Tumor-associated macrophage-derived inflammatory cytokine enhances malignant potential of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an asbestos-related aggressive malignant neoplasm. Due to the difficulty of achieving curative surgical resection in most patients with MPM, a combination chemotherapy of cisplatin and pemetrexed has been the only approved regimen proven to improve the prognosis of MPM. However, the median overall survival time is at most 12 mo even with this regimen. There has been therefore a pressing need to develop a novel chemotherapeutic strategy to bring about a better outcome for MPM. We found that expression of interleukin-1 receptor (IL-1R) was upregulated in MPM cells compared with normal mesothelial cells. We also investigated the biological significance of the interaction between pro-inflammatory cytokine IL-1ß and the IL-1R in MPM cells. Stimulation by IL-1ß promoted MPM cells to form spheroids along with upregulating a cancer stem cell marker CD26. We also identified tumor-associated macrophages (TAMs) as the major source of IL-1ß in the MPM microenvironment. Both high mobility group box 1 derived from MPM cells and the asbestos-activated inflammasome in TAMs induced the production of IL-1ß, which resulted in enhancement of the malignant potential of MPM. We further performed immunohistochemical analysis using clinical MPM samples obtained from patients who were treated with the combination of platinum plus pemetrexed, and found that the overexpression of IL-1R tended to correlate with poor overall survival. In conclusion, the interaction between MPM cells and TAMs through a IL-1ß/IL-1R signal could be a promising candidate as the target for novel treatment of MPM (Hyogo College of Medicine clinical trial registration number: 2973).

EphA2 inhibition suppresses proliferation of small-cell lung cancer cells through inducing cell cycle arrest.

Small-cell lung cancer (SCLC) is characterized by one of neuroendocrine tumors, and is a clinically aggressive cancer due to its rapid growth, early dissemination, and rapid acquisition of multidrug resistance to chemotherapy. Moreover, the standard chemotherapeutic regimen in SCLC has not changed for three decades despite of the dramatic therapeutic improvement in non-SCLC. The development of a novel therapeutic strategy for SCLC has become a pressing issue. We found that expression of Eph receptor A2 (EphA2) is upregulated in three of 13 SCLC cell lines and five of 76 SCLC tumor samples. Genetic inhibition using siRNA of EphA2 significantly suppressed the cellular proliferation via induction of cell cycle arrest in SBC-5 cells. Furthermore, small molecule inhibitors of EphA2 (ALW-II-41-27 and dasatinib) also exclusively inhibited proliferation of EphA2-positive SCLC cells by the same mechanism. Collectively, EphA2 could be a promising candidate as a therapeutic target for SCLC.

Analysis of Pleiotropic Effects of Nivolumab in Pretreated Advanced or Recurrent Non-small Cell Lung Cancer Cases.

BACKGROUND/AIM: Nivolumab is an immune checkpoint inhibitor for advanced non-small cell lung cancer (NSCLC). We investigated the safety and efficacy of nivolumab by analyzing the response factor, adverse effects (AE), and the post-treatment condition of pretreated advanced or recurrent NSCLC patients. PATIENTS AND METHODS: Nivolumab (3 mg/kg) was administered to 79 pre-treated NSCLC patients from December 2015 to January 2018. Nivolumab efficacy and AE were assessed using the Response Evaluation Criteria in Solid Tumors and the Common Terminology Criteria, respectively. RESULTS: Progression-free survival (PFS) was significantly prolonged in cases where the therapeutic effect of the pretreatment was a partial response (p=0.0004). Five cases (6.3%) experienced grade 3-4 AEs. PFS was significantly prolonged in the skin rash group versus the non-skin rash group, and in patients where nivolumab treatment was discontinued. CONCLUSIONS: Long-term survival was observed in patients with skin rash. Therapeutic effect of nivolumab immediately following its administration appears to be favorable for survival.

Double cancer comprising malignant pleural mesothelioma and squamous cell carcinoma of the lung treated with radiotherapy: A case report.

