New benzimidazole acridine derivative induces human colon cancer cell apoptosis in vitro via the ROS-JNK signaling pathway

Aim:

To investigate the mechanisms underlying anticancer action of the benzimidazole acridine derivative N-{(1H-benzo[d]imidazol-2-yl)methyl}-2-butylacridin-9-amine(8m) against human colon cancer cells in vitro.

Methods:

Human colon cancer cell lines SW480 and HCT116 were incubated in the presence of 8m, and then the cell proliferation and apoptosis were measured. The expression of apoptotic/signaling genes and proteins was detected using RT-PCR and Western blotting. ROS generation and mitochondrial membrane depolarization were visualized with fluorescence microscopy.

Results:

8m dose-dependently suppressed the proliferation of SW480 and HCT116 cells with IC50 values of 6.77 and 3.33 μmol/L, respectively. 8m induced apoptosis of HCT116 cells, accompanied by down-regulation of Bcl-2, up-regulation of death receptor-5 (DR5), truncation of Bid, cleavage of PARP, and activation of caspases (including caspase-8 and caspase-9 as well as the downstream caspases-3 and caspase-7). Moreover, 8m selectively activated JNK and p38 without affecting ERK in HCT116 cells. Knockout of JNK1, but not p38, attenuated 8m-induced apoptosis. In addition, 8m induced ROS production and mitochondrial membrane depolarization in HCT116 cells. Pretreatment with the antioxidants N-acetyl cysteine or glutathione attenuated 8m-induced apoptosis and JNK activation in HCT116 cells.

Conclusion:

The new benzimidazole acridine derivative, 8m exerts anticancer activity against human colon cancer cells in vitro by inducing both intrinsic and extrinsic apoptosis pathways via the ROS-JNK1 pathway.     

The labdane diterpene sclareol (labd-14-ene-8, 13-diol) induces apoptosis in human tumor cell lines and suppression of tumor growth in vivo via a p53-independent mechanism of action

The labdane diterpene sclareol has demonstrated significant cytotoxicity against human tumor cell lines and human colon cancer xenografts. Therefore, there is need to elucidate the mode of action of this compound as very little information is known for the anticancer activity of sclareol and other labdane diterpenes, in general. COMPARE analysis of GI(50) values for a number of human cancer cell lines was initially implicated in an effort to assign a putative mechanism of action to the compound. Sclareol-induced cell cycle arrest and apoptosis were assessed by flow cytometry and Western blot analyses. Finally, the anticancer ability of sclareol in vivo was assessed by using human colon cancer xenograft/mouse models. Sclareol arrested in vitro the growth of p53-deficient (HCT116(p53-/-)) human colon cancer cells and subsequently induced apoptosis by activating both caspases-8 and -9. Intraperitoneal administration of liposome-encapsulated sclareol at the maximum tolerated dose induced a marked growth suppression of HCT116(p53-/-) tumors established as xenografts in immunodeficient NOD/SCID mice. In conclusion, we demonstrate herein that sclareol kills human tumor cells by inducing arrest at the G(1)-phase of the cell cycle followed by apoptosis that involves activation of caspases-8, -9 and -3 via a p53-independent mechanism. These findings suggest that liposome-encapsulated sclareol possesses chemotherapeutic potential for the treatment of colorectal and other types of human cancer regardless of the p53-status.     

Synthesis, structure, anticancer, and antioxidant activity of para-xylyl linked bis-benzimidazolium salts and respective dinuclear Ag(I) N-heterocyclic carbene complexes (Part-II)

