Synergistic effect of low-dose cucurbitacin B and low-dose methotrexate for treatment of human osteosarcoma

We investigated the use of cucurbitacin B, a plant-derived tetracyclic triterpenoid, as a single agent or in combination with methotrexate (MTX) for human osteosarcoma (OS) treatment. Cucurbitacin B showed antiproliferative activity against seven human OS cell lines in vitro accompanying G2/M cell cycle arrest, apoptosis, and inhibition of ERK, Akt, and mTOR proteins. Cucurbitacin B in combination with MTX synergistically inhibited OS cell growth in vitro. Low-dose cucurbitacin B (LD-CuB, 0.5 mg/kg body weight) or low-dose MTX (LD-MTX, 150 mg/kg) failed to decrease the size of human OS xenografts in nude mice. However, combined therapy at identical concentrations inhibited tumor growth by 62% vs. LD-CuB and 81% vs. LD-MTX (p<0.001). Strikingly, the effect persisted even when the dose of MTX was decreased by two thirds (VLD-MTX, 50 mg/kg). In conclusion, cucurbitacin B alone or in combination with MTX shows promising antiproliferative activity against human OS.

Cucurbitacin B, a novel in vivo potentiator of gemcitabine with low toxicity in the treatment of pancreatic cancer

BACKGROUND AND PURPOSE

Pancreatic cancer is a highly aggressive malignancy, and improvement in systemic therapy is necessary to treat this frequently encountered metastatic disease. The current targeted agents used in combination with gemcitabine improved objective response rates, but with little or no improvements in survival and also increased toxicities in pancreatic cancer patients. Recently, we showed that the triterpenoid cucurbitacin B inhibited tumour growth in pancreatic cancer cells by inhibition of the JAK/STAT pathway, and synergistically increased antiproliferative effects of gemcitabine in vitro.

EXPERIMENTAL APPROACH

The anti-tumour effects and toxicities of cucurbitacin B in combination with gemcitabine were tested against human pancreatic cancer cells in a murine xenograft model.

KEY RESULTS

Combined therapy with cucurbitacin B and gemcitabine at relatively low doses (0.5 mg x kg(-1) and 25 mg x kg(-1) respectively) resulted in highly significant tumour growth inhibition of pancreatic cancer xenografts (up to 79%). Remarkably, this therapy was well tolerated by the animals, as shown by histology of visceral organs, analysis of serum chemistry, full blood counts and bone marrow colony numbers. Western blot analysis of the tumour samples of mice who received both cucurbitacin B and gemcitabine, revealed stronger inhibition of Bcl-XL, Bcl-2 and c-myc, and higher activation of the caspase cascades, than mice treated with either agent alone.

CONCLUSIONS AND IMPLICATIONS

Combination of cucurbitacin B and gemcitabine had profound anti-proliferative effects in vivo against xenografts of human pancreatic cancer cells, without any significant signs of toxicity. This promising combination should be examined in therapeutic trials of pancreatic cancer.

Abstract 5396: Synergistic effect of cucurbitacin B and low-dose methotrexate for treatment of human osteosarcoma

Human osteosarcoma (OS) is well known for its metastasis and high recurrence rate even after aggressive treatment. Although current chemotherapeutic regimens have greatly improved the 5-year overall survival rate of the OS patients from 20 % to 70 %, only a limited number of drugs are available to treat OS patients, which makes the development of better treatment protocols difficult. In this research, we tested cucurbitacin B as a potential chemotherapeutic agent for the treatment of human OS. Cucurbitacin B is a plant-derived tetracyclic triterpenoid known to have an antiproliferative effect on several human cancers.

