All-trans retinoic acid and protein kinase C α/ß1 inhibitor combined treatment targets cancer stem cells and impairs breast tumor progression.

Breast cancer is the leading cause of cancer death among women worldwide. Blocking a single signaling pathway is often an ineffective therapy, especially in the case of aggressive or drug-resistant tumors. Since we have previously described the mechanism involved in the crosstalk between Retinoic Acid system and protein kinase C (PKC) pathway, the rationale of our study was to evaluate the effect of combining all-trans-retinoic acid (ATRA) with a classical PCK inhibitor (Gö6976) in preclinical settings. Employing hormone-independent mammary cancer models, Gö6976 and ATRA combined treatment induced a synergistic reduction in proliferative potential that correlated with an increased apoptosis and RARs modulation towards an anti-oncogenic profile. Combined treatment also impairs growth, self-renewal and clonogenicity potential of cancer stem cells and reduced tumor growth, metastatic spread and cancer stem cells frequency in vivo. An in-silico analysis of "Kaplan-Meier plotter" database indicated that low PKCα together with high RARα mRNA expression is a favorable prognosis factor for hormone-independent breast cancer patients. Here we demonstrate that a classical PKC inhibitor potentiates ATRA antitumor effects also targeting cancer stem cells growth, self-renewal and frequency.

Pharmacological Approaches in an Experimental Model of Non-Small Cell Lung Cancer: Effects on Tumor Biology.

Lung cancer (LC) remains the leading cause of cancer mortality worldwide, and non-small cell LC (NSCLC) represents 80% of all LC. Oxidative stress and inflammation, autophagy, ubiquitin-proteasome system, nuclear factor (NF)-κB, and mitogen activated protein kinases (MAPK) participate in LC pathophysiology. Currently available treatment for LC is limited and in vivo models are lacking. We hypothesized that antioxidants and NF- κB, MAPK, and proteasome inhibitors may exert an antitumoral response through attenuation of several key biological mechanisms that promote tumorigenesis and cancer cell growth. Body and tumor weights, oxidative stress, antioxidants, inflammation, NF-κB p65 expression, fibulins, apoptosis, autophagy, tumor and stroma histology were evaluated in the subcutaneous tumor of LC (LP07 adenocarcinoma) BALB/c mice, with and without concomitant treatment with NF-κB (sulfasalazine), MEK (U0126), and proteasome (bortezomib) inhibitors, and N-acetyl cysteine (NAC). Compared to LC control mice, in subcutanous tumors, the four pharmacological agents reduced oxidative stress markers and tumor proliferation (ki-67). Inflammation and NF-κB p65 expression were attenuated by NF-κB and MAPK inhibitors, and the latter also enhanced apoptotic markers. Catalase was induced by the three inhibitors, while bortezomib also promoted superoxide dismutase expression. NF-κB and MEK inhibitors significantly reduced tumor burden through several biological mechanisms that favored tumor degradation and attenuated tumor proliferation. These two pharmacological agents may enhance the anti-tumor activity of selectively targeted therapeutic strategies for LC. Proteasomal inhibition using bortezomib rather promotes tumor degradation, while treatment with antioxidants cannot be recommended. This experimental model supports the use of adjuvant drugs for the improvement of LC treatment.

Differential response of myeloid-derived suppressor cells to the nonsteroidal anti-inflammatory agent indomethacin in tumor-associated and tumor-free microenvironments.

Myeloid-derived suppressor cells (MDSCs) are key regulatory cells that control inflammation and promote tumor-immune escape. To date, no specific immunomodulatory drug has proven efficacy in targeting the expansion and/or function of these cells in different pathophysiologic settings. In this study, we identified a context-dependent effect of the nonsteroidal anti-inflammatory drug indomethacin (IND) on MDSCs, depending on whether they were derived from tumor microenvironments (TME) or from tumor-free microenvironments (TFME). Treatment of mice bearing the LP07 lung adenocarcinoma with IND inhibited the suppressive activity of splenic MDSCs, which restrained tumor growth through mechanisms involving CD8(+) T cells. The same effect was observed when MDSCs were treated with IND and conditioned media from LP07 tumor cells in vitro. However, in the absence of a tumor context, IND enhanced the intrinsic suppressive function of MDSCs and amplified their protumoral activity. In a model of autoimmune neuroinflammation, IND-treated MDSCs differentiated in TFME attenuated inflammation, whereas IND-treated MDSCs differentiated in TME aggravated clinical symptoms and delayed resolution of the disease. Mechanistically, IND reduced arginase activity as well as NO and reactive oxygen species production in MDSCs differentiated in TME but not in TFME. Moreover, expression of the C/EBP-ß transcription factor isoforms correlated with the suppressive activity of IND-treated MDSCs. Our study unveils the dual and context-dependent action of IND, a drug that serves both as an anti-inflammatory and anticancer agent, which differentially affects MDSC activity whether these cells are derived from TME or TFME. These results have broad clinical implication in cancer, chronic inflammation and autoimmunity.

