Matrine suppresses breast cancer cell proliferation and invasion via VEGF-Akt-NF-<Emphasis Type="Italic">κ</Emphasis>B signaling

Matrine has shown therapeutic and/or adjuvant therapeutic effects on the treatment of some patients with breast cancer. However, its mechanisms of action are largely unknown. To disclose the mechanisms, we investigated in vitro and ex vivo effects of matrine on the cancer cells. Our results confirmed that matrine significantly suppressed the proliferation of highly-metastatic human breast cancer MDA-MB-231 cell line. Matrine displayed synergistic effects with existing anticancer agents celecoxib (the inhibitor of cyclooxygenase-2), trichostatin A (the histone deacetylase inhibitor) and rosiglitazone against the proliferation and VEGF excretions in MDA-MB-231 cells. Matrine induced the apoptosis and cell cycle arrest by reducing the ratios of Bcl-2/Bax protein and mRNA levels in the cancer cells. Matrine significantly reduced the invasion, MMP-9/MMP-2 activation, Akt phosphorylation, nuclear factor κB p-65 expression and DNA binding activity, and mRNA levels of MMP-9, MMP-2, EGF and VEGFR1 in MDA-MB-231 cells. Collectively, our results suggest that matrine inhibits the cancer cell proliferation and invasion via EGF/VEGF-VEGFR1-Akt-NF-κB signaling pathway.     

Matrine Induces Apoptosis in Human Acute Myeloid Leukemia Cells via the Mitochondrial Pathway and Akt Inactivation

Acute myeloid leukemia (AML) is a hematological malignancy characterized by a rapid increase in the number of immature myeloid cells in bone marrow. Despite recent advances in the treatment, AML remains an incurable disease. Matrine, a major component extracted from Sophora flavescens Ait, has been demonstrated to exert anticancer effects on various cancer cell lines. However, the effects of matrine on AML remain largely unknown. Here we investigated its anticancer effects and underlying mechanisms on human AML cells in vitro and in vivo. The results showed that matrine inhibited cell viability and induced cell apoptosis in AML cell lines as well as primary AML cells from patients with AML in a dose- and time-dependent manner. Matrine induced apoptosis by collapsing the mitochondrial membrane potential, inducing cytochrome c release from mitochondria, reducing the ratio of Bcl-2/Bax, increasing activation of caspase-3, and decreasing the levels of p-Akt and p-ERK1/2. The apoptotic effects of matrine on AML cells were partially blocked by a caspase-3 inhibitor Z-DEVD-FMK and a PI3K/Akt activator IGF-1, respectively. Matrine potently inhibited in vivo tumor growth following subcutaneous inoculation of HL-60 cells in SCID mice. These findings indicate that matrine can inhibit cell proliferation and induce apoptosis of AML cells and may be a novel effective candidate as chemotherapeutic agent against AML.     

Matrine promotes liver cancer cell apoptosis by inhibiting mitophagy and PINK1/Parkin pathways

Matrine is a natural alkaloid isolated from the root and stem of the legume plant Sophora. Its anti-proliferative and pro-apoptotic effects on several types of cancer have been well-documented. However, the role of matrine in regulating mitochondrial homeostasis, particularly mitophagy in liver cancer apoptosis, remains uncertain. The aim of our study was to explore whether matrine promotes liver cancer cell apoptosis by modifying mitophagy. HepG2 cells were used in the study and treated with different doses of matrine. Cell viability and apoptosis were determined by MTT assay, TUNEL staining, western blotting, and LDH release assay. Mitophagy was monitored by immunofluorescence assay and western blotting. Mitochondrial function was assessed by immunofluorescence assay, ELISA, and western blotting. The results of our study indicated that matrine treatment dose-dependently reduced cell viability and increased the apoptotic rate of HepG2 cells. Functional studies demonstrated that matrine treatment induced mitochondrial dysfunction and activated mitochondrial apoptosis by inhibiting protective mitophagy. Re-activation of mitophagy abolished the pro-apoptotic effects of matrine on HepG2 cells. Molecular investigations further confirmed that matrine regulated mitophagy via the PINK1/Parkin pathways. Matrine blocked the PINK1/Parkin pathways and repressed mitophagy, whereas activation of the PINK1/Parkin pathways increased mitophagy activity and promoted HepG2 cell survival in the presence of matrine. Together, our data indicated that matrine promoted HepG2 cell apoptosis through a novel mechanism that acted via inhibiting mitophagy and the PINK1/Parkin pathways. This finding provides new insight into the molecular mechanism of matrine for treating liver cancer and offers a potential target to repress liver cancer progression by modulating mitophagy and the PINK1/Parkin pathways.     

