Exploring the optimal dose of low ionizing radiation to enhance immune function: a rabbit model.

Primary liver cancer is one of the most common malignant tumors in China. Currently, immunotherapy for liver cancer is a research hotspot. Experimental studies and epidemiological investigations have confirmed the antineoplastic activity of low ionizing radiation. The aim of this study was to explore the optimal dose of low ionizing radiation to enhance immune function. Twenty-five New Zealand rabbits were randomly divided into five groups (n = 5 each): experimental group 1 (25 mGy), experimental group 2 (50 mGy), experimental group 3 (75 mGy), experimental group 4 (100 mGy), and the control group (0 mGy). VX-2 tumor tissue was injected into rabbits using a high-frequency B-ultrasound probe (3.5 MHz). Rabbits were irradiated, and on day 4 after irradiation, blood was collected from each rabbit. Blood chemistry, interleukin (IL)-4, interferon (IFN)-γ, immunoglobulin (Ig)G, and IgM levels were assessed. On day 15 after irradiation, macrophage phagocytic function was assessed. The rabbits were sacrificed, and the spleen was removed and weighed to calculate its spleen index. Each parameter was highest in the experimental group 3 (75 mGy). Thus, we suspect the optimal low ionizing radiation dose to improve immune function may be 75 mGy.

Evaluation of different b-values in DWI and 1H MRS for pancreatic cancer and pancreatitis: a rabbit model.

Pancreatic cancer is a common malignant tumor with high incidence of metastasis. Currently, there is no absolute standard for the choice of b-value for diffusion-weighted imaging (DWI) for pancreatic cancer. The b-value is rarely reported in animal model study, especially in pancreatic cancer/mass pancreatitis rabbit models. The authors' aim was to determine the different b-values to differentiate the diagnosis of pancreatic cancer and mass pancreatitis in rabbit models using DWI. When comparing the effect of different b-values in diagnostic process, the pathological results could be regarded as the gold standard. In this research, 30 healthy New Zealand rabbits were selected and divided into three groups by random number table method: group 1 (pancreatic cancer), group 2 (mass pancreatitis) and the control group (healthy). After DWI (three different b-values 333, 667, 1000 s/mm2, respectively) and MRI examination, the model rabbits were then killed. Afterward, the tumor mass was removed for biopsy, and occupation anatomy and tumor histopathology were examined. Fat-suppressing sequences of T2WI, DWI, ADC, difference of ADC (DADC), and MRS were used. The present study determined that the effective differential diagnosis of pancreatic cancer and pancreatitis was determined at low b-values (333 s/mm2) when performed DWI inspection in rabbit models.

E2F1 transactivates IQGAP3 and promotes proliferation of hepatocellular carcinoma cells through IQGAP3-mediated PKC-alpha activation.

For decades, E2F1 has been recognized as a retinoblastoma protein (RB) binding transcription factor that regulates the cell cycle. E2F1 binds preferentially to RB and accelerates the cell cycle in most cancer cells. However, it is thought that E2F1 modulates cell proliferation in other ways as well. Herein, it has been discovered that in pathological tissues derived from hepatocellular carcinoma (HCC) patients, E2F1 correlates positively with IQGAP3 and that both of these factors are highly expressed (N = 164, R = 0.6716). In addition, a high level of E2F1 or IQGAP3 predicted poor survival in HCC patients. Further study determined that E2F1 transactivates IQGAP3, the GTPase binding protein in MHCC-97H cells. Co-immunoprecipitation analysis indicated that IQGAP3 interacts with PKCδ and competitively inhibits the interaction between PKCδ and PKCα, resulting in phosphorylation of PKCα activation and promotion of cell proliferation. This study reveals that highly expressed E2F1 not only transactivates cell-cycle-related factors but also promotes HCC proliferation by activating the phosphorylation of PKCα.

Highly expressed histone deacetylase 5 promotes the growth of hepatocellular carcinoma cells by inhibiting the TAp63-maspin pathway.

