Smac modulates chemosensitivity in head and neck cancer cells through the mitochondrial apoptotic pathway

Curcumin analog, GO-Y078, induces HO-1 transactivation-mediated apoptotic cell death of oral cancer cells by triggering MAPK pathways and AP-1 DNA-binding activity

BACKGROUND

GO-Y078, a new synthetic analogue of curcumin (CUR), has higher oral bioavailability and anticancer activity than CUR, but the oncostatic effect of GO-Y078 on oral squamous cell carcinoma (OSCC) is largely unknown.

RESEARCH DESIGN AND METHODS

In the present study, we examined the oncostatic properties and possible mechanisms of GO-Y078 on human SCC-9 and HSC-3 OSCC cells. Results: Our results indicated that GO-Y078 showed a cytostatic effect against OSCC cells, and this antiproliferative phenomenon stemmed from a mechanism involving multiple levels of cooperation, including cell-cycle G₂/M arrest and apoptosis induction. Mechanistically, GO-Y078 treatment induced caspase-mediated apoptosis via upregulating two apoptosis-modulating proteins, SMAC/DIABLO and heme oxygenase (HO)-1. GO-Y078 transcriptionally induced upregulation of the HO-1 gene by increasing the AP-1 DNA-binding activity, which was initiated by activation of the p38 /JNK1/2 pathways. In the clinic, patients with head and neck cancers expressed lower HO-1 and SMAC/DIABLO levels in primary cancer tissues compared to normal tissues. Clinical datasets also revealed that patients with head and neck cancers expressing high HO-1 had a favorable prognosis. Conclusions: Our results provide new insights into the role of GO-Y078-induced molecular regulation in suppressing OSCC growth and suggest that GO-Y078 has potential therapeutic applications for OSCC.

Potency and Selectivity of SMAC/DIABLO Mimetics in Solid Tumor Therapy

Aiming to promote cancer cell apoptosis is a mainstream strategy of cancer therapy. The second mitochondria-derived activator of caspase (SMAC)/direct inhibitor of apoptosis protein (IAP)-binding protein with low pI (DIABLO) protein is an essential and endogenous antagonist of inhibitor of apoptosis proteins (IAPs). SMAC mimetics (SMs) are a series of synthetically chemical compounds. Via database analysis and literature searching, we summarize the potential mechanisms of endogenous SMAC inefficiency, degradation, mutation, releasing blockage, and depression. We review the development of SMs, as well as preclinical and clinical outcomes of SMs in solid tumor treatment, and we analyze their strengths, weaknesses, opportunities, and threats from our point of view. We also highlight several questions in need of further investigation.

Apoptosis-sensitizing activity of birinapant in head and neck squamous cell carcinoma cell lines

Inhibitor of apoptosis proteins, which are overexpressed in head and neck squamous cell carcinoma (HNSCC), may cause therapeutic resistance. Using SMAC mimetic compounds, including birinapant, to degrade and/or inhibit these proteins and sensitize apoptosis may enhance therapies in HNSCC. Fas expression was analyzed in nine HNSCC cell lines and one keratinocyte cell line via flow cytometry. These cell lines were treated with Fas ligand-Fc (FasL) and birinapant, a bivalent SMAC mimetic, in mono and combination therapies. Cytotoxicity was measured using a crystal violet assay. Annexin V assay was performed for detection of apoptosis. The treatment efficacy of mono and combination therapies was statistically analyzed. Nonlinear regression analysis was performed to determine the inhibitory concentration (IC₁₀) of birinapant. Fas expression was detected in each cell line tested. Mono treatment with FasL revealed minor to no apoptotic effects in the majority of the cell lines. Crystal violet and Annexin V staining revealed increased apoptosis rates for all cell lines following incubation with birinapant in mono treatment. Combination treatment with FasL and birinapant (IC₁₀) revealed additional and synergistic effects in eight out of the ten cell lines. To the best of our knowledge, the present study provided the first evidence of the apoptosis-sensitizing activity of combination treatment with FasL and birinapant in HNSCC cell lines.