Pharmacological strategies in lung cancer-induced cachexia: effects on muscle proteolysis, autophagy, structure, and weakness.

Cachexia is a relevant comorbid condition of chronic diseases including cancer. Inflammation, oxidative stress, autophagy, ubiquitin-proteasome system, nuclear factor (NF)-κB, and mitogen-activated protein kinases (MAPK) are involved in the pathophysiology of cancer cachexia. Currently available treatment is limited and data demonstrating effectiveness in in vivo models are lacking. Our objectives were to explore in respiratory and limb muscles of lung cancer (LC) cachectic mice whether proteasome, NF-κB, and MAPK inhibitors improve muscle mass and function loss through several molecular mechanisms. Body and muscle weights, limb muscle force, protein degradation and the ubiquitin-proteasome system, signaling pathways, oxidative stress and inflammation, autophagy, contractile and functional proteins, myostatin and myogenin, and muscle structure were evaluated in the diaphragm and gastrocnemius of LC (LP07 adenocarcinoma) bearing cachectic mice (BALB/c), with and without concomitant treatment with NF-κB (sulfasalazine), MAPK (U0126), and proteasome (bortezomib) inhibitors. Compared to control animals, in both respiratory and limb muscles of LC cachectic mice: muscle proteolysis, ubiquitinated proteins, autophagy, myostatin, protein oxidation, FoxO-1, NF-κB and MAPK signaling pathways, and muscle abnormalities were increased, while myosin, creatine kinase, myogenin, and slow- and fast-twitch muscle fiber size were decreased. Pharmacological inhibition of NF-κB and MAPK, but not the proteasome system, induced in cancer cachectic animals, a substantial restoration of muscle mass and force through a decrease in muscle protein oxidation and catabolism, myostatin, and autophagy, together with a greater content of myogenin, and contractile and functional proteins. Attenuation of MAPK and NF-κB signaling pathway effects on muscles is beneficial in cancer-induced cachexia.

Modulation of pancreatic tumor potential by overexpression of protein kinase C ß1.

OBJECTIVE: This study aimed to investigate whether the overexpression of protein kinase C ß1 (PKCß1) is able to modulate the malignant phenotype displayed by the human ductal pancreatic carcinoma cell line PANC1. METHODS: PKCß1 overexpression was achieved using a stable transfection approach. PANC1-PKCß1 and control cells were analyzed both in vitro and in vivo. RESULTS: PANC1-PKCß1 cells displayed a lower growth capacity associated with the down-regulation of the MEK/ERK pathway and cyclin expression. Furthermore, PKCß1 overexpression was associated with an enhancement of cell adhesion to fibronectin and with reduced migratory and invasive phenotypes. In agreement with these results, PANC1-PKCß1 cells showed an impaired ability to secrete proteolytic enzymes. We also found that PKCß1 overexpressing cells were more resistant to cell death induced by serum deprivation, an event associated with G0/G1 arrest and the modulation of PI3K/Akt and NF-κB pathways. Most notably, the overexpression of PKCß1 completely abolished the ability of PANC1 cells to induce tumors in nude mice. CONCLUSIONS: Our results established an important role for PKCß1 in PANC1 cells suggesting it would act as a suppressor of tumorigenic behavior in pancreatic cancer.

Anti-tumor effect of SLPI on mammary but not colon tumor growth.

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that was related to cancer development and metastasis dissemination on several types of tumors. However, it is not known the effect of SLPI on mammary and colon tumors. The aim of this study was to examine the effect of SLPI on mammary and colon tumor growth. The effect of SLPI was tested on in vitro cell apoptosis and in vivo tumor growth experiments. SLPI over-expressing human and murine mammary and colon tumor cells were generated by gene transfection. The administration of murine mammary tumor cells over-expressing high levels of SLPI did not develop tumors in mice. On the contrary, the administration of murine colon tumor cells over-expressing SLPI, developed faster tumors than control cells. Intratumoral, but not intraperitoneal administration of SLPI, delayed the growth of tumors and increased the survival of mammary but not colon tumor bearing mice. In vitro culture of mammary tumor cell lines treated with SLPI, and SLPI producer clones were more prone to apoptosis than control cells, mainly under serum deprivation culture conditions. Herein we demonstrated that SLPI induces the apoptosis of mammary tumor cells in vitro and decreases the mammary but not colon tumor growth in vivo. Therefore, SLPI may be a new potential therapeutic tool for certain tumors, such as mammary tumors.

Inhibition of tumor progression and paraneoplastic syndrome development in a murine lung adenocarcinoma by medroxyprogesterone acetate and indomethacin.

