sensitivity. The important role of c-Myc in bladder cancer cell senescence was determined using bioinformatics methods. The response to cisplatin chemotherapy in bladder cancer sample was analyzed according to the Genomics of Drug Sensitivity in Cancer database. Cell Counting Kit-8 assay, clone formation assay, and senescence-associated β-galactosidase staining were used to assess bladder cancer cell growth, senescence, and sensitivity to cisplatin, respectively. Western blot and immunoprecipitation were performed to understand the regulation of p21 by c-Myc/HSP90B1. Bioinformatic analysis showed that c-Myc, a cellular senescence gene, was significantly associated with bladder cancer prognosis and sensitivity to cisplatin chemotherapy. c-Myc and HSP90B1 expression were highly correlated in bladder cancer. Reducing the level of c-Myc significantly inhibited bladder cancer cell proliferation, promoted cellular senescence, and enhanced cisplatin chemosensitivity. Immunoprecipitation assays confirmed that HSP90B1 interacted with c-Myc. Western blot analysis showed that reducing the level of HSP90B1 could redeem the p21 overexpression caused by c-Myc overexpression. Further studies showed that reducing HSP90B1 expression could alleviate the rapid growth and accelerate cellular senescence of bladder cancer cells caused by c-Myc overexpression, and that reducing HSP90B1 levels could also improve cisplatin sensitivity in bladder cancer cells. HSP90B1/c-Myc interaction regulates the p21 signaling pathway, which affects cisplatin chemosensitivity by modulating bladder cancer cell senescence.

CUL4A silencing attenuates cervical carcinogenesis and improves Cisplatin sensitivity.

CUL4A is an ubiquitin ligase deregulated in numerous pathologies including cancer and even hijacked by viruses for facilitating their survival and propagation. However, its role in Human papilloma virus (HPV)-mediated cervical carcinogenesis remains elusive. The UALCAN and GEPIA datasets were analyzed to ascertain the transcript levels of CUL4A in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) patients. Subsequently, various biochemical assays were employed to explore the functional contribution of CUL4A in cervical carcinogenesis and to shed some light on its involvement in Cisplatin resistance in cervical cancer. Our UALCAN and GEPIA datasets analyses reveal elevated CUL4A transcript levels in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) patients that correlate with adverse clinicopathological parameters such as tumor stage and lymph node metastasis. Kaplan-Meier plot and GEPIA assessment depict poor prognosis of CESC patients having high CUL4A expression. Varied biochemical assays illustrate that CUL4A inhibition severely curtails hallmark malignant properties such as cellular proliferation, migration, and invasionof cervical cancer cells. We also show that CUL4A knockdown in HeLa cells causes increased susceptibility and better apoptotic induction toward Cisplatin, a mainstay drug used in cervical cancer treatment. More interestingly, we find reversion of Cisplatin-resistant phenotype of HeLa cells and an augmented cytotoxicity towards the platinum compound upon CUL4A downregulation. Taken together, our study underscores CUL4A as a cervical cancer oncogene and illustrates its potential as a prognosis indicator. Our investigation provides a novel avenue in improving current anti-cervical cancer therapy and overcoming the bottle-neck of Cisplatin resistance.

Atorvastatin improves cisplatin sensitivity through modulation of cholesteryl ester homeostasis in breast cancer cells.

