Inhibition of hepatic metastasis from a human pancreatic adenocarcinoma (RWP-2) in the nude mouse by prostacyclin, forskolin, and ketoconazole

Econazole Induces p53-Dependent Apoptosis and Decreases Metastasis Ability in Gastric Cancer Cells

Econazole, a potent broad-spectrum antifungal agent and a Ca²⁺ channel antagonist, induces cytotoxicity in leukemia cells and is used for the treatment of skin infections. However, little is known about its cytotoxic effects on solid tumor cells. Here, we investigated the molecular mechanism underlying econazole-induced toxicity in vitro and evaluated its regulatory effect on the metastasis of gastric cancer cells. Using the gastric cancer cell lines AGS and SNU1 expressing wild-type p53 we demonstrated that econazole could significantly reduce cell viability and colony-forming (tumorigenesis) ability. Econazole induced G0/G1 phase arrest, promoted apoptosis, and effectively blocked proliferation- and survival-related signal transduction pathways in gastric cancer cells. In addition, econazole inhibited the secretion of matrix metalloproteinase- 2 (MMP-2) and MMP-9, which degrade the extracellular matrix and basement membrane. Econazole also effectively inhibited the metastasis of gastric cancer cells, as confirmed from cell invasion and wound healing assays. The protein level of p53 was significantly elevated after econazole treatment of AGS and SNU1 cells. However, apoptosis was blocked in econazole-treated cells exposed to a p53-specific small-interfering RNA to eliminate p53 expression. These results provide evidence that econazole could be repurposed to induce gastric cancer cell death and inhibit cancer invasion.

Effects of Ketoconazole on ACTH-Producing and Non-ACTH-Producing Neuroendocrine Tumor Cells

Prolonged remission of hypercortisolism with steroidogenesis inhibitors has been described in patients with ectopic adrenocorticotropic hormone (ACTH) syndrome. The anti-proliferative and pro-apoptotic effect of ketoconazole in human cancer cells was previously suggested. The aim of this study was to explore the effects of ketoconazole on ACTH-producing and non-ACTH-producing neuroendocrine tumor (NET) cell lines. The effects of ketoconazole alone, and in combination with somatostatin analogs, were evaluated in two human cell lines: DMS-79 (ectopic ACTH-producing small cell lung carcinoma) and BON-1 (human pancreatic NET). Total DNA measurement, apoptosis, cell cycle, chromogranin A (CgA)/proopiomelanocortin (POMC) expression by qRT-PCR, serotonin, CgA, and ACTH secretion assays were performed. In both cell lines, ketoconazole significantly suppressed cell growth and colony formation in a dose and time-dependent manner. The effect in DMS-79 was primarily cytotoxic, while it was more apoptotic in BON-1 cells. Ketoconazole also induced increase in G0/G1 phase in both cell lines and arrest in phase G2/M of BON-1 cells. Ketoconazole did not affect the secretion of serotonin, CgA, ACTH, or the mRNA expression of CgA and POMC. Decreased serotonin secretion was observed after the combination treatment with pasireotide. These results suggest a direct effect of ketoconazole on cell proliferation, apoptosis, and cell cycle in both ACTH- and non-ACTH-producing NET cells.

Alterations in NO- and PGI2- dependent function in aorta in the orthotopic murine model of metastatic 4T1 breast cancer: relationship with pulmonary endothelial dysfunction and systemic inflammation

Background

Patients with cancer develop endothelial dysfunction and subsequently display a higher risk of cardiovascular events. The aim of the present work was to examine changes in nitric oxide (NO)- and prostacyclin (PGI₂)-dependent endothelial function in the systemic conduit artery (aorta), in relation to the formation of lung metastases and to local and systemic inflammation in a murine orthotopic model of metastatic breast cancer.

Methods

BALB/c female mice were orthotopically inoculated with 4T1 breast cancer cells. Development of lung metastases, lung inflammation, changes in blood count, systemic inflammatory response (e.g. SAA, SAP and IL-6), as well as changes in NO- and PGI₂-dependent endothelial function in the aorta, were examined 2, 4, 5 and 6 weeks following cancer cell transplantation.

