Esophageal Squamous Cell Carcinoma Xenograft Model Research Articles

Recombinant measles virus vaccine rMV-Hu191 exerts an oncolytic effect on esophageal squamous cell carcinoma via caspase-3/GSDME-mediated pyroptosis

Oncolytic viruses have recently been proven to be an effective and promising cancer therapeutic strategy, but there is rare data about oncolytic therapy in esophageal squamous cell carcinoma (ESCC), especially oncolytic measles virotherapy. Therefore, this study aimed to explore whether the recombinant measles virus vaccine strain rMV-Hu191 has an oncolytic effect against ESCC cells in vitro and in vivo and elucidate the underlying mechanisms. Our results showed that rMV-Hu191 could efficiently replicate in and kill ESCC cells through caspase-3/GSDME-mediated pyroptosis. Mechanistically, rMV-Hu191 triggers mitochondrial dysfunction to induce pyroptosis, which is mediated by BAK (BCL2 antagonist/killer 1) or BAX (BCL2 associated X). Further analysis revealed that rMV-Hu191 activates inflammatory signaling in ESCC cells, which may enhance the oncolytic efficiency. Moreover, intratumoral injection of rMV-Hu191 induced dramatic tumor regression in an ESCC xenograft model. Collectively, these findings imply that rMV-Hu191 exhibits an antitumor effect through BAK/BAX-dependent caspase-3/GSDME-mediated pyroptosis and provides a potentially promising new therapy for ESCC treatment.

CircRNA CircRIMS is Overexpressed in Esophageal Squamous Cell Carcinoma and Downregulate miR-613 Through Methylation to Increase Cell Proliferation.

PurposeCircRNA CircRIMS has been characterized as an oncogenic circRNA in gastric cancer, while its role in other cancers is unknown. This study aimed to explore the role of CircRIMS in esophageal squamous cell carcinoma (ESCC).Patients and MethodsTissues collected from 60 ESCC patients were subjected to extractions of total RNA and RT-qPCRs to analyze the differential expression of CircRIMS and miR-613. The 60 ESCC patients were followed up for 5 years to analyze the prognostic value of CircRIMS for ESCC. The interaction between CircRIMS and miR-613 was showed by luciferase activity assay and fluorescence in situ hybridization. The role of CircRIMS in regulating miR-613 expression and methylation was analyzed by overexpression experiments, RT-qPCRs and Western blot assay. The role of CircRIMS and miR-613 in regulating cell proliferation was analyzed using the BrdU assay. ESCC xenograft model was used to demonstrate the role of CircRIMS and miR-613 in vivo.ResultsWe found that CircRIMS was overexpressed in ESCC and predicted poor survival. In addition, miR-613 was under expressed in ESCC and inversely correlated with CircRIMS. In ESCC cells, CircRIMS overexpression decreased the expression of miR-613 and increased the methylation of miR-613 gene. Cell proliferation assay showed that CircRIMS overexpression reduced the inhibitory effects of miR-613 overexpression on cell proliferation. Animal experience finally illustrated that CircRNA CircRIMS downregulated miR-613 through methylation to promote tumor growth.ConclusionTherefore, CircRIMS may downregulate miR-613 through methylation to increase cell proliferation in ESCC.

Cabozantinib (XL184) and R428 (BGB324) Inhibit the Growth of Esophageal Squamous Cell Carcinoma (ESCC).

Esophageal squamous cell carcinoma (ESCC) is a deadly disease for which no effective targeted therapeutic agent has been approved. Both AXL and c-MET have been reported to be independent prognostic factors for ESCC. Thus, inhibitors of AXL/c-MET might have great potential as targeted therapy for ESCC. In the current study, we evaluated the therapeutic potential of the AXL/c-MET selective inhibitors, R428 and cabozantinib, in cell and mouse xenograft models. We demonstrated that both R428 and cabozantinib significantly inhibited the growth of CE81T and KYSE-70 ESCC cells and showed by wound-healing assay that they both inhibited ESCC cell migration. In the animal model, ESCC xenograft models were established by injecting KYSE-70 cells with Matrigel into the upper back region of NOD-SCID male mice followed by treatment with vehicle control, R428 (50 mg/kg/day), cisplatin (1.0 mg/kg), or cabozantinib (30 mg/kg/day) for the indicated number of days. R428 alone significantly inhibited ESCC tumor growth compared to the vehicle; however, no synergistic effect with cisplatin was observed. Notably, the dramatic efficacy of cabozantinib alone was observed in the mouse xenograft model. Collectively, our study demonstrated that both cabozantinib and R428 inhibit ESCC growth in cell and xenograft models. The results reveal the great potential of using cabozantinib for targeted therapy of ESCC.

