Up-regulation of Bfl-1/A1 via NF-κB activation in cisplatin-resistant human bladder cancer cell line

CAB39 promotes cisplatin resistance in bladder cancer via the LKB1-AMPK-LC3 pathway

Systemic therapy for muscle-invasive bladder cancer (BC) remains dominated by cisplatin-based chemotherapy. However, resistance to cisplatin therapy greatly limits long-term survival. Resistance to cisplatin-based chemotherapy still needs to be addressed. In this study, we established three cisplatin-resistant BC cell lines by multiple cisplatin pulse treatments. Interestingly, after exposure to cisplatin, all cisplatin-resistant cell lines showed lower reactive oxygen species (ROS) levels than the corresponding parental cell lines. Using proteomic analysis, we identified 35 proteins that were upregulated in cisplatin-resistant BC cells. By knocking down eleven of these genes, we found that after CAB39 knockdown, BC cisplatin-resistant cells were more sensitive to cisplatin. Overexpression of CAB39 had the opposite effect. Then, the knockdown of six genes downstream of CAB39 revealed that CAB39 promoted cisplatin resistance in BC through LKB1. Moreover, a key cause of cisplatin-induced cell death is damage to mitochondria and increased ROS levels. In our study, cisplatin-resistant cells exhibited higher autophagic flux and healthier mitochondrial status after cisplatin exposure. We demonstrated that the CAB39-LKB1-AMPK-LC3 pathway plays a critical role in enhancing autophagy to maintain the health of mitochondria and reduce ROS levels. In addition, the autophagy inhibitor chloroquine (CQ) can significantly enhance the killing effect of cisplatin on BC cells. Compared with gemcitabine plus cisplatin (GC), GC plus CQ significantly reduced tumor burden in vivo. In conclusion, our study shows that CAB39 counteracts the killing of cisplatin by enhancing the autophagy of BC cells to damaged mitochondria and other organelles to alleviate the damage of cells caused by harmful substances such as ROS.

TFAP2C Knockdown Sensitizes Bladder Cancer Cells to Cisplatin Treatment via Regulation of EGFR and NF-κB

Simple Summary

Bladder cancer (BCa) is considered one of the most common neoplasms of the urology system. Cisplatin-based chemotherapy has been the primary treatment for patients with advanced or metastatic BCa. Nevertheless, cisplatin resistance often limits the treatment of bladder cancer. We expect to find approaches to improve the therapeutic efficacy of cisplatin in bladder cancer. In recent years, many studies have shown that transcription factor AP-2 gamma (TFAP2C) acts as a key player in cancer development and and its expression level is closely related to the sensitivity of tumors to cisplatin. Our study investigated whether TFAP2C affects the sensitivity of BCa cells to cisplatin and the possible mechanisms. We found that TFAP2C expression was significantly upregulated in most BCa tissues compared to adjacent normal tissues. The present study confirmed that TFAP2C knockdown enhanced the anti-tumor effects of cisplatin by decreasing cisplatin-induced activation levels of epidermal growth factor receptor (EGFR) and nuclear factor kappaB (NF-κB). Specifically, this study provides a novel approach to improve the efficacy of cisplatin.

Abstract

Cisplatin is the first-line chemotherapy for advanced or metastatic bladder cancer. Nevertheless, approximately half of patients with BCa are insensitive to cisplatin therapy or develop cisplatin resistance during the treatment process. Therefore, it is especially crucial to investigate ways to enhance the sensitivity of tumor cells to cisplatin. Transcription factor AP-2 gamma (TFAP2C) is involved in cancer development and chemotherapy sensitivity. However, its relationship with chemotherapy has not been studied in BCa. In this study, we aimed to investigate the therapeutic potential of TFAP2C in human BCa. Results based on TCGA (The Cancer Genome Atlas), GTEx (The Genotype-Tissue Expression) and GEO (Gene Expression Omnibus) data showed that TFAP2C expression was upregulated in BCa tissues and that its high expression was associated with poor prognosis. Meanwhile, we demonstrated the overexpression of TFAP2C in BCa clinical specimens. Subsequently, in vitro, we knocked down TFAP2C in BCa cells and found that TFAP2C knockdown further increased cell cycle arrest and apoptosis caused by cisplatin. In addition, the inhibitory effect of cisplatin on BCa cell migration and invasion was enhanced by TFAP2C knockdown. Our data indicated that cisplatin increased epidermal growth factor receptor (EGFR) and nuclear factor-kappaB (NF-κB) activation levels, but TFAP2C knockdown suppressed this effect. Finally, in vivo data further validated these findings. Our study showed that TFAP2C knockdown affected the activation levels of EGFR and NF-κB and enhanced the anti-tumor effects of cisplatin in vivo and in vitro. This provides a new direction to improve the efficacy of traditional cisplatin chemotherapy.

Evaluation of nuclear NF-κB, transglutaminase2, and ERCC1 as predictors of platinum resistance in testicular tumors

PURPOSE

Testicular germ cells tumor (TGCT) are associated with a high cure rate and are treated with platinum-based chemotherapy. However, a group of testicular cancer patients may have a very unfavorable evolution and insensitivity to the main therapeutic agent chemotherapy (CT) cisplatin. The aim of this study was to evaluate the risk of recurrence and overall survival related to the expression of nuclear factor kappa-B (NF-κB), transglutaminase 2 (TG2) and excision repair cross-complementation group 1 (ERCC1) in patients with TGCT treated with platinum combinations.

PATIENTS AND METHODS

A retrospective study was performed with TGCT patients treated with platinum-based chemotherapy. Immunohistochemical analysis was performed and the expression was correlated with clinical and laboratory data.