In our research, cucurbitacin B showed an antiproliferative effect on 6 human OS cell lines in vitro (ED50 = ∼5×10^-8 M), and the response was dose- and time-dependent. These cells underwent marked morphological changes, multinucleation, G2/M cell cycle arrest, and subsequent cell death. This antiproliferative effect of cucurbitacin B as tested on MG-63 and SAOS-2 human OS cell lines was mainly achieved by the down-regulation of mTOR (mammalian target of rapamycin) pathway through decreased activation of ERK (extraceullar signal-related kinase) independent of Akt phosphorylation. This led to the subsequent inhibition of the downstream targets such as ribosomal protein S6 kinase (S6K) and eukaryotic translation initiation factor 4E binding protein 1 (4EBP1).

Interestingly, when MG-63 and SAOS-2 cells were exposed to both cucurbitacin B and methotrexate (MTX) in combination in vitro, their growth was significantly and synergistically inhibited (combination index (CI) &lt; 0.9). For this reason, we used MG-63 xenografts in athymic nude mice to test if cucurbitacin B can augment the therapeutic effect of MTX in vivo. Whereas low-dose cucurbitacin B (0.5 mg/kg body weight) or low-dose MTX (150 mg/kg body weight) alone failed to decrease the tumor size, the combination of the two compounds at these concentrations significantly inhibited the tumor growth by 70 %. Strikingly, similar synergism was observed even when the MTX was lowered to 50 mg/kg body weight. No significant toxicity was found in combination groups compared to monotherapeutic regimen in terms of body weight loss, bone-marrow clonogenic growth, or a variety of whole-blood and serum parameters.

In conclusion, cucurbitacin B showed a promising antiproliferative activity against human OS. We also identified for the first time that mTOR pathway was down-regulated through the inhibition of ERK by cucurbitacin B in human OS cells. Moreover, strong synergistic effects of cucurbitacin B with low-dose methotrexate were observed both in vitro and in vivo. Considering that many current chemotherapeutic regimens require a high-dose of methotrexate (2,400 mg/kg body weight) including leucovorin rescue, the use of cucurbitacin B with low-dose methotrexate provides a promising clinical option for the treatment of human OS.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5396.

Abstract 5383: Cucurbitacin B, a novel in vivo potentiator of gemcitabine with low toxicity in the treatment of pancreatic cancer

Pancreatic cancer is a highly aggressive malignancy, and improvement in systemic therapy is necessary to treat this frequently encountered metastatic disease. The current targeted agents used in combination with gemcitabine improved objective response rates, but with little or no improvements in survival and also increased toxicities in pancreatic cancer patients. Recently, we showed that the triterpenoid cucurbitacin B inhibited tumor growth in pancreatic cancer cells by inhibition of the JAK/STAT pathway, and synergistically increased antiproliferative effects of gemcitabine in vitro. The anti-tumor and toxicity effects of cucurbitacin B in combination with gemcitabine were tested against human pancreatic cancer cells in a murine xenograft model. The combinatory therapy of cucurbitacin B and gemcitabine at relatively low doses (0.5 mg/kg and 25 mg/kg, respectively) resulted in highly significant tumor growth inhibition of pancreatic cancer xenografts by up to 79% (p&lt;0.001). Remarkably, this therapy was well tolerated by the animals, including histology of inner organs, analysis of serum chemistries, full blood counts, and bone marrow colony numbers. Western blot analysis of the tumor samples of mice who received both agents, cucurbitacin B and gemcitabine, revealed stronger inhibition of Bcl-XL, Bcl-2 and c-myc, and higher activation of the caspase-cascades compared to single agent treated mice. The in vivo combination therapy of cucurbitacin B and gemcitabine has profound antiproliferative effects against human pancreatic cancer cells, without any significant signs of toxicity. This promising combination should be examined in therapeutic trials of pancreatic cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5383.

