In vitro and in vivo sensitization of SW620 metastatic colon cancer cells to CDDP-induced apoptosis by the nitric oxide donor DETANONOate: Involvement of AIF

GTN Enhances Antitumor Effects of Doxorubicin in TNBC by Targeting the Immunosuppressive Activity of PMN-MDSC

(1) Background: Immunosuppression is a key barrier to effective anti-cancer therapies, particularly in triple-negative breast cancer (TNBC), an aggressive and difficult to treat form of breast cancer. We investigated here whether the combination of doxorubicin, a standard chemotherapy in TNBC with glyceryltrinitrate (GTN), a nitric oxide (NO) donor, could overcome chemotherapy resistance and highlight the mechanisms involved in a mouse model of TNBC. (2) Methods: Balb/C-bearing subcutaneous 4T1 (TNBC) tumors were treated with doxorubicin (8 mg/Kg) and GTN (5 mg/kg) and monitored for tumor growth and tumor-infiltrating immune cells. The effect of treatments on MDSCs reprogramming was investigated ex vivo and in vitro. (3) Results: GTN improved the anti-tumor efficacy of doxorubicin in TNBC tumors. This combination increases the intra-tumor recruitment and activation of CD8⁺ lymphocytes and dampens the immunosuppressive function of PMN-MDSCs PD-L1^low. Mechanistically, in PMN-MDSC, the doxorubicin/GTN combination reduced STAT5 phosphorylation, while GTN +/- doxorubicin induced a ROS-dependent cleavage of STAT5 associated with a decrease in FATP2. (4) Conclusion: We have identified a new combination enhancing the immune-mediated anticancer therapy in a TNBC mouse model through the reprograming of PMN-MDSCs towards a less immunosuppressive phenotype. These findings prompt the testing of GTN combined with chemotherapies as an adjuvant in TNBC patients experiencing treatment failure.

Historical Perspectives of the Role of NO/NO Donors in Anti-Tumor Activities: Acknowledging Dr. Keefer's Pioneering Research

The role of nitric oxide (NO) in cancer has been a continuous challenge and particularly the contradictory findings in the literature reporting NO with either anti-cancer properties or pro-cancer properties. This dilemma was largely resolved by the level of NO/inducible nitric oxide synthase in the tumor environment as well as other cancer-associated gene activations in different cancers. The initial findings on the role of NO as an anti-cancer agent was initiated in the late 1990's in Dr. Larry Keefer's laboratory, who had been studying and synthesizing many compounds with releasing NO under different conditions. Using an experimental model with selected NO compounds they demonstrated for the first time that NO can inhibit tumor cell proliferation and sensitizes drug-resistant cancer cells to chemotherapy-induced cytotoxicity. This initial finding was the backbone and the foundation of subsequent reports by the Keefer's laboratory and followed by many others to date on NO-mediated anti-cancer activities and the clinical translation of NO donors in cancer therapy. Our laboratory initiated studies on NO-mediated anti-cancer therapy and chemo-immuno-sensitization following Keefer's findings and used one of his synthesized NO donors, namely, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETANONOate), throughout most of our studies. Many of Keefer's collaborators and other investigators have reported on the selected compound, O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl] diazen-1-ium-1,2-diolate (JS-K), and its therapeutic role in many tumor model systems. Several lines of evidence that investigated the treatment with NO donors in various cancer models revealed that a large number of gene products are modulated by NO, thus emphasizing the pleiotropic effects of NO on cancers and the identification of many targets of therapeutic significance. The present review reports historically of several examples reported in the literature that emanated on NO-mediated anti-cancer activities by the Keefer's laboratory and his collaborators and other investigators including my laboratory at the University of California at Los Angeles.

Chronic nitric oxide exposure induces prostate cell carcinogenesis, involving genetic instability and a pro-tumorigenic secretory phenotype

Prostate cancer is a leading cause of cancer death in men. Inflammation and overexpression of inducible nitric oxide synthase (NOS2) have been implicated in prostate carcinogenesis. We aimed to explore the hypothesis that nitric oxide NO exerts pro-tumorigenic effects on prostate cells at physiologically relevant levels contributing to carcinogenesis. We investigated the impact of acute exposure of normal immortalised prostate cells (RWPE-1) to NO on cell proliferation and activation of DNA damage repair pathways. Furthermore we investigated the long term effects of chronic NO exposure on RWPE-1 cell migration and invasion potential and hallmarks of transformation. Our results demonstrate that NO induces DNA damage as indicated by γH2AX foci and p53 activation resulting in a G1/S phase block and activation of 53BP1 DNA damage repair protein. Long term adaption to NO results in increased migration and invasion potential, acquisition of anchorage independent growth and increased resistance to chemotherapy. This was recapitulated in PC3 and DU145 prostate cancer cells which upon chronic exposure to NO displayed increased cell migration, colony formation and increased resistance to chemotherapeutics. These findings indicate that NO may play a key role in the development of prostate cancer and the acquisition of an aggressive metastatic phenotype.

