STAT3 enhances radiation-induced tumor migration, invasion and stem-like properties of bladder cancer

Cryptotanshinone Suppresses the STAT3/BCL-2 Pathway to Provoke Human Bladder Urothelial Carcinoma Cell Death

Bladder cancer is one of the most common human malignancies worldwide. Aberrant activation of signal transducer and activator of transcription 3 (STAT3) is crucial to driving malignant progression and predicting poor prognosis of multiple human cancers, including bladder cancer, making STAT3 a promising target of cancer therapeutics. Cryptotanshinone (CTS) is an anticancer ingredient of Danshen ( Salvia miltiorrhiza ), a top-graded Chinese medicinal herb. However, whether CTS targets STAT3 to exert its cytotoxic effect on human bladder cancer remains unknown. Herein, we demonstrated that CTS is cytotoxic to multiple human urinary bladder transitional cell carcinoma (TCC) cell lines while sparing normal human urothelial cells. CTS provoked apoptosis-dependent bladder TCC cytotoxicity, as apoptosis blockage by z-VAD-fmk markedly rescued the clonogenicity of CTS-treated cells. Besides, CTS was found to suppress constitutive and interleukin 6-inducible activation of STAT3, evidenced by the downregulation of STAT3 tyrosine 705 phosphorylation and BCL2, a recognized STAT3 transcriptional target. Notably, ectopic expression of a dominant-active STAT3 mutant (STAT3-C) or BCL-2 alleviated CTS-induced apoptosis and clonogenicity inhibition, thus confirming STAT3 blockade as a pivotal mechanism of CTS's cytotoxic action on bladder TCC cells. Lastly, immunoblotting revealed that CTS lowered the levels of active JAK2, an upstream kinase that mediates STAT3 tyrosine 705 phosphorylation. Altogether, we conclude that the blockade of the JAK2/STAT3/BCL-2 antiapoptotic signaling axis is a vital mechanism whereby CTS provokes bladder cancer cytotoxicity. The current evidence implicates CTS's potential to be translated into a bladder cancer therapeutic agent.

Key immune cells and their crosstalk in the tumor microenvironment of bladder cancer: insights for innovative therapies

Bladder cancer (BC) is a heterogeneous disease associated with high mortality if not diagnosed early. BC is classified into non-muscle-invasive BC (NMIBC) and muscle-invasive BC (MIBC), with MIBC linked to poor systemic therapy response and high recurrence rates. Current treatments include transurethral resection with Bacillus Calmette-Guérin (BCG) therapy for NMIBC and radical cystectomy with chemotherapy and/or immunotherapy for MIBC. The tumor microenvironment (TME) plays a critical role in cancer progression, metastasis, and therapeutic efficacy. A comprehensive understanding of the TME's complex interactions holds substantial translational significance for developing innovative treatments. The TME can contribute to therapeutic resistance, particularly in immune checkpoint inhibitor (ICI) therapies, where resistance arises from tumor-intrinsic changes or extrinsic TME factors. Recent advancements in immunotherapy highlight the importance of translational research to address these challenges. Strategies to overcome resistance focus on remodeling the TME to transform immunologically "cold" tumors, which lack immune cell infiltration, into "hot" tumors that respond better to immunotherapy. These strategies involve disrupting cancer-microenvironment interactions, inhibiting angiogenesis, and modulating immune components to enhance anti-tumor responses. Key mechanisms include cytokine involvement [e.g., interleukin-6 (IL-6)], phenotypic alterations in macrophages and natural killer (NK) cells, and the plasticity of cancer-associated fibroblasts (CAFs). Identifying potential therapeutic targets within the TME can improve outcomes for MIBC patients. This review emphasizes the TME's complexity and its impact on guiding novel therapeutic approaches, offering hope for better survival in MIBC.