Silibinin triggers apoptotic signaling pathways and autophagic survival response in human colon adenocarcinoma cells and their derived metastatic cells

Silibinin, a flavonolignan isolated from the milk thistle plant (Silybum marianum), possesses anti-neoplastic properties. In vitro and in vivo studies have recently shown that silibinin inhibits the growth of colorectal cancer (CRC). The present study investigates the mechanisms of silibinin-induced cell death using an in vitro model of human colon cancer progression, consisting of primary tumor cells (SW480) and their derived metastatic cells (SW620) isolated from a metastasis of the same patient. Silibinin induced apoptotic cell death evidenced by DNA fragmentation and activation of caspase-3 in both cell lines. Silibinin enhanced the expression (protein and mRNA) of TNF-related apoptosis-inducing ligand (TRAIL) death receptors (DR4/DR5) at the cell surface in SW480 cells, and induced their expression in TRAIL-resistant SW620 cells normally not expressing DR4/DR5. Caspase-8 and -10 were activated demonstrating the involvement of the extrinsic apoptotic pathway in silibinin-treated SW480 and SW620 cells. The protein Bid was cleaved in SW480 cells indicating a cross-talk between extrinsic and intrinsic apoptotic pathway. We demonstrated that silibinin activated also the intrinsic apoptotic pathway in both cell lines, including the perturbation of the mitochondrial membrane potential, the release of cytochrome c into the cytosol and the activation of caspase-9. Simultaneously to apoptosis, silibinin triggered an autophagic response. The inhibition of autophagy with a specific inhibitor enhanced cell death, suggesting a cytoprotective function for autophagy in silibinin-treated cells. Taken together, our data show that silibinin initiated in SW480 and SW620 cells an autophagic-mediated survival response overwhelmed by the activation of both the extrinsic and intrinsic apoptotic pathways.     

Annexin A3 depletion overcomes resistance to oxaliplatin in colorectal cancer via the MAPK signaling pathway

Colorectal cancer (CRC) is a common disease with high mortality and morbidity. Annexin A3 (ANXA3) belongs to the structurally homologous family of Ca²⁺ and phospholipid-binding proteins. This study aimed to investigate the effects and potential mechanisms of ANXA3 on oxaliplatin (Ox) resistance in CRC. We generated two human CRC cell lines (HCT116/Ox and SW480/Ox) with acquired Ox resistance and determined their resistance properties. ANXA3 expression and cell apoptosis, migration and invasion also were evaluated. We found that cell viability of HCT116/Ox and SW480/Ox was higher than that in parental cells in the presence of Ox. ANXA3 was highly expressed in HCT116/Ox and SW480/Ox cells. ANXA3 downregulation diminished cell survival, migration and invasion, while increased the apoptosis of HCT116 and SW480 with or without Ox. Moreover, depletion of ANXA3 reduced cell viability and BrdU incorporation, increased cell apoptosis and c-caspase 3 expression in HCT116/Ox with or without Ox. A transwell assay determined that knockdown of ANXA3 impeded the migration and invasion of HCT116/Ox and SW480/Ox cells. Additionally, phosphorylation of extracellular signal–regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) decreased upon ANXA3 depletion in HCT116/Ox cells, and ANXA3 silencing suppressed Ox-induced activation of ERK and JNK signaling pathway. ANXA3 downregulation reduced Ox resistance in CRC, and treatment with the ERK inhibitor PD098059 or JNK inhibitor SP600125 contributed to this process. These results indicate that silencing ANXA3 could overcome Ox resistance in CRC via the mitogen-activated protein kinase signaling pathway.     

