Tumor aerobic glycolysis, or the Warburg effect, plays important roles in tumor survival, growth, and metastasis. Pyruvate kinase isoenzyme M2 (PKM2) is a key enzyme that regulates aerobic glycolysis in tumor cells. Recent research has shown that PKM2 can be used as a tumor marker for diagnosis and, in particular, as a potential target for cancer therapy. We investigated the effects of combining shRNA targeting PKM2 and docetaxel on human A549 lung carcinoma cells both in vivo and in vitro. We observed that the shRNA can significantly downregulate the expression level of PKM2. The decrease of PKM2 resulted in a decrease in ATP synthesis, which caused intracellular accumulation of docetaxel. Furthermore, the combination of pshRNA-pkm2 and docetaxel inhibited tumor growth and promoted more cancer cell apoptosis both in vivo and in vitro. Our findings suggest that targeting tumor glycolysis can increase the efficacy of chemotherapy. In particular, the targeting of PKM2 could, to some extent, be a new way of reversing chemotherapy resistance to cancer therapy. (Cancer Sci 2010; 101: 1447-1453 T umor glycolysis is different from that in many normal adult organizations in metabolism; and the tumor glycolysis plays an important role in tumor energy metabolism.(1,2) Cancer cells take up glucose at higher rates than normal tissue but are prone to produce energy through glycolysis, rather than through mitochondrial oxidation of pyruvate, even when the supply of oxygen is not limited. This effect, called aerobic glycolysis or the Warburg effect, is very important to tumor growth. In addition to providing a rapid rate of ATP production, glycolysis increases lactate production resulting in an acidification of the extracellular milieu, which is believed to facilitate cell invasion and metastasis and bestow a resistance to chemotherapy.(3-5) A high level of glycolysis will also provide an increased supply of the precursors needed for the synthesis of nucleotides, proteins, and lipids in tumor cells. Cancer cells generally show signs of increased glycolysis for ATP generation, due in part to mitochondrial respiration injury and hypoxia, which are frequently associated with resistance to therapeutic agents. Increasing evidence has shown that inhibition of glycolysis signaling is a promising approach for cancer treatment. (3,(6)(7)(8)(9)(10) Previous studies have shown that glycolytic genes comprise some of the most unregulated genes in cancer. (11,12) Among them, pyruvate kinase (PK) plays a crucial role in regulating the ratelimiting final step of glycolysis, catalyzing the formation of pyruvate and ATP from phosphoenolpyruvate and ADP. (13,14) Four isoforms of PK have been found in mammals, designated L, R, M1, and M2. Each is differentially expressed in different cell types. (14) The pyruvate kinase M2 isoenzyme (PKM2) is expressed in several differentiated tissues, for example, lung, fat tissue, pancreatic islets, and especially tumor cells.(15-18) During multistep carcinogenesis, the first step is the loss of the tissue-sp...

Cancer-associated fibroblasts (CAFs) are common components of the tumor-suppressive microenvironment, and are a major determinant of the poor outcome of therapeutic vaccination. In this study, we modified tumor cells to express the fibroblast activation protein (FAP), which is highly expressed by CAFs, to potentially improve whole-cell tumor vaccines by targeting both tumor cells and CAFs. Tumor cells were transfected with murine FAP plasmids bearing the cationic lipid DOTAP. Its antitumor effects were investigated in three established tumor models. Vaccination with tumor cells expressing FAP eliminated solid tumors and tumors resulting from hematogenous dissemination. This antitumor immune response was mediated by CD8+ T cells. Additionally, we found that CAFs were significantly reduced within the tumors. Furthermore, this vaccine enhanced the infiltration of CD8+ T lymphocytes, and suppressed the accumulation of immunosuppressive cells in the tumor microenvironment. Our results indicated that the FAP-modified whole-cell tumor vaccine induced strong antitumor immunity against both tumor cells and CAFs and reversed the immunosuppressive effects of tumors by decreasing the recruitment of immunosuppressive cells and enhancing the recruitment of effector T cells. This conclusion may have important implications for the clinical use of genetically modified tumor cells as cancer vaccines.