MicroRNA-21 inhibits mitochondria-mediated apoptosis in keloid

MicroRNA-21 acts as an oncogene by promoting cell proliferation and migration, whereas inhibiting apoptosis in majority of cancers. MicroRNA-21 is upregulated in human keloid fibroblasts. We hypothesized that microRNA-21 may contribute to pathogenesis of keloid fibroblasts. First, enhanced miR-21 but reduced mitochondrial-mediated apoptosis observed in keloid tissues indicated its importance in keloids development. Second, upregulation of microRNA-21 induced a decrease in the ratio of BAX to BCL-2 and suppressed mitochondrial fission in keloid fibroblasts. Third, by attenuating the decline in cellular mitochondrial membrane potential, overexpression of miR-21 suppressed cytochrome c release to the cytoplasm, followed by a decrease in the activity of intracellular caspase-9 and caspase-3, suggesting that mitochondrial-mediated proapoptotic pathway was impaired. Simultaneously, intracellular reactive oxygen species were decreased, indicating microRNA-21 undermined oxidative stress. This phenotype was reversed by miR-21 inhibition. Therefore, our study demonstrates that inhibition of microRNA-21 induces mitochondrial-mediated apoptosis in keloid fibroblasts, proposing microRNA-21 as a potential therapeutic target in keloid fibroblasts.

HINT2 triggers mitochondrial Ca2+ influx by regulating the mitochondrial Ca2+ uniporter (MCU) complex and enhances gemcitabine apoptotic effect in pancreatic cancer

In early studies, it was shown that HINT2, which sensitizes cells to mitochondrial apoptosis, is down-regulated in hepatocellular carcinoma (HCC) cells (Martin et al., 2006). However, the molecular mechanism of this effect is unknown. Immunohistochemistry revealed that HINT2 expression is relatively low in pancreatic cancer tissues, compared to that in adjacent tissues (P < 0.05). Furthermore, its expression was related to pathological grade and lymph node metastasis (P = 0.0161 and 0.0108, respectively); in addition, down-regulation of HINT2 was found to be associated with relatively poor prognosis in pancreatic cancer patients. Up-regulation of HINT2 was shown to trigger pancreatic cancer cell apoptosis, decrease mitochondrial membrane potential (ΔΨm), promote intracellular reactive oxygen species (ROS) production, and elevate mitochondrial Ca²⁺ levels. However, co-treatment of HINT2 overexpressing BxPC-3 cells with ruthenium red partially inhibited HINT2-induced apoptosis, which was associated with a reduction in ΔΨm and an increase in intracellular ROS and mitochondrial Ca²⁺. According to our results, mitochondrial calcium uptake1 and 2 (MICU1 and MICU2) were down-regulated and the essential MCU regulator (EMRE) was up-regulated in cells transduced with Adv-HINT2. Therefore, we deduced that HINT2 triggers apoptosis in pancreatic cancer cells by regulating mitochondrial Ca²⁺ influx through the mitochondrial calcium uniporter (MCU). In addition, we found that HINT2 can sensitize BxPC-3 and L3.6pl cells to gemcitabine-induced apoptosis and that gemcitabine up-regulates HINT2 expression. This indicates that gemcitabine-induced apoptosis is related to HINT2 levels.

Therapeutic Small Molecules Target Inhibitor of Apoptosis Proteins in Cancers with Deregulation of Extrinsic and Intrinsic Cell Death Pathways

The Cancer Genome Atlas (TCGA) has unveiled genomic deregulation of various components of the extrinsic and intrinsic apoptotic pathways in different types of cancers. Such alterations are particularly common in head and neck squamous cell carcinomas (HNSCC), which frequently display amplification and overexpression of the Fas-associated via death domain (FADD) and inhibitor of apoptosis proteins (IAP) that complex with members of the TNF receptor family. Second mitochondria-derived activator of caspases (SMAC) mimetics, modeled after the endogenous IAP antagonist SMAC, and IAP inhibitors represent important classes of novel small molecules currently in phase I/II clinical trials. Here we review the physiologic roles of IAPs, FADD, and other components involved in cell death, cell survival, and NF-κB signaling pathways in cancers, including HNSCC. We summarize the results of targeting IAPs in preclinical models of HNSCC using SMAC mimetics. Synergistic activity of SMAC mimetics together with death agonists TNFα or TRAIL occurred in vitro, whereas their antitumor effects were augmented when combined with radiation and chemotherapeutic agents that induce TNFα in vivo In addition, clinical trials testing SMAC mimetics as single agents or together with chemo- or radiation therapies in patients with HNSCC and solid tumors are summarized. As we achieve a deeper understanding of the genomic alterations and molecular mechanisms underlying deregulated death and survival pathways in different cancers, the role of SMAC mimetics and IAP inhibitors in cancer treatment will be elucidated. Such developments could enhance precision therapeutics and improve outcomes for cancer patients. Clin Cancer Res; 23(6); 1379-87. ©2016 AACR.