Pleurectomy/decortication (P/D) is the surgical treatment of choice for early malignant mesothelioma, but it remains unclear whether radiotherapy along with P/D should be used as multimodal treatment for this disease. We herein present the case of a 76-year-old man with a history of asbestos exposure who was diagnosed with left-sided malignant pleural mesothelioma in February 2010. The patient underwent chemotherapy with a combination of cisplatin and pemetrexed and achieved stable disease, after which time he was kept under observation. A positron emission tomography/computed tomography scan performed in February 2011 revealed nodular shadows with fluorodeoxyglucose uptake in S3 of the left lung; using bronchoscopy, the patient was diagnosed with stage IIB (cT3N0M0) primary squamous cell carcinoma. Chemoradiotherapy with vinorelbine and 60 Gy/20 fr radiotherapy was performed, and a partial response was obtained, suggesting that the radiotherapy used to treat the carcinoma of the lung may have also helped control the disease activity of the pre-existing mesothelioma. The present case indicates the value of radiotherapy in the treatment of malignant mesothelioma. The aim of the present study was to examine the possibility of new multimodal treatments for mesothelioma, along with a discussion of the relevant literature.

Successful Treatment of Pulmonary Pleomorphic Carcinoma with Nivolumab: A Case Report.

Pulmonary pleomorphic carcinoma (PPC) has a poor prognosis due to the poor results of treatment with systemic chemotherapy. We report the case of a 73-year-old woman with PPC who showed a favorable response to nivolumab. As first-line treatment for postoperative recurrence, she received carboplatin and nanoparticle albumin-bound paclitaxel. However, 12 months later, a new metastatic lymph node appeared. Nivolumab was administered as second-line treatment, and the patient showed a favorable prolonged response. The effects of treatment of PPC with nivolumab seem promising. The results of a future prospective study are expected to identify indicators for the treatment of PPC.

Enhancing effect of connexin 32 gene on vinorelbine-induced cytotoxicity in A549 lung adenocarcinoma cells.

PURPOSE: Connexin (Cx) genes exert negative growth effects on tumor cells with certain cell specificity, and tumor-suppressive effects of the Cx genes contribute to enhancement of chemotherapeutical agents-induced cytotoxicity in some cancer cells. Since we and others have been reported that Cx32 acts as a tumor suppressor gene in lung adenocarcinomas, this study was undertaken to estimate if the combination of Cx32-dependent tumor-suppressive effect and vinorelbine (VBN), a chemotherapeutic agent which has been utilized for clinical lung adenocarcinoma treatment, could be effective in enhancing the sensitivity of the lung cancer to VBN treatment. METHODS: We established the A549 cells (a human lung adenocarcinoma cell line) which had stable expression of Cx32 and estimated effect of Cx32 on VBN-induced cytotoxicity in the established cells. RESULTS: Cx32 expression in A549 cells significantly potentiated VBN-induced cytotoxicity on the cells due to enhancement of apoptosis induction. The enhancing cytotoxicity in A549 cells by Cx32 mainly depended on a decrease in expression of multi-drug resistance-1 (MDR-1) gene responsible for reduction of VBN accumulation into the cells. We also observed that silencing of Cx32 by siRNA treatment elevated the expression level of MDR-1 mRNA in A549 cells and that inhibition of MDR-1 gene product-dependent function enhanced VBN-induced cytotoxicity in the cells. CONCLUSION: These results suggest that Cx32 contributes to the enhancement of VBN-induced cytotoxicity in A549 cells via the reduction of MDR-1 expression.

First-line chemotherapy with pemetrexed plus cisplatin for malignant peritoneal mesothelioma.

