[Impacts of hypoxia on the features and chemoresistance of cancer stem cells in Hep-2 cells and underlying mechanism]

OBJECTIVE

To investigate the effects of hypoxia on the features and chemoresistance of cancer stem cells in Hep-2 cells and underlying mechanism.

METHODS

The shRNA interference recombinant plasmid targeting HIF-1α was synthesized and transfected into Hep-2 cells. The HIF-1α knockdown Hep-2 cells were established after clonal selection and the expression of HIF-1α was measured. The cellular features including proliferation, clonal formation, cell cycle, apoptosis and CD133 phenotype were measured in Hep-2 cells cultured under hypoxic condition in vitro. CD133+ cells were sorted from Hep-2 cells with flow cytometry. Clonal formation test and cisplatin treatment were carried out, and the expressions of related genes (Oct-4, suvivin and p53) in CD133+ cells were measured.

RESULTS

HIF-1α knockdown Hep-2 cells was successfully established, as evidenced by the reduced mRNA and protein expressions of HIF-1α. The Hep-2 cells cultured under hypoxic microenvironment showed higher proliferation and clonal formation activity, cell cycle arrest in G0/G1, lower apoptosis, up-regulated CD133, however the effects of hypoxia reduced in HIF-1α knockdown Hep-2 cells. CD133+ cells were successfully sorted from Hep-2 cells, and the CD133+ cells showed increased clonal formation activity and cisplatin treatment resistance in hypoxia. Also the effects of hypoxia on CD133+ cells decreased with HIF-1α knockdown, showing down-regulated Oct-4 and survivin and up-regulated p53.

CONCLUSIONS

Hypoixa can induce the features of cancer stem cells in Hep-2 cells and increase proliferation, differentiation and chemoresistant ability of CD133+ cells, which might be correlated with the changes in expressions of HIF-1α and related genes regulated by HIF-1α.

[Cancer stem cells play an important role in resistance of laryngeal squamous cancer to irradiation mediated by hypoxia]

OBJECTIVE

To study whether laryngeal cancer stem cells in hypoxia have the characteristic of resistance to irradiation and underlying mechanism.

METHODS

CD133(+) cells were separated from Hep-2 cells with flow cytometry (FCM) and the purity was 92.8%. The separated CD133(+) cells were cultured in serum-free medium in hypoxia in normoxia environment respectively, and hypoxia-inducible factor 1 alpha (HIF-1α) expression was detected by FCM. The cells were exposed respectively to X-rays emitted by linear accelerator with a dose of 0, 5, 10, 15 or 20 Gy for 24 hours, with additional time points of 12, 36, and 48 hours for the cells exposed to 10 Gy. Then the growth inhibition ratios of cells in hypoxia and normoxia groups were detected with MTT assay at different time points. Soft agar colony formation assay was used to detect colony formation ratios of cells in hypoxia and normoxia groups. DNA dependent protein kinase catalytic subunit (DNA-PKcs), ataxia telangiectasia mutate (ATM), Survivin and P53 were detected by FCM.

RESULTS

Growth inhibition ratio of CD133(+) cells in hypoxia group was lower than that in normoxia group (P < 0.05). Colony formation ratio of CD133(+) cells was higher than that of CD133(-) cells (P < 0.01) and the ratio of CD133(+) cells in hypoxia group was higher than that in normoxia group (P < 0.05). The ratio of hypoxia group was not affected by irradiation, while the ratio of normoxia group decreased significantly after irradiation (P < 0.05). The expressions of DNA-PKcs, ATM, Survivin and P53 in CD133(+) cells were higher than those in CD133(-) cells respectively (P < 0.01). In CD133(+) cells with radiation, the expressions of DNA-PKcs and Survivin of hypoxia group were higher those of normoxia group (P < 0.05), but no difference in the expression of ATM or P53 between the two groups.

CONCLUSIONS

Laryngeal cancer stem cells play an important role in radioresistance mediated by hypoxia.

[Cancer stem cells promotes resistance of laryngeal squamous cancer to irradiation mediated by hypoxia]

OBJECTIVE

To study whether cancer stem cells promotes resistance of laryngeal squamous cancer to irradiation mediated by hypoxia.