AZD5582, an IAP antagonist that leads to apoptosis in head and neck squamous cell carcinoma cell lines and is eligible for combination with irradiation

CONCLUSION

On the one hand, AZD5582, an inhibitor of inhibitor of apoptosis family proteins (IAP), leads to cellular growth arrest and induction of apoptosis in head and neck squamous cell carcinoma (HNSCC) cell lines. On the other hand, it is a viable candidate for combination therapy with irradiation.

OBJECTIVES

The aim and purpose of this study was to evaluate the effects of AZD5582 on HNSCC cell lines.

METHODS

HNSCC cell lines SCC25, Cal27, and FaDu were used for all cell culture experiments. Proliferation assays were used to assess a potential inhibitory effect of AZD5582 and a combination therapy of the IAP inhibitor and irradiation. Colony forming assays were used to determine long-term effects of a combined treatment. Apoptosis was measured via flow cytometry and wound-healing assays were performed.

RESULTS

All three cell lines showed a dose-dependent cytotoxic effect after treatment with AZD5582. It was possible to observe a synergistic and additive effect after short-term treatment of AZD5582 and irradiation in Ca27 and FaDu cells, respectively. All test cell lines showed a significant inhibition of colony formation after combined treatment. Treatment of AZD5582 resulted in apoptosis in SCC25, Cal27, and FaDu cells.

Compounds From Celastraceae Targeting Cancer Pathways and Their Potential Application in Head and Neck Squamous Cell Carcinoma: A Review

Squamous cell carcinoma of the head and neck is one of the most common cancer types worldwide. It initiates on the epithelial lining of the upper aerodigestive tract, at most instances as a consequence of tobacco and alcohol consumption. Treatment options based on conventional therapies or targeted therapies under development have limited efficacy due to multiple genetic alterations typically found in this cancer type. Natural products derived from plants often possess biological activities that may be valuable in the development of new therapeutic agents for cancer treatment. Several genera from the family Celastraceae have been studied in this context. This review reports studies on chemical constituents isolated from species from the Celastraceae family targeting cancer mechanisms studied to date. These results are then correlated with molecular characteristics of head and neck squamous cell carcinoma in an attempt to identify constituents with potential application in the treatment of this complex disease at the molecular level.

mTOR inhibitors induce apoptosis in colon cancer cells via CHOP-dependent DR5 induction on 4E-BP1 dephosphorylation

The mammalian target of rapamycin (mTOR) is commonly activated in colon cancer. mTOR complex 1 (mTORC1) is a major downstream target of the PI3K/ATK pathway and activates protein synthesis by phosphorylating key regulators of mRNA translation and ribosome synthesis. Rapamycin analogs Everolimus and Temsirolimus are non-ATP-competitive mTORC1 inhibitors, and suppress proliferation and tumor angiogenesis and invasion. We now show that apoptosis plays a key role in their anti-tumor activities in colon cancer cells and xenografts through the DR5, FADD and caspase-8 axis, and is strongly enhanced by TRAIL and 5-fluorouracil. The induction of DR5 by rapalogs is mediated by the ER stress regulator and transcription factor CHOP, but not the tumor suppressor p53, upon rapid and sustained inhibition of 4E-BP1 phosphorylation, and attenuated by eIF4E expression. ATP-competitive mTOR/PI3K inhibitors also promote DR5 induction and FADD-dependent apoptosis in colon cancer cells. These results establish activation of ER stress and the death receptor pathway as a novel anticancer mechanism of mTOR inhibitors.

Differential response of head and neck cancer cell lines to TRAIL or Smac mimetics is associated with the cellular levels and activity of caspase-8 and caspase-10

Background:

Current treatment strategies for head and neck cancer are associated with significant morbidity and up to 50% of patients relapse, highlighting the need for more specific and effective therapeutics. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and Smac mimetics (SMs) are promising anticancer agents, but their effect on head and neck squamous cell carcinoma (HNSCC) remains unknown.

