Synergistic anti-cancer effect of pristimerin and docetaxel on human colorectal HCT-116 cells

Cancer is one of the significant causes of mortality worldwide. Studies on antineoplastic drugs focused on natural products have revealed several mechanisms to inhibit cancer cells. Bugnay (Antidesma bunius) leaves showed potentials due to its activity observed against brine shrimp and breast cancer cells. However, there is still limited knowledge about its activity against other human cancer cells. This study focused on determining the phytochemical compounds in A. bunius leaves extract, the free radical scavenging activity of the extract using the Diphenylpicrylhydrazyl (DPPH) method, and in vitro cytotoxic activity against two cancer cell lines, namely HCT-116 human colorectal and A549 human lung adenocarcinoma cancer cell lines by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The phytochemicals identified were unsaturated lactones, flavonoids, phenolics, diterpenes, saponins, tannins, carbohydrates, and reducing sugars. The extract showed significant free radical scavenging activity and a direct correlation of activity with concentration levels. It also exhibited cytotoxic activity against HCT-116 human colorectal and A549 human lung adenocarcinoma. Hence, A. bunius leaves have the potential to be a source of antioxidant and antineoplastic compounds. This warrant further isolation of the compounds for chemotherapeutic purposes.Keywords: Antidesma bunius, Bugnay, Cancer, Cytotoxicity, Radical

Panax notoginseng is a commonly used Chinese herb. Although a few studies have found that notoginseng shows anti-tumor effects, the effect of this herb on colorectal cancer cells has not been investigated. 5-Fluorouracil (5-FU) is a chemotherapeutic agent for the treatment of colorectal cancer that interferes with the growth of cancer cells. However, this compound has serious side effects at high doses. In this study, using HCT-116 human colorectal cancer cell line, we investigated the possible synergistic anti-cancer effects between notoginseng flower extract (NGF) and 5-FU on colon cancer cells. The anti-proliferation activity of these modes of treatment was evaluated by MTS cell proliferation assay. Apoptotic effects were analyzed by using Hoechst 33258 staining and Annexin-V/PI staining assays. The anti-proliferation effects of four major single compounds from NGF, ginsenosides Rb1, Rb3, Rc and Rg3 were also analyzed. Both 5-FU and NGF inhibited proliferation of HCT-116 cells. With increasing doses of 5-FU, the anti-proliferation effect was slowly increased. The combined usage of 5-FU 5 microM and NGF 0.25 mg/ml, significantly increased the anti-proliferation effect (59.4 +/- 3.3%) compared with using the two medicines separately (5-FU 5 microM, 31.1 +/- 0.4%; NGF 0.25 mg/ml, 25.3 +/- 3.6%). Apoptotic analysis showed that at this concentration, 5-FU did not exert an apoptotic effect, while apoptotic cells induced by NGF were observed, suggesting that the anti-proliferation target(s) of NGF may be different from that of 5-FU, which is known to inhibit thymidilate synthase. This study demonstrates that NGF can enhance the anti-proliferation effect of 5-FU on HCT-116 human colorectal cancer cells and may decrease the dosage of 5-FU needed for colorectal cancer treatment.

Imatinib (IM) is a pharmaceutical drug that inhibits tyrosine kinase enzymes that are responsible for the activation of many proteins by signal transduction cascades as c-Abl, c-Kit and the platelet-derived growth factor (PDGF) receptor. Thymoquinone (TQ) is an active constituent of Nigella sativa seeds. Thymoquinone benefits are attributed to its medicinal uses as antioxidant, anticancer and antimicrobial agent. This study aimed to investigate the impact of using TQ with IM in the HCT116 human colorectal cancer cell line model. The HCT116 cells were treated with IM or/and TQ in non-constant ratios, in which the fixed concentrations of TQ (5, 10 or 20µmol/L) were co-treated with various concentrations of IM (7.5-120µmol/L) for 24, 48 and 72hours. Imatinib-TQ interaction was analysed using CompuSyn software. The IC50 values for IM were 105, 72μmol/L after 48 and 72hours, respectively, and were significantly reduced to 7.3, 7 and 5.5μmol/L after combination with TQ (10μmol/L) and to 5.8, 5.6 and 4.6μmol/L after combination with TQ (20μmol/L) to 24, 48 and 72hours, respectively. The combination index (CI) and dose reduction index (DRI) values indicate a significant synergism in HCT-116 cells at different treatment time points. Thymoquinone significantly enhances the cellular uptake of IM in HCT116 cells in a time and concentration-dependent manner. A significant downregulation in ATP-binding cassette (ABC) subfamily B member 1 (ABCB1), ABC subfamily G member 2 (ABCG2) and human organic cation transporter 1 (hOCT1) genes was observed in the cells exposed to IM+TQ combination as compared to IM alone, which resulted in a substantial elevation in uptake/efflux ratio in combination group. In conclusion, TQ potentiates IM efficacy on HCT116 cells via uptake/efflux genes modulation.

