NF-kappa B-mediated chemoresistance in breast cancer cells

EEBR induces Caspase-1-dependent pyroptosis through the NF-κB/NLRP3 signalling cascade in non-small cell lung cancer

Lung cancer is a leading cause of cancer-related deaths worldwide. Recent studies have identified pyroptosis, a type of programmed cell death, as a critical process in the development and progression of lung cancer. In this study, we investigated the effect of EEBR, a new compound synthesized by our team, on pyroptosis in non-small cell lung cancer cells (NSCLC) and the underlying molecular mechanisms. Our results demonstrated that EEBR significantly reduced the proliferation and metastasis of NSCLC cells in vitro. Moreover, EEBR-induced pyroptosis in NSCLC cells, as evidenced by cell membrane rupture, the release of cytokines such as interleukin-18 and interleukin-1 beta and the promotion of Gasdermin D cleavage in a Caspase-1-dependent manner. Furthermore, EEBR promoted the nuclear translocation of NF-κB and upregulated the protein level of NLRP3. Subsequent studies revealed that EEBR-induced pyroptosis was suppressed by the inhibition of NF-κB. Finally, EEBR effectively suppressed the growth of lung cancer xenograft tumours by promoting NSCLC pyroptosis in animal models. Taken together, our findings suggest that EEBR induces Caspase-1-dependent pyroptosis through the NF-κB/NLRP3 signalling cascade in NSCLC, highlighting its potential as a candidate drug for NSCLC treatment.

Curcumin as an Enhancer of Therapeutic Efficiency of Chemotherapy Drugs in Breast Cancer

Female breast cancer is the world’s most prevalent cancer in 2020. Chemotherapy still remains a backbone in breast cancer therapy and is crucial in advanced and metastatic breast cancer treatment. The clinical efficiency of chemotherapy regimens is limited due to tumor heterogeneity, chemoresistance, and side effects. Chemotherapeutic drug combinations with natural products hold great promise for enhancing their anticancer efficacy. Curcumin is an ideal chemopreventive and chemotherapy agent owning to its multitargeting function on various regulatory molecules, key signaling pathways, and pharmacological safety. This review aimed to elucidate the potential role of curcumin in enhancing the efficacy of doxorubicin, paclitaxel, 5-fluorouracil, and cisplatin via combinational therapy. Additionally, the molecular mechanisms underlying the chemosensitizing activity of these combinations have been addressed. Overall, based on the promising therapeutic potential of curcumin in combination with conventional chemotherapy drugs, curcumin is of considerable value to develop as an adjunct for combination chemotherapy with current drugs to treat breast cancer. Furthermore, this topic may provide the frameworks for the future research direction of curcumin–chemotherapy combination studies and may benefit in the development of a novel therapeutic strategy to maximize the clinical efficacy of anticancer drugs while minimizing their side effects in the future breast cancer treatment.

Anti-carcinogenic Effect of Cathepsin K Inhibitor, Odanacatib with a Low Dose of Cisplatin Against Human Breast Carcinoma MCF-7 and MDA-MB231 Cells

Background:

A cross-linking agent commonly used for cancer chemotherapy is a platinum compound such as cisplatin. However, with the acquisition of cellular drug resistance and adverse side effects, the potency of cisplatin is, therefore, often tempered. To overcome these issues, the present study has established the use of cathepsin k (CTSK) inhibitor as a potent chemosensitizer.

Methods:

The cytotoxic effect of cisplatin and odanacatib (ODN) on two different breast cancer patient- derived cell lines, MDA-MB-231 and MCF-7, was assessed by MTT-based colorimetric assay. The drug interaction coefficient CDI was used to evaluate the synergistically inhibitory impact of the drug combination and immunoblot was used to examine the expression of certain proteins responsible for cell survival and the mechanism of apoptosis.

Results:

In this study, we found that IC50 of ODN in combination with cisplatin (half of IC25) induced a synergistic cytotoxic effect in different breast cancer cells. Diminished expression of Bcl-2 and increased expression of Bax aroused the cytochrome release, that triggered caspase-9 and -3 activation in the combinatorial group. ODN with a lower dose of cisplatin significantly inhibited the protein expression of novel chemoresistant factors such as STAT3, NFκB and IL-6.

Conclusion:

This study highlights the potential effects of the combination of ODN with a reduced dose of cisplatin on improving the growth inhibition and apoptosis-inducing effect on breast cancer cells via combined inhibition of NF-κB-induced IL-6 and STAT3 activation. The study result suggests that the further development of this novel inhibitor in combination with a low dose of standard cisplatin-based chemotherapy may contribute to an alternative treatment option for certain cancers.

New uracil analog U-332 is an inhibitor of NF-κB in 5-fluorouracil-resistant human leukemia HL-60 cell line

BACKGROUND

5-Fluorouracil (5-FU) is an antimetabolite that interferes with DNA synthesis and has been widely used as a chemotherapeutic drug in various types of cancers. However, the development of drug resistance greatly limits its application. Overexpression of ATP-binding cassette (ABC) transporters in many types of cancer is responsible for the reduction of the cellular uptake of various anticancer drugs causing multidrug resistance (MDR), the major obstacle in cancer chemotherapy. Recently, we have obtained a novel synthetic 5-FU analog, U-332 [(R)-3-(4-bromophenyl)-1-ethyl-5-methylidene-6-phenyldihydrouracil], combining a uracil skeleton with an exo-cyclic methylidene group. U-332 was highly cytotoxic for HL-60 cells and showed similar cytotoxicity in the 5-FU resistant subclone (HL-60/5FU), in which this analog almost completely abolished expression of the ATP-binding cassette (ABC) transporter, multidrug resistance associate protein 1 (ABCC1). The expression of ABC transporters is usually correlated with NF-κB activation. The aim of this study was to determine the level of NF-κB subunits in the resistant HL-60/5-FU cells and to evaluate the potential of U-332 to inhibit activation of NF-κB family members in this cell line.

METHODS

Anti-proliferative activity of compound U-332 was assessed by the MTT assay. In order to disclose the mechanism of U-332 cytotoxicity, quantitative real-time PCR analysis of the NF-κB family genes, c-Rel, RelA, RelB, NF-κB1, and NF-κB2, was investigated. The ability of U-332 to reduce the activity of NF-κB members was studied by ELISA test.

RESULTS

In this report it was demonstrated, using RT-PCR and ELISA assay, that members of the NF-κB family c-Rel, RelA, RelB, NF-κB1, and NF-κB2 were all overexpressed in the 5-FU-resistant HL-60/5FU cells and that U-332 potently reduced the activity of c-Rel, RelA and NF-κB1 subunits in this cell line.

CONCLUSIONS

This finding indicates that c-Rel, RelA and NF-κB1 subunits are responsible for the resistance of HL-60/5FU cells to 5-FU and that U-332 is able to reverse this resistance. U-332 can be viewed as an important lead compound in the search for novel drug candidates that would not cause multidrug resistance in cancer cells.

The Effect of P-Glycoprotein (P-gp), Nuclear Factor-Kappa B (Nf-κb), and Aldehyde Dehydrogenase-1 (ALDH-1) Expression on Metastases, Recurrence and Survival in Advanced Breast Cancer Patients

Objective: To investigate the level of three drug resistance proteins; P-glycoprotein 1 (P-gp), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and aldehyde dehydrogenase isoform 1 (ALDH1) expression and their relationship to metastasis, recurrence and survival in advanced breast cancer patients that received neoadjuvant chemotherapy. Methods: This study is a combination of prospective and retrospective cohort study involving one hundred and thirty one cases of advanced stage invasive breast cancer that have received neoadjuvant chemotherapy. Initial biopsy specimens (incisional biopsy or core biopsy) were taken from paraffin blocks. Immunohistochemistry (IHC) was used to detect P-gp, NF-κB, and ALDH1 expression. Prospectively analysed patients were followed for five years and evaluated for recurrence and death. Results: The expression of P-gp has no significant statistical correlation to metastases (p = 0.659), recurrence (p = 0.862) and survival (p = 0.835) in advanced stage breast cancer patients who received neoadjuvant chemotherapy. Similarly, ALDH1 was not correlated to metastases (p=0.120), recurrence (p = 0.186) and survival (p = 0.254) statistically. We found that NF-κB expression showed a significant correlation to metastases (p=0.004), recurrence (p = 0.016) and overall survival (p = 0.041) in advanced stage breast cancer patients after neoadjuvant chemotherapy. Conclusion: NF-κB expression is a potential marker that can be used to assess or to predict increasing risk of metastases, recurrence and survival in advanced stage breast cancer patients who receive neoadjuvant chemotherapy.

