13-Cis Retinoic Acid Induces Neuronal Differentiation in Daoy (Medulloblastoma) Cells Through Epigenetic Regulation of Topoisomerase IIß.

Medulloblastoma (MB) is a malignant tumor of the cerebellum that occurs in children and infants. Abnormal neuronal differentiation can lead to brain tumors, and topoisomerase IIß (Top IIß) plays an important role in neuronal differentiation. The aim of this study was to investigate the molecular mechanism of 13-cis retinoic acid (13-cis RA) promoting the expression of Top IIß and inducing neuronal differentiation in human MB Daoy cells. The results showed that 13-cis RA inhibited the cell proliferation and induced cell cycle arrest in G0/G1 phase. The cells differentiated into a neuronal phenotype, with high expression of the neuronal marker microtubule-associated protein 2 (MAP2) and abundant Top IIß, and obvious neurite growth. Chromatin immunoprecipitation (ChIP) assay showed that histone H3 lysine 27 tri-methylation (H3K27me3) modification in Top IIß promoter decreased after 13-cis RA-induced cell differentiation, while jumonji domain-containing protein 3 (JMJD3) binding in Top IIß promoter increased. These results suggest that H3K27me3 and JMJD3 can regulate the expression of Top IIß gene, which is related to inducing neural differentiation. Our results provide new insights into understanding the regulatory mechanisms of Top IIß during neuronal differentiation and imply the potential application of 13-cis RA in the clinical treatment of MB.

Prevalence and Impact Factors of COVID-19 Vaccination Hesitancy Among Breast Cancer Survivors: A Multicenter Cross-Sectional Study in China.

Cancer patients are at a high risk of being infected with COVID-19 and have a poor prognosis after infection. Breast cancer is one of the most common cancers. Since vaccination is an effective measure to prevent the spread of COVID-19, we studied the vaccination rate among breast cancer survivors and analyzed their characteristics to provide evidence for boosting the vaccination rate. The researchers conducted a multicenter, cross-sectional study on 747 breast cancer survivors from six hospitals in Wuhan city between June 5, 2021, and June 12, 2021. The self-administrated questionnaires based on relevant studies were distributed. The researchers then compared differences in characteristics among vaccinated patients, hesitant patients, and non-vaccinated patients. Moreover, they performed univariable and multivariable logistic regression analyses to identify potential factors associated with vaccination hesitancy. The researchers assessed a total of 744 breast cancer survivors -94 cases in the vaccinated group, 103 in the planning group, 295 in the hesitancy group, and 252 in the refusal group. The vaccination rate was 12.63% (95% CI 10.25-15.02%) and 37.23% (95% CI 27.48-47.82%) patients reported adverse reactions. The vaccination hesitancy/refusal rate was 73.52% (95% CI 70.19-76.66%), which was independently associated with current endocrine or targeted therapy (odds ratio [OR] = 1.52, 95% CI 1.03-2.24), no notification from communities or units (OR = 2.46, 95% CI 1.69-3.59) and self-perceived feel (general vs. good, OR = 1.46, 95% CI 1.01-2.13; bad vs. good, OR = 4.75, 95% CI 1.85-12.16). In the hesitancy/refusal group, the primary reason was "I did not know who to ask whether I can get vaccinated" (46.07%), the person who would most influence decisions of patients was the doctor in charge of treatment (35.83%). Effective interaction between doctors and patients, simple and consistent practical guidelines on vaccination, and timely and positive information from authoritative media could combat misinformation and greatly reduce vaccine hesitancy among breast cancer survivors.

[Effect of IL-24 gene expression on the growth of glioma cells in vitro and in vivo].

OBJECTIVE: To investigate the effect of IL-24 expression on the growth of glioma cells. METHODS: The IL-24 gene was transfected into rat glioma C6 cells with a retroviral vector. The expression of IL-24 in C6/IL-24 glioma cells was confirmed by RT-PCR. MTT assay and flow cytometry were used to study tumor cell proliferation in vitro. Tumorigenicity in vivo was studied in inbred SD male rats by the growth of intracerebrally inoculated tumor. RESULTS: It was confirmed by RT-PCR that the exogenous IL-24 gene expressed in C6/IL-24 cell. The C6/IL-24 cell proliferation in vitro and tumorigenicity in vivo were both inhibited compared with its parental C6 cell. CONCLUSION: IL-24 expression in glioma cells somehow inhibits their growth in vitro and in vivo.