RESULTS

Fifty patients were included, the mean age was 28.4 years (18 to 45), and 76% were non-seminoma. All patients were treated with standard cisplatin, etoposide and bleomycin or cisplatin, and etoposide. Patient's analyzed immunodetection for NF-κB, TG2, and ERCC1 were positive in 76%, 54% and 42%, respectively. Multivariate analysis identified that positive expressions to ERCC1 and NF-κB are independent risk factors for higher recurrence TGCT after chemotherapy (RR 2.96 and 3.16, respectively). Patients with positive expression of ERCC1 presented a poor overall survival rate for 10-year follow (p=0.001).

CONCLUSIONS

The expression of ERCC1 and NF-κB give a worse prognosis for relapse, and only ERCC1 had an influence on the overall survival of TGCT patients treated with platinum-based chemotherapy. These may represent markers that predict poor clinical outcome and response to cisplatin.

Prenylated Rab acceptor RABAC1 inhibits anti-apoptotic protein BCL2A1 and induces apoptosis

The B cell lymphoma 2 (BCL2) family of proteins constitutes a critical intracellular checkpoint in the intrinsic apoptosis pathway. Among BCL2 members, the anti-apoptotic protein BCL2A1 mediates the resistance to BCL2 inhibitors and may be considered as a target for anti-cancer therapy. Here, we report that prenylated Rab acceptor 1 (RABAC1 or PRA1) inhibits the anti-apoptotic activity of BCL2A1 and induces apoptosis in AGS gastric cancer cells. Protein interaction of BCL2A1 and RABAC1 was verified by an in-vitro glutathione-S-transferase pull-down assay, immunoprecipitation, and confocal microscopy. When apoptosis was induced by cisplatin, the anti-apoptotic activity of BCL2A1 was blocked by RABAC1 expression. RABAC1 caused caspase-3 activation and decreased cell proliferation, clonogenic cell survival, and cell migration and invasion. We suggest RABAC1 as a potential therapeutic target for BCL2A1-related cancer.

The inhibitory effect of polysaccharide from Rhizopus nigricans on colitis-associated colorectal cancer

An extracellular polysaccharide (EPS1-1) of Rhizopus nigricans was found to enhance immunity and reduce colon cancer cell proliferation. Here, the effect of EPS1-1 on a mouse model of colitis-associated cancer (CAC) induced by azoxymethane (AOM)/dextran sodium sulfate (DSS) was investigated. Pathological symptoms, including weight loss, piloerection, hematochezia and insensitivity caused by AOM/DSS, were relieved by EPS1-1. Anatomical results showed a 100% tumor incidence, a series of neoplasms, disordered cell structure and hyperplastic glands in the model group, while the abnormal behaviors were relieved and the tumors decreased in the EPS1-1 group. Compared with the model group, the EPS1-1 group showed decreased oncogenic protein (COX-2, β-catenin, CyclinD1 and C-Myc) expression. TUNEL staining showed that EPS1-1 increased the apoptosis of colon cancer cells in mice. Furthermore, the expression of proliferative proteins (Ki-67 and PCNA) and an antiapoptotic gene transcript (Bcl-2) were significantly down regulated by EPS1-1, while apoptotic gene transcripts (p53 and Bax) were enhanced. In addition, EPS1-1 notably decreased the number of cells positive for CD68, F4/80 and NF-κB and reduced the concentrations of inflammatory factors (TNF-α and IL-6) in serum compared with those in the model group. Taken together, these results suggest that EPS1-1 may be a therapeutic option for the prevention and treatment of CAC.

ZBTB7 evokes 5-fluorouracil resistance in colorectal cancer through the NF‑κB signaling pathway

Zinc finger and BTB domain containing 7A (ZBTB7), a POZ/BTB and Krüppel erythroid myeloid oncogenic factor, is critical for the tumorigenicity and progression of various cancer types. ZBTB7 has been reported to promote the cell proliferation of colorectal cancers (CRC). However, the function of ZBTB7 to 5-fluorouracil (5‑FU) resistance has not yet been studied. In the current study, ZBTB7 expression and function in 5‑FU resistance in CRC were investigated using with multidisciplinary approaches, including western blot analysis, Transwell assay, CCK8 and a tumor xenograft model. Overexpression of ZBTB7 was increased the level of proteins associated with cell invasion and epithelial-mesenchymal transition. ZBTB7 inhibition attenuated the invasion and enhanced the apoptosis of CRC cells. IC50 values and cell viability were significantly reduced in cells with short hairpin RNA (shRNA)-mediated ZBTB7 depletion compared with the control group. 5‑FU administration decreased viability to a greater extent in the ZBTB7-shRNA group compared with the control, which was dose- and time-dependent. Analysis of gene expression omnibus data demonstrated that ZBTB7 mediated 5‑FU resistance, potentially through nuclear factor (NF)-κB signaling. NF‑κB inhibitor SN50 reversed ZBTB7-induced resistance in CRC. Collectively, the findings demonstrated that ZBTB7 mediated 5‑FU resistance in CRC cells through NF‑κB signaling. Thus, targeting ZBTB7 and NF‑κB signaling may be an effective strategy to reverse 5‑FU resistance in CRC.

Rab11 Functions as an Oncoprotein via Nuclear Factor kappa B (NF-κB) Signaling Pathway in Human Bladder Carcinoma

Background

Elevated expression of Rab11 has been reported in different human cancers, including human bladder carcinoma. This study, we investigated the biological effects and mechanism of Rab11 overexpression in human bladder carcinoma for the first time.

Material/Methods

Rab11 expression in bladder cancer tissues was detected using immunohistochemistry and Western blot analysis. Then, Rab11 expression was inhibited in T24 cells and it was overexpressed in BIU-87 cells. The effects of Rab11 perturbations on cell growth rate and invasion were analyzed by CCK8, cell cycle assay, and matrix gel invasion assay. MMP-9, cyclin E, and cyclin D1 levels were studied using Western blot and qPCR. NF-κB activity was studied by luciferase assay.

