Killing Of Colorectal Cancer Cells Research Articles

Abstract 529: Investigating the synergistic effect of milciclib and PD0325901 in colorectal cancer therapy

Abstract Milciclib, characterized as a potent nanomolar inhibitor of multiple cyclin-dependent kinases, has recently emerged as a promising therapeutic agent in cancer treatment, particularly with its additional role as a spliceosome modulator. Our recent studies employing RNA sequencing technology revealed a comprehensive profile of Milciclib-induced transcriptional changes in colorectal cancer cells, identifying several key regulated pathways. In light of these findings, we explored a novel therapeutic strategy: combining Milciclib with specific inhibitors targeting pathways upregulated by Milciclib treatment. This hypothesis is based on the rationale that such a combination could exert a synergistic effect. We have assessed the efficacy of this combinational therapy and found that the combination of Milciclib and PD0325901 greatly potentiates the killing of colorectal cancer cells versus either treatment alone. PD0325901 has been extensively studied for its efficacy in targeting the MEK/ERK signaling pathway, a critical pathway in many cancers, including colorectal cancer. To further characterize the underlying molecular mechanisms contributing to the observed synergistic effect, we applied quantitative proteomic analysis of 8107 proteins in human colorectal cancer cells with the treatment of different doses of Milciclib and PD0325901 administered alone, or in combination. Our results demonstrate 49 proteins were significantly decreased in a dose-dependent manner, and that many of these proteins are key players regulating pathways associated with the cell cycle, apoptosis, gene expression, metabolism, WNT signaling, and the MEK/ERK signaling pathway. The discovery of the down-regulation of these proteins and pathways after treatment provides a molecular basis to elucidate the synergistic mechanism underlying Milciclib and PD0325901 combination therapy. In conclusion, our study establishes the combinatorial use of Milciclib and PD0325901 as a potential breakthrough in the treatment of colorectal cancer, offering a promising prospect for enhancing future patient outcomes. Citation Format: Xinyu Pei, Anh Nguyen, Hannah Neiger, Wenjia Wang, William Bautista, Lily Wang, Alvan Cai, Valerie A. Gerriets, John K. Cusick, Yihui Shi. Investigating the synergistic effect of milciclib and PD0325901 in colorectal cancer therapy [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 529.

β-Adrenergic Receptor Inhibitor and Oncolytic Herpesvirus Combination Therapy Shows Enhanced Antitumoral and Antiangiogenic Effects on Colorectal Cancer.

Oncolytic viruses (OVs) are considered a promising therapeutic alternative for cancer. However, despite the development of novel OVs with improved efficacy and tumor selectivity, their limited efficacy as monotherapeutic agents remains a significant challenge. This study extended our previously observed combination effects of propranolol, a nonselective β-blocker, and the T1012G oncolytic virus into colorectal cancer models. A cell viability assay showed that cotreatment could induce synergistic killing effects on human and murine colorectal cell lines. Moreover, cotreatment caused sustained tumor regression compared with T1012G monotherapy or propranolol monotherapy in human HCT116 and murine MC38 tumor models. The propranolol activity was not via a direct effect on viral replication in vitro or in vivo. Western blotting showed that cotreatment significantly enhanced the expression of cleaved caspase-3 in HCT116 and MC38 cells compared with the propranolol or T1012G alone. In addition, propranolol or T1012G treatment induced a 35.06% ± 0.53% or 35.49% ± 2.68% reduction in VEGF secretion in HUVECs (p < 0.01/p < 0.01). Cotreatment further inhibited VEGF secretion compared with the monotherapies (compared with propranolol treatment: 75.06% ± 1.50% decrease, compared with T1012G treatment: 74.91% ± 0.68%; p＜0.001, p < 0.001). Consistent with the in vitro results, in vivo data showed that cotreatment could reduce Ki67 and enhance cleaved caspase 3 and CD31 expression in human HCT116 and murine MC38 xenografts. In summary, β-blockers could improve the therapeutic potential of OVs by enhancing oncolytic virus-mediated killing of colorectal cancer cells and colorectal tumors.

