5-Fluorouracil Mediates Apoptosis and G1/S Arrest in Laryngeal Squamous Cell Carcinoma via a p53-Independent Pathway

A systematic review of the therapeutic effects of resveratrol in combination with 5-fluorouracil during colorectal cancer treatment: with a special focus on the oxidant, apoptotic, and anti-inflammatory activities

Purpose

5-fluorouracil (5-FU), an effective chemotherapy drug, is commonly applied for colorectal cancer treatment. Nevertheless, its toxicity to normal tissues and the development of tumor resistance are the main obstacles to successful cancer chemotherapy and hence, its clinical application is limited. The use of resveratrol can increase 5-FU-induced cytotoxicity and mitigate the unwanted adverse effects. This study aimed to review the potential therapeutic effects of resveratrol in combination with 5-FU against colorectal cancer.

Methods

According to the PRISMA guideline, a comprehensive systematic search was carried out for the identification of relevant literature in four electronic databases of PubMed, Web of Science, Embase, and Scopus up to May 2021 using a pre-defined set of keywords in their titles and abstracts. We screened 282 studies in accordance with our inclusion and exclusion criteria. Thirteen articles were finally included in this systematic review.

Results

The in vitro findings showed that proliferation inhibition of colorectal cancer cells in the groups treated by 5-FU was remarkably higher than the untreated groups and the co-administration of resveratrol remarkably increased cytotoxicity induced by 5-FU. The in vivo results demonstrated a decrease in tumor growth of mice treated by 5-FU than the untreated group and a dramatic decrease was observed following combined treatment of resveratrol and 5-FU. It was also found that 5-FU alone and combined with resveratrol could regulate the cell cycle profile of colorectal cancer cells. Moreover, this chemotherapeutic agent induced the biochemical and histopathological changes in the cancerous cells/tissues and these alterations were synergized by resveratrol co-administration (for most of the cases), except for the inflammatory mediators.

Conclusion

The results obtained from this systematic review demonstrated that co-administration of resveratrol could sensitize the colorectal cancer cells to 5-FU treatment via various mechanisms, including regulation of cell cycle distribution, oxidant, apoptosis, anti-inflammatory effects.

Targeting laryngeal cancer cells with 5-fluorouracil and curcumin using mesoporous silica nanoparticles

Objective:

To explore the inhibitory and synergistic effects of 5-fluorouracil and curcumin on Hep-2 laryngeal cancer cells and clarify the effect of mesoporous silica nanoparticles as drug carriers.

Methods:

The inhibitory effects of 5-fluorouracil and curcumin on Hep-2 cells were detected using the CCK-8 assay. CompuSyn was used to calculate the synergistic effect of the 2 drugs. Flow cytometry was used to detect apoptosis and cell cycle arrest induced by 5-fluorouracil and curcumin. The drugs were loaded into mesoporous nanoparticles. Western blotting was used to detect the expression of related proteins after treatment. The growth of subcutaneous tumors in BALB/c nude after the intraperitoneal injection with drug-loaded mesoporous silica nanoparticles was recorded.

Results:

5-Fluorouracil and curcumin synergistically induced apoptosis and cell cycle arrest in Hep-2 cells. Mesoporous silica nanoparticles as drug carriers enhanced the therapeutic effects of 5-fluorouracil and curcumin.

Conclusions:

Mesoporous silica nanoparticles are expected to be effective drug carriers that enhance the synergistic effects of 5-fluorouracil and curcumin on laryngeal cancer.

Combination of resveratrol and 5-flurouracil enhanced anti-telomerase activity and apoptosis by inhibiting STAT3 and Akt signaling pathways in human colorectal cancer cells

Colorectal cancer is one of the leading causes for mortalities worldwide. The most common cause of colorectal cancer mortality is hepatic metastasis. There has been a limited advancement in the targeted-therapies for metastatic colorectal cancer. Conventional chemotherapeutic agent 5-fluorouracil has been used for various cancer treatments including colorectal cancer. Development of drug resistance and severe toxicity are major hurdles for its use in clinical setting. Resveratrol is a natural polyphenolic compound which has protective effects against aging-related diseases. In this study, we have tested whether combined treatments of resveratrol and 5-FU enhanced inhibitory effects against colorectal cancer cell growth. We herein showed that resveratrol and 5-FU combination treatments caused the anti-cancer activities by simultaneously inhibiting STAT3 and Akt signaling pathways. Resveratrol treatment induced S-phase specific cell cycle arrest, and when combined with 5-FU, it showed further increase in colorectal cancer cell apoptosis. Combined treatments of resveratrol and 5-FU inhibited epithelial-mesenchymal transition. Notably, resveratrol showed anti-inflammatory effects by downregulating inflammatory biomarkers, pSTAT3 and pNFκB. Resveratrol and 5-FU treatments inhibited STAT3 phosphorylation and its binding to the promoter region of human telomerase reverse transcriptase (hTERT). Our data provide the first evidence that resveratrol can enhance anti-telomeric and pro-apoptotic potentials of 5-FU in colorectal cancer, hence lead to re-sensitization to chemotherapy.

