OBJECTIVES: To explore the mechanism by which histone deacetylase 1 (HDAC1) regulates steroid-induced apoptosis of mouse osteocyte-like MLO-Y4 cells. METHODS: MLY-O4 cells were treated with 400 nmol/L trichostatin A (TSA) or 1 mmol/L dexamethasone for 24 h or transfected with a HDAC1-overexpressing vector prior to TSA or dexamethasone treatment. The changes in the expressions of HDAC1, SP1, cleaved caspase-3 and Bax, SP1 acetylation level, cell proliferation, and cell apoptosis were examined. The interaction between HDAC1 and SP1 was determined with immunoprecipitation assay and Western blotting. RESULTS: Treatment with dexamethasone significantly increased cell apoptosis, enhanced the expressions of cleaved caspase-3 and Bax, reduced HDAC1 expression, and suppressed proliferation of MLO-Y4 cells. Both TSA and dexamethasone obviously increased SP1 acetylation level and the expression of SP1 in MLO-Y4 cells. HDAC1 overexpression in the cells significantly attenuated the effect of TSA and dexamethasone, promoted cell proliferation, lowered the expressions of SP1, cleaved caspase-3 and Bax, and inhibited dexamethasone-induced cell apoptosis. Immunoprecipitation assay and Western blotting demonstrated the interaction between HDAC1 and SP1 in the cells. CONCLUSIONS HDAC1 inhibits dexamethasone-induced apoptosis and promotes proliferation of cultured mouse osteocytes by suppressing SP1 expression via promoting its deacetylation.
Animals ; Apoptosis/drug effects* ; Mice ; Histone Deacetylase 1/genetics* ; Osteocytes/drug effects* ; Sp1 Transcription Factor/metabolism* ; Acetylation ; Dexamethasone/pharmacology* ; Cell Proliferation/drug effects* ; Caspase 3/metabolism* ; Cell Line ; Hydroxamic Acids/pharmacology* ; bcl-2-Associated X Protein/metabolism*

Objective: To investigate the gene expression characteristics of peripheral blood mononuclear cells from patients with high altitude pulmonary hypertension (HAPH) in Naxi residents living in Lijiang, Yunnan, and to explore the underlying pathogenesis and value for potential drug selection. Methods: This is a case-control study. Six patients with HPAH (HPAH group) and 4 normal subjects (control group) were selected from the Naxi residents who originally lived in Lijiang, Yunnan Province. The general clinical data of the two groups were collected, and the related indexes of pulmonary artery pressure were collected. Peripheral blood mononuclear cells of the subjects were collected for RNA sequencing. The differences on gene expression, regulatory network of transcription factors and drug similarity between the two groups were compared. The results were compared with the public data of idiopathic pulmonary arterial hypertension (IPAH). Biological processes and signal pathways were analyzed and compared between HPAH and IPAH patients. Results: The age of 6 patients with HAPH was (68.1±8.3) years old, and there were 2 males (2/6). The age of 4 subjects in the control group was (62.3±10.9) years old, and there were 2 males (2/4). Tricuspid regurgitation velocity, tricuspid pressure gradient and pulmonary systolic pressure in HAPH group were significantly higher than those in control group (all P<0.05). The results of RNA sequencing showed that compared with the control group, 174 genes were significantly upregulated and 169 genes were downregulated in peripheral blood mononuclear cells of HAPH group. These differentially expressed genes were associated with 220 biological processes, 52 molecular functions and 23 cell components. A total of 21 biological processes and 2 signal pathways differed between HPAH and IPAH groups, most of which were related to inflammation and immune response. ZNF384, SP1 and STAT3 were selected as highly correlated transcription factors by transcription factor prediction analysis. Trichostatin A and vorinostat were screened out as potential drugs for the treatment of HAPH by drug similarity analysis. Conclusions: There are significant differences in gene expression in peripheral blood monocytes between HAPH patients and normal population, and inflammation and immune dysfunction are the main pathogenic factors. Trichostatin A and Vorinostat are potential drugs for the treatment of HAPH.
Aged ; Altitude ; Altitude Sickness/genetics* ; Case-Control Studies ; China ; Familial Primary Pulmonary Hypertension/genetics* ; Humans ; Hydroxamic Acids/therapeutic use* ; Hypertension, Pulmonary/genetics* ; Inflammation ; Leukocytes, Mononuclear/pathology* ; Male ; Middle Aged ; Transcription Factors ; Transcriptome/genetics* ; Vorinostat/therapeutic use*