Acquired treatment resistance is a significant problem in breast cancer management, and alterations in lipid metabolism have been proposed to contribute to the development of drug resistance as well as other aspects of tumor progression. The present study aimed to identify the role of cholesterol metabolism in MCF-7 and MDA-MB-231 breast cancer cell response to cisplatin (CDDP) treatment in the acute setting and in a model of CDDP resistance. MCF-7 (luminal A), MDA-MB-231 (triple-negative) and CDDP-resistant MDA-MB-231 (MDACR) cell lines were grown in the presence or absence of CDDP in combination with atorvastatin (ATV), lipid depletion or low-density lipoprotein loading and were analyzed by a variety of biochemical and radiometric techniques. Co-administration of CDDP and ATV strongly reduced cell proliferation and viability to a greater extent than CDDP alone, especially in MDA-MB-231 cells. These findings were associated with reduced cholesteryl ester synthesis and storage in MDA-MB-231 cells. In MDACR cells, acetyl-CoA acetyltransferase 1 (ACAT-1) was upregulated compared to naïve MDA-MB-231 cells and ATV treatment restored CDDP sensitivity, suggesting that aberrant ACAT-1 expression and associated changes in cholesterol metabolism contribute to CDDP resistance in MDA-MB-231 cells. These findings indicate that the elevated susceptibility of MDA-MB-231 cells to co-administration of CDDP and ATV, is associated with an increased reliance on cholesteryl ester availability. Our data from these cell culture-based studies identifies altered cholesterol homeostasis as an adaptive response to CDDP treatment that contributes to aggressiveness and chemotherapy resistance.

Targeted OUM1/PTPRZ1 silencing and synergetic CDT/enhanced chemical therapy toward uveal melanoma based on a dual-modal imaging-guided manganese metal–organic framework nanoparticles

Metastasis and chemical resistance are the most serious problems in the treatment of highly aggressive uveal melanoma (UM). The newly identified lncRNA OUM1 is overexpressed in UM, functions as a catalyst and regulates protein tyrosine phosphatase (PTP) activity by binding to PTP receptor type Z1 (PTPRZ1), which plays an important role in cell proliferation, metastasis and chemotherapy resistance in the UM microenvironment. Hence, siRNAs that selectively knocking down the lncRNA OUM1 (siOUM1) and its target gene PTPRZ1 (siPTPRZ1) were designed to inhibit the OUM1/PTPRZ1 pathway to reduce PTP activity, and this reduction in activity interrupts protein tyrosine phosphorylation, suppresses UM proliferation and metastasis and improves cisplatin sensitivity in UM cells. Then, to overcome the limitations of the difficulty of drug administration and traditional therapeutics, the indocyanine green (ICG)-labeled manganese metal–organic framework (MOF) nanoparticles (NPs) were fabricated and linked with arginine-glycine-aspartate (RGD) peptide to carry siOUM1/siPTPRZ1 and cisplatin to achieve targeted siRNA interference-mediated therapy, enhanced cisplatin therapy and chemodynamic therapy. This NP system also has a dual-modal imaging ability because ICG is a near-infrared region fluorescent dye and manganese has the potential to be used in magnetic resonance imaging. This study verifies the significance of the newly discovered lncRNA OUM1 as a new therapeutic target for aggressive UM and provides a drug delivery NP system for precise treatment of UM accompanied with a dual-modal imaging ability.Graphical

Downregulation of ASF1B inhibits tumor progression and enhances efficacy of cisplatin in pancreatic cancer.

Pancreatic cancer is an aggressive and lethal cancer with the highest mortality rate. Hence, the development of new targeting and innovative treatment strategies is needed. Recent studies reported that the histone chaperone anti-silencing function 1B (ASF1B) can be used as a diagnosis and prognosis cancer biomarker. However, functional studies of ASF1B in pancreatic cancer have not been performed. This study compared expression levels of ASF1B in pancreatic cancer specimens with those of normal tissues using publicly available online databases. We found that ASF1B was commonly overexpressed in pancreatic cancer specimens, which is associated with poor prognosis. ASF1B downregulation in pancreatic cancer cells reduced their colony formation, proliferation, migration, and invasion abilities, and inhibited MMP9 activity. Furthermore, ASF1B expression downregulation increased cell cycle S-phase arrest and DNA damage though activation of the checkpoint kinases Chk1 and Chk2 pathways. Additionally, increased caspase (caspases-3 and -9) activation and PARP cleavage led to enhanced caspase-dependent apoptosis and improved cisplatin sensitivity. Collectively, our results indicate that ASF1B may serve as a potential biomarker of pancreatic cancer and a novel therapeutic target.