Curcumin Analog Pentagamavunon-1 (PGV-1) Sensitizes Widr Cells to 5-Fluorouracil through Inhibition of NF-κB Activation

Cell cycle regulation and the NF-κB pathway in cancer cells are important in mediating resistance to 5-Fluorouracil (5-FU). Pentagamavunon-1 (PGV-1), a curcumin analog, is known to exhibit stronger growth inhibitory effects than curcumin itself in several cancer cells. In this study, we evaluated the potency of PGV-1 in combination with 5-FU in WiDr colon cancer cells. In MTT assays, PGV-1 did not only exhibit stronger growth inhibitory effects than both 5-FU and curcumin, but also enhanced the cytotoxicity of 5-FU. Flow cytometry demonstrated that single treatments with PGV-1 and 5-FU resulted in different effects on cell cycle profiles. PGV-1 induced G2/M arrest while 5-FU caused S-phase arrest at low concentration (1 μM) and G1-phase arrest at high concentration (100 μM). Interestingly, the combination of 5-FU and PGV-1 enhanced cell accumulation in S-phase. Although a single treatment with either 5-FU or PGV-1 increased cyclin D1 at the protein level, the combination treatment resulted in significant suppression. In addition, PGV-1 inhibited activation of NF-κB and suppressed the expression of cyclooxygenase-2, an NF-κB downstream protein. In conclusion, PGV-1 increased the cytotoxic effect of 5-FU on WiDr cells through inhibition of NF-κB activation.

Knockdown of delta-5-desaturase promotes the anti-cancer activity of dihomo-γ-linolenic acid and enhances the efficacy of chemotherapy in colon cancer cells expressing COX-2

Cyclooxygenase (COX), commonly overexpressed in cancer cells, is a major lipid peroxidizing enzyme that metabolizes polyunsaturated fatty acids (ω-3s and ω-6s). The COX-catalyzed free radical peroxidation of arachidonic acid (ω-6) can produce deleterious metabolites (e.g. 2-series prostaglandins) that are implicated in cancer development. Thus, COX inhibition has been intensively investigated as a complementary therapeutic strategy for cancer. However, our previous study has demonstrated that a free radical-derived byproduct (8-hydroxyoctanoic acid) formed from COX-catalyzed peroxidation of dihomo-γ-linolenic acid (DGLA, the precursor of arachidonic acid) can inhibit colon cancer cell growth. We thus hypothesize that the commonly overexpressed COX in cancer (~90% of colon cancer patients) can be taken advantage to suppress cell growth by knocking down delta-5-desaturase (D5D, a key enzyme that converts DGLA to arachidonic acid). In addition, D5D knockdown along with DGLA supplement may enhance the efficacy of chemotherapeutic drugs. After knocking down D5D in HCA-7 colony 29 cells and HT-29 cells (human colon cancer cell lines with high and low COX levels, respectively), the antitumor activity of DGLA was significantly enhanced along with the formation of a threshold range (~0.5-1.0μM) of 8-hydroxyoctanoic acid. In contrast, DGLA treatment did not inhibit cell growth when D5D was not knocked down and only limited amount of 8-hydroxyoctanoic acid was formed. D5D knockdown along with DGLA treatment also enhanced the cytotoxicities of various chemotherapeutic drugs, including 5-fluorouracil, regorafenib, and irinotecan, potentially through the activation of pro-apoptotic proteins, e.g. p53 and caspase 9. For the first time, we have demonstrated that the overexpressed COX in cancer cells can be utilized in suppressing cancer cell growth. This finding may provide a new option besides COX inhibition to optimize cancer therapy. The outcome of this translational research will guide us to develop a novel ω-6-based diet-care strategy in combination with current chemotherapy for colon cancer prevention and treatment.

Comparative evaluation of PLGA nanoparticle delivery system for 5-fluorouracil and curcumin on squamous cell carcinoma

PURPOSE

The purpose of this study is to assess the effect of 5-fluorouracil nanoparticles and curcumin naoparticles on cell proliferation and the expression of the apoptotic marker (caspase 3) in squamous cell carcinoma cell line.

MATERIAL AND METHODS

PLGA 5-fluorouracil nanopartciles and PLGA curcumin nanoparticles were prepared and applied for 24 and 48h on human laryngeal squamous carcinoma cell line (Hep-2) as regard IC 50 concentration. MTT assay was used for evaluation of cytotoxicity of prepared nanoparticles. Quantitaive reverse transcriptase polymerase chain reaction (QRT-PCR) was used for the assessment of caspase-3 expression in the treated cell line.

