siRNA-induced CD44 knockdown suppresses the proliferation and invasion of colorectal cancer stem cells through inhibiting epithelial-mesenchymal transition.

CD44 has shown prognostic values and promising therapeutic potential in multiple human cancers; however, the effects of CD44 silencing on biological behaviors of cancer stem cells (CSCs) have not been fully understood in colorectal cancer. To examine the contribution of siRNA-induced knockdown of CD44 to the biological features of colorectal CSCs, colorectal CSCs HCT116-CSCs were generated, and CD44 was knocked down in HCT116-CSCs using siRNA. The proliferation, migration and invasion of HCT116-CSCs were measured, and apoptosis and cell-cycle analyses were performed. The sensitivity of HCT116-CSCs to oxaliplatin was tested, and xenograft tumor growth assay was performed to examine the role of CD44 in HCT116-CSCs tumorigenesis in vivo. In addition, the expression of epithelial-mesenchymal transition (EMT) markers E-cadherin, N-cadherin and vimentin was quantified. siRNA-induced knockdown of CD44 was found to inhibit the proliferation, migration and invasion, induce apoptosis, promote cell-cycle arrest at the G1/G0 phase and increase the sensitivity of HCT116-CSCs to oxaliplatin in HCT116-CSCs, and knockdown of CD44 suppressed in vivo tumorigenesis and intrapulmonary metastasis of HCT116-CSCs. Moreover, silencing CD44 resulted in EMT inhibition. Our findings demonstrate that siRNA-induced CD44 knockdown suppresses the proliferation, invasion and in vivo tumorigenesis and metastasis of colorectal CSCs by inhibiting EMT.

All-optical microwave oscillator based on a mutual-injection coupling between DFB-LDs.

An all-optical microwave oscillator (AOMO) is proposed and experimentally demonstrated. It contains only a mutual injection loop consisting of two distributed feedback laser diodes (DFB-LDs) and a few passive components. In this AOMO, the microwave seed signal originates from the period-one (P1) oscillation in one of the DFB-LDs. The functions of microwave envelope detection and feedback modulation are implemented by the other DFB-LD. Due to the optical injection locking and the optical-optical modulated effect in DFB-LD, the P1 signal is enhanced, and the stability of the P1 signal can be improved by coupling the P1 signal with a resonant mode of the mutual injection loop. Meanwhile, since the P1 oscillation is sensitive to injected light, the frequency of the P1 signal can be easily adjusted, which makes the AOMO easy to be tuned. In the experiment, a highly stable single-mode microwave signal with a frequency of 16.69 GHz and a single-sideband (SSB) phase noise of -90.7 dBc/Hz@10 kHz is generated. The frequency can be tuned from 14.48 to 21.45 GHz by adjusting the parameters of DFB-LDs and the injection light.

Photonic microwave waveforms generation based on two cascaded single-drive Mach-Zehnder modulators.

A new photonic scheme for various waveforms generation has been proposed and demonstrated. In the scheme, two cascaded single-drive LiNbO3 Mach-Zehnder modulators serve as pulse shaper and the polarization-dependent character of the modulators is fully exploited and utilized. By arranging the polarization states of the incident light, two different spectra are achieved on two orthogonal polarization components respectively. Finally, the desired waveforms can be obtained by superimposing the photocurrents of the two orthogonal signals on a photodetector. The detailed theoretical analyses and simulations are given. In the experiment, square-shaped waveform, triangular waveform and sawtooth (or reversed-sawtooth) waveform are obtained successfully. Furthermore, an approach to smoothing the sawtooth waveform with fewer harmonics is suggested and verified.

All-optical microwave oscillator based on semiconductor optical amplifier and stimulated Brillouin scattering.

An all-optical microwave oscillator is proposed and experimentally demonstrated. Based on a pure photonic feedback loop, this system can generate a photonic microwave signal without optical-electrical-optical conversion or any electrical microwave devices. A semiconductor optical amplifier implements the functions of microwave envelope detection and feedback modulation. Meanwhile, Brillouin-selective sideband amplification is employed to lock oscillation frequency. In experiment, a good quality microwave signal with a frequency of 10.8 GHz is obtained. The tunability is also demonstrated by adjusting the Brillouin pump wavelength.

Photonic microwave waveforms generation based on time-domain processing.

A new photonic approach of microwave waveform generator based on time-domain synthesis is proposed and experimentally demonstrated, in which two single-drive Mach-Zehnder modulators biased at quadrature point are severed as optical pulse carvers and various microwave waveforms can be generated by carving and overlapping optical field envelopes. The theoretical analysis and simulation are developed. In experiment, a square waveform with 50% duty cycle, triangular waveform with full duty cycle, and sawtooth (or reversed-sawtooth) waveform with 50% duty cycle are generated. Furthermore, a frequency doubling sawtooth (or reversed-sawtooth) waveform with full duty cycle is also obtained.