Tetramethylpyrazine induces SH-SY5Y cell differentiation toward the neuronal phenotype through activation of the PI3K/Akt/Sp1/TopoIIß pathway.

Tetramethylpyrazine (TMP) is an active compound extracted from the traditional Chinese medicinal herb Chuanxiong. Previously, we have shown that TMP induces human SH-SY5Y neuroblastoma cell differentiation toward the neuronal phenotype by targeting topoisomeraseIIß (TopoIIß), a protein implicated in neural development. In the present study, we aimed to elucidate whether the transcriptional factors specificity protein 1 (Sp1) and nuclear factor Y (NF-Y), in addition to the upstream signaling pathways ERK1/2 and PI3K/Akt, are involved in modulating TopoIIß expression in the neuronal differentiation process. We demonstrated that SH-SY5Y cells treated with TMP (80µM) terminally differentiated into neurons, characterized by increased neuronal markers, tubulin ßIII and microtubule associated protein 2 (MAP2), and increased neurite outgrowth, with no negative effect on cell survival. TMP also increased the expression of TopoIIß, which was accompanied by increased expression of Sp1 in the differentiated neuron-like cells, whereas NF-Y protein levels remained unchanged following the differentiation progression. We also found that the phosphorylation level of Akt, but not ERK1/2, was significantly increased as a result of TMP stimulation. Furthermore, as established by chromatin immunoprecipitation (ChIP) assay, activation of the PI3K/Akt pathway increased Sp1 binding to the promoter of the TopoIIß gene. Blockage of PI3K/Akt was shown to lead to subsequent inhibition of TopoIIß expression and neuronal differentiation. Collectively, the results indicate that the PI3K/Akt/Sp1/TopoIIß signaling pathway is necessary for TMP-induced neuronal differentiation. Our findings offer mechanistic insights into understanding the upstream regulation of TopoIIß in neuronal differentiation, and suggest potential applications of TMP both in neuroscience research and clinical practice to treat relevant diseases of the nervous system.

Mechanism of multidrug resistance of human small cell lung cancer cell line H446/VP.

BACKGROUND: Small cell lung cancer (SCLC) is the most aggressive form of lung cancer. This study aimed to investigate the mechanism of human small cell lung cancer cell line resistance to etoposide (VP-16), H446/VP. METHODS: The cell viability was measured by MTT assay. Immunocytochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting methods were used to detect the multidrug resistance gene (MDR1), bcl-2, bax and the topoisomerase II (Topo II) expressions in H446 and H446/VP cells after treated with or without VP-16. RESULTS: The 50% inhibition concentration (IC50) of VP-16 on H446 cells was 49 mg/L, and 836 mg/L was for H446/VP cells. The expressions of MDR1 and bcl-2 were up-regulated, while the amounts of bax and Topo II were reduced in H446/VP cells. After treated with 49 mg/L of VP-16, it showed that the drug could significantly inhibit bcl-2 and Topo II expressions, and increase bax expression in H446 cells compared with that of H446/VP cells. CONCLUSIONS: The H446/VP cell was stably resistant to VP-16. The decreased expression of Topo II was correlated with the H446/VP multidrug resistance. The elevated expressions of MDR1, and the altered apoptotic pathways also played an important role in VP-16 induced multidrug resistance of SCLC.

[Synergetic cytotoxicity of cisplatin and etoposide to leukemia cell line K562 and its mechanism].