RESULTS

The drug release rate profiles was dependent upon polymer to drug ratio, noting that the higher PLGA polymer ratio to 5-fluprouracil or curcumin drug showed faster release rates. On the other hand, the least PLGA polymer ratio to 5-fluprouracil or curcumin drug showed the slowest release rates. MTT assay revelaed that 5-fluorouracil nanoparticels or curcumin nanoparticels showed a clear cytotoxic effect on Hep-2 cell line compared to non treated cancer cells. The RT-PCR assessment of caspase-3 expression revealed that there was a significant increase in caspase-3 expression in Hep-2 cell line treated with 5-fluorouracil nanoparticles or curcumin compared to non treated cancer cells.

CONCLUSION

Curcumin nanoparticles could be more active in inducing apoptosis in short term assays (24h) than long term assays (48h) due to differential cellular uptake. While 5-fluorouracil nanoparticles induced higher significant apoptosis in long term (48h) compared to curcumin group.

Knockdown of Merm1/Wbscr22 attenuates sensitivity of H460 non-small cell lung cancer cells to SN-38 and 5-FU without alteration to p53 expression levels

Merm1/Wbscr22 is a novel metastasis promoter that has been shown to be involved in tumor metastasis, viability and apoptosis. To the best of our knowledge, there are currently no studies suggesting the possible correlation between the expression of Merm1/Wbscr22 in tumor cells and chemosensitivity to antitumor agents. In the present study, two human non-small cell lung cancer cell lines, H1299 and H460, were used to investigate whether Merm1/Wbscr22 affects chemosensitivity to antitumor agents, including cisplatin (CDDP), doxorubicin (ADM), paclitaxel (PTX), mitomycin (MMC), 7-Ethyl-10-hydroxycamptothecin (SN-38; the active metabolite of camptothecin) and 5-fluorouracil (5-FU). Merm1/Wbscr22 knockdown cell lines (H1299-shRNA and H460-shRNA) and negative control cell lines (H1299-NC and H460-NC) were established by stable transfection, and the efficiency of Merm1/Wbscr22 knockdown was confirmed by western blotting, immunofluorescence microscopy and quantitative polymerase chain reaction. The results demonstrated that shRNA-mediated knockdown of Merm1/Wbscr22 did not affect cell proliferation in vitro and in vivo. The H460 cells harboring wild type p53 were markedly more sensitive to all six antitumor agents as compared with the p53-null H1299 cells. Downregulation of Merm1/Wbscr22 did not affect H1299 sensitivity to any of the six antitumor agents, whereas attenuated H460 sensitivity to SN-38 and 5-FU, without significant alteration in p53 at both mRNA and protein levels, was identified. The reduced H460 sensitivity to SN-38 was further confirmed in vivo. SN-38 demonstrated significant tumor growth inhibitory activity in both H460 and H460‑NC tumor xenograft models, but only marginally suppressed the H460-shRNA xenograft tumor growth. Furthermore, CDDP (4, 10, 15 µg/ml)-resistant human non-small lung cancer cells A549 (A549-CDDPr-4, 10, 15) expressed significant amounts of Merm1/Wbscr22 protein, as compared with the parental A549 cells. In conclusion, shRNA-mediated knockdown of Merm1/Wbscr22 attenuates H460 sensitivity to SN-38 and 5-FU, suggesting Merm1/Wbscr22 is involved in chemosensitivity to SN-38 and 5-FU in H460 cells. No direct correlation between the p53 expression level and altered chemosensitivity was identified.

Cyclin E and histone H3 levels are regulated by 5-fluorouracil in a DNA mismatch repair-dependent manner

Several studies indicate that the DNA mismatch repair (MMR) system may trigger cytotoxicity upon 5-fluorouracil (5-FU) recognition, but signaling pathways regulated by MMR in response to 5-FU are unknown. We hypothesize that recognition of 5-FU in DNA by MMR proteins trigger specific signaling cascades that results in slowing of the cell cycle and cell death. Whole human genome cDNA microarrays were used to examine relative signaling responses induced in MMR-proficient cells after 5-FU (5 μM) treatment for 24 hours. Analysis revealed 43 pathways differentially affected by 5-FU compared to control (P 1.4-fold) and downregulated cdc25C, cyclins B1 and B2, histone H2A, H2B, and H3 (< -1.4-fold) over control. Cell cycle analysis revealed a G1/S arrest by 5-FU that was congruent with increased cyclin E and decreased cdc25C protein expression. Importantly, with knockdown of hMLH1 and hMSH2, we observed that decreased histone H3 expression by 5-FU was dependent on hMLH1. Additionally, 5-FU treatment dramatically decreased levels of several histone H3 modifications. Our data suggest that 5-FU induces a G1/S arrest by regulating cyclin E and cdc25C expression, and MMR recognition of 5-FU in DNA may modulate cyclin E to affect the cell cycle. Furthermore, MMR recognition of 5-FU reduces histone H3 levels that could be related to DNA access by proteins and/or cell death during the G1/S phase of the cell cycle.