Results

As early as 2 weeks following transplantation of breast cancer cells, in the early metastatic stage, lungs displayed histopathological signs of inflammation, NO production was impaired and nitrosylhemoglobin concentration in plasma was decreased. After 4 to 6 weeks, along with metastatic development, progressive leukocytosis and systemic inflammation (as seen through increased SAA, SAP, haptoglobin and IL-6 plasma concentrations) were observed. Six weeks following cancer cell inoculation, but not earlier, endothelial dysfunction in aorta was detected; this involved a decrease in basal NO production and a decrease in NO-dependent vasodilatation, that was associated with a compensatory increase in cyclooxygenase-2 (COX-2)- derived PGI₂ production.

Conclusions

In 4 T1 metastatic breast cancer in mice early pulmonary metastasis was correlated with lung inflammation, with an early decrease in pulmonary as well as systemic NO availability. Late metastasis was associated with robust, cancer-related, systemic inflammation and impairment of NO-dependent endothelial function in the aorta that was associated with compensatory upregulation of the COX-2-derived PGI₂ pathway.

1-methylnicotinamide and its structural analog 1,4-dimethylpyridine for the prevention of cancer metastasis

Background

1-methylnicotinamide (1-MNA), an endogenous metabolite of nicotinamide, has recently gained interest due to its anti-inflammatory and anti-thrombotic activities linked to the COX-2/PGI₂ pathway. Given the previously reported anti-metastatic activity of prostacyclin (PGI₂), we aimed to assess the effects of 1-MNA and its structurally related analog, 1,4-dimethylpyridine (1,4-DMP), in the prevention of cancer metastasis.

Methods

All the studies on the anti-tumor and anti-metastatic activity of 1-MNA and 1,4-DMP were conducted using the model of murine mammary gland cancer (4T1) transplanted either orthotopically or intravenously into female BALB/c mouse. Additionally, the effect of the investigated molecules on cancer cell-induced angiogenesis was estimated using the matrigel plug assay utilizing 4T1 cells as a source of pro-angiogenic factors.

Results

Neither 1-MNA nor 1,4-DMP, when given in a monotherapy of metastatic cancer, influenced the growth of 4T1 primary tumors transplanted orthotopically; however, both compounds tended to inhibit 4T1 metastases formation in lungs of mice that were orthotopically or intravenously inoculated with 4T1 or 4T1-luc2-tdTomato cells, respectively. Additionally, while 1-MNA enhanced tumor vasculature formation and markedly increased PGI₂ generation, 1,4-DMP did not have such an effect. The anti-metastatic activity of 1-MNA and 1,4-DMP was further confirmed when both agents were applied with a cytostatic drug in a combined treatment of 4T1 murine mammary gland cancer what resulted in up to 80 % diminution of lung metastases formation.

Conclusions

The results of the studies presented below indicate that 1-MNA and its structural analog 1,4-DMP prevent metastasis and might be beneficially implemented into the treatment of metastatic breast cancer to ensure a comprehensive strategy of metastasis control.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0389-9) contains supplementary material, which is available to authorized users.

A conceptually new treatment approach for relapsed glioblastoma: coordinated undermining of survival paths with nine repurposed drugs (CUSP9) by the International Initiative for Accelerated Improvement of Glioblastoma Care

To improve prognosis in recurrent glioblastoma we developed a treatment protocol based on a combination of drugs not traditionally thought of as cytotoxic chemotherapy agents but that have a robust history of being well-tolerated and are already marketed and used for other non-cancer indications. Focus was on adding drugs which met these criteria: a) were pharmacologically well characterized, b) had low likelihood of adding to patient side effect burden, c) had evidence for interfering with a recognized, well-characterized growth promoting element of glioblastoma, and d) were coordinated, as an ensemble had reasonable likelihood of concerted activity against key biological features of glioblastoma growth. We found nine drugs meeting these criteria and propose adding them to continuous low dose temozolomide, a currently accepted treatment for relapsed glioblastoma, in patients with recurrent disease after primary treatment with the Stupp Protocol. The nine adjuvant drug regimen, Coordinated Undermining of Survival Paths, CUSP9, then are aprepitant, artesunate, auranofin, captopril, copper gluconate, disulfiram, ketoconazole, nelfinavir, sertraline, to be added to continuous low dose temozolomide. We discuss each drug in turn and the specific rationale for use- how each drug is expected to retard glioblastoma growth and undermine glioblastoma's compensatory mechanisms engaged during temozolomide treatment. The risks of pharmacological interactions and why we believe this drug mix will increase both quality of life and overall survival are reviewed.

