This study was aimed to investigate the biological characteristics of osteoblasts from patients with myelodysplastic syndrome (MDS) and their supportive capacity for hematopoiesis in vitro. A two-dimensional culture system was constructed by using osteoblasts derived from human marrow mesenchymal stem cells (MSC); MSCs were isolated from bone marrow of MDS patients and normal individuals and were cultured; the third passage of MSCs were induced into osteoblasts which were treated with mitomycin C and confluenced into a feeder layer. Ficolled bone marrow mononuclear cells were obtained from normal individuals and seeded into the two-dimensional culture system to culture in vitro without exogenous cytokines. By using colony-forming assay, the ability of the two-dimensional system to culture HPCs was observed. The cytokine expression of osteoblasts from MDS patient bone marrows in mRNA level was detected by RT-PCR and was compared with human osteoblast cell line hFOB1.19. The results showed that the osteoblasts from MDS patients could support short-term survival of GM-CFC in condition without exogenous cytokines, that is, osteoblasts played a crucial role in regulation of HPC growth. The results of RT-PCR clearly demonstrated that the osteoblast cell line hFOB1.19 expressed SCF, IL-6, SDF-1alpha, G-CSF and GM-CSF. The same expression patterns of above cytokines were also seen in osteoblasts derived from BM-MSCs of MDS patients and normal individuals, but these cells did not express GM-CSF. It is concluded that the biological characteristics of osteoblasts from bone marrow of MDS patients are generally not different from those of osteoblasts from normal bone marrow. Both of them can support GM -CFC to form colonies in vitro, it may be associated with expressing important related cytokines by osteoblasts.
Cytokines ; metabolism ; Granulocyte-Macrophage Colony-Stimulating Factor ; metabolism ; Granulocyte-Macrophage Progenitor Cells ; cytology ; Hematopoietic Stem Cells ; cytology ; Humans ; Interleukin-6 ; metabolism ; Myelodysplastic Syndromes ; metabolism ; pathology ; Osteoblasts ; metabolism ; physiology ; RNA, Messenger ; metabolism ; Stem Cell Factor ; metabolism

OBJECTIVETo compare the CC-chemokine ligand 18 (CCL18) expression in the serum and malignant pleural effusion (MPE) of NSCLC patients and explore its regulatory effect on differentiation of monocyte-derived dendritic cells (Mo-DC).

METHODSCCL18 levels in the serum and MPE from 62 NSCLC patients were quantitated by immunoassay. CCL18 in sera from 26 healthy individuals, 28 exudative pleural effusions from inflammatory pulmonary diseases and 17 transudative pleural effusions from non-inflammatory diseases were used as control. Mo-DC was generated by culturing NSCLC-derived monocytes with GM-CSF and IL-4 in the presence or absence of CCL18. The mean fluorescent intensity (MFI) of CD14, CD80, CD83, CD86 and HLA-DR were analyzed by flow cytometry (FCM). Mo-DC was then co-cultured with purified T cells and the percence of CD25(+)FoxP3(+) cells was assayed by FCM.

RESULTSCCL18 levels in the sera of NSCLC patients and healthy individuals were (132.70 ± 15.52) ng/ml and (18.44 ± 0.99) ng/ml, respectively (P < 0.001). The levels of CCL18 in MPE, exudative PE and transudative PE were (155.6 ± 13.58) ng/ml, (190.4 ± 22.33) ng/ml and (20.89 ± 3.03) ng/ml, respectively. CCL18 in the MPE was significantly higher than that in transudates (P < 0.001), however, no significant difference was observed between CCL18 expression in exudative PE and MPE (P = 0.172). Of note, a moderate positive correlation (r = 0.421, P < 0.01) was observed between CCL18 levels in the paired MPE and serum of NSCLC. In the healthy control group, Mo-DC cultured in the presence of CCL18 showed 31.4 ± 15.8 (MFI) of CD14 expression, which was significantly higher than that in Mo-DC cultured in the absence of CCL18 (18.5 ± 8.9, P < 0.05). In contrast, the expressions of MFI of CD80, CD83, CD86 and HLA-DR were significantly decreased upon CCL18 induction (P < 0.05). In the NSCLC group, GM-CSF+IL-4+CCL18 induced a MFI of 45.2 ± 13.8 of CD14 expression in Mo-DC, which was also significantly higher than that of GM-CSF+ IL-4 induction (22.6 ± 10.5, P < 0.01). Similarly, the expressions of MFI of CD80, CD83, CD86 and HLA-DR were significantly decreased in the presence of CCL18 (P < 0.05). Furthermore, the MFI of CD14, CD83, CD86 and HLA-DR had significant differences between GM-CSF/IL-4/CCL18-induced Mo-DC derived from NSCLC patients and healthy control (P < 0.05). Finally, CD4(+) T cells co-cultured with NSCLC-derived, GM-CSF/IL-4/CCL18-treated Mo-DC had significantly higher percent of CD25(+)FoxP3(+) cells compared with that of CD4(+) T cells stimulated with Mo-DC induced by GM-CSF/IL-4(P < 0.01).