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

The metabolic adaptation evoked by arginine enhances the effect of radiation in brain metastases

Selected patients with brain metastases (BM) are candidates for radiotherapy. A lactatogenic metabolism, common in BM, has been associated with radioresistance. We demonstrated that BM express nitric oxide (NO) synthase 2 and that administration of its substrate l-arginine decreases tumor lactate in BM patients. In a placebo-controlled trial, we showed that administration of l-arginine before each fraction enhanced the effect of radiation, improving the control of BM. Studies in preclinical models demonstrated that l-arginine radiosensitization is a NO-mediated mechanism secondary to the metabolic adaptation induced in cancer cells. We showed that the decrease in tumor lactate was a consequence of reduced glycolysis that also impacted ATP and NAD⁺ levels. These effects were associated with NO-dependent inhibition of GAPDH and hyperactivation of PARP upon nitrosative DNA damage. These metabolic changes ultimately impaired the repair of DNA damage induced by radiation in cancer cells while greatly sparing tumor-infiltrating lymphocytes.

Evaluation of a Synergistic Effect of L-Arginine on the Anticancer Activity of Doxorubicin by Using a Co-culture System

In the early stage of tumor development, tumor-associated macrophages (TAM) works to suppress tumor growth by secreting soluble factors including nitric oxide (NO). L-Arginine (Arg) is a substrate of nitric oxide synthase (NOS) expressed in TAM. Here we examined whether NO produced from Arg by macrophages works to enhance the effect of the anti-cancer drug, doxorubicin (Dox) by using a co-culture system of cancer cells with macrophages. By employing colorimetric analyses methods (Griess Reagent and Cell Counting kit-8), we found that NO produced from Arg by co-cultured macrophages could enhance the cytotoxic effect of Dox to cancer cells. Moreover, we found that augmentation is affected by the order of the addition of Arg and Dox. A prior addition of Arg to Dox and simultaneous addition showed the same enhancement effect, but a prior addition of Dox to Arg abolished the augmentation. This suggests that the co-administration of Arg with Dox would be an effective treatment to improve chemo-therapies.

Sensitizing activities of nitric oxide donors for cancer resistance to anticancer therapeutic drugs

Cancer is not a single disease but it constitutes a large variety of different types that are also different from each other phenotypically and molecularly. Although the standard treatments have resulted in clinical responses in a subset of patients, though, many patients relapse and no longer respond to further treatments. Hence, both the innate and adaptive resistance to treatments are the main challenges in today's treatment strategies. Noteworthy, several novel treatment strategies, particularly immunotherapies, used alone or in combination, have been developed and that have significantly improved the therapeutic response of many unresponsive cancer patients. Nevertheless, even with the latest new developments of therapeutics that were effective in a larger subset of patients, there is still an urgent need to treat the remaining unresponsive subset of patients. This requires the development of new targeting agents of superior antitumor activities that will lead to overcoming the unaffected resistance by current treatments. There has been accumulating evidence suggesting nitric oxide donors as such targeting agents and considering their pleiotropic antitumor activities, including both the reversal of chemo and immuno-resistance of various unresponsive resistant cancers. The in vitro and in vivo preclinical findings corroborate the sensitizing antitumor activities of nitric oxide donors. In addition, a few clinical findings with NO donors that have been applied in patients have corroborated their antitumor and sensitizing activities in combination with standard therapies. In this review, the role and underlying mechanisms by which nitric oxide donors sensitize cancer resistant cells to both chemotherapy and immunotherapy are briefly described.

Quiescent hepatic stellate cells induce toxicity and sensitivity to doxorubicin in cancer cells through a caspase-independent cell death pathway: Central role of apoptosis-inducing factor

Hepatocellular carcinoma (HCC) is a major health problem worldwide and in the United States as its incidence has increased substantially within the past two decades. HCC therapy remains a challenge, primarily due to underlying liver disorders such as cirrhosis that determines treatment approach and efficacy. Activated hepatic stellate cells (A-HSCs) are the key cell types involved in hepatic fibrosis/cirrhosis. A-HSCs are important constituents of HCC tumor microenvironment (TME) and support tumor growth, chemotherapy resistance, cancer cell migration, and escaping immune surveillance. This makes A-HSCs an important therapeutic target in hepatic fibrosis/cirrhosis as well as in HCC. Although many studies have reported the role of A-HSCs in cancer generation and investigated the therapeutic potential of A-HSCs reversion in cancer arrest, not much is known about inactivated or quiescent HSCs (Q-HSCs) in cancer growth or arrest. Here we report that Q-HSCs resist cancer cell growth by inducing cytotoxicity and enhancing chemotherapy sensitivity. We observed that the conditioned media from Q-HSCs (Q-HSCCM) induces cancer cell death through a caspase-independent mechanism that involves an increase in apoptosis-inducing factor expression, nuclear localization, DNA fragmentation, and cell death. We further observed that Q-HSCCM enhanced the efficiency of doxorubicin, as measured by cell viability assay. Exosomes present in the conditioned media were not involved in the mechanism, which suggests the role of other factors (proteins, metabolites, or microRNA) secreted by the cells. Identification and characterization of these factors are important in the development of effective HCC therapy.