BackgroundSUMO-activating enzyme subunit 2 (SAE2) is the sole E1-activating enzyme required for numerous important protein SUMOylation, abnormal of which is associated with carcinogenesis. SAE2 inactivation was recently reported to be a therapeutic strategy in cancers with Myc overexpression. However, the roles of SAE2 in small cell lung cancer (SCLC) are largely unknown.MethodsStably SAE2 knockdown in H446 cells were established with a lentiviral system. Cell viability, cell cycle, and apoptosis were analyzed using MTT assay and flow cytometric assay. Expression of SAE2 mRNA and protein were detected by qPCR, western blotting, and immunohistochemical staining. Cell invasion and migration assay were determined by transwell chamber assay. H446 cells with or without SAE2 knockdown, nude mice models were established to observe tumorigenesis.ResultsSAE2 was highly expressed in SCLC and significantly correlated with tumorigenesis in vivo. Cancer cells with RNAi-mediated reduction of SAE2 expression exhibited growth retardation and apoptosis increasing. Furthermore, down-regulation of SAE2 expression inhibited migration and invasion, simultaneously increased the sensitivity of H446 to etoposide and cisplatin.ConclusionsSAE2 plays an important role in tumor growth, metastasis, and chemotherapy sensitivity of H446 and is a potential clinical biomarker and therapeutic target in SCLC with high c-Myc expression.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-015-0164-y) contains supplementary material, which is available to authorized users.

No abstract

BackgroundNatural killer (NK) cells can kill tumor cells in a non-MHC-restricted manner. However, cancer cells frequently escape from the attack of NK cells by multiple ways. In this study, we investigated the effect of gefitinib on the interaction between NK cells and lung cancer cells.Methods51Cr release assay, CD107a assay, and IFN-γ secretion assay were performed to detect the sensitivity of lung cancer cell lines A549 and H1975 to NK cells cytotoxicity in the presence of gefitinib. Human NK cells were co-cultured with A549 and H1975 cell lines in the presence of gefitinib. NKG2D ligands, ULBP1, ULBP2, MICA, and MHC-I on tumor cells, and NKG2D, NKp44 and NKp46 on NK cells were evaluated with flow cytometry. 51Cr release assay was performed when NKG2D antibody were added into the co-culture system. Expressions of stat3 and LC3 I/II on tumor cells were determined with western blot after co-cultured with NK cells. After treated with gefitinib, mannose-6-phosphate receptor (MPR) on H1975 cells was evaluated by flow cytometry. 51Cr release assay were performed when MPR antagonist were used.ResultsGefitinib increased cytotoxicity of NK cells to human lung cancer H1975 cells with EGFR L858R + T790M mutations, while not in A549 cells with wild type EGFR. Gefitinib could block the immune escape by up-regulating the expression of NKG2D ligands ULBP1, ULBP2 or MICA on tumor cells and NKG2D on NK cells in the co-culture system. Gefitinib and NK cells up-regulated MHC-I expression in A549 while not in H1975 cells. NKG2D antibody blocked the enhanced NK cytotoxicity by gefitinib. The combination of NK cells and gefitinib could significantly down-regulate stat3 expression. Furthermore, NK cells-mediated tumor cell autophagy was observed in A549 cells while not in H1975 cells. Notably, gefitinib increased autophagy and MPR expression in H1975 cells, which improved the sensitivity to NK cell-based immunotherapy.ConclusionsGefitinib greatly enhanced NK cell cytotoxicity to lung cancer cells with EGFR L858R + T790M resistance mutation. Combination of EGFR tyrokinase inhibitors and NK cells adoptive immunotherapy may represent a potentially effective strategy for patients with non-small cell lung cancer.

