[Corrigendum] Increased infiltration of macrophages to radioresistant lung cancer cells contributes to the development of the additional resistance of tumor cells to the cytotoxic effects of NK cells.

Subsequently to the publication of the above paper, the authors have realized that the western blots featured in Fig. 5B were inadvertently copied across from Fig. 4B owing to an error made during the figure compilation process.

Glucocorticoid receptor upregulation increases radioresistance and triggers androgen independence of prostate cancer.

Background: Despite the overall success of radiotherapy, a significant number of patients develop radioresistance, which leads to local regional recurrence and distant metastasis. We studied whether repeated radiation treatment promotes androgen-independent survival of prostate cancer (PCa) cells and their metastatic potential. We also studied whether glucocorticoid receptor (GR) increase in radioresistant cells is associated with acquisition of these aggressive characteristics.

Radiation-induced glucocorticoid receptor promotes CD44+ prostate cancer stem cell growth through activation of SGK1-Wnt/β-catenin signaling.

We observed cancer stem cell (CSC) population increase in radioresistant LNCaP (LNCaPR18) and C4-2 (C4-2R26) prostate cancer (PCa) cells compared with respective parental cells. Since the CD44 level increase was most significant in radioresistant PCa cells compared with parental cells among CSC markers tested, we isolated the CD44+ population from LNCaP/LNCaPR18 and C4-2/C4-2R26 cell sets via the immunomagnetic separation method and used them as CSC sources. We detected lower AR level, but higher glucocorticoid receptor (GR) level in CD44+ CSCs than CD44- non-CSCs.

IL-6 signaling contributes to radioresistance of prostate cancer through key DNA repair-associated molecules ATM, ATR, and BRCA 1/2.

Purpose: To study an association between IL-6 signaling and resistance to radiotherapy of prostate cancer (PCa) and explore the molecular mechanisms involved.

Methods: IL-6 expressing C4-2 and CWR22Rv1 (C4-2IL-6/CWRIL-6) and vector control (C4-2vec/CWRvec) cell lines were developed. Radiation-sensitivities of these cells were compared in clonogenic assay, Comet assay, and γH2AX staining.

Preclinical study using androgen receptor (AR) degradation enhancer to increase radiotherapy efficacy via targeting radiation-increased AR to better suppress prostate cancer progression.

Background: While androgen deprivation therapy (ADT) and radiotherapy (RT) are currently used together to treat locally advanced prostate cancer (PCa), RT might have the adverse effect of increasing the PCa androgen receptor (AR) protein expression, which might then increase the resistance to continued RT.

Methods: We used multiple assays for RT sensitivity, protein and RNA expression of AR and related DDR genes, ROS level, DNA damage/repair level, cell cycle and apoptosis. All statistical comparisons were analyzed with t-test or one-way ANOVA.

NFκB and TNFα as individual key molecules associated with the cisplatin-resistance and radioresistance of lung cancer.

Cisplatin-resistant (A549CisR and H292CisR) and radioresistant (A549R26 and H292R22) sub-line non-small cell lung cancer (NSCLC) cells were developed in our lab by long term treatment of parental cells with cisplatin or radiation. Our data showed no cross-resistance between these two sets of cell lines, indicating that molecular mechanisms of developing each resistance may be different. Using these sub-line cells, we sought to reveal the most significantly up-regulated molecules in cisplatin-resistant and radioresistant lung cancer cells, compared with parental cells.

RETRACTED: Neuroendocrine differentiation contributes to radioresistance development and metastatic potential increase in non-small cell lung cancer.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).

Increased infiltration of macrophages to radioresistant lung cancer cells contributes to the development of the additional resistance of tumor cells to the cytotoxic effects of NK cells.

