[Combination of phage display and SEREX for screening early lung cancer associated antigens].

OBJECTIVE: To screen out effective lung cancer associated antigens for early diagnosis in order to improve the level of early diagnosis. METHODS: A T7 phage display cDNA library of human early lung cancer was developed. And then differential phage clones were picked out to be sequenced and bioinformatically analyzed. With the 8 screened differential phage clones a lung cancer associated antigen microarray was established to evaluate the single or combined roles of all the selected antigens in the diagnosis of lung cancer by the reaction of the antigens plus serum from normal subjects and patients with lung cancer, respectively. RESULTS: The titer of the constructed cDNA library was 3.71×10 (6); pfu/ml and the number of phage was 1.11×10 (6); pfu, with a recombination rate of cDNA library over 90%. Nine differential phage clones were initially screened out, but the genes of two antigens (A42 and A83) were found the same. Bioinformatics analyses showed that the genes of the 8 antigens were known before and they were all proven to be related with tumor except A64. The positive reaction rates of the 8 antigens with serum from lung cancer patients were significantly higher than that with serum from normal subjects (Ps<0.05). When keeping specificity no less than 60%, the sensitivity of each antigen in predicting lung cancer alone was under 70% and the areas under curve (AUC) of the antigens were all under 0.8. However, when all the antigens were combined to detect lung cancer, the sensitivity and specificity was 90.8% and 94.1%, respectively, and AUC reached up to 0.969. CONCLUSION: A T7 phage display cDNA library with a good quality of capacity, recombination rate and representativeness of human early lung cancer was successfully developed, and 8 lung cancer associated antigens were screened out. A combination of the 8 antigens can greatly improve their value to diagnose lung cancer with a higher sensitivity and specificity (both above 90%)．

Effect of VEGF-targeted antisense gene therapy on retinoblastoma cell line SO-RB50 in vitro and in vivo.

AIM: To evaluate the possibility of generation 4 polyamidoamine (G4PAMAM) dendrimers acting as the delivery system of vascular endothelial growth factor (VEGF) antisense oligodeoxynucleotides (VEGFASODN), and to investigate the anti-tumor effect of G4PAMAM/VEGFASODN complex on the cultured cells and the mouse tumor xenograft model. METHODS: The transfection efficiency was assessed by Flow cytometry (FCM). Thiazolyl tetrazolium (MTT) assay was performed to determine the relative growth rate (RGR) of the cells after transfection. Then a mouse tumor xenograft model of human retinoblastoma was established. Different interventions were given to the mice by intratumoral injection and the tumor growth was monitored. The expression of VEGF mRNA was detected by reverse transcription PCR (RT-PCR), the expression of VEGF protein was determined by western blot analysis, and the microvessel density (MVD) was measured by immunohistochemistry (IHC) staining. RESULTS: G4PAMAM/VEGFASODN exhibited a high transfection rate in vitro, and the transfection rates of different doses of G4PAMAM/VEGFASODN groups increased with higher doses. This effect was accompanied by a dose-depended reduction in cell viability. The tumor growth in the tumor-bearing athymic mice was significantly inhibited in the G4PAMAM/VEGFASODN group. The expressions of VEGF mRNA and protein were obviously inhibited in the G4PAMAM/VEGFASODN group (P<0.05), and the MVD of the G4PAMAM/VEGFASODN group was lower than that of the other groups (P<0.05). CONCLUSION: VEGFASODN can be delivered into the cultured and transplanted retinoblastoma cells efficiently by G4PAMAM, suppress the expressions of VEGF mRNA and protein, and reduce the MVD of tumor tissues. The G4PAMAM/VEGFASODN complex has antitumor properties in vitro and in vivo.

Tumor stem cells: A new approach for tumor therapy (Review).

Recent studies have demonstrated the existence of a minority of tumor cells possessing the stem cell properties of self-renewal and differentiation in leukemia and several solid tumors. However, these cells do not possess the normal regulatory mechanisms of stem cells. Following transplantation, they are capable of initiating tumorigenesis and are therefore known as 'tumor stem cells'. Cellular origin analysis of tumor stem cells has resulted in three hypotheses: Embryonal rest hypothesis, anaplasia and maturation arrest. Several signaling pathways which are involved in carcinogenesis, including Wnt/ß-catenin, Notch and Oct-4 signaling pathways are crucial in normal stem cell self-renewal decisions, suggesting that breakdown in the regulation of self-renewal may be a key event in the development of tumors. Thus, tumors can be regarded as an abnormal organ in which stem cells have escaped from the normal constraints on self-renewal, thus, leading to abnormally differentiated tumor cells that lose the ability to form tumors. This new model for maligancies has significance for clinical research and treatment.