The oncogenic Golgi phosphoprotein 3 like overexpression is associated with cisplatin resistance in ovarian carcinoma and activating the NF-κB signaling pathway

Background

Chemo-resistance is a leading cause of tumor relapse and treatment failure in patients with ovarian cancer. The identification of effective strategies to overcome drug resistance will have a significant clinical impact on the disease.

Methods

The protein and mRNA expression of GOLPH3L in ovarian cancer cell lines and patient tissues were determined using Real-time PCR and Western blot, respectively. 177 human ovarian cancer tissue samples were analyzed by IHC to investigate the association between GOLPH3L expression and the clinicopathological characteristics of ovarian cancer patients. Functional assays, such as MTT, FACS, and Tunel assay used to determine the oncogenic role of GOLPH3L in human ovarian cancer progression. Furthermore, western blotting and luciferase assay were used to determine the mechanism of GOLPH3L promotes chemoresistance in ovarian cancer cells.

Results

The expression of GOLPH3L was markedly upregulated in ovarian cancer cell lines and tissues, and high GOLPH3L expression was associated with an aggressive phenotype and poor prognosis with ovarian cancer patients. GOLPH3L overexpression confers CDDP resistance on ovarian cancer cells; however, inhibition of GOLPH3L sensitized ovarian cancer cell lines to CDDP cytotoxicity both in vitro and in vivo. Additionally, GOLPH3L upregulated the levels of nuclear p65 and phosphorylated inhibitor of nuclear factor Kappa-B kinase-β and IκBα, thereby activating canonical nuclear factor-κB (NF-κB) signaling.

Conclusions

Our findings suggest that GOLPH3L is a potential therapeutic target for the treatment of ovarian cancer: targeting GOLPH3L signaling may represent a promising strategy to enhance platinum response in patients with chemoresistant ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0607-0) contains supplementary material, which is available to authorized users.

Apoptosis, Chemoresistance, and Breast Cancer: Insights From the MCF-7 Cell Model System

The MCF-7 cell line was derived from a patient with metastatic breast cancer in 1970. Since then it has become a prominent model system for the study of estrogen receptor-positive breast cancer. With this model as a focus, this review summarizes important studies addressing tumor necrosis factor-α as a prototypical apoptosis-inducing cytokine in MCF-7 cells. Both survival and death receptor signaling pathways are discussed in terms of their role in chemotherapy-induced apoptosis as well as in chemoresistance. Novel therapeutic approaches to the treatment of breast cancer are proposed utilizing knowledge of these signaling pathways as targets. Specifically, ceramide metabolism is proposed as a novel target for chemosensitivity, perhaps combined with selective inhibitors of Bcl-2 or PI3K/Akt/nuclear factor-κB. Suggested areas of future research include translational studies manipulating candidate survival and death signaling pathways.

Inhibition of NF-κB Activity Enhances Sensitivity to Anticancer Drugs in Cholangiocarcinoma Cells

Cholangiocarcinoma (CCA) is a dismal cancer. At present, there is no effective chemotherapeutic regimen for CCA. This may be due to the marked resistance of CCA to chemotherapy drugs, for which a mechanism remains unknown. Nuclear factor-κB (NF-κB) is constitutively activated in a variety of cancer cells, including CCA. It has been shown to play roles in growth, metastasis, and chemoresistance of cancer. In the present study, we examined whether NF-κB is involved in the chemoresistance of CCA and whether dehydroxymethylepoxyquinomicin (DHMEQ), an effective NF-κB inhibitor, can overcome the drug resistance of CCA. Two CCA cell lines, KKU-M213 and KKU-M214, were treated with DHMEQ and/or chemotherapeutic drugs. Cell viability, apoptosis, and the expressions of the ATP-binding cassette (ABC) transporters were compared. The combination of chemotherapy drugs, 5-fluorouracil, cisplatin, and doxorubicin, with DHMEQ significantly enhanced the cytotoxicity of all chemotherapeutic drugs compared to DHMEQ or drug alone. Furthermore, the mRNA level of ABCB1, a multidrug-resistant protein, was significantly decreased in the 5-fluorouracil combined with DHMEQ-treated cells. These findings suggest that the inhibition of NF-κB by DHMEQ enhanced the chemoresponsiveness of CCA cells, possibly by reducing the expression of ABC transporter. Inhibition of NF-κB may be a potential chemodrug-sensitizing strategy for chemoresistant cancer such as CCA.

Elevated NIBP/TRAPPC9 mediates tumorigenesis of cancer cells through NFκB signaling

Regulatory mechanisms underlying constitutive and inducible NFκB activation in cancer remain largely unknown. Here we investigated whether a novel NIK- and IKK2-binding protein (NIBP) is required for maintaining malignancy of cancer cells in an NFκB-dependent manner. Real-time polymerase chain reaction analysis of a human cancer survey tissue-scan cDNA array, immunostaining of a human frozen tumor tissue array and immunoblotting of a high-density reverse-phase cancer protein lysate array showed that NIBP is extensively expressed in most tumor tissues, particularly in breast and colon cancer. Lentivirus-mediated NIBP shRNA knockdown significantly inhibited the growth/proliferation, invasion/migration, colony formation and xenograft tumorigenesis of breast (MDA-MB-231) or colon (HCT116) cancer cells. NIBP overexpression in HCT116 cells promoted cell proliferation, migration and colony formation. Mechanistically, NIBP knockdown in cancer cells inhibited cytokine-induced activation of NFκB luciferase reporter, thus sensitizing the cells to TNFα-induced apoptosis. Endogenous NIBP bound specifically to the phosphorylated IKK2 in a TNFα-dependent manner. NIBP knockdown transiently attenuated TNFα-stimulated phosphorylation of IKK2/p65 and degradation of IκBα. In contrast, NIBP overexpression enhanced TNFα-induced NFκB activation, thus inhibiting constitutive and TNFα-induced apoptosis. Collectively, our data identified important roles of NIBP in promoting tumorigenesis via NFκΒ signaling, spotlighting NIBP as a promising target in cancer therapeutic intervention.

LDOC1 inhibits proliferation and promotes apoptosis by repressing NF-κB activation in papillary thyroid carcinoma

Background

The incidence of thyroid cancer has progressively increased over the past few decades, and the most frequent types of this cancer are papillary thyroid carcinoma (PTC) and small primary tumors. In PTC, oncogene activation is known to occur at a high frequency. However, the potential roles of tumor suppressor genes in thyroid carcinogenesis remain unclear. LDOC1 was first identified as a gene encoding a leucine zipper protein whose expression was decreased in a series of pancreatic and gastric cancer cell lines. In this study, we aimed to determine the status of LDOC1 in PTC and identify its mechanistic role in PTC pathogenesis.

Methods

LDOC1 expression was evaluated in fresh samples and stored specimens of human PTC and contralateral normal tissues by performing quantitative reverse transcription-PCR and immunohistochemical staining. The correlation to nuclear p65 content in the stored specimens was analyzed. Moreover, the basal level of LDOC1 in two human PTC-derived cell lines (BCPAP and TPC-1) compared with normal thyroid tissue was determined. Human LDOC1 cDNA was inserted into a lentiviral vector and transduced into TPC-1 cells. TPC-1 cells overexpressing LDOC1/GFP (Lv-LDOC1) or negative control GFP (Lv-NC) were stimulated with TNFα or recombinant TGF-β1, and then cell proliferation, cell cycle distribution, and apoptosis were assessed. Western blotting was used to examine the expression of p65, IκBα, c-Myc, Bax, and Bcl-xL, and a luciferase reporter assay was used to measure NF-κB activity stimulated by TNFα. Statistical significance was determined using Student’s t tests or ANOVA and Newman-Keuls multiple comparison tests. Pearson chi-square test was used to analyze possible associations.