BACKGROUND: Mesothelioma of peritoneal origin has wider variation in treatment outcomes than mesothelioma of pleural origin, likely because peritoneal mesothelioma comprises borderline malignant variants and aggressive malignant peritoneal mesothelioma (MPeM). This study retrospectively evaluates the efficacy of first-line systemic pemetrexed and cisplatin chemotherapy in MPeM. RESEARCH DESIGN AND METHODS: Twenty-four patients with histologically proven MPeM were treated with pemetrexed plus cisplatin as a first-line systemic chemotherapy. The response was evaluated radiologically according to standard Response Evaluation Criteria In Solid Tumors (RECIST) criteria. Twenty-two patients underwent 18F-fluorodeoxyglucose positron emission tomography/(FDG-PET)/computed tomography(CT) at baseline, and 13 were eligible for metabolic assessment. RESULTS: Two complete responses and 9 partial responses were achieved. Overall response rate and disease control rate were 45.8% and 91.7%, respectively. Median progression-free survival and median overall survival were 11.0 months and 15.8 months, respectively. Wet- type MPeM had significantly longer survival (40.9 months median) than other clinical types (15.5 months) (P = 0.045). The baseline maximum standardized uptake value in 22 patients was 8.93 (range, 2.5-16.77). CONCLUSIONS: Systemic pemetrexed plus cisplatin is active for MPeM. Disparity with the outcome of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) needs to receive more emphasis, since peritoneal mesothelioma has a 5-year survival rate of 50%.

Connexin32 as a tumor suppressor gene in a metastatic renal cell carcinoma cell line.

Connexin genes expressing gap junction proteins have tumor-suppressive effects on primary cancers with certain cell specificity, but the suppressive effects on metastatic cancers are still conflicting. In this study, we show that connexin32 (Cx32) has a strong tumor-suppressive effect on a human metastatic renal cell carcinoma cell line (Caki-1 cell). Cx32 expression in Caki-1 cells reduced in vitro malignant phenotypes of the cells such as anchorage independency and invasion capacity. Furthermore, the Cx32 expression drastically reduced the development of Caki-1 cells in nude mice. We also determined that Cx32 reduced the malignant phenotypes in Caki-1 cells mainly through the inactivation of Src signaling. Especially, Cx32-dependent inactivation of Src decreased the production of vascular epithelial growth factor (VEGF) via the suppression of signal transducers and activators of transcription 3 (Stat3) activation, and we confirmed this result using short interfering RNA. In nude mice, Cx32-transfected Caki-1 cells showed lower serum level of VEGF comparing mock transfectant, and the development of the cells in nude mice positively related to the VEGF level. These data suggest that Cx32 acts as a tumor suppressor gene in Caki-1 cells and that the tumor-suppressive effect partly depends on the inhibition of Src-Stat3-VEGF signal pathway.

Inhibition of Src activity enhances the tumor-suppressive effect of the connexin 32 gene in Caki-1 renal cancer cells.

Connexin (Cx) genes exert negative growth effects on tumor cells with certain cell specificity. We have recently reported that Cx32 acts as a tumor suppressor gene in a metastatic renal cancer cell line (Caki-1) due to the inactivation of Src. In line with the previous study, here we investigated if an Src family inhibitor (PP1) could enhance the tumor-suppressive effect of Cx32 in Caki-1 cells from human metastatic renal cell carcinoma. We examined the difference in the cytotoxic effect of PP1 on two cell clones, Cx32-transfected Caki-1 cells (Caki-1T) and mock-transfected Caki-1 cells (Caki-1W), in vitro as well as in vivo. PP1 showed more cytotoxic effect on Caki-1T than on Caki-1W at lower doses. This reinforcement was also observed in a xenograft model of nude mice. The in vitro reinforcement of the cytotoxic effect depended not only on control of cell-cycle transition but also on the induction of apoptosis, and the occurrence of the event was mostly caused by potential inhibition of Src activity in Caki-1T. Also, under a hypoxic condition, which is a typical environment of tumor tissue, Cx32 suppressed hypoxia-induced Src activation, and PP1 enhanced cytotoxicity in Caki-1T. These results suggest that, in addition to the Cx32-dependent tumor-suppressive effect, the concomitant inhibition of Src by PP1 is an effective procedure to induce a cytotoxic effect in Caki-1 cells.

A Src family inhibitor (PP1) potentiates tumor-suppressive effect of connexin 32 gene in renal cancer cells.

