BRM270, a Compound from Natural Plant Extracts, Inhibits Glioblastoma Stem Cell Properties and Glioblastoma Recurrence

Combined BRM270 and endostatin inhibit relapse of NSCLC while suppressing lung cancer stem cell proliferation induced by endostatin

Endostatin (ES, ENDO) has been reported to suppress the growth of tumors while inducing the proliferation of lung cancer stem cells (LCSCs), causing a poor prognosis for lung cancer. In this study, we aimed to clarify whether BRM270 can inhibit the proliferation of cancer stem cells (CSCs). Endostatin + BRM270 showed anti-tumor effects by reducing tumor volume and increasing survival. Administration of BRM270 reduced the number of aldehyde dehydrogenase-positive (ALDH+) cells and the level of ALDH1A1 expression in tumors by increasing the level of miR-128 while decreasing the levels of BMI-1, ABCC-5, E2F3, and c-MET. The luciferase activity of miR-128 promoter was increased by an increasing concentration of BRM270. In addition, BMI-1, ABCC-5, E2F3, and c-MET were identified as candidate targets of miR-128, and the overexpression of miR-128 significantly reduced mRNA/protein levels of BMI-1, ABCC-5, E2F3, and c-MET in A549 and H460 cells. Administration of BRM270 inhibited the expression of BMI-1, ABCC-5, E2F3, and c-MET in a dose-dependent manner. In this study, we showed for the first time that the combined administration of endostatin and BRM270 achieved anti-tumor effects while suppressing the proliferation of stem cells.

Safrana l Prevents Prostate Cancer Recurrence by Blocking the Re-activation of Quiescent Cancer Cells via Downregulation of S-Phase Kinase-Associated Protein 2

The re-proliferation of quiescent cancer cells is considered to be the primary contributor to prostate cancer (Pca) recurrence and progression. In this study, we investigated the inhibitory effect of safranal, a monoterpene aldehyde isolated from Crocus sativus (saffron), on the re-proliferation of quiescent Pca cells in vitro and in vivo. The results showed that safranal efficiently blocked the re-activation of quiescent Pca cells by downregulating the G₀/G₁ cell cycle regulatory proteins CDK2, CDK4, CDK6, and phospho-Rb at Ser807/811 and elevating the levels of cyclin-dependent kinase inhibitors, p21 and p27. Further investigation on the underlying mechanisms revealed that safranal suppressed the mRNA and protein expression levels of Skp2, possibly through the deregulation of the transcriptional activity of two major transcriptional factors, E2F1 and NF-κB subunits. Moreover, safranal inhibited AKT phosphorylation at Ser473 and deregulated both canonical and non-canonical NF-κB signaling pathways. Safranal suppressed the tumor growth of quiescent Pca cell xenografts in vivo. Furthermore, safranal-treated tumor tissues exhibited a reduction in Skp2, E2F1, NF-κB p65, p-IκBα (Ser32), c-MYC, p-Rb (Ser807), CDK4, CDK6, and CDK2 and an elevation of p27 and p21 protein levels. Therefore, our findings demonstrate that safranal suppresses cell cycle re-entry of quiescent Pca cells in vitro and in vivo plausibly by repressing the transcriptional activity of two major transcriptional activators of Skp2, namely, E2F1 and NF-κB, through the downregulation of AKT phosphorylation and NF-κB signaling pathways, respectively.

Natural Compounds Targeting Cancer Stem Cells: A Promising Resource for Chemotherapy

BACKGROUND

Cancer Stem Cells (CSCs) are the subpopulation of cancer cells which are directly involved in drug resistance, metastases to distant organ and cancer recurrence.

METHODS

A systematic literature search was conducted through various electronic databases including, Pubmed, Scopus, Google scholar using the keywords "cancer stem cells" and "natural compounds" in the present study. Articles published between 1999 and 2019 were reviewed. All the expositions concerning CSCs associated cancer pathogenesis and therapy resistance, as well as targeting these properties of CSCs by natural compounds were selected for the current study.

RESULTS

Natural compounds have always been thought as a rich source of biologically active principles, which target aberrantly activated signaling pathways and other modalities of CSCs, while tethering painful side effects commonly involved in the first-line and second-line chemo-radiotherapies. In this review, we have described the key signaling pathways activated in CSCs to maintain their survival and highlighted how natural compounds interrupt these signaling pathways to minimize therapy resistance, pathogenesis and cancer recurrence properties of CSCs, thereby providing useful strategies to treat cancer or aid in cancer therapy improvement. Like normal stem cells, CSCs rely on different signaling pathways and other properties for their maintenance. Therefore, the success of cancer treatment depends on the development of proper anti-neoplastic drugs capable of intercepting those signaling pathways as well as other properties of CSCs in order to eradicate this evasive subpopulation of cancer cells.

CONCLUSION

Compounds of natural origin might act as an outstanding source to design novel therapies against cancer stem cells.

