A comparison of the biological effects of 125I seeds continuous low-dose-rate radiation and 60Co high-dose-rate gamma radiation on non-small cell lung cancer cells.

To compare the biological effects of 125I seeds continuous low-dose-rate (CLDR) radiation and 60Co γ-ray high-dose-rate (HDR) radiation on non-small cell lung cancer (NSCLC) cells.A549, H1299 and BEAS-2B cells were exposed to 125I seeds CLDR radiation or 60Co γ-ray HDR radiation. The survival fraction was determined using a colony-forming assay. The cell cycle progression and apoptosis were detected by flow cytometry (FCM). The expression of the apoptosis-related proteins caspase-3, cleaved-caspase-3, PARP, cleaved-PARP, BAX and Bcl-2 were detected by western blot assay.After irradiation with 125I seeds CLDR radiation, there was a lower survival fraction, more pronounced cell cycle arrest (G1 arrest and G2/M arrest in A549 and H1299 cells, respectively) and a higher apoptotic ratio for A549 and H1299 cells than after 60Co γ-ray HDR radiation. Moreover, western blot assays revealed that 125I seeds CLDR radiation remarkably up-regulated the expression of Bax, cleaved-caspase-3 and cleaved-PARP proteins and down-regulated the expression of Bcl-2 proteins in A549 and H1299 cells compared with 60Co γ-ray HDR radiation. However, there was little change in the apoptotic ratio and expression of apoptosis-related proteins in normal BEAS-2B cells receiving the same treatment.125I seeds CLDR radiation led to remarkable growth inhibition of A549 and H1299 cells compared with 60Co HDR γ-ray radiation; A549 cells were the most sensitive to radiation, followed by H1299 cells. In contrast, normal BEAS-2B cells were relatively radio-resistant. The imbalance of the Bcl-2/Bax ratio and the activation of caspase-3 and PARP proteins might play a key role in the anti-proliferative effects induced by 125I seeds CLDR radiation, although other possibilities have not been excluded and will be investigated in future studies

Overexpression of Phosphoserine Aminotransferase 1 (PSAT1) Predicts Poor Prognosis and Associates with Tumor Progression in Human Esophageal Squamous Cell Carcinoma

Background/Aims: Phosphoserine aminotransferase 1 (PSAT1) is over-expressed in many carcinoma tissues, however little is known regarding its expression and function in esophageal carcinogenesis. This study investigated the expression of PSAT1 in human esophageal squamous cell carcinoma (ESCC) tissues to determine the relationship between PSAT1 expression and clinicopathological factors. Methods: The expression of PSAT1 in 64 surgical resections from esophageal carcinogenesis patients was examined by quantitative RT-PCR and immunohistochemistry and the results were compared with clinicopathological factors. In vitro experiments were performed in ESCC cells overexpressing PSAT1 to measure cell viability and invasion. Tumor formation in vivowas examined by injection of tumor cells into immunocompromised mice subcutaneously. Results: PSAT1 expression was elevated in ESCC tissues compared to normal esophageal tissues. Increased PSAT1 expression was significantly associated with stage of disease, lymph node metastasis, distant metastasis and poor prognosis. In vitro, PSAT1 overexpression promoted ESCC cell proliferation and matrigel invasion. In vivo, injection of mice with ECSS cells overexpressing PSAT1 enhanced tumor formation. Western blot analysis revealed that PSAT1 upregulated the expression and/or activity of GSK3β/Snail. Conclusion: PSAT1 plays a crucial role in the development of ESCC and predicts poor survival. Therefore, PSAT1 may be a promising novel anticancer therapeutic target

MicroRNA-340 Inhibits Esophageal Cancer Cell Growth and Invasion by Targeting Phosphoserine Aminotransferase 1

Background/Aims: Emerging evidence indicates that microRNA (miR)-340 is downregulated in various human cancers, suggesting that it acts as a tumor suppressor. The aim of the present study was to evaluate the expression and role of miR-340 in human esophageal squamous cell carcinoma (ESCC). Methods: The expression of miR-340 was examined in 64 paired ESCC and adjacent non-tumor tissues by quantitative real time PCR. The effects of miR-340 on ESCC cell proliferation and metastasis were examined by MTT and Matrigel invasion assays. Tumor growth was assessed by subcutaneous inoculation of cells into BALB/c nude mice. Targets of miR-340 were identified by bioinformatics and verified by luciferase reporter assays, quantitative real-time PCR, and western blotting. Results: MiR-340 was significantly downregulated in ESCC tumor tissues compared to adjacent non-tumor tissues and in ESCC cell lines compared to esophageal endothelial cells. Overexpression of miR-340 inhibited ESCC cell growth, colony formation, and invasion, and tumor growth in a xenograft mouse model. PSAT1 was identified as a direct target of miR-340 and its ectopic expression partially reversed the miR-340 mediated inhibition of viability, invasion and EMT in ESCC cells. The expression of miR-340 was negatively correlated with that of PSAT1 in human ESCC samples. Conclusion: MiR-340 functions as a tumor suppressor by modulating the expression of PSAT1 and may contribute to the progression and invasiveness of ESCC

Clonogenic survival fraction of A549, H1299 and BEAS-2B cells irradiated with ¹²⁵I seeds and ⁶⁰Co γ-rays.

<p>A-C: the difference in the survival fraction of A549, H1299 and BEAS-2B cells between ¹²⁵I seeds CLDR radiation and ⁶⁰Co γ-ray HDR radiation. * indicates a significant difference (P<0.05) when comparing the two radiation treatments and control treatment, and # indicates a significant difference (P<0.05) when comparing ¹²⁵I seeds CLDR radiation and ⁶⁰Co γ-ray HDR radiation of the same doses. D, E: The difference in the survival fraction of the three cell lines receiving the same treatment. * indicates a significant difference (P<0.05). Bars, standard error (SE).</p

Cell cycle analysis by flow cytometry.

<p>A: G₁ arrest of A549 cells irradiated with the two radiation sources; B, C: G₂/M arrest of H1299 and BEAS-2B cells after irradiation with the two radiation sources. * indicates a significant difference (P<0.05) when comparing 2, 4, 6 and 8 Gy irradiation by the two radiation sources and control (0 Gy) treatment, and # indicates a significant difference (P<0.05) when comparing the two radiation treatments of the same dose. Bars, standard error (SE).</p

Apoptotic ratio of A549, H1299 and BEAS-2B cells irradiated with ¹²⁵I seeds CLDR radiation and ⁶⁰Co γ-ray HDR radiation.

<p>A-C: the difference in the apoptotic ratio of A549, H1299 and BEAS-2B cells receiving ¹²⁵I seeds CLDR radiation and ⁶⁰Co γ-ray HDR radiation. * indicates a significant difference (P<0.05) when comparing 2, 4, 6 and 8 Gy irradiation by the two radiation sources and control (0 Gy) treatment, and # indicates a significant difference (P<0.05) when comparing the two radiation treatments of the same doses. D, E: the difference in the apoptotic ratios of the three cell lines irradiated with ¹²⁵I seeds and ⁶⁰Co γ-rays. * indicates a significant difference (P<0.05). Bars, standard error (SE).</p

The expression of cleaved-caspase-3 and cleaved-PARP proteins in A549, H1299 and BEAS-2B cells after exposure to ¹²⁵I seeds CLDR radiation and ⁶⁰Co γ-ray HDR radiation of 4 and 8 Gy.

<p>One representative result of three independent experiments with identical results is shown.</p