Thalidomide enhances the anti-tumor activity of standard chemotherapy in a human melanoma xenotransplatation model

Expression of the cereblon binding protein argonaute 2 plays an important role for multiple myeloma cell growth and survival

BACKGROUND

Immunomodulatory drugs (IMiDs), such as lenalidomide, are therapeutically active compounds that bind and modulate the E3 ubiquitin ligase substrate recruiter cereblon, thereby affect steady-state levels of cereblon and cereblon binding partners, such as ikaros and aiolos, and induce many cellular responses, including cytotoxicity to multiple myeloma (MM) cells. Nevertheless, it takes many days for MM cells to die after IMiD induced depletion of ikaros and aiolos and thus we searched for other cereblon binding partners that participate in IMiD cytotoxicity.

METHODS

Cereblon binding partners were identified from a MM cell line expressing histidine-tagged cereblon by pulling down cereblon and its binding partners and verified by co-immunoprecipitation. IMiD effects were determined by western blot analysis, cell viability assay, microRNA array and apoptosis analysis.

RESULTS

We identified argonaute 2 (AGO2) as a cereblon binding partner and found that the steady-state levels of AGO2 were regulated by cereblon. Upon treatment of IMiD-sensitive MM cells with lenalidomide, the steady-state levels of cereblon were significantly increased, whereas levels of AGO2 were significantly decreased. It has been reported that AGO2 plays a pivotal role in microRNA maturation and function. Interestingly, upon treatment of MM cells with lenalidomide, the steady-state levels of microRNAs were significantly altered. In addition, silencing of AGO2 in MM cells, regardless of sensitivity to IMiDs, significantly decreased the levels of AGO2 and microRNAs and massively induced cell death.

CONCLUSION

These results support the notion that the cereblon binding partner AGO2 plays an important role in regulating MM cell growth and survival and AGO2 could be considered as a novel drug target for overcoming IMiD resistance in MM cells.

Mechanisms of tumour vascularization in cutaneous malignant melanoma: clinical implications

Malignant melanoma represents < 10% of all skin cancers but is responsible for the majority of skin-cancer-related deaths. Metastatic melanoma has historically been considered as one of the most therapeutically challenging malignancies. Fortunately, for the first time after decades of basic research and clinical investigation, new drugs have produced major clinical responses. Angiogenesis has been considered an important target for cancer treatment. Initial efforts have focused primarily on targeting endothelial and tumour-related vascular endothelial growth factor signalling. Here, we review different mechanisms of tumour vascularization described in melanoma and discuss the potential clinical implications.

Mechanism of immunomodulatory drugs' action in the treatment of multiple myeloma

Although immunomodulatory drugs (IMiDs), such as thalidomide, lenalidomide, and pomalidomide, are widely used in the treatment of multiple myeloma (MM), the molecular mechanism of IMiDs' action is largely unknown. In this review, we will summarize recent advances in the application of IMiDs in MM cancer treatment as well as their effects on immunomodulatory activities, anti-angiogenic activities, intervention of cell surface adhesion molecules between myeloma cells and bone marrow stromal cells, anti-inflammatory activities, anti-proliferation, pro-apoptotic effects, cell cycle arrest, and inhibition of cell migration and metastasis. In addition, the potential IMiDs' target protein, IMiDs' target protein's functional role, and the potential molecular mechanisms of IMiDs resistance will be discussed. We wish, by presentation of our naive discussion, that this review article will facilitate further investigation in these fields.

Combination of dacarbazine and dimethylfumarate efficiently reduces melanoma lymph node metastasis

Dimethylfumarate (DMF) has been shown to reduce melanoma growth and metastasis in animal models. We addressed the question of whether DMF is as effective in its antitumor activity as the US Food and Drug Administration-approved alkylating agent dacarbazine (DTIC). We also tested the possibility of an improved antitumoral effect when both therapeutics were used together. Using our severe combined immunodeficiency (SCID) mouse model, in which xenografted human melanoma cells metastasize from primary skin sites to sentinel nodes, we show that these treatments, alone or in combination, reduce tumor growth at primary sites. Our main finding was that metastasis to sentinel nodes is significantly delayed only in mice treated with a combination of DTIC and DMF. Subsequent experiments were able to show that a combination of DTIC/DMF significantly reduced lymph vessel density in primary tumors as examined by real-time PCR and immunohistochemistry. In addition, DTIC/DMF treatment significantly impaired melanoma cell migration in vitro. In vivo, DTIC/DMF therapy significantly reduced mRNA expression and protein concentration of the promigratory chemokines CXCL2 and CXCL11. In addition, our data suggest that this xenotransplantation model is suitable for preclinical testing of various combinations of antimelanoma agents.