Nanotechnology in Colorectal Cancer for Precision Diagnosis and Therapy

Colorectal cancer (CRC) is the third most frequently occurring tumor in the human population. CRCs are usually adenocarcinomatous and originate as a polyp on the inner wall of the colon or rectum which may become malignant in the due course of time. Although the therapeutic options of CRC are limited, the early diagnosis of CRC may play an important role in preventive and therapeutic interventions to decrease the mortality rate. The CRC-affected tissues exhibit several molecular markers that may be exploited as the novel strategy to develop newer approaches for the treatment of the disease. Nanotechnology consists of a wide array of innovative and astonishing nanomaterials with both diagnostics and therapeutic potential. Several nanomaterials and nano formulations such as Carbon nanotubes, Dendrimer, Liposomes, Silica Nanoparticles, Gold nanoparticles, Metal-organic frameworks, Core-shell polymeric nano-formulations, Nano-emulsion System, etc can be used to targeted anticancer drug delivery and diagnostic purposes in CRC. The light-sensitive photosensitizer drugs loaded gold and silica nanoparticles can be used to diagnose as well as the killing of CRC cells by the targeted delivery of anticancer drugs to cancer cells. This review is focused on the recent advancement of nanotechnology in the diagnosis and treatment of CRC.

Menin-mediated Repression of Glycolysis in Combination with Autophagy Protects Colon Cancer Against Small-molecule EGFR Inhibitors.

Menin serves both tumor suppressor and promoter roles in a highly tumor-specific manner. In colorectal cancer, menin is overexpressed and plays a critical role in regulating transcription of SKP2, and combined treatment with a menin inhibitor and small-molecule EGFR inhibitor (EGFRi) leads to synergistic killing of colorectal cancer cells. However, the full spectrum of menin function in colorectal cancer remains uncertain. Herein, we demonstrate that menin inhibition increases glycolysis in colorectal cancer cells. This menin inhibitor-induced increase in glycolysis occurs in an mTOR-independent manner and enhances the sensitivity of colorectal cancer cells to EGFRis. In addition, we show that EGFRis induce autophagy in colorectal cancer cells, which is important for cell survival in the setting of combined treatment with an EGFRi and menin inhibitor. Inhibition of autophagy with chloroquine further sensitizes colorectal cancers to treatment with the combination of an EGFRi and menin inhibitor. Together, these findings uncover a novel role for menin in colorectal cancer as a repressor of glycolysis and demonstrate that menin inhibitor-induced increases in glycolysis sensitize colorectal cancer cells to EGFRis. In addition, these findings illustrate the importance of autophagy as a protective mechanism against EGFRis, especially in the presence of menin inhibition. Ultimately, these data open the possibility of using menin-mediated regulation of glycolysis to potentially improve treatment modalities for colorectal cancer.

The preclinical analysis of TW-37 as a potential anti-colorectal cancer cell agent.

TW-37 is a novel, potent and non-peptide Bcl-2 small-molecule inhibitor. Its activity in colorectal cancer (CRC) cells is studied. In both HCT-116 cells and primary human colon cancer cells, treatment with TW-37 at only nM concentration efficiently inhibited cell survival and proliferation. TW-37 also induced caspase-3/9 and apoptosis activation in CRC cells. Feedback autophagy activation was observed in TW-37-treated CRC cells. Reversely pharmacological autophagy inhibition or Beclin-1 knockdown by targeted-shRNA potentiated TW-37-induced apoptosis and killing of CRC cells. In vivo, intravenous injection of TW-37 inhibited HCT-116 tumor growth in mice. TW-37’s anti-tumor activity was further potentiated against Beclin-1-silenced HCT-116 tumors. Together, targeting Bcl-2 family protein by TW-37 efficiently inhibits CRC cell growth in vitro and in vivo. Inhibition of feedback autophagy activation could further sensitize TW-37.

FBW7-Dependent Mcl-1 Degradation Mediates the Anticancer Effect of Hsp90 Inhibitors.