Methods:

We examined the response of a panel of nine HNSCC cell lines to TRAIL and SMs and investigated the mechanism of cell type-specific response by functional analysis.

Results:

Head and neck cancer cell lines revealed a converse response pattern with three cell lines being highly sensitive to Smac-164 (SM) but resistant to TRAIL, whereas the other six were sensitive to TRAIL but resistant to SM. Distinct protein expression and activation patterns were found to be associated with susceptibility of HNSCC cell lines to TRAIL and SM. Tumour necrosis factor-related apoptosis-inducing ligand sensitivity was associated with high caspase-8 and Bid protein levels, and TRAIL-sensitive cell lines were killed via the type II extrinsic apoptotic pathway. Smac mimetic-sensitive cells expressed low levels of caspase-8 and Bid but had high TNF-α expression. Smac mimetic-induced cell death was associated with caspase-10 activation, suggesting that in the absence of caspase-8, caspase-10 mediates response to SM. Cotreatment with TNF-α sensitised the resistant cells to SM, demonstrating a decisive role for TNF-α-driven feedback loop in SM sensitivity.

Conclusions:

Tumour necrosis factor-related apoptosis-inducing ligand and SMs effectively kill HNSCC cell lines and therefore represent potential targeted therapeutics for head and neck cancer. Distinct molecular mechanisms determine the sensitivity to each agent, with levels of TNF-α, caspase-8, Bid and caspase-10 providing important predictive biomarkers of response to these agents.

Clinical significance of Smac and survivin expression in breast cancer patients treated with anthracycline‑based neoadjuvant chemotherapy

The second mitochondria‑derived activator of caspases (Smac), an antagonist of the inhibitor of apoptosis protein (IAP), increases chemosensitivity in vitro. Survivin, an IAP family member, mediates cancer cell survival and chemoresistance. The present study investigated the correlation between Smac and survivin expression in primary breast cancer, and the sensitivity to anthracycline during neoadjuvant chemotherapy (NAC). Pre‑treatment biopsies and post‑anthracycline treatment tumor sections were analyzed from 98 cases. Biomarker expression was evaluated by immunohistochemistry in tumor samples from clinical stage II and III anthracycline‑based NAC‑treated breast cancer. A univariate analysis indicated that the estrogen receptor (ER), Smac and survivin were significantly predictive of a pathological complete response (pCR) (P=0.004, 0.001 and 0.037, respectively) in pre‑chemotherapy samples. ER, Smac and survivin expression was also significant for pCR on the multivariate analysis (P=0.001, 0.031 and 0.012, respectively). An inverse association was identified between survivin and Smac expression (r=‑0.217, P=0.032; and r=‑0.335, P=0.003, respectively) prior to and following NAC. The patients with low survivin expression or high Smac expression had significantly longer disease‑free survival (DFS; P=0.012 and P=0.020, respectively) and overall survival (OS; P=0.01 and P=0.033, respectively) compared with the patients with high survivin or low Smac expression. Cox regression analyses demonstrated that survivin, Smac and clinical stage were independent predictors for DFS and OS. The present study indicated the significance of Smac and survivin in determining the breast cancer response to anthracycline‑based chemotherapy, and may permit further stratifying of pre‑chemotherapy patients to undertake more tailored treatments.

Role of apoptosis in colon cancer biology, therapy, and prevention

Deregulation of apoptosis is a hallmark of human cancer and contributes to therapeutic resistance. Recent advances in cancer genomics reveal a myriad of alterations in key pathways that directly or indirectly increase tumor cell survival. This review will outline the pathways of apoptosis in mammalian cells, and highlight the common alterations of apoptosis regulators found in colon cancer, the role of apoptosis and underlying mechanisms in colon cancer treatment and prevention, including recent advances on investigational agents, such as kinase inhibitors, proteasome inhibitors, HSP90 inhibitors, BH3 mimetics, TRAIL, and IAP antagonists. Topics will also include novel concepts, as well as opportunities and challenges for drug discovery and combination therapy by exploring cancer-specific genetic defects, and therefore selective induction of apoptosis in cancer cells. Although the emphasis is on colon cancer, the main theme and many of the aspects are applicable to other solid tumors.