Results

LDOC1 expression was significantly downregulated in PTC specimens as compared with the expression in normal thyroid tissues, and this downregulation was associated with an increase in tumor size (P < 0.05). There is a correlation between LDOC1 and nuclear P65 expression in human PTC tissues (P < 0.01). Lentivirus-mediated restoration of LDOC1 expression in TPC-1 cells characterized by low level of LDOC1 expression suppressed proliferation and induced apoptosis by inhibiting NF-κB activation, and LDOC1-overexpressing TPC-1 cells recovered responsiveness to TGF-β1 antiproliferative signaling.

Conclusions

LDOC1 might function as a tumor suppressor gene in PTC by inhibiting NF-κΒ signaling, and thus might represent a promising therapeutic target in patients with PTC.

Hydrogen sulfide-releasing naproxen suppresses colon cancer cell growth and inhibits NF-κB signaling

Colorectal cancer (CRC) is the second leading cause of death due to cancer and the third most common cancer in men and women in the USA. Nuclear factor kappa B (NF-κB) is known to be activated in CRC and is strongly implicated in its development and progression. Therefore, activated NF-κB constitutes a bona fide target for drug development in this type of malignancy. Many epidemiological and interventional studies have established nonsteroidal anti-inflammatory drugs (NSAIDs) as a viable chemopreventive strategy against CRC. Our previous studies have shown that several novel hydrogen sulfide-releasing NSAIDs are promising anticancer agents and are safer derivatives of NSAIDs. In this study, we examined the growth inhibitory effect of a novel H₂S-releasing naproxen (HS-NAP), which has a repertoire as a cardiovascular-safe NSAID, for its effects on cell proliferation, cell cycle phase transitions, and apoptosis using HT-29 human colon cancer cells. We also investigated its effect as a chemo-preventive agent in a xenograft mouse model. HS-NAP suppressed the growth of HT-29 cells by induction of G₀/G₁ arrest and apoptosis and downregulated NF-κB. Tumor xenografts in mice were significantly reduced in volume. The decrease in tumor mass was associated with a reduction of cell proliferation, induction of apoptosis, and decreases in NF-κB levels in vivo. Therefore, HS-NAP demonstrates strong anticancer potential in CRC.

pH-Sensitive pullulan–DOX conjugate nanoparticles for co-loading PDTC to suppress growth and chemoresistance of hepatocellular carcinoma

Co-delivery of DOX and PDTC using pH-sensitive pullulan–DOX conjugate nanoparticles helped to suppress growth and chemoresistance of hepatocellular carcinoma.

Elevated expression of long intergenic non-coding RNA HOTAIR in a basal-like variant of MCF-7 breast cancer cells

Epigenetic regulation of gene expression is critical to phenotypic maintenance and transition of human breast cancer cells. HOX antisense intergenic RNA (HOTAIR) is a long intergenic non-coding RNA that epigenetically represses gene expression via recruitment of enhancer of zeste homolog 2 (EZH2), a histone methyltransferase. Elevated expression of HOTAIR promotes progression of breast cancer. In the current study we examined the expression and function of HOTAIR in MCF-7-TNR cells, a derivative of the luminal-like breast cancer cell line MCF-7 that acquired resistance to TNF-α-induced cell death. The expression of HOTAIR, markers of the luminal-like and basal-like subtypes, and growth were compared between MCF-7 and MCF-7-TNR cells. These variables were further assessed upon inhibition of HOTAIR, EZH2, p38 MAPK, and SRC kinase in MCF-7-TNR cells. When compared with MCF-7 cells, MCF-7-TNR cells exhibited an increase in the expression of HOTAIR, which correlated with characteristics of a luminal-like to basal-like transition as evidenced by dysregulated gene expression and accelerated growth. MCF-7-TNR cells exhibited reduced suppressive histone H3 lysine27 trimethylation on the HOTAIR promoter. Inhibition of HOTAIR and EZH2 attenuated the luminal-like to basal-like transition in terms of gene expression and growth in MCF-7-TNR cells. Inhibition of p38 and SRC diminished HOTAIR expression and the basal-like phenotype in MCF-7-TNR cells. HOTAIR was robustly expressed in the native basal-like breast cancer cells and inhibition of HOTAIR reduced the basal-like gene expression and growth. Our findings suggest HOTAIR-mediated regulation of gene expression and growth associated with the basal-like phenotype of breast cancer cells.

Anti-cancer activity of new designer hydrogen sulfide-donating hybrids

SIGNIFICANCE

Hydrogen sulfide (H2S) is likely to join nitric oxide (NO) and carbon monoxide (CO) as the third gaseous transmitter, influencing an array of intracellular signaling cascades. Thus, H2S is implicated in numerous physiological processes and in the pathology of various diseases.

RECENT ADVANCES

H2S-donating agents that liberate H2S slowly either alone or in combination with NO, the so-called NOSH compounds, are being synthesized, and these have been shown to have great potential against cancer.

CRITICAL ISSUES

An accurate determination of H2S levels is challenging. H2S and NO share many similar actions; do these similarities act to potentiate each other? Since many actions of H2S appear to be mediated through inhibition of inflammation and Nuclear factor kappa-light-chain-enhancer of activated B cells is a central player in this scenario, does S-nitrosylation of this transcription factor by NO affect its S-sulfhydration by H2S and vice versa?

FUTURE DIRECTIONS

Deciphering the molecular targets of these novel hybrid agents and having genetically engineered animals should help us move toward targeted therapeutic applications. Human safety data with these new hybrids is essential.

Overexpressed nuclear BAG-1 in human hepatocellular carcinoma is associated with poor prognosis and resistance to doxorubicin

Bcl-2-associated athanogene-1 (BAG-1) is a multifunctional anti-apoptotic protein which regulates an array of cellular processes, including apoptosis, signaling, proliferation, transcription, and cell motility and has been reported to be over-expressed in a number of human malignancies. To investigate the possible involvement of BAG-1 in tumorigenesis of hepatocellular carcinoma (HCC), we performed Western blot analysis in eight paired samples of HCC and adjacent peritumoral tissues and immunohistochemistry in 65 paraffin sections of HCC, which both showed an enhanced expression of nuclear BAG-1 isoform in HCC tissues. Statistical analysis confirmed that overexpression of nuclear BAG-1 in HCC tissues was significantly associated with histological grading (P < 0.001), poor prognosis (P = 0.004), and was found to be an independent prognostic indicator for HCC (P = 0.023). We also noted that BAG-1 was overexpressed in four HCC cell lines compared with a normal hepatocyte cell line, and BAG-1 overexpression increased resistance of HCC cells to doxorubicin, a common chemotherapeutic agent for HCC. Furthermore, we observed that knock down of BAG-1 with siRNA in HepG2 cells increased the chemosensitivity of cells, a process mediated through inhibition of doxorubicin-triggered NF-κB activation; and knock down of BAG-1 suppressed proliferation and cell cycle transition of HepG2 cells. In consequence, our results for the first time indicated that BAG-1 was dysregulated in HCC and suppression of BAG-1 expression which resulted in inhibiting of NF-κB signaling might be developed into a new strategy in HCC therapy.

The inhibition of metastasis and growth of breast cancer by blocking the NF-κB signaling pathway using bioreducible PEI-based/p65 shRNA complex nanoparticles

Metastasis is one of the greatest challenges in cancer treatment. In this study, a bioreducible polymer, Tween 85-s-s-polyethyleneimine 2K (TSP), was synthesized and used as a non-viral gene vector for p65 shRNA to block NF-κB signaling pathway, thereby inhibiting the growth and metastasis of breast cancer. The TSP/p65 shRNA complex nanoparticles (TSNs) could significantly down-regulate p65 expression in breast cancer cells due to the rapid degradation of TSP with prompt shRNA release, and consequently not only inhibit cell proliferation and invasion, but also induce cell apoptosis and disrupt the tube formation. Most importantly, TSNs showed high accumulation in tumor and almost completely inhibited the growth and metastasis of the breast cancer xenograft in nude mice induced by MDA-MB-435 cells. All these results indicated the promising of TSP as a non-viral gene vector to knock down p65 expression and inhibit the growth and metastasis of breast cancer.