Matrine inhibits proliferation and induces apoptosis of human colon cancer LoVo cells by inactivating Akt pathway

The present study has investigated the anti-tumor activity and the underlying mechanisms of matrine on human colon cancer LoVo cells. Matrine inhibited the proliferation of the cells in dose- and time-dependent manners. The concentration required for 50 % inhibition (IC₅₀) was 1.15, 0.738, and 0.414 mg/ml, when cell were incubated with matrine for 24, 48, and 72 h, respectively. Matrine induced cell cycle arrest at G1 phase by downregulating cyclin D1 and upregulating p27 and p21. Matrine induced cell apoptosis by reducing the ratio of Bcl-2/Bax and increasing the activation of caspase-9 in a dose-dependent manner. Matrine displayed its anti-tumor activity by inactivating Akt, the upstream factor of the above proteins. Matrine significantly reduced the protein levels of pAkt, and increased the protein levels of other downstream factors, pBad and pGSK-3β. Specific inhibition of pAkt induced cell apoptosis, and synergized with matrine to inhibit the proliferation of LoVo cells; whereas activation of Akt neutralized the inhibitory effect of matrine on cell proliferation. The present study has demonstrated that matrine inhibits proliferation and induces apoptosis of human colon cancer LoVo cells by inactivating Akt pathway, indicating matrine may be a potential anti-cancer agent for colon cancer.     

MKP1 overexpression reduces TNF-α-induced cardiac injury via suppressing mitochondrial fragmentation and inhibiting the JNK–MIEF1 pathways

Mitochondrial stress has been acknowledged as the pathogenesis for tumor necrosis factor-α (TNF-α)-induced septic cardiomyopathy. Recently, MAP kinase phosphatase 1 (MKP1) downregulation and mitochondrial fragmentation modulate the mitochondrial stress via multiple molecular mechanisms. Thereby, the goal of our current work is to figure out the functional role of mitochondrial fragmentation in TNF-α-induced septic cardiomyopathy. Our results exhibited that MKP1 expression was significantly repressed in hearts treated by TNF-α. Overexpression of MKP1 sustained cardiac function and attenuated cardiomyocytes death in TNF-α-treated hearts. At the molecular levels, decreased MKP1 induced mitochondrial stress, as indicated by mitochondrial calcium overloading, mitochondrial oxidative stress, mitochondrial antioxidant downregulation, mitochondrial membrane potential reduction, mitochondrial bioenergetics suppression, mitochondrial proapoptotic factors liberation, and caspase-9 apoptotic pathway activation. To the end, we illustrated that MKP1-modulated mitochondrial stress via mitochondrial fragmentation; reactivation of mitochondrial fragmentation abolished the protective effect of MKP1 overexpression on mitochondrial function. Further, MKP1 affected mitochondrial division in a mechanism through the JNK–MIEF1 axis. Blockade of JNK pathway abolished the regulatory actions of MKP1 on mitochondrial division. Altogether, our results identify MKP1 as a novel cardioprotective factor in TNF-α-related septic cardiomyopathy via affecting mitochondrial division by the way of JNK–MIEF1 signaling pathway. Therefore, MKP1 expression, mitochondrial fragmentation modification, and JNK–MIEF1 pathway modulation may be considered as potential therapeutic targets for the treatment of cardiac injury induced by sepsis.     

Effects of matrine against the growth of human lung cancer and hepatoma cells as well as lung cancer cell migration

The purpose of this study is to investigate in vitro and ex vivo effects of matrine on the growth of human lung cancer and hepatoma cells and the cancer cell migration as well as the expressions of related proteins in the cancer cells. Matrine significantly inhibited the in vitro and ex vivo growth of human non-small cell lung cancer A549 and hepatoma SMMC-7721 cells. Matrine induced the apoptosis in A549 and SMMC-7721 cells. Western blot analysis indicated that matrine dose-dependently down-regulated the expression of anti-apoptotic protein Bcl-2 and up-regulated the level of pro-apoptotic protein bax, eventually leading the reduction of ratios of Bcl-2/Bax proteins in A549 and SMMC-7721 cells. Furthermore, matrine significantly suppressed the A549 cell migration without reducing the cell viability. In addition, matrine dramatically reduced the secretion of vascular endothelial growth factor A in A549 cells. More importantly, matrine markedly enhanced the anticancer activity of anticancer agent trichostatin A (the histone deacetylase inhibitor) by strongly reducing the viability and/or the ratio of Bcl-2/Bax protein in A549 cells. Our findings suggest that matrine may have the broad therapeutic and/or adjuvant therapeutic application in the treatment of human non-small cell lung cancer and hepatoma.     