Objective: To investigate the effects of deferoxamine on macrophage polarization and wound healing in mice with deep tissue injury (DTI) and its mechanism. Methods: The experimental research methods were adopted. Fifty-four male C57BL/6J mice of 6-8 weeks old were divided into DTI control group, 2 mg/mL deferoxamine group, and 20 mg/mL deferoxamine group according to random number table, with 18 mice in each group. DTI was established on the back of mice by magnet compression method. From post injury day (PID) 1, mice were injected subcutaneously with 100 µL normal saline or the corresponding mass concentration of deferoxamine solution every other day at the wound edge until the samples were collected. Another 6 mice without any treatment were selected as normal control group. Six mice in each of the three DTI groups were collected on PID 3, 7, and 14 to observe the wound changes and calculate the wound healing rate. Normal skin tissue of mice in normal control group was collected on PID 3 in other groups (the same below) and wound tissue of mice in the other three groups on PID 7 and 14 was collected for hematoxylin-eosin (HE) staining to observe the tissue morphology. Normal skin tissue of mice in normal control group and wound tissue of mice in the other three groups on PID 7 were collected, and the percentages of CD206 and CD11c positive area were observed and measured by immunohistochemical staining, and the mRNA and protein expressions of CD206, CD11c, and inducible nitric oxide synthase (iNOS) were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction and Western blotting, respectively. Normal skin tissue of mice in normal control group and wound tissue of mice in DTI control group and 20 mg/mL deferoxamine group were collected on PID 3, 7, and 14, and the protein expressions of signal transducer and activator of transcription 3 (STAT3) and interleukin-10 (IL-10) were detected by Western blotting. The sample number in each group at each time point in the above experiments. The RAW264.7 cells were divided into 50 μmol/L deferoxamine group, 100 μmol/L deferoxamine group, 200 μmol/L deferoxamine group, and blank control group, which were treated correspondingly, with 3 wells in each group. The positive cell percentages of CD206 and CD86 after 48 h of culture were detected by flow cytometry. Data were statistically analyzed with analysis of variance for repeated measurement, one-way analysis of variance, and least significant difference test. Results: On PID 7, the wound healing rates of mice in 2 mg/mL and 20 mg/mL deferoamine groups were (17.7±3.7)% and (21.5±5.0)%, respectively, which were significantly higher than (5.1±2.3)% in DTI control group (P<0.01). On PID 14, the wound healing rates of mice in 2 mg/mL and 20 mg/mL deferoamine groups were (51.1±3.8)% and (57.4±4.4)%, respectively, which were significantly higher than (25.2±3.8)% in DTI control group (P<0.01). HE staining showed that the normal skin tissue layer of mice in normal control group was clear, the epidermis thickness was uniform, and skin appendages such as hair follicles and sweat glands were visible in the dermis. On PID 7, inflammation in wound tissue was obvious, the epidermis was incomplete, and blood vessels and skin appendages were rare in mice in DTI control group; inflammatory cells in wound tissue were reduced in mice in 2 mg/mL and 20 mg/mL deferoxamine groups, and a few of blood vessels and skin appendages could be seen. On PID 14, inflammation was significantly alleviated and blood vessels and skin appendages were increased in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoxamine groups compared with those in DTI control group. On PID 7, the percentages of CD206 positive area in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoxamine groups were significantly higher than that in DTI control group (P<0.01), the percentage of CD206 positive area in wound tissue of mice in DTI control group was significantly lower than that in normal skin tissue of mice in normal control group (P<0.01), the percentage of CD206 positive area in wound tissue of mice in 20 mg/mL deferoxamine group was significantly higher than that in normal skin tissue of mice in normal control group (P<0.01). The percentages of CD11c positive area in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoxamine groups were significantly lower than those in DTI control group and normal skin tissue in normal control group (P<0.05 or P<0.01), and the percentage of CD11c positive area in normal skin tissue of mice in normal control group was significantly higher than that in DTI control group (P<0.05). On PID 7, the CD206 mRNA expressions in the wound tissue of mice in 2 mg/mL and 20 mg/mL deferoxamine groups were significantly higher than that in DTI control group (P<0.01), but significantly lower than that in normal skin tissue in normal control group (P<0.01); the CD206 mRNA expression in wound tissue of mice in DTI control group was significantly lower than that in normal skin tissue in normal control group (P<0.01). The mRNA expressions of CD11c and iNOS in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoamine groups were significantly lower than those in DTI control group (P<0.01). The mRNA expressions of CD11c in the wound tissue of mice in DTI control group, 2 mg/mL and 20 mg/mL deferoamine groups were significantly higher than that in normal skin tissue in normal control group (P<0.01). Compared with that in normal skin tissue in normal control group, the mRNA expressions of iNOS in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoamine groups were significantly decreased (P<0.01), and the mRNA expression of iNOS in wound tissue of mice in DTI control group was significantly increased (P<0.01). On PID 7, the protein expressions of CD206 in the wound tissue of mice in 2 mg/mL and 20 mg/mL deferoamine groups were significantly higher than those in DTI control group and normal skin tissue in normal control group (P<0.01), and the protein expression of CD206 in wound tissue of mice in DTI control group was significantly lower than that in normal skin tissue in normal control group (P<0.01). The protein expressions of CD11c and iNOS in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoamine groups were significantly lower than those in DTI control group (P<0.01). The protein expressions of CD11c and iNOS in wound tissue of mice in DTI control group were significantly higher than those in normal skin tissue in normal control group (P<0.01). The CD11c protein expressions in wound tissue of mice in 2 mg/mL and 20 mg/mL deferoamine groups were significantly higher than those in normal skin tissue in normal control group (P<0.05 or P<0.01). The protein expression of iNOS in wound tissue of mice in 2 mg/mL deferoamine group was significantly lower than that in 20 mg/mL deferoamine group and normal skin tissue in normal control group (P<0.05). On PID 3, 7, and 14, the protein expressions of STAT3 and IL-10 in wound tissue of mice in 20 mg/mL deferoxamine group were significantly higher than those in DTI control group (P<0.05 or P<0.01), and the protein expressions of STAT3 were significantly higher than those in normal skin tissue in normal control group (P<0.05 or P<0.01). On PID 7 and 14, the protein expressions of IL-10 in wound tissue of mice in 20 mg/mL deferoxamine group were significantly higher than those in normal skin tissue in normal control group (P<0.01). On PID 3, 7, and 14, the protein expressions of IL-10 in wound tissue of mice in DTI control group were significantly lower than those in normal skin tissue in normal control group (P<0.05 or P<0.01). After 48 h of culture, compared with those in blank control group, the CD206 positive cell percentages in 100 μmol/L and 200 μmol/L deferoamine groups were significantly increased (P<0.01), while the CD86 positive cell percentages in 100 μmol/L and 200 μmol/L deferoamine groups were significantly decreased (P<0.01). Conclusions: Deferoxamine can promote the polarization of macrophages toward the anti-inflammatory M2 phenotype and improve wound healing by enhancing the STAT3/IL-10 signaling pathway in DTI mice.
Animals ; Deferoxamine/pharmacology* ; Inflammation ; Interleukin-10 ; Macrophages ; Male ; Mice ; Mice, Inbred C57BL ; Wound Healing