In this study, in order to investigate the effects of increased macrophage infiltration to radioresistant lung tumors in regulating natural killer (NK) cell-mediated immunity, we examined whether the treatment of radioresistant cells with conditioned medium (CM) from phorbol myristate acetate (PMA)/interleukin (IL)-4 treated THP-1 cells (used as a tumor-associated macrophage source) leads to the development of the additional resistance of tumor cells to NK cell cytotoxicity. We found that the susceptibility of THP-1 CM-treated radioresistant cells to NK cell cytotoxicity was decreased compared to the non-treated cells. In addition, it was found that such a decreased susceptibility was associated with increased programmed death receptor ligand 1 (PD-L1) and decreased natural killer group 2D (NKG2D) ligand levels in tumor cells.

In vitro-induced M2 type macrophages induces the resistance of prostate cancer cells to cytotoxic action of NK cells.

Previous reports, including our experimental results, showed that macrophages migrate to prostate cancer (PCa) cells. We tested whether the migrated macrophages affect the susceptibility of castration-resistant PCa (CRPC) cells to cytotoxic actions of natural killer (NK) cells. We found treatment of tumor cells with the conditioned media (CM) of the PMA/IL-4 treated THP-1 cells (M2 type macrophages) (THP-1 CM) decreased the susceptibility of tumor cells to NK cell cytotoxicity, as a result of increased programmed death receptor ligand 1 (PD-L1) and decreased NK group 2D (NKG2D) ligands in CRPC cells.

Adipocytes affect castration-resistant prostate cancer cells to develop the resistance to cytotoxic action of NK cells with alterations of PD-L1/NKG2D ligand levels in tumor cells.

Background: Obesity affects prostate cancer (PCa) progression, and the periprostatic adipose tissue adjacent to the prostate is considered a driving force of disease progression. Adipocytes are the main cell population in adipose tissues and their paracrine role contributes to PCa progression, however its implication in modulating immune reactions remains largely unknown. We investigated the adipocyte role in controlling the susceptibility of castration-resistant PCa (CRPC) cells to the cytotoxic action of natural killer (NK) cells.

FASN-TGF-β1-PD-L1 axis contributes to the development of resistance to NK cell cytotoxicity of cisplatin-resistant lung cancer cells.

Cisplatin remains the most effective therapy for non-small cell lung cancer (NSCLC). We previously have found cisplatin-resistant lung cancer cells (A549CisR and H157CisR) were more resistant to natural killer (NK) cell-mediated cytotoxicity than parental cells. We also discovered that fatty acid synthase (FASN) levels in cisplatin-resistant cells were significantly higher than in parental cells.

Radiation alters PD-L1/NKG2D ligand levels in lung cancer cells and leads to immune escape from NK cell cytotoxicity via IL-6-MEK/Erk signaling pathway.

We investigated whether radiation influences the susceptibility of non-small cell lung cancer (NSCLC) cells to NK cell mediated cytotoxicity. We found radiation treatment increased expression of programmed cell death ligand 1 (PD-L1), but decreased NK group 2, member D (NKG2D) ligand expressions in A549 and H157 NSCLC cells. Both types of changes would have protected tumor cells from the cytotoxic action of NK cells.

Inhibition of IL-6-JAK/Stat3 signaling in castration-resistant prostate cancer cells enhances the NK cell-mediated cytotoxicity via alteration of PD-L1/NKG2D ligand levels.

To investigate whether IL-6 signaling affects the susceptibility of castration-resistant prostate cancer (CRPC) cells to cytotoxic action of natural killer (NK) cells, CRPC cell lines (having different IL-6 levels) were developed by lentiviral transduction. While observing no secreted IL-6 level in parental C4-2 and CWR22Rv1 cells, we found the IL-6 expression/secretion in these cells was induced after the transduction process and the IL-6 level difference in C4-2siIL-6/sc and CWR22siIL-6/sc cell CRPC cell sets could be detected. We then found that IL-6-knockdown cells were more susceptible to NK cell cytotoxicity than control cells due to lowered programmed death receptor ligand 1 (PD-L1) and increased NK group 2D (NKG2D) ligand levels.

Enhancing NK cell-mediated cytotoxicity to cisplatin-resistant lung cancer cells via MEK/Erk signaling inhibition.

