In vivo modulation of signaling factors involved in cell survival

Antioxidant activity of curcumin protects against the radiation-induced micronuclei formation in cultured human peripheral blood lymphocytes exposed to various doses of γ-Radiation

PURPOSE

Ionizing radiations trigger the formation of free radicals that damage DNA and cause cell death. DNA damage may be simply evaluated by micronucleus assay and the pharmacophores that impede free radicals could effectively reduce the DNA damage initiated by irradiation. Therefore, it was desired to determine the capacity of curcumin to alleviate micronuclei formation in human peripheral blood lymphocytes (HPBLs) exposed to 0-4 Gy of γ-radiation.

MATERIALS AND METHODS

HPBLs were exposed to 3 Gy after 30 minutes of 0.125, 0.25, 0.5, 1, 2, 5, 10, 20 or 50 µg/mL curcumin treatment or with 0.5 μg/mL curcumin 30 minutes early to 0, 0.5, 1, 2, 3 or 4 Gy 60Co γ-irradiation. Cytokinesis of HPBLs was blocked by cytochalasin B and micronuclei scored. The ability of curcumin to suppress free radical induction in vitro was determined by standard methods.

RESULTS

HPBLs treated with different concentrations of curcumin before 3 Gy irradiation alleviated the micronuclei formation depending on curcumin concentration and the lowest micronuclei were detected at 0.5 µg/mL curcumin when compared to 3 Gy irradiation alone. Increasing curcumin concentration caused a gradual rise in micronuclei, and the significant increases were detected at 10-50 µg/mL curcumin than 3 Gy irradiation alone. Irradiation of HPBLs to different doses of γ-rays caused a significant rise in micronuclei depending on radiation dose, whereas HPBLs treated with 0.5 µg/mL curcumin 30 minutes before irradiation to different doses of γ-rays significantly reduced frequencies of HPBLs with one, two, or more micronuclei. Curcumin treatment inhibited the formation of hydroxyl (OH), 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2'-diphenyl-1-picrylhydrazyl (DPPH), and (nitric oxide) NO free radicals in a concentration-related way.

CONCLUSIONS

Curcumin when treated at a dose of 0.5 μg/mL attenuated micronuclei formation after γ-irradiation by inhibiting the formation of radiation-induced free radicals.

Liposome-Encapsulated Curcumin-Loaded 3D Printed Scaffold for Bone Tissue Engineering

Curcumin, the active constituent for turmeric, is known for its antioxidant, anti-inflammatory, anticancer, and osteogenic activities. However, it shows extremely poor bioavailability, rapid metabolism, and rapid systemic elimination. In this study, we have increased the bioavailability of curcumin by encapsulating it in a liposome, followed by the incorporation onto 3D printed (3DP) calcium phosphate (CaP) scaffolds with designed porosity. 3DP scaffolds with a designed shape and interconnected porosity allow for the fabrication of patient-specific implants, providing new tissue ingrowth by mechanical interlocking between the surrounding host tissue and the scaffold. Upon successful encapsulation of curcumin into the liposomes, we have investigated the effect of liposomal curcumin released from the 3DP scaffolds on both human fetal osteoblast cells (hFOB) and human osteosarcoma (MG-63) cells. Interestingly, liposomal curcumin released from the 3DP scaffold showed significant cytotoxicity toward in vitro osteosarcoma (bone cancer) cells, whereas it promoted osteoblast (healthy bone cell) cell viability and proliferation. These results reveal a novel approach toward the fabrication of tissue engineering scaffolds, which couples the advanced additive manufacturing technology with the wisdom of alternative medicine. These bifunctional scaffolds eradicate the osteosarcoma cells and also promote osteoblast proliferation, offering new opportunities to treat bone defects after tumor resection.

Curcumin in various cancers

Curcumin (diferuloylmethane), an active constituent of turmeric, is a well-described phytochemical, which has been used since ancient times for the treatment of various diseases. The dysregulation of cell signaling pathways by the gradual alteration of regulatory proteins is the root cause of cancers. Curcumin modulates regulatory proteins through various molecular mechanisms. Several research studies have provided in-depth analysis of multiple targets through which curcumin induces protective effects against cancers including gastrointestinal, genitourinary, gynecological, hematological, pulmonary, thymic, brain, breast, and bone. The molecular mechanisms of action of curcumin in treating different types of cancers remain under investigation. The multifaceted role of this dietary agent is mediated through its inhibition of several cell signaling pathways at multiple levels. Curcumin has the ability to inhibit carcinogenicity through the modulation of the cell cycle by binding directly and indirectly to molecular targets including transcription factors (NF-kB, STAT3, β-catenin, and AP-1), growth factors (EGF, PDGF, and VEGF), enzymes (COX-2, iNOS, and MMPs), kinases (cyclin D1, CDKs, Akt, PKC, and AMPK), inflammatory cytokines (TNF, MCP, IL-1, and IL-6), upregulation of proapoptotic (Bax, Bad, and Bak) and downregulation of antiapoptotic proteins (Bcl(2) and Bcl-xL). A variety of animal models and human studies have proven that curcumin is safe and well tolerated even at very high doses. This study elaborates the current understanding of the chemopreventive effects of curcumin through its multiple molecular pathways and highlights its therapeutic value in the treatment and prevention of a wide range of cancers.