BRM270 targets cancer stem cells and augments chemo-sensitivity in cancer

Over the past decade, a number of studies have demonstrated the resistance of cancer cells to conventional drugs and have recognized this as a major challenge in cancer therapy. While attempting to understand the underlying mechanisms of chemoresistance, several studies have suggested that the presence of cancer stem cells (CSCs) in tumors is one of the major pathways contributing toward resistance. Chemoresistance leads to cancer treatment failure and worsens the prognosis of patients. Natural herbal compounds are gaining attention as an alternative treatment strategy for cancer. These compounds may be effective against chemoresistant cells either alone or synergistically alongside conventional drugs, sensitizing cancer cells and enhancing the therapeutic efficacy. BRM270 is a natural compound made from seven herbal plant (Saururus chinensis, Citrus unshiu Markovich, Aloe vera, Arnebia euchroma, Portulaca oleracea, Prunella vulgaris var. lilacina and Scutellaria bacicalensis) extracts used in Asian traditional medicine and has the potential to target CSCs. Several studies have demonstrated the positive effects of BRM270 against chemoresistant cancer and its synergy alongside existing cancer drugs, including paclitaxel and gefitinib. These effects have been observed against various cancer types, including resistant non-small cell lung cancer (NSCLC), glioblastoma, multi-drug resistant osteosarcoma, cervical cancer, pancreatic cancer and hepatocarcinoma. The present review discusses the effects of BRM270 treatment against CSC-associated chemoresistance in common types of cancer.

Validation of Enhancing Effects of Curcumin on Radiotherapy with F98/FGT Glioblastoma-Bearing Rat Model

Glioblastoma, the most common and aggressive brain tumor with low survival rate, is difficult to be cured by neurosurgery or radiotherapy. Mounting evidence has reported the anti-inflammatory and anticancer effects of curcumin on several types of cancer in preclinical studies and clinical trials. To our knowledge, there is no platform or system that could be used to effectively and real-timely evaluate the therapeutic efficacy of curcumin for glioblastoma multiforme (GBM). In this study, we constructed a lentivirus vector with triple-reporter genes (Fluc/GFP/tk) and transduced into rat F98 glioblastoma cells to establish an orthotopic F98/FGT glioma-bearing rat model. In the model, the therapeutic efficacies for curcumin alone, radiation alone, and their combination were evaluated via noninvasive bioluminescent imaging and overall survival measurements. At the cell level, curcumin is capable of causing a G2/M cell cycle arrest and sensitizing the F98 cells to radiation. In animal model, curcumin synergistically enhances the effects of radiotherapy on suppressing the growth of both transplanted glioma cells and in situ brain tumors, and extending the overall survival periods longer than those of curcumin alone and radiation alone treatments. In conclusion, we have demonstrated that curcumin may serve as a novel radiosensitizer to combine with radiotherapy using the triple-reporter F98/FGT animal model for effective and simultaneous evaluation of therapeutic efficacy.

Natural Products and Synthetic Analogs as a Source of Antitumor Drugs

Cancer is a heterogeneous disease and one of the major issues of health concern, especially for the public health system globally. Nature is a source of anticancer drugs with abundant pool of diverse chemicals and pharmacologically active compounds. In recent decade, some natural products and synthetic analogs have been investigated for the cancer treatment. This article presents the utilization of natural products as a source of antitumor drugs.

BRM270 Inhibits the Proliferation of CD44 Positive Pancreatic Ductal Adenocarcinoma Cells via Downregulation of Sonic Hedgehog Signaling

Pancreatic cancer has a poor survival rate as compared to other types of cancer. Surface marker CD44 plays important role in epithelial-mesenchymal transition and cancer stem cell phenotype. Therefore, targeting CD44 positive pancreatic cancer cells might enhance therapies effectiveness. Our previous studies indicated the antitumorigenesis effect of BRM270 in osteosarcoma, lung cancer, and glioblastoma; however there is no evidence on BRM270 impacts on pancreatic cancer growth. In this study, we investigated the effect of BRM270 on the isolated CD44 positive pancreatic ductal adenocarcinoma cells (CD44⁺ PDAC). Results showed that CD44 positive cells undergo apoptosis induced by BRM270. Moreover, BRM270 also inhibits stemness and metastasis traits in CD44⁺ PDAC via Sonic hedgehog signaling pathway and SALL4 expression. In vivo study indicated that tumor growth derived from CD44⁺ PDAC was suppressed as daily uptake by BRM270 5 mg/kg. These data suggest the alternative approach in antipancreatic tumorigenesis via herbal plants extract and selectively targeting CD44⁺ PDAC cells in tumor.

The Molecular Mechanisms of Plant-Derived Compounds Targeting Brain Cancer

Glioblastoma multiforme (GBM) is one of the most aggressive and malignant forms of brain tumors. Despite recent advances in operative and postoperative treatments, it is almost impossible to perform complete resection of these tumors owing to their invasive and diffuse nature. Several natural plant-derived products, however, have been demonstrated to have promising therapeutic effects, such that they may serve as resources for anticancer drug discovery. The therapeutic effects of one such plant product, n-butylidenephthalide (BP), are wide-ranging in nature, including impacts on cancer cell apoptosis, cell cycle arrest, and cancer cell senescence. The compound also exhibits a relatively high level of penetration through the blood-brain barrier (BBB). Taken together, its actions have been shown to have anti-proliferative, anti-chemoresistance, anti-invasion, anti-migration, and anti-dissemination effects against GBM. In addition, a local drug delivery system for the subcutaneous and intracranial implantation of BP wafers that significantly reduce tumor size in xenograft models, as well as orthotopic and spontaneous brain tumors in animal models, has been developed. Isochaihulactone (ICL), another kind of plant product, possesses a broad spectrum of pharmacological activities, including impacts on cancer cell apoptosis and cell cycle arrest, as well as anti-proliferative and anti-chemoresistance effects. Furthermore, these actions have been specifically shown to have cancer-fighting effects on GBM. In short, the results of various studies reviewed herein have provided substantial evidence indicating that BP and ICH are promising novel anticancer compounds with good potential for clinical applications.