Mice bearing LP07 lung adenocarcinoma present some characteristics similar to those shown in patients with several malignant diseases. LP07 tumor bearers develop paraneoplastic syndromes such as cachexia, leukocytosis, and hypercalcemia, partly due to a systemic inflammatory response. We analyzed some of the mechanisms involved in the effectiveness of the association of the appetite-stimulant medroxiprogesterone acetate (MPA) and the nonselective cyclooxigenase (COX) inhibitor indomethacin (INDO) in LP07 tumor bearing mice. INDO and INDO plus MPA treatments significantly inhibited tumor growth, which was not inhibited by MPA. The number of lung metastatic nodules was decreased with all treatments, being most effective INDO alone and INDO plus MPA. A significant decrease of plasmatic levels of the matrix metalloproteinases MMP-9 and MMP-2 correlated with these results. Paraneoplastic syndromes, leukocytosis, and cachexia were abolished by all treatments. We determined effects of the treatments on circulating cytokines shown to regulate cachexia and inflammation. Both treatments alone, and INDO plus MPA, reduced circulating IL-6 throughout tumor evolution. A pronounced increase in serum IL-1ss levels was detected in untreated tumor bearers. These levels decreased and were closer to normal serum values when LP07 mice were treated with INDO plus MPA. The combination of a nonsteroidal antiinflammatory drug as INDO and MPA showed to be effective in inhibiting tumor and metastatic growth and diminishing paraneoplastic symptoms and SIR. A variety of specific molecules are implicated as playing a role in cancer-induced cachexia and hematological alterations.

Reduction of tumor progression and paraneoplastic syndrome development in murine lung adenocarcinoma by nonsteroidal antiinflammatory drugs.

Mice bearing LP07 lung adenocarcinoma show some characteristics that are similar to those present in patients with NSCLC. LP07 tumor-bearing mice develop the paraneoplastic syndromes of cachexia, leukocytosis and hypercalcemia. These symptoms may be partly due to a systemic inflammatory response. Our aim was to determine if treatment with NSAIDs would lower tumor and metastasis growth and their accompanying syndromes. The nonselective COX inhibitor indomethacin and the selective COX-2 inhibitor celecoxib reduced tumor growth and metastasis outcome in s.c. LP07 tumor-bearing mice. Both drugs also inhibited the development of leukocytosis and the weight loss associated with LP07 progression. Serum levels of the inflammatory cytokines IL-1beta and IL-6, mediators of cachexia, were modulated by NSAIDs. Inhibition of in vitro migration and invasion and reduction in angiogenesis were attained when cells were treated with either indomethacin or celecoxib. MMP-9 activity was also reduced in conditioned media from LP07 cells treated with celecoxib. These data suggest that several processes implicated in tumor progression can be modulated with NSAID treatment. Improvement in performance status through modulation of cachexia may offer a possibility for combining anti-inflammatory treatments with more aggressive therapies.

Malignant myoepithelial cells are associated with the differentiated papillary structure and metastatic ability of a syngeneic murine mammary adenocarcinoma model.

BACKGROUND: The normal duct and lobular system of the mammary gland is lined with luminal and myoepithelial cell types. Although evidence suggests that myoepithelial cells might suppress tumor growth, invasion and angiogenesis, their role remains a major enigma in breast cancer biology and few models are currently available for exploring their influence. Several years ago a spontaneous transplantable mammary adenocarcinoma (M38) arose in our BALB/c colony; it contains a malignant myoepithelial cell component and is able to metastasize to draining lymph nodes and lung. METHODS: To characterize this tumor further, primary M38 cultures were established. The low-passage LM38-LP subline contained two main cell components up to the 30th subculture, whereas the higher passage LM38-HP subline was mainly composed of small spindle-shaped cells. In addition, a large spindle cell clone (LM38-D2) was established by dilutional cloning of the low-passage MM38-LP cells. These cell lines were studied by immunocytochemistry, electron microscopy and ploidy, and syngeneic mice were inoculated subcutaneously and intravenously with the different cell lines, either singly or combined to establish their tumorigenic and metastatic capacity. RESULTS: The two subpopulations of LM38-LP cultures were characterized as luminal and myoepithelium-like cells, whereas LM38-HP was mainly composed of small, spindle-shaped epithelial cells and LM38-D2 contained only large myoepithelial cells. All of them were tumorigenic when inoculated into syngeneic mice, but only LM38-LP cultures containing both conserved luminal and myoepithelial malignant cells developed aggressive papillary adenocarcinomas that spread to lung and regional lymph nodes. CONCLUSION: The differentiated histopathology and metastatic ability of the spontaneous transplantable M38 murine mammary tumor is associated with the presence and/or interaction of both luminal and myoepithelial tumor cell types.