Interfering lncRNA XIST inhibits the growth of salivary adenoid cystic carcinoma cells and improves cisplatin sensitivity by up-regulating miR-429

Interfering lncRNA XIST inhibits the growth of salivary adenoid cystic carcinoma cells and improves cisplatin sensitivity by up-regulating miR-429

Long non-coding RNA HOXA11-AS knockout inhibits proliferation and overcomes drug resistance in ovarian cancer

ABSTRACT In ovarian carcinogenesis and progression, long non-coding RNAs (lncRNAs) have been shown to have a role, although the underlying processes remain a mystery. By modulating the degree of autophagy in ovarian cancer cells, we sought to learn more about the function lncRNA HOXA11-AS plays in the development of ovarian cancer. The expression of HOXA11-AS in ovarian normal cells and ovarian cancer cell lines was measured using R package and qRT-PCR. Ovarian cancer cells expressed HOXA11-AS substantially higher than normal cells, while cisplatin-resistant cells expressed HOXA11-AS significantly higher than ovarian cancer cells. Next, we studied the prognostic data of HOXA11-AS in ovarian cancer in the Tissue Cancer Genome Atlas (TCGA). In the next step, lentiviral transfection of ovarian cancer cells A2780, OVCAR3, and A2780/DDP (cisplatin-resistant) were performed, and HOXA11-AS knockdown was found to significantly inhibit cell viability, migration, and invasion of A2780 and OVCAR3 cells, and promote apoptosis by CCK-8 assay, transwell assay, cell cycle, and apoptosis assay, and promoted the sensitivity of A2780/DDP cells to cisplatin. It has been shown by the western blot test that HOXA11-AS knockdown increases the amount of cellular autophagy in cells. In contrast, adding the autophagy inhibitor 3-methyladenine (3-MA) to HOXA11-AS cells knocked down in vivo reduced its anti-tumor properties. As a whole, this study found that HOXA11-AS knockdown increased the expression of autophagy-related proteins and improved cisplatin sensitivity, decreased ovarian cancer cell proliferation, and promoted cell apoptosis. This study provides new insights into the role of HOXA11-AS in ovarian cancer regulation.

Aldehyde dehydrogenase 6 family member A1 negatively regulates cell growth and to cisplatin sensitivity in bladder cancer.

Aldehyde dehydrogenase 6 family member A1 (ALDH6A1) is a highly conserved member of aldehyde dehydrogenase (ALDHs) family. Recent studies reveal that it broadly involved in tumorigenesis and drug metabolism in kinds of cancer. However, the critical role of ALDH6A1 in bladder cancer progression and cisplatin resistance of cancer cells are still poorly understood. In this study, we researched the significant function of ALDH6A1 in bladder cancer. Our results showed that ALDH6A1 exhibited a decreased expression in clinical bladder cancer tissues and bladder cancer cell lines. Stable ALDH6A1 knockdown not only could promote cell growth and colony formation in bladder cancer cells, but also enhance drug resistance to cisplatin treatment. On the contrary, we found the active transcript factor hepatocyte nuclear factor 4α (HNF4α, NR2A1) by alveriene could upregulate ALDH6A1 expression, significantly inhibit the cell growth and colony formation of bladder cancer cells, and improve cisplatin sensitivity of bladder cancer cells. Together, our results show that ALDH6A1 plays as a tumor suppressor in bladder cancer, which regulated by HNF4a. ALDH6A1 could be a promising diagnostic marker and treatment target in bladder cancer.

Enhanced antitumor effects of follicle-stimulating hormone receptor-mediated hexokinase-2 depletion on ovarian cancer mediated by a shift in glucose metabolism