Emodin sensitizes the gemcitabine-resistant cell line Bxpc-3/Gem to gemcitabine via downregulation of NF-κB and its regulated targets

The aim of this study was to evaluate whether emodin can overcome the chemoresistance of the gemcitabine-resistant cancer cell line (Bxpc-3/Gem) in vitro. The cell line Bxpc-3/Gem was derived from the human pancreatic cancer cell line Bxpc-3. We found that Bxpc-3/Gem cells were characterized by a series of morphological changes with a resistance index of 43.51 comparing with the parental cell line. Emodin reduced Bxpc-3/Gem cell proliferation in a dose-dependent manner. Emodin and gemcitabine combination treatments resulted in decreased cell proliferation and increased apoptosis in Bxpc-3/Gem cells. In addition, combination treatments resulted in downregulation of gene and protein expression of MDR-1 (P-gp), NF-κB, XIAP, survivin, as well as inhibition of NF-κB activity and P-gp function. These observations suggest that emodin may sensitize the pancreatic cancer gemcitabine-resistant cell line Bxpc-3/Gem to gemcitabine therapy via inhibition of survival signaling.

Platelets increase survival of adenocarcinoma cells challenged with anticancer drugs: mechanisms and implications for chemoresistance

BACKGROUND AND PURPOSE

Cancer cells grow without the restraints of feedback control mechanisms, leading to increased cancer cell survival. The treatment of cancer is often complicated by the lack of response to chemotherapy leading to chemoresistance and persistent survival of tumour cells. In this work we studied the role of platelets in chemotherapy-induced cancer cell death and survival.

EXPERIMENTAL APPROACH

Human adenocarcinoma cells, colonic (Caco-2) and ovarian (59 M) cells, were incubated with 5-fluorouracil (1-300 µg·mL(-1) ) or paclitaxel (1-200 µg·mL(-1) ) in the presence or absence of platelets (1.5 × 10(8) mL(-1) ) for 1, 24 or 72 h. Following incubation, cancer cells were harvested and cell survival/death was assayed using flow cytometry, Western blotting, real-time PCR, TaqMan® Gene Expression Assays and proteomics.

KEY RESULTS

Human platelets increased the survival of colonic and ovarian adenocarcinoma cells treated with two standard anticancer drugs, 5-fluorouracil and paclitaxel. In the presence of platelets, cancer cells up-regulated anti-apoptotic and down-regulated pro-apoptotic genes, increased the number of cells in the synthesis of DNA and decreased the number in the quiescent phase, increased expression of cyclins, DNA repair proteins and MAPKs. The analysis of platelet-Caco-2 secretome demonstrated the release of the chemokine RANTES, thrombospondin-1, TGF-β and clusterin. Finally, human recombinant RANTES and thrombospondin-1 improved survival of Caco-2 cells challenged with paclitaxel.

CONCLUSIONS AND IMPLICATIONS

These data demonstrate that platelets increase adenocarcinoma cells survival, proliferation and chemoresistance to standard anticancer drugs. Modulating cancer cell-platelet interactions may offer a new strategy to improve the efficacy of chemotherapy.

Inhibition of p38 mitogen-activated protein kinase alters microRNA expression and reverses epithelial-to-mesenchymal transition

Acquired chemoresistance and epithelial-to-mesenchymal transition (EMT) are hallmarks of cancer progression and of increasing clinical relevance. We investigated the role of miRNA and p38 mitogen-activated protein kinase (MAPK) signaling in the progression of breast cancer to a drug-resistant and mesenchymal phenotype. We demonstrate that acquired death receptor resistance results in increased hormone-independent tumorigenesis compared to hormone-sensitive parental cells. Utilizing global miRNA gene expression profiling, we identified miRNA alterations associated with the development of death receptor resistance and EMT progression. We further investigated the role of p38 MAPK in this process, showing dose-dependent inactivation of p38 by its inhibitor RWJ67657 and decreased downstream ATF and NF-κB signaling. Pharmacological inhibition of p38 also decreased chemoresistant cancer tumor growth in xenograft animal models. Interestingly, inhibition of p38 partially reversed the EMT changes found in this cell system, as illustrated by decreased gene expression of the EMT markers Twist, Snail, Slug and ZEB and protein and mRNA levels of Twist, a known EMT promoter, concomitant with decreased N-cadherin protein. RWJ67657 treatment also altered the expression of several miRNAs known to promote therapeutic resistance, including miR-200, miR-303, miR-302, miR-199 and miR-328. Taken together, our results demonstrate the roles of multiple microRNAs and p38 signaling in the progression of cancer and demonstrate the therapeutic potential of targeting the p38 MAPK pathway for reversing EMT in an advanced tumor phenotype.

BAG-1 interacts with the p50-p50 homodimeric NF-κB complex: implications for colorectal carcinogenesis

Understanding the mechanisms that promote aberrant tumour cell survival is critical for the determination of novel strategies to combat colorectal cancer (CRC). We have recently shown that the anti-apoptotic protein BAG-1, highly expressed in pre-malignant and CRC tissue, can potentiate cell survival through regulating NF-κB transcriptional activity. In this study, we identify a novel complex between BAG-1 and the p50-p50 NF-κB homodimers, implicating BAG-1 as a co-regulator of an atypical NF-κB pathway. Importantly, the BAG-1-p50 complex was detected at gene regulatory sequences including the epidermal growth factor receptor (EGFR) and COX-2 (PTGS2) genes. Suppression of BAG-1 expression using small interfering RNA was shown to increase EGFR and suppress COX-2 expression in CRC cells. Furthermore, mouse embryonic fibroblasts derived from the NF-κB1 (p105/p50) knock-out mouse were used to demonstrate that p50 expression was required for BAG-1 to suppress EGFR expression. This was shown to be functionally relevant as attenuation of BAG-1 expression increased ligand activated phosphorylation of EGFR in CRC cells. In summary, this paper identifies a novel role for BAG-1 in modulating gene expression through interaction with the p50-p50 NF-κB complexes. Data presented led us to propose that BAG-1 can act as a selective regulator of p50-p50 NF-κB responsive genes in colorectal tumour cells, potentially important for the promotion of cell survival in the context of the fluctuating tumour microenvironment. As BAG-1 expression is increased in the developing adenoma through to metastatic lesions, understanding the function of the BAG-1-p50 NF-κB complexes may aid in identifying strategies for both the prevention and treatment of CRC.

Protective effect of caffeic acid on paclitaxel induced anti-proliferation and apoptosis of lung cancer cells involves NF-κB pathway

Caffeic acid (CA), a natural phenolic compound, is abundant in medicinal plants. CA possesses multiple biological effects such as anti-bacterial and anti-cancer growth. CA was also reported to induce fore stomach and kidney tumors in a mouse model. Here we used two human lung cancer cell lines, A549 and H1299, to clarify the role of CA in cancer cell proliferation. The growth assay showed that CA moderately promoted the proliferation of the lung cancer cells. Furthermore, pre-treatment of CA rescues the proliferation inhibition induced by a sub-IC₅₀ dose of paclitaxel (PTX), an anticancer drug. Western blot showed that CA up-regulated the pro-survival proteins survivin and Bcl-2, the down-stream targets of NF-κB. This is consistent with the observation that CA induced nuclear translocation of NF-κB p65. Our study suggested that the pro-survival effect of CA on PTX-treated lung cancer cells is mediated through a NF-κB signaling pathway. This may provide mechanistic insights into the chemoresistance of cancer calls.

Hydrogen sulfide-releasing aspirin suppresses NF-κB signaling in estrogen receptor negative breast cancer cells in vitro and in vivo

Hormone-dependent estrogen receptor positive (ER+) breast cancers generally respond well to anti-estrogen therapy. Unfortunately, hormone-independent estrogen receptor negative (ER-) breast cancers are aggressive, respond poorly to current treatments and have a poor prognosis. New approaches and targets are needed for the prevention and treatment of ER- breast cancer. The NF-κB signaling pathway is strongly implicated in ER- tumor genesis, constituting a possible target for treatment. Hydrogen sulfide-releasing aspirin (HS-ASA), a novel and safer derivative of aspirin, has shown promise as an anti-cancer agent. We examined the growth inhibitory effect of HS-ASA via alterations in cell proliferation, cell cycle phase transitions, and apoptosis, using MDA-MB-231 cells as a model of triple negative breast cancer. Tumor xenografts in mice, representing human ER- breast cancer, were evaluated for reduction in tumor size, followed by immunohistochemical analysis for proliferation, apoptosis and expression of NF-κB. HS-ASA suppressed the growth of MDA-MB-231 cells by induction of G(0)/G(1) arrest and apoptosis, down-regulation of NF-κB, reduction of thioredoxin reductase activity, and increased levels reactive oxygen species. Tumor xenografts in mice, were significantly reduced in volume and mass by HS-ASA treatment. The decrease in tumor mass was associated with inhibition of cell proliferation, induction of apoptosis and decrease in NF-κB levels in vivo. HS-ASA has anti-cancer potential against ER- breast cancer and merits further study.