Effects of celecoxib, medroxyprogesterone, and dietary intervention on systemic syndromes in patients with advanced lung adenocarcinoma: a pilot study.

Systemic syndromes characterized by a persistent activity of circulating mediators (cytokines) are frequently present with advanced cancer. We grouped under the general heading of "Systemic Immune-Metabolic Syndrome (SIMS)" a particular variety of distressing systemic syndrome characterized by dysregulation of the psycho-neuro-immune-endocrine homeostasis, with overlapping clinical manifestations. SIMS may include cachexia, anorexia, nausea, early satiety, fatigue, tumor fever, cognitive changes and superinfection. The aim of this study was to ameliorate some of the SIMS symptoms in a homogeneous group of lung adenocarcinoma patients using a multitargeted therapy. Fifteen patients with evidence of SIMS were studied. SIMS was defined as the presence of weight loss, anorexia, fatigue performance status>/=2 and acute-phase protein response. Patients received medroxyprogesterone (MPA) (500 mg twice daily), celecoxib (200 mg twice daily), plus oral food supplementation for 6 weeks. After treatment, 13 patients either had stable weight (+/- 1%) or had gained weight. There were significant differences in improvement of body-weight-change rate, nausea, early satiety, fatigue, appetite and performance status. Patients who had any kind of lung infection showed higher levels of IL-10 compared to non-infected patients (P=0.039). Our results suggest that patients with advanced lung adenocarcinoma, treated with MPA, celecoxib and dietary intervention, might have considerable improvement in certain SIMS outcomes. This multitargeted symptomatic approach deserves further study.

Arginine metabolic pathways involved in the modulation of tumor-induced angiogenesis by macrophages.

Neovascularization, an essential step for tumor progression and metastasis development, can be modulated by the presence of macrophages (Mps) in the tumor microenvironment. The ability of Mps to regulate the angiogenicity of the LMM3 tumor cell line was studied. Peritoneal Mps from LMM3 tumor-bearing mice (TMps) potentiate in vivo LMM3 angiogenicity. These results were confirmed by CD31 immunoblotting assays. The activity of TMps depended on nitric oxide synthase (NOS) and arginase (A) activity. By immunoblotting we evidenced that AI and AII isoforms were up-regulated in TMps while the inducible and neuronal NOS isoforms were highly expressed in normal Mps. TMps might positively modulate tumor growth by stimulating angiogenic cascade mainly through polyamine synthesis.

Inmunorregulación del crecimiento tumoral en un sistema murino / Immunoregulation of tumor growth in a murine model

Estudiamos la regulación del crecimiento tumoral y metastásico tanto por el propio tumor como por el sistema inmune, en un modelo murino. Sobrenadantes de cultivo de esplenocitos de portadores de tumor exacerban el crecimiento del propio tumor. Esta actividad desaparece luego de la cirugía tumoral pero con una cinética diferente dependendo de si el tumor es precoz o avanzado al tiempo de la cirugía. Las poblaciones esplénicas involucradas en la exacerbación varían durante el crecimiento del tumor mientras que las responsables de inducción de angiogénesis son siempre de naturaleza T. Con respecto de la autorregulación tumoral, encontramos que diferentes formas de antígenos tumorales (extractos tumorales, sobrenadantes de cultivo de células tumorales, células tumorales formolizadas) aumentan la diseminación metastásica, pero esta actividad está mediada por el sistema inmune del huésped. Por el contrario, sobrenadantes de cultivo de células tumorales no inducen exacerbación del tumor primario. Las células tumorales fueron tratadas con un modificador de membrana con la expectativa de alterar la respuesta inmune antitumoral

Inmunorregulación del crecimiento tumoral en un sistema murino / Immunoregulation of tumor growth in a murine model

Estudiamos la regulación del crecimiento tumoral y metastásico tanto por el propio tumor como por el sistema inmune, en un modelo murino. Sobrenadantes de cultivo de esplenocitos de portadores de tumor exacerban el crecimiento del propio tumor. Esta actividad desaparece luego de la cirugía tumoral pero con una cinética diferente dependendo de si el tumor es precoz o avanzado al tiempo de la cirugía. Las poblaciones esplénicas involucradas en la exacerbación varían durante el crecimiento del tumor mientras que las responsables de inducción de angiogénesis son siempre de naturaleza T. Con respecto de la autorregulación tumoral, encontramos que diferentes formas de antígenos tumorales (extractos tumorales, sobrenadantes de cultivo de células tumorales, células tumorales formolizadas) aumentan la diseminación metastásica, pero esta actividad está mediada por el sistema inmune del huésped. Por el contrario, sobrenadantes de cultivo de células tumorales no inducen exacerbación del tumor primario. Las células tumorales fueron tratadas con un modificador de membrana con la expectativa de alterar la respuesta inmune antitumoral (AU)