A phenanthroline derivative enhances radiosensitivity of hepatocellular carcinoma cells by inducing mitochondria-dependent apoptosis

Activation of M2 macrophage autophagy by rapamycin increases the radiosensitivity of colorectal cancer xenografts

BACKGROUND

Tumor-associated macrophages (TAMs) are intimately involved in cancer radiochemotherapy resistance. However, the mechanism by which macrophages affect radiosensitivity through autophagy remains unclear. The purpose of our study was to investigate how activating autophagy in type-II macrophages (M2) by using rapamycin (RAP) would affect the radiosensitivity of colorectal cancer (CRC) xenografts.

MATERIALS AND METHODS

A nude mouse CRC model was established by injecting LoVo CRC cells. After tumor formation, supernatant from M2 cells (autophagy-unactivated), autophagy-activated M2 cells, or autophagy-downregulated M2 cells was injected peritumorally. All tumor-bearing mice were irradiated with 8-Gy X-rays twice, and the radiosensitivity of CRC xenografts was analyzed in each group.

RESULTS

The mass, volume, and microvessel density (MVD) of tumors in the autophagy-unactivated M2 group significantly increased; however, supernatant from M2 cells that were autophagy-activated by rapamycin significantly decreased tumor weight, volume, and MVD compared with negative control. Combining bafilomycin A1 (BAF-A1) with RAP treatment restored the ability of the M2 supernatant to increase tumor mass, volume, and MVD. Immunohistochemical and Western blot results showed that compared with the negative control group, supernatant from M2 cells that were not activated by autophagy downregulated the expression of Livin and Survivin in tumor tissues; activation of M2 autophagy further downregulated the protein levels.

CONCLUSIONS

Therefore, autophagy-activated M2 supernatant can downregulate the expression of the antiapoptotic genes Livin and Survivin in CRC xenografts, improving the radiosensitivity of CRC by inducing apoptosis in combination with radiotherapy and inhibiting the growth of transplanted tumors.

Newly synthesized phenanthroimidazole derivatives L082 as a safe anti-tumor and anti-injury inflammation bifunctional compound

Chemotherapy drugs exerts beneficial antitumor activity before and after cancer surgery. Post-injury complications are a potential hazard after surgical tumor resection. Inflammation caused by surgical stress is known to promote the progression of post-injury complications. Recent studies have found that chemotherapy drugs can promote post-injury inflammatory response, leading to increased post-injury complications. Imidazole derivatives have effective anticancer activity. However, the impact of post-operative inflammation caused by imidazole derivatives is unclear. In this study, two novel phenanthroimidazole derivatives (L082 and L142) were synthesized and characterized. These compounds showed significant inhibitory effects on different tumor cells. The compound L082 also inhibited liver cancer in vivo. In addition, L082 played a significant role in inhibiting the accumulation of inflammatory cells and promoting the elimination of inflammatory cells at the incision, which may be related to inhibiting the production of ROS and NO in oxidative and nitric stress. These results suggest that L082 can be used as a bifunctional drug to suppress tumors and reduce post-injury inflammation complications.

Synthesis, docking studies and antitumor activity of phenanthroimidazole derivatives as promising c-myc G-quadruplex DNA stabilizers

Phenanthroimidazole derivatives containing phenanthroline and imidazole heterocyclic aromatic rings are effective agents to inhibit tumor cell growth. Herein, halogen element-modified imidazo[4,5f][1,10]phenanthroline derivatives 1-6 (1, 4-fluorophenyl; 2, 4-chlorophenyl; 3, 4-bromobenyl; 4, 2,3-dichlorophenyl; 5, 3,4-dichlorophenyl; and 6, 2,4-dichlorophenyl) were synthesized, and their antitumor activities were investigated. All of the compounds, especially 4, exhibited an excellent inhibitory effect against nasopharyngeal carcinoma CNE-1 cells. This effect was better than that of doxorubicin. Compound 4 also markedly blocked the proliferation of the CNE-1 cells in a zebrafish xenograft model. The antitumor mechanisms might be attributed to apoptosis induction, which triggered ROS-mediated DNA damage and generated mitochondrial dysfunction by stabilizing c-myc G-quadruplex DNA structure. Results indicated that phenanthroimidazole derivatives could act as promising anticancer agents.