BackgroundMost cancers favor glycolytic-based glucose metabolism. Hexokinase-2 (HK2), the first glycolytic rate-limiting enzyme, shows limited expression in normal adult tissues but is overexpressed in many tumor tissues, including ovarian cancer. HK2 has been shown to be correlated with the progression and chemoresistance of ovarian cancer and could be a therapeutic target. However, the systemic toxicity of HK2 inhibitors has limited their clinical use. Since follicle-stimulating hormone (FSH) receptor (FSHR) is overexpressed in ovarian cancer but not in nonovarian healthy tissues, we designed FSHR-mediated nanocarriers for HK2 shRNA delivery to increase tumor specificity and decrease toxicity.ResultsHK2 shRNA was encapsulated in a polyethylene glycol-polyethylenimine copolymer modified with the FSH β 33–53 or retro-inverso FSH β 33–53 peptide. The nanoparticle complex with FSH peptides modification effectively depleted HK2 expression and facilitated a shift towards oxidative glucose metabolism, with evidence of increased oxygen consumption rates, decreased extracellular acidification rates, and decreased extracellular lactate and glucose consumption in A2780 ovarian cancer cells and cisplatin-resistant A2780CP counterpart cells. Consequently, cell proliferation, invasion and migration were significantly inhibited, and tumor growth was suppressed even in cisplatin-resistant ovarian cancer. No obvious systemic toxicity was observed in mice. Moreover, the nanoparticle complex modified with retro-inverso FSH peptides exhibited the strongest antitumor effects and effectively improved cisplatin sensitivity by regulating cisplatin transport proteins and increasing apoptosis through the mitochondrial pathway.ConclusionsThese results established HK2 as an effective therapeutic target even for cisplatin-resistant ovarian cancer and suggested a promising targeted therapeutic approach.

&lt;p&gt;Circ_0110805 Knockdown Enhances Cisplatin Sensitivity and Inhibits Gastric Cancer Progression by miR-299-3p/ENDOPDI Axis&lt;/p&gt;

BackgroundGastric cancer is a prevalent primary stomach tumor. Cisplatin is frequently used to treat gastric cancer. However, the resistance of cisplatin in gastric cancer often occurs, which brings a heavy burden to gastric cancer treatment.MethodsIn this study, we revealed a novel underlying mechanism about cisplatin-resistant effect in gastric cancer. A Cell Counting Kit-8 (CCK-8) cell viability assay and a xenograft model were performed to evaluate the function of circRNA in the cisplatin resistance of gastric cancer.ResultsCompared with control groups, we observed that circ_0110805 was highly expressed, the mRNA and protein expression levels of ENDOPDI were dramatically upregulated, and the expression of miR-299-3p was significantly downregulated in gastric cancer cells, cisplatin-resistant gastric cancer tissues or cells. Functionally, circ_0110805 knockdown improved cisplatin sensitivity, induced cell apoptosis, whereas repressed cell viability, migration and invasion in AGS/DDP and HGC-27/DDP cells, which was reversed by miR-299-3p inhibitor. Additionally, ENDOPDI overexpression hindered the effects of miR-299-3p on cisplatin sensitivity and gastric cancer progression. Circ_0110805 knockdown enhanced cisplatin sensitivity in vivo. Mechanistically, circ_0110805 acted as a sponge of miR-299-3p and its targeted ENDOPDI.ConclusionWe showed that circ_0110805 knockdown increased the sensitivity of gastric cancer to cisplatin, which also repressed gastric cancer progression by sponging miR-299-3p to downregulate ENDOPDI expression. It might provide a new insight for future studying cisplatin-resistant gastric cancer.

A Non-genetic Mechanism Involving the Integrin β4/Paxillin Axis Contributes to Chemoresistance in Lung Cancer.

SummaryTumor heterogeneity and cisplatin resistance are major causes of tumor relapse and poor survival. Here, we show that in lung cancer, interaction between paxillin (PXN) and integrin β4 (ITGB4), components of the focal adhesion (FA) complex, contributes to cisplatin resistance. Knocking down PXN and ITGB4 attenuated cell growth and improved cisplatin sensitivity, both in 2D and 3D cultures. PXN and ITGB4 independently regulated expression of several genes. In addition, they also regulated expression of common genes including USP1 and VDAC1, which are required for maintaining genomic stability and mitochondrial function, respectively. Mathematical modeling suggested that bistability could lead to stochastic phenotypic switching between cisplatin-sensitive and resistant states in these cells. Consistently, purified subpopulations of sensitive and resistant cells re-created the mixed parental population when cultured separately. Altogether, these data point to an unexpected role of the FA complex in cisplatin resistance and highlight a novel non-genetic mechanism.