Herbs or Natural Products That Protect Against Cancer Growth: Part Three of a Four-Part Series

PURPOSE/OBJECTIVES

To provide evidence-based research information about 47 herbs and natural products that have the potential to protect against the development of cancer.

DATA SOURCES

Natural Medicines Comprehensive Database and Lawrence Review of Natural Products-Monograph System. Information about these herbs has been found in evidence-based studies cited in the references.

DATA SYNTHESIS

Early research shows that some herbs and natural products appear to have the potential to prevent cancer growth.

CONCLUSIONS

This preliminary evidence may be useful to healthcare professionals or patients who are concerned about cancer.

IMPLICATIONS FOR NURSING

Oncology nurses who receive this information can become resources for patients or other healthcare professionals.

Molecular mechanisms of econazole-induced toxicity on human colon cancer cells: G0/G1 cell cycle arrest and caspase 8-independent apoptotic signaling pathways

Econazole (Eco), a potent broad-spectrum anti-fungal agent, has been used in the treatment of superficial mycosis. Eco is a store-operated Ca2+ channel antagonist which induces cytotoxic cell death of leukemia. However, little is known about its cytotoxic effect upon solid tumor cells. The purpose of this study is to investigate both the in vitro and in vivo molecular mechanisms of Eco-induced toxicity on colon cancer cells. We used COLO 205 cell line and nude mice xenograft model to investigate the cytotoxic effect of Eco. We demonstrated that lower doses Eco (5-20 microM) arrested human colon cancer cells at the G0/G1 phase of the cell cycle. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated while CDK2 and CDK4 kinase activity were significantly suppressed by Eco treatment in COLO 205 cells. At higher doses (40-60 microM), Eco induced COLO 205 cells apoptosis evidenced by ladder formation in DNA fragmentation assay and sub-G1 peak in flow cytometry analysis. Western blot analysis showed that caspases 3, 9 but not 8 were activated by high dose Eco treatment to the COLO 205 cells accompanied with cytochrome c and apoptosis-inducing factor (AIF) translocation. Significant anti-tumorigenesis effect was further demonstrated in vivo by treating nude mice bearing COLO 205 tumor xenografts with Eco 50 mg/kg intraperitoneally. Our findings highlight the molecular mechanisms underlying the Eco-induced toxicity on colon cancer cells.

Inhibition of human vascular endothelial cells proliferation by terbinafine

We have demonstrated previously that terbinafine (TB), an oral antifungal agent used in the treatment of superficial mycosis, suppresses proliferation of various cultured human cancer cells in vitro and in vivo by inhibiting DNA synthesis and activating apoptosis. In our study, we further demonstrated that TB at a range of concentrations (0-120 microM) dose-dependently decreased cell number in cultured human umbilical vascular endothelial cells (HUVEC). Terbinafine was not cytotoxic at a concentration of 120 microM, indicating that it may have an inhibitory effect on the cell proliferation in HUVEC. The TB-induced inhibition of cell growth rate is reversible. [(3)H]thymidine incorporation revealed that TB reduced the [(3)H]thymidine incorporation into HUVEC during the S-phase of the cell-cycle. Western blot analysis demonstrated that the protein levels of cyclin A, but not cyclins B, D1, D3, E, CDK2 and CDK4, decreased after TB treatment. The TB-induced cell-cycle arrest in HUVEC occurred when the cyclin-dependent kinase 2 (CDK2) activity was inhibited just as the protein level of p21 was increased and cyclin A was decreased. Pretreatment of HUVEC with a p21 specific antisense oligonucleotide reversed the TB-induced inhibition of [(3)H]thymidine incorporation. Taken together, these results suggest an involvement of the p21-associated signaling pathway in the TB-induced antiproliferation in HUVEC. Capillary-like tube formation and chick embryo chorioallantoic membrane (CAM) assays further demonstrated the anti-angiogenic effect of TB. These findings demonstrate for the first time that TB can inhibit the angiogenesis.