Connexin (Cx) genes exert negative growth effects on tumor cells with certain cell specificity. We have recently reported that Cx32 acts as a tumor suppressor gene in renal cancer cells due to the inhibition of Src-dependent signaling. In line with the previous study, here we examined if a Src family inhibitor (PP1) could potentiate tumor-suppressive effect of Cx32 in Caki-2 cell from human renal cell carcinoma. In order to clarify the potentialization of PP1, using Cx32-transfected Caki-2 cells and mock-transfected Caki-2 cells, we estimated difference in cytotoxic effect of PP1 on the two cell clones in vitro as well as in vivo. PP1 showed more cytotoxic effect on Caki-2 cells having Cx32 positive expression than that of Cx32 negative expression at lower doses. This potentialization was also observed in xenograft model of nude mice. The potentialization of the effect mainly depended on the induction of apoptosis but not the control of cell growth. In conjugation with this event, the reduction of anti-apoptotic molecules (Bcl-2 and Bcl-xL) was caused by the combination of Cx32 expression and PP1 treatment in Caki-2 cells. These results suggest that PP1 potentiates tumor-suppressive effect of connexin 32 gene in renal cancer cells through the reduction of anti-apoptotic molecules.

Connexin 32 as an anti-invasive and anti-metastatic gene in renal cell carcinoma.

Cellular homeostasis in many organs is maintained via gap junctions composed of connexin (Cx), a large protein family with a number of isoforms. In fact, gap junctional intercellular communication (GJIC) is actively involved in all aspects of the cellular life cycle, ranging from cell growth to cell death. It has been well known that Cx gene acts as a tumor suppressor gene due to the maintenance of cellular homeostasis via GJIC. On the other hand, recent data show that GJIC-independent function for Cx gene contributes to tumor-suppressive effect of the gene with cell certain specificity. However, the mechanistic aspect of the GJIC-independent function remains largely unknown. In this review, we briefly summarize the tumor-suppressive effects of Cx genes, refer to a new aspect of Cx32 as an anti-invasive and anti-metastatic gene against renal cell carcinoma in a GJIC-independent function and establishment of a new cancer therapy based on the new function of Cx32.

Cytotoxic effect of the Her-2/Her-1 inhibitor PKI-166 on renal cancer cells expressing the connexin 32 gene.

We have reported that connexin (Cx) 32 acts as a tumor suppressor gene in renal cancer cells partly due to Her-2 inactivation. Here, we determined if a Her-2/Her-1 inhibitor (PKI-166) can enhance the tumor-suppressive effect of Cx32 in Caki-2 cells from human renal cell carcinoma. The expression of Cx32 in Caki-2 cells was required for PKI-166-induced cytotoxic effect at lower doses. The cyctotoxicity was dependent on the occurrence of apoptosis and partly mediated by Cx32-driven gap junction intercellular communications. These results suggest that PKI-166 further supports the tumor-suppressive effect of the Cx32 gene in renal cancer cells through the induction of apoptosis.

Negative growth control of renal cell carcinoma cell by connexin 32: possible involvement of Her-2.

Connexin (Cx) genes have negative growth effects on tumor cells with certain cell specificity. We have previously reported that Cx32 is specifically downregulated in human renal cell carcinoma cell (RCC) lines as well as cancerous regions of kidneys and that the Cx is expressed in the progenitor cells of the carcinoma. However, the precise role of Cx32 in growth control of RCC cells remains unknown. In this study, we examined whether Cx32 could act in growth control against a human RCC cell, Caki-2 cell. In order to estimate the cell growth control, we established Caki-2 cells that have stable expression of Cx32 genes. Cx32 expression in Caki-2 cells induced contact inhibition of growth and reduced anchorage-independent growth ability, but did not significantly affect lag phase growth rates. This growth control by Cx32 was dependent on the inhibition of the cell-cycle transition from G1 to S phase at high cell density, and the inhibition of the cell-cycle transition related to the suppression of Her-2 activation. Furthermore, the suppression of Cx32 expression in Caki-2 cells by short interfering RNA induced the activation of Her-2. These data suggest that Cx32 has negative growth control of Caki-2 cells, partly due to the inhibition of the Her-2 activation.