Alantolactone inhibits stem-like cell phenotype, chemoresistance and metastasis in PC3 cells through STAT3 signaling pathway

Alantolactone enhances the sensitivity of melanoma to MAPK pathway inhibitors by targeting inhibition of STAT3 activation and down-regulating stem cell markers

Mitogen-activated protein kinase inhibitors (MAPKi) were the first line drugs for advanced melanoma patients with BRAF mutation. Targeted therapies have significant therapeutic effects; however, drug resistance hinders their long-term efficacy. Therefore, the development of new therapeutic strategies against MAPKi resistance is critical. Our previous results showed that MAPKi promote feedback activation of STAT3 signaling in BRAF-mutated cancer cells. Studies have shown that alantolactone inhibited the activation of STAT3 in a variety of tumor cells. Our results confirmed that alantolactone suppressed cell proliferation and promoted apoptosis by inhibiting STAT3 feedback activation induced by MAPKi and downregulating the expression of downstream Oct4 and Sox2. The inhibitory effect of alantolactone combined with a MAPKi on melanoma cells was significantly stronger than that on normal cells. In vivo and in vitro experiments showed that combination treatment was effective against drug-resistant melanomas. Our research indicates a potential novel combination therapy (alantolactone and MAPKi) for patients with BRAF-mutated melanoma.

Cordycepin Enhanced Therapeutic Potential of Gemcitabine against Cholangiocarcinoma via Downregulating Cancer Stem-Like Properties

Cordycepin, a valuable bioactive component isolated from Cordyceps militaris, has been reported to possess anti-cancer potential and the property to enhance the effects of chemotherapeutic agents in various types of cancers. However, the ability of cordycepin to chemosensitize cholangiocarcinoma (CCA) cells to gemcitabine has not yet been evaluated. The current study was performed to evaluate the above, and the mechanisms associated with it. The study analyzed the effects of cordycepin in combination with gemcitabine on the cancer stem-like properties of the CCA SNU478 cell line, including its anti-apoptotic, migratory, and antioxidant effects. In addition, the combination of cordycepin and gemcitabine was evaluated in the CCA xenograft model. The cordycepin treatment significantly decreased SNU478 cell viability and, in combination with gemcitabine, additively reduced cell viability. The cordycepin and gemcitabine co-treatment significantly increased the Annexin V+ population and downregulated B-cell lymphoma 2 (Bcl-2) expression, suggesting that the decreased cell viability in the cordycepin+gemcitabine group may result from an increase in apoptotic death. In addition, the cordycepin and gemcitabine co-treatment significantly reduced the migratory ability of SNU478 cells in the wound healing and trans-well migration assays. It was observed that the cordycepin and gemcitabine cotreatment reduced the CD44highCD133high population in SNU478 cells and the expression level of sex determining region Y-box 2 (Sox-2), indicating the downregulation of the cancer stem-like population. Cordycepin also enhanced oxidative damage mediated by gemcitabine in MitoSOX staining associated with the upregulated Kelch like ECH Associated Protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) expression ratio. In the SNU478 xenograft model, co-administration of cordycepin and gemcitabine additively delayed tumor growth. These results indicate that cordycepin potentiates the chemotherapeutic property of gemcitabine against CCA, which results from the downregulation of its cancer-stem-like properties. Hence, the combination therapy of cordycepin and gemcitabine may be a promising therapeutic strategy in the treatment of CCA.

Terpenoid-Mediated Targeting of STAT3 Signaling in Cancer: An Overview of Preclinical Studies

Cancer has become one of the most multifaceted and widespread illnesses affecting human health, causing substantial mortality at an alarming rate. After cardiovascular problems, the condition has a high occurrence rate and ranks second in terms of mortality. The development of new drugs has been facilitated by increased research and a deeper understanding of the mechanisms behind the emergence and advancement of the disease. Numerous preclinical and clinical studies have repeatedly demonstrated the protective effects of natural terpenoids against a range of malignancies. Numerous potential bioactive terpenoids have been investigated in natural sources for their chemopreventive and chemoprotective properties. In practically all body cells, the signaling molecule referred to as signal transducer and activator of transcription 3 (STAT3) is widely expressed. Numerous studies have demonstrated that STAT3 regulates its downstream target genes, including Bcl-2, Bcl-xL, cyclin D1, c-Myc, and survivin, to promote the growth of cells, differentiation, cell cycle progression, angiogenesis, and immune suppression in addition to chemotherapy resistance. Researchers viewed STAT3 as a primary target for cancer therapy because of its crucial involvement in cancer formation. This therapy primarily focuses on directly and indirectly preventing the expression of STAT3 in tumor cells. By explicitly targeting STAT3 in both in vitro and in vivo settings, it has been possible to explain the protective effect of terpenoids against malignant cells. In this study, we provide a complete overview of STAT3 signal transduction processes, the involvement of STAT3 in carcinogenesis, and mechanisms related to STAT3 persistent activation. The article also thoroughly summarizes the inhibition of STAT3 signaling by certain terpenoid phytochemicals, which have demonstrated strong efficacy in several preclinical cancer models.