Enhancement of radio-sensitivity by inhibition of Janus kinase signaling with oclacitinib in canine tumor cell lines

A combination of irradiation and oclacitinib, a Janus kinase (JAK) inhibitor used in dogs, could lead to synergistic anticancer effects in canine tumors. However, the anti-tumor effects of oclacitinib remain unclear. This study investigated the radio-sensitizing effect of oclacitinib in canine tumors and determined its underlying mechanisms using osteosarcoma (HMPOS), malignant melanoma (CMeC), and thyroid adenocarcinoma (CTAC) cell lines. A clonogenic assay and a tumor growth assessment in a xenograft mouse model (BALB/cAJcl-nu/nu) were performed to evaluate the radio-sensitizing effects of oclacitinib. Oclacitinib enhanced the radio-sensitivity of tumor cells both in vitro and in vivo. The signal transducer and activator of transcription (STAT)3 expression was activated and suppressed by oclacitinib in X-irradiation-exposed cells. Oclacitinib enhanced radiation-induced apoptosis only in HMPOS cells by inhibiting anti-apoptotic genes. In addition, oclacitinib inhibited the transcription of cell-cycle-regulating genes and arrested cell cycle progression from the G1 phase to subsequent phases. In conclusion, oclacitinib enhanced radio-sensitivity both in vitro and in vivo by triggering apoptosis and impeding cell cycle progression via STAT3 inhibition in canine tumor cell lines. This study suggested the clinical therapeutic potential of oclacitinib and radiation therapy in enhancing treatment efficacy and outcomes in canine tumors.

Blockade of the STAT3/BCL-xL Axis Leads to the Cytotoxic and Cisplatin-Sensitizing Effects of Fucoxanthin, a Marine-Derived Carotenoid, on Human Bladder Urothelial Carcinoma Cells

Bladder cancer is a globally prevalent urological malignancy, with transitional carcinoma (TCC) representing the majority of cases. Cisplatin is the primary drug for metastatic bladder cancer chemotherapy; however, its application is limited by nephrotoxicity and resistance. Signal Transducer and Activator of Transcription 3 (STAT3) is an oncogenic transcription factor often overactivated in various cancers, making it an appealing drug target. Fucoxanthin, a marine carotenoid, has significant anticancer properties. This study explored Fucoxanthin's cytotoxic effects and its potential to potentiate the efficacy of Cisplatin, along with the mechanisms underlying these effects, on human bladder TCC cells. We demonstrated that Fucoxanthin is cytotoxic to bladder TCC cells by inducing apoptosis, evidenced by z-VAD-fmk-mediated annulment of Fucoxanthin's cytotoxicity. Furthermore, Fucoxanthin reduced the levels of inherent or interleukin-6-induced tyrosine 705-phosphorylated STAT3 accompanied by downregulating BCL-xL, a well-established STAT3 target. Notably, ectopic expression of STAT3-C, a dominant-active STAT3 mutant, or BCL-xL thwarted Fucoxanthin's proapoptotic and cytotoxic actions. Moreover, Fucoxanthin at subtoxic dosages enhanced the susceptibility to Cisplatin-induced apoptosis of bladder TCC cells initially resistant to Cisplatin. Remarkably, this Cisplatin-sensitizing effect of Fucoxanthin was abrogated when cells ectopically expressed STAT3-C or BCL-xL. Overall, for the first time, we proved that the proapoptotic, cytotoxic, and Cisplatin-sensitizing effects of Fucoxanthin on human bladder TCC cells are attributed to the blockade of the STAT3/BCL-xL axis. Our findings highlight that targeting the STAT3/BCL-xL axis is a promising strategy to eliminate bladder TCC cells and facilitate Cisplatin sensitization, and further support the potential of incorporating Fucoxanthin into Cisplatin-based chemotherapy for treating bladder cancer.

Taraxasterol enhanced bladder cancer cells radiosensitivity via inhibiting the COX-2/PGE2/JAK2/STAT3/MMP pathway

PURPOSE

Radiotherapy with bladder preservation is highly acceptable among patients bearing bladder cancer (BCa), but the occurrence of secondary tolerance (ARR) during treatment is one of the important reasons for the failure of clinical radiotherapy. COX-2 has been frequently reported to be highly expressed and associated with radio-resistance in various cancers. In this study, the feasibility of Taraxasterol (Tara) as a radiosensitizer was investigated, and the target effect of Tara on COX-2 and its underlying mechanism were explored.