Thalidomide influences growth and vasculogenic mimicry channel formation in melanoma

AIMS

To observe the effects of thalidomide on melanoma tumor growth and blood supply patterns in C57 mice.

METHODS

Thirty mice inoculated subcutaneously with B16F10 cells were randomly divided into the treatment group and the control group. Thalidomide was administered once a day at a dose of 200 mg/kg for the treatment group starting on the fifth day after inoculation, and an equivalent volume of 0.5% carboxylmethyl cellulose was administered similarly in the control group. The diameter of the tumors was measured daily after inoculation until the mice were sacrificed on the 19th day. The different blood supply patterns were counted after immunohistochemical and PAS histochemical double-Staining. VEGF, NF-kappaB, PCNA, MMP-2 and MMP-9 expression in tumor tissue was also assessed.

RESULTS

The tumor volume(P = 0.019) and the number of vasculogenic mimicry(P = 0.03) and mosaic vessels(P = 0.004) in the treatment group were significantly decreased compared with the control group. VEGF(P = 0.004), NF-kappaB(P = 0.009), PCNA(P = 0.002), MMP-2 (P = 0.000), MMP-9(P = 0.002) protein expression and MMP-2(P = 0.000) and MMP-9(P = 0.000) mRNA in the treatment group were significantly lower than those in the control groups.

CONCLUSION

Thalidomide inhibits vasculogenic mimicry channel and mosaic vessels formation in melanoma through the regulation of vasculogenic factors, and it can induce necrosis of melanoma cells, which may be related with the NF-kappaB signaling pathway.

Tumor-targeting nanodelivery enhances the anticancer activity of a novel quinazolinone analogue

GMC-5-193 (GMC) is a novel anticancer small-molecule quinazolinone analogue with properties that include antimicrotubule activity and inherent fluorescence. The aim of this study was to produce and optimize a systemically administered liposomal formulation for tumor-targeting delivery of GMC to enhance the anticancer effect of this compound and evaluate its bioefficacy. GMC was encapsulated within a cationic liposome, which was decorated on the surface with an anti-transferrin receptor single-chain antibody fragment (TfRscFv) as the tumor-targeting moiety to form a nanoscale complex (scL/GMC). Confocal imaging of fluorescent GMC uptake in a human melanoma cell line, MDA-MB-435, showed higher cellular uptake of GMC when delivered via the liposome complex compared with free GMC. Delivery of GMC by the tumor-targeting liposome nanoimmunocomplex also resulted in a 3- to 4-fold decrease in IC(50) values in human cancer cells [DU145 (prostate) and MDA-MB-435] compared with the effects of GMC administered as free GMC. In addition, the GMC nanoimmunocomplex increased the sensitivity of cancer cells to doxorubicin, docetaxel, or mitoxantrone by approximately 3- to 30-fold. In the MDA435/LCC6 athymic nude mice xenograft lung metastases model, GMC was specifically delivered to tumors by the nanoimmunocomplex. These data show that incorporation of small-molecule therapeutic GMC within the tumor-targeting liposome nanocomplex enhances its anticancer effect.

A prospective randomized trial of thalidomide with topotecan compared with topotecan alone in women with recurrent epithelial ovarian carcinoma

BACKGROUND

Thalidomide is an antiangiogenic agent with immune modulating potential. The objective of this study was to determine response rates among women who were treated for recurrent ovarian cancer using topotecan with or without thalidomide.