METHOD

Hep-2 cells were respectively cultured in hypoxia and normoxia environment, and the express of HIF-la was detected by western blot. Then they were radiated with different doses of gamma-rays. After that we detected growth inhibition ratio with MTT assay, cell circle and ratio of CD133+ cells with Flow cytometry at different times.

RESULT

MTT assay showed that inhibition ratio of the hypoxia group was lower than that of the normoxia group after different doses of gamma-rays at each time point, and the difference was significant 24 h after 10 Gy irradiation (P < 0.05). The results of Flow cytometry demonstrated that cells of the two groups were arrested at G1 phase, and cells ratio in G1 phase of the hypoxia group was higher than that of he normoxia group after 10 Gy irradiation. The ratio of CD133-positive cells was higher in the hypoxia group than in the normoxia group after radiation, and difference was significant 24 h after 10 Gy irradiation (P < 0.05). In each group, the ratio of CD133-positive cells became higher after radiation than that before radiation (P < 0. 05).

CONCLUSION

We can conclude that cancer stem cells play an important role in radioresistance mediated by hypoxia.

Protective effects of Salvia miltiorrhiza against cisplatin-induced ototoxicity in guinea pigs

OBJECTIVE

The aim of the study was to investigate the protective effects of Salvia miltiorrhiza (SM) against cisplatin-induced ototoxicity in guinea pigs.

METHODS

Thirty-nine guinea pigs were randomly divided into 3 groups. The first group (control group) received physiologic saline by intraperitoneal (i.p.) injection for 5 days. The second group (cisplatin group) was treated with cisplatin (2 mg/kg per day, i.p. injection) for 5 days. The third group (SM group) was given SM (8 g/kg per day, i.p. injection) for 2 days and then was given SM (8 g/kg per day, i.p. injection) and cisplatin (2 mg/kg per day, i.p. injection) for 5 days. Auditory brain stem response (ABR) and cochlea blood flow measurement were used to evaluate cochlea function. The structures of cochlea were observed by light microscope, scanning electron microscope, transmission electron microscope (TEM), and immunohistochemical examination.

RESULTS

Cisplatin could cause severe acoustic damages including significant elevation of ABR threshold, substantial losses of outer hair cells and inner hair cells, and severe damage on the stria vascularis and spiral ganglion cells (SGCs). Although in SM group, the increased tendency of threshold was milder than that in cisplatin group. The damages in cochlea and stria vascularis were also less severe than those in cisplatin group. The expression of induced nitric oxide synthase in the cochlea and SGC in SM group was lower than that in cisplatin group.

CONCLUSIONS

Salvia miltiorrhiza can significantly reduce the cisplatin-induced side effects.

Proposal and analysis of two-cavity Fabry-Perot structures based on fiber Bragg gratings

An all-fiber two-cavity Fabry-Perot (FP) configuration based on fiber Bragg gratings (FBGs) is proposed. The characteristics of transmission spectra for the two-cavity FP structure are theoretically analyzed and comprehensively modeled. The explicit expression of the transmission coefficient for the structures is derived. The general conditions for the lengths of two cavities and reflectivities of FBGs are presented to produce the single resonant transmission peak at the central wavelength in the FBG stop band. Based on the theoretical analysis, the transmission spectra of symmetric and asymmetric two-cavity FP structures are simulated, and the simulation results are discussed and explained qualitatively. The design guidelines of the device, including the choices of cavity lengths, grating lengths, and index modulation depths, are concluded. The results show that when the increasing of the cavity length of a single-cavity FP structure results in multiple resonant peaks in the stop band, the two-cavity FP structures of the same length can inhibit the secondary resonant peaks and keep the main peak without degrading the performance through appropriately designing the cavity lengths and FBGs. Finally, the fabrication error tolerances of the structures, including inaccurate cavity lengths and reflectivities of FBGs, are calculated and discussed.

