Stat3-siRNA inhibits the growth of gastric cancerin vitroandin vivo

siRNA-based therapy for gastric adenocarcinoma: what's next step?

Gastric cancer continues to have a high death rate despite advancements in their diagnosis and treatment. Novel treatment techniques are thus desperately needed. This is where double-stranded RNA molecules known as small interfering RNA (siRNA), which may selectively target the mRNA of disease-causing genes, may find use in medicine. For siRNAs to function properly in the human body, they must be shielded from deterioration. Furthermore, in order to maintain organ function, they must only target the tumor and spare normal tissue. siRNAs have been designed using clever delivery mechanisms including polymers and lipids to achieve these objectives. Although siRNA protection is not hard to acquire, it is still challenging to target cancer cells with them. Here, we first discuss the basic characteristics of gastric cancer before describing the properties of siRNA and typical delivery methods created specifically for gastric tumors. Lastly, we provide a succinct overview of research using siRNAs to treat gastric tumors.

Enhancing cancer therapy: The role of drug delivery systems in STAT3 inhibitor efficacy and safety

The signal transducer and activator of transcription 3 (STAT3), a member of the STAT family, resides in the nucleus to regulate genes essential for vital cellular functions, including survival, proliferation, self-renewal, angiogenesis, and immune response. However, continuous STAT3 activation in tumor cells promotes their initiation, progression, and metastasis, rendering STAT3 pathway inhibitors a promising avenue for cancer therapy. Nonetheless, these inhibitors frequently encounter challenges such as cytotoxicity and suboptimal biocompatibility in clinical trials. A viable strategy to mitigate these issues involves delivering STAT3 inhibitors via drug delivery systems (DDSs). This review delineates the regulatory mechanisms of the STAT3 signaling pathway and its association with cancer. It offers a comprehensive overview of the current application of DDSs for anti-STAT3 inhibitors and investigates the role of DDSs in cancer treatment. The conclusion posits that DDSs for anti-STAT3 inhibitors exhibit enhanced efficacy and reduced adverse effects in tumor therapy compared to anti-STAT3 inhibitors alone. This paper aims to provide an outline of the ongoing research and future prospects of DDSs for STAT3 inhibitors. Additionally, it presents our insights on the merits and future outlook of DDSs in cancer treatment.

Advances in RNAi therapies for gastric cancer: Targeting drug resistance and nanoscale delivery

Gastric cancer poses a significant health challenge, and exploring innovative therapeutic strategies is imperative. RNA interference (RNAi) has employed as an important therapeutic strategy for diseases by selectively targeting key pathways involved in diseases pathogenesis. Small interfering RNA (siRNA), a potent RNAi tool, possesses the capability to silence genes and downregulate their expression. This review provides a comprehensive examination of the potential applications of small interfering RNA (siRNA) and short hairpin RNA (shRNA), supplemented by an in-depth analysis of nanoscale delivery systems, in the context of gastric cancer treatment. The potential of siRNA to markedly diminish the proliferation and invasion of gastric cancer cells through the modulation of critical molecular pathways, including PI3K, Akt, and EMT, is highlighted. Besides, siRNA demonstrates its efficacy in inducing chemosensitivity in gastric tumor cells, thus impeding tumor progression. However, the translational potential of unmodified siRNA faces challenges, particularly in vivo and during clinical trials. To address this, we underscore the pivotal role of nanostructures in facilitating the delivery of siRNA to gastric cancer cells, effectively suppressing their progression and enhancing gene silencing efficiency. These siRNA-loaded nanoparticles exhibit robust internalization into gastric cancer cells, showcasing their potential to significantly reduce tumor progression. The translation of these findings into clinical trials holds promise for advancing the treatment of gastric cancer patients.

