Tubeimoside-1 induces TFEB-dependent lysosomal degradation of PD-L1 and promotes antitumor immunity by targeting mTOR

Programmed cell death ligand 1 (PD-L1)/programmed cell death protein 1 (PD-1) cascade is an effective therapeutic target for immune checkpoint blockade (ICB) therapy. Targeting PD-L1/PD-1 axis by small-molecule drug is an attractive approach to enhance antitumor immunity. Using flow cytometry-based assay, we identify tubeimoside-1 (TBM-1) as a promising antitumor immune modulator that negatively regulates PD-L1 level. TBM-1 disrupts PD-1/PD-L1 interaction and enhances the cytotoxicity of T cells toward cancer cells through decreasing the abundance of PD-L1. Furthermore, TBM-1 exerts its antitumor effect in mice bearing Lewis lung carcinoma (LLC) and B16 melanoma tumor xenograft

Cholesterol-associated lysosomal disorder triggers cell death of hematological malignancy: Dynamic analysis on cytotoxic effects of LW-218

The integrity of lysosomes is of vital importance to survival of tumor cells. We demonstrated that LW-218, a synthetic flavonoid, induced rapid lysosomal enlargement accompanied with lysosomal membrane permeabilization in hematological malignancy. LW-218-induced lysosomal damage and lysosome-dependent cell death were mediated by cathepsin D, as the lysosomal damage and cell apoptosis could be suppressed by depletion of cathepsin D or lysosome alkalization agents, which can alter the activity of cathepsins. Lysophagy, was initiated for cell self-rescue after LW-218 treatment and correlated with calcium release and nuclei translocation of transcription factor EB. LW-218 treatment enhanced the expression of autophagy-related genes which could be inhibited by intracellular calcium chelator. Sustained exposure to LW-218 exhausted the lysosomal capacity so as to repress the normal autophagy. LW-218-induced enlargement and damage of lysosomes were triggered by abnormal cholesterol deposition on lysosome membrane which caused by interaction between LW-218 and NPC intracellular cholesterol transporter 1. Moreover, LW-218 inhibited the leukemia cell growth

Berberine diminishes cancer cell PD-L1 expression and facilitates antitumor immunity

Programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) blocking therapy has become a major pillar of cancer immunotherapy. Compared with antibodies targeting, small-molecule checkpoint inhibitors which have favorable pharmacokinetics are urgently needed. Here we identified berberine (BBR), a proven anti-inflammation drug, as a negative regulator of PD-L1 from a set of traditional Chinese medicine (TCM) chemical monomers. BBR enhanced the sensitivity of tumour cells to co-cultured T-cells by decreasing the level of PD-L1 in cancer cells. In addition, BBR exerted its antitumor effect in Lewis tumor xenograft mice through enhancing tumor-infiltrating T-cell immunity and attenuating the activation of immunosuppressive myeloid-derived suppressor cells (MDSCs) and regulatory T-cells (Tregs). BBR triggered PD-L1 degradation through ubiquitin (Ub)/proteasome-dependent pathway. Remarkably, BBR selectively bound to the glutamic acid 76 of constitutive photomorphogenic-9 signalosome 5 (CSN5) and inhibited PD-1/PD-L1 axis through its deubiquitination activity, resulting in ubiquitination and degradation of PD-L1. Our data reveals a previously unrecognized antitumor mechanism of BBR, suggesting BBR is small-molecule immune checkpoint inhibitor for cancer treatment.

The Change of Hearing Threshold and Endocochlear Potential by Bafilomycin Delivered to Round Window in Guinea Pigs / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Vacuolar type H+-ATPase (V-H+-ATPase) has a role in the regulation of endolymphatic pH and certain cells (including strial marginal cells, inner hair cells and epithelial cells of the endolymphatic sac) may be specialized for this regulation. Bafilomycin is a specific V-H+-ATPase inhibitor affecting inner ear function by controlling the intracytolic pH decrease. We designed the study to analyze the effect of bafilomycin delivered to the inner ear on the hearing threshold measured by auditory brainstem response (ABR) and endolymphatic potential (EP). MATERIALS AND METHOD: For measuring the hearing threshold change, 13 guinea pigs with normal Preyer's reflex and normal ABR were used. Guinea pigs were randomly divided into control group (n=3, 6 ears) and study groups which were subdivided into the following ;1 mM bafilomycin group (n=3, 6 ears), 5 mM bafilomycin group (n=3, 6 ears) and 10 mM bafilomycin group (n=4, 8 ears). The mastoid cavity was opened to expose the round window and HBSS buffer (300 osm) was applied for the control group and bafilomycin with different concentrations were also applied to the round windows of studied guinea pigs. The hearing threshold was measured using ABR before and after the application of appropriate solutions. For measuring of EP, the cochlea helix and round window of guinea pig with normal hearing were defined and a tungsten micro needle was inserted into the endolymphatic space at 2nd turn of guinea pig's cochlea. EP was measured after application of HBSS buffer as control, 1 mM, 5 mM, and 10 mM bafilomycin. RESULTS: In the control group, the hearing threshold was 21.6+/-2.8 dB (mean+/-SD) initially both before and after mastoidectomy and stayed that way all throughout the study. The hearing threshold increased as bafilomycin was applied. For 1 mM of bafilomycin application, the threshold changed from initial 30.0+/-5 dB to 33.3+/-5.7 dB after 2 hours. For 5 mM of bafilomycin application, the threshold changed after 2 hours from initial 30.0+/-5 dB to 50.0+/-0 dB. With 10 mM of bafilomycin application, the threshold changed after 2 hours from initial 27.5+/-6.4 dB to 52.5+/-8.6 dB. For 5 mM and 10 mM bafilomycin group, there was a significant statistical change of hearing threshold (p<0.05). However, there was no meaningful difference between 5 mM and 10 mM group (p=0.88). Initial EP was 85+/-10 mV and was significantly decreased in 5 mM (35 mV) and 10 mM (19.8 mV) bafilomycin groups, but such was not observed in 1 mM bafilomycin and control group. CONCLUSION: We could observe the elevation of hearing threshold and decrease EP after applying bafilomycin on the round windows of guinea pigs and also observed that this change reached a critical point when the concentration of bafilomycin was 5 mM or higher. From these results, we can conclude that bafilomycin does affect the hearing threshold through its mechanism and the degree of damage has a critical point dependent on the concentration of bafilomycin.