Results

High expression of Rab11 was detected in 41.5% (66/159) of tumor specimens. We found a significant correlation between high Rab11 expression and depth of tumor invasion (P=0.004). Rab11 overexpression was observed to promote the growth rate and invasiveness of cancer cells through upregulation of MMP9, cyclin E, and cyclin D1 levels. Rab11 overexpression further elevated NF-κB reporter activity and enhanced p-IκB expression. Use of BAY 11-7082, a noted NF-κB inhibitor, partially abolished overexpression of MMP9 and cyclin D1 by Rab11.

Conclusions

Our research proved that high Rab11 expression enhances cellular multiplication and invasiveness of bladder cancer, possibly by regulating the NF-κB signaling pathway.

Androgen receptor activity modulates responses to cisplatin treatment in bladder cancer

Cisplatin (CDDP)-based combination chemotherapy remains the mainstream treatment for advanced bladder cancer. However, its efficacy is often limited due to the development of resistance for which underlying mechanisms are poorly understood. Meanwhile, emerging evidence has indicated the involvement of androgen-mediated androgen receptor (AR) signals in bladder cancer progression. In this study, we aimed to investigate whether AR signals have an impact on sensitivity to CDDP in bladder cancer cells. UMUC3-control-short hairpin RNA (shRNA) cells with endogenous AR and AR-negative 647V/5637 cells stably expressing AR were significantly more resistant to CDDP treatment at its pharmacological concentrations, compared with UMUC3-AR-shRNA and 647V-vector/5637-vector control cells, respectively. A synthetic androgen R1881 significantly reduced CDDP sensitivity in UMUC3, 647V-AR, or 5637-AR cells, and the addition of an anti-androgen hydroxyflutamide inhibited the effect of R1881. In these AR-positive cells, R1881 treatment also induced the expression levels of NF-κB, which is known to involve CDDP resistance, and its phosphorylated form, as well as nuclear translocation of NF-κB. In CDDP-resistant bladder cancer sublines established following long-term culture with CDDP, the expression levels of AR as well as NF-κB and phospho-NF-κB were considerably elevated, compared with respective control sublines. In bladder cancer specimens, there was a strong trend to correlate between AR positivity and chemoresistance. These results suggest that AR activation correlates with CDDP resistance presumably via modulating NF-κB activity in bladder cancer cells. Targeting AR during chemotherapy may thus be a useful strategy to overcome CDDP resistance in patients with AR-positive bladder cancer.

Current FDA-approved treatments for non-small cell lung cancer and potential biomarkers for its detection

BACKGROUND

Lung cancer is the leading worldwide cancer with almost 1.5 million deaths every year. Some drugs for lung cancer treatment have been available on the market for decades, but novel drugs have emerged promising better outcomes, especially for Non-Small Cell Lung Cancer (NSCLC), which represents 75% of lung cancer cases. However, how much do drugs have evolved for NSCLC treatment? Are they sharing the same mechanism of action?

AIM

In this review we analyzed how the approved drugs by Federal Drug Agency for NSCLC have advanced in the last four decades identifying shared mechanism of action of medicines against NSCLC treatment and some of the potential biomarkers for early detection.

RESULTS

Cisplatin and its derivatives are still the most used therapy in combination with some other more specific drugs. However, increasing the survival rates seems to be a great challenge and research is moving into early detection through biomarkers but also trying to identify molecules such as those derived from the immune system, cell-free DNA, non-coding RNAs, but also polymorphisms to detect early tumor formation.

CONCLUSIONS

Cisplatin and derivatives have been one of the most successful therapies in spite of their side effects and low specificity. Some of the drugs developed after cisplatin discovery, have been targeted the epidermal growth factor receptor, anaplastic lymphoma kinase, programmed cell death 1 ligand and vascular endothelial growth factor. Since none of the pharmacological treatments in combination with radiation/surgery have extended dramatically the survival rate, research is now focused in early cancer detection in combination with precision medicine, which attempts to treat patients individually according to their stage and tumor characteristics.

TRIM29 Overexpression Promotes Proliferation and Survival of Bladder Cancer Cells through NF-κB Signaling

Purpose

TRIM29 overexpression has been reported in several human malignancies and showed correlation with cancer cell malignancy. The aim of the current study is to examine its clinical significance and biological roles in human bladder cancer tissues and cell lines.

Materials and Methods

A total of 102 cases of bladder cancer tissues were examined for TRIM29 expression by immunohistochemistry. siRNA and plasmid transfection were performed in 5637 and BIU-87 cell lines. Cell Counting Kit-8, flow cytometry, western blot, and real-time polymerase chain reaction were performed to examine its biological roles and mechanism in bladder cancer cells.

Results

We found that TRIM29 overexpression showed correlation with invading depth (p=0.0087). Knockdown of TRIM29 expression in bladder cancer cell line 5637 inhibited cell growth rate and cell cycle transition while its overexpression in BIU-87 cells accelerated cell proliferation and cell cycle progression. TRIM29 overexpression also inhibited cell apoptosis induced by cisplatin. In addition, we demonstrated that TRIM29 depletion decreased while its overexpression led to upregulated expression of cyclin D1, cyclin E, and Bcl-2. We also showed that TRIM29 knockdown inhibited protein kinase C (PKC) and nuclear factor κB (NF-κB) signaling while its overexpression stimulated the PKC and NF-κB pathways. BAY 11-7082 (NF-κB inhibitor) partly attenuated the effect of TRIM29 on expression of cyclin and Bcl-2. Treatment with PKC inhibitor staurosporine resulted in ameliorated TRIM29 induced activation of NF-κB.

Conclusion

The current study demonstrated that TRIM29 upregulates cyclin and Bcl family proteins level to facilitate malignant cell growth and inhibit drug-induced apoptosis in bladder cancer, possibly through PKC–NF-κB signaling pathways.