The preventive effect of ketoconazole on experimental metastasis from a human pancreatic carcinoma may be related to its effect on prostaglandin synthesis

BACKGROUND

Arachidonic acid metabolites known to affect platelet function also interfere with tumor growth and metastases. The purpose of this study was to evaluate the anti-metastatic potential of ketoconazole, a thromboxane synthetase and 5-lipoxygenase inhibitor, on hepatic metastasis from a human pancreatic adenocarcinoma in nude mice and its effect on serum prostaglandin levels.

METHODS

The human pancreatic tumor cells (RWP-2) were injected intrasplenically in nude mice grouped into control, ketoconazole (270 microg), ketoconazole (360 microg), and ketoconazole (540 microg). The agent was administered intraperitoneally 30 min before and every 24 h after the tumor cell inoculation for 8 days. In a separate experiment thromboxane B2 (TxB2), prostaglandin D2 (PGD2), prostaglandin E2 (PGE2) and 6-Keto-F1a (stable prostacyclin derivative) were measured on blood from controls, tumor bearing animals and animals bearing tumors treated with 270 microg of ketoconazole.

RESULTS

Statistically significant differences were observed between the control and three-treatment groups on the reduction of liver tumor nodules (p < 0.001), and in the liver surface areas occupied by tumor (p < 0.001). The TxB2 levels decreased from 150.6 ng/mL in the tumor bearing to 104.8 ng/mL in the ketoconazole treated animals (p < 0.05). PGD2, PGE2 and 6-keto-F1a levels increased to 7.1 ng/mL, 8.3 ng/mL, and 13.6 ng/mL from 3 ng/mL, 5.8 ng/mL, and 0.02 ng/mL respectively (p < 0.001).

CONCLUSIONS

These results indicate that ketoconazole significantly reduced hepatic metastases from the human pancreatic carcinoma RWP-2 in the nude mouse model, and inhibited thromboxane B2 formation, potentiating a concomitant redirection of platelet endoperoxide metabolism into PGD2, PGE2, and 6-keto-F1a. It is hypothesized that the changes in the arachidonic acid metabolism mediate the ameliorating effect of ketoconazole on experimental hepatic metastasis.

Antitumor effects of miconazole on human colon carcinoma xenografts in nude mice through induction of apoptosis and G0/G1 cell cycle arrest

Miconazole (MIC), a promising oral antifungal agent, has been used worldwide in the treatment of superficial mycosis. In this study, we demonstrated that MIC dose dependently arrested various human cancer cells at the G0/G1 phase of the cell cycle. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated by MIC treatment in COLO 205 cells. Electrophoretic mobility gel shift assays showed that the nuclear extracts of the MIC-treated COLO 205 cells exerted a significant binding between wild-type p53 and its consensus-binding site present in the p21/Cip1 promoter. These results suggested that the p53-associated signaling pathway is involved in the regulation of MIC-induced cancer cell growth arrest. By immunoblot analysis, we demonstrated that cyclin D3 and cyclin-dependent kinase-4 (CDK4) protein levels were inhibited by MIC treatment in the cancer cells. Significant therapeutic effect was further demonstrated in vivo by treating nude mice bearing COLO 205 tumor xenografts with MIC (50 mg/kg ip). The protein expression of p53 was significantly increased in MIC-treated tumor tissues by immunohistochemical staining and Western blotting analysis. DNA fragmentation and TUNEL assay were performed and demonstrated that apoptosis occurred in tumor tissues treated with MIC. Our study provides the novel mechanisms of antitumor effects of MIC and such results may have significant applications for cancer chemotherapy.

Mouse models of metastatic pancreatic adenocarcinoma

Pancreatic adenocarcinoma is a deadly disease. Its etiology is unknown, and metastatic disease kills the majority of patients who have it. Effective prevention is clearly the ultimate goal for eradicating this disease provided that the effects of environmental and genetic elements on pancreatic cancer development are fully understood. Currently, it appears that the control of pancreatic cancer metastasis is of immediate urgency. Fulfillment of this difficult task relies on knowledge of the cellular and molecular biology of metastasis. The use of relevant animal models will help define each aspect of this complicated process.

