Anti-proliferative and pro-apoptotic effects of 3,3'-diindolylmethane in human cervical cancer cells

Research Progress of Indole Alkaloids: Targeting MAP Kinase Signaling Pathways in Cancer Treatment

Cancer is the leading cause of morbidity and mortality in people throughout the world. There are many signaling pathways associated with cancerous diseases, from which the Mitogen-activated protein kinase (MAPK) pathway performs a significant role in this regard. Apoptosis and proliferation are correlated with MAPK signaling pathways. Plenty of experimental investigations were carried out to assess the role of indole alkaloids in MAPK-mediated cancerous diseases. Previous reports established that indole alkaloids, such as vincristine and evodiamine are useful small molecules in cancer treatment via the MAPK signaling system. Indole alkaloids have the anticancer potential through different pathways. Vincristine and evodiamine are naturally occurring indole alkaloids that have strong anticancer properties. Additionally, much research is ongoing or completed with molecules belonging to this group. The current review aims to evaluate how indole alkaloids affect the MAPK signaling pathway in cancer treatment. Additionally, we focused on the advancement in the role of indole alkaloids, with the intention of modifying the MAPK signaling pathways to investigate potential new anticancer small molecules. Furthermore, clinical trials with indole alkaloids in cancer treatment are also highlighted.

Antitumor Effects of Carvacrol and Thymol: A Systematic Review

Background: It is estimated that one in five people worldwide faces a diagnosis of a malignant neoplasm during their lifetime. Carvacrol and its isomer, thymol, are natural compounds that act against several diseases, including cancer. Thus, this systematic review aimed to examine and synthesize the knowledge on the antitumor effects of carvacrol and thymol.

Methods: A systematic literature search was carried out in the PubMed, Web of Science, Scopus and Lilacs databases in April 2020 (updated in March 2021) based on the PRISMA 2020 guidelines. The following combination of health descriptors, MeSH terms and their synonyms were used: carvacrol, thymol, antitumor, antineoplastic, anticancer, cytotoxicity, apoptosis, cell proliferation, in vitro and in vivo. To assess the risk of bias in in vivo studies, the SYRCLE Risk of Bias tool was used, and for in vitro studies, a modified version was used.

Results: A total of 1,170 records were identified, with 77 meeting the established criteria. The studies were published between 2003 and 2021, with 69 being in vitro and 10 in vivo. Forty-three used carvacrol, 19 thymol, and 15 studies tested both monoterpenes. It was attested that carvacrol and thymol induced apoptosis, cytotoxicity, cell cycle arrest, antimetastatic activity, and also displayed different antiproliferative effects and inhibition of signaling pathways (MAPKs and PI3K/AKT/mTOR).

Conclusions: Carvacrol and thymol exhibited antitumor and antiproliferative activity through several signaling pathways. In vitro, carvacrol appears to be more potent than thymol. However, further in vivo studies with robust methodology are required to define a standard and safe dose, determine their toxic or side effects, and clarify its exact mechanisms of action.

This systematic review was registered in the PROSPERO database (CRD42020176736) and the protocol is available at https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=176736.

Anti-Cancer Effects of 3, 3'-Diindolylmethane on Human Hepatocellular Carcinoma Cells Is Enhanced by Calcium Ionophore: The Role of Cytosolic Ca2+ and p38 MAPK