BackgroundIn an effort to achieve better cancer therapies, we elucidated the combination cancer therapy of STI571 (an inhibitor of Bcr-Abl and clinically used for chronic myelogenous leukemia) and TNF-related apoptosis-inducing ligand (TRAIL, a developing antitumor agent) in leukemia, colon, and prostate cancer cells.MethodsColon cancer (HCT116, SW480), prostate cancer (PC3, LNCaP) and leukemia (K562) cells were treated with STI571 and TRAIL. Cell viability was determined by MTT assay and sub-G1 appearance. Protein expression and kinase phosphorylation were determined by Western blotting. c-Abl and p73 activities were inhibited by target-specific small interfering (si)RNA. In vitro kinase assay of c-Abl was conducted using CRK as a substrate.ResultsWe found that STI571 exerts opposite effects on the antitumor activity of TRAIL. It enhanced cytotoxicity in TRAIL-treated K562 leukemia cells and reduced TRAIL-induced apoptosis in HCT116 and SW480 colon cancer cells, while having no effect on PC3 and LNCaP cells. In colon and prostate cancer cells, TRAIL caused c-Abl cleavage to the active form via a caspase pathway. Interestingly, JNK and p38 MAPK inhibitors effectively blocked TRAIL-induced toxicity in the colon, but not in prostate cancer cells. Next, we found that STI571 could attenuate TRAIL-induced c-Abl, JNK and p38 activation in HCT116 cells. In addition, siRNA targeting knockdown of c-Abl and p73 also reduced TRAIL-induced cytotoxicity, rendering HCT116 cells less responsive to stress kinase activation, and masking the cytoprotective effect of STI571.ConclusionsAll together we demonstrate a novel mediator role of p73 in activating the stress kinases p38 and JNK in the classical apoptotic pathway of TRAIL. TRAIL via caspase-dependent action can sequentially activate c-Abl, p73, and stress kinases, which contribute to apoptosis in colon cancer cells. Through the inhibition of c-Abl-mediated apoptotic p73 signaling, STI571 reduces the antitumor activity of TRAIL in colon cancer cells. Our results raise additional concerns when developing combination cancer therapy with TRAIL and STI571 in the future.

One of the world’s main causes of cancer-related fatalities worldwide is colorectal cancer. The adherent epithelial cells known as HCT116 (human colorectal carcinoma) are frequently employed to examine inflammatory responses in colonic epithelial cells. They are derived from the human colorectal cancer cell line. Crocin, a potent antioxidant, anticarcinogenic was tested in this study to see how it affected the HCT-116 human colorectal cancer cell line. MTT analysis was used to assess cell viability. Crocin's antiproliferative activity to inhibit the proliferation of HCT 116 cancer cells was examined. Crocin displayed the outstanding activities for MTT test, IC50= 10.57 μL/mL for 24 hours was calculated as IC50= 3.29 μL/mL for 48 hours on HCT 116 cell line. Total antioxidant status (TAS) and total oxidant status (TOS) in the prepared cell lysate were determined by using commercial kits. Crocin is thought to be a high potential agent to be used in treatment.