MEK5/ERK5 pathway: the first fifteen years

While conventional MAP kinase pathways are one of the most highly studied signal transduction molecules, less is known about the MEK5 signaling pathway. This pathway has been shown to play a role in normal cell growth cycles, survival and differentiation. The MEK5 pathway is also believed to mediate the effects of a number of oncogenes. MEK5 is the upstream activator of ERK5 in many epithelial cells. Activation of the MEK-MAPK pathway is a frequent event in malignant tumor formation and contributes to chemoresistance and anti-apoptotic signaling. This pathway may be involved in a number of more aggressive, metastatic varieties of cancer due to its role in cell survival, proliferation and EMT transitioning. Further study of this pathway may lead to new prognostic factors and new drug targets to combat more aggressive forms of cancer.

Targeting NFĸB mediated breast cancer chemoresistance through selective inhibition of sphingosine kinase-2

Resistance to chemotherapy remains a significant obstacle in the treatment of hormone- independent breast cancer. Recent evidence suggests that altered sphingolipid signaling through increased sphingosine kinase activity may be an important mediator of breast cancer drug resistance. Sphingosine kinase-1 (Sphk1) is a proposed key regulator of breast cancer tumorigenesis, proliferation and resistance. There is, however, conflicting data on the role of sphingosine kinase-2 (Sphk2) in cancer biology and resistance, with some suggesting that Sphk2 has an opposing role to that of Sphk1. Here, we studied the effects of the novel selective Sphk2 inhibitor, ABC294640 (3-(4-chlorophenyl)-adamantane-1-carboxylic acid (pyridin-4-ylmethyl) amide), on human breast cancer. ABC294640 blocked both viability and survival at low micromolar IC(50) concentrations in the endocrine therapy-resistant MDA-MB-231 and chemoresistant MCF-7TN-R cell systems. Treatment with the inhibitor significantly reduced proliferation, as seen in immunofluorescence staining of Ki-67 in vitro. Interestingly, pharmacological inhibition of Sphk2 induced apoptosis through the intrinsic programmed cell death pathway. Furthermore, ABC294640 also diminished NF-ĸB survival signaling, through decreased activation of the Ser536 phosphorylation site on the p65 subunit. Xenografts of MCF-7TN-R cells growing in immunocompromised mice were utilized to validate the therapeutic efficacy of the sphingosine kinase-2 inhibitor. Treatment with 50 mg of ABC294640/kg completely blocked tumor volume in this model. These results indicate that pharmacological inhibition of Sphk2 with the orally bioavailable selective inhibitor, ABC294640, has therapeutic potential in the treatment of chemo- and endocrine therapy- resistant breast cancer.

Resveratrol confers resistance against taxol via induction of cell cycle arrest in human cancer cell lines

Resveratrol, which is highly concentrated in the skin of grapes and is abundant in red wine, has been demonstrated to account for several beneficial properties, including antioxidant, anticoagulant, anti-inflammatory and anticancer effects. Taxol is a microtubule-stabilizing drug that has been extensively used as effective chemotherapeutic agents in the treatment of solid tumors. Here, we investigated whether the combination of the two compounds would yield increased antitumor efficacy in human cancer cells. Unexpectedly, resveratrol effectively prevented tumor cell death induced by taxol in 5637 bladder cancer cells. This pronounced antagonistic function of resveratrol against taxol was associated with changes in multiple signal transduction pathways, but not with tubulin polymerization. Importantly, cell cycle analysis showed that resveratrol prevented the cells from entering into mitosis, the phase in which taxol exerts its action. Furthermore, resveratrol blocked the cytotoxic effects of vinblastine but not cisplatin in 5637 cells. Interestingly, resveratrol pre-treatment followed by taxol resulted in synergistic cytotoxicity. Finally, we extended our studies to various human cancer cell lines. Taken together, our results indicate that resveratrol may have the potential to negate the therapeutic efficacy of taxol and suggest that consumption of resveratrol-related products may be contraindicated during cancer therapy with taxol.

Development of cell-based high-throughput assays for the identification of inhibitors of receptor activator of nuclear factor-kappa B signaling

Bone loss due to metabolic or hormonal disorders and osteolytic tumor metastasis continues to be a costly health problem, but current therapeutics offer only modest efficacy. Unraveling of the critical role for the receptor activator of nuclear factor-kappa B (RANK) and its ligand, RANK ligand (RANKL), in osteoclast biology provides an opportunity to develop more effective antiresorptive drugs. The in vivo effectiveness of RANKL inhibitors demonstrates the potency of the RANKL/RANK system as a drug target. Here, we report the development of cell-based assays for high-throughput screening to identify compounds that inhibit signaling from two RANK cytoplasmic motifs (PVQEET(559-564) and PVQEQG(604-609)), which play potent roles in osteoclast formation and function. Inhibitors of these motifs' signaling have the potential to be developed into new antiresorptive drugs that can complement current therapies. The cell-based assays consist of cell lines generated from RAW264.7 macrophages stably expressing a nuclear factor-kappa B-responsive luciferase reporter and a chimeric receptor containing the human Fas external domain linked to a murine RANK transmembrane and intracellular domain in which only one of the RANK motifs is functional. With these cells, specific RANK motif activation after chimeric receptor stimulation can be measured as an increase in luciferase activity. These assays demonstrated >300% increases in luciferase activity after RANK motif activation and Z '-factor values over 0.55. Our assays will be used to screen compound libraries for molecules that exhibit inhibitory activity. Follow-up assays will refine hits to a smaller group of more specific inhibitors of RANK signaling.

Antiestrogenic effects of the novel sphingosine kinase-2 inhibitor ABC294640

Alterations in sphingolipid metabolism have been shown to contribute to the development of endocrine resistance and breast cancer tumor survival. Sphingosine kinase (SK), in particular, is overexpressed in breast cancer and is a promising target for breast cancer drug development. In this study, we used the novel SK inhibitor ABC294640 as a tool to explore the relationship between SK and estrogen (E2) receptor (ER) signaling in breast cancer cells. Treatment with ABC294640 decreased E2-stimulated ERE-luciferase activity in both MCF-7 and ER-transfected HEK293 cells. Furthermore, the inhibitor reduced E2-mediated transcription of the ER-regulated genes progesterone receptor and SDF-1. Competitive receptor-binding assays revealed that ABC294640 binds in the antagonist ligand-binding domain of the ER, acting as a partial antagonist similar to tamoxifen. Finally, treatment with ABC294640 inhibited ER-positive breast cancer tumor formation in vivo. After 15 d of treatment with ABC294640, tumor volume was reduced by 68.4% (P < 0.05; n = 5) compared with control tumors, with no marked weight loss or illness. Taken together, these results provide strong evidence that this novel SK inhibitor, which had not previously been known to interact with E2 signaling pathways, has therapeutic potential in treating ER-positive breast cancer via inhibition of both SK and ER signaling.

