BH3 profiling discriminates the anti‑apoptotic status of 5‑fluorouracil‑resistant colon cancer cells

Bcl‑xL‑specific BH3 mimetic A‑1331852 suppresses proliferation of fluorouracil‑resistant colorectal cancer cells by inducing apoptosis

BH3 mimetics are small‑molecule inhibitors of the antiapoptotic Bcl‑2 family and have therapeutic efficacy against hematological malignancies. BH3 mimetic A‑1331852 suppresses colorectal cancer cell proliferation. Progressive resistance to the widely used anticancer agent fluorouracil (5‑FU) is a key reason for colorectal cancer recurrence; therefore, the present study tested if A‑1331852 can suppress the proliferation of 5‑FU‑resistant colorectal cancer cells. A 5‑FU‑resistant colorectal cancer cell line was derived from HCT116 cells and compared with the parental line. Expression levels of the antiapoptotic Bcl‑2 proteins Bcl‑xL and myeloid cell leukemia 1 (Mcl‑1) were determined via western blotting, proliferation in the presence of 5‑FU and following small interfering (si)RNA‑mediated Bcl‑xL or Mcl‑1 knockdown was assessed by WST‑1 assay and sensitivity to A‑1331852‑induced apoptosis was assessed via western blotting and DNA fragmentation assay. In addition, a xenograft mouse model of 5‑FU‑resistant colorectal cancer was established via subcutaneous inoculation of 5‑FU‑resistant HCT116 cells to examine the in vivo antitumor efficacy of A‑1331852. Compared with the parental line, 5‑FU‑resistant cells overexpressed Bcl‑xL. Knockdown of Bcl‑xL by siRNA and treatment with A‑1331852 suppressed proliferation and induced the apoptosis of both 5‑FU‑resistant and parental HCT116 cells, but the potency of both effects was stronger in 5‑FU‑resistant than parental HCT116 cells. Furthermore, A‑1331852 suppressed the growth of xenograft tumors derived from 5‑FU‑resistant cells by inducing apoptosis. Overall, the present findings suggested that Bcl‑xL upregulation contributes to 5‑FU resistance of colorectal cancer and targeted inhibition by A‑1331852 may be an effective treatment strategy.

IL-1β enhances cell viability and decreases 5-FU sensitivity in novel colon cancer cell lines derived from African American patients

Background

In the U.S., African Americans (AAs) present with the highest incidence and mortality rates for Colorectal Cancer (CRC). When compared to Caucasian American (CA) patients, AAs also have reduced response to the first line standard of care chemotherapeutic agent 5-Fluorouracil (5-FU). Previously, we observed differential gene expression between the two populations, suggesting that colon tumors from AA patients display a decreased antitumor immune response and an increased expression of genes encoding proteins involved in inflammatory processes, such as Interleukin-1β (IL-1β). Here, we investigate the role of IL-1β in modifying chemotherapeutic response and altering expression of proteins in novel AA and well-established CA colon cancer cell lines.

Methods

RNA sequencing analysis was performed to detect expression of genes involved in inflammation in AA and CA colon cancer cells. The effects of IL-1β on 5-FU response was evaluated by assessing cell viability (MTS assay) and apoptosis (flow cytometry analysis) following treatment with 5-FU alone or in combination with the cytokine. Further, we used an IL-1 receptor antagonist (IL-1Ra) to inhibit IL-1β-induced effects on 5-FU sensitivity and NF-kB pathway activation.

Results

AA colon cancer cell lines present significant increase in expression of genes IL1R2 (373-fold change (FC), IRAK1 (3.24 FC), IKBKB, (5.33 FC) NF-KB IA (5.95 FC), MYD88, (3.72 FC), IRAK3 (161 FC), TRAF5 (4.1 FC). A significant decrease in the response to 5-FU treatment, as well as a significant increase in phosphorylation of IκBα and secretion of IL-8, was seen following IL-1β treatment, in both AA and CA cell lines. Finally, treatment with IL-1Ra was able to reverse the effects induced by IL-1β, by increasing the cells sensitivity to 5-FU. IL-1Ra also inhibited phosphorylation of IκBα and IL-8 secretion.