Irinotecan (IRN), a topoisomerase I inhibitor and pro-drug of SN-38, is first-line treatment of colon cancer as part of FOLFIRI and FOLFOXIRI combination chemotherapy. However, IRN causes dose-limiting adverse events such as neutropenia and diarrhea. Dose reductions are sometimes required, which reduce efficacy. Recombinant methioninase (rMETase) targets the fundamental basis of cancer, methionine addiction, known as the Hoffman effect, and enhances the efficacy of numerous chemotherapy drugs. The present study determined the efficacy of rMETase when administered in combination with IRN. Cell viability was assessed by cultivating the HCT-116 human colorectal cancer cell line in 96-well plates at 1×103 cells per well in Dulbecco's modified Eagle's medium (DMEM). Subsequently, HCT-116 cells were treated with increasing concentrations of SN-38, the active form of IRN, ranging from 0.5 nM to 32 nM, and/or rMETase ranging from 0.125 to 8 U/ml. After treatment for 72 h, the half-maximal inhibitory concentration (IC50) of SN-38 alone and rMETase alone for HCT-116 cells were determined. Using the IC50 concentration of rMETase, we determined the IC50 of SN-38 in combination with rMETase. Cell viability was determined with the cell-counting Kit-8 with the WST-8 reagent.. The IC50 of rMETase alone for the HCT-116 cells was 0.55 U/ml, and the IC50 of IRN (SN-38) alone was 3.50 nM. rMETase at 0.55 U/ml lowered the IC50 of SN-38 to 0.232 nM (p<0.0001), a 15-fold reduction. rMETase and IRN are strongly synergistic, giving rise to the possibility of lowering the effective dose of IRN for the treatment of patients with colon cancer, thereby reducing its severe toxicity. This new strategy will allow more patients with cancer to be effectively treated with IRN.

We examined the anticancer effects of a novel sirtuin inhibitor, MHY2256, on HCT116 human colorectal cancer cells to investigate its underlying molecular mechanisms. MHY2256 significantly suppressed the activity of sirtuin 1 and expression levels of sirtuin 1/2 and stimulated acetylation of forkhead box O1, which is a target protein of sirtuin 1. Treatment with MHY2256 inhibited the growth of the HCT116 (TP53 wild-type), HT-29 (TP53 mutant), and DLD-1 (TP53 mutant) human colorectal cancer cell lines. In addition, MHY2256 induced G0/G1 phase arrest of the cell cycle progression, which was accompanied by the reduction of cyclin D1 and cyclin E and the decrease of cyclin-dependent kinase 2, cyclin-dependent kinase 4, cyclin-dependent kinase 6, phosphorylated retinoblastoma protein, and E2F transcription factor 1. Apoptosis induction was shown by DNA fragmentation and increase in late apoptosis, which were detected using flow cytometric analysis. MHY2256 downregulated expression levels of procaspase-8, -9, and -3 and led to subsequent poly(ADP-ribose) polymerase cleavage. MHY2256-induced apoptosis was involved in the activation of caspase-8, -9, and -3 and was prevented by pretreatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, the autophagic effects of MHY2256 were observed as cytoplasmic vacuolation, green fluorescent protein-light-chain 3 punctate dots, accumulation of acidic vesicular organelles, and upregulated expression level of light-chain 3-II. Taken together, these results suggest that MHY2256 could be a potential novel sirtuin inhibitor for the chemoprevention or treatment of colorectal cancer or both.