Abstract 309: FAK blockade enhances antitumor effect of BTK inhibitor in esophageal squamous cell carcinoma via EGFR-ERK-Akt pathway inhibition

Abstract Background: Esophageal squamous cell carcinoma (ESCC) is a fatal disease with poor prognosis and lack of effective targeted therapy. Recently, some researches have shown that BTK can be a novel therapeutic target for esophageal cancer, while the mechanism remains unknown. In addition, FAK is one of the important factors to promote the metastasis of esophageal cancer. In this study, we sought to explore the synergistic antitumor effect and underline mechanism of combining BTK inhibitor Ibrutinib with a novel FAK inhibitor APG-2449 for esophageal squamous cell carcinoma. Methods: Cell viability and growth inhibition were determined by CCK-8 assay and colony formation assay. Migration ability was detected by Transwell assay. EMT markers and ki67 were measured by RT-qPCR. Cell cycle analysis and apoptosis were confirmed by flow cytometry. Western Blot analysis and siRNA interference for mechanism exploration. ESCC xenograft models were established to evaluated the synergistic antitumor effect in vivo. Results: We found that ESCC cell lines harbor EGFR or c-myc-amplified exhibited more sensitive to Ibrutinib inhibition. Moreover, Ibrutinib combined with APG-2449 showed synergistic inhibition of cell proliferation in ESCC cell lines. By analyzing data from the Gene Expression Profiling Interactive Analysis database, we found that EGFR expression positively correlated with FAK expression in ESCC samples. The combination of Ibrutinib and APG-2449 exerted obviously synergistic apoptosis induction and colony formation inhibition. Furthermore, we found that Ibrutinib combined with APG-2449 could induce more cancer cells arrested in G1/S phase. In addition, the co-treatment of Ibrutinib and APG-2449 could significantly suppress ESCC cells migration by upregulating E-cadherin. Ibrutinib alone could down-regulate the protein expression of p-EGFR and p-ERK. Moreover, combination treatment significantly reduced the expression of p-Akt and p-c-myc, and upregulated P21 and PUMA expression. In ESCC xenotransplantation models, single therapy with either Ibrutinib or APG-2449 was equivalent in delaying tumor growth, while the combination therapy demonstrated more significantly tumor growth suppression. Conclusions: Taken together, our data strongly suggest that the combination of FAK inhibitor APG-2449 and Ibrutinib provide an effective and precise therapeutic strategy for treating esophageal squamous cell carcinoma. Citation Format: Qiu-Yun Luo, Su-Na Zhou, Wen-Tao Pan, Meng-xian Pan, Lu-ping Yuan, Lin Zhang, Xiang-Lei Yan, Yu-xin Zhang, Jian Sun, Miaozhen Qiu, Da-Jun Yang. FAK blockade enhances antitumor effect of BTK inhibitor in esophageal squamous cell carcinoma via EGFR-ERK-Akt pathway inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 309.

CDK11p110 plays a critical role in the tumorigenicity of esophageal squamous cell carcinoma cells and is a potential drug target

ABSTRACT Esophageal squamous cell carcinoma (ESCC) is a serious malignancy with limited options for targeted therapy. The exploration of novel targeted therapies for combating ESCC is urgently needed. Cyclin-dependent kinases (CDKs) play important roles in the progression of cancers; however, the function of CDK11p110 (cyclin-dependent kinase 11p110) in ESCC is still unknown. Here, we investigated the effects and molecular mechanisms of CDK11p110 in the proliferation and growth of ESCC by examining the expression of CDK11p110 in ESCC tissues and by detecting phenotypic changes in ESCC cells after CDK11p110 knockdown or overexpression in vitro and in vivo. According to the tissue microarray analysis, compared with its expression level in normal tissues, the expression level of CDK11p110 was significantly elevated in ESCC tissues; this result was in concordance with the data in TCGA (The Cancer Genome Atlas) datasets. In addition, RNAi-mediated CDK11p110 silencing exerted a substantial inhibitory effect on the proliferation, clonogenicity and migration ability of ESCC cells. Further study indicated that CDK11p110 knockdown arrested ESCC cells in the G2/M phase of the cell cycle and induced cell apoptosis. Moreover, stable shRNA-mediated CDK11p110 knockdown inhibited tumor growth in an ESCC xenograft model, and overexpression of CDK11p110 enhanced tumor growth. In addition, the Ki67 proliferation index was closely associated with the elevation or depletion of CDK11p110 in vivo. In summary, this study provides evidence that CDK11p110 play a critical role in the tumorigenicity of ESCC cells, which suggests that CDK11p110 may be a promising therapeutic target in ESCC. Abbreviations: CDKs: cyclin-dependent kinases; CDK11: Cyclin-dependent kinase 11; CDK11p110: Cyclin-dependent kinase 11p110, the larger isomer of cyclin-dependent kinase 11; ESCC: esophageal squamous cell carcinoma; FACS: fluorescence-activated cell sorting; FDA: the Food and Drug Administration; TCGA: The Cancer Genome Atlas; TMA: tissue microarray.