Upregulated expression of BCL2, MCM7, and CCNE1 indicate cisplatin-resistance in the set of two human bladder cancer cell lines: T24 cisplatin sensitive and T24R2 cisplatin resistant bladder cancer cell lines

Purpose

The mechanism of resistance to cisplatin during treatment of bladder cancer (BC) has been a subject of intense investigation in clinical research. This study aims to identify candidate genes associated with resistance to cisplatin, in order to understand the resistance mechanism of BC cells to the drug, by combining the use of microarray profiling, quantitative reverse transcription-polymerase chain reaction (RT-PCR), and Western blot analyses.

Materials and Methods

The cisplatin sensitive human BC cell line (T24) and the cisplatin resistant BC cell line, T24R2, were used for microarray analysis to determine the differential expression of genes that are significant in cisplatin resistance. Candidate upregulated genes belonging to three well-known cancer-related KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways (p53 tumor suppressor, apoptosis, and cell cycle) were selected from the microarray data. These candidate genes, differentially expressed in T24 and T24R2, were then confirmed by quantitative RT-PCR and western blot. A fold change ≥2 with a p-value <0.05 was considered significant.

Results

A total of 18 significantly upregulated genes were detected in the three selected cancer-related pathways in both microarray and RT-PCR analyses. These genes were PRKAR2A, PRKAR2B, CYCS, BCL2, BIRC3, DFFB, CASP6, CDK6, CCNE1, STEAP3, MCM7, ORC2, ORC5, ANAPC1, and ANAPC7, CDC7, CDC27, and SKP1. Western blot analyses also confirmed the upregulation of BCL2, MCM7, and CCNE1 at the protein level, indicating their crucial association with cisplatin resistance.

Conclusions

The BCL2, MCM7, and CCNE1 genes might play distinctive roles in cisplatin resistance in BC.

Rab23 is overexpressed in human bladder cancer and promotes cancer cell proliferation and invasion

Rab23 overexpression has been implicated in several human cancers. However, its expression pattern and biological roles in human bladder cancer have not been elucidated. In this study, we examined Rab23 expression in 93 bladder cancer specimens and analyzed its correlation with clinicopathological parameters. We found that Rab23 was overexpressed in 45 of 93 (48.3 %) cancer specimens. Significant association was found between Rab23 overexpression and tumor invasion depth (p = 0.0027). Rab23 overexpression also negatively correlated with FGFR3 protein expression (p = 0.021). We found that Rab23 expression was lower in normal bladder transitional cell line SV-HUC-1 than in bladder cancer cell lines BIU-87, 5637, and T24. We knocked down Rab23 expression in T24 cancer cells and transfected a Rab23 plasmid in the BIU-87 cell line. Rab23 depletion inhibited cell growth rate and invasion, while its overexpression resulted in increased cell growth and invasion. In addition, we demonstrated that Rab23 depletion decreased and its transfection upregulated expression of cyclin E, c-myc, and MMP-9. Furthermore, we showed that Rab23 knockdown inhibited NF-κB signaling and its overexpression upregulated NF-κB signaling. BAY 11-7082 (NF-κB inhibitor) partly inhibited the effect of Rab23 on cyclin E and MMP-9 expression. In conclusion, the present study demonstrated that Rab23 overexpression facilitates malignant cell growth and invasion in bladder cancer through the NF-κB pathway.

Role of the pro-survival molecule Bfl-1 in melanoma

Bfl-1 is a pro-survival Bcl-2 family member overexpressed in a subset of chemoresistant tumours, including melanoma. Here, we characterised the expression and regulation of Bfl-1 in normal and malignant melanocytes and determined its role in protecting these cells from chemotherapy-induced apoptosis. Bfl-1 was mitochondrially resident in both resting and apoptotic cells and experienced regulation by the proteasome and NFκB pathways. siRNA-mediated knockdown enhanced sensitivity towards various relevant drug treatments, with forced overexpression of Bfl-1 protective. These findings identify Bfl-1 as a contributor towards therapeutic resistance in melanoma cells and support the use of NFκB inhibitors alongside current treatment strategies.

Cisplatin inhibits hippocampal cell proliferation and alters the expression of apoptotic genes

The hippocampus, which is critical for memory and spatial navigation, contains a proliferating stem cell niche that is especially vulnerable to antineoplastic drugs such as cisplatin. Although the damaging effects of cisplatin have recently been recognized, the molecular mechanisms underlying its toxic effects on this vital region are largely unknown. Using a focused apoptosis gene array, we analyzed the early cisplatin-induced changes in gene expression in the hippocampus of adult Sprague-Dawley rats and compared the results to those from the inferior colliculus, a non-mitotic auditory region resistant to cisplatin-induced cell death. Two days after a 12 mg/kg dose of cisplatin, significant increases were observed in five proapoptotic genes: Bik, Bid, Bok, Trp53p2, and Card6 and a significant decrease in one antiapoptotic gene Bcl2a1. In contrast, Nol3, an antiapoptotic gene, showed a significant increase in expression. The cisplatin-induced increase in Bid mRNA and decrease in Bcl2a1 mRNA were accompanied by a corresponding increase and decrease of their respective proteins in the hippocampus. In contrast, the cisplatin-induced changes in Bcl2a1, Bid, Bik, and Bok gene expression in the inferior colliculus were strikingly different from those in the hippocampus consistent with the greater susceptibility of the hippocampus to cisplatin toxicity. Cisplatin also significantly reduced immunolabeling of the cell proliferation marker Ki67 in the subgranular zone of the hippocampus 2 days post-treatment. These results indicate that cisplatin-induced hippocampal cell death is mediated by increased expression of proapoptotic and decreased antiapoptotic genes and proteins that likely inhibit hippocampal cell proliferation.