Stimuli-responsive combination therapy of cisplatin and Nrf2 siRNA for improving antitumor treatment of osteosarcoma

Cisplatin is a widely applied therapeutics for the treatment of osteosarcoma. However, its clinical applications have been hindered due to low efficacy and bioavailability, and particularly frequent emergence of reactive oxygen species (ROS)-decrease induced drug resistance. The transcription factor NF-E2-related factor 2 (Nrf2) is increased in cancer patients and induces poor outcome in osteosarcoma treatment, making it a novel target to improve the efficacy of chemotherapy. Herein, a hyaluronidase-responsive multi-layer liposome (HLCN) for co-delivery of cisplatin and Nrf2 siRNA (siNrf2) is developed. It is composed of Vpr52-96 modified liposome covered with hyaluronic acid (HA). HLCN selectively accumulates in osteosarcoma by targeting tumor-specific CD44, and can be degraded by endosomal hyaluronidase to generate cationic liposome, which promotes the endosomal escape of Vpr52-96, cisplatin and siNrf2. HLCN can effectively decrease Nrf2 level, promote ROS generation, activate itochondrial apoptotic pathway, and consequently enhance anticancer efficacy of cisplatin. Particularly, HLCN shows high cytotoxicity to osteosarcoma cells with an IC50 value of about 1 µM, which is four-fold lower than liposomal cisplatin (IC50 4 µM), indicating that Nrf2 silence can significantly improve cisplatin sensitivity in cancer cells. Importantly, HLCN can remarkably inhibit tumor growth in the xenograft osteosarcoma mice with minimal systemic adverse effects. Therefore, this novel stimuli-responsive combination therapy of cisplatin and siNrf2 provides a promising strategy for the treatment of osteosarcoma.

Although c‑MYC contributes to tamoxifen resistance, it improves cisplatin sensitivity in ER‑positive breast cancer.

Tamoxifen (TAM) resistance is a major challenge in the treatment of estrogen receptor-positive (ER+) breast cancer. To date, to the best of our knowledge, there are only a few studies available examining the response of patients with TAM-resistant breast cancer to chemotherapy, and the guidelines do not specify recommended drugs for these patients. In the present study, TAM-resistant cells were shown to exhibit increased proliferation and invasion compared with the parent cells, and the increased expression of c-MYC was demonstrated to play an important role in TAM resistance. Furthermore, the TAM-resistant cells were significantly more sensitive to cisplatin compared with the parent cells, and the silencing of c-MYC expression desensitized the cells to cisplatin through the inhibition of the cell cycle. An increased c-MYC expression was observed in 28 pairs of primary and metastatic tumors from patients treated with TAM, and the clinical remission rate of cisplatin-based chemotherapy was significantly higher compared with other chemotherapy-based regimens in 122 patients with TAM resistant breast cancer. Taken together, the data of the present study demonstrated that although c-MYC was involved in TAM resistance, it increased the sensitivity of ER+ breast cancer to cisplatin. Thus, cisplatin may be a preferred chemotherapeutic agent for the treatment of patients with TAM-resistant breast cancer, particularly in patients where the rapid control of disease progression is required.

HOXB7 mediates cisplatin resistance in esophageal squamous cell carcinoma through involvement of DNA damage repair.

