Predictive DNA damage signaling for low­dose ionizing radiation.

Numerous studies have attempted to develop biological markers for the response to radiation for broad and straightforward application in the field of radiation. Based on a public database, the present study selected several molecules involved in the DNA damage repair response, cell cycle regulation and cytokine signaling as promising candidates for low­dose radiation­sensitive markers. The HuT 78 and IM­9 cell lines were irradiated in a concentration­dependent manner, and the expression of these molecules was analyzed using western blot analysis. Notably, the activation of ataxia telangiectasia mutated (ATM), checkpoint kinase 2 (CHK2), p53 and H2A histone family member X (H2AX) significantly increased in a concentration­dependent manner, which was also observed in human peripheral blood mononuclear cells. To determine the radioprotective effects of cinobufagin, as an ATM and CHK2 activator, an in vivo model was employed using sub­lethal and lethal doses in irradiated mice. Treatment with cinobufagin increased the number of bone marrow cells in sub­lethal irradiated mice, and slightly elongated the survival of lethally irradiated mice, although the difference was not statistically significant. Therefore, KU60019, BML­277, pifithrin­α, and nutlin­3a were evaluated for their ability to modulate radiation­induced cell death. The use of BML­277 led to a decrease in radiation­induced p­CHK2 and γH2AX levels and mitigated radiation­induced apoptosis. On the whole, the present study provides a novel approach for developing drug candidates based on the profiling of biological radiation­sensitive markers. These markers hold promise for predicting radiation exposure and assessing the associated human risk.

Ionizing Radiation-treated NRF2-deficient Cancer Cells Promote Type I Interferon Signaling in Immune Cells.

BACKGROUND/AIM: Nuclear factor erythroid-derived 2-related factor-2 (NRF2) is a transcription factor that regulates stress response genes. It negatively regulates the immune system by acting as a transcriptional repressor of inflammatory genes or suppressing type I interferon (IFN) production pathways. NRF2 is often over-expressed in some tumors, including non-small cell lung cancer, and modulates these tumors via an immune-cold microenvironment. Thus, strategies to convert cold tumors into hot tumors are effective for cancer treatment. MATERIALS AND METHODS: NRF2 was knocked-down or over-expressed in human cancer cells (A549, HeLa, H1299, H1650) and mouse mammary adenocarcinoma TS/A cells. Cells were irradiated or transfected with poly(I:C), and changes in type I IFN levels were examined using quantitative real-time polymerase chain reaction and western blotting. Cytosolic DNA was assayed via PicoGreen staining and immune and cancer cells were co-cultured. RESULTS: Regulation of NRF2 expression altered type I IFN levels in the human lung cancer cell line A549 and several solid tumors. Down-regulation of NRF2 resulted in increased levels of cytosolic DNA and activated the cGAS-STING pathway. We confirmed that type I IFN was induced in NRF2-down-regulated tumor cells using ionizing radiation (IR). Furthermore, when dendritic cells and macrophages were co-cultured with IR-exposed NRF2 knockdown tumor cells, the immune cells produced more IFNB1 and CXCL10. CONCLUSION: The immunosuppressive tumor cell environment is improved by NRF2 down-regulation, and IR treatment may promote immune cell signaling activation.

Poliovirus receptor inhibition in breast cancer cells induces antitumor immunity via T cell activation.

Radiotherapy (RT) is a commonly used treatment option for patients with cancer because it can effectively control tumor growth and kill tumor cells. However, the impact of RT goes beyond direct tumor cell killing because it can change the tumor microenvironment by altering surrounding tissues and infiltrating cells and modulating the expression of immune checkpoints. Poliovirus receptor (PVR, cluster of differentiation (CD)155), a member of the nectin-like molecule family, is overexpressed in many human cancers. However, its role in the tumor growth and T-cell immune responses of triple-negative breast cancer (TNBC) remains unclear. In the present study, we observe that radiation exposure increases PVR expression in MDA-MB-231 and BT549 cells. Silencing PVR not only inhibited the proliferation of breast cancer cells but also significantly enhanced the cytotoxicity of cytotoxic T lymphocytes (CTLs) compared with the control or RT groups. Treatment of T cells with PVR decreased CD8+ T cells, increased CD4+ T cells, and induced PVR ligands such as T cell immunoreceptor with immunoglobulin and ITIM domain, CD226, and CD96. However, after treatment with PVR, CTL responses decreased and secretion of interferon-γ, tumor necrosis factor-α, interleukin (IL)-2, IL-6, and IL-10 was significantly inhibited. In contrast, PVR knockdown increased the production of these cytokines, illustrating the immunosuppressive function of PVR. Suppression of PVR using an anti-PVR antibody inhibited 4T1 tumor growth by increasing immune cell infiltration. These results provide new insights into the role of PVR in TNBC and highlight its potential as a target for T cell-mediated immunotherapy in breast cancer.