Urolithin A induces cell cycle arrest and apoptosis by inhibiting Bcl-2, increasing p53-p21 proteins and reactive oxygen species production in colorectal cancer cells

Colorectal cancer (CRC) is the second most common gastrointestinal cancer globally. Prevention of tumor cell proliferation and metastasis is vital for prolonging patient survival. Polyphenols provide a wide range of health benefits and prevention from cancer. In the gut, urolithins are the major metabolites of polyphenols. The objective of our study was to elucidate the molecular mechanism of the anticancer effect of urolithin A (UA) on colorectal cancer cells. UA was found to inhibit the cell proliferation of CRC cell lines in a dose-dependent and time-dependent manner in HT29, SW480, and SW620 cells. Exposure to UA resulted in cell cycle arrest in a dose-dependent manner along with alteration in the expression of cell cycle–related protein. Treatment of CRC cell lines with UA resulted in the induction of apoptosis. Treatment of HT29, SW480, and SW620 with UA resulted in increased expression of the pro-apoptotic proteins, p53 and p21. Similarly, UA treatment inhibited the anti-apoptotic protein expression of Bcl-2. Moreover, exposure of UA induced cytochrome c release and caspase activation. Furthermore, UA was found to generate reactive oxygen species (ROS) production in CRC cells. These findings indicate that UA possesses anticancer potential and may be used therapeutically for the treatment of CRC.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12192-020-01189-8.     

Hsa_circ_0128846 promotes tumorigenesis of colorectal cancer by sponging hsa‐miR‐1184 and releasing AJUBA and inactivating Hippo/YAP signalling

Hsa_circ_0128846 was found to be the most significantly up‐regulated circRNA in our bioinformatics analysis. However, the role of hsa_circ_0128846 in colorectal cancer has not been explored. We thus aim to explore the influence and mechanism of hsa_circ_0128846 in colorectal cancer by sponging its downstream miRNA target miR‐1184. We collected 40 colorectal cancer patients’ tumour tissues to analyse the expression of hsa_circ_0128846, miR‐1184 and AJUBA using qRT‐PCR and Western blot where needed. Then, we constructed stably transfected SW480 and HCT116 cells to study the influence of hsa_circ_0128846, miR‐1184 and AJUBA on colorectal cancer cell phenotypes. To obtain reliable results, a plethora of experiments including RNA immunoprecipitation assay, flow cytometry, EdU incorporation assay, wound healing migration assay, transwell invasion assay and live imaging of nude mice xenograft assay were performed. The binding relationship between hsa_circ_0128846, miR‐1184 and AJUBA mRNA in colorectal cancer was validated by reported gene assay. In colorectal cancer tissues, circ_0128846 and AJUBA were both significantly up‐regulated, while miR‐1184 was significantly down‐regulated compared with healthy tissues. Meanwhile, hsa_circ_0128846 can absorb miR‐1184 to promote the progression of CRC in vivo and SW480 and HCT116 cell phenotypes in vitro. The knockdown of AJUBA, a downstream target of miR‐1184, reversed the effect of miR‐1184 in CRC cells via enhancing the phosphorylation of the Hippo/YAP signalling pathway proteins MST1, LATS1 and YAP. This study revealed that hsa_circ_0128846 contributed to the development of CRC by decreasing the expression of miR‐1184, thereby increasing AJUBA expression and inactivating Hippo/YAP signalling.     

miR-144 suppresses cell proliferation and migration in colorectal cancer by targeting NRAS

Colorectal cancer (CRC) is a type of malignant cancer that has become particularly prevalent worldwide. It is of crucial importance to CRC treatment that the underlying molecular mechanism of CRC progression is determined. The NRAS gene is an important small G protein that is involved in various biological processes, including cancers. NRAS is an oncogene in many neoplasms but its function and regulation in CRC have seldom been investigated. In this study, it was uncovered that the NRAS protein was significantly upregulated in CRC tissues. According to a bioinformatics prediction, we identified that miR-144 may target NRAS to suppress its expression. In vitro experiments indicated that miR-144 decreased NRAS expression in different CRC cell lines (SW480, LoVo, and Caco2). By inhibiting NRAS, miR-144 repress SW480 cell proliferation and migration. Moreover, miR-144 decelerated the growth of SW480 xenograft tumors in vivo by targeting NRAS. In summary, our results identified a novel miR-144-NRAS axis in CRC that could promote the research and treatment of CRC.     