METHODS AND MATERIALS

The toxicity of Tara toward BCa cells was detected with the MTT method and cells in response to IR or Tara + IR were compared by clone formation assay. Next, a small RNA interference system (siRNA) was employed to decrease endogenous COX-2 expression in BCa cells, and the stem cell-like features and motion abilities of BCa cells under different treatments were investigated using microsphere formation and transwell chamber assay, respectively. Meanwhile, the expression of a series of inflammation-related molecules and stem cell characteristic molecules was determined by qRT-PCR, western blot and ELISA method. In vivo studies, BCa cells were subcutaneously injected into the right flank of each male mouse. Those mice were then grouped and exposed to different treatment: Tara, IR, IR + Tara and untreated control. The volumes of each tumor were measured every two days and target proteins were detected with immunohistochemical (IHC) staining.

RESULTS

The results show that COX-2 decline, due to COX-2 knocking-down or Tara treatment, could greatly enhance BCa cells' radiosensitivity and significantly decrease their migration, invasion and microsphere formation abilities, companied with the reduce of JAK2, phos-STAT3, MMP2 and MMP9 expression. However, Tara could not further reduce the expression of an above molecule of cells in COX-2-deficient BCa cells. Correspondingly, Tara treatment could not further enhance those siCOX-2 BCa cells response to IR.

CONCLUSIONS

Our data support that Tara can improve the radiosensitivity of BCa cells by targeting COX-2/PGE2. The mechanism may involve regulating STAT3 phosphorylation, DNA damage response protein activation, and expression of MMP2/MMP9.

Targeted therapies in bladder cancer: signaling pathways, applications, and challenges

Bladder cancer (BC) is one of the most prevalent malignancies in men. Understanding molecular characteristics via studying signaling pathways has made tremendous breakthroughs in BC therapies. Thus, targeted therapies including immune checkpoint inhibitors (ICIs), antibody-drug conjugates (ADCs), and tyrosine kinase inhibitor (TKI) have markedly improved advanced BC outcomes over the last few years. However, the considerable patients still progress after a period of treatment with current therapeutic regimens. Therefore, it is crucial to guide future drug development to improve BC survival, based on the molecular characteristics of BC and clinical outcomes of existing drugs. In this perspective, we summarize the applications and benefits of these targeted drugs and highlight our understanding of mechanisms of low response rates and immune escape of ICIs, ADCs toxicity, and TKI resistance. We also discuss potential solutions to these problems. In addition, we underscore the future drug development of targeting metabolic reprogramming and cancer stem cells (CSCs) with a deep understanding of their signaling pathways features. We expect that finding biomarkers, developing novo drugs and designing clinical trials with precisely selected patients and rationalized drugs will dramatically improve the quality of life and survival of patients with advanced BC.

Noncoding RNAs as regulators of STAT3 pathway in gastrointestinal cancers: Roles in cancer progression and therapeutic response

Gastrointestinal (GI) tumors (cancers of the esophagus, gastric, liver, pancreas, colon, and rectum) contribute to a large number of deaths worldwide. STAT3 is an oncogenic transcription factor that promotes the transcription of genes associated with proliferation, antiapoptosis, survival, and metastasis. STAT3 is overactivated in many human malignancies including GI tumors which accelerates tumor progression, metastasis, and drug resistance. Research in recent years demonstrated that noncoding RNAs (ncRNAs) play a major role in the regulation of many signaling pathways including the STAT3 pathway. The major types of endogenous ncRNAs that are being extensively studied in oncology are microRNAs, long noncoding RNAs, and circular RNAs. These ncRNAs can either be tumor-promoters or tumor-suppressors and each one of them imparts their activity via different mechanisms. The STAT3 pathway is also tightly modulated by ncRNAs. In this article, we have elaborated on the tumor-promoting role of STAT3 signaling in GI tumors. Subsequently, we have comprehensively discussed the oncogenic as well as tumor suppressor functions and mechanism of action of ncRNAs that are known to modulate STAT3 signaling in GI cancers.