DNA damage results in transcriptional induction of p53 target genes, including the cyclin-dependent kinase (CDK) inhibitor p21(Cip1) (CDKN1A) and the proapoptotic Bcl-2 family member p53 up-regulated modulator of apoptosis (PUMA). Depending on the cellular context, p21(Cip1) and PUMA mediate cell cycle arrest and apoptosis, respectively. By imposing cell cycle arrest at the expense of apoptosis, p21(Cip1) can sharply reduce the effectiveness of DNA-damaging anticancer agents in colorectal cancer cells. We investigated the link between cell cycle progression and the onset of apoptosis in DNA-damaged cells by analyzing the activation of the apoptotic cascade in p21(Cip1)-deficient HCT116 colorectal cancer cells. DNA damage induced a similar level of p53 activation and PUMA induction in p21(Cip1)-deficient cells compared with wild-type isogenic counterparts. p21(Cip1) did not act as a direct blocker of PUMA. However, only p21(Cip1)-deficient cells showed extensive cytochrome c release, mitochondrial membrane depolarization, and caspase activation. An increase in caspase activation occurred as these cells reached M-phase and incurred polyploidy. When ectopically expressed in p21(Cip1)-deficient HCT116 cells, p21(Cip1), its family member p27(Kip1), and the structurally unrelated CDK inhibitor p16(Ink4a) were similarly effective at causing cell cycle arrest and inhibiting DNA damage-induced apoptotic events such as cytochrome c release, mitochondrial membrane depolarization, and activation of the caspase cascade. These observations suggest that by blocking dysregulated cell cycle progression, CDK inhibitors can influence the sensitivity of the mitochondria to proapoptotic signals in DNA damage-induced cancer cells.

Colorectal cancer (CRC) is one of the leading causes of cancer mortality and 5-Fluorouracil (5-FU) is the most common chemotherapy agent of CRC. A high level of X-ray repair cross complementing group 1 (XRCC1) in cancer cells has been associated with the drug resistance occurrence. Moreover, the activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) has been indicated to regulate the cancer cell survival. Thus, this study was aimed to examine whether XRCC1 plays a role in the 5-FU/AMPK agonist (AICAR)-induced cytotoxic effect on CRC and the underlying mechanisms. Human HCT-116 colorectal cells were used in this study. It was shown that 5-FU increases the XRCC1 expression in HCT-116 cells and then affects the cell survival through CXCR4/Akt signaling. Moreover, 5-FU combined with AICAR further result in more survival inhibition in HCT-116 cells, accompanied with reduced CXCR4/Akt signaling activity and XRCC1 expression. These results elucidate the role and mechanism of XRCC1 in the drug resistance of HCT-116 cells to 5-FU. We also demonstrate the synergistic inhibitory effect of AMPK on 5-FU-inhibited HCT-116 cell survival under the 5-FU and AICAR co-treatment. Thus, our findings may provide a new notion for the future drug regimen incorporating 5-FU and AMPK agonists for the CRC treatment.

OP17 Cystathionine-β-synthase (CBS) is upregulated in colorectal cancer cells and promotes their proliferation

Rationale and Objectives: Cancer accounts for a huge global health burden and is the third highest cause of death across the globe. Cancer cells are known to have higher basal reactive oxygen species (ROS) levels, owing to their higher metabolism and proliferation. Higher basal ROS in cancer cells made them susceptible to exogenous ROS stimuli that lead to cell death. Therefore, in the present study, we have analyzed the effects of Azathioprine, a glutathione (GSH) inhibitor and an intracellular ROS producer. The effect of Azathioprine was analyzed alone or in combination with a BCL-2 family protein inhibitor Z36, on human colorectal cancer cell lines HCT-116 and HCT-15. Methods: The effects of the drugs have been investigated using various methods including cell viability assay, DNA fragmentation assay, and Annexin V-FITC/PI apoptosis assay. In addition, morphological changes evident in cell death were detected by Giemsa staining. Combination dosage for drug synergistic effects was computed through the use of CompuSyn software. Western blot was performed to detect changes in the expression of cell death-related proteins following drug treatments. Results and conclusion: Azathioprine at a dose of 5 µM has been demonstrated to induce cell death in both HCT116 and HCT15 cells in a concentration and time-dependent manner. On the contrary, Z36, a novel BCLXL inhibitor, has demonstrated similar cell viability results at an even lower dose of 2.5 µM. When both drugs were combined at lower doses, no significant effects were observed on the cell viability of either cell line, demonstrating that the combined treatment has no synergistic or additive effects. This suggests that both drugs do not augment each other and might induce cell death via upregulation of ROS using a similar mechanism. Citation Format: Yousuf Tahir Ali, Mahwish Fatima, Muhammad Areeb Ahmed, Hasan Salman Siddiqi, Azhar Hussain, Mati Ur Rehman. Azathioprine and Z36 induced cell death in human colorectal cancer HCT-116 and HCT-15 cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4715.