Glyceryl trinitrate‑induced cytotoxicity of docetaxel‑resistant prostatic cancer cells is associated with differential regulation of clusterin

Metastatic castration resistant prostate cancer (mCRPC) relapse due to acquired resistance to chemotherapy, such as docetaxel, remains a major threat to patient survival. Resistance of mCRPC to docetaxel can be associated with elevated levels of soluble clusterin (sCLU) and growth differentiation factor‑15 (GDF‑15). Any strategies aiming to modulate sCLU and/or GDF‑15 in docetaxel‑resistant prostate cancer cells present a therapeutic interest. The present study reports the cytotoxic effect of a nitric oxide donor, glyceryl trinitrate (GTN), on docetaxel‑resistant mCRPC human cell lines and demonstrates that GTN displays greater inhibition of cell viability toward docetaxel‑resistant mCRPC cells than on mCRPC cells. It is also demonstrated that GTN modulates the level of expression of clusterin (CLU) which is dependent of GDF‑15, two markers associated with docetaxel resistance in prostate cancer. The results indicate that GTN represses the level of expression of the cytoprotective isoform of CLU (sCLU) and can increase the level of expression of the cytotoxic isoform (nuclear CLU) in docetaxel resistant cells. Furthermore, it was observed that GTN differentially regulates the level of the precursor form of GDF‑15 between resistant and parental cells, and that recombinant GDF‑15 can modulate the expression of CLU isoforms and counteract GTN‑induced cytotoxicity in resistant cells. A link was established between GDF‑15 and the expression of CLU isoforms. The present study thus revealed GTN as a potential therapeutic strategy to overcome docetaxel‑resistant mCRPC.

Hollow S-nitrosothiols nanoparticle with polymeric brushes for nitric oxide (NO)-releasing as tumor targeted chemotherapy

A kind of tumor targeting nitric oxide donor nanoparticle with brushes is described in this paper. The poly(4-vinylphenylboronic acid) polymeric brush, which shows glucose and pH dual responsiveness, endows the ability of hollow S-nitrosothiols nanoparticle to accurate recognition and binding with the sialic acid over-expressed type tumor cells, such as HepG2 and MCF-7 cells. In vitro experiments, including cells capture and release experiments, confocal fluorescence microscope characterization, cytotoxicity assay with different cells, demonstrate the selective recognition and the controlled NO release to kill tumor cells for these S-nitrosothiols nanoparticles. Low concentration of the released NO from the S-nitrosothiols nanoparticles in the transmission would participate physiological activity and avoid serious side effects because the endogenous nature and the physiological necessity to regulate normal biological functions. To the best of our knowledge, this is the first report about polymer nanoparticles as NO donors with functional brushes to selectively identify tumor cells and release NO in a controlled manner.

Inducible Nitric Oxide Synthase in the Carcinogenesis of Gastrointestinal Cancers

SIGNIFICANCE

Gastrointestinal (GI) cancer taken together constitutes one of the most common cancers worldwide with a broad range of etiological mechanisms. In this review, we have examined the impact of nitric oxide (NO) on the etiology of colon, colorectal, gastric, esophageal, and liver cancers. Recent Advances: Despite differences in etiology, initiation, and progression, chronic inflammation has been shown to be a common element within these cancers showing interactions of numerous pathways. NO generated at the inflammatory site contributes to the initiation and progression of disease. The amount of NO generated, time, and site vary and are an important determinant of the biological effects initiated. Among the nitric oxide synthase enzymes, the inducible isoform has the most diverse range, participating in numerous carcinogenic processes. There is emerging evidence showing that inducible nitric oxide synthase (NOS2) plays a central role in the process of tumor initiation and/or development.

CRITICAL ISSUES

Redox inflammation through NOS2 and cyclooxygenase-2 participates in driving the mechanisms of initiation and progression in GI cancers.

FUTURE DIRECTIONS

Understanding the underlying mechanism involved in NOS2 activation can provide new insights into important prevention and treatment strategies. Antioxid. Redox Signal. 26, 1059-1077.