DAB2IP-knocking down resulted in radio-resistance of breast cancer cells is associated with increased hypoxia and vasculogenic mimicry formation

PURPOSE

As a part of breast-conserving therapy (BCT), postoperative radiotherapy is one of the main means to improve the clinical efficacy of breast cancer (BCa). However, ionizing radiation (IR) may induce BCa cells to develop radioresistance, which causes tumor recurrence and metastasis after treatment. Recently, DOC-2/DAB2 interactive protein (DAB2IP) has been reported often down-regulated in a variety of cancers and is related to tumor tolerance to radiotherapy. In this study, BCa cell lines were introduced to study how DAB2IP deficient influenced BCa cell radiosensitivity in vitro and in vivo and discuss the possible mechanism.

METHODS AND MATERIALS

Small RNA interference system (siRNA) was employed to decrease DAB2IP expression in two BCa cell lines, MDA-MB-231 and 4T1. Cells in response to IR or antineoplastics were detected by clone formation assay or MTT method, respectively. For in vivo studies, siDAB2IP or siControl cells were subcutaneously injected into the right flank of each female mouse. Sphere formation assay, soft agar colony anchoring assay and in vivo tumorigenesis assay were implemented to examine the stem cell-like features of BCa cells. Tube formation assay as well as immunofluorescence assay (IFA) were respectively applied to determine the angiogenesis of tumor cells in vitro and in vivo. The expression of a series of angiogenesis-related molecules was analyzed by qRT-PCR, western blot and IFA.

RESULTS

It was observed that the downregulation of DAB2IP could significantly improve the clone formation ability of BCa cells, reduce their sensitivity to radiation and chemotherapy drugs, enhance their migration and invasion abilities and increase their stemness characteristics. It was also noted that either DAB2IP-knocking down or treated with the conditioned medium from DAB2IP-deficient BCa cells could promote the tube-forming ability of the endothelial cell. Similarly, in vivo studies showed that tumors developed from siDAB2IP BCa cells had higher tumor microvascular density (MVD) and more severe oxygen deficiency than that in DAB2IP- sufficient tumors. Meanwhile, Knock-down of DAB2IP inhibited vascular maturation and promoted the formation of vasculogenic mimicry (VM) in BCa tissues. Down-regulation of STAT3 could enhance siDAB2IP cells sensitivity to IR, accompanied by the decrease of VEGF expression.

CONCLUSIONS

Our data support that loss of DAB2IP confers radio-resistance of BCa could be due to increased hypoxia, inhibited vascular maturation and promoted VM formation. STAT3 inhibition could be a potential way to overcome such DAB2IP-deficient induced tolerance in BCT.

Inhibitory effects of total triterpenoids isolated from the Hedyotis diffusa willd on H1975 cells

It is estimated that non-small-cell lung cancer (NSCLC) is responsible for 80% of human deaths related to lung cancer worldwide. Currently, it has been discovered that two transcription factors. Nuclear factor-κB (NF-κB) and Signal transducer and activator of transcription 3 (STAT3) were the main factors affecting inflammation and cancer, and their activation promoted lung cancer cell proliferation. Hedyotis diffusa Willd. (H. diffusa) is an herbal Chinese medicine, which has always been used for the treatment of malignant tumors in clinical. Previous research found that H. diffusa could inhibit the proliferation of H1975 cells, but the specific mechanisms remain elusive. We investigated the effects of total triterpenes extracted from H. diffusa (TTH) on the migration, proliferation and apoptosis of H1975 cells. Cell-cycle and immunofluorescence analysis showed that TTH could block H1975 cells at G0/G1 phase and induce apoptosis of experimental cells. The protein levels of Bcl-2 were decreased, while the levels of pro-apoptotic Bax were increased. In addition, TTH could also inhibit the migration of H1975 cells through downregulated MMP-2 and MMP-9 and upregulated TIMP-2. Further research found that the level of phospho-STAT3 was significantly decreased after administration of TTH. And protein expression level of NF-κB in nucleus was decreased after TTH treatment, while NF-κB in cytoplasm increased. These results suggested that TTH could inhibit the proliferation and migration of H1975 cells, and also could induce cell apoptosis. These effects were closely connected to the activation of NF-κB and the phosphorylation of STAT3.

