Mutant p53 (R248Q) induces doxorubicin (ADM) resistance in hepatocellular carcinoma (HCC). Dihydroartemisinin (DHA) can synergistically enhance anticancer effect of many chemotherapeutic agents. However, whether DHA could increase therapeutic efficacy of ADM in p53 (R248Q)-expressing HCC cells remains unknown. In the present study, we established mutant p53 (R248Q)-expressing Hep3B cells to study the effect and mechanism of DHA on ADM resistance and the synergistic effect of DHA with ADM. We found that P-gp was highly expressed in p53 (R248Q)-expressing Hep3B cells. As a result, cells expressing p53 (R248Q) displayed higher cell viability and lower cell apoptosis level upon ADM treatment. Meanwhile, phosphorylation levels of ERK1/2 and p65 were elevated in p53 (R248Q)-expressing Hep3B cells. However, combination of DHA and ADM treatment decreased cell viability and elevated cell apoptosis level in p53 (R248Q)-expressing Hep3B cells. Molecular dynamics simulations showed that DHA had the potential to bind with mutant p53 (R248Q) protein. Furthermore, DHA treatment decreased P-gp expression and inhibited phosphorylation levels of ERK1/2 and p65 in p53 (R248Q)-expressing Hep3B cells. Finally, DHA treatment could significantly reduce ADM efflux in p53 (R248Q)-expressing cells. Our results indicate that DHA could decrease P-gp expression via inhibiting the p53 (R248Q)-ERK1/2-NF-κB signaling pathway, which eventually confers sensitization of p53 (R248Q)-expressing HCC cells to ADM. Our study provides evidence for the potential application of DHA and ADM combination in treatment of mutant p53 (R248Q)-harbored HCC.

Mutation or loss of the tumor suppressor gene PTEN or its functional status in tumor stromal cells may affect tumor occurrence, development, invasion, and metastasis, in which, however, the role of overall low PTEN expression, mutation, or deletion in the tumor-bearing host has rarely been reported. Breast cancer is a common highly invasive metastatic tumor. We therefore treated mouse breast cancer 4T1 cells with the specific PTEN inhibitor VO-OHpic to study the effects of PTEN suppression or deletion on malignant behavior in vivo and in vitro. VO-OHpic effectively inhibited PTEN gene/protein expression in 4T1 cells, accelerated cell proliferation, and enhanced cell migration and invasion. We also transplanted 4T1 cells with VO-OHpic-inhibited PTEN into mice to create orthotopic and metastatic breast cancer models. The proliferation of 4T1 cells in mouse mammary gland was increased and distant metastasis was enhanced, with metastatic foci in the lung, liver, and intestinal tract. In addition, injection of mice with VO-OHpic to inhibit PTEN in the overall microenvironment accelerated the proliferation of transplanted 4T1 cells and enhanced distant metastasis and the formation of metastatic tumors. Metastatic foci formed in the lung, liver, intestine, thymus, and brain, and PTEN levels in the organ/tissues were negatively associated with the formation of metastatic foci. Similarly, inoculation of PTEN-deficient 4T1 cells into systemic PTEN-inhibited mice further enhanced the orthotopic growth and distant metastasis of 4T1 breast cancer. VO-OHpic inhibition of PTEN in 4T1 cells was also associated with significantly increased phosphorylation of Akt and phosphoinositide 3-kinase (PI3K), suggesting that inhibition of PTEN could activate the PI3K-Akt pathway, as a key signaling pathway regulating cell proliferation and death. These results confirmed that functional loss or deletion of the tumor suppressor gene PTEN significantly enhanced the proliferation, invasion, and metastasis of 4T1 cells. Systemic decrease or deletion of PTEN in the organism or organ/tissue microenvironment was conducive to the proliferation of breast cancer cells in situ and distant metastasis. These results suggest that, as well the PTEN in cancer cells the systemic microenvironment PTEN intensely mediates the proliferation, invasion and metastasis of mouse breast cancer cells via regulating the PI3K-Akt signaling pathway.