JNC-1043, a Novel Podophyllotoxin Derivative, Exerts Anticancer Drug and Radiosensitizer Effects in Colorectal Cancer Cells.

The objective of this study was to determine whether (5S)-5-(4-benzyloxy-3,5-dimethoxy-phenyl)-5,9-dihydro-8H-furo [3',4':6,7] naphtho [2,3-d] [1,3]dioxol-6-one (JNC-1043), which is a novel chemical derivative of ß-apopicropodophyllin, acts as a novel potential anticancer reagent and radiosensitizer in colorectal cancer (CRC) cells. Firstly, we used MTT assays to assess whether JNC-1043 could inhibit the cell proliferation of HCT116 and DLD-1 cells. The IC50 values of these cell lines were calculated as 114.5 and 157 nM, respectively, at 72 h of treatment. Using doses approximating the IC50 values, we tested whether JNC-1043 had a radiosensitizing effect in the CRC cell lines. Clonogenic assays revealed that the dose-enhancement ratios (DER) of HCT116 and DLD-1 cells were 1.53 and 1.25, respectively. Cell-counting assays showed that the combination of JNC-1043 and γ-ionizing radiation (IR) enhanced cell death. Treatment with JNC-1043 or IR alone induced cell death by 50~60%, whereas the combination of JNC-1043 and IR increased this cell death by more than 20~30%. Annexin V-propidium iodide assays showed that the combination of JNC-1043 and IR increased apoptosis by more 30~40% compared to that induced by JNC-1043 or IR alone. DCFDA- and MitoSOX-based assays revealed that mitochondrial ROS production was enhanced by the combination of JNC-1043 and IR. Finally, we found that suppression of ROS by N-acetylcysteine (NAC) blocked the apoptotic cell death induced by the combination of JNC-1043 and IR. The xenograft model also indicated that the combination of JNC-1043 and IR increased apoptotic cell death in tumor mass. These results collectively suggest that JNC-1043 acts as a radiosensitizer and exerts anticancer effects against CRC cells by promoting apoptosis mediated by mitochondrial ROS.

Receptor interacting protein 1 knockdown induces cell death in liver cancer by suppressing STAT3/ATR activation in a p53-dependent manner.

The survival and death of eukaryotic cells are tightly controlled by a variety of proteins in response to the cellular environment. Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) is a receptor-interacting Ser/Thr kinase that has recently been reported as an important regulator of cell survival, apoptosis, and necroptosis; however, its role in liver cancer remains unclear. In this study, we examined the effect of siRNA-mediated RIPK1 knockdown on the survival and death of liver cancer cells. Treatment with siRIPK1 decreased the growth rate of liver cancer cells and increased apoptotic, but not necrotic cell death, which was higher in wild-type p53 (wt-p53) cells than in mutant-type p53 (mt-p53) cells. In addition, RIPK1 knockdown increased p53 expression and G1 phase arrest in wt-p53 cells. Although suppressing p53 did not alter RIPK1 expression, it did attenuate siRIPK1-induced cell death. Interestingly, RIPK1 knockdown also increased the generation of reactive oxygen species and DNA damage by inhibiting signal transduced and activator of transcription 3 (STAT3) and ATM and RAD3-related (ATR) in wt-p53 cells but not in mt-p53 cells. Moreover, STAT3 or ATR inhibition in p53 mutant cells restored siRIPK1-mediated cell death. Together, the results of this study suggest that RIPK1 suppression induces apoptotic cell death by inhibiting the STAT3/ATR axis in a p53-dependent manner. Furthermore, these findings suggest that RIPK1, alone or in combination, may be a promising target for treating liver cancer.