BackgroundDNA damage repair is an important mechanism of platinum resistance. HOXB7 is one member of HOX family genes, which are essential developmental regulators and frequently dysregulated in cancer. Recently, its relevance in chemotherapy resistance and DNA damage repair has also been addressed. However, little is known regarding the association between HOXB7 and chemotherapy resistance in esophageal squamous cell carcinoma (ESCC).MethodsThe association between HOXB7 expression detected by immunohistochemisty and tumor regression grade (TRG) and long‐term survival was analyzed in 143 ESCC patients who underwent neoadjuvant chemotherapy. CCK8 assay was used to examine the effect of cisplatin in a panel of four ESCC cell lines. A stable cell strain with HOXB7 knockdown of KYSE150 and KYSE450 was established to explore the effect on cisplatin sensitivity. The interaction of HOXB7 with Ku70, Ku80 and DNA‐PKcs was determined by GST‐pull down, coimmunoprecipitation and immunofluorescent colocalization. Finally, we investigated whether disrupting HOXB7 function by a synthetic peptide HXR9 blocking the formation of HOXB7/PBX could enhance cisplatin sensitivity in vitro and in vivo.ResultsHigh expression of HOXB7 was associated with cisplatin resistance and worse chemotherapy efficacy. HOXB7 knockdown reinforced cisplatin sensitivity. It was identified that HOXB7 interacts with Ku70, Ku80 and DNA‐PKcs. HOXB7 knockdown was related to the downregulation of Ku70, Ku80 and DNA‐PKcs as well as arrested cell cycle in S phase. HOXB7 inhibition by HXR9 had a synergistic effect to improve cisplatin sensitivity.ConclusionHOXB7 may be a biomarker for the prediction of chemoresistance of ESCC and serves as a promising therapeutic target.

MicroRNA-152 suppresses cisplatin resistance in A549 cells.

The present study aimed to investigate the association between microRNA-152 and cisplatin resistance in non-small cell lung cancer. A549 and cisplatin-resistant A549 cells (A549/cis) were maintained in vitro. Reverse transcription-quantitative PCR (RT-qPCR) was performed to analyze differences in microRNA-152 levels between A549 and A549/cis cells, and changes in Bcl-2 and NF-κB expression levels were analyzed via RT-qPCR and western blot analyses. MicroRNA-152 was overexpressed in A549/cis cells via transfection of a microRNA-152 mimic. Upon treating transfected or untransfected A549/cis cells with 2 µg/l cisplatin for 24 h, a Cell Counting Kit-8 assay, morphological analysis and flow cytometry analysis were performed to evaluate the effect of microRNA-152 on the inhibition of cell proliferation and induction of apoptosis. Furthermore, changes in Bcl-2 and NF-κB expression levels in microRNA-152-overexpressing A549/cis cells were also analyzed. MicroRNA-152 was significantly downregulated and Bcl-2 and NF-κB were significantly upregulated in A549/cis cells (P<0.05). MicroRNA-152 upregulation enhanced the inhibitory effect of cisplatin on A549/cis cells. These results suggest that microRNA-152 downregulates Bcl-2 and NF-κB. MicroRNA-152 downregulation may induce cisplatin resistance in non-small cell lung cancer cells, whereas microRNA-152 upregulation may improve cisplatin sensitivity among A549/cis cells via downregulation of Bcl-2 and NF-κB.

TNFAIP8 promotes cisplatin resistance in cervical carcinoma cells by inhibiting cellular apoptosis.

Cervical cancer is the second most prevalent malignant tumor in women worldwide. Failure of successful treatment is most prevalent in patients with the metastatic disease and the chemotherapy refractory disease. Tumor necrosis factor α-induced protein 8 (TNFAIP8) serves as an anti-apoptotic and pro-oncogenic protein, and is associated with cancer progression and poor prognosis in a number of different cancer types. However, the physiological and pathophysiological roles of TNFAIP8 in cervical carcinogenesis and development remain poorly understood. In the present study, it was demonstrated that TNFAIP8 protein expression levels were significantly increased in cervical cancer tissues compared with the non-tumor adjacent tissues using immunohistochemistry. Additionally, it was demonstrated that TNFAIP8 overexpression is associated with cisplatin resistance. Furthermore, depletion of TNFAIP8 impaired HeLa cell proliferation and viability in vitro, improved cisplatin sensitivity, and promoted cisplatin-induced cellular apoptosis and death. Subsequent mechanistic analysis demonstrated that TNFAIP8 silencing promoted caspase-8/-3 activation and p38 phosphorylation in HeLa cells treated with cisplatin, whereas apoptosis regulator B-cell lymphoma-2 expression was inhibited with TNFAIP8-silenced HeLa cells following treatment with cisplatin. These data suggested that TNFAIP8 serves as an anti-apoptotic protein against cisplatin-induced cell death, which eventually leads to chemotherapeutic drug-treatment failure. Therefore, the present data suggested that TNFAIP8 may be a promising therapeutic target for the treatment of cervical cancer.