OBJECTIVE: To investigate the effect of local administration of deferoxamine mesylate (DFO) on vascularization and osteogenesis and its ability to maintain the activity of hypoxia inducible factor-1α (HIF-1α), by constantly observing early changes of vessel-like structures and bone tissues during bone defects healing. METHODS: Skull critical bone defect models were constructed on a total of thirty male SD rats (6-8 weeks old). The rats were randomly divided into experimental group (DFO group) or control group (normal saline group). 300 μL 200 μmol/L DFO solution or normal saline was locally injected on the 4th day after the defect was made. On the 5th, 7th, 10th, 14th, and 28th days after surgery, three rats in each group were sacrificed respectively. HE staining and Masson staining were performed to observe new bone formation and mineralization. HIF-1α immunohistochemistry staining was performed to examine relative expression of protein. Qualitative analysis and comparation were performed by t-tests on relative expression of HIF-1α, numbers of blood vessels and percentages of mineralization tissues of new bone areas. RESULTS: On the 5th, 7th, 10th, 14th and 28th days after surgery, the average numbers of blood vessels were 30.40±12.15, 62.00±17.87, 73.43±15.63, 40.00±7.84, 48.71±11.64 in the DFO group, and 18.75±6.63, 19.13±2.80, 51.35±16.21, 27.18±7.32, 30.88±13.43 in the control group. The number of blood vessels in the DFO group was significantly higher than that of the control group at each time point (P < 0.05). The mass of new bone in the DFO group was higher than that in the control group on the 14th and 28th days after surgery. The percentage of mineralization tissues of new bone area on the 14th and 28th days after injection were (27.73±5.93)% and (46.53±3.66)% in the DFO group, and (11.99±2.02)% and (31.98±4.22)% in the control group. The percentage of mineralization tissues in the DFO group was significantly higher than that of the control group at each time point (P < 0.001). The relative expression of HIF-1α in the DFO group compared with the control group was 2.86±0.48, 1.32±0.26, 1.32±0.32, 1.28±0.38 and 1.05±0.34 on the 5th, 7th, 10th, 14th and 28th days, with significant expression difference on the 5th day (P < 0.01). CONCLUSION Use of DFO in bone defects promotes vascularization and osteogenesis in the defect area, and maintains the protein activity of HIF-1α temporarily.
Animals ; Bone Regeneration ; Deferoxamine/therapeutic use* ; Male ; Rats ; Rats, Sprague-Dawley ; Skull