Heat shock protein 90 (Hsp90) is widely overexpressed in cancer cells and necessary for maintenance of malignant phenotypes. Hsp90 inhibition induces tumor cell death through degradation of its client oncoproteins and has shown promises in preclinical studies. However, the mechanism by which Hsp90 inhibitors kill tumor cells is not well-understood. Biomarkers associated with differential sensitivity and resistance to Hsp90 inhibitors remain to be identified. In this study, we found that colorectal cancer cells containing inactivating mutations of FBW7, a tumor suppressor and E3 ubiquitin ligase, are intrinsically insensitive to Hsp90 inhibitors. The insensitive colorectal cancer cells lack degradation of Mcl-1, a prosurvival Bcl-2 family protein. Hsp90 inhibition promotes GSK3β-dependent phosphorylation of Mcl-1, which subsequently binds to FBW7 and undergoes ubiquitination and proteasomal degradation. Specifically blocking Mcl-1 phosphorylation by genetic knock-in abrogates its degradation and renders in vitro and in vivo resistance to Hsp90 inhibitors, which can be overcame by Mcl-1-selective small-molecule inhibitors. Collectively, our findings demonstrate a key role of GSK3β/FBW7-dependent Mcl-1 degradation in killing of colorectal cancer cells by Hsp90 inhibitors and suggest FBW7 mutational status as a biomarker for Hsp90-targeted therapy. Mol Cancer Ther; 16(9); 1979-88. ©2017 AACR.

MnTnBuOE-2-PyP protects normal colorectal fibroblasts from radiation damage and simultaneously enhances radio/chemotherapeutic killing of colorectal cancer cells

Manganese porphyrins have been shown to be potent radioprotectors in a variety of cancer models. However, the mechanism as to how these porphyrins protect normal tissues from radiation damage still remains largely unknown. In the current study, we determine the effects of the manganese porphyrin, MnTnBuOE-2-PyP, on primary colorectal fibroblasts exposed to irradiation. We found that 2 Gy of radiation enhances the fibroblasts' ability to contract a collagen matrix, increases cell size and promotes cellular senesence. Treating fibroblasts with MnTnBuOE-2-PyP significantly inhibited radiation-induced collagen contraction, preserved cell morphology and also inhibited cellular senescence. We further showed that MnTnBuOE-2-PyP enhanced the overall viability of the fibroblasts following exposure to radiation but did not protect colorectal cancer cell viability. Specifically, MnTnBuOE-2-PyP in combination with irradiation, caused a significant decrease in tumor clonogenicity. Since locally advanced rectal cancers are treated with chemoradiation therapy followed by surgery and non-metastatic anal cancers are treated with chemoradiation therapy, we also investigated the effects of MnTnBuOE-2-PyP in combination with radiation, 5-fluorouracil with and without Mitomycin C. We found that MnTnBuOE-2-PyP in combination with Mitomycin C or 5-fluorouracil further enhances those compounds' ability to suppress tumor cell growth. When MnTnBuOE-2-PyP was combined with the two chemotherapeutics and radiation, we observed the greatest reduction in tumor cell growth. Therefore, these studies indicate that MnTnBuOE-2-PyP could be used as a potent radioprotector for normal tissue, while at the same time enhancing radiation and chemotherapy treatment for rectal and anal cancers.

Therapeutic targeting truncated adenomatous polyposis coli (APC) proteins for the selective killing of colorectal cancer cells