Conclusions

Our results suggest a differential expression of inflammatory genes and proteins that might regulate the different response to IL-1β between AA and CA colon cancer cell lines. Our data also demonstrates that IL-1β is involved in modulating 5-FU response in both AA and CA colon cancer cell lines. Further investigation of these mechanisms might help elucidate the differences seen in incidence, mortality and response to therapy in AA colon cancer patients.

KIFC3 Promotes Proliferation, Migration, and Invasion in Colorectal Cancer via PI3K/AKT/mTOR Signaling Pathway

Background: KIFC3, belongs to kinesin superfamily proteins (KIFs), is well known for its role in intracellular cargo movement. KIFC3 has been identified as a docetaxel resistance gene in breast cancer cells, however, the role of KIFC3 and its potential mechanism in colorectal cancer (CRC) remains elusive.

Objectives: We aims to investigate the effects of KIFC3 in proliferation, migration, and invasion in CRC as well as the potential mechanism inside.

Methods: We investigated the expression of KIFC3 in the Oncomine, Gene Expression Profiling Interactive Analysis databases. The KIFC3 protein expression and mRNA level in CRC cells were evaluated by western blot and qRT-PCR. Cell proliferation ability was detected by CCK-8, EdU, colony formation assay and xenograft tumor in nude mice. Flow cytometry was used to detect the cell cycle. The effect of KIFC3 on the epithelial-to-mesenchymal transition (EMT) was investigated by transwell and wound healing assay. The association of KIFC3 with EMT and PI3K/AKT/mTOR signaling pathway were measured by western blot and immunofluorescence staining.

Results: The expression of KIFC3 was higher in CRC tissues than normal colorectal tissue, and was negatively correlated with the overall survival of patients with CRC. KIFC3 silencing inhibited the proliferation, migration and invasion of CRC cells. Meanwhile, it could decrease the number of cells in S phase. KIFC3 silencing inhibited the expression of proliferating cell nuclear antigen, Cyclin A2, Cyclin E1, and CDK2 and increased the expression of p21 and p53. KIFC3 overexpression promoted the G1/S phase transition. KIFC3 silencing inhibited the EMT process, which decreased the level of N-cadherin, Vimentin, SNAIL 1, TWIST, MMP-2, MMP-9 and increased E-cadherin, while KIFC3 overexpression show the opposite results. Furthermore, the knockdown of KIFC3 suppressed the EMT process by modulating the PI3K/AKT/mTOR signaling pathway. KIFC3 silencing decreased the expression of phosphorylated PI3K, AKT, mTOR, but total PI3K, AKT, mTOR have no change. Inversely, the upregulation of KIFC3 increased the expression of phosphorylated PI3K, AKT and mTOR, total PI3K, AKT, mTOR have no change. In a xenograft mouse model, the depletion of KIFC3 suppressed tumor growth. the increased expression levels of KIFC3 could enhance the proliferation, migration and invasion of CRC cells, and enhance the EMT process through the PI3K/AKT/mTOR pathway.

Conclusion: Our study substantiates that KIFC3 can participate in the regulation of CRC progression by which regulates EMT via the PI3K/AKT/mTOR axis.