Purpose: 3,3'-Diindolylmethane (DIM), derived from indole-3-carbinol (I3C) in the Brassica species of cruciferous vegetables, has anticancer effects, but its exact underlying mechanism of action is unknown. We explored the roles of cytosolic free calcium ([Ca2+]i) and p38 MAPK in the anti-cancer effects of DIM in human hepatocellular carcinoma cells. Methods: Cell proliferation was measured with a Cell Counting Kit-8 (CCK-8) and the clonogenic formation assay. Cell apoptosis was examined by flow cytometric analysis and Hoechst dye staining. Cleaved-caspase3, cleaved-PARP, Bax, total, and phosphorylated p38 MAPK were assayed by western blotting. [Ca2+]i was measured with Fluo-3/AM by fluorescence microscopy. A23187, a calcium ionophore, was used to increase [Ca2+]i levels. Results: DIM inhibited cell proliferation in both SMMC-7721 and HepG2 cells in a concentration- and time-dependent manner. DIM also enhanced phosphorylation of p38 MAPK (p-p38), which was attenuated by SB203580. The proliferation inhibition and apoptosis induction by DIM were also blunted. In addition, DIM increased [Ca2+]i in HCC cells, and this effect was inhibited by the calcium chelator, BAPTA-AM, resulting in reduced p-p38 MAPK activation and apoptosis in DIM-treated cells, though the proliferation inhibition by DIM was unchanged. However, the DIM-induced cell proliferation inhibition and apoptosis were significantly enhanced by A23187, a selective calcium ionophore, which was attributed to exaggerated p-p38 MAPK. Conclusions: The calcium ionophore enhanced DIM-induced anti-cancer effects in hepatocellular carcinoma cells, secondary to [Ca2+]i-dependent activation of p38 MAPK. Treatment with a combination of DIM and calcium ionophore may offer a new approach to enhance the chemotherapeutic efficacy in liver cancer.

3,3'-Diindolylmethane suppresses ovarian cancer cell viability and metastasis and enhances chemotherapy sensitivity via STAT3 and Akt signaling in vitro and in vivo

Signal transducer and activator of transcription-3 (STAT3) protein is constitutively activated in ovarian cancer. The purpose of this study was to investigate the effects of 3,3'-diindolylmethane (DIM) on the regulation of STAT3 signaling and ovarian cancer cell viability, invasion, and sensitivity to chemotherapy. Ovarian cancer SKOV3 and A2780 cell lines were treated with various concentrations of DIM for different periods of time for assessment of cell viability as well as gene expression before and after knockdown of STAT3 expression using STAT3 shRNA. DIM treatment potently suppressed the viabilities of ovarian cancer cells. Consequently, DIM inhibited xenograft growth in nude mice. In addition, at the gene level, DIM inhibited phosphorylation of STAT3 and AKT proteins and expression of their downstream proteins. Moreover, knockdown of STAT3 expression significantly enhanced DIM antitumor activity and cisplatin sensitivity. Their combination suppressed the protein expression of survivin, Bcl-2, Mcl-1, HIF-1α, VEGF, and MMPs, but activated caspase-3. Taken together, the antitumor activity of DIM is via inhibition of the STAT3 and Akt signaling pathways. The combination of STAT3 knockdown with DIM treatment could be further evaluated as a therapeutic strategy for the treatment of advanced ovarian cancer.

Anticancer activity of synthetic bis(indolyl)methane-ortho-biaryls against human cervical cancer (HeLa) cells

Bis(indolyl)methane appended biaryls were designed, synthesized and evaluated in human cervical cancer cell lines (HeLa) for their anticancer activities and compared against normal rat cardiac myoblasts (H9C2) cells. Compounds 1-12 were synthesized, with variations in one of the phenyl unit, in a single step by condensation of biaryl-2-carbaldehydes with indole in the presence of para-toluenesulfonic acid. Compound 1 exhibited a GI50 value of 11.00 ± 0.707 μM and the derivatives, compounds 4 and 11 showed a GI50 value of 8.33 ± 0.416 μM and 9.13 ± 0.177 μM respectively in HeLa cells and was found to be non-toxic to H9C2 cells up to 20 μM. Furthermore, compounds 1, 4 and 11 induced caspase dependent cellular apoptosis in a concentration-dependent manner, reduced mitochondrial membrane potential, inhibited the cell migration and downregulated the production of MMP-2 and MMP-9 in HeLa cells.

Indole-3-Carbinol and Its Role in Chronic Diseases

Indole-3-carbinol (I3C), a common phytochemical in cruciferous vegetables, and its condensation product, 3,3'-diindolylmethane (DIM) exert several biological activities on cellular and molecular levels, which contribute to their well-recognized chemoprevention potential. Initially, these compounds were classified as blocking agents that increase drug-metabolizing enzyme activity. Now it is widely accepted that I3C and DIM affect multiple signaling pathways and target molecules controlling cell division, apoptosis, or angiogenesis deregulated in cancer cells. Although most of the current data support the role of I3C and DIM in prevention of hormone-dependent cancers, it seems that their application in prevention of the other cancer as well as cardiovascular disease, obesity, and diabetes reduction is also possible. This chapter summarizes the current experimental data on the I3C and DIM activity and the results of clinical studies indicating their role in prevention of chronic diseases.