A Smac mimetic augments the response of urothelial cancer cells to gemcitabine and cisplatin

Cisplatin-based chemotherapy is considered the gold standard for patients with advanced bladder cancer. However, despite initial response, many patients will relapse; therefore, novel salvage treatment strategies are desperately needed. Herein, we studied a mechanism based treatment combination using a Smac mimetic with standard chemotherapy. Using a panel of 10 urothelial cancer cell lines, we exposed them to a combination of gemcitabine, cisplatin, and a Smac mimetic. Sensitivity was determined using a DNA fragmentation assay. We determined that three cell lines (UMUC-3, UMUC-13, and RT4v6) were considered sensitive to the combination of gemcitabine and cisplatin and an additional three cell lines were sensitized to gemcitabine and cisplatin with the addition of the Smac mimetic (UMUC-6, UMUC-12, and UMUC-18). We next explored the constitutive expression of selected members of the IAP family (XIAP, cIAP-1, cIAP-2, and Survivin), the BCL family (BCL-2, BCLXL, and BAX) and Smac using gene expression profiling and western blotting. We determined that RNA and protein expression of SMAC, selected members of the IAP family and members of the BCL family did not correlate to drug sensitivity. Lastly, using an in vivo mouse model, we determined that treatment with the Smac mimetic in combination with gemcitabine and cisplatin resulted in increased apoptosis, decreased microvessel density and decreased cellular proliferation. This novel treatment strategy may be effective in patients with advanced urothelial carcinoma and warrants further investigation.

Clinical outcomes of radiation-based locoregional therapy in locally advanced head and neck squamous cell carcinoma patients not responding to induction chemotherapy

OBJECTIVE

The purpose of this study was to evaluate the efficacy of radiation-based locoregional therapy for locally advanced head and neck squamous cell carcinoma (LA-HNSCC) patients who did not respond to induction chemotherapy (IC).

STUDY DESIGN

Outcomes after radiation-based locoregional therapy were retrospectively analyzed.

RESULTS

Among a total of 208 patients treated with IC, 46 (22.1%) did not respond. After IC, patients were treated with radiotherapy (RT), concurrent chemoradiotherapy (CCRT), or surgery with or without postoperative RT. Among the 46 nonresponders, 17 (37.8%) patients underwent surgery and 28 (62.2%) were treated with RT or CCRT. Responses to subsequent RT or CCRT for 26 evaluable patients were as follows: complete response=7 (26.9%), partial response=9 (34.6%), stable disease=4 (15.4%), and progressive disease=6 (23.1%).

CONCLUSION

A significant proportion of LA-HNSCC patients who did not respond to IC can benefit from subsequent RT or CCRT.

An apoptosis-independent role of SMAC in tumor suppression

Reduced expression of the pro-apoptotic protein SMAC (second mitochondria-derived activator of caspase) has been reported to correlate with cancer progression, while its significance and underlying mechanisms are poorly understood. In this study, we investigated the role of SMAC in intestinal tumorigenesis using both human samples and animal models. Decreased SMAC expression was found to correlate with increased cIAP2 expression and higher grades of human colon cancer. In mice, SMAC deficiency significantly increased the incidence and size of colon tumors induced by azoxymethane (AOM)/dextran sulfate sodium salt (DSS), and highly enriched β-catenin hot spot mutations. SMAC deficiency also significantly increased the incidence of spontaneous intestinal polyps in APC(Min/+) mice. Loss of SMAC in mice led to elevated levels of cIAP1 and cIAP2, increased proliferation and activation of the NF-κB p65 subunit in normal and tumor tissues. Unexpectedly, SMAC deficiency had little effect on the incidence of precursor lesions, or apoptosis induced by AOM or DSS, or in established tumors in mice. Furthermore, SMAC knockout enhanced TNFα-mediated NF-κB activation via cIAP2 in HCT 116 colon cancer cells. These results demonstrate an essential and apoptosis-independent function of SMAC in tumor suppression and provide new insights into the biology and targeting of colon cancer.