18α-glycyrrhetinic acid extracted from Glycyrrhiza radix inhibits proliferation and promotes apoptosis of the hepatic stellate cell line

OBJECTIVE

To evaluate the effect of 18α-glycyrrhetinic acid (18α-GA) on the proliferation and apoptosis of hepatic stellate cells (HSCs) and its underlying mechanisms.

METHODS

HSCs (both human and rat HSCs) were pretreated with or without selective peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist, GW9662, before 18a-GA treatment. Cell cycle and apoptosis of HSCs were analyzed by flow cytometry, and changes in cell cycle and apoptosis-related proteins were analyzed by Western blot. The effect of 18α-GA on nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) DNA-binding activity was measured by ArrayStar transcription factor activity assay.

RESULTS

18α-GA markedly reduced LX-2 cell numbers by 14.8% and 31.2% after 48 h and 72 h of treatment, respectively (P < 0.05). 18α-GA also significantly increased the percentage of LX-2 cells in phase G0/G1 and decreased it in phase S after treated for 48 h and 72 h compared with the control group. 18α-GA increased apoptosis to 6.8% at 48 h, compared with control (2.5%), and at 72 h the percentages of apoptotic cells in control and the treatment groups were 3.1% and 15.6%, respectively, in LX-2 cells (P < 0.01). Similar changes occurred in CCl₄-cirrhotic fat-storing cells. Furthermore, 18α-GA induced expression of PPAR-γ and altered some cell cycle and apoptosis-related proteins. 18α-GA also inhibited NF-κB DNA-binding activity. All these effects were abolished by GW9662.

CONCLUSIONS

18α-GA inhibits the proliferation of activated HSCs and induces apoptosis in culture. It also increases PPAR-γ expression and decreases NF-κB DNA-binding activity, which may be involved in these effects.

The role of c-FLIP in cisplatin resistance of human bladder cancer cells

PURPOSE

We investigated the mechanisms underlying cisplatin resistance in human bladder cancer cells to provide novel molecular targets for the treatment of cisplatin resistant bladder cancer.

MATERIALS AND METHODS

The differential gene expression of cisplatin sensitive (T24) and resistant (T24R2) human bladder cancer cell lines was analyzed and validated by microarray and Western blot analysis. Changes in cisplatin sensitivity by c-FLIP knockdown and related mechanisms in T24R2 cells were assessed using the Cell Counting Kit-8 assay (Dojindo Molecular Technologies, Gaithersburg, Maryland) and Western blot. siRNA oligonucleotides that specifically target c-FLIP were prepared and siRNA transfection was done.

RESULTS

Microarray analysis revealed that the expression of 1,086 and 322 genes showed more than twofold and fourfold changes in the T24R2 and T24 cell lines, respectively. Especially genes involved in the c-FLIP related death receptor apoptosis pathway, including caspase 2 and 9, NF-kB, BID, c-FLIP, XIAP, and cIAP1 and 2, showed differential expression in the 2 cell lines. Western blot demonstrated complete cisplatin mediated suppression of c-FLIP expression in T24 cells but no change in c-FLIP expression was observed in T24R2 cells after cisplatin treatment in the same dose range. Suppression of c-FLIP expression in T24R2 cells by siRNA transfection rendered these cells significantly more sensitive to cisplatin treatment than untransfected T24R2 cells (p <0.05).

CONCLUSIONS

Results reveal that c-FLIP has an important role in the cisplatin resistance of human bladder cancer cells and c-FLIP modulation may at least partially reverse cisplatin resistance in bladder cancer cells.

Molecular mechanisms of cisplatin resistance in bladder cancer

Metastatic disease is the most common mechanism of death in patients with advanced bladder cancer. As for most solid tumors, chemotherapy remains the only realistic option for palliating or curing metastatic disease. However, bladder cancer is characterized by chemoresistance. Only modest response rates are obtained using multiagent regimens including cisplatin. These low response rates and the toxicity of these regimens limit their use to patients at highest risk. Here, we review the molecular mechanisms of cisplatin resistance. These include methods to reduce cisplatin bioavailability within a cell, and defects in the machinery that produces cell death following cisplatin-induced DNA damage. While overcoming these mechanisms is a potential therapeutic approach that can increase response rates, in the short term this knowledge could be used to predict response in individual tumors.

Inflammatory pathways as promising targets to increase chemotherapy response in bladder cancer

While more and more physicians are choosing chemotherapy for patients with bladder cancer, the current treatment is still far from satisfactory due to low response rate and severe side effects. Emerging evidence indicates that inflammatory microenvironment is involved in the pathogenesis of bladder cancer. Recent studies have also provided ample evidence that chemotherapy response is influenced by activation of major inflammatory mediators, including transcription factors, cytokines, chemokines, and COX-2. We reviewed all published literature addressing the roles of inflammatory microenvironment in bladder cancer and evaluating emerging evidence that inflammatory pathways represent potential therapeutic targets to enhance chemotherapy of bladder cancer.

BCL2A1: the underdog in the BCL2 family

B-cell lymphoma 2 (BCL2) proteins are important cell death regulators, whose main function is to control the release of cytochrome c from mitochondria in the intrinsic apoptotic pathway. They comprise both pro- and anti-apoptotic proteins, which interact in various ways to induce or prevent pore formation in the outer mitochondrial membrane. Due to their central function in the apoptotic machinery, BCL2 proteins are often deregulated in cancer. To this end, many anti-apoptotic BCL2 proteins have been identified as important cellular oncogenes and attractive targets for anti-cancer therapy. In this review, the existing knowledge on B-cell lymphoma 2-related protein A1 (BCL2A1)/Bcl-2-related gene expressed in fetal liver (Bfl-1), one of the less extensively studied anti-apoptotic BCL2 proteins, is summarized. BCL2A1 is a highly regulated nuclear factor κB (NF-κB) target gene that exerts important pro-survival functions. In a physiological context, BCL2A1 is mainly expressed in the hematopoietic system, where it facilitates survival of selected leukocytes subsets and inflammation. However, BCL2A1 is overexpressed in a variety of cancer cells, including hematological malignancies and solid tumors, and may contribute to tumor progression. Therefore, the development of small molecule inhibitors of BCL2A1 may be a promising approach mainly to sensitize tumor cells for apoptosis and thus improve the efficiency of anti-cancer therapy.