BHMPS Inhibits Breast Cancer Migration and Invasion by Disrupting Rab27a-Mediated EGFR and Fibronectin Secretion.

Our previous work demonstrated that (E)-N-benzyl-6-(2-(3, 4-dihydroxybenzylidene) hydrazinyl)-N-methylpyridine-3-sulfonamide (BHMPS), a novel synthetic inhibitor of Rab27aSlp(s) interaction, suppresses tumor cell invasion and metastasis. Here, we aimed to further investigate the mechanisms of action and biological significance of BHMPS. BHMPS decreased the expression of epithelial-mesenchymal transition transcription factors through inhibition of focal adhesion kinase and c-Jun N-terminal kinase activation, thereby reducing the migration and invasion of breast cancer. Additionally, knockdown of Rab27a inhibited tumor migration, with changes in related signaling molecules, whereas overexpression of Rab27a reversed this phenomenon. BHMPS effectively prevented the interaction of Rab27a and its effector Slp4, which was verified by co-localization, immunoprecipitation, and in situ proximity ligation assays. BHMPS decreased the secretion of epidermal growth factor receptor and fibronectin by interfering with vesicle trafficking, as indicated by increased perinuclear accumulation of CD63-positive vesicles. Moreover, administration of BHMPS suppressed tumor growth in Rab27a-overexpressing MDA-MB-231 xenograft mice. These findings suggest that BHMPS may be a promising candidate for attenuating tumor migration and invasion by blocking Rab27a-mediated exocytosis.

A novel function of HRP-3 in regulating cell cycle progression via the HDAC-E2F1-Cyclin E pathway in lung cancer.

To improve the poor survival rate of lung cancer patients, we investigated the role of HDGF-related protein 3 (HRP-3) as a potential biomarker for lung cancer. The expression of endogenous HRP-3 in human lung cancer tissues and xenograft tumor models is indicative of its clinical relevance in lung cancer. Additionally, we demonstrated that HRP-3 directly binds to the E2F1 promoter on chromatin. Interestingly, HRP-3 depletion in A549 cells impedes the binding of HRP-3 to the E2F1 promoter; this in turn hampers the interaction between Histone H3/H4 and HDAC1/2 on the E2F1 promoter, while concomitantly inducing Histone H3/H4 acetylation around the E2F1 promoter. The enhanced Histone H3/H4 acetylation on the E2F1 promoter through HRP-3 depletion increases the transcription level of E2F1. Furthermore, the increased E2F1 transcription levels lead to the enhanced transcription of Cyclin E, known as the E2F1-responsive gene, thus inducing S-phase accumulation. Therefore, our study provides evidence for the utility of HRP-3 as a biomarker for the prognosis and treatment of lung cancer. Furthermore, we delineated the capacity of HRP-3 to regulate the E2F1 transcription level via histone deacetylation.

Radiosensitizer Effect of ß-Apopicropodophyllin against Colorectal Cancer via Induction of Reactive Oxygen Species and Apoptosis.

ß-apopicropodophyllin (APP), a derivative of podophyllotoxin (PPT), has been identified as a potential anti-cancer drug. This study tested whether APP acts as an anti-cancer drug and can sensitize colorectal cancer (CRC) cells to radiation treatment. APP exerted an anti-cancer effect against the CRC cell lines HCT116, DLD-1, SW480, and COLO320DM, with IC50 values of 7.88 nM, 8.22 nM, 9.84 nM, and 7.757 nM, respectively, for the induction of DNA damage. Clonogenic and cell counting assays indicated that the combined treatment of APP and γ-ionizing radiation (IR) showed greater retardation of cell growth than either treatment alone, suggesting that APP sensitized CRC cells to IR. Annexin V-propidium iodide (PI) assays and immunoblot analysis showed that the combined treatment of APP and IR increased apoptosis in CRC cells compared with either APP or IR alone. Results obtained from the xenograft experiments also indicated that the combination of APP and IR enhanced apoptosis in the in vivo animal model. Apoptosis induction by the combined treatment of APP and IR resulted from reactive oxygen species (ROS). Inhibition of ROS by N-acetylcysteine (NAC) restored cell viability and decreased the induction of apoptosis by APP and IR in CRC cells. Taken together, these results indicate that a combined treatment of APP and IR might promote apoptosis by inducing ROS in CRC cells.