The multi-targeted kinase inhibitor sunitinib induces apoptosis in colon cancer cells via PUMA

Constitutive activation of pro-survival kinases has become a promising target of small molecules with an increasing interest in developing multi-targeted agents. The mechanisms underlying the responsiveness to most agents targeting cancer specific survival pathways are still poorly understood but critical for their clinical application. In this study, we found that sunitinib, a small molecule inhibitor of multiple tyrosine kinases including VEGFRs and PDGFRs induces apoptosis and inhibits cell growth in colon cancer cells in cell culture and xenograft models via the BH3-only protein PUMA. Sunitinib treatment induced PUMA transcription via the AKT/FoxO3a axis. PUMA, BH3 mimetics, or 5-Flurourical sensitized colon cancer cells to sunitinib-induced apoptosis. Furthermore, PUMA was induced by sunitinib treatment in xenograft tumors, and deficiency in PUMA significantly suppressed the anti-tumor effects of sunitinib. Our study suggests that PUMA-mediated apoptosis is important for the therapeutic responses to sunitinib, and activation of the mitochondrial pathway by BH3 mimetics or PUMA manipulation may be useful for improving the antitumor activity of sunitinib. Modulation of PUMA and selective Bcl-2 family members might be potential biomarkers for predicting sunitinib responses.

Fas death receptor signalling: roles of Bid and XIAP

Fas (also called CD95 or APO-1), a member of a subgroup of the tumour necrosis factor receptor superfamily that contain an intracellular death domain, can initiate apoptosis signalling and has a critical role in the regulation of the immune system. Fas-induced apoptosis requires recruitment and activation of the initiator caspase, caspase-8 (in humans also caspase-10), within the death-inducing signalling complex. In so-called type 1 cells, proteolytic activation of effector caspases (-3 and -7) by caspase-8 suffices for efficient apoptosis induction. In so-called type 2 cells, however, killing requires amplification of the caspase cascade. This can be achieved through caspase-8-mediated proteolytic activation of the pro-apoptotic Bcl-2 homology domain (BH)3-only protein BH3-interacting domain death agonist (Bid), which then causes mitochondrial outer membrane permeabilisation. This in turn leads to mitochondrial release of apoptogenic proteins, such as cytochrome c and, pertinent for Fas death receptor (DR)-induced apoptosis, Smac/DIABLO (second mitochondria-derived activator of caspase/direct IAP binding protein with low Pi), an antagonist of X-linked inhibitor of apoptosis (XIAP), which imposes a brake on effector caspases. In this review, written in honour of Juerg Tschopp who contributed so much to research on cell death and immunology, we discuss the functions of Bid and XIAP in the control of Fas DR-induced apoptosis signalling, and we speculate on how this knowledge could be exploited to develop novel regimes for treatment of cancer.

Role of Smac in determining the chemotherapeutic response of esophageal squamous cell carcinoma

PURPOSE

Second mitochondria-derived activator of caspase (Smac) regulates chemotherapy-induced apoptosis. Smac mimetics have been tested in clinical trials as chemosensitizers. We determined the role of Smac in modulating the chemosensitivity of esophageal squamous cell carcinoma (ESCC).

EXPERIMENTAL DESIGN

Smac expression was evaluated in tissues from ESCC patients with differential chemotherapeutic responses. The effects of Smac knockdown and Smac mimetics on the chemosensitivity of ESCC cells and the molecular mechanisms by which Smac and Smac mimetics modulate chemosensitivity were determined. The therapeutic responses of ESCC cells with different Smac statuses were compared using xenograft models.

RESULTS

We found that Smac was significantly downregulated in most ESCC samples (36.8%, 25/68, P = 0.001), and Smac expression differed significantly (P < 0.05) between chemosensitive and chemoresistant tumors. The associations of tested factors and their responses were examined using logistic regression analysis. In ESCC cells treated with cisplatin, a common chemotherapeutic drug, Smac and cytochrome c were released from mitochondria, and caspase-3 and caspase-9 were activated. Knockdown of Smac abrogated cisplatin-induced apoptosis, mitochondrial dysfunction, cytochrome c release, and caspase activation. Smac deficiency also reduced the effect of cisplatin on long-term cell viability, and led to cisplatin resistance in xenograft tumors in vivo. LBW242, a small molecule Smac mimetic, enhanced cisplatin-induced apoptosis and caspase activation and restored cisplatin sensitivity in Smac-deficient cells.

CONCLUSION

Our data suggested that downregulation of Smac may be a chemoresistance mechanism in ESCC. Combinations of Smac mimetics with chemotherapeutic agents may have therapeutic benefits for the treatment of esophageal cancer.