Modulation of the Anti-Tumor Efficacy of Photodynamic Therapy by Nitric Oxide

Nitric oxide (NO) produced by nitric oxide synthase (NOS) enzymes is a free radical molecule involved in a wide variety of normophysiologic and pathophysiologic processes. Included in the latter category are cancer promotion, progression, and resistance to therapeutic intervention. Animal tumor photodynamic therapy (PDT) studies several years ago revealed that endogenous NO can reduce PDT efficacy and that NOS inhibitors can alleviate this. Until relatively recently, little else was known about this anti-PDT effect of NO, including: (a) the underlying mechanisms; (b) type(s) of NOS involved; and (c) whether active NO was generated in vascular cells, tumor cells, or both. In addressing these questions for various cancer cell lines exposed to PDT-like conditions, the author's group has made several novel findings, including: (i) exogenous NO can scavenge lipid-derived free radicals arising from photostress, thereby protecting cells from membrane-damaging chain peroxidation; (ii) cancer cells can upregulate inducible NOS (iNOS) after a PDT-like challenge and the resulting NO can signal for resistance to photokilling; (iii) photostress-surviving cells with elevated iNOS/NO proliferate and migrate/invade more aggressively; and (iv) NO produced by photostress-targeted cells can induce greater aggressiveness in non-targeted bystander cells. In this article, the author briefly discusses these various means by which NO can interfere with PDT and how this may be mitigated by use of NOS inhibitors as PDT adjuvants.

[NO and cancer: itinerary of a double agent]

Protein S-nitrosylation is now recognized as a ubiquitous regulatory mechanism. Like any post-translational modifications, S-nitrosylation is critical for the control of numerous cellular processes. It is now clear that S-nitrosylation is playing a double game, enhancing or inhibiting the tumor growth or the induction of cell death. Thanks to research aimed at demonstrating NO cytotoxic effects, new therapeutic strategies based on NO donor drugs have emerged. Although therapeutic NO donors can target a large number of proteins, the cellular mechanism is still not fully understood. This review reflects the current state of knowledge on S-nitrosylated proteins that take part of the oncogenic and apoptotic signaling, putting forward proteins with potential interest in cancer therapy.

Complex Behavior of ALDH1A1 and IGFBP1 in Liver Metastasis from a Colorectal Cancer

Using our data set (GSE50760) previously established by RNA sequencing, the present study aimed to identify upregulated genes associated with colorectal cancer (CRC) liver metastasis (CLM) and verify their biological behavior. The potential roles of candidate genes in tumors were assessed using cell proliferation and invasion assays. Tissue samples were collected from 18 CRC patients with synchronous CLM and two CRC cell lines (SW480 and SW620) were used for transfection and cloning. The roles of the genes identified in CLM were verified using immunohistochemistry in 48 nude mice after intrasplenic transplantation of CRC cells. mRNA and protein expression was determined by quantitative real-time reverse transcription polymerase chain reaction and western blot, respectively. Nine genes were initially selected according to the relevance of their molecular function and biological process and, finally, ALDH1A1 and IGFBP1 were chosen based on differential mRNA expression and a positive correlation with protein expression. The overexpression of ALDH1A1 and IGFBP1 significantly and time-dependently decreased cell proliferation (p ≤ 0.001–0.003) and suppressed invasiveness by ≥3-fold over control cells (p < 0.001) in the SW480 cell line, whereas they had a slight effect on reducing SW620 cell proliferation. The protein expression levels of E-cadherin, N-cadherin, claudin-1, and vimentin were significantly higher in CLM than in primary tumor tissues (p < 0.05). However, the cadherin switch, namely, N-cadherin overexpression with reduced E-cadherin expression, was not observed in CLM tissues and transfected CRC cells. Irrespective of reduced proliferation and invasion found on in vitro cell assays, persistent overexpression of β-catenin, vimentin, and ZO-1 in IGFBP1-overexpressing SW480 cells possibly contributed to CLM development in mice implanted with IGFBP1-overexpressing SW480 cells (CLM occurrences: SW480/IGFBP1-transfected mice vs. SW480/vector- and SW480/ALDH1A1-transfected mice, 4/8 vs. 0/10, p = 0.023). In conclusion, ALDH1A1 and IGFBP1 are differentially overexpressed in CLM and may play a dual role, functioning as both tumor suppressors and metastasis promoters in CRC.

Design, synthesis, and in vivo evaluations of benzyl Nω-nitro-Nα-(9H-pyrido[3,4-b]indole-3-carbonyl)-l-argininate as an apoptosis inducer capable of decreasing the serum concentration of P-selectin

A series of findings suggest that the discovery of in vivo apoptosis inducers for chemotherapy is of clinical importance.

Nitric oxide- and cisplatin-releasing silica nanoparticles for use against non-small cell lung cancer

Nitric oxide (NO) and cisplatin releasing wrinkle-structured amine-modified mesoporous silica (AMS) nanoparticles have been developed for the treatment of non-small cell lung cancer (NSCLC). The AMS and NO- and cisplatin-loaded AMS materials were characterized using TEM, BET surface area, FTIR and ICP-MS, and tested in cell culture. The results show that for NSCLC cell lines (i.e., H596 and A549), the toxicity of NO- and cisplatin-loaded silica nanoparticles (NO-Si-DETA-cisplatin-AMS) is significantly higher than that of silica nanoparticles loaded with only cisplatin (Si-DETA-cisplatin-AMS). In contrast, the toxicity of NO-Si-DETA-cisplatin-AMS toward normal lung cell lines is not significantly different from that of Si-DETA-cisplatin-AMS (normal lung fibroblast cells WI-38) or is even lower than that of Si-DETA-cisplatin-AMS (normal lung epithelial cells BEAS-2B). The NO-induced sensitization of tumor cell death demonstrates that NO is a promising enhancer of platinum-based lung cancer therapy.