The C-terminal region of Bfl-1 sensitizes non-small cell lung cancer to gemcitabine-induced apoptosis by suppressing NF-κB activity and down-regulating Bfl-1

Gemcitabine is used to treat several cancers including lung cancer. However, tumor cells often escape gemcitabine-induced cell death via various mechanisms, which include modulating bcl-2 family members and NF-κB activation. We previously reported that the C-terminal region of Bfl-1 fused with GFP (BC) is sufficient to induce apoptosis in 293T cells. In the present study, we investigated the anti-tumor effect of combined BC gene therapy and gemcitabine chemotherapy in vitro and in vivo using non-small cell lung cancer cell lines and a xenograft model. Cell lines were resistant to low dose gemcitabine (4-40 ng/ml), which induced NF-κB activation and concomitant up-regulation of Bfl-1 (an NF-κB-regulated anti-apoptotic protein). BC induced the apoptosis of A549 and H157 cells with caspase-3 activation. Furthermore, co-treatment with BC and low dose gemcitabine synergistically and efficiently induced mitochondria-mediated apoptosis in these cells. When administered alone or with low dose gemcitabine, BC suppressed NF-κB activity, inhibited the nuclear translocation of p65/relA, and down-regulated Bfl-1 expression. Furthermore, direct suppression of Bfl-1 by RNA interference sensitized cells to gemcitabine-induced cell death, suggesting that Bfl-1 importantly regulates lung cancer cell sensitivity to gemcitabine. BC and gemcitabine co-treatment also showed a strong anti-tumor effect in a nude mouse/A549 xenograft model. These results suggest that lung cancer cells become resistant to gemcitabine via NF-κB activation and the subsequent overexpression of Bfl-1, and that BC, which has both pro-apoptotic and NF-κB inhibitory effects, could be harnessed as a gene therapy to complement gemcitabine chemotherapy in non-small cell lung cancer.

Nuclear Factor-kappa B as a Resistance Factor to Platinum-Based Antineoplasic Drugs

Platinum drugs continue to be major chemotherapy drugs for cancer treatment. Nevertheless, acquired or intrinsic resistance to these compounds is common in human tumors. One important mechanism for this resistance is the avoidance of cells entering the apoptotic pathway. Nuclear factor-kappa B (NF-kappa B, NF-κB) is a pleiotropic transcription factor key in determining the death threshold of human cells. This factor is important in the final response of cells to platinum drugs, as exemplified by in vitro and in vivo models showing that inhibition of NF-κB sensitizes cancer cells to the effects of these drugs. New approaches focusing on the inhibition of NF-κB could help to minimize or even eliminate intrinsic or acquired resistance to platinum drugs.

Bcl2-A1 interacts with pro-caspase-3: implications for amyotrophic lateral sclerosis

Expression of mutant SOD1 typical of familial amyotrophic lateral sclerosis (ALS) induces the expression of Bcl2-A1, a member of the Bcl2 family of proteins, specifically in motor neurons of transgenic mice. In this work, we have used immortalized motor neurons (NSC-34) and transgenic mice expressing mutant SOD1 to unravel the molecular mechanisms and the biological meaning of this up-regulation. We report that up-regulation of Bcl2-A1 by mutant SOD1 is mediated by activation of the redox sensitive transcription factor AP1 and that Bcl2-A1 interacts with pro-caspase-3 via its C-terminal helix α9. Furthermore, Bcl2-A1 inhibits pro-caspase-3 activation in immortalized motor neurons expressing mutant SOD1 and thus induction of Bcl2-A1 in ALS mice represents a pro-survival strategy aimed at counteracting the toxic effects of mutant SOD1. These data provide significant new insights on how molecular signaling, driven by expression of the ALS-causative gene SOD1, affects regulation of apoptosis in motor neurons and thus may have implications for ALS therapy, where prevention of motor neuronal cell death is one of the major aims.

A schizont-derived protein, TpSCOP, is involved in the activation of NF-kappaB in Theileria parva-infected lymphocytes

Theileria parva is a tick-transmitted intracellular protozoan parasite that causes East Coast fever, a fatal bovine lymphoproliferative disease. The molecular mechanisms that underlie host cell transformation by T. parva schizonts have been studied extensively, and it is known that the nuclear factor-kappa B (NF-kappaB) is activated in schizont-infected cells, making T. parva-transformed cells resistant to apoptosis. However, the mechanism by which the parasite triggers the activation of NF-kappaB remains enigmatic. In the present study, we biochemically characterized a novel protein, which we termed TpSCOP (T. parvaschizont-derived cytoskeleton-binding protein), which is expressed in the schizont stage of T. parva. TpSCOP was shown to interact with F-actin in vitro. Expression of TpSCOP in a murine lymphocytic cell line resulted in the activation of NF-kappaB signaling pathways, leading to apoptosis resistance. The activation of mitogen-activated protein kinase (MAPK), including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), was also detected. Furthermore, the introduction of TpSCOP into T. parva-infected cells also enhanced the activation of NF-kappaB. This is the first report to demonstrate that a parasite-derived molecule has the ability to activate the host NF-kappaB pathway. Based on these results, TpSCOP likely plays an important role in apoptosis inhibition during Theileria infection.