Discovery of a Novel Triazolopyridine Derivative as a Tankyrase Inhibitor.

More than 80% of colorectal cancer patients have adenomatous polyposis coli (APC) mutations, which induce abnormal WNT/ß-catenin activation. Tankyrase (TNKS) mediates the release of active ß-catenin, which occurs regardless of the ligand that translocates into the nucleus by AXIN degradation via the ubiquitin-proteasome pathway. Therefore, TNKS inhibition has emerged as an attractive strategy for cancer therapy. In this study, we identified pyridine derivatives by evaluating in vitro TNKS enzyme activity and investigated N-([1,2,4]triazolo[4,3-a]pyridin-3-yl)-1-(2-cyanophenyl)piperidine-4-carboxamide (TI-12403) as a novel TNKS inhibitor. TI-12403 stabilized AXIN2, reduced active ß-catenin, and downregulated ß-catenin target genes in COLO320DM and DLD-1 cells. The antitumor activities of TI-12403 were confirmed by the viability of the colorectal cancer cells and its lack of visible toxicity in DLD-1 xenograft mouse model. In addition, combined 5-FU and TI-12403 treatment synergistically inhibited proliferation to a greater extent than that in a single drug treatment. Our observations suggest that TI-12403, a novel selective TNKS1 inhibitor, may be a suitable compound for anticancer drug development.

Anti-leukemic Activity of AIU2008 in FLT3-ITD-positive Acute Myeloid Leukemia.

BACKGROUND/AIM: FMS-like tyrosine kinase 3 (FLT3) is a class III receptor tyrosine kinase involved in signal transduction underlying survival, proliferation, and differentiation of hematopoietic cells. An internal tandem duplication (ITD) in FLT3 in the juxtamembrane domain is a common mutation causing human acute myeloid leukemia (AML) and activates constitutive signaling. MATERIALS AND METHODS: We evaluated the novel FLT3 inhibitor 5-(4-fluorophenyl)-N-(naphthalen-1-yl)oxazol-2-amine (AIU2008) for the treatment of AML. RESULTS: AIU2008 was designed by modifying FLT3 inhibitor 7c, and showed improved anti-leukemic efficacy in FLT3-ITD-positive AML cells. Specifically, AIU2008 inhibited cell growth and apoptotic death. In addition, AIU2008 down-regulated DNA repair genes involved in homologous recombination and non-homologous end joining. It contributed to the synergistic inhibition of AML cell growth in combination treatment with PARP inhibitors. CONCLUSION: AIU2008 is a promising FLT3 targeting agent, and may be used in combination with PARP inhibitors for the treatment of AML.

Radiation-induced IL-1ß expression and secretion promote cancer cell migration/invasion via activation of the NF-κB-RIP1 pathway.

Here, we demonstrate that interleukin-1ß (IL-1ß) contributes to the γ-ionizing radiation (IR)-induced increase of migration/invasion in A549 lung cancer cells, and that this occurs via RIP1 upregulation. We initially observed that the protein expression and secreted concentration of IL-1ß were increased upon exposure of A549 cells to IR. We then demonstrated that IR-induced IL-1ß is located downstream of the NF-κB-RIP1 signaling pathway. Treatments with siRNA and specific pharmaceutical inhibitors of RIP1 and NF-κB suppressed the IR-induced increases in the protein expression and secreted concentration of IL-1ß. IL-1Ra, an antagonist of IL-1ß, treatment suppressed the IR-induced epithelial-mesenchymal transition (EMT) and IR-induced invasion/migration in vitro. These results suggest that IL-1ß could regulate IR-induced EMT. We also found that IR could induce the expression of IL-1ß expression in vivo and that of IL-1 receptor (R) I/II in vitro and in vivo. The IR-induced increases in the protein levels of IL-1 RI/II and IL-1ß suggest that an autocrine loop between IL-1ß and IL-1 RI/II might play important roles in IR-induced EMT and migration/invasion. Based on these collective results, we propose that IR concomitantly activates NF-κB and RIP1 to trigger the NF-κB-RIP1-IL-1ß-IL-1RI/II-EMT pathway, ultimately promoting metastasis.