Oligonucleotide-Based Therapeutics for STAT3 Targeting in Cancer-Drug Carriers Matter

High expression and phosphorylation of signal transducer and transcription activator 3 (STAT3) are correlated with progression and poor prognosis in various types of cancer. The constitutive activation of STAT3 in cancer affects processes such as cell proliferation, apoptosis, metastasis, angiogenesis, and drug resistance. The importance of STAT3 in cancer makes it a potential therapeutic target. Various methods of directly and indirectly blocking STAT3 activity at different steps of the STAT3 pathway have been investigated. However, the outcome has been limited, mainly by the number of upstream proteins that can reactivate STAT3 or the relatively low specificity of the inhibitors. A new branch of molecules with significant therapeutic potential has emerged thanks to recent developments in the regulatory function of non-coding nucleic acids. Oligonucleotide-based therapeutics can silence target transcripts or edit genes, leading to the modification of gene expression profiles, causing cell death or restoring cell function. Moreover, they can reach untreatable targets, such as transcription factors. This review briefly describes oligonucleotide-based therapeutics that found application to target STAT3 activity in cancer. Additionally, this review comprehensively summarizes how the inhibition of STAT3 activity by nucleic acid-based therapeutics such as siRNA, shRNA, ASO, and ODN-decoy affected the therapy of different types of cancer in preclinical and clinical studies. Moreover, due to some limitations of oligonucleotide-based therapeutics, the importance of carriers that can deliver nucleic acid molecules to affect the STAT3 in cancer cells and cells of the tumor microenvironment (TME) was pointed out. Combining a high specificity of oligonucleotide-based therapeutics toward their targets and functionalized nanoparticles toward cell type can generate very efficient formulations.

Role of STAT3 in the initiation, progression, proliferation and metastasis of breast cancer and strategies to deliver JAK and STAT3 inhibitors

INTRODUCTION

Breast cancer (BC) accounts for the majority of cancers among the female population. Anomalous activation of various signaling pathways has become an issue of concern. The JAK-STAT signaling pathway is activated in numerous cancers, including BC. STAT3 is widely involved in BCs, as 40 % of BCs display phosphorylated STAT3. JAK-STAT signaling is crucial for proliferation, survival, metastasis and other cellular events associated with the tumor microenvironment. Hence, targeting this pathway has become an area of interest among researchers.

KEY FINDINGS

This review article focuses on the role of STAT3 in the initiation, proliferation, progression and metastasis of BC. The roles of various phytochemicals, synthetic molecules and biologicals against JAK-STAT and STAT3 in various cancers have been discussed, with special emphasis on BC.

SIGNIFICANCE

JAK and STAT3 are involved in various phases from initiation to metastasis, and targeting this pathway is a promising approach to inhibit the various stages of BC development and to prevent metastasis. A number of phytochemicals and synthetic and biological molecules have demonstrated potential inhibitory effects on JAK and STAT3, thereby paving the way for the development of better therapeutics against BC.

Corilagin exhibits differential anticancer effects through the modulation of STAT3/5 and MAPKs in human gastric cancer cells

Corilagin (CLG) is a hydrolyzable tannin and possesses various pharmacological activities. Here, we investigated the impact of CLG as an anti-tumor agent against human gastric tumor cells. We observed that CLG could cause negative regulation of JAKs-Src-STAT3/5 signaling axis in SNU-1 cells, but did not affect these pathways in SNU-16 cells. Interestingly, CLG promoted the induction of mitogen-activated protein kinases (MAPKs) signaling pathways in only SNU-16 cells, but not in the SNU-1 cells. CLG exhibited apoptotic effects that caused an increased accumulation of the cells in sub-G1 phase and caspase-3 activation in both SNU-1 and SNU-16 cell lines. We also noticed that CLG and docetaxel co-treatment could exhibit significantly enhanced apoptotic effects against SNU-1 cells. Moreover, the combinations treatment of CLG and docetaxel markedly inhibited cell growth, phosphorylation of JAK-Src-STAT3 and induced substantial apoptosis. Additionally, pharmacological inhibition of JNK, p38, and ERK substantially blocked CLG-induced activation of MAPKs, cell viability, and apoptosis, thereby implicating the pivotal role of MAPKs in the observed anti-cancer effects of CLG. Taken together, our data suggest that CLG could effectively block constitutive STAT3/5 activation in SNU-1 cells but induce sustained MAPKs activation in SNU-16 cells.