CONCLUSIONSCCL18 is present at a high level in MPE and serum of NSCLC patients complicated with pleural effusion and a moderate positive correlation exists between CCL18 levels in the two fluids. CCL18 inhibits maturation of Mo-DC, which consequently stimulates T cells to differentiate into CD25(+)FoxP3(+) regulatory T cells.

Carcinoma, Non-Small-Cell Lung ; metabolism ; Cell Differentiation ; Chemokines ; Chemokines, CC ; metabolism ; Coculture Techniques ; Dendritic Cells ; metabolism ; Flow Cytometry ; Granulocyte-Macrophage Colony-Stimulating Factor ; metabolism ; Humans ; Interleukin-4 ; metabolism ; Ligands ; Lung Neoplasms ; Monocytes ; physiology ; Pleural Effusion ; T-Lymphocytes, Regulatory

OBJECTIVE: To observe the effect of wheat-grain moxibustion at "Dazhui" (GV 14), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6) on Wnt/β-catenin signaling pathway in bone marrow cell in mice with bone marrow inhibition, and to explore the possible mechanism of wheat-grain moxibustion in treating bone marrow inhibition. METHODS: Forty-five SPF male CD1(ICR) mice were randomly divided into a blank group, a model group and a wheat-grain moxibustion group, 15 mice in each group. The bone marrow inhibition model was established by intraperitoneal injection of 80 mg/kg of cyclophosphamide (CTX). The mice in the wheat-grain moxibustion group were treated with wheat-grain moxibustion at "Dazhui" (GV 14), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), 3 moxa cones per acupoint, 30 s per moxa cone, once a day, for 7 consecutive days. The white blood cell count (WBC) was measured before modeling, before intervention and 3, 5 d and 7 d into intervention. After intervention, the general situation of mice was observed; the number of nucleated cells in bone marrow was detected; the serum levels of interleukin-3 (IL-3), interleukin-6 (IL-6) and granulocyte macrophage colony stimulating factor (GM-CSF) were measured by ELISA; the protein and mRNA expression of β-catenin, cyclinD1 and C-Myc in bone marrow cells was measured by Western blot and real-time PCR method. RESULTS: Compared with the blank group, the mice in the model group showed sluggish reaction, unstable gait, decreased body weight, and the WBC, number of nucleated cells in bone marrow as well as serum levels of IL-3, IL-6, GM-CSF were decreased (P<0.01), and the protein and mRNA expression of β-catenin, cyclinD1 and C-Myc was decreased (P<0.01). Compared with the model group, the mice in the wheat-grain moxibustion group showed better general condition, and WBC, the number of nucleated cells in bone marrow as well as serum levels of IL-3, IL-6, GM-CSF were increased (P<0.01, P<0.05), and the protein and mRNA expression of β-catenin, cyclinD1 and C-Myc was increased (P<0.05). CONCLUSION Wheat-grain moxibustion shows therapeutic effect on bone marrow inhibition, and its mechanism may be related to activating Wnt/β-catenin signaling pathway in bone marrow cells, improving bone medullary hematopoiesis microenvironment and promoting bone marrow cell proliferation.
Animals ; Male ; Mice ; beta Catenin/metabolism* ; Bone Marrow/physiopathology* ; Bone Marrow Cells/physiology* ; Granulocyte-Macrophage Colony-Stimulating Factor/metabolism* ; Interleukin-3/metabolism* ; Interleukin-6/metabolism* ; Mice, Inbred ICR ; Moxibustion/methods* ; RNA, Messenger/metabolism* ; Triticum ; Wnt Signaling Pathway ; Hematopoiesis