Nitric oxide-mediated sensitization of resistant tumor cells to apoptosis by chemo-immunotherapeutics

The generation of NO by the various NO synthases in normal and malignant tissues is manifested by various biological effects that are involved in the regulation of cell survival, differentiation and cell death. The role of NO in the cytotoxic immune response was first revealed by demonstrating the induction of iNOS in target cells by immune cytokines (e.g. IFN-γ, IL-1, TNF-α, etc.) and resulting in the sensitization of resistant tumor cells to death ligands-induced apoptosis. Endogenous/exogenous NO mediated its immune sensitizing effect by inhibiting NF-κΒ activity and downstream, inactivating the repressor transcription factor YY1, which inhibited both Fas and DR5 expressions. In addition, NO-mediated inhibition of NF-κΒ activity and inhibition downstream of its anti-apoptotic gene targets sensitized the tumor cells to apoptosis by chemotherapeutic drugs. We have identified in tumor cells a dysregulated pro-survival/anti-apoptotic loop consisting of NF-κB/Snail/YY1/RKIP/PTEN and its modification by NO was responsible, in large, for the reversal of chemo and immune resistance and sensitization to apoptotic mechanisms by cytotoxic agents. Moreover, tumor cells treated with exogenous NO donors resulted in the inhibition of NF-κΒ activity via S-nitrosylation of p50 and p65, inhibition of Snail (NF-κΒ target gene), inhibition of transcription repression by S-nitrosylation of YY1 and subsequent inhibition of epithelial-mesenchymal transition (EMT), induction of RKIP (inhibition of the transcription repressor Snail), and induction of PTEN (inhibition of the repressors Snail and YY1). Further, each gene product modified by NO in the loop was involved in chemo-immunosensitization. These above findings demonstrated that NO donors interference in the regulatory circuitry result in chemo-immunosensitization and inhibition of EMT. Overall, these observations suggest the potential anti-tumor therapeutic effect of NO donors in combination with subtoxic chemo-immuno drugs. This combination acts on multiple facets including reversal of chemo-immune resistance, and inhibition of both EMT and metastasis.

Nitric oxide for cancer therapy

Resistance to current therapeutic interventions is a major challenge in the treatment of patients affected by cancer. While nitric oxide (NO) might have proneoplastic properties, it is now clear that at high doses, NO has a role in cancer therapeutics. Either as a single agent or in combination with other antineoplastic compounds, NO might be used to overcome tumor cell resistance to conventional treatments. The following discussion addresses the role of NO in cancer therapeutics and includes a report on the role of NO donors in the area of cancer therapeutics.

Phase I dose escalation trial of nitroglycerin in addition to 5-fluorouracil and radiation therapy for neoadjuvant treatment of operable rectal cancer

BACKGROUND

Nitric oxide donors decreased cell survival in vitro and tumor load in vivo in models of rectal cancer subjected to ionizing radiation. Nitroglycerin (NTG) transdermal patches, added to chemotherapy, have been shown to improve outcomes in lung cancer patients.

METHODS

This open-label, nonrandomized, multicohort, dose escalation, phase I trial had a primary endpoint to evaluate the safety, tolerability, feasibility, dose-limiting toxicity and maximum tolerated dose of topical NTG in addition to 5-fluorouracil and radiation therapy for neoadjuvant treatment of locoregionally advanced operable rectal cancer. The secondary endpoint was rate of pathologic complete response (pCR). Patients were assigned to 3 sequential cohorts of escalating dose levels of commercially available NTG patches (0.2, 0.4, and 0.6 mg/h), each cohort was intended to consist of 3 patients.

RESULTS

Thirteen patients were enrolled in the trial as specified in the dose escalation protocol. They were all male with a median age of 59.4 ± 2.5 (SEM) years. The observed toxicities were mild to moderate and manageable. Four patients developed asymptomatic grade 3 lymphopenia during the chemoradiation that resolved promptly upon completion. One patient had a non-ST segment elevation MI and 1 patient developed diarrhea. None of these toxicities were attributed to NTG except for 1 patient who developed a grade 3 headache. This required an additional group of patients at the same dose and no other patient experienced headaches. pCR was 17%.

CONCLUSION

NTG patches are well-tolerated and it is feasible to proceed with a phase II trial at the maximum dose examined (0.6 mg/h).