Novel role of PAF1 in attenuating radiosensitivity in cervical cancer by inhibiting IER5 transcription

Background

Radiosensitivity is limited in cervical cancer (CC) patients due to acquired radiation resistance. In our previous studies, we found that immediate-early response 5 (IER5) is upregulated in CC cells upon radiation exposure and decreases cell survival by promoting apoptosis. The details on the transcriptional regulation of radiation-induced IER5 expression are unknown. Studies in recent years have suggested that Pol II-associated factor 1 (PAF1) is a pivotal transcription factor for certain genes “induced” during tumor progression. In this study, we investigated the role of PAF1 in regulating IER5 expression during CC radiotherapy.

Methods

PAF1 expression in CC cells was measured by western blotting, immunohistochemistry, and qRT-PCR, and the localization of PAF1 and IER5 was determined by immunofluorescence. The effect of PAF1 and IER5 knockdown by siRNA in Siha and Hela cells was studied by western blotting, qRT-PCR, CCK-8 assay, and flow cytometry. The physical interaction of PAF1 with the IER5 promoter and enhancers was confirmed using chromatin immunoprecipitation and qPCR with or without enhancers knockout by CRISPR/Cas9.

Results

We confirmed that PAF1 was highly expressed in CC cells and that relatively low expression of IER5 was observed in cells with highly expressed PAF1 in the nucleus. PAF1 knockdown in Siha and Hela cells was associated with increased expression of IER5, reduced cell viability and higher apoptosis rate in response to radiation exposure, while simultaneous PAF1 and IER5 knockdown had little effect on the proportion of apoptotic cells. We also found that PAF1 hindered the transcription of IER5 by promoting Pol II pausing at the promoter-proximal region, which was primarily due to the binding of PAF1 at the enhancers.

Conclusions

PAF1 reduces CC radiosensitivity by inhibiting IER5 transcription, at least in part by regulating its enhancers. PAF1 might be a potential therapeutic target for overcoming radiation resistance in CC patients.

Sanguinarine inhibits the proliferation of BGC-823 gastric cancer cells via regulating miR-96-5p/miR-29c-3p and the MAPK/JNK signaling pathway

Sanguinarine (SAN), a quaternary benzophenanthridine alkaloid extracted from the root of Papaveraceae plants, has shown antitumour effects in multiple cancer cells. However, the therapeutic effects and the underlying mechanisms of SAN in gastric cancer (GC) remain elusive. In this study, the in vitro proliferation inhibition effect of SAN in GC cells was determined using CCK-8 assay, the in vivo antitumor effect of SAN was evaluated in mice with xenotransplanted tumor. The mechanism underlying the antitumor activity of SAN was explored by gene microarray assay and bioinformatics analysis. The levels of differentially expressed miRNAs and target genes were verified by real-time RT-PCR and immunohistochemistry. SAN inhibited the proliferation of BGC-823 cells in a concentration-dependent manner in vitro and in vivo. The miR-96-5p and miR-29c-3p were significantly upregulated in untreated BGC-823 cells and significantly downregulated in SAN treated cells. The mRNA and protein expression of their target gene MAP4K4 were upregulated in SAN treated xenotransplanted tumors, and pMEK4 and pJNK1 proteins in the MAPK/JNK signaling pathway were also upregulated by SAN. These indicate that SAN may inhibit the proliferation of BGC-823 cells through the inhibition of miR-96-5p and miR-29c-3p expression, and subsequent activation of the MAPK/JNK signaling pathway.