Aberrant expression of histone deacetylases (HDACs) has been detected in a variety of cancers, which disrupts the balance between cell proliferation and apoptosis in favor of continuous growth. A previous study demonstrated that HDAC5 contributes to the proliferation of hepatocellular carcinoma (HCC) cells, but a clear understanding of the mechanism has not yet been provided. In the present work, we found that the levels of HDAC5 were significantly higher in HCC tissues and cells than in adjacent tissues and normal hepatic cells. In addition, knockdown of HDAC5 attenuated the proliferation of Hep3B and HepG2 cells. Through profiling the expressions of proliferation and apoptosis-related genes in Hep3B cells following HDAC5 knockdown, p63 and maspin were found obviously up-regulated in HDAC5-deprived cells compared with the control. Further investigations confirmed that HDAC5 knockdown induced TAp63 expression in HCC cells, accompanied with increased H3K9 acetylation at the TAp63 promoter. Overexpression of TAp63 led to proliferation inhibition by inducing cell cycle arrest. Additionally, TAp63 that was required for the maspin upregulation resulted from HDAC5 knockdown. Phenotype experiments showed that interrupting either TAp63 or maspin recovered the proliferative and tumorigenic capabilities of HCC cells with HDAC5 knockdown. Clinical analysis showed that HDAC5 was negatively correlated with TAp63 and maspin in HCC tissues. In addition, a high level of HDAC5 as well as a low level of TAp63 or maspin predicted poor survival in HCC patients. Taken together, this study proposes the existence of an aberrant HDAC5-TAp63-maspin pathway conferring HCC progression through proliferation induction, which suggests novel intervention targets for the disease.

Histone deacetylase 5 promotes the migration and invasion of hepatocellular carcinoma via increasing the transcription of hypoxia-inducible factor-1α under hypoxia condition.

Hypoxia plays a critical role in the progression and metastasis of hepatocellular carcinoma by activating the key transcription factor, hypoxia-inducible factor-1. This study aims to identify the novel mechanisms underlying the dysregulation of hypoxia-inducible factor-1α in hepatocellular carcinoma. We found that histone deacetylase 5, a highly expressed histone deacetylase in hepatocellular carcinoma, strengthened the migration and invasion of hepatocellular carcinoma cells under hypoxia but not normoxia condition. Furthermore, histone deacetylase 5 induced the transcription of hypoxia-inducible factor-1α by silencing homeodomain-interacting protein kinase-2 expression, which was also dependent on hypoxia. And then knockdown of hypoxia-inducible factor-1α decreased the expressions of mesenchymal markers, N-cadherin, and Vimentin, as well as matrix metalloproteinases, MMP7 and MMP9; however, the epithelial marker, E-cadherin, increased. Phenotype experiments showed that the migration and invasion of hepatocellular carcinoma cells were impaired by knockdown of histone deacetylase 5 or hypoxia-inducible factor-1α but rescued when eliminating homeodomain-interacting protein kinase-2 in hepatocellular carcinoma cells, which suggested the critical role of histone deacetylase 5-homeodomain-interacting protein kinase-2-hypoxia-inducible factor-1α pathway in hypoxia-induced metastasis. Finally, clinical analysis confirmed the positive correlation between histone deacetylase 5 and hypoxia-inducible factor-1α in hepatocellular carcinoma specimens and a relatively poor prognosis for the patients with high levels of histone deacetylase 5 and hypoxia-inducible factor-1α. Taken together, our findings demonstrated a novel mechanism underlying the crosstalk between histone deacetylase 5 and hypoxia-inducible factor-1 in hepatocellular carcinoma.

E2F1 promote the aggressiveness of human colorectal cancer by activating the ribonucleotide reductase small subunit M2.

As the ribonucleotide reductase small subunit, the high expression of ribonucleotide reductase small subunit M2 (RRM2) induces cancer and contributes to tumor growth and invasion. In several colorectal cancer (CRC) cell lines, we found that the expression levels of RRM2 were closely related to the transcription factor E2F1. Mechanistic studies were conducted to determine the molecular basis. Ectopic overexpression of E2F1 promoted RRM2 transactivation while knockdown of E2F1 reduced the levels of RRM2 mRNA and protein. To further investigate the roles of RRM2 which was activated by E2F1 in CRC, CCK-8 assay and EdU incorporation assay were performed. Overexpression of E2F1 promoted cell proliferation in CRC cells, which was blocked by RRM2 knockdown attenuation. In the migration and invasion tests, overexpression of E2F1 enhanced the migration and invasion of CRC cells which was abrogated by silencing RRM2. Besides, overexpression of RRM2 reversed the effects of E2F1 knockdown partially in CRC cells. Examination of clinical CRC specimens demonstrated that both RRM2 and E2F1 were elevated in most cancer tissues compared to the paired normal tissues. Further analysis showed that the protein expression levels of E2F1 and RRM2 were parallel with each other and positively correlated with lymph node metastasis (LNM), TNM stage and distant metastasis. Consistently, the patients with low E2F1 and RRM2 levels have a better prognosis than those with high levels. Therefore, we suggest that E2F1 can promote CRC proliferation, migration, invasion and metastasis by regulating RRM2 transactivation. Understanding the role of E2F1 in activating RRM2 transcription will help to explain the relationship between E2F1 and RRM2 in CRC and provide a novel predictive marker for diagnosis and prognosis of the disease.