The article describes synthesis, characterization (NMR, FT-IR, microanalysis, X-ray crystallography), in vitro anticancer, and antioxidant activity of para-xylyl linked bis-benzimidazolium salts and respective dinuclear Ag–NHC complexes. All the compounds were tested for their cytotoxicity against human colorectal cancer cells (HCT 116) and DPPH antioxidant evaluation. According to cell viability measurements using MTT assay, all the tested compounds showed dose-dependent cytotoxic activity against HCT 116 cells. The tested compounds demonstrated significant activity with IC₅₀ values range 0.29–3.30 μM for HCT 116 and % age inhibition 6.37–21.00 for DPPH antioxidant study. 5-Fluorouracil was used as standard drug (IC₅₀ 19.2 μM for HCT 116) whereas for DPPH analysis, Gallic acid was used as positive control (% age inhibition 77.68). All the compounds showed potential anticancer activity against human colorectal cancer whereas antioxidant activity was not significant. We found that as the size of N-alkyl substitution on benzimidazolium salt increases its cytotoxicity against cancer decreases whereas a reverse occurs in case of respective complexes.     

Octahedral Pt(IV) complex K101 induces apoptosis via ERK1/2 activation and the p53 pathway in human colon cancer cells

Recently, the synthesized octahedral Pt(IV) compound trans,cis-Pt(acetato)2Cl2(1,4-butanediamine), K101, showed potent anti-tumor activity in vitro and in vivo. For the further investigation of K101-induced anti-cancer activity, we tested cytotoxicity against various cancer cell lines and performed the histoculture drug response assay (HDRA) against human colorectal tumor tissues in vitro. We investigated the signaling pathway of K101-induced apoptosis via expression of p53 and ERK1/2 in the human colon cell line HCT116. The cytotoxicity and the three-dimensional HDRA of K101 were evaluated using the MTT assay. To study the K101-induced apoptosis pathway, we performed FACS analysis and immunoblotting of p53, p21, Bax, Fas and ERK1/2 in HCT116 cells treated with or without K101. The cytotoxic IC50 values of K101 ranged from 1.15 to 2.38 micromol/l, compared to cisplatin ranging from 2.13 to 13.1 micromol/l. Among several cancer cell lines, K101 showed greater potency than cisplatin in colon cancer cell lines. In the HDRA, K101 showed 80.0-91.4% efficacy rates compared with 48.6% for cisplatin against colorectal cancer patient tissues. In the signaling pathway, the expression of p53 and phospho-ERK1/2 was increased in a time-dependent manner by treatment with K101 in the HCT116 cells. When K101 was treated with MEK inhibitor U0126, the cell death rate was increased. The octahedral Pt(IV) complex K101 could be an attractive candidate as a chemotherapeutic agent against colon cancer. ERK1/2 activation and the p53 pathway may play significant functions in mediating K101-induced apoptosis in human colon cancer cells.     

Activated kRas protects colon cancer cells from cucurbitacin-induced apoptosis: the role of p53 and p21

Cucurbitacins have been shown to inhibit proliferation in a variety of cancer cell lines. The aim of this study was to determine their biological activity in colon cancer cell lines that do not harbor activated STAT3, the key target of cucurbitacin. In order to establish the role of activated kRas in the responsiveness of cells to cucurbitacins, we performed experiments in isogenic colon cancer cell lines, HCT116 and Hke-3, which differ only by the presence of an activated kRas allele. We compared the activity of 23, 24-dihydrocucurbitacin B (DHCB) and cucurbitacin R (CCR), two cucurbitacins that we recently isolated, with cucurbitacin I (CCI), a cucurbitacin with established antitumorigenic activity. We showed that cucurbitacins induced dramatic changes in the cytoskeleton (collapse of actin and bundling of tubulin microfilaments), inhibited proliferation and finally induced apoptosis of both HCT116 and Hke-3 cells. However, the presence of oncogenic kRas significantly decreased the sensitivity of cells to the three cucurbitacins tested, CCR, DHCB and CCI. We confirmed that mutational activation of kRas protects cells from cucurbitacin-induced apoptosis using nontransformed intestinal epithelial cells with inducible expression of kRasV12. Cucurbitacins induced the expression of p53 and p21 predominantly in HCT116 cells that harbor mutant Ras. Using HCT116 cells with targeted deletion of p53 or p21 we confirmed that p53 and p21 protect cells from apoptosis induced by cucurbitacins. These results demonstrated that sensitivity of human colon cancer cell lines to cucurbitacins depends on the kRas and p53/p21 status, and established that cucurbitacins can exert antitumorigenic activity in the absence of activated STAT3.     