Melatonin attenuates inflammation-related venous endothelial cells apoptosis through modulating the MST1–MIEF1 pathway

Chronic venous disease (CVD) is a prevalent and potentially debilitating condition that affects millions of individuals. An excessive endothelial inflammatory response is reportedly involved in the development of CVD. In this study, we explored the effect and mechanism of melatonin on venous endothelial damage induced by tumor necrosis factor α (TNF-α). Our data demonstrated that inflammation injury triggered mitochondrial dysfunction, activated reactive oxygen species-related oxidative damage, inhibited mitochondrial potential and ultimately initiated caspase-involved cellular death. Interestingly, melatonin preserved inflammation-attacked mitochondrial performance and thus increased cell survival under TNF-α. Cellular experiments illustrated that inflammation injury promoted the levels of mammalian sterile 20-like kinase 1 (MST1) and mitochondrial elongation factor 1 (MIEF1); active MST1–MIEF1 pathway disturbed mitochondria-related energy production, leading to mitochondria-induced cell damage. Interestingly, melatonin effectively suppressed MST1–MIEF1 axis and thus improved cell survival ratio under TNF-α-mediated inflammation injury. Reactivation of MST1–MIEF1 pathway attenuated melatonin-related endothelial protective actions. Herein, our results illuminate that melatonin is an effective approach to attenuate inflammation-related venous endothelial cell damage through handling the MST1–MIEF1 signaling pathway.     

Role of CSN5/JAB1 in Wnt/β-catenin activation in colorectal cancer cells

CSN5/JAB1 is a critical subunit of the COP9 signalosome (CSN) and is overexpressed in many human cancers, but little is known about the role of CSN5 in colorectal cancer (CRC). To explore the functional role of CSN5 in colorectal tumorigenesis, we applied siRNA technology to silence CSN5 in HeLa, SW480, HCT116, HT29, and CaCo2 cells. CSN5 knock-down led to reduced β-catenin and phospho-bcatenin levels and this was paralleled by reduced CRC cell proliferation and reduced apoptosis rates, whereas the short-term β-catenin protein stability was enhanced by CSN5 knock-down in SW480 cells. Together, these data implicate the CSN in the pathogenesis of CRC via regulation of the Wnt/β-catenin pathway     

TMPyP4-regulated cell proliferation and apoptosis through the Wnt/β-catenin signaling pathway in SW480 cells

Background: The aim of this study was to investigate the potential effects of the 5, 10, 15, 20-tetrakis (1-methylpyridinium-4-yl) porphyrin (TMPyP4) on the proliferation and apoptosis of SW480 cells and the underlying mechanisms by which TMPyP4 exerted its actions. Methods: After treated with different doses of TMPyP4, cell viability was determined by MTT method, the apoptosis was observed by flow cytometry (FCM) and the expression of Wnt, GSK-3β, β-catenin and cyclinD1 was measured by RT-PCR and Western blot analysis. Results: The analysis revealed that TMPyP4 potently suppressed cell viability and induced the apoptosis of SW480 cells in a dose-dependent manner. In addition, the downregulation of Wnt, β-catenin and cyclinD1 expression levels was detected in TMPyP4-treated SW480 cells. However, followed by the block of Wnt signaling pathway using siRNA methods, the effects of TMPyP4 on proliferation and apoptosis of SW480 cells were significantly reduced. Conclusion: It indicates that the TMPyP4-inhibited proliferation and -induced apoptosis in SW480 cells was accompanied by the suppression of Wnt/β-catenin signaling pathway. Therefore, TMPyP4 may represent a potential therapeutic method for the treatment of colon carcinoma.     