The Molecular Biology of Prostate Cancer Stem Cells: From the Past to the Future

Prostate cancer (PCa) continues to rank as the second leading cause of cancer-related mortality in western countries, despite the golden treatment using androgen deprivation therapy (ADT) or anti-androgen therapy. With decades of research, scientists have gradually realized that the existence of prostate cancer stem cells (PCSCs) successfully explains tumor recurrence, metastasis and therapeutic failure of PCa. Theoretically, eradication of this small population may improve the efficacy of current therapeutic approaches and prolong PCa survival. However, several characteristics of PCSCs make their diminishment extremely challenging: inherent resistance to anti-androgen and chemotherapy treatment, over-activation of the survival pathway, adaptation to tumor micro-environments, escape from immune attack and being easier to metastasize. For this end, a better understanding of PCSC biology at the molecular level will definitely inspire us to develop PCSC targeted approaches. In this review, we comprehensively summarize signaling pathways responsible for homeostatic regulation of PCSCs and discuss how to eliminate these fractional cells in clinical practice. Overall, this study deeply pinpoints PCSC biology at the molecular level and provides us some research perspectives.

STAT3 signaling in prostate cancer progression and therapy resistance: An oncogenic pathway with diverse functions

The categorization of cancers demonstrates that prostate cancer is the most common malignancy in men and it causes high death annually. Prostate cancer patients are diagnosed mainly via biomarkers such as PSA test and patients show poor prognosis. Prostate cancer cells rapidly diffuse into different parts of body and their metastasis is also a reason for death. Current therapies for prostate cancer patients include chemotherapy, surgery and radiotherapy as well as targeted therapy. The progression of prostate cancer cells is regulated by different factors that STAT3 signaling is among them. Growth factors and cytokines such as IL-6 can induce STAT3 signaling and it shows carcinogenic impact. Activation of STAT3 signaling occurs in prostate cancer and it promotes malignant behavior of tumor cells. Induction of STAT3 signaling increases glycolysis and proliferation of prostate cancer cells and prevents apoptosis. Furthermore, STAT3 signaling induces EMT mechanism in increasing cancer metastasis. Activation of STAT3 signaling stimulates drug resistance and the limitation of current works is lack of experiment related to role of STAT3 signaling in radio-resistance in prostate tumor. Calcitriol, capsazepine and β-elemonic are among the compounds capable of targeting STAT3 signaling and its inhibition in prostate cancer therapy. In addition to natural products, small molecules targeting STAT3 signaling have been developed in prostate cancer therapy.

Antiproliferative activity of CD44 siRNA-PEI-PEG nanoparticles in glioblastoma: involvement of AKT signaling

Background and purpose

Glioblastoma multiforme (GBM) is the most invasive type of cancer which starts inside the brain. GBM cells were found to have similar properties to glioblastoma cancer stem cells. CD44 can be used as a marker of the cancer stem cells in a subset of glioblastoma tumor cells. Recent studies showed that CD44 is involved in developing cancer cells via the protein kinase B (PKB or AKT) signaling pathway. Therefore, this study aimed to investigate the CD44 mRNA silencing effects on the glioblastoma cell cycle via AKT signaling pathway.

Experimental approach

To determine CD44 expression in the samples of the patients with GBM, we used the analysis of data extracted from TCGA database. qRT-PCR and western blotting were used to evaluate the expression level of genes and proteins. Different cell cycles were evaluated by DAPI staining and flow cytometry.

Findings/Results

Bioinformatics results showed that CD44 expression level in GBM tumor samples is higher than in normal samples. Effects of poly (ethylene imine)-polyethylene glycol (PEI-PEG)-loaded CD44 siRNA in cell cycle showed that CD44 silencing could inhibit cell cycle in G0-G1 phase by more than 20% compared to the negative control (P < 0.05). Furthermore, PEI-PEG-loaded CD44 siRNA reduces the expression of cyclin D1 and CKD-4. According to our findings, this structure also prevented AKT phosphorylation at Thr-308 and Ser-473.

Conclusion and implications

Our results suggest that PEI-PEG-loaded CD44 siRNA may attenuate the cell cycle by suppressing AKT signaling pathway.

Alantolactone: A sesquiterpene lactone with diverse pharmacological effects

Alantolactone (Ala) is a sesquiterpene lactone that can be isolated from many herbal plants belonging to Asteraceae. Besides the antimicrobial activities against bacteria, fungi and viruses, Ala has also demonstrated significant anti-inflammatory effects in various models by inhibiting NF-κB and MAPKs to decrease the pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. The antitumor effects of Ala have been demonstrated in vitro and in vivo via inducing intrinsic apoptosis, oxidative stress, ER stress, cell cycle arrest and inhibiting autophagy and STAT3 phosphorylation, which are also involved in its combination or synergy with other antitumor drugs. Ala also has neuroprotective activity through attenuating oxidative stress and inflammation, besides its modulation of glucose and lipid metabolism. This review summarizes the recent advances of the pharmacological effects of Ala, including anti-inflammatory, antitumor, antimicrobial, neuroprotective activities, as well as the underlying mechanisms. Ala might be employed as a potential lead to develop drugs for multiple diseases.