Synthesis,cytotoxicity, and molecular docking of substituted 3-(2-methylbenzofuran-3-yl)-5-(phenoxymethyl)-1,2,4-oxadiazoles

A series of new benzofuran/oxadiazole hybrids ( 8a – n ) was synthesized from 2H-chromene-3-carbonitriles ( 3a – c ) through the multistep synthetic methodology, and these hybrids are known to exhibit anticancer activities. All the compounds were evaluated for their in vitro cytotoxicity against the HCT116 and MIA PaCa2 cell lines. Compounds 6a (IC₅₀: 9.71 ± 1.9 μM), 6b (IC₅₀: 7.48 ± 0.6 μM), and 6c (IC₅₀: 3.27 ± 1.1 μM) displayed a significant cytotoxic activity, whereas compounds 8d and 8e exhibited good activity against both cell lines. The depletion of glycogen synthase kinase-3β (GSK3β) induces apoptosis through the inhibition of basal NF-κB activity in HCT116 colon cancer cells and MIA PaCa2 pancreatic cancer cells. Molecular docking of compounds 6a , 6b , 6c , 8d , and 8e with GSK3β demonstrated the best binding affinity, correlating with the biological activity assay. Furthermore, the structure–activity relationship of these novel compounds reveals promising features for their use in anticancer therapy.     

Podophyllotoxin Induces ROS-Mediated Apoptosis and Cell Cycle Arrest in Human Colorectal Cancer Cells via p38 MAPK Signaling

Podophyllotoxin (PT), a lignan compound from the roots and rhizomes of Podophyllum peltatum, has diverse pharmacological activities including anticancer effect in several types of cancer. The molecular mechanism of the anticancer effects of PT on colorectal cancer cells has not been reported yet. In this study, we sought to evaluate the anticancer effect of PT on human colorectal cancer HCT116 cells and identify the detailed molecular mechanism. PT inhibited the growth of cells and colony formation in a concentration-dependent manner and induced apoptosis as determined by the annexin V/7-aminoactinomycin D double staining assay. PT-induced apoptosis was accompanied by cell cycle arrest in the G2/M phase and an increase in the generation of reactive oxygen species (ROS). The effects of PT on the induction of ROS and apoptosis were prevented by pretreatment with N-acetyl-L-cysteine (NAC), indicating that an increase in ROS generation mediates the apoptosis of HCT116 cells induced by PT. Furthermore, Western blot analysis showed that PT upregulated the level of phospho (p)-p38 mitogen-activated protein kinase (MAPK). The treatment of SB203580, a p38 inhibitor, strongly prevented the apoptosis induced by PT, suggesting that PT-induced apoptosis involved the p38 MAPK signaling pathway. In addition, PT induced the loss of mitochondrial membrane potential and multi-caspase activation. The results suggested that PT induced cell cycle arrest in the G2/M phase and apoptosis through the p38 MAPK signaling pathway by upregulating ROS in HCT116 cells.     

上调NDRG1表达降低奥沙利铂耐药结肠癌细胞的存活率

目的观察上调NDRG1表达对结肠癌细胞及奥沙利铂耐药结肠癌细胞的毒性作用并探讨其机制。方法以重组真核表达质粒pEGFP-NDRG1-N3转染HCT 116及奥沙利铂耐药的OHP-HCT 116结肠癌细胞,以实时定量(qRT)-PCR法和Western blot法检测转染效率。MTT法检测奥沙利铂对不同结肠癌细胞的毒性及验证OHP-HCT 116细胞的耐药性。给予奥沙利铂干预转染pEGFP-NDRG1-N3的HCT 116细胞及OHP-HCT 116细胞,MTT法检测细胞存活率,流式细胞术检测细胞凋亡率,Western blot法检测凋亡蛋白Bcl-2及p53蛋白水平变化。结果不同浓度奥沙利铂干预下的3株结肠癌细胞中HCT 116细胞对奥沙利铂最敏感,OHP-HCT 116细胞对奥沙利铂耐药得到验证。以不同浓度梯度奥沙利铂干扰转染pEGFP-NDRG1-N3的HCT 116细胞及OHP-HCT 116细胞,与MOCK及siNC组比较,在HCT 116细胞及OHP-HCT 116细胞,转染pEGFP-NDRG1-N3细胞的存活率下降(P<0.05),凋亡率升高(P<0.05),Bcl-2表达降低(P<0.05),p53表达升高(P<0.05)。结论上调NDRG1表达通过调控p53表达改善结肠癌细胞奥沙利铂耐药,提高化疗敏感性。     