Obovatol enhances docetaxel-induced prostate and colon cancer cell death through inactivation of nuclear transcription factor-kappaB

Nuclear transcription factor-kappaB (NF-kappaB) is constitutively activated in prostate and colon cancers and is related with the resistance of cancer cells against chemotherapeutics. Previously, we found that obovatol, an active compound isolated from Magnolia obovata, inhibited cancer cell growth through inhibition of NF-kappaB activity. We investigated here whether obovatol could sensitize cancer cells against docetaxel through inhibition of NF-kappaB activity in prostate cancer (LNCaP and PC-3) and colon cancer (SW620 and HCT116) cells. The combination treatment with each drug at one half the respective IC(50) dose (5 microM obovatol + 5 nM docetaxel) was more effective and significant (60%-70%) in the inhibition of cancer cell growth than single treatment by each drug (20%-40%); inhibition was exerted through a significant increase of apoptosis induction (60%-80%) by the combination treatment compared to the single treatment (10%-30%). Correlating well with the synergistic inhibition (combination indices are less than 1 in all cell types), the combination significantly inhibited NF-kappaB activities as well as expression of NF-kappaB target apoptotic cell death proteins, but decreased anti-apoptotic cell death proteins. Similar combination effects of obovatol with other chemotherapeutic agents (paclitaxel, cisplatin, and doxorubicin) on the inhibition of cell growth and NF-kappaB activity were also found. These results indicate that obovatol augments cell growth inhibition by chemotherapeutics through inactivation of NF-kappaB and suggest that obovatol may have therapeutic advantages in the combination treatment with other chemotherapeutics. [Supplementary Figure: available only at http://dx.doi.org/10.1254/jphs.09048FP].

Combination of ginsenoside Rg3 with docetaxel enhances the susceptibility of prostate cancer cells via inhibition of NF-kappaB

Ginsenoside Rg3 has been a subject of interest for use as a cancer preventive or therapeutic agent. Nuclear factor-kappa (NF-kappaB) is constitutively activated in prostate cancer, and gives cancer cells resistance to chemotherapeutic agents. To investigate whether Rg3 can suppress the activation of NF-kappaB, and thus increase susceptibility of prostate (LNCaP and PC-3, DU145) cells against chemotherapeutics, prostate cancer cell growth as well as activation of NF-kappaB was examined. We found that a combination treatment of Rg3 (50 microM) with a conventional agent docetaxel (5 nM) was more effective in the inhibition of prostate cancer cell growth and induction of apoptosis as well as G(0)/G(1) arrest accompanied with the significant inhibition of NF-kappaB activity than those by treatment of Rg3 or docetaxel alone. It was also found that NF-kappaB target gene expression of Bax, caspase-3, and caspase-9 was much more significantly enhanced, but the expression of Bcl-2, inhibitor of apoptosis protein (IAP-1) and X chromosome IAP (XIAP), and the expression of cell cycle regulatory proteins cyclin B, D1 and E, and cyclin dependent kinases 2 and 4 was also much more significantly inhibited by the combination treatment. The combination of Rg3 (50 microM) with cisplatin (10 microM) and doxorubicin (2 microM) was also more effective in the inhibition of prostate cancer cell growth and NF-kappaB activity than those by the treatment of Rg3 or chemotherapeutics alone. These results indicate that ginsenoside Rg3 inhibits NF-kappaB, and enhances the susceptibility of prostate cancer cells to docetaxel and other chemotherapeutics. Thus, ginsenoside Rg3 could be useful as an anti-cancer agent.

Obesity and breast cancer: the roles of peroxisome proliferator-activated receptor-γ and plasminogen activator inhibitor-1

Breast cancer is the most prominent cancer among females in the United States. There are a number of risk factors associated with development of breast cancer, including consumption of a high-fat diet and obesity. Plasminogen activator inhibitor-1 (PAI-1) is a cytokine upregulated in obesity whose expression is correlated with a poor prognosis in breast cancer. As a key mediator of adipogenesis and regulator of adipokine production, peroxisome proliferator-activated receptor-γ (PPAR-γ) is involved in PAI-1 expression from adipose tissue. We summarize the current knowledge linking PPAR-γ and PAI-1 expression to high-fat diet and obesity in the risk of breast cancer.

Sphingolipids as determinants of apoptosis and chemoresistance in the MCF-7 cell model system

An estimated 182,640 women and 1,990 men were diagnosed with breast cancer in 2008, and approximately 40,480 women and 450 men died from the disease. Thus, continued mechanistic studies are needed to understand the causes and develop additional therapeutics for this complicated disease. The MCF-7 cell system is one of the most recognized models for estrogen receptor (ER)-positive breast cancer and has generated approximately 13,000 publications cited in PubMed to date. A number of clues for biological mechanisms related to apoptotic/anti-apoptotic pathways and chemoresistance were elucidated and summarized in our previous review. The focus of this review is new knowledge of the central role of sphingolipid signaling in apoptotic mechanisms in estrogen receptor-positive breast cancer. The ultimate goal is to target crucial steps in survival signaling pathways that may ultimately provide additional translational solutions to the successful pharmacologic treatment of breast cancer.

Inhibition of NF-kappaB by ginsenoside Rg3 enhances the susceptibility of colon cancer cells to docetaxel

Ginsenoside Rg3, the main constituent isolated from Panax ginseng, has been of interest for use as a cancer preventive or therapeutic agent. We investigated here whether Rg3 can inhibit the activity of NF-kappaB, a key transcriptional factor constitutively activated in colon cancer that confers cancer cell resistance to chemotherapeutic agents. To investigate whether RG3 can suppress activation of NF-kappaB, and thus inhibit cancer cell growth, we examined the susceptibility of colon cancer cells (SW620 and HCT116) to treatment with Rg3 (25, 50, 75, 100 microM) and RG3-induced activation of NF-kappaB. RG3 dose-dependently inhibited cancer cell growth through induction of apoptosis and decreased NF-kappaB activity. In a further study of compounds in colon cancer, we used half of the IC(50) dose, values in combined treatments of Rg3 (50 microM) with conventional agents - docetaxel (5 nM), paclitaxel (10 nM) cisplatin (10 microM) and doxorubicin (2 microM). Compared to treatment with Rg3 or chemotherapy alone, combined treatment was more effective (i.e., there were synergistic effects) in the inhibition of cancer cell growth and induction of apoptosis and these effects were accompanied by significant inhibition of NF-kappaB activity. NF-kappaB target gene expression of apoptotic cell death proteins (Bax, caspase-3, caspase-9) was significantly enhanced, but the expression of anti-apoptotic genes and cell proliferation marker genes (Bcl-2, inhibitor of apoptosis protein (IAP-1) and X chromosome IAP (XIAP), Cox-2, c-Fos, c-Jun and cyclin D1) was significantly inhibited by the combined treatment compared to Rg3 or docetaxel alone. These results indicate that ginsenoside Rg3 inhibits NF-kappaB, and enhances the susceptibility of colon cancer cells to docetaxel and other chemotherapeutics. Thus, ginsenoside Rg3 could be useful as an anti-cancer or adjuvant anti-cancer agent.

A phase I study of full-dose gemcitabine and regional arterial infusion of nafamostat mesilate for advanced pancreatic cancer

BACKGROUND

The primary end points of this study were to determine the dose-limiting toxic effects (DLTs), maximum tolerated dose, and a recommended phase II dose of a synthetic serine protease inhibitor, nafamostat mesilate, in combination with full-dose gemcitabine in patients with unresectable locally advanced or metastatic pancreatic cancer. The secondary end point was to assess therapeutic response.

PATIENTS AND METHODS

Patients with previously untreated pancreatic cancer received gemcitabine (1 000 mg/m(2) i.v. for 30 min) on days 1, 8, and 15, with nafamostat mesilate (continuous regional arterial infusion for 24 h through a port-catheter system) on days 1, 8, and 15; this regimen was repeated at 28-day intervals. The initial dose of nafamostat mesilate was 2.4 mg/kg and was escalated in increments of 1.2 mg/kg until a dose of 4.8 mg/kg was achieved. A standard '3+3' phase I dose-escalation design was used. Therapeutic response and clinical benefit response were assessed.

RESULTS

Twelve patients were enrolled in this study. None of the patients experienced DLTs, and nafamostat mesilate was well tolerated at doses up to 4.8 mg/kg in combination with full-dose gemcitabine. This combination chemotherapy yielded a reduction of a high serum level of the tumor marker CA19-9. Pain was reduced in three of seven patients without oral morphine sulfate. Overall survival was 7.1 months for all patients.

CONCLUSION

This phase I study was carried out safely. This combination chemotherapy showed beneficial improvement in health-related quality of life. The recommended phase II dose of nafamostat mesilate in combination with full-dose gemcitabine is 4.8 mg/kg.