PS02.024: PRIMA-1 INDUCES P53-MEDIATED APOPTOSIS BY UPREGULATING NOXA IN ESOPHAGEAL SQUAMOUS CELL CARCINOMA WITH TP53 MISSENSE MUTATION

Abstract Background TP53 is associated with the resistance of cytotoxic treatment and patient prognosis, and the mutation rate of TP53 in esophageal squamous cell carcinoma (ESCC) is extraordinarily high, at over 90%. PRIMA-1 (p53 re-activation and induction of massive apoptosis) has recently been reported to restore wild type activity to mutant p53 and induce massive p53-dependent apoptosis. APR-246 (methylated PRIMA-1) has been tested in a phase I/II clinical trial with promising results; however, the effects and mechanism in ESCC remain unknown. This study was designed to assess the antitumor effect of PRIMA-1 treatment in both ESCC cell lines with different TP53 status and an ESCC xenograft model and uncover the molecular mechanism of PRIMA-1. Methods After evaluating the TP53 mutation status of a panel of eleven ESCC cell lines by Sanger sequencing, we assessed the in vitro effect of PRIMA-1 administration on cells with different p53 status by conducting cell viability and apoptosis assays. The expression levels of proteins in TP53-related pathways were examined by Western blotting, while knockdown studies were conducted to investigate the mechanism underlying PRIMA-1’s function. An ESCC xenograft model was further used to evaluate the therapeutic effect of PRIMA-1 in vivo. Results PRIMA-1 markedly inhibited cell growth and induced apoptosis by upregulating Noxa expression in ESCC cell lines with a TP53 missense mutation, whereas no apoptosis was induced in ESCC with wild type TP53 and with TP53 frameshift and nonsense mutations. Importantly, the knockdown of Noxa cancelled the apoptosis induced by PRIMA treatment in ESCC cell lines with a TP53 missense mutation. PRIMA-1 administration, compared with placebo, showed a significant antitumor effect by inducing Noxa in the xenograft model of an ESCC cell line with a TP53 missense mutation. Conclusion PRIMA-1 exhibits a significant antitumor effect, inducing massive apoptosis through the upregulation of Noxa in ESCC with a TP53 missense mutation. Disclosure All authors have declared no conflicts of interest.

PRIMA-1 induces p53-mediated apoptosis by upregulating Noxa in esophageal squamous cell carcinoma with TP53 missense mutation.

TP53 is associated with the resistance of cytotoxic treatment and patient prognosis, and the mutation rate of TP53 in esophageal squamous cell carcinoma (ESCC) is extraordinarily high, at over 90%. PRIMA‐1 (p53 re‐activation and induction of massive apoptosis) has recently been reported to restore the function of mutant TP53; however, its antitumor effect and mechanism in ESCC remain unclear. After evaluating the TP53 mutation status of a panel of 11 ESCC cell lines by Sanger sequencing, we assessed the in vitro effect of PRIMA‐1 administration on cells with different TP53 status by conducting cell viability and apoptosis assays. The expression levels of proteins in p53‐related pathways were examined by Western blotting, while knockdown studies were conducted to investigate the mechanism underlying PRIMA‐1's function. An ESCC xenograft model was further used to evaluate the therapeutic effect of PRIMA‐1 in vivo. PRIMA‐1 markedly inhibited cell growth and induced apoptosis by upregulating Noxa expression in ESCC cell lines with TP53 missense mutations, whereas no apoptosis was induced in ESCC with wild‐type TP53 and TP53 with frameshift and nonsense mutations. Importantly, the knockdown of Noxa canceled the apoptosis induced by PRIMA treatment in ESCC cell lines with TP53 missense mutations. PRIMA‐1 administration, compared with placebo, showed a significant antitumor effect by inducing Noxa in the xenograft model of an ESCC cell line with a TP53 missense mutation. PRIMA‐1 exhibits a significant antitumor effect, inducing massive apoptosis through the upregulation of Noxa in ESCC with TP53 missense mutations.