The novel heterocyclic trioxirane [(1,3,5-tris oxiran-2-yl)methyl)-1,3,5-triazinane-2,4,6-trione (TATT)] exhibits a better anticancer effect than platinum-based chemotherapy by induction of apoptosis and curcumin further enhances its chemosensitivity

The heterocyclic trioxirane compound [1,3,5-tris((oxiran-2-yl)methyl)-1,3,5-triazinane-2,4,6-trione (TATT)] is a synthetic compound which has been used as an experimental anticancer agent in human clinical trials. Curcumin, an active natural compound in turmeric and curry, is an ingredient commonly used in the traditional diet of many Asian countries. In the present study, we observed that TATT exhibited a better anticancer effect on chemoresistant human colorectal cancer HT-29 cells and displayed less cytotoxicity on normal human umbilical vein endothelial cells, compared with FDA-approved anticancer drugs (cisplatin, carboplatin, or oxaliplatin) using MTT assay. TATT also induced a stronger apoptotic effect than that seen with the three studied anticancer drugs, as characterized by externalization of phosphatidylserine using flow cytometry. Administration of caspase 8-specific inhibitor (z-IETD-fmk) and mitochondrial permeability transition pore inhibitor (cyclosporin A) demonstrated that TATT-induced apoptosis proceeded via both extrinsic and intrinsic signaling pathways. It is noteworthy that coadministration of curcumin further significantly increased TATT-induced cytotoxicity, externalization of phosphatidylserine (representing early apoptosis), and the percentages of cells at the sub-G1 phase (representing late apoptosis), producing an additivity and/or synergistic effect, and vice versa. Suppression of nuclear NF-κB was involved in curcumin-enhanced chemosensitivity of TATT. Overall, our data indicate that TATT exerts a chemotherapeutic effect on colorectal cancer cells and coadministration of curcumin enhances the treatment effect of TATT.

Postulated mechanisms of resistance of B-cell non-Hodgkin lymphoma to rituximab treatment regimens: strategies to overcome resistance

Antibody-mediated immunotherapy has gained significant momentum since 1997 when the US Food and Drug Administration approved the first monoclonal antibody (mAb) for the treatment of B-cell non-Hodgkin lymphoma (B-NHL), namely, rituximab (chimeric anti-CD20 mAb). Subsequently, more than 20 approved mAbs have been in use clinically for the treatment of various cancers and several non-cancer-related diseases. Further, the combination treatment of mAbs with chemotherapy, immunotherapy, proteaosome inhibitors, and other inhibitors has resulted in synergistic anti-tumor activity with significant objective clinical responses. Despite their successful clinical use, the underlying mechanisms of rituximab's in vivo activities remain elusive. Further, it is not clear why a subset of patients is initially unresponsive and many responding patients become refractory and resistant to further treatments; hence, the underlying mechanisms of resistance are not known, Attempts have been made to develop model systems to investigate resistance to mAb therapy with the hope to apply the findings in both the generation of new therapeutics and in their use as new prognostic biomarkers. This review focuses on the development of resistance to rituximab treatments and discusses possible underlying mechanisms of action, postulated mechanisms of resistance in model systems, and suggested means to overcome resistance. Several prior reviews on the subject of rituximab resistance have been published and the present review both complements as well as adds new topics of relevance.

The inhibitory effects of a new cobalt-based polyoxometalate on the growth of human cancer cells

A new cobalt-based polyoxometalate, (Himi)2[Bi(2)W2(0)O(66)(OH)(4)Co2(H2O)(6)Na(4) (H2O)14] · 17H2O (imi = iminazole) (BWCN) has been synthesized and structurally characterized. The inhibitory activities against selected human cancer lines were also determined in this study. The cell viability and chemoresistance of BWCN on human colon carcinoma HT-29 cells were assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide), cell morphology changes, a comet assay and western blot analysis. The typical morphologic changes of apoptosis and DNA damage indicated that BWCN could have a distinct proliferation inhibitory effect on cancer cells. BWCN as a chemotherapeutic agent also induced apoptosis on HT-29 cells and showed a significant expression of cleaved-caspase-3. These results suggested that the active site of BWCN is the polymeric anion based on the basic tectonic block {BiW(9)}, and the possible mechanism is related to the interference of DNA synthesis in cancer cells.

miR-153 supports colorectal cancer progression via pleiotropic effects that enhance invasion and chemotherapeutic resistance