Major progress has been made clinically in inhibiting the programmed death receptor 1 (PD-1)/PD-L1 interaction to enhance T cell-mediated immune function, yet the effectiveness of anti-PD-L1/PD-1 agents in enhancing natural killer (NK) cell's function remains largely unknown. Susceptibilities of cisplatin-resistant A549CisR and H157CisR cells vs. parental cells to the cytotoxic action of NK cells were examined.

Simultaneous targeting of ATM and Mcl-1 increases cisplatin sensitivity of cisplatin-resistant non-small cell lung cancer.

Development of cisplatin-resistance is an obstacle in non-small cell lung cancer (NSCLC) therapeutics. To investigate which molecules are associated with cisplatin-resistance, we analyzed expression profiles of several DNA repair and anti-apoptosis associated molecules in parental (A549P and H157P) and cisplatin-resistant (A549CisR and H157CisR) NSCLC cells. We detected constitutively upregulated nuclear ATM and cytosolic Mcl-1 molcules in cisplatin-resistant cells compared with parental cells.

IL-6 Mediates Macrophage Infiltration after Irradiation via Up-regulation of CCL2/CCL5 in Non-small Cell Lung Cancer.

Radiotherapy is effective in reducing primary tumors, however, it may enhance macrophage infiltration to tumor sites, accelerating tumor progression in several ways. We investigated whether radiation can increase macrophage infiltration into non-small cell lung carcinoma (NSCLC) cells. Analysis of in vitro macrophage (differentiated THP-1 cells) migration to either nonirradiated or irradiated tumor cells showed increased migration to the irradiated tumor cells.

A FASN-TGF-β1-FASN regulatory loop contributes to high EMT/metastatic potential of cisplatin-resistant non-small cell lung cancer.

Cisplatin-resistant A549CisR and H157CisR cell lines were developed by treating parental A549 (A549P) and H157 (H157P) cells. These cisplatin-resistant cells showed slight growth retardation, but exhibited higher epithelial-mesenchymal transition (EMT) and increased metastatic potential compared to parental cells. We observed a highly up-regulated fatty acid synthase (FASN) level in A549CisR and H157CisR cells compared to parental cells and the up-regulation of FASN was also detected in A549P and H157P cells after short time treatment with cisplatin, suggesting that the high level of FASN in cisplatin-resistant cells may be from the accumulated cellular responses during cisplatin-resistance developmental process.

Cisplatin treatment increases stemness through upregulation of hypoxia-inducible factors by interleukin-6 in non-small cell lung cancer.

Cisplatin-resistant A549 and H157 (A549CisR and H157CisR) non-small cell lung cancer cells show increased stemness of cancer stem cells (CSCs) compared to their parental cells. We investigated whether interleukin-6 (IL-6) signaling contributes to this increased stemness in cisplatin-resistant cells. When A549CisR and H157CisR cells were treated with neutralizing IL-6 antibody, decreased cisplatin resistance was observed, whereas IL-6 treatment of parental cells resulted in increased cisplatin resistance.

IL-6 promotes growth and epithelial-mesenchymal transition of CD133+ cells of non-small cell lung cancer.

We examined IL-6 effects on growth, epithelial-mesenchymal transition (EMT) process, and metastatic ability of CD133+ and CD133- cell subpopulations isolated from three non-small cell lung cancer (NSCLC) cell lines: A549, H157, and H1299. We developed IL-6 knocked-down and scramble (sc) control cells of A549 and H157 cell lines by lentiviral infection system, isolated CD133+ and CD133- sub-populations, and investigated the IL-6 role in self-renewal/growth of these cells. IL-6 showed either an inhibitory or lack of effect in modulating growth of CD133- cells depending on intracellular IL-6 levels, but there was higher self-renewal ability of IL-6 expressing CD133+ cells than IL-6 knocked down cells, confirming the promoter role of IL-6 in CD133+ cells growth.