Cytotoxic furanogermacranolides from the flowers of Helianthus angustifolius

The dichloromethane extract of the flowers of Helianthus angustifolius L. (Asteraceae, Heliantheae) was investigated in vitro for its cytotoxic activity using human cancer cell lines: CCRF-CEM leukemia, MDA-MB-231 breast cancer, U251 glioblastoma, HCT 116 colon cancer cells, and the human lung fibroblast cell line MRC-5. Cytotoxicity-guided fractionation led to the isolation of four related heliangolide-type sesquiterpene lactones. The structures were elucidated by means of NMR spectroscopy and high-resolution mass spectrometry. Of the investigated compounds, 8-methacrylyl-4,15-iso-atriplicolide (1) showed the highest activity against all tested cancer cell lines with IC?? values ranging from 0.26?±?0.01?μM for CCRF-CEM cells to 4.22?±?0.26?μM for MRC-5 cells.     

Newly synthesized curcumin derivatives: crosstalk between chemico-physical properties and biological activity

New curcumin analogues (ester and acid series) were synthesized with the aim to improve the chemical stability in physiological conditions and potential anticancer activity. Cytotoxicity against different tumorigenic cell lines (human ovarian carcinoma cells -2008, A2780, C13*, and A2780/CP, and human colon carcinoma cells HCT116 and LoVo) was tested to evaluate cellular specificity and activity. Physico-chemical properties such as acidity, lipophilicity, kinetic stability, and free radical scavenging activity were investigated to shed light on the structure-activity relationship and provide new attractive candidates for drug development. Most of ester derivatives show IC(50) values lower than curcumin and exhibit selectivity against colon carcinoma cells. Especially they are extremely active after 24 h exposure showing enhanced inhibitory effect on cell viability. The best performances of ester curcuminoids could be ascribed to their high lipophilicity that favors a greater and faster cellular uptake overcoming their apparently higher instability in physiological condition.     

Cytotoxicity of lissoclibadins and lissoclinotoxins, isolated from a tropical ascidian Lissoclinum cf. badium, against human solid-tumor-derived cell lines

The in vitro growth inhibitory activity of lissoclibadins and lissoclinotoxins isolated from the tropical ascidian Lissoclinum cf. badium against nine human cancer cell lines was examined to evaluate their potential anticancer efficacy. Lissoclibadins 1 (1) and 2 (2), and lissoclinotoxin F (4) showed the strongest activity of the six compounds tested, which were more potent than the anticancer drug cisplatin. Compound 1 has a trimeric structure, and compounds 2 and 4 are structural isomers possessing dimeric structures connected by disulfide and sulfide bonds of trans- and cis-orientations, respectively. Lissoclibadin 3 (3), a dimeric compound connected by two sulfide bonds, and two monomeric compounds (5, 6) were less active than 1, 2, and 4. Lissoclibadin 2 (2) was the most interesting compound possessing potent inhibitory activity against colon (DLD-1 and HCT116), breast (MDA-MB-231), renal (ACHN), and non-small-cell lung (NCI-H460) cancer cell lines and showing no toxicity following a 50 mg/kg single treatment to mice, and preferable stability in rat plasma.     