Ketoconazole induces G0/G1 arrest in human colorectal and hepatocellular carcinoma cell lines

Ketoconazole is an oral-antifungal agent that has been used worldwide in the treatment of some hormone-dependent human cancer. In this study, we demonstrated that ketoconazole (20 microM) induced various types of human cancer cell growth arrest in the G0/G1 phase. Our results revealed that ketoconazole-induced growth arrest was more profound in COLO 205 and Hep G2 (with wild-type p53) than in HT 29 (p53 His(273) mutant) and Hep 3B (with deleted p53) cells. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated by ketoconazole (10 microM) treatment in COLO 205 but not in HT 29 cells. The ketoconazole-induced G0/G1 phase arrest in COLO 205 cells was attenuated by p53-specific antisense oligodeoxynucleotides (20 microM) treatment. These results suggested that the p53-associated signaling pathway is involved in the regulation of ketoconazole-induced cancer cell growth arrest. By Western blot analysis, we demonstrated that cyclin D3 and CDK4 protein but not other G0/G1 phase regulatory protein levels were decreased by ketoconazole-treatment in both COLO 205 and HT 29 cells. Our study provides the basis of molecular mechanisms for ketoconazole in growth inhibition of human cancer cells and such results may have significant applications for cancer chemotherapy.

Vinblastine and 5-fluorouracil sensitivity of xenografts of four pancreatic ductal adenocarcinomas: is there a correlation with histological and cytological tumour differentiation?

In a search for nuclear parameters which may predict chemosensitivity of ductal adenocarcinoma of the pancreas, the growth of four xenografted pancreatic carcinomas in response to chemotherapeutic agents was correlated with histological and cytological features of tumour differentiation. Histologically, the tumours were classified according to their ability to form glands into poorly (PaTu-2, PaTu-3), moderately (Panc-1) and well differentiated (PaTu-39) ductal adenocarcinomas. Cytologically, similar segregation of tumours was possible using the 'nuclear form factor', which was one of four nuclear parameters analysed by image cytometry on Feulgen stained tumour imprints. Histological and cytological differentiation correlated closely with tumour growth. One week after a single intraperitoneal injection of either vinblastine or 5-fluorouracil, both drugs inhibited the growth of PaTu-2 and PaTu-3 significantly. The growth of Panc-1 was only affected by vinblastine, while neither drug had an effect on PaTu-39. The results suggest that the response of pancreatic ductal adenocarcinoma to chemotherapeutic drugs may be, to some extent, predicted by histological and cytological differentiation features. However, within these lines, each tumour may show a specific response pattern.

Prostacyclin and its analogues: antimetastatic effects and mechanisms of action

More than a decade ago, prostacyclin, a dienoic bicyclic eicosanoid derived from the metabolism of arachidnoic acid, was found to possess potent inhibitory effects on tumor cell metastasis. Thereafter, several laboratories demonstrated the metastasis-suppressive activity of prostacyclin in a wide spectrum of tumor types. Due to the short half-life of prostacyclin, researchers have focused on looking for stable prostacyclin analogues which have extended half lives and increased bioavailabilities. Cicaprost, among other prostacyclin analogues tested, has been demonstrated, like prostacyclin, to effectively inhibit metastasis in several different animal models (i.e., both experimental and spontaneous metastasis models). Prostacyclin as well as cicaprost prevent not only hematogenous, but also lymphatic metastasis. Furthermore, these compounds also inhibit the growth of established micrometastases after removal of the primary tumors. Mechanistic studies revealed that the antimetastatic effects of prostacyclin and its analogues are more related to their interference with tumor cell-host interactions (such as tumor cell induced platelet aggregation, tumor cell adhesion to endothelial cells and subendothelial matrix, tumor cell induced endothelial cell retraction, etc.) than their direct inhibition of the growth of primary tumors. The potent and widespread metastasis-retarding effects of prostacyclin and its stable analogues in animal tumor models warrant their clinical trial in treating human cancer patients and preventing metastasis.

Fatty acid modulation of tumor cell-platelet-vessel wall interaction

Prostaglandins and other eicosanoids have been studied extensively in their physical, biochemical, biophysical and pharmacological aspects. However, studies on their role in tumor progression, especially metastases are relatively recent. Following a brief overview of the history of discovery and metabolism of eicosanoids and other fatty acids, we discuss the functions of these fatty acids (with emphasis on prostacyclin, thromboxane A2, 12-hydroxyeicosatetraenoic acid and 13-hydroxyoctadecadienoic acid) in cell transformation, tumor promotion and particularly in tumor cell metastasis. The relation between these monohydroxy fatty acids and tumor cell metastasis is discussed from three different perspectives, i.e., their effects on tumor cells, on platelets and on endothelial cells. The mechanism of these effects are then addressed at cell adhesion molecule, motility, protease, cell cytoskeleton, protein kinase and eicosanoid receptor levels. Finally, regulation of three key enzymes which generate eicosanoids (phospholipase, prostaglandin endoperoxide synthase and lipoxygenase) is explored.