Renieramycin T Inhibits Melanoma B16F10 Cell Metastasis and Invasion via Regulating Nrf2 and STAT3 Signaling Pathways

As one of marine tetrahydroisoquinoline alkaloids, renieramycin T plays a significant role in inhibiting tumor metastasis and invasion. However, the effect of renieramycin T on inflammation-related tumor metastasis and invasion is still unknown, and its mechanisms remain unclear. Here we established an inflammation-related tumor model by using the supernatant of RAW264.7 cells to simulate B16F10 mouse melanoma cells. The results indicate that renieramycin T suppressed RAW264.7 cell supernatant-reduced B16F10 cell adhesion to a fibronectin-coated substrate, migration, and invasion through the matrigel in a concentration-dependent manner. Moreover, Western blot results reveal that renieramycin T attenuated the phosphorylation of STAT3 and down-regulated the expression of Nrf2. Together, the above findings suggest a model of renieramycin T in suppressing B16F10 cancer cell migration and invasion. It may serve as a promising drug for the treatment of cancer metastasis.

Bacteria−Based Synergistic Therapy in the Backdrop of Synthetic Biology

Although the synergistic effect of traditional therapies combined with tumor targeting or immunotherapy can significantly reduce mortality, cancer remains the leading cause of disease related death to date. Limited clinical response rate, drug resistance and off-target effects, to a large extent, impede the ceilings of clinical efficiency. To get out from the dilemmas mentioned, bacterial therapy with a history of more than 150 years regained great concern in recent years. The rise of biological engineering and chemical modification strategies are able to optimize tumor bacterial therapy in highest measure, and meanwhile avoid its inherent drawbacks toward clinical application such as bacteriotoxic effects, weak controllability, and low security. Here, we give an overview of recent studies with regard to bacteria-mediated therapies combined with chemotherapy, radiotherapy, and immunotherapy. And more than that, we review the bacterial detoxification and targeting strategies via biological reprogramming or chemical modification, their applications, and clinical transformation prospects.

EZH2 targeting to improve the sensitivity of acquired radio-resistance bladder cancer cells

Among the many treatments for Bladder cancer (BCa) patients, radiotherapy is an effective way to preserve the bladder. However, as the frequency of irradiation increases, the tumor cells appear "acquired radio-resistance" (ARR) and loss the sensitivity to radiotherapy. To explore the molecular mechanism of ARR, two BCa cell lines, 5637 and T24, were enrolled here and their ARR counterparts, 5637R and T24R, were obtained by exposure to γ-ray of 2 Gy for 30 times. Compared to parental cells, ARR cells have significantly enhanced stem cell-like phenotype, robust DNA damage repair capabilities and elevated expression of zeste homolog 2 (EZH2). Decreasing EZH2 expression, both parental and ARR cells exhibited reduced abilities of forming microsphere and repairing DNA damage, but enhanced cells radio-sensitivity and intracellular autophagy compared to untreated cells. Down-regulation the expression of EZH2 induced an increasing of both LC3 and P62 in parental cells, while in ARR cells, only LC3 increased upon EZH2 reduction. On the other hand, UNC1999 treatment caused the increasing of LC3B and P62 in all cells, suggested that siEZH2 and UNC1999 affect ARR cells autophagy through different mechanisms. In vivo study showed that pre-treated with UNC1999 greatly enhanced T24R cells sensitivity to IR, and knocking down the expression of EZH2 significantly suppressed the tumor growth. Combined with bioinformatics data analysis, we speculate that EZH2 is an important biomolecule linking the diagnosis, radiotherapy and prognosis of BCa. EZH2 targeted therapy may be an effective way to overcome ARR of BCa, and is worthy of in-depth study.