Uncontrolled cell proliferation is the basic feature of cancer. Some of the prime cell cycle regulators are involved directly in tumorigenesis. Cyclin A, one of the G(1)/S cyclin, can cause transformation. The purpose of this research was to investigate whether cyclin A overexpression was involved in leukemogenesis and proliferation of leukemia cells. The expression of cyclin A at S-phase in leukemia cell line HL-60, blast cells of acute leukemia patients, bone marrow cells of outpatients without malignant hematological disease and peripheral blood cells of healthy donors was investigated by simultaneous indirect immunofluorescence staining of intracellular antigen and DNA. To further investigate whether cyclin A played as a key molecular in cell proliferation, HL-60 cells were exposed to different concentrations of hexamethylene bisacetamide (HMBA). MTT dye absorbance of living cells and cell cycle analysis were adopted to evaluate growth arrest. Differentiation was evaluated by detection of the change of expression of CD11b and CD33 on cell surface. The results showed that overexpression of cyclin A was only found among specimens from acute leukemia and leukemia cell line. There was no elevated cyclin A detection for cyclin A among specimens from outpatients and healthy donors. In HMBA interference experiment, HMBA was able to induce growth arrest and monocytic macrophage differentiation of HL-60 cells in a dose-dependent manner, and all these changes were associated with a marked down-regulation of cyclin A expression. In conclusion, aberrant overexpression of cyclin A at S-phase was only found in leukemia cell lines and blast cells from acute leukemia. The dose-dependent effect of HMBA on cell growth and differentiation of HL-60 cell line which was consistent with the decrease of cyclin A expression in these cells suggested that the molecular mechanisms of HMBA inducement involved downregulation of cyclin A expression.
Acetamides ; pharmacology ; Acute Disease ; Adolescent ; Adult ; Aged ; Cell Differentiation ; drug effects ; Cell Division ; drug effects ; Cyclin A ; analysis ; physiology ; Female ; Granulocyte-Macrophage Colony-Stimulating Factor ; pharmacology ; HL-60 Cells ; Humans ; Immunohistochemistry ; Leukemia ; metabolism ; pathology ; Male ; Middle Aged

Granulocyte macrophage-colony stimulating factor (GM-CSF) has immuno-stimulatory effects. We hypothesized that GM-CSF plays an important role both in lipopolysaccharide (LPS)- and hemorrhage-induced acute lung injury (ALI). We also postulated that GM-CSF augments LPS-induced inflammation by priming neutrophils. ALI was induced in GM-CSF-/- or control C57BL mice either by LPS injection or by hemorrhage. Lung inflammation (by lung expression for tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-2 (MIP-2), interleukin-1beta (IL-1beta), interleukin- 6 (IL-6), and keratinocyte-derived chemokine) and lung injury (by myeloperoxidase and evans blue dye assay) were evaluated after ALI. Incremental doses of LPS (0, 1, 10, and 100 ng/mL) and GM-CSF (0, 1, 10, and 100 ng/mL) were added to bone marrow neutrophils. The expression of TNF-alpha, MIP-2, and IL-1beta was evaluated with enzyme linked immunosorbent assay. The mRNA expression of three cytokines, and the nuclear translocation of nuclear factor kappa B (NF kappa-B) were evaluated by reverse transcriptase-polymerase chain reaction and electropnoretic mobility shift assay, respectively. GM-CSF -/- mice showed decreased neutrophil infiltration, less leakage, and lower expression of cytokines in the lung after LPS or hemorrhage. GM-CSF augmented LPS-induced protein and mRNA expression of TNF-alpha, MIP-2 and IL-1beta, which was mediated by increased intra-nuclear translocation of NF-kappa B. GM-CSF plays an important role in high-dose LPS and hemorrhage-induced ALI, which appears to be mediated by its priming effect on neutrophils.
Animals ; Bone Marrow Cells/cytology ; Chemokine CXCL2/metabolism ; Granulocyte-Macrophage Colony-Stimulating Factor/metabolism/*physiology ; Interleukin-1beta/metabolism ; Lipopolysaccharides/metabolism ; Lung/metabolism/pathology ; *Lung Injury ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mice, Transgenic ; Neutrophils/*cytology/metabolism ; Peroxidase/metabolism ; Tumor Necrosis Factor-alpha/metabolism

OBJECTIVETo investigate the phosphorylation intensity of MAPK pathway molecular Erk1/2 and the proliferation of prostate cancer cell line PC-3M.