EMMPRIN expression as a prognostic factor in radiotherapy of cervical cancer

PURPOSE

Overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN), a member of the immunoglobulin family and a glycoprotein enriched on the surface of many types of tumor cells, has been reported to be linked to invasion, metastasis, growth, and survival of malignant cells. Cervical cancer, the second most prevalent cancer in women worldwide and the fifth leading cause of cancer deaths, responds to radiotherapy variably, with 30% of cases recurring after therapy. The purpose of this study was to determine whether expression of EMMPRIN affects the response of cervical cancer to radiation therapy, and whether this membrane protein can be used as a prognostic marker for cervical cancer.

EXPERIMENTAL DESIGN

The retrospective cohort study included 82 patients with invasive cervical cancer referred to the Department of Gynecologic Oncology at The Cancer Hospital of Fudan University (Shanghai) between 1991 and 2000. These patients were treated with brachytherapy at a dose of 15 Gy at point A before radical hysterectomy. Expression of EMMPRIN in cervical tumor specimens was examined by immunohistochemistry staining before and after brachytherapy and scored for both staining intensity and percentage of tumor cells stained. EMMPRIN immunoreactivity and clinicopathologic data were analyzed with respect to survival end points using univariate and multivariate approaches.

RESULTS

The frequency of EMMPRIN overexpression was 52.4% in primary cervical cancer. After brachytherapy, EMMPRIN overexpression was significantly reduced (13.4%) compared with corresponding tumor before brachytherapy (P = 0.032). EMMPRIN expression was associated with pelvic lymph node metastasis (P = 0.026) and reduction in primary tumor volume following brachytherapy (P = 0.008). Although EMMPRIN expression before or after brachytherapy did not correlate with tumor-specific survival, but increased expression of EMMPRIN following brachytherapy tended to predict poor outcomes by univariate survival analysis (P = 0.0008). In addition, lymph vascular space invasion, deep stromal invasion, and lymph node metastasis were significantly associated with poor prognosis. In multivariate analysis, the independent prognostic factors for tumor-specific survival included the decreased expression of EMMPRIN after brachytherapy (P = 0.002; hazard ratio, 0.339; 95% confidence interval, 0.172-0.672) as well as lymph node metastasis (P = 0.044; hazard ratio, 2.053; 95% confidence interval, 1.020-4.133).

CONCLUSION

Expression of EMMPRIN was associated with a decrease in the reduction of cervical tumor following brachytherapy, and increased EMMPRIN expression after brachytherapy seemed to be an important predictor of poor survival in this patient cohort. Our study suggests that expression of EMMPRIN confers resistance to radiotherapy. Therefore, EMMPRIN expression in cervical cancer may be regarded both as a prognostic factor and a therapeutic target.

Cyclic nucleotide Response Element Binding protein (CREB) activation promotes survival signal in human K562 erythroleukemia cells exposed to ionising radiation/etoposide combined treatment

Anticancer therapy addresses the destruction of tumour cells which try to counteract the effect of drugs and/or ionising radiation. Thus the knowledge of the threshold over which the cells do not resist such agents could help in the setting up of therapy protocols. Since a key role was assigned to Cyclic nucleotide Response Element Binding protein (CREB) multigenic family (which is composed of several nuclear transcription factors involved in c-AMP signalling in cell differentiation, proliferation, apoptosis, survival and adaptive response and in hematopoiesis and acute leukemias), attention was paid to the activation of Erk cascade and of the downstream kinases and transcription factors such as p90RSK and CREB. K562 erythroleukemia cell survival to 1.5 Gy ionising radiation with or without etoposide treatment seemed to involve Erk phosphorylation which, regulating p90 RSK, should activate CREB. In parallel, p38 MAP kinase activity down-modulation, along with low caspase-3 activity, and no modification of Bax and Bcl2 levels, supported such evidence. Thus, endogenous CREB activation, triggering a potent survival signal in K562 cells exposed to 1.5 Gy with or without etoposide, led us to suggest that using specific inhibitors against CREB, such as modified phosphorothionate oligodeoxynucleotides (ODN) corresponding to CREB-1 sequence, anticancer therapy efficacy could be improved.

Inhibition of radiation induced nitration by curcumin and nicotinamide in mouse macrophages

Nitric oxide plays an important role in inflammation and carcinogenesis and has now been implicated as an important signaling molecule under normal physiological conditions also. Increased nitric oxide (NO) results in increased nitration of proteins at tyrosine, which can cause protein dysfunction or alterations in signal transduction pathways. Irradiation of Lipopolysaccharide (LPS) activated mouse peritoneal macrophages was found to increase NO production, inducible nitric oxide synthase (iNOS) expression and nitration of proteins. The increase in iNOS expression was very less when compared to increase in NO production, indicating the possibility of post-translational activation of iNOS by LPS and ionising radiation. The addition of curcumin, nicotinamide and Jun N-terminal kinase (JNK) inhibitor, SP 600125, reduced the levels of NO, iNOS expression and nitration of proteins in macrophages. Closer scrutiny of the inhibition pattern of these modulators revealed that although the JNK inhibitor did not result in significant decrease in iNOS expression it led to a significant decrease in NO production, implying the possible involvement of JNK in the regulation of iNOS activity. Curcumin and JNK inhibitor directly inhibited the nitration of proteins and JNK inhibitor and curcumin, when added together, did not show synergistic effect.