Double-blind randomized placebo-controlled multicenter clinical trial (phase IIa) on diindolylmethane's efficacy and safety in the treatment of CIN: implications for cervical cancer prevention

Background

The article presents the results of a clinical trial on the efficacy and safety of a novel pharmaceutical composition in the form of vaginal suppositories containing diindolylmethane in the course of cervical intraepithelial neoplasia (CIN) I–II conservative treatment. It offers an attractive drug therapy for more personalized prevention of cervical cancer.

Methods

A total of 78 women of reproductive age were included. This was a multicenter, randomized, placebo-controlled, double-blind, parallel-group trial with efficacy determined by histological evaluation of cervical biopsies. The efficacy of active drug treatment (100 and 200 mg/day) in both treatment groups was significantly higher in comparison with the placebo group, according to the primary efficacy end point (proportion of patients with complete CIN regression after 90–180 days of the study drug treatment).

Results

The efficacies were 100.0 % (confidence interval (CI) 95 %: 82.35–100.00 %), 90.5 % (CI 95 %: 69.62–98.83 %), and 61.1 % (CI 95 %: 35.75–82.70 %), for the high dose, low does, and placebo, respectively. Adverse events in the placebo group were reported in 22 % of patients (CI 95 %: 7.5–43.7 %); in the first treatment group (100 mg/day), adverse events were reported in 40.0 % of patients (CI 95 %: 21.1–61.3 %); in the second treatment group (200 mg/day), adverse events were reported in 42.0 % of patients (CI 95 %: 22.1–63.4 %). The differences in side effects between treatment groups treated with the active drug and placebo were statistically significant. No serious adverse events were reported in any of the groups.

Conclusions

Thus, the use of diindolylmethane in the form of intravaginal suppositories can be effective in patients with CIN I–II and is not accompanied by clinically significant side effects. This approach could be a better option for young women with CIN I–II as it takes in attention their reproductive plans.

Trial registration

ID: ChiCTR-INR-15007497 (2 December 2015)

Pro-apoptotic and anti-proliferative effects of 3,3'-diindolylmethane in nasopharyngeal carcinoma cells via downregulation of telomerase activity

The pro-apoptotic and anti-proliferative effects of 3,3'-diindolylmethane (DIM) in various tumor cell types have been widely investigated. The underlying mechanisms were suggested to include cell cycle arrest, cell signaling inhibition and downregulation of the androgen receptor. The present study demonstrated that DIM induced apoptosis and inhibited proliferation in nasopharyngeal carcinoma cells by downregulating the activity of telomerase. The nasopharyngeal carcinoma cell line 5‑8F was selected for this purpose. A cell counting kit‑8 assay and flow cytometry were performed to detect apoptosis and proliferation of 5‑8F cells, respectively, which revealed the pro‑apoptotic and anti‑proliferative effects of DIM. Telomerase activity was detected using a telomeric repeat amplification protocol assay, which revealed that the telomerase activity was inhibited by DIM in a dose‑dependent manner. Reverse transcription polymerase chain reaction was used to detect the mRNA expression levels of human telomerase reverse transcriptase (hTERT) and human telomerase RNA (hTR), and western blot analysis was used to detect the protein expression of hTERT. The results showed that the mRNA and protein expression of hTERT were downregulated in 5‑8F cells following treatment with DIM; however, the mRNA expression of hTR remained unchanged, suggesting that hTERT was the target of DIM. To further identify the target, the length of telomeres was continually measured using a telomere length detection kit, revealing that the telomeres were shortened by DIM in an concentration‑dependent manner. The present study confirmed that DIM had pro‑apoptotic and anti‑proliferative effects in nasopharyngeal carcinoma cells by regulating telomerase.