METHODSFlow cytometry and RT-PCR were employed to study the ratio of different cell cycles and phases, respectively, before and after GM-CSF stimulation. Erk1/2 phosphorylation intensity was examined by Western blot simultaneously.

RESULTSThe rate of PC-3M cells at S and G2/M stages and the expression intensity of Ki-67 increased after GM-CSF incubation in a dose-dependent manner. The phosphorylation intensity of Erk1/2 increased remarkably after stimulation with GM-CSF.

CONCLUSIONThe intensification of Erk1/2 phosphorylation is one important molecular mechanism of the proliferation of hormone-independent prostate cancer.

Cell Line, Tumor ; Cell Proliferation ; Granulocyte-Macrophage Colony-Stimulating Factor ; pharmacology ; Humans ; Ki-67 Antigen ; biosynthesis ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; physiology ; Neoplasms, Hormone-Dependent ; metabolism ; pathology ; physiopathology ; Phosphorylation ; Prostatic Neoplasms ; metabolism ; pathology ; physiopathology ; Signal Transduction ; drug effects

OBJECTIVETo explore the formation of pre-metastatic niche in the mouse lung and to study the underlying molecular mechanisms whereby primary breast carcinoma-derived factors mediate recruitment of bone marrow-derived cells (BMDCs) and affect the formation of pre-metastatic lung environment before the arrival of tumor cells.

METHODSMammary carcinoma 4T1 cells were inoculated into the mammary gland to construct mouse model of breast cancer. Confocal microscopy was used to detect the recruitment of BMDCs in the pre-metastatic lungs. The expression of factors in the mouse sera and 4T1 cell culture media was assayed using RayBio Custom mouse cytokine antibody array kit. The mice were injected daily with recombinant VEGF for 7 consecutive days to observe the effect of VEGF on BMDCs recruitment in the mouse lung.

RESULTSNo BMDCs were observed in the lungs of control and 4T1-tumor-bearing mice on day 0. On day 7 and 14, clusters of BMDCs observed in the lungs of 4T1-tumor-bearing mice were 8.7±2.2/objective field and 48.8±3.2/objective field, respectively, significantly higher than those in the control mice (1.1±0.8/objective field and 3.1±1.7/objective field) (P<0.05 for both). Confocal microscopic observation found that metastatic breast cancer cells preferentially facilitate BMDCs recruitment sites in the pre-metastatic mouse lungs. The levels of VEGF, GM-CSF, and IL-6 in the serum of 4T1-tumor-bearing mice were significantly increased compared with those in the control group (P<0.05 for all). However, VEGF was detected only in the culture media of 4T1 cells. The amount of BMDCs in the mouse lung tissue was (22.8±3.6)/objective field in the VEGF group and (3.1±0.4)/objective field in the control group (P<0.05). There were 36.8±5.4 metastatic foci in the lung tissue of VEGF group and 12.6±2.2 in the control group (P<0.05).

CONCLUSIONSThe results of this study demonstrate that primary breast cancer cells can alter the lung microenvironment during the pre-metastatic phase and induce the formation of pre-metastatic niche. Primary tumor cell-derived VEGF may be a crucial factor responsible for the formation of pre-metastatic niche.

Animals ; Bone Marrow Cells ; Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Disease Models, Animal ; Female ; Granulocyte-Macrophage Colony-Stimulating Factor ; blood ; Humans ; Interleukin-6 ; blood ; Lung ; pathology ; Lung Neoplasms ; secondary ; Mice ; Recombinant Proteins ; administration & dosage ; Time Factors ; Tumor Microenvironment ; Vascular Endothelial Growth Factor A ; administration & dosage ; physiology ; secretion

OBJECTIVEThe aim of this study was to construct a new oncolytic virus oHSV2hGM-CSF and evaluate its oncolytic activity in vitro and in vivo in parallel with oHSV1hGM-CSF.