OBJECTIVE: To explore the analgesic mechanism of intrathecal trichostatin A (TSA) injection in a rat model of neuropathic pain induced by chronic constrictive injury (CCI). METHODS: Male SD rats were randomized into sham operation+ DMSO group (group S), CCI +DMSO group (group C), CCI +10 μg TSA group (group T), and in the latter two groups, rat models of neuropathic pain were established induced by CCI. The rats were given intrathecal injections of 10 μL 5% DMSO or 10 μg TSA (in 5% DMSO) once a day on days 7 to 9 after CCI or sham operation. The rats were euthanized after behavioral tests on day 10, and the lumbar segment of the spinal cord was sampled to determine the expression of histone deacetylase 4 (HDAC4) protein and mRNA and detect the differentially expressed miRNAs using a miRNA chip. MiR-190b-5p and miR-142-3p were selected for validation of the results using RT-qPCR. RESULTS: Compared with those in group S, the rats in group C showed significantly decreased paw withdrawal mechanical threshold (PWMT) from day 3 to day 10 after CCI ( < 0.05); intrathecal injection of TSA significantly reversed the reduction of PWMT following CCI ( < 0.05). Positive HDAC4 expression was detected mainly in the cytoplasm of the neurons in the gray matter of the spinal cord, and was obviously up-regulated after CCI ( < 0.05). Intrathecal injection of TSA significantly suppressed CCI-induced up-regulation of HDAC4 at 10 days after the operation ( < 0.05). Compared with the miRNA profile in group S, miRNA profiling identified 83 differentially expressed miRNAs in group C (fold change ≥2 or ≤0.5, < 0.05); TSA treatment reversed the expressions of 58 of the differentially expressed miRNAs following CCI, including 41 miRNAs that were decreased after CCI but up-regulated following TSA treatment. The results of real-time PCR validated the changes in the expressions of miR-190b-5p and miR-142-3p. CONCLUSIONS TSA suppresses CCI-induced up-regulation of HDAC4 and reverses differential expressions of miRNAs in the spinal cord of rats, which may contribute to the analgesic effect of TSA on neuropathic pain.
Animals ; Histone Deacetylases ; Hydroxamic Acids ; Male ; MicroRNAs ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; Up-Regulation

There is still a need for better protection against or mitigation of the effects of ionizing radiation following conventional radiotherapy or accidental exposure. The objective of our current study was to investigate the possible roles of matrix metalloproteinase inhibitor, ilomastat, in the protection of mice from total body radiation (TBI), and the underlying protective mechanisms. Ilomastat treatment increased the survival of mice after TBI. Ilomastat pretreatment promoted recovery of hematological and immunological cells in mice after 6 Gy γ-ray TBI. Our findings suggest the potential of ilomastat to protect against or mitigate the effects of radiation.
Acute Radiation Syndrome ; blood ; immunology ; prevention & control ; Animals ; Blood Cells ; drug effects ; radiation effects ; Dose-Response Relationship, Drug ; Gamma Rays ; adverse effects ; Hydroxamic Acids ; therapeutic use ; Indoles ; therapeutic use ; Matrix Metalloproteinase Inhibitors ; therapeutic use ; Mice ; Radiation Injuries, Experimental ; blood ; immunology ; prevention & control ; Radiation-Protective Agents ; therapeutic use ; Spleen ; drug effects ; immunology ; radiation effects ; Survival Analysis ; Whole-Body Irradiation

OBJECTIVETo explore the anti-myeloma effect of suberoylanilide hydroxamic acid (SAHA) and on mouse myeloma cell line SP2/0 in vitro and in vivo and its mechanism.