Methanolic extracts from brown seaweeds Dictyota cilliolata and Dictyota menstrualis induce apoptosis in human cervical adenocarcinoma HeLa cells

Carcinoma of the uterine cervix is the second most common female tumor worldwide, surpassed only by breast cancer. Natural products from seaweeds evidencing apoptotic activity have attracted a great deal of attention as new leads for alternative and complementary preventive or therapeutic anticancer agents. Here, methanol extracts from 13 species of tropical seaweeds (Rhodophytas, Phaeophyta and Chlorophyta) collected from the Northeast of Brazil were assessed as apoptosis-inducing agents on human cervical adenocarcinoma (HeLa). All extracts showed different levels of cytotoxicity against HeLa cells; the most potent were obtained from the brown alga Dictyota cilliolata (MEDC) and Dictyota menstrualis (MEDM). In addition, MEDC and MEDM also inhibits SiHa (cervix carcinoma) cell proliferation. Studies with these two extracts using flow cytometry and fluorescence microscopy showed that HeLa cells exposed to MEDM and MEDC exhibit morphological and biochemical changes that characterize apoptosis as shown by loss of cell viability, chromatin condensation, phosphatidylserine externalization, and sub-G1 cell cycle phase accumulation, also MEDC induces cell cycle arrest in cell cycle phase S. Moreover, the activation of caspases 3 and 9 by these extracts suggests a mitochondria-dependent apoptosis route. However, other routes cannot be ruled out. Together, these results point out the methanol extracts of the brown algae D. mentrualis and D. cilliolata as potential sources of molecules with antitumor activity.

3,3'-Diindolylmethane inhibits the invasion and metastasis of nasopharyngeal carcinoma cells in vitro and in vivo by regulation of epithelial mesenchymal transition

Nasopharyngeal carcinoma (NPC) is characterized by silent progression and atypical early symptoms. Early metastasis to the neck lymph nodes is common. However, conventional chemoradiotherapy is limited and unable to effectively control cervical lymph node metastasis of NPC. In addition, toxicities caused by chemoradiotherapy often induce damage to normal tissues and organs. Thus, the aim of this study was to investigate the ability of 3,3′-diindolylmethane (DIM) to inhibit the invasion and metastasis of NPC cells in vitro and in vivo. The migration and invasive abilities of the 5–8F human NPC cell line were detected using a Transwell assay. Lymph node metastasis in nude mice was observed following the implantation of xenograft tumors for 8 weeks. In addition, western blot analysis was used to detect the expression levels of epithelial mesenchymal transition (EMT)-associated key proteins in NPC cells treated with DIM in vitro and in vivo. The results demonstrated that DIM effectively inhibited the migration and invasion of NPC cells in vitro and the effect was concentration-dependent. In addition, DIM significantly delayed and reduced the occurrence of lymph node metastasis in the animal model. The expression levels of a number of key proteins associated with EMT were affected by DIM treatment. In the animal model, there were no signs of toxicity in the vital organs, including the heart, liver and kidney, of animals fed a diet containing DIM. Therefore, the results of the present study indicate that DIM affects the expression levels of a number of EMT-associated key proteins and induces the inhibition of invasion and metastasis of NPC cells in vitro and in vivo.

Targeted regulation of PI3K/Akt/mTOR/NF-κB signaling by indole compounds and their derivatives: mechanistic details and biological implications for cancer therapy

Indole compounds, found in cruciferous vegetables, are potent anti-cancer agents. Studies with indole-3-carbinol (I3C) and its dimeric product, 3,3'-diindolylmethane (DIM) suggest that these compounds have the ability to deregulate multiple cellular signaling pathways, including PI3K/Akt/mTOR signaling pathway. These natural compounds are also effective modulators of downstream transcription factor NF-κB signaling which might help explain their ability to inhibit invasion and angiogenesis, and the reversal of epithelial-to-mesenchymal transition (EMT) phenotype and drug resistance. Signaling through PI3K/Akt/mTOR and NF-κB pathway is increasingly being realized to play important role in EMT through the regulation of novel miRNAs which further validates the importance of this signaling network and its regulations by indole compounds. Here we will review the available literature on the modulation of PI3K/Akt/mTOR/NF-κB signaling by both parental I3C and DIM, as well as their analogs/derivatives, in an attempt to catalog their anticancer activity.