Noninvasive transdermal delivery of liposomes by weak electric current

Noninvasive transdermal drug delivery (NTDD) offers an exciting new method of administration relative to conventional routes, but is associated with some challenges. Liposomes are capable of encapsulating transdermally-unfavorable drugs. However, the horny layer of skin is a significant barrier that limits efficient transdermal delivery of liposomes. Iontophoresis using weak electric current (WEC) represents a NTDD technology. WEC treatment of liposomes applied to the skin surface improves transdermal penetration of encapsulated drugs by cooperative effects. In this review, we provide an overview of the application of WEC/liposomes for transdermal delivery of macromolecules and low molecular weight drugs. We compare the transdermal delivery and therapeutic efficiency of the combined system with conventional routes of administration and their individual use. We discuss a novel perspective on the mechanism of WEC-mediated transdermal delivery of liposomes, which suggests that WEC activates the intracellular signaling pathway for transdermal permeation and induces unique endocytosis in skin cells.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.

Expression of DEC2 enhances chemosensitivity by inhibiting STAT5A in gastric cancer

Gastric cancer (GC) is one of the most common cancers. Resistance to 5-fluorouracil (5-Fu)-based chemotherapy is a major cause of treatment failure followed by the poor prognosis of patients. In GC, it was reported that human differentiated embryonic chondrocyte-expressed gene 2 (DEC2), suppressed tumor proliferation and metastasis, but the effect of DEC2 on chemosensitivity of GC cells was unknown. In our study, we found that DEC2 can obviously increase the sensibility of GC cells to 5-Fu by promoting 5-Fu-induced apoptosis. DEC2 overexpression is significantly associated with decreased phosphorylation of STAT5A (P-STAT5A). More importantly, negative correlations between DEC2 with P-STAT5A expression were observed in tissue sections from GC patients. GC patients with low expression levels of DEC2 and high expression levels of P-STAT5A showed a poor prognosis. Furthermore, enhanced chemosensitivity mediated by DEC2 can be reversed by STAT5A which confer GC cells resistance to apoptosis induced by 5-Fu. Together, our results suggest that through inhibiting activation of STAT5A, DEC2 enhances 5-Fu-induced apoptosis and suppression of proliferation in GC cells. These findings will provide new insight for identifying potential targets that can be used to sensitize GC cells to chemotherapy.

Silencing of COPB2 inhibits the proliferation of gastric cancer cells and induces apoptosis via suppression of the RTK signaling pathway

Emerging studies have reported that coatomer protein complex subunit β2 (COPB2) is overexpressed in several types of malignant tumor; however, to the best of our knowledge, no studies regarding COPB2 in gastric cancer have been published thus far. Therefore, the present study aimed to determine the significance and function of COPB2 in gastric cancer. COPB2 expression in gastric cancer cell lines was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. In addition, lentivirus-short hairpin RNA (shRNA) COPB2 (Lv-shCOPB2) was generated and used to infect BGC-823 cells to analyze the effects of COPB2 on the cancerous phenotype. The effects of shRNA-mediated COPB2 knockdown on cell proliferation were detected using MTT, 5-bromo-2-deoxyuridine and colony formation assays. In addition, the effects of COPB2 knockdown on apoptosis were analyzed by flow cytometry. Nude mice and fluorescence imaging were used to characterize the regulation of tumor growth in vivo, and qPCR and immunohistochemistry were subsequently conducted to analyze COPB2 expression in xenograft tumor tissues. Furthermore, a receptor tyrosine kinase (RTK) signaling pathway antibody array was used to explore the relevant molecular mechanisms underlying the effects of COPB2 knockdown. The results revealed that COPB2 mRNA was abundantly overexpressed in gastric cancer cell lines, whereas knockdown of COPB2 significantly inhibited cell growth and colony formation ability, and led to increased cell apoptosis in vitro. The tumorigenicity assay revealed that knockdown of COPB2 reduced tumor growth in nude mice, and fluorescence imaging indicated that the total radiant efficiency of mice in the Lv-shCOPB2-infected group was markedly reduced compared with the mice in the Lv-shRNA control-infected group in vivo. The antibody array assay revealed that the levels of phosphorylation in 23 target RTKs were significantly reduced: In conclusion, COPB2 was highly expressed in gastric cancer cell lines, and knockdown suppressed colony formation and promoted cell apoptosis via inhibiting the RTK signaling and its downstream signaling cascade molecules. Therefore, COPB2 may present a valuable target for gene silencing strategy in gastric cancer.