Neuropsychological factors have been shown to influence tumor progression and therapeutic response. The present study investigated the effect of the dopamine receptor antagonist thioridazine on murine breast cancer. The anti-tumor efficacy of thioridazine was assessed using a murine breast cancer model. Cell apoptosis and proliferation were analyzed in vitro using flow cytometry (FCM) and the MTT assay, respectively. Western blot analysis was performed to assess Akt, phosphorylated (p)-Akt, signal transducer and activator of transcription (STAT) 3, p-STAT3 and p-p65 in tumor cells following treatment with thioridazine. The Ki67 index and the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells were assessed in the tumor sections. Thioridazine was found to reduce tumor growth, inhibit tumor cell proliferation and induce apoptosis in a dose- and time-dependent manner in vitro. Thioridazine was also found to markedly inhibit tumor proliferation and induce tumor cell apoptosis in vivo as shown by the lower Ki67 index and increase in TUNEL-positive cells. In addition, thioridazine was observed to inhibit the activation of the canonical nuclear factor κ-light-chain-enhancer of activated B cells pathway and exert anti-tumor effects by remodeling the tumor stroma, as well as inhibit angiogenesis in the tumor microenvironment. In conclusion, thioridazine was found to significantly inhibit breast tumor growth and the potential for thioridazine to be used in cancer therapy may be re-evaluated and investigated in clinical settings.

First-generation epidermal growth factor receptor (EGFR) targeted kinase inhibitors (TKIs) are still used in selected non-small cell lung cancer (NSCLC) patients despite the resistance. Based on the correlation of programmed cell death receptor ligand 1 (PD-L1) and EGFR signaling pathway, whether continuous TKIs treatment will affect PD-L1 expression after disease progression remains unclear. To investigate the potential change of PD-L1 expression in TKI-resistant NSCLC after continuous TKIs treatment, we treated H1975 and HCC827 for more than one month and explored the possible effect on immune cells as well as underlying biological mechanisms. We found that continuous exposure to TKIs induced upregulation of PD-L1 in H1975 and HCC827. Moreover, PD-L1 upregulation significantly inhibited proliferation and slightly promoted apoptosis of T cells. We observed the activation of STAT3 and ERK1/2 along with the PD-L1 upregulation. With the pathway inhibitors, we found ERK1/2 pathway involved in inducing PD-L1 in resistant lung cancer. This study provides preclinical evidence that continuous TKIs treatment may induce PD-L1 expression in resistant NSCLC, resulting in the suppression of T cell function and immune escape. ERK1/2 pathway inhibitors, PD-L1/PD-1 inhibitors or combination strategies should be considered to reverse the resistance to TKIs in NSCLC patients.

Hemorrhage is a common clinical manifestation in patients with cancer. Intratumor hemorrhage has been demonstrated to be a poor prognostic factor for cancer patients. In this study, we investigated the role of RBCs and hemoglobin (Hb) in the process of tumor progression and therapeutical response. RBCs and Hb potently promoted tumor cell proliferation and syngenic tumor growth. RBCs and Hb activated the reactive oxygen species–NF-κB pathway in both tumor cells and macrophages. RBCs and Hb also induced chemoresistance mediated, in part, by upregulating ABCB1 gene expression. Tumor growth induced by RBCs was accompanied by an inflammatory signature, increased tumor vasculature, and influx of M2 macrophages. In both the peritoneal cavity and tumor microenvironment, extravascular RBCs rapidly recruited monocyte–macrophages into the lesion sites. In addition, RBCs and Hb increased several nucleotide-binding oligomerization domain–like receptors' expression and induced IL-1β release. Our results provide novel insights into the protumor function of RBCs and Hb as endogenous danger signals, which can promote tumor cell proliferation, macrophage recruitment, and polarization. Hemorrhage may represent a useful prognostic factor for cancer patients because of its role in tumor promotion and chemoresistance.