The inhibition of platelet aggregation of metastatic H-ras-transformed 10T1/2 fibroblasts with castanospermine, an N-linked glycoprotein processing inhibitor

A series of T24-H-ras-transformed 10T1/2 fibroblasts with varying metastatic potential was tested for the ability to aggregate platelets. Results indicate that although platelet activation was always detected in the highly metastatic cells, some non-metastatic cells also have the ability to cause platelet aggregation, suggesting that this is a necessary but not sufficient characteristic of the metastatic phenotype. Apyrase, an ADP scavenger, effectively inhibited platelet aggregation by metastatic cells, however, there was no significant increase in ADP secretion or relation to the ability of the tumor cells to activate platelets. Hirudin, a thrombin inhibitor, did not affect aggregation, suggesting that the pathway of activation is thrombin-independent. The glycoprotein processing inhibitor, castanospermine, which reduces glycosidase I activity and metastatic capability, inhibited the ability of metastatic cells to cause platelet aggregation. However, another inhibitor of oligosaccharide processing, swainsonine, which inhibits mannosidase II activity and does not reduce metastasis, had no effect on platelet aggregation. These results show that the integrity of N-linked oligosaccharide structure of glycoproteins is an important feature of the ability of ras-transformed fibroblasts to activate platelets.

Effects of antiplatelet agents alone or in combinations on platelet aggregation and on liver metastases from a human pancreatic adenocarcinoma in the nude mouse

There is ample evidence to suggest that hematogenous metastasis may be related to the ability of tumor cells to promote aggregation of host platelets. Arachidonic acid metabolism in platelets and vessel walls may also contribute to the metastatic process. Several preliminary trials of platelet inhibitory agents have been performed. Ketoconazole (inhibitor of lipoxygenase and thromboxane synthetase), verapamil (calcium antagonist), forskolin (stimulator of platelet adenylate cyclase), and indomethacin (inhibitor of cyclooxygenase) were examined, alone and in combination, to investigate their effects on platelet aggregation and on hepatic metastases from human pancreatic tumor cells (RWP-2) in nude mice. The tumor cells were injected intrasplenically, and the animals were divided into control, single-drug and combination treatment groups. The agents were administered intraperitoneally 1 hr before and every 24 hr after the tumor cell injections for 6 days. Statistically significant differences were observed between the control and single-treatment groups on the reduction of liver tumor nodules (range P less than 0.001-0.032) and in the liver surface areas occupied by tumor (range P less than 0.001-0.013). Furthermore, when these agents were combined, similar reductions in liver tumor nodules were noted (range P less than 0.001-0.008), while even greater inhibitory effects were seen in the liver surface areas occupied by tumor (P less than 0.001) compared with the single-treatment groups. Also, the combination studies strongly inhibited RWP-2-induced platelet aggregation in human platelet-rich plasma.

Role of levamisole as immunomodulant in mouse lymphoma model

Levamisole (LMS) has been considered an immunorestorative agent capable of enhancing host's antitumor immune responses. Clinical studies showed that LMS plays a significant role in adjuvant chemotherapy of colorectal cancer. Therefore studies were performed to test whether LMS would be able to restore graft responsiveness in mice with drug-dependent, age-dependent or virus-dependent immunodeficiency. The results show that LMS has little or no influence on the limited antitumor effects of Dacarbazine or Ara-C in mice bearing allogeneic leukemias (i.e. in a host-tumor model in which immuno-chemotherapy synergism occurs with less immunodepressive anticancer drugs). Moreover LMS does not alleviate allograft response inhibition produced by high-dose Dacarbazine or by a mouse RNA virus. However the agent restored graft responsiveness in aged animals. The limited immunoenhancing effects of LMS, as detected in the present study, suggest that the clinical efficacy of the agent could be due to mechanisms not entirely related to its immunopharmacological properties.