METHODSoHSV2hGM-CSF was a replication-competent, attenuated HSV2 based on the HG52 virus (an HSV2 strain). It was engineered to be specific for cancer by deletion of the viral genes ICP34.5 and ICP47 and insertion of the gene encoding hGM-CSF. To measure the in vitro killing effect of the virus, 15 human tumor cell lines (HeLa, Eca-109, PG, HepG2, SK/FU, CNE-2Z, PC-3, SK-OV3, A-549, 786-0, MCF-7, Hep-2, HT-29, SK-Mel-28, U87-MG) and mouse melanoma (B16R) cell line were seeded into 24-well plates and infected with viruses at MOI = 1 (multiplicity of infection, MOI), or left uninfected. The cells were harvested 24 and 48 hours post infection, and observed under the microscope. For animal studies, the oncolytic viruses were administered intratumorally (at 3-day interval) at a dose of 2.3 x 10(6) PFU (plaque forming unit, PFU) for three times when the tumor volume reached 7-8 mm3. The tumor volume was measured at 3-day intervals and animal survival was recorded.

RESULTSBoth oHSV2hCM-CSFand oHSV1hGM-CSF induced widespread cytopathic effects at 24 h after infection. OHSV2hGM-CSF, by contrast, produced more plaques with a syncytial phenotype than oHSV1hGM-CSF. In the in vitro killing experiments for the cell lines HeLa, HepG2, SK-Mel-28, B16R and U87-MG, oHSV2hGM-CSF eradicated significantly more cells than oHSV1hGM-CSF under the same conditions. For the mouse experiments, it was observed that oHSV2hGM-CSF significantly inhibited the tumor growth. At 15 days after B16R tumor cells inoculation, the tumor volumes of the PBS, oHSV1hGCM-CSF and oHSV2hGM-CSF groups were (374.7 +/- 128.24) mm3, (128.23 +/- 45.32) mm3 (P < 0.05, vs. PBS group) or (10.06 +/- 5.1) mm3 (P < 0.01, vs. PBS group), respectively (mean +/- error). The long term therapeutic effect of oHSV2hGM-CSF on the B16R animal model was evaluated by recording animal survival over 110 days after tumor cells inoculation whereas all the mice in the PBS group died by day 22 (P < 0.01). The anti-tumor mechanism of the newly constructed oHSV2hGM-CSF against B16R cell tumor appeared to include the directly oncolytic activity and the induction of anti-tumor immunity to some degree.

CONCLUSIONThe findings of our study demonstrate that the newly constructed oHSV2hGM-CSF has potent anti-tumor activity in vitro to many tumor cell lines and in vive to the transplanted B16R tumor models.

Animals ; Cell Line, Tumor ; Female ; Gene Deletion ; Genetic Engineering ; Granulocyte-Macrophage Colony-Stimulating Factor ; genetics ; Herpesvirus 2, Human ; genetics ; immunology ; Humans ; Immediate-Early Proteins ; genetics ; metabolism ; Melanoma, Experimental ; pathology ; therapy ; virology ; Mice ; Mice, Inbred C57BL ; Oncolytic Virotherapy ; methods ; Oncolytic Viruses ; genetics ; physiology ; Random Allocation ; Tumor Burden ; Viral Proteins ; genetics ; metabolism ; Xenograft Model Antitumor Assays

OBJECTIVETo study the effects of intestinal microflora alteration on specific and nonspecific immune function and hematopoietic function of mice.

METHODSSixty BALB/C mice were divided at random into two groups, experimental group and control group, with 30 mice in each. The mice in the experimental group were given kanamycin 50 mg while those in the control group were given distilled water intragastrically everyday for consecutive 10 days. After the 10 day treatment all the mice were sacrificed, and the cecal contents were collected for quantitative analysis of the intestinal bacterial flora. Certain indexes of immune function, including phagocytosis rate of macrophages, number of T lymphocytes positively stained by esterase and serum interleukin 2 (IL-2) content, and the weight of the spleen, granulocyte-macrophage colony stimulating factor etc. as indexes of hematopoietic function were determined.