Chamaecyparis obtusa (CO) belongs to the Cupressaceae family, and it is found widely distributed in Japan and Korea. In this study, the anti-proliferative activities of the methanol and water extracts of CO leaves against a human colorectal cancer cell line (HCT116) were investigated. The methanol extract of CO leaves, at a concentration of 1.25 µg/mL, exhibited anti-proliferative activity against HCT116 cells, while displaying no cytotoxicity against Chang liver cells. Comparative global metabolite profiling was performed using gas chromatography-mass spectrometry coupled with multivariate statistical analysis, and it was revealed that anthricin was the major compound contributing to the anti-proliferative activity. The activation of c-Jun N-terminal kinases played a key role in the apoptotic effect of the methanol extract of CO leaves in HCT116 human colon cancer cells. These results suggest that the methanol extract and anthricin derived from CO leaves might be useful in the development of medicines with anti-colorectal cancer activity.

Pristimerin Inhibits Growth and Induces Apoptosis in Human Colorectal Cancer Cells Through the Generation of Reactive Oxygen Species

ABSTRACTColorectal cancer therapy with 5-fluorouracil (5-Fu) frequently become ineffective due to resistance to this drug; and thus other effective compounds are essential for therapy. It is well-known marine brown seaweeds contain antioxidant compounds the carotenoid fucoxanthin (Fx) and polyphenolic compound phloroglucinol (Ph) which exerted diverse biological activities including antioxidant and anticancer. The aim of this study was to determine the anticancer activities of Fx or Ph alone as well as combination of each chemical with 5-Fu on two human colorectal cancer cell lines (HCT116 and HT29), with comparison to responses in a normal colon cell line (CCD-18Co). Effects of these compounds on cell viability, induction of DNA damage, and cell death were evaluated using MTT assay, comet assay, nuclear condensation assay, and Western blot. 5-Fu decreased cell viability in a concentration-dependent manner in HCT116 and HT29 cells but was not cytotoxic in CCD-18Co cells. 5-Fu induced DNA damage in HCT116 cells with induction of cell death, while no marked effects on DNA damage and cell death were observed in HT29 cells. Fx or Ph alone also reduced cell viability in both cancer cell lines but no apparent cytotoxic effect in CCD-18Co cells, except for Fx at 50 and 100 µM. Diminished cell viability was accompanied by induction of DNA damage (by Fx) and induction of cell death (by Ph). In combination with 5-Fu, Fx at 10 µM (in HCT116 and HT29 cells), and Ph at 300 µM (in HT29 cells) enhanced the cytotoxic effect of 5-Fu; however, no marked cytotoxicity was noted in CCD-18Co cells. Since Fx and Ph alone reduced cancer cell line viability without an effect on normal cells and when in combination enhanced the cytotoxic effect of 5-Fu only in colon cancer cells, these compounds seem promising as anticancer agents.

Objective To evaluate the capability of 18 F-FLT uptake and investigate the early radiation response of human colorectal cancer cells HCT116 exposed to 6 MV X-rays.Methods 3.7 kBq 18F-FLT was added to HCT116 cells with different cell numbers (1.0 × 105-1.5 × 106) and cultured with different times (36,60,84 h).The 18F-FLT uptake rate was measured with a γ-counter after exposed to different does of 6 MV X-rays (0,2,4,6,8 Gy) after 24,48,and 72 h of irradiation.Then the cell uptake inhibition rate,cell proliferation,and cell cycle phase were measured.Results The uptake rate of 18F-FLT in HCT116 was (18.97 ± 1.16)％.The 18F-FLT uptake inhibition rates at 24 h after different does of irradiation (2,4,6,8 Gy) were (32.10±0.02)％,(54.46 ±0.04)％,(62.74 ±0.04)％,and (65.81 ±4.81)％,respectively,which was positively correlated with radiation dose.Conclusions The 18F-FLT uptake rate of human colorectal cancer HCT116 cells could be used to evaluate the early radiation response. Key words: 18F-FLT; Uptake; Colorectal cancer; Radiotherapy