Capilliposide C Sensitizes Esophageal Squamous Carcinoma Cells to Oxaliplatin by Inducing Apoptosis Through the PI3K/Akt/mTOR Pathway.

BackgroundAlthough platinum-based chemotherapy is the most effective strategy for esophageal cancer, toxicity and drug resistance limit the dose administration and the application of chemotherapy. Capilliposide C (CPS-C) is isolated from the Chinese herb Lysimachia capillipes Hemsl and is approved to be effective against carcinomas. However, the activity of CPS-C against esophageal cancer remains unclear. The present study was conducted to assess the chemosensitizing effects of CPS-C for enhancing the therapeutic efficacy of oxaliplatin in esophageal squamous carcinoma cells and explore the underlying mechanism.Material/MethodsHuman esophageal squamous cell carcinoma (ESCC) TE-1 and TE-2 were used. Several in vitro and in vivo analyses were carried out, including MTT, Annexin V/PI, Western blot, and TUNEL and immunohistochemistry in a xenograft model.ResultsCPS-C significantly enhanced the proliferative inhibition and apoptotic effect of oxaliplatin in ESCC cells. Oxaliplatin combined with CPS-C decreased the expressions of PI3K, phospho-Akt, phospho-mTOR, Bcl-2, and Bcl-XL, and increased the expression of Bax and caspase-3 significantly compared to oxaliplatin-only treatment. Furthermore, in the ESCC xenograft model, CPS-C significantly enhanced the anti-cancer effects and apoptosis of oxaliplatin.ConclusionsThe results indicated that CPS-C enhanced the anti-proliferative and apoptotic effect of oxaliplatin by modulating the PI3K/Akt/mTOR pathway on ESCC in vitro and in vivo.

Glypican-1 targeted antibody-based therapy induces preclinical antitumor activity against esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) has a poor prognosis despite the development of multimodal therapy. Expression of glypican-1 (GPC1) has been reported to be elevated in a subset of patients with ESCC and associated with chemoresistance. This study aimed to determine the association of GPC1 with ESCC growth and potential usefulness of the GPC1 targeted therapy by monoclonal antibody (mAb) in ESCC. Expression of GPC1 was higher in ESCC tumor tissues than in adjacent non-tumoral tissues and normal tissues. Knockdown of GPC1 decreased growth of ESCC cells and induced apoptosis via inhibition of EGFR, AKT and p44/42-MAPK signaling pathways in vitro. Anti-GPC1 mAb strongly inhibited tumor growth via antibody-dependent cellular cytotoxicity dependent and independent manner in GPC1-positive ESCC xenograft models. Anti-GPC1 mAb also inhibited tumor growth of GPC1 positive ESCC patients derived tumor xenograft models. Furthermore, anti-GPC1 mAb showed a significant tumor growth inhibition with decreased angiogenesis compared with IgG treated controls in ESCC xenografted mice. Treatment with anti-GPC1 mAb was not toxic in mice. Anti-GPC1 mAb may have a potent anti-tumor effect and represent a novel treatment option for patients with GPC1-positive ESCC.

Abstract 4213: Gene therapy for esophageal squamous cell carcinoma using SOCS-1 expressing adenoviral vector