RESULTSIn the group, the quantity of Enterobacteriaceae, Enterococcus, Bifidobacterium and Lactobacillus were significantly lower than that in the control group (P < 0.01). The number of PFC (plaque forming cells), the phagocytosis rate of macrophage, the number of T lymphocytes with positive NANE staining, the level of IL-2 significantly decreased when compared with that in the control group (P < 0.01). The weight of the spleen in the experimental group decreased when compared with that in the control group (P < 0.01). Levels of IL-3, GM-CSF, the total number of WBC and the proportion of neutrophil remarkably decreased as compared to that in the control group (P < 0.01). Analysis of the correlations between normal microflora, immunologic and hematopoietic indexes showed that marked positive correlations between the quantity of Bifidobacteria and each immune index including the levels of IL-3 and GM-CSF. There was a positive correlation between IL-2 and IL-3, IL-2 and GM-CSF as well.

CONCLUSIONThe application of antibiotics may cause changes in the structure and quantity of intestinal microflora. The dysbacteriosis may decrease the immune function of organism. The dysbacteriosis may decrease the hemopoietic function. The dysbacteriosis, the decrease in immune and hematopoietic function may affect one another. The balance in microecosystem should be emphasized and antibiotics should be applied rationally to reduce the side effects such as dysbacteriosis.

Animals ; Anti-Bacterial Agents ; pharmacology ; Esterases ; biosynthesis ; Feces ; microbiology ; Granulocyte-Macrophage Colony-Stimulating Factor ; analysis ; Interleukin-2 ; blood ; Intestines ; drug effects ; microbiology ; Kanamycin ; pharmacology ; Macrophages ; drug effects ; physiology ; Mice ; Mice, Inbred BALB C ; Models, Animal ; Organ Size ; Phagocytosis ; drug effects ; Spleen ; drug effects ; pathology ; T-Lymphocytes ; drug effects ; metabolism

OBJECTIVETo explore the specific cytotoxic T lymphocyte (CTL) induced by dendritic cells (DC), which were transfected by the plasmid pC53-SN3 encoding p53 gene.

METHODSDC derived from HLA-A2(+) mononuclear cells of the 24-lung cancer patients was transfected with the plasmid pC53-SN3 by lipofectamine and then co-cultured with auto-unpurified T cells to induce potent CTL (T-pC53-SN3). The cytolysis of specific CTL against Calu-6, a HLA-A2(+) human lung cancer cell line, was measured by using lactate dehydrogenase (LDH) releasing assay.

RESULTSThe expression of CD(1a) and CD(83), the correlative markers of DC, increased apparently after transfected with plasmid pC53-SN3, the expression rate was (5.45 +/- 0.89)% and (3.26 +/- 0.47)% versus (52.15 +/- 11.56)% and (25.78 +/- 12.35)%. CD(14) decreased apparently, but other DC correlative markers of CD(1a), CD(40), CD(86), and HLA-DR remained almost the same as that before transfection. Compared with T-IL-2, the CTL derived from PBMNC stimulated by IL-2 (100 U/ml), the cytolytic activity of T-pC53-SN3 against Calu-6 cell line showed a significant increase, but cytolytic activity was 56.79 +/- 15.67 and 39.33 +/- 9.88, respectively, when effect cells: target cells was 10:1. The expression of the CD(8), CD(69), and CD(45)RO/CD(8) of T-pC53-SN3 cells increased significantly, but that of CD(3), CD(4), CD(86), ect, was not significantly different from those of T-pCMV-neo.

CONCLUSIONSIt showed that DC transfected by p53 gene could induce potent HLA-A(2) restrictive CTL to kill tumor cell efficiently.

Antigens, CD ; analysis ; B7-2 Antigen ; CD40 Antigens ; analysis ; Cell Line, Tumor ; immunology ; Coculture Techniques ; Cytotoxicity, Immunologic ; immunology ; Dendritic Cells ; drug effects ; immunology ; metabolism ; Granulocyte-Macrophage Colony-Stimulating Factor ; pharmacology ; Humans ; Interleukin-4 ; pharmacology ; Membrane Glycoproteins ; analysis ; T-Lymphocytes ; immunology ; Tumor Suppressor Protein p53 ; genetics ; physiology