Letrozole improves the sensitivity of breast cancer cells overexpressing aromatase to cisplatin via down-regulation of FEN1

PurposeFlap endonuclease 1 (FEN1) is up-regulated by estrogen (17β-estradiol, E2) and related to cisplatin resistance of human breast cancer cells. Letrozole, an aromatase inhibitor, suppresses the change of testosterone into estrogen and is frequently used to treat breast cancer. However, the effects of letrozole on FEN1 expression and cisplatin sensitivity in breast cancer cells overexpressing aromatase have not been revealed.MethodsThe expression of FEN1 and the proteins in ERK/Elk-1 signaling were evaluated by RT-PCR and Western blot. Cisplatin sensitivity was explored through CCK-8 and flow cytometry analysis, respectively. FEN1 siRNAs and FEN1 expression plasmid were transfected into cells to down-regulate or up-regulate FEN1 expression. The promotor activity of FEN1 was detected using luciferase reporter assay.ResultsFEN1 down-regulation improved cisplatin sensitivity of breast cancer cells overexpressing aromatase. Letrozole down-regulated FEN1 expression and increased cisplatin sensitivity. The sensitizing effect of letrozole to cisplatin was dependent on FEN1 down-regulation. FEN1 overexpression could block the sensitizing effect of letrozole to cisplatin. Testosterone up-regulated the promotor activity, protein expression of FEN1, and phosphorylation of ERK/Elk-1, which could be eliminated by both letrozole and MEK1/2 inhibitor U0126. Letrozole down-regulated FEN1 expression in an ERK/Elk-1-dependent manner.ConclusionsOur findings clearly demonstrate that letrozole improves cisplatin sensitivity of breast cancer cells overexpressing aromatase via down-regulation of FEN1 and suggest that a combined use of letrozole and cisplatin may be a potential treatment protocol for relieving cisplatin resistance in human breast cancer.

Self-targeted knockdown of CD44 improves cisplatin sensitivity of chemoresistant non-small cell lung cancer cells.

Chemoresistance remains a major challenge for effective chemotherapy of non-small-cell lung carcinoma (NSCLC). CD44 expression is related to the susceptibility of various cancer cell types to anticancer drugs. Here, we systematically investigated the CD44-dependent chemoresistance of NSCLC cells and developed a liposomal siRNA delivery system to overcome this chemoresistance by the self-targeted downregulation of CD44. We confirmed the relationship between the expression of CD44 and the chemosensitivity of NSCLC cells using flow cytometry and MTT assay. We then generated and characterized cisplatin-resistant cell lines and compared the expression of CD44 in resistant cells to that in parental cells using western blotting. To evaluate whether the chemosensitivity of resistant cells depends on CD44 expression, we performed CD44 knockdown using CD44 siRNA and detected the chemosensitivity of these cells. Additionally, we prepared hyaluronic acid (HA)-coated liposomes as a targeted delivery system to selectively deliver CD44-specific siRNA to chemoresistant NSCLC cells and observed whether the chemosensitivity of these cells was improved. We found that CD44 expression is inversely proportional to the degree of cellular response to cisplatin chemotherapy and that CD44 is overexpressed in chemoresistant NSCLC cells. By performing CD44 knockdown using siRNA, we reconfirmed that the chemosensitivity of resistant cells depends on CD44 expression. We also observed that HA-liposome-mediated siRNA delivery prior to cisplatin chemotherapy significantly reduced CD44 expression and enhanced cisplatin sensitivity in chemoresistant NSCLC cells. These results suggest that self-targeted downregulation of chemoresistance-associated cell surface proteins during chemotherapy is an effective therapeutic strategy for overcoming the chemoresistance of NSCLC cells.