The adenomatous polyposis coli (APC) gene is a multifunctional tumor suppressor mutated in over 80% of colorectal cancers (CRC). Mutations in APC are believed to be one of the earliest events that contribute to CRC initiation. APC has been implicated in the negative regulation of the canonical Wnt signaling pathway, cell cycle control, cell migration, differentiation, and apoptosis. However, there remain many unanswered questions about the precise roles of APC in CRC progression. For example, over 90% of APC mutations result in truncated proteins, among which termination mutations at codons 1309 and 1450 occur the most frequently. It is completely unclear why the vast majority of human colon cancers would retain truncated APC proteins unless there was some survival/growth advantage to the emerging tumor. We hypothesized that these truncated APC proteins may actually play a dominant (gain of function) role in the initiation and/or progression of CRC and have conducted experiments to test this idea. Our rationale for these experiments is there are no disease-specific targeted treatments for CRC and therapeutic agents targeting APC truncations could be beneficial. We developed a unique series of telomerase (TERT) and CDK4 immortalized human colonic epithelial cell (HCEC) lines and experimentally made isogenic derivatives by ectopic expression of the most commonly observed APC truncations found in patients. In addition, we made TERT and CDK4 expressing HCECs with TP53 and APC knockdowns as well as ectopic expression of oncogenic KRASv12. We have completed a cell-based high-throughput screen within UT Southwestern's 200,000 compound library utilizing the most cancer progressed isogenic cell line and tested the initial hits against the TERT immortalized normal diploid HCECs. A small molecule lead compound, TASIN-1 (truncated APC selective inhibitor), was identified from this screen that is selectively toxic towards a panel of colon cancer cell lines with APC truncations while sparing normal diploid HCECs and cancer cells with wild type APC. TASIN-1 and its analogs (with IC50s from 0.01nM to 5µM) represent a novel strategy for the treatment of colon cancer. In vitro and in vivo preclinical results will be presented.

Smad7 induces plasticity in tumor-infiltrating Th17 cells and enables TNF-alpha-mediated killing of colorectal cancer cells

Transforming growth factor-beta (TGF-β) is deeply involved in colorectal cancer development and the disruption of the TGF-β signaling in dysplastic cells is required for tumor to grow. Nevertheless, tumor cells express TGF-β to escape the immune surveillance mediated by T cells. T-cell expression of Smad7, an intracellular inhibitor of the TGF-β signaling, protects against colitis-associated colorectal cancer. However, whether Smad7 in T cells might influence colorectal cancer growth independently of chronic inflammation and which T-cell subset is involved in this process is unknown. To address this issue, T-cell-specific Smad7 transgenic mice and wild-type (WT) littermates were subcutaneously transplanted with syngenic MC38 colon carcinoma cells. Smad7Tg mice were resistant to tumor development compared with WT mice and protection was dependent on CD4(+) T cells. Smad7 expression in T cells increased the number of tumor-infiltrating Tbet/ROR-γ-t double-positive CD4 T cells characterized by the expression of tumor necrosis factor-alpha (TNF-α) and interferon-gamma but lower IL17A. The low expression of IL17A caused by the Smad7 expression in tumor-infiltrating CD4(+) T cells enabled the TNF-α-mediated killing of cancer cells both in vitro and in vivo, thus indicating that the Smad7-mediated plastic effect on T-cell phenotype induces protection against colorectal cancer.

Synergistic killing of colorectal cancer cells by oxaliplatin and ABT-737

Oxaliplatin is frequently used in the treatment of metastatic colorectal cancer (CRC). Our previous work shows that oxaliplatin induces the pro-apoptotic protein Noxa in CRC cells. The Bcl2-inhibitor ABT-737 is particularly effective in cells with high Noxa levels. Therefore, we tested whether oxaliplatin and ABT-737 display synergy in killing CRC cells. A panel of CRC cell lines was treated with oxaliplatin and ABT-737, either alone or in combination. Apoptosis was measured by FACS analysis of sub-G1 DNA content and by Western blot analysis of caspase-3 processing. Noxa expression was suppressed by lentiviral RNA interference. Oxaliplatin and ABT-737 displayed a strong synergistic apoptotic response, which was dependent on wildtype TP53 and oncogenic KRAS. TP53 and KRAS were required for drug-induced Noxa expression and this was essential for tumor cell apoptosis. Oxaliplatin, but not ABT-737, induced p53 accumulation, but both drugs stimulated Noxa expression. Combination treatment of mice with subcutaneous tumor xenografts drastically reduced tumor volume, while single drug treatment had no effect. ABT-737 synergizes with oxaliplatin to kill colorectal cancer cells. This requires induction of Noxa by wildtype TP53 and oncogenic KRAS. Future studies should explore the anti-tumor efficacy of this drug combination in mouse models for spontaneous CRC development and in patient-derived tumor cell cultures and xenografts.

