STAT3 inhibitor stattic enhances radiosensitivity in esophageal squamous cell carcinoma.

The radioresistance of esophageal squamous cell carcinoma (ESCC) remains an obstacle for the effective radiotherapy of ESCC. This study aimed to investigate the radiosensitization of ESCC by signal transducer and activator of transcription 3 (STAT3) inhibitor stattic. ECA109, TE13, and KYSE150 cell lines were exposed to hypoxia and treated with stattic or radiation, alone or in combination. Cell proliferation, colony formation, apoptosis, and double-stranded DNA breaks (DSBs) were examined. In addition, ECA109 cells were xenografted into nude mice and treated with radiation and/or stattic. The levels of STAT3, p-STAT3, hypoxia-inducible factor 1α (HIF-1α), and vascular endothelial growth factor (VEGF) in ESCC cells and xenografts were detected by Western blot and immunohistochemical analysis. Our results showed that stattic efficiently radiosensitized ESCC cells and xenografts, especially under hypoxia. Moreover, stattic inhibited STAT3 activation and downregulated HIF-1α and VEGF expression. In conclusion, stattic confers radiosensitivity in ESCC cells in vitro and in vivo and is a potential adjuvant for the radiotherapy of ESCC in the clinical setting.

Management and Outcomes of Patients With Radiotherapy Interruption During the COVID-19 Pandemic.

PURPOSE: This retrospective observational study examined patients who experienced radiotherapy (RT) interruption during the Wuhan lockdown for the novel coronavirus disease 2019 (COVID-19) pandemic. MATERIALS AND METHODS: The data of all patients whose RT was interrupted during the Wuhan lockdown from January 23 to April 8, 2020 were collected. Patient-, cancer-, and treatment-related characteristics were analyzed, along with interruption time, disease progression type, and survival status. The methods employed in order to compensate for RT interruption were also described. RESULTS: There were altogether 129 cancer patients whose RT was interrupted. Nineteen (14.7%) patients experienced a total interruption time of at most 7 days; the interruption time was 8-14 days for 27 (20.9%) patients, and 15 or more days for 47 (36.4%) patients. The remaining 36 (27.9%) patients did not come back to our hospital for further RT. We first describe our experience with re-immobilization and/or re-planning (n = 17) as well as dose compensation/adjustment. Of the 40 definitive radiotherapy patients, 37 had squamous cell carcinoma of nasopharyngeal, lung, or cervical origin. Most patients (85/93, 91.4%) were followed up for more than one year. Among the 40 patients who received definitive radiotherapy, nine patients experienced disease progression and five patients died. Three of the seven (42.9%) patients who did not finish radiotherapy after interruption died, as compared to only two of the 33 (6.1%) patients who completed radiotherapy. EQD2 (equivalent dose in 2 Gy fractions) at the time point of RT interruption was calculated. Five of the six patients (83.3%) who received EQD2 ≤10 Gy suffered from disease progression, compared with four of the 34 (11.8%) patients who received EQD2 >10 Gy. For the seven definitive radiotherapy cases who did not finish radiotherapy, three received systemic anti-cancer treatments and three died (all of whom did not receive further systemic therapies). CONCLUSIONS: This study provides the longest follow-up for the outcomes of RT interruption during COVID-19 pandemic to date. It cannot imply causation but implies that completing RT is important, along with the utility of having patients remain on systemic therapies if RT is to be interrupted.

Telomere length inversely correlates with radiosensitivity in human carcinoma cells with the same tissue background.

A relationship between telomeres and radiosensitivity has been established by several studies based on non-mammalian model systems, mouse models, and few human genetic diseases. However, the relationship has not been proven in human carcinoma cells, which have more clinical significance than these other models. The present study aims to determine whether telomere length is related to radiosensitivity in human carcinoma cells, and to examine the influence of tissue or genetic background. Two HEp-2 larynx squamous carcinoma cell lines, eight hepatocellular carcinoma cell lines, and five breast cancer cell lines were used. Telomere length was determined by terminal restriction fragment (TRF) Southern blot analysis and cell survival was measured by a colony-forming assay. Our results indicated that there was a significant negative correlation of telomere length and radiosensitivity in the same tissue-derived cell lines, with or without the same genetic background. Thus, telomere length may be used as a promising tool to predict the radiosensitivity of human carcinomas.

[Correlations of telomere length and telomerase activity to radiosensitivity of human laryngeal squamous carcinoma cells].

BACKGROUND & OBJECTIVE: Many studies showed that telomere length and telomerase activity closely correlate with proliferation and malignant degree of tumor cells, and both of them might be involved in the repair of radiation-induced DNA damage. So it was speculated that telomere length and telomerase activity maybe correlate to radiosensitivity of carcinoma cells. This study was designed to investigate the correlations of telomere length and telomerase activity to radiosensitivity of human laryngeal squamous carcinoma cell line Hep-2. METHODS: Hep-2 cells were irradiated with 0, 2, 4, 8, or 12 Gy of gamma-ray for 3 times. Survival cells were subcultured for 20 generations. Radiosensitivity index, survival fraction at 2 Gy (SF(2)), was measured by clone formation assay. Telomere length (mean length of telomere restriction fragments, TRF) was examined by Southern blotû telomerase activity (TA) was detected by polymerase chain reaction-based telomeric repeat amplification protocol (PCR-TRAP) coupled with ELISA. RESULTS: After different doses of irradiation, SF(2) of Hep-2 cells was 0.47-0.64; TRF was 3.76-9.43 kb; TA was 1.761-2.606. Each parameter had significant differences among the survival progenies (P<0.05). SF(2) was positively correlated with TRF (r=0.921, P<0.01), and negatively correlated with TA (r=-0.929, P<0.01); TRF was negatively correlated with TA (r=-0.944, P<0.01). CONCLUSION: Radiosensitivity of Hep-2 cells negatively correlates with telomere length, and positively correlates with telomerase activity, which suggest that both telomere length and telomerase activity may be used to predict cellular radiosensitivity.