METHODSThe inhibitory effect of SAHA on SP2/0 cells was measured by CCK-8 assay,and the apoptosis and cell cycle were analyzed by flow cytometry FACS. The protein expression of Caspase-3 and p53 of SP2/0 cells treated with SAHA were examined by Western blot. Annexin V/7-AAD double staining was performed to detect the apoptosis of SP2/0 induced by SAHA in vitro. SP2/0 cells (1×10) resuspended in 200 µl PBS were inoculated subcutaneously and intravenously into BALB/c mice, so as to establish aggressive or non-aggressive myeloma-bearing mouse models respectively. On day 3 after modeling, mice received SAHA or vehicle control treatment by intraperitoneal injection. The dose of SAHA was 60 mg/kg·d, 5 times a week for 3 weeks.

RESULTSIn SAHA-treated SP2/0 cells, the proliferation inhibition rate and apoptotic cells increased in a dose dependent manner. Also, SAHA significantly increased the ratio of cells in G phase and decreased in S phase. Molecular mechanisms of apoptosis and cell cycle arrest of SP2/0 induced by SAHA partly correlated with up-regulating the expression level of Caspase-3 and p53. In the non-aggressive myeloma-bearing mice, SP2/0 cells disappeared in peripheral blood after SAHA treatment. In the aggressive myeloma-bearing mice, inhibition of tumor growth and prolongation of the cell survival were observed after SAHA treatment.

CONCLUSIONSAHA inhibited SP2/0 cell proliferation, this effect associates with inducing apoptosis and cell cycle arrest, the mechanism of SAHA ralates partly with activating Caspase-3 and p53 pathway.

Animals ; Antineoplastic Agents ; Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; Histone Deacetylase Inhibitors ; Hydroxamic Acids ; Mice ; Mice, Inbred BALB C ; Multiple Myeloma

Objective: To explore effects of histone deacetylase inhibitor Belinostat on the immunologic function of dendritic cells (DC) and its possible mechanism. Methods: Cultured mouse bone marrow-derived DC from C57BL/6 mouse in vitro. The experiments were divided into 0, 50, 100 nmol/L Belinostat + immature DC (imDC) group, and 0, 50, 100 nmol/L Belinostat mature DC (mDC). The changes of the ultrastructure of DC were observed by transmission electron microscope (TEM). Immunophenotype and CCR7 expression rate were detected by FCM, and the migration rate was observed by chemotaxis assay. The proliferation of lymphocytes stimulated by different DC was detected by mixed lymphocyte culture reaction. The cytokines in the culture supernatant, including TNF-α, IL-12 and IL-10, were examined by ELISA. RQ-PCR was used to examine the relative expression of mRNA in RelB. Results: Successful cultured and identified the qualified imDC and mDC. Belinostat decreased the expression of CCR7 on imDC [(25.82±7.25)% vs (50.44±5.61)% and (18.71±2.00)% vs (50.44±5.61)%], meanwhile increased the rate on mDC [(71.14±1.96)% vs (64.90±1.47)%]. Chemotaxis assay showed that the migration rate of Belinostat+imDC and Belinostat+mDC group were both decreased, but the difference in imDC was not significant. T lymphocyte proliferation rate stimulated by 100 nmol/L Belinostat+imDC group was lower than imDC group in condition irritation cell∶reaction cell=1∶2 [(227.09±13.49)% vs (309.49±53.69)%]. Belinostat significantly suppressed the secretion of cytokines TNF-α, IL-12 and IL-10 (all P<0.01). The relative expression of mRNA in RelB was slightly decreased in Belinostat+imDC and Belinostat+mDC group (all P<0.05). Conclusion: Belinostat could effectly suppress DC maturation and regulate immune tolerance of DC, which may be due to the down-regulation of mRNA level of RelB in DC.
Animals ; Cells, Cultured ; Dendritic Cells ; Histone Deacetylase Inhibitors ; Hydroxamic Acids ; Mice ; Mice, Inbred C57BL ; Sulfonamides

BACKGROUNDPlacental multidrug resistance-associated protein 2 (MRP2), encoded by ABCC2 gene in human, plays a significant role in regulating drugs' transplacental transfer rates. Studies on placental MRP2 regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the roles of epigenetic mechanisms in regulating placental drug transporters are still unclear. This study aimed to investigate the effect of histone deacetylases (HDACs) inhibition on MRP2 expression in the placental trophoblast cell line and to explore whether HDAC1/2/3 are preliminarily involved in this process.