Human telomerase reverse transcriptase (hTERT): a target molecule for the treatment of cisplatin-resistant tumors

BACKGROUND

Human telomerase reverse transcriptase (hTERT) is a catalytic enzyme that is required for telomerase activity (TA) and cancer progression. Telomerase inhibition or inactivation increases cellular sensitivity to UV irradiation, DNA-damaging agents, the tyrosine kinase inhibitor, imatinib, and pharmacological inhibitors, such as BIBR1532. hTERT is associated with apoptosis. Some patients show drug-resistance during anti-cancer drug treatment and the cancer cell acquire anti-apoptotic mechanism. Therefore, we attempted to study correlation between hTERT and drug-resistance.

METHODS

To study the correlation between protein level and activity of hTERT and drug-resistance, Western blotting and telomerase repeat amplification protocol (TRAP) assays were performed. To investigate whether hTERT contributes to drug resistance in tumor cells, we transiently decreased hTERT levels using small interfering RNA (siRNA) in T24/R2 cells.

RESULTS

hTERT knockdown increased Bax translocation into the mitochondria and cytochrome C release into the cytosol. Caspase inhibitors, especially Z-VAD-FMK, rescued this phenomenon, suggesting that the stability or expression of hTERT might be regulated by caspase activity.

CONCLUSIONS

These data suggest that hTERT might be a target molecule for drug-resistant tumor therapy.

The proteasome inhibitor bortezomib in combination with gemcitabine and carboplatin in advanced non-small cell lung cancer: a California Cancer Consortium Phase I study

INTRODUCTION

Bortezomib is a small-molecule proteasome inhibitor with single-agent activity in patients with non-small cell lung carcinoma (NSCLC) and synergy with gemcitabine in preclinical studies. The combination of gemcitabine and carboplatin is an accepted first-line treatment for advanced NSCLC. We conducted a phase I study of gemcitabine and carboplatin in combination with bortezomib.

METHODS

Bortezomib was administered on days 1, 4, 8, and 11, after gemcitabine on days 1 and 8, and carboplatin on day 1 of a 21-day cycle. Three escalating dose levels were evaluated: bortezomib 1.0 mg/m2/gemcitabine 800 mg/m2, bortezomib 1.0 mg/m2/gemcitabine 1000 mg/m2, and bortezomib 1.3 mg/m2/gemcitabine 1000 mg/m2, in combination with carboplatin AUC 5.0.

RESULTS

Twenty-six patients with advanced NSCLC were treated; 21 were chemotherapy-naive. The median age was 59 years (range, 34-74), and 23 patients were stage IV. The Karnofsky performance score was <or=80% in 10 and >80% in 16 patients. Dose-limiting toxicities were grade 3 thrombocytopenia with bleeding and febrile neutropenia accompanied by grade 4 thrombocytopenia and grade 3 hyponatremia. The maximum-tolerated dose was defined as bortezomib 1.0 mg/m2, gemcitabine 1000 mg/m2, and carboplatin AUC 5.0. The most common grade 3/4 toxicities were thrombocytopenia (rarely associated with bleeding), and neutropenia. Nine of 26 patients (35%) achieved partial response, and eight patients had stable disease.

CONCLUSIONS

The combination of bortezomib 1.0 mg/m2, gemcitabine 1000 mg/m2, and carboplatin AUC 5.0 demonstrated manageable toxicities and encouraging activity in NSCLC. This regimen was used in a phase II study.

Glucocorticoids modulate NF-kappaB-dependent gene expression by up-regulating FKBP51 expression in Newcastle disease virus-infected chickens

FK506-binding protein 51(FKBP51, coded by FKBP5) is a co-chaperone molecule that interacts with the chaperone HSP90 and the glucocorticoid receptor (GR) in an inactive GR complex. It is a negative regulator of glucocorticoid action and is replaced by the positive regulator, FK506-binding protein 52 (FKBP52, coded by FKBP4) when hormone binds to GR, which renders the GR complex active. In this study, we found that the expression of FKBP51 mRNA in 12 organs of Newcastle disease virus (NDV)-infected chickens was robustly induced. The level of corticosterone in NDV-infected chickens was also elevated, approximately 2- to 6.5-fold in the organs compared to non-infected control chickens. The induction of FKBP51 mRNA expression was reproduced by dexamethasone treatment, indicating a role for glucocorticoids in the systemic induction of FKBP51 mRNA expression. In chicken UMNSAH/DF-1 cells, nuclear factor kappaB (NF-kappaB) was activated in an FKBP51-dependent manner. Regulation of the three NF-kappaB-dependent, anti-apoptotic genes, bcl-2, bcl-x and bfl-1/A1 was investigated in UMNSAH/DF-1 cells. Dexamethasone treatment of UMNSAH/DF-1 cells resulted in up-regulation of bcl-2, and down-regulation of bcl-x and bfl-1/A1. Expression of FKBP51 also resulted in down-regulation of bfl-1/A1, but had no effect on bcl-2 and bcl-x, suggesting the involvement of glucocorticoid-FKBP51-NF-kappaB signaling in the regulation of expression of bfl-1/A1 in UMNSAH/DF-1 cells. We observed organ-specific up- or down-regulation of expression of, bcl-2, bcl-x and bfl-1/A1 in NDV-infected and dexamethasone-treated chickens. Differential regulation of bfl-1/A1, bcl-2 and bcl-x upon NDV-infection and dexamethasone treatment suggests that additional factors are involved in the regulation of these genes. These results suggest that systemic elevation of FKBP51 in NDV-infected chickens activates NF-kappaB, which cooperates with other factors to regulate the expression of NF-kappaB-dependent genes.