Gold hybrid nanoparticles for targeted phototherapy and cancer imaging

Gold and iron oxide hybrid nanoparticles (HNPs) synthesized by the thermaldecomposition technique are bio-functionalized with a single chain antibody, scFv,that binds to the A33 antigen present on colorectal cancer cells. The HNP–scFvconjugates are stable in aqueous solution with a magnetization value of 44 emu g − 1 and exhibit strong optical absorbance at 800 nm. Here we test this material in targeting,imaging and selective thermal killing of colorectal cancer cells. Cellular uptakestudies showed that A33-expressing cells take up the A33scFv-conjugated HNPs ata rate five times higher than cells that do not express the A33 antigen. Laserirradiation studies showed that approximately 53% of the A33-expressing cellsexposed to targeted HNPs are killed after a six-minute laser treatment at 5.1 W cm − 2 using a 808 nm continuous wave laser diode while < 5% of A33-nonexpressing cells are killed. At a higher intensity, 31.5 W cm − 2, the thermal destruction increases to 99 and 40% for A33-expressing cellsand A33 nonexpressing cells, respectively, after 6 min exposure. Flowcytometric analyses of the laser-irradiated A33 antigen-expressing cells showapoptosis-related cell death to be the primary mode of cell death at 5.1 W cm − 2, with increasing necrosis-related cell death at higher laser power. These results suggestthat this new class of bio-conjugated hybrid nanoparticles can potentially serve as aneffective antigen-targeted photothermal therapeutic agent for cancer treatment as well as aprobe for magnetic resonance-based imaging.

Antioxidants potentiate American ginseng-induced killing of colorectal cancer cells

Colorectal cancer is the third leading cause of cancer-related deaths in the United States. Novel prevention or therapeutic agents are needed to better manage this disease. American ginseng is a commonly used herb and is believed to have lots of health benefits, including anti-cancer activities. However there have been very few in-depth studies of the activities of this herb at the molecular level. In this report we showed that 4 h-steamed American ginseng root extract (S4h) induced mitochondrial damage, increased reactive oxygen species (ROS), and apoptosis in colorectal cancer cells. We showed that the NF-κB pathway was activated by S4h and that removal of ROS inhibited S4h-induced NF-κB activation. We further showed that both antioxidants and a specific inhibitor of the NF-κB pathway enhanced S4h-induced cell death. Finally, we showed that protecting the mitochondria decreased both the level of ROS and apoptosis. Taken together, these results indicate that S4h-induced apoptosis in colorectal cancer cells is mediated by mitochondria damage and that damage to the mitochondria activates both the apoptosis pathway and the ROS/NF-κB mediated survival pathway. These results further suggest that the anti-cancer effect of steamed ginseng can be enhanced by antioxidants or inhibitors of the NF-κB pathway.

The effect of radio-adaptive doses on HT29 and GM637 cells

BackgroundThe shape of the dose-response curve at low doses differs from the linear quadratic model. The effect of a radio-adaptive response is the centre of many studies and well known inspite that the clinical applications are still rarely considered.MethodsWe studied the effect of a low-dose pre-irradiation (0.03 Gy – 0.1 Gy) alone or followed by a 2.0 Gy challenging dose 4 h later on the survival of the HT29 cell line (human colorectal cancer cells) and on the GM637 cell line (human fibroblasts).Results0.03 Gy given alone did not have a significant effect on both cell lines, the other low doses alone significantly reduced the cell survival. Applied 4 h before the 2.0 Gy fraction, 0.03 Gy led to a significant induced radioresistance in GM637 cells, but not in HT29 cells, and 0.05 Gy led to a significant hyperradiosensitivity in HT29 cells, but not in GM637 cells.ConclusionA pre-irradiation with 0.03 Gy can protect normal fibroblasts, but not colorectal cancer cells, from damage induced by an irradiation of 2.0 Gy and the application of 0.05 Gy prior to the 2.0 Gy fraction can enhance the cell killing of colorectal cancer cells while not additionally damaging normal fibroblasts. If these findings prove to be true in vivo as well this may optimize the balance between local tumour control and injury to normal tissue in modern radiotherapy.