Acquisition of stable inducible up-regulation of nuclear factor-kappaB by tumor necrosis factor exposure confers increased radiation resistance without increased transformation in breast cancer cells

High-grade breast cancers are better adapted to hypoxia and more resistant to chemotherapy and radiotherapy. Constitutive activation of the transcription factor nuclear factor-kappaB (NF-kappaB) increases in breast tumors and in breast cancer cell lines, where it promotes chemoradiation resistance, in part by activation of antiapoptotic genes. The role for up-regulation of NF-kappaB in breast cancer progression is less clear. Here, we first show that whereas the constitutive activity of NF-kappaB is incrementally elevated from immortalized breast epithelial to frank transformed invasive ductal breast cancer cell lines (~3-fold, +/-0.1-fold, P < 0.05), inflammatory cytokine-inducible activity is further increased (up to 9-fold, +/-0.9-fold, P < 0.05). We then show that inhibition of NF-kappaB activity selectively sensitizes transformed but not immortalized cells to killing by ionizing radiation or low levels of tumor necrosis factor (TNF) by up to 10-fold (+/-1-fold, P < 0.05) but has little effect on hypoxia-mediated cell death. Prolonged cultivation of immortalized and partially transformed cells in TNF selected for cells displaying stable constitutive and strongly inducible overexpression of NF-kappaB even in the absence of TNF. Stable acquisition of increased NF-kappaB activity conferred resistance to ionizing radiation or inflammatory cytokines, which was dependent on elevated NF-kappaB activity, but had no effect on transformation potential measured by in vitro and in vivo parameters. Thus, TNF and possibly other inflammatory cytokines in the tumor-stroma matrix likely select for breast cancer cells that stably overexpress NF-kappaB, leading to greater cancer cell survival. Greater cell survival despite increased genomic injury may permit increased acquisition of malignant genetic alterations as well as resistance to chemoradiation therapy.

Nitrosylcobalamin potentiates the anti-neoplastic effects of chemotherapeutic agents via suppression of survival signaling

BACKGROUND

Nitrosylcobalamin (NO-Cbl) is a chemotherapeutic pro-drug derived from vitamin B12 that preferentially delivers nitric oxide (NO) to tumor cells, based upon increased receptor expression. NO-Cbl induces Apo2L/TRAIL-mediated apoptosis and inhibits survival signaling in a variety of malignant cell lines. Chemotherapeutic agents often simultaneously induce an apoptotic signal and activation of NF-kappaB, which has the undesired effect of promoting cell survival. The specific aims of this study were to 1) measure the anti-tumor effects of NO-Cbl alone and in combination with conventional chemotherapeutic agents, and to 2) examine the mechanism of action of NO-Cbl as a single agent and in combination therapy.

METHODOLOGY

Using anti-proliferative assays, electrophoretic mobility shift assay (EMSA), immunoblot analysis and kinase assays, we demonstrate an increase in the effectiveness of chemotherapeutic agents in combination with NO-Cbl as a result of suppressed NF-kappaB activation.

RESULTS

Eighteen chemotherapeutic agents were tested in combination with NO-Cbl, in thirteen malignant cell lines, resulting in a synergistic anti-proliferative effect in 78% of the combinations tested. NO-Cbl pre-treatment resulted in decreased NF-kappaB DNA binding activity, inhibition of IkappaB kinase (IKK) enzymatic activity, decreased AKT activation, increased caspase-8 and PARP cleavage, and decreased cellular XIAP protein levels.

CONCLUSION

The use of NO-Cbl to inhibit survival signaling may enhance drug efficacy by preventing concomitant activation of NF-kappaB or AKT.

Inositol Hexaphosphate and Paclitaxel: Symbiotic Treatment of Oral Cavity Squamous Cell Carcinoma

OBJECTIVES/HYPOTHESIS

Nuclear factor (NF)-kappaB is an early response gene that has been associated with head and neck squamous cell cancer (HNSCC) progression. NF-kappaB activation is induced by some chemotherapy agents, including paclitaxel. The activation of this gene can be correlated with apoptosis resistance. Inositol hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate. NF-kappaB levels were evaluated in oral cavity HNSCC lines after treatment with paclitaxel and IP6, alone and in combination. Resulting levels of cell death and apoptosis were assessed, and conclusions are drawn regarding a possible synergistic relationship between paclitaxel and IP6.

METHODS

NF-kappaB activation in cancer cells treated with paclitaxel and IP6, alone and in combination, was measured by transient transfection, and results were interpreted by luminometry. Cell proliferation of treated cells was measured by MTT assay. Cell viability and apoptosis of cancer cells treated with paclitaxel and IP6 combinations were quantitated by trypan blue staining and Caspase-Glo 3/7 assay, respectively.

RESULTS

IP6 was observed to significantly downregulate NF-kappaB activation in both NA and CA-9-22 oral cavity HNSCC cell lines. Paclitaxel treatments caused increased NF-kappaB activation in the same cell lines. IP6 was observed to mitigate paclitaxel-induced NF-kappaB activation in the CA-9-22 cell line. IP6, when combined with paclitaxel, reduces CA-9-22 cell proliferation, increases cell death, and increases apoptosis, when compared with treatment with paclitaxel alone.

CONCLUSIONS

IP6 reduces paclitaxel induced NF-kappaB activation and increases paclitaxel-mediated cell killing and apoptosis. As a well-tolerated and safe supplement, IP6 deserves further study in the treatment of oral cavity squamous cell carcinoma.

Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy

NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.

Induction of apoptosis in estrogen receptor-negative breast cancer cells by natural and synthetic cyclopentenones: role of the IkappaB kinase/nuclear factor-kappaB pathway

Nuclear factor-kappaB (NF-kappaB), a transcription factor with a critical role in promoting inflammation and cell survival, is constitutively activated in estrogen-receptor (ER)-negative breast cancer and is considered a potential therapeutic target for this type of neoplasia. We have previously demonstrated that cyclopentenone prostaglandins are potent inhibitors of NF-kappaB activation by inflammatory cytokines, mitogens, and viral infection, via direct binding and modification of the beta subunit of the IkappaB kinase complex (IKK). Herein, we describe the NF-kappaB-dependent anticancer activity of natural and synthetic cyclopentenone IKK inhibitors. We demonstrate that the natural cyclopentenone 15-deoxy-Delta(12,14)prostaglandin J(2) (15d-PGJ(2)) is a potent inhibitor of constitutive IkappaB-kinase and NF-kappaB activities in chemotherapy-resistant ER-negative breast cancer cells. 15d-PGJ(2)-induced inhibition of NF-kappaB function is rapidly followed by down-regulation of NF-kappaB-dependent antiapoptotic proteins cIAPs 1/2, Bcl-X(L), and cellular FLICE-inhibitory protein, leading to caspase activation and induction of apoptosis in breast cancer cells resistant to treatment with paclitaxel and doxorubicin. We then demonstrate that the cyclopentenone ring structure is responsible for these activities, and we identify a new synthetic cyclopentenone derivative, 3-tert-butyldimethylsilyloxy-5-(E)-iso-propylmethylenecyclopent-2-enone (CTC-35), as a potent NF-kappaB inhibitor with proapoptotic activity in ER-negative breast cancer cells. The results open new perspectives in the search for novel proapoptotic molecules effective in the treatment of cancers presenting aberrant NF-kappaB regulation.

Assessment of tumor necrosis factor alpha blockade as an intervention to improve tolerability of dose-intensive chemotherapy in cancer patients

PURPOSE

Maintaining dose-intensity with chemotherapeutic agents is hindered by a number of adverse effects including asthenia/fatigue. Tumor necrosis factor (TNF) is one of the cytokines responsible for the fatigue and cachexia associated with malignancies. We used etanercept (TNF-decoy receptor) to maintain dose-intensity of weekly docetaxel.

PATIENTS AND METHODS

Initially, 12 patients with advanced malignancies were randomly assigned to either docetaxel 43 mg/m2 weekly alone (cohort A) or the same docetaxel dose plus etanercept 25 mg subcutaneously twice weekly (cohort B). Subsequently, higher doses of docetaxel in combination with etanercept were evaluated. Pharmacokinetics (PKs), nuclear factor-kappa B (NF-kappaB) activation, and intracellular cytokines levels were measured. Patients completed weekly questionnaires quantifying asthenia/fatigue.