Tumor-infiltrating lymphocytes (TILs) are vital elements of the tumor microenvironment (TME), and the anti-tumor activity of TILs on colorectal cancer (CRC) has been a topic of concern. However, the characteristics and prognosis of the various types of lymphocyte infiltration in CRC have not been fully explained. Our study aimed to identify distinct features and prognosis of TILs. We integrated multiple-cohort databases to illustrate the features, proportions, and prognosis of TILs on CRC. We found that macrophages were significantly enriched in CRC. When we used the scRNA-seq database to further evaluate the proportion of TILs, we noticed markedly higher numbers of CD4 + T cell, B cell, and CD8 + T cell in four Gene Expression Omnibus Series (GSE) CRC cohorts. Interestingly, we found that the infiltrating level of TIL subgroups from highest to lowest is always dendritic cells, CD8 + T cells, CD4 + T cells, neutrophils, B cells, and macrophages; the proportion of infiltration is largely constant regardless of mutations in specific genes or somatic copy number variation (sCNV). In addition, the data corroborated that CD4+ TILs and CD8+ TILs have certain application values in the prognosis of CRCs, and age negatively related to CD8+ TILs and B plasma infiltration. Finally, patients with CRC who are older than 70 years have a better response to immune-checkpoint blockade. Graphic Abstract

The molecular mechanisms and role of ferroptosis in tumor drug resistance remain unclear. In this study, we found that multidrug-resistant (MDR) K562/adriamycin (ADM) leukemia cells possessed higher glutathione (GSH) levels and iron-regulatory protein 2 (IRP2), transferrin receptor, ferritin heavy chain 1 (FTH1), and peroxidase-4 (GPX4) expression than parental drug-sensitive K562 leukemia cells. These elevations might have increased the antioxidant ability of K562/ADM cells and granted them increased buffering capacity against iron disorder, protecting them from ferroptosis and favoring drug resistance. However, dihydroartemisinin (DHA) restrained MDR K562/ADM cell viability and enhanced the sensitivity to ADM by strengthening ferroptosis induced by downregulation of GSH levels and GPX4, IRP2, and FTH expression, upregulation of reactive oxygen species (ROS) levels, and the consequent suppression of total serine/threonine kinase (AKT), total mammalian target of rapamycin (t-mTOR), phosphorylated mTOR (p-mTOR), and p-mTOR/t-mTOR levels. Moreover, compared with K562 cells, MDR K562/ADM cells exhibited greater ROS increases, GSH decreases, and viability rescue after ferroptosis inhibitor treatment owing to further suppression of FTH1, GPX4, p-mTOR, and p-mTOR/t-mTOR. Collectively, the increase in oxidative damage and the blockade of antioxidant defence shaped DHA-induced ferroptosis, which was responsible for the sensitivity of MDR leukemia cells to DHA. Regulating iron homeostasis/ROS/AKT/mTOR might be a potential chemotherapeutic strategy for sensitizing drug-resistant leukemia.

Gastric cancer (GC) is the 5^th most prevalent cancer and the 4^th primary cancer-associated mortality globally. As the first identified m6A demethylase for removing RNA methylation modification, fat mass and obesity-associated protein (FTO) plays instrumental roles in cancer development. Therefore, we study the biological functions and oncogenic mechanisms of FTO in GC tumorigenesis and progression. In our study, FTO expression is obviously upregulated in GC tissues and cells. The upregulation of FTO is associated with advanced nerve invasion, tumor size, and LNM, as well as the poor prognosis in GC patients, and promoted GC cell viability, colony formation, migration and invasion. Mechanistically, FTO targeted specificity protein 1 and Aurora Kinase B, resulting in the phosphorylation of ataxia telangiectasia mutated and P38 and dephosphorylation of P53. In conclusion, the m6A demethylase FTO promotes GC tumorigenesis and progression by regulating the SP1-AURKB-ATM pathway, which may highlight the potential of FTO as a diagnostic biomarker for GC patients’ therapy response and prognosis.