Discovery of Oxazol-2-amine Derivatives as Potent Novel FLT3 Inhibitors.

Internal tandem duplication (ITD) of FMS-like tyrosine kinase 3 (FLT3) is the most common mutation in patients with acute myeloid leukemia (AML). FLT3-ITD+ induces constitutive activation of FLT3, causing an abnormally rapid proliferation of cancer cells. In this study, we identified novel FLT3 inhibitors and investigated 5-(4-fluorophenyl)-N-phenyloxazol-2-amine (compound 7; 7c) as candidates for the treatment of AML. The results showed that 7c inhibited the activities of FLT3 and mutated FLT3 in a cell-free kinase assay and Molm-13 and MV4-11 cells, as well as the proliferation of FLT3-ITD+ AML cells, increasing apoptosis. The anti-leukemic activity of 7c was confirmed by in vivo tumor growth inhibition in MV4-11 xenograft mice. Besides, 7c suppressed the expression of DNA damage repair genes. Combination treatment with 7c and olaparib (a poly (ADP-ribose) polymerase [PARP] inhibitor) synergistically inhibited cell proliferation in Molm-13 and MV4-11 cells. Our findings demonstrated that 7c is a therapeutic candidate targeting FLT3 for AML treatment and suggested that combination treatment with 7c and a PARP inhibitor may be an effective therapy regimen for FLT3-mutated AML.

MKI-1, a Novel Small-Molecule Inhibitor of MASTL, Exerts Antitumor and Radiosensitizer Activities Through PP2A Activation in Breast Cancer.

Although MASTL (microtubule-associated serine/threonine kinase-like) is an attractive target for anticancer treatment, MASTL inhibitors with antitumor activity have not yet been reported. In this study, we have presented a novel MASTL inhibitor, MKI-1, identified through in silico screening and in vitro analysis. Our data revealed that MKI-1 exerted antitumor and radiosensitizer activities in in vitro and in vivo models of breast cancer. The mechanism of action of MKI-1 occurred through an increase in PP2A activity, which subsequently decreased the c-Myc protein content in breast cancer cells. Moreover, the activity of MKI-1 in the regulation of MASTL-PP2A was validated in a mouse oocyte model. Our results have demonstrated a new small-molecule inhibitor of MASTL, MKI-1, which exerts antitumor and radiosensitizer activities through PP2A activation in breast cancer in vitro and in vivo.

Gene expression profiling of glioblastoma cell lines depending on TP53 status after tumor-treating fields (TTFields) treatment.

Glioblastoma is frequently associated with TP53 mutation, which is linked to a worse prognosis and response to conventional treatments (chemoradiotherapy). Therefore, targeting TP53 is a promising strategy to overcome this poor therapeutic response. Tumor-treating fields (TTFields) are a recently approved treatment for newly diagnosed glioblastoma, which involves direct application of low-intensity, intermediate-frequency alternating electric fields to the tumor, thereby offering a local tumor-killing effect. However, the influence of TP53 mutation status on the effectiveness of TTFields is controversial. Here, we identified the key gene signatures and pathways associated with TTFields in four glioblastoma cell lines varying in TP53 mutation status using gene profiling and functional annotation. Overall, genes associated with the cell cycle, cell death, and immune response were significantly altered by TTFields regardless of TP53 status. TTFields appeared to exert enhanced anti-cancer effects by altering the immune system in the inflammatory environment and regulating cell cycle- and cell death-related genes, but the precise genes influenced vary according to TP53 status. These results should facilitate detailed mechanistic studies on the molecular basis of TTFields to further develop this modality as combination therapy, which can improve the therapeutic effect and minimize side effects of chemoradiotherapy.