METHODSThe human choriocarcinoma-derived trophoblast cell line (Bewo cells) was treated with the HDAC inhibitors-trichostatin A (TSA) at different concentration gradients of 0.5, 1.0, 3.0, and 5.0 μmol/L. Cells were harvested after 24 and 48 h treatment. Small interfering RNA (siRNA) specific for HDAC1/HDAC2/HDAC3 or control siRNA was transfected into cells. Total HDAC activity was detected by colorimetric assay kits. HDAC1/2/3/ABCC2 messenger RNA (mRNA) and protein expressions were determined by real-time quantitative polymerase chain reaction and Western-blot analysis, respectively. Immunofluorescence for MRP2 protein expression was visualized and assessed using an immunofluorescence microscopy and ImageJ software, respectively.

RESULTSTSA could inhibit total HDAC activity and HDAC1/2/3 expression in company with increase of MRP2 expression in Bewo cells. Reduction of HDAC1 protein level was noted after 24 h of TSA incubation at 1.0, 3.0, and 5.0 μmol/L (vs. vehicle group, all P < 0.001), accompanied with dose-dependent induction of MRP2 expression (P = 0.045 for 1.0 μmol/L, P = 0.001 for 3.0 μmol/L, and P < 0.001 for 5.0 μmol/L), whereas no significant differences in MRP2 expression were noted after HDAC2/3 silencing. Fluorescent micrograph images of MRP2 protein were expressed on the cell membrane. The fluorescent intensities of MRP2 in the control, HDAC2, and HDAC3 siRNA-transfected cells were week, and no significant differences were noticed among these three groups (all P > 0.05). However, MRP2 expression was remarkably elevated in HDAC1 siRNA-transfected cells, which displayed an almost 3.19-fold changes in comparison with the control siRNA-transfected cells (P < 0.001).

CONCLUSIONSHDACs inhibition could up-regulate placental MRP2 expression in vitro, and HDAC1 was probably to be involved in this process.

Cell Line ; Histone Deacetylase 1 ; metabolism ; Histone Deacetylase 2 ; metabolism ; Histone Deacetylase Inhibitors ; pharmacology ; Histone Deacetylases ; metabolism ; Humans ; Hydroxamic Acids ; pharmacology ; Microscopy, Fluorescence ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; RNA, Messenger ; Trophoblasts ; cytology ; metabolism

PURPOSE: When integrating molecularly targeted compounds in radiotherapy, synergistic effects of the systemic agent and radiation may extend the limits of patient tolerance, increasing the demand for understanding the pathophysiological mechanisms of treatment toxicity. In this Pelvic Radiation and Vorinostat (PRAVO) study, we investigated mechanisms of adverse effects in response to the histone deacetylase (HDAC) inhibitor vorinostat (suberoylanilide hydroxamic acid, SAHA) when administered as a potential radiosensitiser. MATERIALS AND METHODS: This phase I study for advanced gastrointestinal carcinoma was conducted in sequential patient cohorts exposed to escalating doses of vorinostat combined with standard-fractionated palliative radiotherapy to pelvic target volumes. Gene expression microarray analysis of the study patient peripheral blood mononuclear cells (PBMC) was followed by functional validation in cultured cell lines and mice treated with SAHA. RESULTS: PBMC transcriptional responses to vorinostat, including induction of apoptosis, were confined to the patient cohort reporting dose-limiting intestinal toxicities. At relevant SAHA concentrations, apoptotic features (annexin V staining and caspase 3/7 activation, but not poly-(ADP-ribose)-polymerase cleavage) were observed in cultured intestinal epithelial cells. Moreover, SAHA-treated mice displayed significant weight loss. CONCLUSION: The PRAVO study design implemented a strategy to explore treatment toxicity caused by an HDAC inhibitor when combined with radiotherapy and enabled the identification of apoptosis as a potential mechanism responsible for the dose-limiting effects of vorinostat. To the best of our knowledge, this is the first report deciphering mechanisms of normal tissue adverse effects in response to an HDAC inhibitor within a combined-modality treatment regimen.
Animals ; Apoptosis* ; Cells, Cultured ; Clinical Trials, Phase I as Topic ; Cohort Studies ; Drug-Related Side Effects and Adverse Reactions ; Epithelial Cells ; Gene Expression ; Histone Deacetylase Inhibitors* ; Histone Deacetylases* ; Histones* ; Humans ; Hydroxamic Acids ; Mice ; Microarray Analysis ; Radiotherapy* ; Weight Loss