Abstract 245: An oncogenic role for CCAAT/enhancer binding protein beta in non-small cell lung cancer

The transcription factor CCAAT/enhancer binding protein (C/EBP) beta is known to be a mediator of cellular transformation and tumorigenesis in human colon, breast and ovary cancer. In this study, we focused on C/EBPbeta and its potential role in non-small cell lung cancer (NSCLC). Immunohistochemical staining of 60 human NSCLC samples (adeno- (31), squamous cell - (25), small cell - (1), large cell - (2), and adeno-squamous cell (1) carcinoma) showed that more than 50% of the tumor samples were significantly positive for nuclear staining of C/EBPbeta compared to healthy airway epithelial cells. Retrovirus-delivered siRNA knock-down of C/EBPbeta expression in human NSCLC cell lines A549, H520, and H460 markedly reduced clonogenic growth, which was accompanied by a significant reduction in cyclooxygenase(COX)-2 expression, increase in G0/G1 cells, and PARP cleavage activity. In contrast, using NSCLC cell line Calu-3 with a moderate intrinsic level of C/EBPbeta, forced expression of this transcription factor even increased clonogenic growth and cell proliferation. Whereas recent studies suggested that family member C/EBPalpha has growth-inhibitory properties in airway epithelial cells, our present data indicate an oncogenic role of C/EBPbeta in NSCLC and may represent a new target for cancer co-therapy to increase response to existing chemotherapeutic regimens.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 245.

Cucurbitacin: ancient compound shedding new light on cancer treatment

Cucurbitacins and their derivatives are triterpenoids found in medicinal plants known for their diverse pharmacological and biological activities, including anticancer effects, throughout human history. Although initial attention to cucurbitacin as a potential anticancer drug withered for decades, recent discoveries showing that cucurbitacin is a strong STAT3 (Signal Transducers and Activators of Transcription-3) inhibitor have reclaimed the attention of the drug industry one more time. There is increasing evidence showing that some cucurbitacins not only inhibit the JAK-STAT pathway, but also affect other signaling pathways, such as the MAPK pathway, which are also known to be important for cancer cell proliferation and survival. Moreover, some reports have shown the synergistic effect of cucurbitacins with known chemotherapeutic agents, such as doxorubicin and gemcitabine. In this review, we will summarize the recent discoveries regarding molecular mechanisms of action of cucurbitacins in human cancer cells and discuss the possibilities of cucurbitacin as a future anticancer drug in clinical settings.

Capsaicin causes cell-cycle arrest and apoptosis in ER-positive and -negative breast cancer cells by modulating the EGFR/HER-2 pathway

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is an ingredient of chili peppers with inhibitory effects against cancer cells of different origin. We examined the activity of capsaicin on breast cancer cells in vitro and in vivo. The drug potently inhibited growth of ER-positive (MCF-7, T47D, BT-474) and ER-negative (SKBR-3, MDA-MB231) breast cancer cell lines, which was associated with G(0)/G(1) cell-cycle arrest, increased levels of apoptosis and reduced protein expression of human epidermal growth factor receptor (EGFR), HER-2, activated extracellular-regulated kinase (ERK) and cyclin D1. In contrast, cell-cycle regulator p27(KIP1), caspase activity as well as poly-ADP ribose polymerase (PARP) cleavage were increased. Notably, capsaicin blocked breast cancer cell migration in vitro and decreased by 50% the size of MDA-MB231 breast cancer tumors growing orthotopically in immunodeficient mice without noticeable drug side effects. in vivo activation of ERK was clearly decreased, as well as expression of HER-2 and cyclin D1, whereas caspase activity and PARP cleavage products were increased in tumors of drug-treated mice. Besides, capsaicin potently inhibited the development of pre-neoplastic breast lesions by up to 80% without evidence of toxicity. Our data indicate that capsaicin is a novel modulator of the EGFR/HER-2 pathway in both ER-positive and -negative breast cancer cells with a potential role in the treatment and prevention of human breast cancer.