RESULTS

Twenty-nine of 36 intended docetaxel doses during the first cycle were delivered in cohort A, and 35 of 36 doses were delivered in cohort B (P = .055). Three cohort B patients received additional cycles in the absence of disease progression or severe toxicity, whereas no patients from cohort A received additional cycles. Escalation to docetaxel 52 mg/m2 weekly with etanercept resulted in neutropenia, not fatigue, as the limiting adverse effect, and the addition of filgrastim permitted the maintenance of dose-intensity in additional patients. Patients randomly selected to receive etanercept/docetaxel self-reported less fatigue (P < .001), and docetaxel PKs show no relevant influence of etanercept. NF-kappaB activation and increased expression of TNF-alpha were associated with increments in docetaxel dose. Antitumor activity was noticed exclusively in patients receiving etanercept.

CONCLUSION

The addition of etanercept is safe and had no impact on docetaxel concentrations. The significant improvement in tolerability and the trend toward preservation of dose-intensity suggests further exploration of TNF blockade as an adjunct to cancer therapies.

Sensitization of tumor cells toward chemotherapy: enhancing the efficacy of camptothecin with imidazolines

Activation of nuclear transcription factor kappaB (NF-kappaB) by chemotherapeutic agents was found to protect cells from apoptosis. In light of its central role in regulating the cellular resistance to apoptotic agents, inhibition of NF-kappaB-mediated gene transcription may sensitize tumor cells to chemotherapeutic agents and enhance their efficacy. We describe herein a noncytotoxic imidazoline scaffold that sensitizes leukemia T cells to the chemotherapeutic agent camptothecin. No significant induction of apoptosis was found when cells were treated with the imidazoline; however, pretreatment of cells with this agent resulted in a drastic enhancement in efficacy of camptothecin (approximately 75-fold). Elucidation of the potential cellular mechanism revealed that the imidazoline prevents nuclear translocation of NF-kappaB. These findings indicate that inhibition of NF-kappaB by this imidazoline may present improved strategies in the chemotherapeutic treatment of cancer.

Apoptosis and production of TNF-alpha by tumor-associated inflammatory cells in histological grade III breast cancer

Tumor necrosis factor alpha (TNF-alpha) is a cytokine that acts as an important mediator of the apoptotic process that also demonstrates selective citotoxicity against malignant breast tumor cells. In the present study, the presence of apoptotic tumor cells and the synthesis of TNF-alpha by inflammatory cells were investigated in tissue samples from grade III invasive breast cancer with long-term follow-up. In situ detection of tumor apoptotic cells was investigated by direct immuno-peroxidase of digoxigenin-labeled genomic DNA. The production of TNF-alpha and tumor cell proliferation were investigated by immunohistochemical procedures. Our data demonstrated that patients with a clinical history of cancer recurrence and metastasis presented a lower number of cancerous apoptotic cells, higher tumor proliferation rates, and lower TNF-alpha expression rates by inflammatory cells than what is observed among patients diagnosed with the same histopathological breast cancer type but in the absence of tumor recurrence and metastasis.

Inhibition of inhibitor of nuclear factor-kappaB phosphorylation increases the efficacy of paclitaxel in in vitro and in vivo ovarian cancer models

We investigated whether inhibition of nuclear factor-kappaB (NFkappaB) increases the efficacy of paclitaxel in in vitro and in vivo ovarian cancer models. Treatment of paclitaxel-sensitive Caov-3 cells with paclitaxel transiently activated the phosphorylation of Akt, the phosphorylation of IkappaB kinase (IKK), and the phosphorylation of inhibitor of NFkappaB (IkappaBalpha). Paclitaxel also caused a transient increase in NFkappaB activity, followed by a decrease in NFkappaB activity. We show an association between Akt and IKK and show that the phosphorylation of IKK induced by paclitaxel is blocked by treatment with a phosphatidylinositol 3-kinase inhibitor (wortmannin or LY294002). Furthermore, interference of the Akt signaling cascade inhibits the transient induction of IkappaBalpha phosphorylation and NFkappaB activity by paclitaxel. Inhibition of NFkappaB activity by treatment with an IkappaBalpha phosphorylation inhibitor (BAY 11-7085) attenuated both basal and transient induction of IkappaBalpha phosphorylation by paclitaxel. Treatment with BAY 11-7085 also enhanced the inhibition of NFkappaB activity by paclitaxel for up to 24 hours. In addition, treatment with BAY 11-7085 decreased the viability of cells treated with paclitaxel. Moreover, treatment with BAY 11-7085 increased the efficacy of paclitaxel-induced inhibition of intraabdominal dissemination and production of ascites in athymic nude mice inoculated intraperitoneally with Caov-3 cells. These results suggest that paclitaxel transiently induces NFkappaB activity via the phosphatidylinositol 3-kinase/Akt cascade and that combination therapy with paclitaxel and an NFkappaB inhibitor would increase the therapeutic efficacy of paclitaxel.

The NF-kappaB/IkappaB signaling system: a molecular target in breast cancer therapy

The nuclear factor kappaB (NFkappaB) superfamily of eukaryotic transcription factors plays an important role in carcinogenesis. NF-kappaB and its regulators are linked to various signal transduction pathways as well as transcriptional activation events that mediate critical stages of cell proliferation. These intracellular signaling processes are thought to regulate chromatin structure to accommodate transcription, apoptosis, cell-cycle control, and cell transformation. In this capacity, uncontrolled or aberrant NF-kappaB activity may, in part, be responsible for breast cancer progression. Constitutive NF-kappaB expression may predict the metastatic potential of breast tumors, indicating early use of adjuvant therapy and suggesting NF-kappaB inhibition as a novel treatment. In this review, we discuss the regulatory mechanisms and physiological significance of NF-kappaB activation, and highlight recent advances in the development of NF-kappaB as an integral mediator of mammary carcinogenesis.

Expression of nuclear factor-kappa B and I kappa B alpha proteins in prostatic adenocarcinomas: correlation of nuclear factor-kappa B immunoreactivity with disease recurrence

PURPOSE

The nuclear transcription factor nuclear factor-kappa B (NF kappa B) and its inhibitor, I kappa B, regulate the transcription of various genes involved in cell proliferation, adhesion, and survival. The NF kappa B transcription factor complex plays a role in cancer development and progression through its influence on apoptosis. More recently, NF kappa B has been shown to be activated in human and androgen-independent prostate cancer cells. To our knowledge, this is the first study demonstrating the prognostic significance of NF kappa B immunoreactivity in prostate adenocarcinomas (PACs).

EXPERIMENTAL DESIGN

Using prostatectomy specimens, we performed immunohistochemical staining for NF kappa B and I kappa B alpha (Santa Cruz Biotechnology) on formalin-fixed, paraffin-embedded sections obtained from 136 patients with PAC. Cytoplasmic and nuclear immunoreactivity was scored for intensity and distribution, and results were correlated with preoperative serum prostate-specific antigen, tumor grade, stage, DNA ploidy (Feulgen spectroscopy), and biochemical disease recurrence.

RESULTS

Forty-nine percent of PACs overexpressed cytoplasmic NF kappa B, and 63% showed decreased I kappa B expression. Cytoplasmic NF kappa B overexpression correlated with advanced tumor stage (P = 0.048), aneuploidy (P = 0.022), and biochemical disease recurrence (P = 0.001). When we compared the means for the NF kappa B-positive and -negative subgroups, NF kappa B overexpression correlated with preoperative serum prostate-specific antigen (P = 0.04) and DNA index (P = 0.05). Fifteen percent of PACs expressed nuclear NF kappa B, which correlated with high tumor grade (P = 0.001) and advanced stage (P = 0.05). Decreased I kappa B alpha expression correlated with high tumor grade (P = 0.015). On multivariate analysis, tumor stage (P = 0.043) and NF kappa B overexpression (P = 0.006) were independent predictors of biochemical recurrence.

CONCLUSION

These results support a role for NF kappa B pathway proteins in the tumorigenesis of PACs. The findings are also consistent with reported experimental studies suggesting a new strategy of combined chemotherapy and specific NF kappa B blockade in decreasing the rate of disease relapse.