西红花苷抑制NFATc3活性促进与肿瘤成纤维细胞共培养的结直肠癌细胞放射敏感性

目的 探究西红花苷对与肿瘤成纤维细胞（CAFs）共培养的结直肠癌细胞放射敏感性的影响,并探究分子机制。方法 通过实时荧光定量聚合酶链式反应（qRT-PCR）和蛋白质免疫印记（Western blotting）比较人正常结肠上皮细胞NCM460和结直肠癌细胞系SW480、SW620、HCT116、LOVO中活化T细胞核因子c3（NFATc3）表达差异。建立CAFs与HCT116细胞共培养体系,西红花苷处理细胞后经不同剂量（0、2、4、6、8 Gy）X射线照射,细胞克隆形成实验分析细胞存活分数（SF）。再将HCT116细胞分为对照组、6 Gy组、CAFs/HCT116＋6 Gy组、CAFs/HCT116＋西红花苷＋6 Gy组,进行对应处理后,MTT法检测各处理组HCT116细胞活性,流式细胞术检测各处理组HCT116细胞凋亡率,Hoechst 33258染色观察各处理组HCT116细胞凋亡形态,qRT-PCR和Western blotting测定各处理组HCT116细胞中NFATc3表达水平。结果 相较于人正常结肠上皮细胞NCM460,人结直肠癌细胞系SW480、SW620、HCT116、LOVO中的NFATc3 mRNA和蛋白相对表达量均显著上调（P＜0.05）。与HCT116细胞比较,与CAFs共培养的HCT116细胞经辐射后的SF显著增高（P＜0.05）;与CAFs共培养的HCT116细胞比较,与CAFs共培养的HCT116细胞经西红花苷处理再进行辐射的SF显著降低（P＜0.05）。与6 Gy组比较,CAFs/HCT116＋6 Gy组HCT116细胞存活率显著升高（P＜0.05）,细胞凋亡率显著下降（P＜0.05）,细胞内染色也较为均匀,未见致密浓染的凋亡状细胞,细胞中NFATc3 mRNA和蛋白相对表达量均显著上调（P＜0.05）;而与CAFs/HCT116＋6 Gy组比较,CAFs/HCT116＋西红花苷＋6 Gy组HCT116细胞存活率显著降低（P＜0.05）,细胞凋亡率显著升高（P＜0.05）,细胞中有较多致密浓染、碎裂荧光块,同时,细胞中NFATc3 mRNA和蛋白相对表达量显著下调（P＜0.05）。结论 西红花苷能够明显提高与CAFs共培养的结直肠癌HCT116细胞的放射敏感性,从而促进细胞发生凋亡,该作用可能与抑制NFATc3有关。     

Determination of anticancer potential of a novel pharmacologically active thiosemicarbazone derivative against colorectal cancer cell lines

Thiosemicarbazones have received noteworthy attention due to their numerous pharmacological activities. Various thiosemicarbazone derivatives have been reported to play a key role as potential chemotherapeutic agents for the management of cancer. Herein, we aimed to establish the anticancer efficacy of novel thiosemicarbazone derivative C4 against colon cancer in vitro. The MTT viability assay identified C4 as a promising anticancer compound in a panel of cancer cell lines with the most potent activity against colon cancer cells. Further, anticancer potential of C4 was evaluated against HT-29 and SW620 colon cancer cell lines considering the factors like cell adhesion and migration, oxidative stress, cell cycle arrest, and apoptosis. Our results showed that C4 significantly inhibited the migration and adhesion of colon cancer cells. C4 significantly increased the intracellular reactive oxygen species (ROS) and induced apoptotic cell death. Cell cycle analysis revealed that C4 interfered in the cell cycle distribution and arrested the cells at the G2/M phase of the cell cycle. Consistent with these results C4 also down-regulated the Bcl-XL and Bcl-2 and up-regulated the caspase-3 expression. These findings introduced C4 as the potential anticancer agent against colon cancer.     