Thymidylate synthase inhibition induces p53-dependent and p53-independent apoptotic responses in human urinary bladder cancer cells

PURPOSE

In search for more effective clinical protocols, the antimetabolite drug 5-fluorouracil (5-FU) has been successfully included in new regimens of bladder cancer combination chemotherapy. In the present study, we have investigated the effects of 5-FU treatment on apoptosis induction in wild-type and mutant p53 urinary bladder cancer cells.

METHODS

We have used MTT-based assays, FACS analysis, Western blotting and semi-quantitative RT-PCR in RT4 and RT112 (grade I, wild-type p53), as well as in T24 (grade III, mutant p53) and TCCSUP (grade IV, mutant p53) human urinary bladder cancer cell lines.

RESULTS

In the urothelial bladder cancer cell lines RT4 and T24, 5-FU-induced TS inhibition proved to be associated with cell type-dependent (a) sensitivity to the drug, (b) Caspase-mediated apoptosis, (c) p53 stabilization and activation, as well as Rb phosphorylation and E2F1 expression and (d) transcriptional regulation of p53 target genes and their cognate proteins, while an E2F-dependent transcriptional network did not seem to be critically engaged in such type of responses.

CONCLUSIONS

We have shown that in the wild-type p53 context of RT4 cells, 5-FU-triggered apoptosis was prominently efficient and mainly regulated by p53-dependent mechanisms, whereas the mutant p53 environment of T24 cells was able to provide notable levels of resistance to apoptosis, basically ascribed to E2F-independent, and still unidentified, pathways. Nevertheless, the differential vulnerability of RT4 and T24 cells to 5-FU administration could also be associated with cell-type-specific transcriptional expression patterns of certain genes critically involved in 5-FU metabolism.

Inhibition of alpha-mannosidase Man2c1 gene expression suppresses growth of esophageal carcinoma cells through mitotic arrest and apoptosis

To study the effects of suppressed alpha-mannosidase Man2c1 gene expression on EC9706 human esophageal carcinoma cells, the cells were treated with short interfering RNA. Growth inhibition of EC9706 cells was observed when Man2c1 expression was inhibited in this way. Flow cytometric analysis showed accumulation of cells in S and G(2)-M phases, as well as cell apoptosis. The mitotic index test showed cell-cycle arrest at the M checkpoint. Although the percentage of cells in (pro)metaphase increased, the proportion of cells in anaphase and telophase decreased. Apoptosis was trigged by mitotic arrest. Furthermore, microtubules in EC9607 cells were examined by means of fluorescence staining of alpha-tubulin. Although control cells showed a nest-like microtubule network, the microtubule network in experimental cells was vague and condensed at the perinuclear region. Some cells with Man2c1 suppression had large protrusions of cytoplasm, some of which linked with the main body through a long, thin connection. Western blotting showed that tubulin polymerization was inhibited. The data imply that induction of mitotic arrest and consequent apoptosis resulted from microtubule disorganization, which appears to be one of the major cellular mechanisms by which suppressed expression of the Man2c1 gene causes growth inhibition of EC9706 esophageal carcinoma cells. In addition, Man2c1 suppression results in upregulation of E-cadherin, alpha-catenin, and beta-catenin expression in cells.

Induction of cell cycle arrest and apoptosis by 5-fluorouracil in laryngeal cancer cells containing HPV16 E6 and E7 oncoproteins

OBJECTIVE

To investigate the cytotoxic effect of 5-fluorouracil (5Fu) on HPV16-associated laryngeal cancer cells.

DESIGN AND METHODS

Cytotoxicity assay and TUNEL assay were used to assess the effect of 5Fu on laryngeal cancer cells transfected with HPV16 E6 or E7.

RESULTS

5Fu induced apoptosis in the cells either with or without HPV16 in a dose- and time-dependent manner. 5Fu caused the accumulation of active pRb and p21(WAF1/CIP1), together with an increase in Bak and Bax expression and a decrease in Bcl-2 levels in all the transfected cells. G(1)/S phase cell cycle arrest was associated with the antiproliferation activity of 5Fu. 5Fu also presented some effects on the E6 and E7 oncoproteins.

CONCLUSIONS

HPV16 E6 and E7 oncoproteins do not prevent 5Fu-medicated apoptosis and G(1)/S cell arrest in laryngeal cancers. The sensitivity of 5Fu treatment is associated with the decrease of Bcl-2 and/or the increase in Bak and p21(WAFI/CIP1).