HIF-1α overexpression is associated with radio-resistance of various cancers. A radioresistant human melanoma cell model MDA-MB-435R (435R) was established by us previously. Compared with the parental cells MDA-MB-435 (435S), an elevated level of HIF-1α expression in 435R cells was demonstrated in our recent experiments. Therefore, in the current study, we sought to determine whether selective HIF-1α inhibitors could radiosensitize the 435R cells to X-ray, and to identify the potential mechanisms. Our data demonstrated that inhibition of HIF-1α with 2-methoxyestradiol (2-MeOE2) significantly enhanced radiosensitivity of 435R cells. 2-MeOE2 increased DNA damage and ratio of apoptosis cells induced by irradiation. Whereas, cell proliferation and the expression of pyruvate dehydrogenase kinase 1 (PDK1) were decreased after 2-MeOE2 treatment. The change of expression of GLUT1, LDHA and the cellular ATP level and extracellular lactate production indicates that 2-MeOE2 suppressed glycolytic state of 435R cells. In addition, the radioresistance, glycolytic state and cell proliferation of 435R cells were also decreased after inhibiting pyruvate dehydrogenase kinase 1 (PDK1) with dichloroacetate (DCA). DCA could also increase DNA damage and ratio of apoptotic cells induced by irradiation. These results also suggest that inhibition of HIF-1α with 2-MeOE2 sensitizes radioresistant melanoma cells 435R to X-ray irradiation through targeting the glycolysis that is regulated by PDK1. Selective inhibitors of HIF-1α and glycolysis are potential drugs to enhance radio sensitivity of melanoma cells.

Although papillary renal cell carcinoma (PRCC) accounts for 10%–15% of renal cell carcinoma (RCC), no predictive molecular biomarker is currently applicable to guiding disease stage of PRCC patients. The mRNASeq data of PRCC and adjacent normal tissue in The Cancer Genome Atlas was analyzed to identify 1148 differentially expressed genes, on which weighted gene co-expression network analysis was performed. Then 11 co-expressed gene modules were identified. The highest association was found between blue module and pathological stage (r = 0.45) by Pearson's correlation analysis. Functional enrichment analysis revealed that biological processes of blue module focused on nuclear division, cell cycle phase, and spindle (all P < 1e-10). All 40 hub genes in blue module can distinguish localized (pathological stage I, II) from non-localized (pathological stage III, IV) PRCC (P < 0.01). A good molecular biomarker for pathological stage of RCC must be a prognostic gene in clinical practice. Survival analysis was performed to reversely validate if hub genes were associated with pathological stage. Survival analysis unveiled that all hub genes were associated with patient prognosis (P < 0.01). The validation cohort GSE2748 verified that 30 hub genes can differentiate localized from non-localized PRCC (P < 0.01), and 18 hub genes are prognosis-associated (P < 0.01).ROC curve indicated that the 17 hub genes exhibited excellent diagnostic efficiency for localized and non-localized PRCC (AUC > 0.7). These hub genes may serve as a biomarker and help to distinguish different pathological stages for PRCC patients.

Abstract. Homeobox containing 1 (HMBOX1) modulates telomere length in various types of tumor cells by binding to double-stranded telomeric DNA. There is a negative correlation between telomere length and radiosensitivity in tumor cells. In the present study, we aimed to investigate the relationship among HMBOX1, telomere and radiosensitivity in cervical cancer cells. Lentivirus-based shRNAs were used to establish stable transfected cell lines in which protein and mRNA levels of HMBOX1 were notably decreased. Knockdown of HMBOX1 increased the radiosensitivity of HeLa and C33A cells. TERT protein was also decreased while HMBOX1 was downregulated. Knockdown of HMBOX1 shortened telomere length in the HeLa cells, while TERT overexpression rescued telomere shortening in the HeLa-HMBOX1 cells. Knockdown of HMBOX1 increased the apoptosis rate, decreased radiationinduced DNA damage foci, and inhibited the expression of ATM, ATR, p-ATM, p-ATR and BRCA1 in the homologous recombination repair pathway. Our data suggest a possible role of HMBOX1 in regulating radiosensitivity in cervical cancer cells. Moreover, HMBOX1 may be a potential factor in the radiotherapy of cervical cancer. IntroductionCervical cancer is the most common malignant tumor of the female reproductive system. It is the second most commonly diagnosed cancer and the third leading cause of cancerrelated death among females in developing countries (1). Radiotherapy is the major treatment for cervical cancer. For patients with early-stage disease, radiotherapy and surgery alone have equal effects. In recent years, chemoradiotherapy has gradually become a new treatment pattern for patients with locally advanced disease. It has been demonstrated that radiotherapy plays a crucial role in the treatment of cervical cancer. However, patients who suffer pelvic recurrence account for ~70% of the cases of radiotherapy failure (2). Thus, the identification of new factors that influence radiosensitivity has important significance in cervical cancer treatment.Homeobox containing 1 (HMBOX1), a new member of the homeobox genes, was identified and isolated from the human pancreatic cDNA library. HMBOX1 was described as a transcription repressor (3). In the ALT (alternative lengthening of telomeres) cell line WI38-VA13 and telomerase-positive HeLa cells, HMBOX1 was identified as a double-stranded telomeric DNA binding protein (4) and acted as a positive regulator of telomere length (5). In U2OS (ALT cells), HMBOX1 was found to modulate telomere maintenance without influencing telomere length (6). However, the further function of HMBOX1 is not fully clear.Telomeres, nucleoprotein complexes at the end of eukaryotic chromosomes, are composed of 5'-TTAGGG-3' repeats and are maintained by telomerase. Telomeres contain protein complexes and shelterin, and play a crucial role in protecting chromosome ends from DNA damage. Moreover, telomere length may serve as a target in predicting the individual radiosensitivity of patients with cancers (7-11).However, to date, the relationship bet...