LncRNA-MALAT1通过miR-142-3p/TEAD1分子轴调控结直肠癌细胞增殖与凋亡#br#

目的　探讨长链非编码RNA-肺腺癌转移相关转录子1（LncRNA-MALAT1）对结直肠癌细胞增殖与凋亡的影响及相关作用机制。方法　通过Real-time PCR与Western blot实验检测结直肠癌细胞株与人正常结肠上皮细胞中LncRNA-MALAT1、miR-142-3p基因以及TEA结构域转录因子1（TEAD1）蛋白的表达;使用si-MALAT1转染HCT116细胞,在此基础上共转染miR-142-3p inhibitor,利用Real-time PCR与Western blot检测细胞中LncRNA-MALAT1与miR-142-3p基因以及TEAD1、Bax、Bcl-2与Cyclin D1蛋白的表达,通过CCK-8实验检测细胞的增殖水平,通过流式细胞术检测细胞的凋亡水平,通过双荧光素酶实验检测LncRNA-MALAT1与miR-142-3p以及miR-142-3p与TEAD1的结合。结果　与人正常结肠上皮细胞相比,结直肠癌细胞株中LncRNA-MALAT1基因与TEAD1蛋白呈高表达,miR-142-3p基因呈低表达（P＜0.05）;沉默LncRNA-MALAT1能够促进miR-142-3p基因与Bax蛋白表达,抑制LncRNA-MALAT1基因以及Bcl-2、Cyclin D1与TEAD1蛋白表达,抑制细胞增殖,并促进细胞凋亡;在此基础上沉默miR-142-3p能够对上述调控作用实现部分逆转;双荧光素酶实验结果显示,LncRNA-MALAT1与miR-142-3p以及miR-142-3p与TEAD1能够结合。结论　LncRNA-MALAT1能够结合miR-142-3p,促进miR-142-3p靶基因TEAD1表达,进而促进结直肠癌细胞增殖,抑制其细胞凋亡,促进结直肠癌的病理进程。     

Synthesis and anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective Ag(I) N-heterocyclic carbene complexes

The article describes synthesis, characterization (NMR, FT-IR, microanalysis, X-ray crystallography), and in vitro anticancer activity of para-xylyl linked bis-benzimidazolium salts and respective dinuclear Ag–NHC complexes. All the compounds were tested for their cytotoxicity against human colorectal cancer (HCT 116) and promyelocytic leukemia (HL-60) cell lines. According to cell viability measurements using MTT assay, all tested compounds showed dose-dependent cytotoxic activity against both cell lines. The tested compounds demonstrated significant activity with IC₅₀ values range 0.01–18.7 μM for HCT 116 and 0.7–55.7 μM for HL-60 cells. 5-Fluorouracil was used as standard drug (IC₅₀ 19.2 μM for HCT 116 and 5.4 μM for HL-60). We found that as the size of N-alkyl substitution on benzimidazolium salt increases its cytotoxicity decreases whereas a reverse occurred in case of respective complexes.     

Tetrandrine inhibits Wnt/β-catenin signaling and suppresses tumor growth of human colorectal cancer

As one of the most common malignancies, colon cancer is initiated by abnormal activation of the Wnt/β-catenin pathway. Although the treatment options have increased for some patients, overall progress has been modest. Thus, there is a great need to develop new treatments. We have found that bisbenzylisoquinoline alkaloid tetrandrine (TET) exhibits anticancer activity. TET is used as a calcium channel blocker to treat hypertensive and arrhythmic conditions in Chinese medicine. Here, we investigate the molecular basis underlying TET's anticancer activity. We compare TET with six chemotherapy drugs in eight cancer lines and find that TET exhibits comparable anticancer activities with camptothecin, vincristine, paclitaxel, and doxorubicin, and better than that of 5-fluorouracil (5-FU) and carboplatin. TET IC?? is ≤5 μM in most of the tested cancer lines. TET exhibits synergistic anticancer activity with 5-FU and reduces migration and invasion capabilities of HCT116 cells. Furthermore, TET induces apoptosis and inhibits xenograft tumor growth of colon cancer. TET treatment leads to a decrease in β-catenin protein level in xenograft tumors, which is confirmed by T-cell factor/lymphocyte enhancer factor and c-Myc reporter assays. It is noteworthy that HCT116 cells with allelic oncogenic β-catenin deleted are less sensitive to TET-mediated inhibition of proliferation, viability, and xenograft tumor growth. Thus, our findings strongly suggest that the anticancer effect of TET in colon cancer may be at least in part mediated by targeting β-catenin activity. Therefore, TET may be used alone or in combination as an effective anticancer agent.     