RIP1 Is a Novel Component of γ-ionizing Radiation-Induced Invasion of Non-Small Cell Lung Cancer Cells.

Abstract: Previously, we demonstrated that γ-ionizing radiation (IR) triggers the invasion/migration of A549 cells via activation of an EGFR-p38/ERK-STAT3/CREB-1-EMT pathway. Here, we have demonstrated the involvement of a novel intracellular signaling mechanism in γ-ionizing radiation (IR)-induced migration/invasion. Expression of receptor-interacting protein (RIP) 1 was initially increased upon exposure of A549, a non-small cell lung cancer (NSCLC) cell line, to IR. IR-induced RIP1 is located downstream of EGFR and involved in the expression/activity of matrix metalloproteases (MMP-2 and MMP-9) and vimentin, suggesting a role in epithelial-mesenchymal transition (EMT). Our experiments showed that IR-induced RIP1 sequentially induces Src-STAT3-EMT to promote invasion/migration. Inhibition of RIP1 kinase activity and expression blocked induction of EMT by IR and suppressed the levels and activities of MMP-2, MMP-9 and vimentin. IR-induced RIP1 activation was additionally associated with stimulation of the transcriptional factor NF-κB. Specifically, exposure to IR triggered NF-κB activation and inhibition of NF-κB suppressed IR-induced RIP1 expression, followed by a decrease in invasion/migration as well as EMT. Based on the collective results, we propose that IR concomitantly activates EGFR and NF-κB and subsequently triggers the RIP1-Src/STAT3-EMT pathway, ultimately promoting metastasis.

Evaluation of Anti-Tumor Effects of Whole-Body Low-Dose Irradiation in Metastatic Mouse Models.

Low-dose irradiation (LDI) has recently been shown to have various beneficial effects on human health, such as on cellular metabolic activities, DNA repair, antioxidant activity, homeostasis potency, and immune activation. Although studies on the immunogenic effects of LDI are rapidly accumulating, clinical trials for cancer treatment are considered premature owing to the lack of available preclinical results and protocols. Here, we aim to investigate anti-tumor and anti-metastatic effects of whole-body LDI in several tumor-bearing mouse models. Mice were exposed to single or fractionated whole-body LDI prior to tumor transplantation, and tumor growth and metastatic potential were determined, along with analysis of immune cell populations and expression of epithelial-mesenchymal transition (EMT) markers. Whole-body fractionated-LDI decreased tumor development and lung metastasis not only by infiltration of CD4+, CD8+ T-cells, and dendritic cells (DCs) but also by attenuating EMT. Moreover, a combination of whole-body LDI with localized high-dose radiation therapy reduced the non-irradiated abscopal tumor growth and increased infiltration of effector T cells and DCs. Therefore, whole-body LDI in combination with high-dose radiation therapy could be a potential therapeutic strategy for treating cancer.

Kinesin light chain 4 as a new target for lung cancer chemoresistance via targeted inhibition of checkpoint kinases in the DNA repair network.

The poor therapeutic efficacy of non-small cell lung cancer (NSCLC) is partly attributed to the acquisition of chemoresistance. To investigate the mechanism underlying this resistance, we examined the potential link between kinesin light chain 4 (KLC4), which we have previously reported to be associated with radioresistance in NSCLC, and sensitivity to chemotherapy in human lung cancer cell lines. KLC4 protein levels in lung cancer cells correlated with the degree of chemoresistance to cisplatin treatment. Furthermore, KLC4 silencing enhanced the cytotoxic effect of cisplatin by promoting DNA double-strand breaks and apoptosis. These effects were mediated by interaction with the checkpoint kinase CHK2, as KLC4 knockdown increased CHK2 activation, which was further enhanced in combination with cisplatin treatment. In addition, KLC4 and CHEK2 expression levels showed negative correlation in lung tumor samples from patients, and KLC4 overexpression correlated negatively with survival. Our results indicate a novel link between the KLC4 and CHK2 pathways regulating DNA damage response in chemoresistance, and highlight KLC4 as a candidate for developing lung cancer-specific drugs and customized targeted molecular therapy.