Although microRNAs (miRNA) have been broadly studied in cancer, comparatively less is understood about their role in progression. Here we report that miR-153 has a dual role during progression of colorectal cancer by enhancing cellular invasiveness and platinum-based chemotherapy resistance. miRNA profiling revealed that miR-153 was highly expressed in a cellular model of advanced stage colorectal cancer. Its upregulation was also noted in primary human colorectal cancer compared with normal colonic epithelium and in more advanced colorectal cancer stages compared with early stage disease. In colorectal cancer patients followed for 50 months, 21 of 30 patients with high levels of miR-153 had disease progression compared with others in this group with low levels of miR-153. Functional studies revealed that miR-153 upregulation increased colorectal cancer invasiveness and resistance to oxaliplatin and cisplatin both in vitro and in vivo. Mechanistic investigations indicated that miR-153 promoted invasiveness indirectly by inducing matrix metalloprotease enzyme 9 production, whereas drug resistance was mediated directly by inhibiting the Forkhead transcription factor Forkhead box O3a (FOXO3a). In support of the latter finding, we found that levels of miR-153 and FOXO3a were inversely correlated in matched human colorectal cancer specimens. Our findings establish key roles for miR-153 overexpression in colorectal cancer progression, rationalizing therapeutic strategies to target expression of this miRNA for colorectal cancer treatment.

Linifanib (ABT-869) enhances radiosensitivity of head and neck squamous cell carcinoma cells

OBJECTIVES

Novel targeted therapeutic strategies to overcome radio-resistance of cancer cells traditionally treated with radiation may improve patient survival with the added benefit of reduced systemic toxicity. Herein, we tested the feasibility of Linifanib (ABT-869), a multi-receptor tyrosine kinase inhibitor of members of vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) receptor families, on radio-sensitization of Head and Neck Squamous Cell Carcinoma (HNSCC).

MATERIALS AND METHODS

UMSCC-22A and UMSCC-22B cells were treated with Linifanib and γ-radiation response was determined. Cell viability, cytotoxicity, apoptosis induction and cell cycle distribution were examined by MTT assay, colony formation assay and flow cytometry. In addition, expression of STAT3 and downstream signaling proteins were assessed using western immunoblotting.

RESULTS

Treatment with Linifanib resulted in cell growth inhibition, G2/M cell cycle arrest, induction of cell death via apoptosis, reduced phosphorylation of STAT3, which has been linked to radio-resistance, lower expression of cyclin D1, survivin and increased PARP cleavage. In addition, Linifanib overcame the radio-resistance of the cell lines and significantly enhanced radiation-induced cytotoxicity (p<0.05).

CONCLUSION

These data suggest the possibility of combining targeted therapeutic such as Linifanib with radiation to enhance inhibition of cell growth and apoptosis in HNSCC cells. Thus, it may provide a novel therapeutic strategy and improve efficacy of radiation against HNSCC in the future.

Contribution of either YY1 or BclXL-induced inhibition by the NO-donor DETANONOate in the reversal of drug resistance, both in vitro and in vivo. YY1 and BclXL are overexpressed in prostate cancer

Nitric oxide (NO) donors have been shown to activate or inhibit constitutively-activated survival/anti-apoptotic pathways, such as NF-κB, in cancer cells. We report here that treatment of drug-resistant human prostate carcinoma cell lines with high levels (500-1000 μM) of the NO-donor DETANONOate sensitized the resistant tumor cells to apoptosis by CDDP and the combination was synergistic. We hypothesized that DETANONOate inhibits previously identified NF-κB-regulated resistant factors such as Yin Yang 1 (YY1) and Bcl-2/BclXL. Lysates from tumor cells treated with DETANONOate showed inhibition of YY1 and BclXL expressions. Transfection with either YY1 or BclXL siRNA resulted in the inhibition of both YY1 and BclXL expressions and sensitized the cells to CDDP apoptosis. Mice bearing PC-3 tumor xenografts and treated with the combination of DETANONOate and CDDP resulted in significant inhibition of tumor growth; treatment with single agent alone did not have any effect on tumor growth. Analysis of patients TMA tissues with prostatic cancer revealed higher expression of both YY1 and BclXL as a function of tumor grades and their levels were directly correlated. Thus, both YY1 and BclXL are potential prognostic biomarkers. Overall, the above findings suggest that one mechanism of DETANONOate-induced sensitization of resistant tumor cells to CDDP correlated with the inhibition of NF-κB and its targets YY1 and BclXL. The examination of the combination of NO donors and cytotoxic therapy in the treatment of resistant prostate cancer may be warranted.

Effects of endogenous nitric oxide and of DETA NONOate in arteriogenesis

Previous studies showed that targeted endothelial nitric oxide synthase (eNOS) disruption in mice with femoral artery occlusion does not impede and transgenic eNOS overexpression does not stimulate collateral artery growth after femoral artery occlusion, suggesting that nitric oxide from eNOS does not play a role in arteriogenesis. However, pharmacologic nitric oxide synthase inhibition with L-NAME markedly blocks arteriogenesis, suggestive of an important role of nitric oxide. To solve the paradox, we studied targeted deletion of eNOS and of inducible nitric oxide synthase (iNOS) in mice and found that only iNOS knockout could partially inhibit arteriogenesis. However, the combination of eNOS knockout and treatment with the iNOS inhibitor L-NIL completely abolished arteriogenesis. mRNA transcription studies (reverse transcriptase-polymerase chain reaction) performed on collateral arteries of rats showed that eNOS and especially iNOS (but not neural nitric oxide synthase) become upregulated in shear stress-stimulated collateral vessels, which supports the hypothesis that nitric oxide is necessary for arteriogenesis but that iNOS plays an important part. This was strengthened by the observation that the nitric oxide donor DETA NONOate strongly stimulated collateral artery growth, activated perivascular monocytes, and increased proliferation markers. Shear stress-induced nitric oxide may activate the innate immune system and activate iNOS. In conclusion, arteriogenesis is completely dependent on the presence of nitric oxide, a large part of it coming from mononuclear cells.