The manipulation of apoptosis for cancer therapy using BH3-mimetic drugs

Apoptosis is a form of programmed cell death that is regulated by the balance between prosurvival and proapoptotic BCL-2 protein family members. Evasion of apoptosis is a hallmark of cancer that arises when this balance is tipped in favour of survival. One form of anticancer therapeutic, termed 'BH3-mimetic drugs', has been developed to directly activate the apoptosis machinery in malignant cells. These drugs bind to and inhibit specific prosurvival BCL-2 family proteins, thereby mimicking their interaction with the BH3 domains of proapoptotic BCL-2 family proteins. The BCL-2-specific inhibitor venetoclax is approved by the US Food and Drug Administration and many regulatory authorities worldwide for the treatment of chronic lymphocytic leukaemia and acute myeloid leukaemia. BH3-mimetic drugs targeting other BCL-2 prosurvival proteins have been tested in preclinical models of cancer, and drugs targeting MCL-1 or BCL-X_L have advanced into phase I clinical trials for certain cancers. As with all therapeutics, efficacy and tolerability need to be carefully balanced to achieve a therapeutic window whereby there is significant anticancer activity with an acceptable safety profile. In this Review, we outline the current state of BH3-mimetic drugs targeting various prosurvival BCL-2 family proteins and discuss emerging data regarding primary and acquired resistance to these agents and approaches that may overcome this. We highlight issues that need to be addressed to further advance the clinical application of BH3-mimetic drugs, both alone and in combination with additional anticancer agents (for example, standard chemotherapeutic drugs or inhibitors of oncogenic kinases), for improved responses in patients with cancer.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

BH3 Mimetic Sensitivity of Colorectal Cancer Cell Lines in Correlation with Molecular Features Identifies Predictors of Response

Colorectal cancer (CRC) is a heterogeneous disease, which in part explains the differential response to chemotherapy observed in the clinic. BH3 mimetics, which target anti-apoptotic BCL-2 family members, have shown potential in the treatment of hematological malignancies and offer promise for the treatment of solid tumors as well. To gain a comprehensive understanding of the response to BH3 mimetics in CRC and the underlying molecular factors predicting sensitivity, we screened a panel of CRC cell lines with four BH3 mimetics targeting distinct anti-apoptotic BCL-2 proteins. Treatment with compounds alone and in combination revealed potent efficacy of combined MCL-1 and BCL-XL inhibition in inducing CRC cell death, irrespective of molecular features. Importantly, expression of the anti-apoptotic protein target of BH3 mimetics on its own did not predict sensitivity. However, the analysis did identify consensus molecular subtype (CMS) specific response patterns, such as higher resistance to single and combined BCL-2 and MCL-1 inhibition in CMS2 cell lines. Furthermore, analysis of mutation status revealed that KRAS mutant cell lines were more resistant to MCL-1 inhibition. Conclusively, we find that CRC cell lines presented with distinct responses to BH3 mimetics that can in part be predicted by their CMS profile and KRAS/BRAF mutations. Overall, almost all CRC lines share sensitivity in the nanomolar range to combined MCL-1 and BCL-XL targeting suggesting that this would be the preferred approach to target these cancers.

Acanthopanax senticosus Harms extract causes G0/G1 cell cycle arrest and autophagy via inhibition of Rubicon in human liver cancer cells

Acanthopanax senticosus (Rupr. et Maxim) Harms (ASH), also known as Siberian ginseng or eleuthero, is a hardy shrub native to China, Korea, Russia and the northern region of Japan. ASH is used for the treatment of several diseases such as heart disease, hypertension, rheumatoid arthritis, allergies, chronic bronchitis, diabetes and cancer. In the present study, the inhibitory effect of the root extract of ASH (ASHE) on HuH-7 and HepG2 liver cancer cells was examined. ASHE suppressed liver cancer cell proliferation by inducing cell cycle arrest at the G0/G1 phase, as well as apoptosis, as indicated by the increased number of Annexin V and 7-AAD-positive cells. Furthermore, the expression of LC3-II, an autophagy marker, in these cells also increased post treatment with ASHE. LC3-II induction was further enhanced by co-treatment with chloroquine. Fluorescence and transmission electron micrographs of ASHE-treated liver cancer cells showed the presence of an increased number of autophagic vesicles. A decreased protein expression level of run domain Beclin-1-interacting and cysteine-rich domain-containing, an autophagy inhibitor, with no change in RUBCN mRNA expression was observed, indicating activation of the autophagosome-lysosome fusion step of autophagy. In conclusion, ASHE exerts cytostatic activity on liver cancer cells via both apoptosis and autophagy, and may serve as a potential therapeutic agent for management of liver cancer and autophagy-related diseases.