Cucurbitacin B induces apoptosis by inhibition of the JAK/STAT pathway and potentiates antiproliferative effects of gemcitabine on pancreatic cancer cells

Pancreatic cancer is an aggressive malignancy that is generally refractory to chemotherapy, thus posing experimental and clinical challenges. In this study, the antiproliferative effect of the triterpenoid compound cucurbitacin B was tested in vitro and in vivo against human pancreatic cancer cells. Dose-response studies showed that the drug inhibited 50% growth of seven pancreatic cancer cell lines at 10(-7) mol/L, whereas clonogenic growth was significantly inhibited at 5 x 10(-8) mol/L. Cucurbitacin B caused dose- and time-dependent G(2)-M-phase arrest and apoptosis of pancreatic cancer cells. This was associated with inhibition of activated JAK2, STAT3, and STAT5, increased level of p21(WAF1) even in cells with nonfunctional p53, and decrease of expression of cyclin A, cyclin B1, and Bcl-XL with subsequent activation of the caspase cascade. Interestingly, the combination of cucurbitacin B and gemcitabine synergistically potentiated the antiproliferative effects of gemcitabine on pancreatic cancer cells. Moreover, cucurbitacin B decreased the volume of pancreatic tumor xenografts in athymic nude mice by 69.2% (P < 0.01) compared with controls without noticeable drug toxicities. In vivo activation of JAK2/STAT3 was inhibited and expression of Bcl-XL was decreased, whereas caspase-3 and caspase-9 were up-regulated in tumors of drug-treated mice. In conclusion, we showed for the first time that cucurbitacin B has profound in vitro and in vivo antiproliferative effects against human pancreatic cancer cells, and the compound may potentate the antiproliferative effect of the chemotherapeutic agent gemcitabine. Further clinical studies are necessary to confirm our findings in patients with pancreatic cancer.

Characterisation of extramedullary relapse in patients with chronic myeloid leukemia in advanced disease after allogeneic stem cell transplantation

Recently, higher extramedullary relapse rates following allogeneic stem cell transplantation (SCT) in myeloid malignancies were reported e.g. because of selection of poor-risk patients. We analysed five consecutive patients with post-transplant extramedullary relapse of chronic myeloid leukemia (CML) out of a total of 24 patients (21%) undergoing allo-SCT. All five patients with extramedullary relapse had clonal evolution and a history of blast phase (BP). In particular, 56% of the patients in BP had extramedullary relapse with no extramedullary relapse in patients with chronic/accelerated phase. Most frequent manifestation sites were the skeletal system, the muscles/subcutaneous tissue and the central nervous system. In one case chloroma was mimicking myositis of the lower limbs. Combined approaches were performed including irradiation (n = 4), chemotherapy (n = 2), IM (n = 2), dasatinib (n = 4), nilotinib (n = 1), a novel aurora-kinase-inhibitor (n = 1), donor lymphocytes (n = 2) or a second allo-SCT (n = 2). Transient response was achieved in one case, stable partial remissions in two cases, whereas two cases were refractory. Research should focus on prospective studies aiming to improve treatment of extramedullary relapse in stem cell recipients with CML with a special focus on the role of second generation tyrosine kinase inhibitors.

Esophageal squamous cell carcinoma presenting with extensive skin lesions: a case report

Introduction

Esophageal squamous cell carcinoma (ESCC) is the most common histological subtype of cancer in the upper and middle esophagus and is characterized by a high rate of mortality. The incidence of esophageal cancer varies greatly among regions of the world and occurs at a high frequency in Asia and South America.

Case presentation

In our department, a 51-year-old man was diagnosed with ESCC after presenting with extensive disseminated skin nodules. Biopsy of the nodules showed metastatic ESCC. Cutaneous manifestations of esophageal neoplasia are very rare and are mainly described for esophageal adenocarcinoma (EADC). Here we report a very uncommon case of extensive skin metastases of ESCC.

Conclusion

Early biopsies of suspicious skin lesions are important and should be performed in patients with unclear symptoms such as weight loss or dysphagia and especially in patients with a history of cancer, since they can reveal the existence of a distant malignant disease leading to diagnosis and prompt therapy.