Abstract Objective Esophageal squamous cell carcinoma (ESCC) is the major histological form of oesophageal cancer in East Asian countries. Despite recent improvements in multimodality treatment, including surgery, radiotherapy and chemotherapy, the prognosis for patients with ESCC remains unsatisfactory. Therefore, development of novel therapy is urgently required. Suppressor of cytokine signaling-1 (SOCS-1) has been cloned as a negative regulator of various cytokine signaling. Recently, lines of evidences suggest that overexpression of SOCS-1 has been considered as a promising therapeutic approach for treatment of cancer. This study was aimed to evaluate the therapeutic effect of the overexpression of SOCS-1 by adenoviral vector (AdSOCS-1) against ESCC. METHODS By WST-8 assay, cell growth inhibition via infection with various dose of AdSOCS-1 was evaluated in 11 ESCC cell lines in vitro. We also evaluated the induction of apoptosis by overexpression of SOCS-1 in vitro. To evaluate the therapeutic efficacy of AdSOCS-1, ESCC cell line (TE-8) was subcutaneously implanted into the ICR nu/nu mice. In addition, therapeutic efficacy was also assessed using human xenografts subcutaneously transplanted in imuune-deficient mice. Mice were intra-tumorally injection with AdSOCS-1 or control adenovirus vector (AdLacZ) twice a week for 4weeks. RESULTS Among 11 ESCC cell lines, AdSOCS-1, markedly suppressed proliferation of 8 ESCC cell lines in vitro. AdSOCS-1 strongly induced apoptosis in vitro, via inhibiting JAK/STAT3 pathway. In the TE8 xenograft model, the volume of tumors after therapy in AdSOCS-1 group (1,580 ± 1,005mm3) were lower than that in control group (2,690 ± 1,309mm3). Furthermore, compared with AdLacZ, injection with AdSOCS-1 also inhibited the tumor growth of patient derived ESCC xenografts. CONCLUSIONS Our results indicated that overexpression of SOCS-1 inhibited the progression of ESCC both in ESCC cell lines and ESCC xenograft model derived from patient. SOCS-1 can be a promising novel therapeutic approach for intra-lesional therapy in ESCC. Citation Format: Hisashi Hara, Rie Nakatsuka, Tsuyoshi Takahashi, Satoshi Serada, Minoru Fujimoto, Yasuhiro Miyazaki, Tomoki Makino, Yukinori Kurokawa, Makoto Yamasaki, Hiroshi Miyata, Kiyokazu Nakajima, Shuji Takiguchi, Masaki Mori, Yuichiro Doki, Tetsuji Naka. Gene therapy for esophageal squamous cell carcinoma using SOCS-1 expressing adenoviral vector. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4213. doi:10.1158/1538-7445.AM2015-4213

Macrolide analog F806 suppresses esophageal squamous cell carcinoma (ESCC) by blocking β1 integrin activation.

The paucity of new drugs for the treatment of esophageal squamous cell carcinoma (ESCC) limits the treatment options. This study characterized the therapeutic efficacy and action mechanism of a novel natural macrolide compound F806 in human ESCC xenograft models and cell lines. F806 inhibited growth of ESCC, most importantly, it displayed fewer undesirable side effects on normal tissues in two human ESCC xenograft models. F806 inhibited proliferation of six ESCC cells lines, with the half maximal inhibitory concentration (IC50) ranging from 9.31 to 16.43 μM. Furthermore, F806 induced apoptosis of ESCC cells, contributing to its growth-inhibitory effect. Also, F806 inhibited cell adhesion resulting in anoikis. Mechanistic studies revealed that F806 inhibited the activation of β1 integrin in part by binding to a novel site Arg610 of β1 integrin, suppressed focal adhesion formation, decreased cell adhesion to extracellular matrix and eventually triggered apoptosis. We concluded that F806 would potentially be a well-tolerated anticancer drug by targeting β1 integrin, resulting in anoikis in ESCC cells.

Integrin alpha 6: A novel therapeutic target in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC), the most common subtype of esophageal cancer in East Asian countries, is a devastating disease characterized by distinctly high incidence and mortality rates. Our previous expression profile analysis showed that integrin alpha 6 (ITGA6) is highly expressed in ESCC tissues. To validate cell surface expression of ITGA6 as a novel target in ESCC, we investigated ITGA6 expression in tumor tissue samples and cell lines of ESCC and found that ITGA6 was upregulated in these cells. In vitro knockdown of ITGA6 in ESCC cells resulted in inhibition of cell proliferation, invasion and colony formation. In addition, we demonstrated that ITGA6 associates with integrin beta 4 (ITGB4), and that this heterodimer complex is upregulated in both ESCC tissues and cell lines. Moreover, our biodistribution results in an ESCC xenograft model indicated that ITGA6 is a possible target for antibody-related diagnostic and therapeutic modalities in ESCC. Thus, our findings suggest that ITGA6 plays an important role in tumorigenesis in ESCC and represents a potential therapeutic target in the treatment of ESCC.