Incorporating bortezomib into the treatment of lung cancer

Bortezomib, a small-molecule proteasome inhibitor, has activity in lung cancer both as a single agent and in combination with agents commonly used in lung cancer. The ability of bortezomib to favorably modulate the expression of apoptosis-associated proteins, along with its moderate toxicity as a single agent, provides the basis for its combination with cytotoxic agents in the treatment of lung cancer. In non-small cell lung cancer, bortezomib as a single agent has limited activity but in combination with chemotherapy has shown encouraging activity without significantly adding to toxicity. Bortezomib as a single agent has shown minimal activity in small cell lung cancer. Although the role of bortezomib in lung cancer is uncertain, it is likely to have its greatest clinical benefit when given in combination with other therapeutics. Ongoing studies are focused on optimizing the scheduling of bortezomib with chemotherapy, investigating its combination with targeted agents and radiation, and examining its efficacy in a specific subgroup, bronchioloalveolar carcinoma.

Upregulation of bfl-1 is a potential mechanism of chemoresistance in B-cell chronic lymphocytic leukaemia

B-cell chronic lymphocytic leukaemia (B-CLL) is characterised by the progressive accumulation of monoclonal CD5(+) B cells. In a previous study, we have analysed the expression profile of apoptosis-regulating genes using a cDNA-based microarray and found overexpression of the antiapoptotic bcl-2 family member, bfl-1, in B-CLL cells with an apoptosis-resistant phenotype. In this study, bfl-1 mRNA levels have been determined by competitive PCR in an extended population of B-CLL patients to characterise its role in disease progression and development of chemoresistance. bfl-1 levels were significantly higher in patients with no response (NR) to last chemotherapy than in patients responding (partial response (PR)) to last chemotherapy (P<0.05) and in patients who had not required treatment (P<0.05). We found no correlation between bfl-1 mRNA levels and disease progression, IGHV mutational status or other clinical parameters. In addition, bfl-1 mRNA levels were inversely correlated with apoptotic response to in vitro fludarabine treatment of B-CLL cells. Specific downregulation of bfl-1 using siRNA induced apoptosis in resistant cells. Our data suggest that bfl-1 contributes to chemoresistance and might be a therapeutic target in B-CLL.

Mechanisms of resistance to cisplatin and carboplatin

While cisplatin and carboplatin are active versus most common cancers, epithelial malignancies are incurable when metastatic. Even if an initial response occurs, acquired resistance due to mutations and epigenetic events limits efficacy. Resistance may be due to excess of a resistance factor, to saturation of factors required for tumor cell killing, or to mutation or alteration of a factor required for tumor cell killing. Platinum resistance could arise from decreased tumor blood flow, extracellular conditions, reduced platinum uptake, increased efflux, intracellular detoxification by glutathione, etc., decreased binding (e.g., due to high intracellular pH), DNA repair, decreased mismatch repair, defective apoptosis, antiapoptotic factors, effects of several signaling pathways, or presence of quiescent non-cycling cells. In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.

BCL2 family of apoptosis-related genes: functions and clinical implications in cancer

One of the most effective ways to combat different types of cancer is through early diagnosis and administration of effective treatment, followed by efficient monitoring that will allow physicians to detect relapsing disease and treat it at the earliest possible time. Apoptosis, a normal physiological form of cell death, is critically involved in the regulation of cellular homeostasis. Dysregulation of programmed cell death mechanisms plays an important role in the pathogenesis and progression of cancer as well as in the responses of tumours to therapeutic interventions. Many members of the BCL2 (B-cell CLL/lymphoma 2; Bcl-2) family of apoptosis-related genes have been found to be differentially expressed in various malignancies, and some are useful prognostic cancer biomarkers. We have recently cloned a new member of this family, BCL2L12, which was found to be differentially expressed in many tumours. Most of the BCL2 family genes have been found to play a central regulatory role in apoptosis induction. Results have made it clear that a number of coordinating alterations in the BCL2 family of genes must occur to inhibit apoptosis and provoke carcinogenesis in a wide variety of cancers. However, more research is required to increase our understanding of the extent to which and the mechanisms by which they are involved in cancer development, providing the basis for earlier and more accurate cancer diagnosis, prognosis and therapeutic intervention that targets the apoptosis pathways. In the present review, we describe current knowledge of the function and molecular characteristics of a series of classic but also newly discovered genes of the BCL2 family as well as their implications in cancer development, prognosis and treatment.

Shared biology of GVHD and GVT effects: Potential methods of separation

The difficult separation of clinical graft-versus-tumor (GVT) effects from graft-versus-host disease (GVHD) reflects their shared biology. Experimental approaches to mediate GVT effects while limiting GVHD include: (1) allograft T cell depletion followed by immune enhancement; (2) modulation of T cell dose or T cell subset composition; (3) donor lymphocyte infusion; (4) reduced-intensity host preparation; (5) modulation of Th1/Th2 and Tc1/Tc2 cell balance; (6) cytokine therapy or neutralization; (7) T regulatory cell therapy; (8) co-stimulatory pathway modulation; (9) chemokine pathway modulation; (10) induction of antigen-specific T cells; (11) alloreactive NK cell therapy; and (12) targeted pharmaceutical inhibition of proteosome, mammalian target of rapamycin, and histone deacetylase pathways. Clearly, a multitude of approaches exist that hold promise for separating GVT effects from GVHD. Future success in this endeavor will require a strong commitment towards translational research and continued advances in cell, vaccine, cytokine, monoclonal antibody, and targeted molecular therapy.

Bortezomib-Based Combinations in the Treatment of Non–Small-Cell Lung Cancer

Lung cancer is the most common cause of cancer-related death among men and women in the United States. Current trials are focusing on the integration of novel therapeutic agents into current non-small-cell lung cancer (NSCLC) treatment paradigms. Bortezomib, a small-molecule proteasome inhibitor, has single-agent activity in NSCLC and in combination with agents commonly used in NSCLC. This article will review the rationale and preclinical data supporting bortezomib combinations and the clinical trials with bortezomib alone and in combination in NSCLC to date.