Cyclin D1 belongs to a family of proteins that regulate progression through the G 1 -S phase of the cell cycle by binding to cyclin-dependent kinase (cdk)-4 to phosphorylate the retinoblastoma protein and release E2F transcription factors for progression through cell cycle. Several cancers, including breast, colon, and prostate, overexpress the cyclin D1 gene. However, the correlation of cyclin D1 overexpression with E2F target gene regulation or of cdk-dependent cyclin D1 activity with tumor development has not been identified. This suggests that the role of cyclin D1 in oncogenesis may be independent of its function as a cell cycle regulator. One such function is the role of cyclin D1 in cell adhesion and motility. Filamin A (FLNa), a member of the actin-binding filamin protein family, regulates signaling events involved in cell motility and invasion. FLNa has also been associated with a variety of cancers including lung cancer, prostate cancer, melanoma, human bladder cancer, and neuroblastoma. We hypothesized that elevated cyclin D1 facilitates motility in the invasive MDA-MB-231 breast cancer cell line. We show that MDA-MB-231 motility is affected by disturbing cyclin D1 levels or cyclin D1-cdk4/6 kinase activity. Using mass spectrometry, we find that cyclin D1 and FLNa coimmunoprecipitate and that lower levels of cyclin D1 are associated with decreased phosphorylation of FLNa at Ser2152 and Ser1459. We also identify many proteins related to cytoskeletal function, biomolecular synthesis, organelle biogenesis, and calcium regulation whose levels of expression change concomitant with decreased cell motility induced by decreased cyclin D1 and cyclin D1-cdk4/6 activities.

Angiogenesis is critical to the growth and metastasis of solid tumors, and acquired drug resistance is one of the major hindrances to chemotherapy. Thus, we sought a rational strategy using the combination of antiangiogenic biotherapy and chemotherapy for cancer therapy. We explored the efficacy of a strategy combining low-dose cisplatin and a recombinant xenogeneic endoglin as a protein vaccine, which we previously demonstrated to have effective antiangiogenic effects in several mouse models. We found that both lowdosage cisplatin and xenogeneic endoglin vaccine individually resulted in effective suppression of tumor growth in 2 tumor models via inhibition of tumor angiogenesis. Remarkably, the combination therapy resulted in not only significant antiangiogenic effects but also additional promotion of tumor cell apoptosis and inhibition of tumor cell proliferation, without any ensuing increase in host toxicity during the course of treatment, which lasted for 6 months. In addition, the combination demonstrated a synergistic relationship, which was shown in all of the synergistic indexes, i.e., tumor volume, angiogenesis, apoptosis and proliferation. Both antibodies and antibody-producing B cells against mouse self-endoglin were observed in all mice immunized by the xenogeneic endoglin vaccine (alone and combination), which suggested that low-dose cisplatin did not suppress the host immune response but potentiated the antitumor activity of the xenogeneic endoglin vaccine. These observations may provide the basis for an effective alternative strategy for cancer therapy in the near future.

Key words: apoptosis; vesicular stomatitis virus; gemcitabine; lung cancer; chemotherapyLung cancer accounts for about 1.5 million cases worldwide and is the leading cause of cancer-related death in both males and females. Non small cell lung cancer (NSCLC) comprises approximately 75-80% of all lung cancers. Despite aggressive approaches made in the therapy of lung cancer in the past decades, the prognosis of NSCLC remains poor, with 5-year survival rates of 5-14%, even if treated with surgery, radiotherapy and/or chemotherapy. 1-3 Efforts are therefore continuing to develop new and less toxic therapeutic approaches for the treatment of lung cancer.Vesicular stomatitis virus (VSV) is an enveloped, negativesense RNA virus and prototypic member of the family rhabdoviridae. 4 -6 It has been shown to replicate rapidly in vitro and kill selectively a variety of tumor cell lines. An essential, dose-limiting site of chemotherapy is the bone marrow while VSV can selectively kill leukemia cells when cocultured with normal bone marrow cells. 4 Furthermore, VSV exhibits the antitumor activity in both human tumor xenografts in nude mice and syngeneic tumors in the immunocompetent mice. 4,5 Gemcitabine (2Ј,2Ј-diflurodeoxycytidine) is a new deoxycytidine analogue that inhibits DNA synthesis. After cellular uptake, gemcitabine is phosphorylated to its active metabolites, which competitively inhibits DNA chain elongation, leading to DNA fragmentation and cell death. Gemcitabine has shown cytotoxic activity against a wide range of cancer cell lines in vitro and a number of murine and human tumors in vivo. [7][8][9] Gemcitabine monotherapy produced objective response in 20 -25% of patients with advanced NSCLC and has similar efficacy to cisplatin plus etoposide. 10 -12 When combined with cisplatin and/or paclitaxel or vinorelbine, gemcitabine therapy shows an objective response rates in 28 -54% and the median survival durations ranged from 38 to 61.5 weeks. [13][14][15][16][17][18] However, the treatment of advanced lung cancer still remains a challenge to medical oncologists.Because of differences in mechanisms of action and toxicity profiles, the combination of the above 2 agents may have clinical potential. The present study was designed to determine whether gemcitabine potentiates the antitumor activity of VSV in vitro using both A549 (human lung adenocarcinoma) and LLC (murine Lewis lung carcinoma) cell lines and in vivo using A549 lung cancer xenografts and the murine syngeneic Lewis lung cancer, and if so, to examine the possible mechanism in the phenomenon, as well as to provide some potential implications for the treatment of human lung cancer. MATERIAL AND METHODS Cells lines and agentsLLC cells and A549 cells were purchased from American Type Culture Collection (Rockville, MD). They were maintained in monolayer cultures in DMEM and RPMI-1640, respectively, supplemented with 10% heat-inactivated fetal bovine serum (FBS), at 37°C in a humidified atmosphere containing 5% CO 2 . Human umbilical vein endothelial cells (HU...

No abstract