Lapatinib inhibits the growth of esophageal squamous cell carcinoma and synergistically interacts with 5-fluorouracil in patient-derived xenograft models

Lapatinib is a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and human EGFR-2 (HER2) tyrosine kinase domains. To explore the potential utility of lapatinib for the treatment of esophageal squamous cell carcinoma (ESCC), we examined the expression profiles of EGFR and HER2 in tumor tissues and in paired adjacent non-neoplastic tissues from patients with ESCC. We evaluated the antitumor effects of lapatinib alone or in combination with oxaliplatin or 5-fluorouracil (5-FU) on a panel of primary ESCC cells invitro with various levels of EGFR and HER2 expression. The invivo effect of lapatinib alone or in combination with oxaliplatin or 5-FU was evaluated using a primary ESCC xenograft model. EGFR was overexpressed in 80.9% (76/94) of the ESCC samples, while 24.5% (23/94) of the samples overexpressed HER2. EGFR and HER2 co-overexpression was detected in 22.3% of samples (21/94). In vitro, the primary ESCC cells were more sensitive to lapatinib combined with 5-FU or oxaliplatin than to lapatinib alone. Lapatinib in combination with 5-FU had more potent antitumor effects in the primary ESCC xenograft model, and markedly reduced the phosphorylation of EGFR and HER2, compared with lapatinib alone or in combination with oxaliplatin. These data indicate that lapatinib has activity in EGFR- and/or HER2-expressing ESCC primary cells, and that lapatinib in combination with 5-FU may be a promising treatment strategy for patients with ESCC.

Curcumin potentiates the antitumor effects of 5-FU in treatment of esophageal squamous carcinoma cells through downregulating the activation of NF-κB signaling pathway <italic>in vitro</italic> and <italic>in vivo</italic>

Although constitutive activation of nuclear factor-kappaB (NF-κB) signaling pathway has been reported in multiple different human tumors, the role of NF-κB pathway in esophageal squamous cell carcinoma (ESCC) remains ill-defined. Abundant sources have provided interesting insights into the multiple mechanisms by which curcumin may mediate chemotherapy and chemopreventive effects on cancer. In this study, we first analyzed the status of NF-κB pathway in the two ESCC cell lines Eca109 and EC9706, and then further investigated whether curcumin alone or in combination with 5-fluorouracil (5-FU) could modulate NF-κB pathway in vitro and in vivo. The results showed that NF-κB signaling pathway was constitutively activated in the ESCC cell lines. Curcumin suppressed the activation of NF-κB via the inhibition of IκBα phosphorylation, and downregulated the expressions of Bcl-2 and CyclinD1 in ESCC cell lines. Curcumin combined with 5-FU led to the lower cell viability and higher apoptosis than 5-FU treated alone. In a human ESCC xenograft model, curcumin or 5-FU alone reduced the tumor volume, but their combination had the strongest anticancer effects. Besides, curcumin could also inhibit NF-κB signaling pathway through downregulation of the IκBα phosphorylation and induction of cell apoptosis in vivo. Overall, our results indicated that constitutively activated NF-κB signaling pathway exists in the two ESCC cells and the chemopreventive effects of curcumin were associated with downregulation of NF-κB signaling pathway and its downstream genes.

Comparison of the effect of p65 siRNA and curcumin in promoting apoptosis in esophageal squamous cell carcinoma cells and in nude mice

The activation of the NF-κB signaling pathway plays a critical role in carcinogenesis. The role of the NF-κB pathway in esophageal squamous cell carcinoma (ESCC) remains ill-defined. The objective was to detect whether p65siRNA and curcumin could promote ESCC cell apoptosis and increase the sensitivity of ESCC cells to chemotherapeutic drugs by inhibiting the NF-κB signaling pathway, and to compared these two treatments. In the present study, the status of the NF-κB pathway, in the two ESCC cell lines Eca109 and EC9706, was analyzed and the ability of p65 siRNA and curcumin alone or in combination with 5-FU to modulate this pathway in vitro and in vivo was investigated. The results showed that the NF-κB signaling pathway in the ESCC cell lines was constitutively activated. Both p65 siRNA and curcumin mediated suppression of activation of the NF-κB signaling pathway via inhibition of the expression of p65 or IκBα phosphorylation in ESCC cell lines. The cells treated with combination of p65 siRNA or curcumin and 5-FU revealed a lower cell viability and higher apoptosis compared to those treated with 5-FU alone. In a human ESCC xenograft model, p65 siRNA or curcumin and 5-FU alone reduced the tumor volume, respectively, but their combination had the strongest anticancer effects. Curcumin was more effective than p65 siRNA in vitro and in vivo. Overall, our results indicate that the constitutively activated NF-κB signaling pathway plays a crucial role in these two ESCC cell lines and both p65siRNA and curcumin can promote ESCC cell apoptosis and enhance the sensitivity to 5-FU through suppression of the NF-κB signaling pathway. It is still a long time before RNA interference will be used in the clinic. Therefore, curcumin is proved to be useful in the treatment of ESCC as it is a pharmacologically safe compound without side effects.