Matrine induces Akt/mTOR signalling inhibition‐mediated autophagy and apoptosis in acute myeloid leukaemia cells

Pharmacological modulation of autophagy has been referred to as a promising therapeutic strategy for cancer. Matrine, a main alkaloid extracted from Sophora flavescens Ait, has antitumour activity against acute myelocytic leukaemia (AML). Whether autophagy is involved in antileukaemia activity of matrine remains unobvious. In this study, we demonstrated that matrine inhibited cell viability and colony formation via inducing apoptosis and autophagy in AML cell lines HL‐60, THP‐1 and C1498 as well as primary AML cells. Matrine promoted caspase‐3 and PARP cleavage dose‐dependently. Matrine up‐regulated the level of LC3‐II and down‐regulated the level of SQSTM1/p62 in a dose‐dependent way, indicating that autophagy should be implicated in anti‐AML effect of matrine. Furthermore, the autophagy inhibitor bafilomycin A1 relieved the cytotoxicity of matrine by blocking the autophagic flux, while the autophagy promoter rapamycin enhanced the cytotoxicity of matrine. Additionally, matrine inhibited the phosphorylation of Akt, mTOR and their downstream substrates p70S6K and 4EBP1, which led to the occurrence of autophagy. In vivo study demonstrated that autophagy was involved in antileukaemia effect of matrine in C57BL/6 mice bearing murine AML cell line C1498, and the survival curves showed that mice did benefit from treatment with matrine. Collectively, our findings indicate that matrine exerts antitumour effect through apoptosis and autophagy, and the latter one might be a potential therapeutic strategy for AML.     

Matrine inhibits proliferation and induces apoptosis via BID-mediated mitochondrial pathway in esophageal cancer cells

Matrine, as a member of Sophora family, is an alkaloid found in plants, and produces plethora pharmacological effects, including anti-cancer effects. However, the mechanism involved remains largely unknown. This study is conducted to investigate the anti-cancer mechanisms of matrine in human esophageal cancer in vitro and in vivo. In human esophageal cancer cell Eca-109, matrine significantly decreased the cell viability in a dose-dependent manner, and induced apoptosis as well as cell cycle arrest in G0/G1 phase by up-regulation of P53 and P21. The expression of several apoptosis-related proteins in cells and tumor tissues were evaluated by Western blot analysis. We found that matrine induced cell apoptosis by down-regulation of the ratio of BCL-2/BID and increasing activation of caspase-9. Further studies indicated that matrine induced apoptosis of Eca-109 was through the mitochondria-mediated internal pathway, but not by death receptor-mediated extrinsic apoptotic pathway, which was confirmed by the fact that Bid translocated from the nucleus to mitochondria during the process of the apoptosis induced by matrine. In vivo study found that matrine effectively inhibited the tumor formation of Eca-109 cells in nude mice. Our study suggests that matrine could serve as a potential novel agent from natural products to treat esophageal cancer.     

Differential role of Fas/Fas ligand interactions in cytolysis of primary and metastatic colon carcinoma cell lines by human antigen-specific CD8+ CTL

We have previously identified mutated ras peptides reflecting the glycine to valine substitution at position 12 as HLA-A2-restricted, CD8+ CTL neo-epitopes. CTL lines produced against these peptide epitopes lysed the HLA-A2+ Ag-bearing SW480 primary colon adenocarcinoma cell line, although IFN-gamma treatment of the targets was necessary to achieve efficient cytotoxicity. Here, we compared the lytic phenotype of the SW480 cell line to its metastatic derivative, SW620, as an in vitro paradigm to further characterize the nature of a HLA class I-restricted, Ag-specific CTL response against neoplastic cell lines of primary and metastatic origin. Although both colon carcinoma cell lines were lysed by these Ag-specific CTL following IFN-gamma pretreatment, the mechanisms of lysis were distinct, which reflected differential levels of sensitivity to the Fas pathway. Whereas IFN-gamma pretreatment rendered SW480 cells sensitive to both Fas-dependent and -independent (perforin) pathways, SW620 cells displayed lytic susceptibility to Fas-independent mechanisms only. Moreover, pretreatment of SW480 cells with the anti-colon cancer agent, 5-fluorouracil (5-FU), led to enhanced Fas and ICAM-1 expression and triggered Ag-specific CTL-mediated lysis via Fas- and perforin-based pathways. In contrast, these phenotypic and functional responses were not observed with SW620 cells. Overall, these data suggested that 1) IFN-gamma and 5-FU may enhance the lytic sensitivity of responsive colon carcinoma cells to immune effector mechanisms, including Fas-induced lysis; 2) the malignant phenotype may associate with resistance to Fas-mediated lysis in response to Ag-specific T cell attack; and 3) if Ag-specific CTL possess diverse lytic capabilities, this may overcome, to some extent, the potential "escape" of Fas-resistant carcinoma cells.