A novel synthetic C-1 analogue of 7-deoxypancratistatin induces apoptosis in p53 positive and negative human colorectal cancer cells by targeting the mitochondria: enhancement of activity by tamoxifen

The natural compound pancratistatin (PST), isolated from the Hymenocallis littoralis plant, specifically induces apoptosis in many cancer cell lines. Unlike many other chemotherapeutics, PST is not genotoxic and has minimal adverse effects on non-cancerous cells. However, its availability for preclinical and clinical work is limited due to its low availability in its natural source and difficulties in its chemical synthesis. Several synthetic analogues of 7-deoxypancratistatin with different modifications at C-1 were synthesized and screened for apoptosis inducing activity in human colorectal cancer (CRC) cells. We found that a C-1 acetoxymethyl derivative of 7-deoxypancratistatin, JC-TH-acetate-4 (JCTH-4), was effective in inducing apoptosis in both p53 positive (HCT 116) and p53 negative (HT-29) human CRC cell lines, demonstrating similar efficacy to that of natural PST. JCTH-4 was able to decrease mitochondrial membrane potential (MMP), increase levels of reactive oxygen species in isolated mitochondria, cause release of the apoptogenic factor cytochrome c (Cyto c) from isolated mitochondria, and induce autophagy in HCT 116 and HT-29 cells. Interestingly, when JCTH-4 was administered with tamoxifen (TAM), there was an enhanced effect in apoptosis induction, reactive oxygen species (ROS) production and Cyto c release by isolated mitochondria, and autophagic induction by CRC cells. Minimal toxicity was exhibited by a normal human fetal fibroblast (NFF) and a normal colon fibroblast (CCD-18Co) cell line. Hence, JCTH-4 is a novel compound capable of selectively inducing apoptosis and autophagy in CRC cells alone and in combination with TAM and may serve as a safer and more effective alternative to current cancer therapies.     

Antitumor effect of the angiogenesis inhibitor bevacizumab is dependent on susceptibility of tumors to hypoxia-induced apoptosis

Angiogenesis inhibition has been shown to enhance the therapeutic efficacy of cytotoxic chemotherapy in colorectal cancer. The basis of the contribution of this modality has not been defined fully. To determine the potential role of hypoxia-induced apoptosis, we studied a series of colon cancer cell lines with varying susceptibility to hypoxia. We exposed HT29 and HCT116 colon adenocarcinoma cell lines to sublethal periods of hypoxia three times weekly for 40 exposures, and derived cell lines both more resistant (from HT29) and more sensitive (from HCT116) to hypoxia-induced apoptosis. Both hypoxia-derived cell lines demonstrated more rapid growth than the parental lines when implanted subcutaneously in immunodeficient mice. Treatment of tumor-bearing mice with bevacizumab resulted in depletion of tumor microvasculature, upregulation of Hypoxia-inducible factor-1 alpha (HIF-1alpha), and increased pimonidazole staining, consistent with an anti-angiogenic effect and induction of hypoxia in tumors derived from all cell lines. The proportion of apoptotic cells was increased in all the treated tumors, and was most pronounced in the bevacizumab-treated HCT116-derived cells. The bevacizumab-treated tumors showed growth delay in HT29 and its derivative, and the parental HCT116. In the hypoxia-sensitive HCT116-derived tumors, marked tumor shrinkage and prolonged growth control occurred. Therefore, bevacizumab treatment is an effective inducer of a hypoxic environment, but the resulting cell kill and tumor shrinkage is determined by the susceptibility of the tumor to apoptosis. The induction of apoptosis by hypoxia may contribute to the benefits of such treatment in the clinical setting.