BACKGROUND & OBJECTIVE: Etoposide (VP-16) is one of the most common chemotherapy drugs, but its usage is limited by drug resistance. Some researches on solid tumors show that cisplatin (DDP) have synergetic effect with VP-16. This study was to evaluate synergetic cytotoxicity of VP-16 and DDP to leukemia cell line K562, and explore the mechanism. METHODS: K562 cells were treated with VP-16 (0 or 5 microg/ml) and DDP (0, 0.3, 3, 15, or 30 microg/ml) in different combination patterns. Inhibitory effect of VP-16 and DDP on survival of K562 cells was measured by MTT assay. Cell apoptosis was evaluated by AO/EB double fluorescent labeling. The expression of topoisomerase (TOPO) II alpha and II beta, and transcription factor Sp1 and Sp3 were measured by semi-quantitive reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. RESULTS: MTT assay showed significant synergetic cytotoxicity of VP-16 and DDP. VP-16 in combination with DDP obviously enhanced cell apoptosis. RT-PCR showed that DDP significantly up-regulated the expression of TOPO II and Sp1 in concentration-dependent manners (TOPO II alpha, II beta, and Sp1 were up-regulated by 36%, 25%, and 75% of control, respectively, when treated with 30 microg/ml of DDP), and down-regulated Sp3 by 49% of control; VP-16 (5 microg/ml) down-regulated TOPO II alpha by 71.9%, and up-regulated Sp3 by 14%; VP-16 (5 microg/ml) in combination with DDP (30 microg/ml) up-regulated TOPO II alpha by 83%, II beta by 11%, and Sp1 by 58% when compared with using VP-16 alone (but the levels were lower than using DDP alone), and down-regulated Sp3 by 61.3% when compared with using DDP alone. Western blot showed similar results to RT-PCR. CONCLUSION: Through up-regulating TOPO II, DDP could enhance the chemotherapeutic effect of VP-16 on K562 cells by provide more target enzyme to act on.

Expressions of cyclin B1 and p21cipl in adult acute leukemia and their correlation.

Cyclin B1, a positive regulator, controls mitosis occurrence, plays an important role in cell proliferation. To investigate the clinical significance of cyclin B1, the expression of cyclin B1 in acute leukemia (AL) patients was measured; the expression of cyclin B1 and p21(cipl), and their cell cycle distribution were assayed by flow cytometry in 136 adult patients with newly diagnosed AL, 10 continuous complete remission (CCR) AL and 17 normal controls; the mRNA of cyclin B1 and p21(cipl), and the proliferation cell nuclear antigen (PCNA) in patients and normal controls were detected with semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The results showed that the expression of cyclin B1 in newly diagnosed AL patients was significantly higher than that in normal controls. For the relapsed AL patients, the cyclin B1 expression was also higher than that in normal controls, but lower than that in newly diagnosed cases, there was no significant difference between the remission cases and normal controls, nor difference between CCR AL patients and normal controls. All patients with high cyclin B1 expression had an unscheduled expression manner, that cyclin B1 protein appeared in G(1) phase, and in some case it even higher than that of G(2) phase. The response rate (partial remission + complete remission) and survival rate in the cyclin B1 high expressed patients were higher than that of cyclin B1 low expressed patients. The relapse rate in cyclin B1 high expressed patients was higher than that in cyclin B1 normally expressed patients. The survival rate in cyclin B1 high expressed patients was higher than that in cyclin B1 low expression patients. A negative correlation between the expression of cyclin B1 and p21(cipl) was observed. Additionally, cyclin B1 protein expression was generally correlated with proliferation index (PI) and proliferation cell nuclear antigen (PCNA). It is concluded that this study demonstrates for the first time cyclin B1 overexpression and abnormally distribution in cell cyclin of newly diagnosed AL patients. It was considered that cyclin B1 may play an important role in leukemic pathogeneses and can be one of the factors influencing the prognosis of AL patients.

[Retrovirus-mediated IL-18 gene expression in rat C6 glioma cell line].

AIM: To set up rat C6 glioma cell line C6/IL-18 expressing IL-18 gene and explore the effect of IL-18 on the growth of C6 cells. METHODS: The IL-18 gene was transferred into the C6 cells by a retrovirus vector. After screening with G418, the C6/IL-18 cells were obtained. IL-18 mRNA expression in C6/IL-18 cells was detected with RT-PCR. The expression of IL-18 protein was detected by flow cytometry and immunocytochemical staining. In order to analyze the activity of the expressed IL-18 protein, ELISA was used to detect the ability to secrete IFN-gamma by rat splenocytes induced with the culture supernatant of C6/IL-18 cells. The in-vitro proliferation of C6/IL-18 cells was detected by MTT colorimetry and flow cytometry. The rat model was used to observe the tumorigenic activity of the C6/IL-18 cells. RESULTS: IL-18 mRNA and protein were stably expressed in C6/IL-18 cells. The culture supernatant of C6/IL-18 cells induced secretion of IFN-gamma by rat splenocytes. At the same time, the proliferation rate and in-vivo tumorigenicity of C6/IL-18 cells were markedly reduced as compared with parental C6 cells. CONCLUSION: Exogenous IL-18 gene can inhibit the proliferation and in-vivo tumorigenicity of C6 cells.