A new FGFR inhibitor disrupts the TGF-ß1-induced fibrotic process.

Pulmonary fibrosis (PF) is chronic and irreversible damage to the lung characterized by fibroblast activation and matrix deposition. Although recently approved novel anti-fibrotic agents can improve the lung function and survival of patients with PF, the overall outcomes remain poor. In this study, a novel imidazopurine compound, 3-(2-chloro-6-fluorobenzyl)-1,6,7-trimethyl-1H-imidazo[2,1-f]purine-2,4(3H,8H)-dione (IM-1918), markedly inhibited transforming growth factor (TGF)-ß-stimulated reporter activity and reduced the expression of representative fibrotic markers, such as connective tissue growth factor, fibronectin, collagen and α-smooth muscle actin, on human lung fibroblasts. However, IM-1918 neither decreased Smad-2 and Smad-3 nor affected p38MAPK and JNK. Instead, IM-1918 reduced Akt and extracellular signal-regulated kinase 1/2 phosphorylation increased by TGF-ß. Additionally, IM-1918 inhibited the phosphorylation of fibroblast growth factor receptors 1 and 3. In a bleomycin-induced murine lung fibrosis model, IM-1918 profoundly reduced fibrotic areas and decreased collagen and α-smooth muscle actin accumulation. These results suggest that IM-1918 can be applied to treat lung fibrosis.

5-Fluorouracil as a Tumor-Treating Field-Sensitizer in Colon Cancer Therapy.

Colorectal cancer (CRC) is a major cause of mortality that can be treated effectively with chemotherapy and radiotherapy, although resistance to these therapeutic modalities often occurs. Tumor-treating fields (TTFields) can block tumor growth by selectively impairing tumor cell division. In this study, we investigated the mechanism by which 5-fluorouracil (5-FU) sensitizes tumor cells to TTFields. Human HCT116 and SW480 CRC cells were treated with 5-FU and/or TTFields, and characterized in vitro in terms of cell viability, apoptosis through reactive oxygen species production, autophagy, and metastatic potentials. The biological effects of 5-FU and/or TTFields were studied via positron emission tomography and computed tomography on xenograft tumor growth and were confirmed with organoid models of patients. Our results revealed that combination treatment with 5-FU and TTFields increased the efficiency of TTFields therapy in colon cancer cells by downregulating signaling pathways associated with cell proliferation, survival, cell invasion, and migration while upregulating pathways mediating apoptosis and autophagic cell death. The novel mechanistic insights gleaned in this study suggest that combination therapy with TTFields and 5-FU may be effective in treating CRC, although safety and efficacy testing in patients with CRC will need to be performed before this strategy can be implemented clinically for TTF-sensitization.

A Small Compound KJ-28d Enhances the Sensitivity of Non-Small Cell Lung Cancer to Radio- and Chemotherapy.

We previously reported on a poly (ADP-ribose) polymerase (PARP) 1/2 inhibitor N-(3-(hydroxycarbamoyl)phenyl)carboxamide (designated KJ-28d), which increased the death of human ovarian cancer BRCA1-deficient SNU-251 cells. In the present study, we further investigated the antitumor activities of KJ-28d in BRCA-proficient non-small cell lung cancer (NSCLC) cells to expand the use of PARP inhibitors. KJ-28d significantly inhibited the growth of NSCLC cells in vitro and in vivo, and induced DNA damage and reactive oxygen species in A549 and H1299 cells. Combined treatment with KJ-28d and ionizing radiation led to increased DNA damage responses in A549 and H1299 cells compared to KJ-28d or ionizing radiation alone, resulting in apoptotic cell death. Moreover, the combination of KJ-28d plus a DNA-damaging therapeutic agent (carboplatin, cisplatin, paclitaxel, or doxorubicin) synergistically inhibited cell proliferation, compared to either drug alone. Taken together, the findings demonstrate the potential of KJ-28d as an effective anti-cancer therapeutic agent for BRCA-deficient and -proficient cancer cells. KJ-28d might have potential as an adjuvant when used in combination with radiotherapy or DNA-damaging agents, pending further investigations.