The regulatory role of autophagy between TAMs and tumor cells.

Cancer has become a global public health problem and its harmful effects have received widespread attention. Conventional treatments such as surgical resection, radiotherapy and other techniques are applicable to clinical practice, but new drugs are constantly being developed and other therapeutic approaches, such as immunotherapy are being applied. In addition to studying the effects on individual tumor cells, it is important to explore the role of tumor microenvironment on tumor cell development since tumor cells do not exist alone but in the tumor microenvironment. In the tumor microenvironment, tumor cells are interconnected with other stromal cells and influence each other, among which tumor-associated macrophages (TAMs) are the most numerous immune cells. At the same time, it was found that cancer cells have different levels of autophagy from normal cells. In cancer therapy, the occurrence of autophagy plays an important role in promoting tumor cell death or inhibiting tumor cell death, and is closely related to the environment. Therefore, elucidating the regulatory role of autophagy between TAMs and tumor cells may be an important breakthrough, providing new perspectives for further research on antitumor immune mechanisms and improving the efficacy of cancer immunotherapy.

Photorelaxation Pathways of 4-(N,N-Dimethylamino)-4'-nitrostilbene Upon S1 Excitation Revealed by Conical Intersection and Intersystem Crossing Networks.

Multi-state n-electron valence state second order perturbation theory (MS-NEVPT2) was utilized to reveal the photorelaxation pathways of 4-(N,N-dimethylamino)-4'-nitrostilbene (DANS) upon S1 excitation. Within the interwoven networks of five S1/S0 and three T2/T1 conical intersections (CIs), and three S1/T2, one S1/T1 and one S0/T1 intersystem crossings (ISCs), those competing nonadiabatic decay pathways play different roles in trans-to-cis and cis-to-trans processes, respectively. After being excited to the Franck-Condon (FC) region of the S1 state, trans-S1-FC firstly encounters an ultrafast conversion to quinoid form. Subsequently, the relaxation mainly proceeds along the triplet pathway, trans-S1-FC → ISC-S1/T2-trans → CI-T2/T1-trans → ISC-S0/T1-twist → trans- or cis-S0. The singlet relaxation pathway mediated by CI-S1/S0-twist-c is hindered by the prominent energy barrier on S1 surface and by the reason that CI-S1/S0-trans and CI-S1/S0-twist-t are both not energetically accessible upon S1 excitation. On the other hand, the cis-S1-FC lies at the top of steeply decreasing potential energy surfaces (PESs) towards the CI-S1/S0-twist-c and CI-S1/S0-DHP regions; therefore, the initial twisting directions of DN and DAP moieties determine the branching ratio between αC=C twisting (cis-S1-FC → CI-S1/S0-twist-c → trans- or cis-S0) and DHP formation relaxation pathways (cis-S1-FC → CI-S1/S0-DHP → DHP-S0) on the S1 surface. Moreover, the DHP formation could also take place via the triplet relaxation pathway, cis-S1-FC → ISC-S1/T1-cis → DHP-T1 → DHP-S0, however, which may be hindered by insufficient spin-orbit coupling (SOC) strength. The other triplet pathways for cis-S1-FC mediated by ISC-S1/T2-cis are negligible due to the energy or geometry incompatibility of possible consecutive stepwise S1 → T2 → T1 or S1 → T2 → S1 processes. The present study reveals photoisomerization dynamic pathways via conical intersection and intersystem crossing networks and provides nice physical insight into experimental investigation of DANS.

Quercetin Enhances 5-fluorouracil Sensitivity by Regulating the Autophagic Flux and Inducing Drp-1 Mediated Mitochondrial Fragmentation in Colorectal Cancer Cells.

BACKGROUND: While chemotherapy treatment demonstrates its initial effectiveness in eliminating the majority of the tumor cell population, nevertheless, most patients relapse and eventually succumb to the disease upon its recurrence. One promising approach is to explore novel, effective chemotherapeutic adjuvants to enhance the sensitivity of cancer cells to conventional chemotherapeutic agents. In the present study, we explored the effect of quercetin on the sensitivity of colorectal cancer (CRC) cells to conventional chemotherapeutic agent 5-fluorouracil (5-FU) and the molecular mechanisms. METHODS: MTT assay, colony formation assay and Hoechst staining were performed to investigate the growth inhibition effect of quercetin alone or combined with 5-FU. The expression levels of apoptosis- and autophagy-related proteins were assessed by western blotting. Intracellular ROS was detected using DCFH-DA. The change in the mitochondrial membrane potential was measured by a JC-1 probe. The effect of quercetin on mitochondrial morphology was examined using a mitochondrial-specific fluorescence probe, Mito-Tracker red. RESULTS: The results demonstrated quercetin-induced apoptosis and autophagy, as well as imbalanced ROS, decreased mitochondrial membrane potential, and Drp-1-mediated mitochondrial fission in CRC cells. Autophagy blockage with autophagy inhibitor chloroquine (CQ) enhanced quercetininduced cytotoxicity, indicating that quercetin-induced cytoprotective autophagy. Meanwhile, quercetin enhanced the sensitivity of CRC cells to 5- FU via the induction of mitochondrial fragmentation, which could be further enhanced when the quercetin-induced protective autophagy was blocked by CQ. CONCLUSION: Our findings suggested that quercetin could induce protective autophagy and Drp-1-mediated mitochondrial fragmentation and enhance the sensitivity of CRC cells to conventional agent 5-FU, which not only suggests that quercetin may act as a chemotherapeutic adjuvant but also implies that the regulation of autophagic flux may be a potential therapeutic strategy for colorectal cancer.