Tissue microarray constructs to predict a response to chemoradiation in rectal cancer

PURPOSE

To identify, using tissue microarray (TMA), an immunohistochemical panel predictive of response to ionizing radiation (IR) in rectal cancer.

METHODS

TMA constructs were prepared from archived stage II/III rectal tumors and matching adjacent mucosa (n=38) from patients treated with pre-operative chemoradiation. Immunohistochemistry (IHC) was performed for MIB, Cyclin E, p21, p27, p53, survivin, Bcl-2, and BAX. Immunoreactivity along with clinical variables was subjected to univariate and forward stepwise logistic regression analyses.

RESULTS

Pathological complete response (pCR) was 23.9%. The number of positive lymph nodes obtained in the resected specimen was associated with pCR. Immunoreactivity for MIB (Sn 15%, Sp 65%, OR 0.33), p53 (Sn 3%, Sp 84%, OR 0.16), Bcl-2 (Sn 11%, Sp 74%, OR 0.35), and BAX (Sn 92%, Sp 80%, OR 46) was associated with pathological response (all p's<0.001). Forward stepwise logistic regression analysis demonstrated that MIB was an independent predictor of a response to chemoradiation (p=0.001).

CONCLUSIONS

A combined panel of mediators of apoptosis alone or combined with clinical factors is a feasible approach that can be applied to rectal tumor biopsies to predict a response to chemoradiation. The most sensitive factor was BAX; while MIB independently predicted a response to chemoradiation.

Nitric oxide-releasing silica nanoparticle inhibition of ovarian cancer cell growth

Although the potent antitumor activity of nitric oxide (NO) supports its promise as an antineoplastic agent, effective and selective delivery and action on tumor and not normal cells remains a limiting factor. Nanoparticle-based delivery of NO has been considered as one approach to overcome these limitations. Therefore, we determined the utility of NO delivery using silica nanoparticles and evaluated their antitumor efficacy against human ovarian tumor and nontumor cells. The NO-releasing nanoparticles exhibited enhanced growth inhibition of ovarian tumor cells when compared to both control nanoparticles and a previously reported small molecule NO donor, PYRRO/NO. In addition, the NO-releasing nanoparticles showed greater inhibition of the anchorage-independent growth of tumor-derived and Ras-transformed ovarian cells. Confocal microscopy analysis revealed that fluorescently labeled NO-releasing nanoparticles entered the cytosol of the cell and localized to late endosomes and lysosomes. Furthermore, we observed a nanoparticle size dependency on efficacy against normal versus transformed ovarian cells. Our study provides the first application of nanoparticle-derived NO as an antitumor therapy and merits future studies examining nanoparticle formulation for in vivo applications.

Radiosensitization of HT-29 cells and xenografts by the nitric oxide donor DETANONOate

BACKGROUND

Mechanisms of radioresistance in rectal cancer remain unclear.

OBJECTIVES

To determine mechanisms of radioresistance in rectal cancer cells and to assess the role of the nitric oxide donor DETANONOate as a radiosensitizing agent.

METHODS

Survival was determined by clonogenic assays, apoptosis by PARP-1 cleavage, and phenotypic differences by Western blot analysis. SCID mice bearing HT-29 xenografts were treated with ionizing radiation (IR) [2.0 Gy x 5], DETANONOate [0.4 mg/kg i.p.], or combination treatment.

RESULTS

Colorectal cancer HT-29-p53-null cells were resistant and HCT-116-p53 wild-type cells sensitive to IR, which correlated with cleaved PARP-1. Increased levels of p21 occurred in HCT-116 cells, while Bcl-2 and survivin were elevated in HT-29 cells. Radiosensitization was achieved with a substantial elevation of cleaved PARP-1 in DETANONOate-HT-29-treated versus control cells, which was accompanied by elevation of p21, p27, and BAX, and a concomitant decrease in Bcl-2. SCID mice bearing HT-29 xenografts demonstrated a 37.6%, 51.1%, and 70.1% inhibition in tumor growth in mice receiving IR, DETANONOate, and combination treatment versus control, respectively.

CONCLUSIONS

Radioresistant HT-29 cells are p53-null and have substantially decreased levels of p21. DETANONOate radiosensitized HT-29 cells in vitro and in vivo by an additive effect in apoptosis.