Analysis of radiation-mode coupling in reflective and transmissive tilted fiber Bragg gratings

Radiation-mode coupling is stronger and more efficient in tilted fiber Bragg gratings than in other fiber gratings; it can be used to good advantage in such fields as optical communication and optical sensors. A simplified coupled-mode theory (CMT) approach to the analysis of radiation-mode coupling is proposed for what we believe to be the first time, whose validity and accuracy is demonstrated by comparing its simulation results with that of the complete CMT equations and the volume current method (VCM). With the simplified CMT approach, a theoretical spectral analysis of coupling from core mode to radiation modes in both reflective and transmissive tilted fiber Bragg gratings is presented. The influence of tilt angle on the transmission spectrum characteristics is comprehensively investigated. The different dependences between s-polarized and p-polarized radiation-mode coupling on grating tilt angle are discussed, and an analysis is performed on how to obtain a high-performance in-fiber polarizer that involves a compromise between polarization extinction and insertion loss.

Single-polarization, switchable dual-wavelength erbium-doped fiber laser with two polarization-maintaining fiber Bragg gratings

An improved erbium-doped fiber laser configuration for achieving single-polarization, switchable dual-wavelength of orthogonal polarizations oscillations at room temperature is proposed. For the first time, two fiber Bragg gratings (FBGs) directly written in a polarization-maintaining (PM) and photosensitive erbium-doped fiber (PMPEDF) as the wavelength-selective component are used in a linear laser cavity. Due to the polarization hole burning (PHB) enhanced by the polarization-maintaining FBG (PMFBG), the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). Each lasing line shows a single polarization with a polarization extinction ratio of >25 dB under different pump levels. The optical signal-to-noise ratio (OSNR) is greater than 50 dB. The amplitude variation with 16 times scans in nearly one and half an hour is less than 0.5 dB at both operating wavelength.

[The application of the magnetic resonance hydrography of inner ear in diagnosing large vestibular aqueduct syndrome]

OBJECTIVE

To study the effect of the magnetic resonance hydrography of inner ear technique in diagnosing large vestibular aqueduct syndrome.

METHOD

3D-Fast Advanced Spin Echo MR imaging was performed on the petrosal bone of the patient who suffered from large vestibular aqueduct syndrome(LVAS). Then all the original images were transferred to an online workstation and underwent image postprocessing. The 3D images of the inner ears were obtained after 3D reconstruction.

RESULT

The MR hydrography of inner ear of the patient displayed that there was an extradural high-signal intumescence which was like silver shape and the edge of it was smooth and neat between the sigmoid sinus of the posterior cranial fossa and the inner acoustic meatus. The maximum width of the mid position of endolymphatic sac in the temporal bone of the patient was 2.470 mm. This was much bigger than the diagnosis standard of the large vestibular aqueduct syndrome with ordinary MR imaging.

CONCLUSION

The MR hydrography technique is an effective method to diagnose large vestibular aqueduct syndrome. The final diagnosis in clinic could be made with the assistance of this technique.

[Effect of combination of Ginkgo leaf extract and deferoxamine in preventing and treating ototoxicity of cisplatin]

OBJECTIVE

To observe the effect of combined use of jinnaduo (an injection made by extract of Ginkgo leaf, EGb) and Deferoxamine (DFO, a chelating agent) in antagonizing the ototoxicity of cisplatin (CDDP).

METHODS

Guinea pigs were randomly divided into the CDDP group, the EGb group, the DFO group, the combined treated group (EGb + DFO) and the control group. Changes of auditory brain-stem response (ABR), serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, as well as light and scanning electronic microscopic (SEM) figures were observed before and after treatment.

RESULTS

The threshold of ABR was significantly higher in the CDDP group than that in the other groups (P<0.01), but was insignificantly different among the latter groups (P>0.05). Serum SOD activity was lower and MDA content was higher in the CDDP group than those in the control group (P<0.01), but in comparison of the two parameters between control and other groups, the difference was insignificant (P>0.05). SEM examination on cochlea showed that the damage of hair cells was milder in the DFO group and the combined treated group than that in the CDDP group, which was slightly milder in the EGb group than that in the CDDP group.

CONCLUSION

Combined use of EGb and DFO could effectively reduce the ototoxicity of CDDP, its effect is better than using EGb singly, and similar to that of using DFO alone. The combination could also prevent the side-effect of CDDP in bone marrow inhibition. The Fe ion participated free radical response could be one of the mechanisms of CDDP in damaging hearing.