METHODS

Women were enrolled in this multicenter, prospective, randomized phase 2 trial between April 2001 and July 2005. Eligible patients had recurrent epithelial ovarian carcinoma with measurable disease or elevated CA 125 values. Patients had received prior platinum-based chemotherapy. Treatment arms received topotecan at a dose of 1.25 mg/m(2) on Days 1 through 5 of a 21-day cycle with or without thalidomide starting at a dose of 200 mg per day and then increasing the dose as tolerated. Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria. The chi-square test was used to assess differences in response and toxicity, and the log-rank test was used to compare Kaplan-Meier survival curves.

RESULTS

The analysis included 69 women (39 women in the control arm and 30 women in the thalidomide arm). Known prognostic factors, including platinum sensitivity, were represented equally in each arm. The median thalidomide dose was 200 mg per day. The overall response rate in the control arm was 21% (complete response [CR] rate, 18%; partial response [PR] rate, 3%) compared with 47% in the thalidomide arm (CR rate, 30%; PR rate, 17%) (P= .03). The median progression-free survival for the control arm was 4 months compared with 6 months in the thalidomide arm (P= .02). The median overall survival was 15 months in the control arm and 19 months in the thalidomide arm (P= .67). Toxicities were similar between groups.

CONCLUSIONS

The addition of thalidomide to topotecan for the treatment of recurrent ovarian cancer appears to improve response rates, and the authors believe that it warrants study through larger phase 3 trials.

NF-kappaB as a molecular target in the therapy of pancreatic carcinoma

The constitutive activation of the transcription factor nuclear-factor kappa B (NF-kappaB) is a hallmark of many highly malignant tumours such as the pancreatic ductal adenocarcinoma and accounts for profound chemoresistance. Inhibition of NF-kappaB activation has been shown to be a useful strategy for increasing the sensitivity towards cytostatic drug treatment in vitro and in vivo. Moreover, various pharmacological substances (e.g. thalidomide, bortezomib, sulphasalazine) have already entered clinical studies partially showing promising results for certain types of cancer. Further studies will be needed, in particular for pancreatic ductal adenocarcinoma, to evaluate the therapeutic efficacy of appropriate combinations of a NF-kappaB inhibitor and cytostatic drugs.

Pathophysiologic Effects of Vascular-Targeting Agents and the Implications for Combination with Conventional Therapies

A functional vascular supply is critical for the continued growth and development of solid tumors. It also plays a major role in metastatic spread of tumor cells. This importance has led to the concept of targeting the vasculature of the tumor as a form of cancer therapy. Two major types of vascular-targeting agent (VTA) have now emerged: those that prevent the angiogenic development of the neovasculature of the tumor and those that specifically damage the already established tumor vascular supply. When used alone neither approach readily leads to tumor control, and so, for VTAs to be most successful in the clinic they will need to be combined with more conventional therapies. However, by affecting the tumor vascular supply, these VTAs should induce pathophysiologic changes in variables, such as blood flow, pH, and oxygenation. Such changes could have negative or positive influences on the tumor response to more conventional therapies. This review aims to discuss the pathophysiologic changes induced by VTAs and the implications of these effects on the potential use of VTAs in combined modality therapy.

Potentiation of cyclophosphamide chemotherapy using the anti-angiogenic drug thalidomide: importance of optimal scheduling to exploit the 'normalization' window of the tumor vasculature

The aim of this work was to study how administration schedule affects potentiation of cyclophosphamide, an alkylating agent, by thalidomide, an anti-angiogenic agent. Tumor oxygenation after thalidomide administration was determined over time by EPR oximetry. Such measurements provide a surrogate marker for determining the timing of 'normalization' of tumor vasculature. Re-growth delays were measured using different combinations and schedules of treatments. Additionally, the uptake of the metabolite of cyclophosphamide (hydroxycyclophosphamide or OH-CP) into tumors was determined by high performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A significant increase in pO(2) was observed after 2 and 3 days of treatment before eventually declining on day 4. Thalidomide potentiated the effect of cyclophosphamide only when cyclophosphamide was administered after 2 days of treatment with thalidomide (no significant benefit using other schedules). In this time frame, the HPLC/MS/MS measurements showed that the quantity of OH-CP penetrating into the tumor was about twice in mice treated by thalidomide compared to controls. In conclusion, the present study demonstrates that the benefit of combined therapy using an anti-angiogenic agent with a cytotoxic agent requires knowledge of the time window during which the vessels initially become normalized.