GRAM domain-containing protein 1B (GRAMD1B), a novel component of the JAK/STAT signaling pathway, functions in gastric carcinogenesis

Dysregulated JAK/STAT signaling has been implicated in the molecular pathogenesis of gastric cancer. However, downstream effectors of STAT signaling that facilitate gastric carcinogenesis remain to be explored. We previously identified the Drosophila ortholog of human GRAMD1B in our genome-wide RNAi screen to identify novel components of the JAK/STAT signaling pathway in Drosophila. Here, we examined the involvement of GRAMD1B in JAK/STAT-associated gastric carcinogenesis. We found that GRAMD1B expression is positively regulated by JAK/STAT signaling and GRAMD1B inhibition decreases STAT3 levels, suggesting the existence of a positive feedback loop. Consistently, GRAMD1B and JAK/STAT signaling acted synergistically to promote gastric cancer cell survival by upregulating the expression of the anti-apoptotic molecule Bcl-xL. Interestingly, our immunohistochemical analysis for GRAMD1B revealed a gradual loss of cytoplasmic staining but an increase in the nuclear accumulation of GRAMD1B, as gastric tissue becomes malignant. GRAMD1B expression levels were also found to be significantly associated with clinicopathological features of the gastric cancer patients, particularly the tumor grades and lymph node status. Moreover, GRAMD1B and pSTAT3 (Tyr705) showed a positive correlation in gastric tissues, thereby confirming the existence of a close link between these two signaling molecules in vivo. This new knowledge about JAK/STAT-GRAMD1B regulation deepens our understanding of JAK/STAT signaling in gastric carcinogenesis and provides a foundation for the development of novel biomarkers in gastric cancer.

Tyr23 phosphorylation of Anxa2 enhances STAT3 activation and promotes proliferation and invasion of breast cancer cells

PURPOSE

Overexpression of Annexin A2 (Anxa2) is positively correlated with breast cancer progression, drug resistance, and poor prognosis of patients with breast cancer. Tyr23 Phosphorylation by Src-family tyrosine kinase is an important post-translational modification of Anxa2. This modification regulates the subcellular localization and functions of Anxa2 and has significant effects on cell proliferation, migration, and invasion. This study aims at revealing the association of Anxa2-Tyr23 phosphorylation in Anxa2-mediated acceleration of breast cancer progression and their elaborate molecular mechanisms.

METHODS

Cell biological function experiments were performed to determine the effects of Anxa2-Tyr23 Phosphorylation on breast cancer cell proliferation and invasion in vitro and metastasis in vivo. The interaction of Tyr23 phosphorylated Anxa2 and STAT3 was verified by co-immunoprecipitation assay. Related mRNA and protein expression levels of cyclin D1 and MMP2/9 and phosphorylation level of STAT3 were detected.

RESULTS

Anxa2-Tyr23 phosphorylation is necessary for proliferation, invasion, and metastasis of breast cancer cells in vitro and in vivo. Tyr23 phosphorylated Anxa2 binds and enhances the sensitivity of STAT3 activation in response to IL-6, thereby increasing the protein and mRNA expression levels of cyclin D1 and MMP2/9 which are STAT3 key target genes and serve pivotal regulatory functions in cell proliferation and invasion, respectively.

CONCLUSION

Our findings further confirmed the regulatory role of Anxa2 and revealed the direct relationship between Anxa2-Tyr23 phosphorylation and activation of STAT3. Moreover, this study provides novel insights into the function of Anxa2-Tyr23 phosphorylation in signal transduction for further understanding of the mechanism through which Anxa2 promotes the progression of breast cancer.

Effects and mechanisms of action of SARI on androgen-independent prostate cancer (DU145) cells

This study aimed to characterize the role and mechanisms of action of suppressor of AP-1, regulated by IFN (SARI) in androgen-independent prostate cancer cells using the DU145 cell line. Prostate cancer cell lines were transfected to permit both the overexpression and inhibition of SARI. MTT assays and Transwell assays were performed to detect the effects of SARI overexpression and inhibition on the proliferation activity, invasiveness, and metastatic ability of DU145 cells. Expression of vascular endothelial growth factor (VEGF) and tyrosine-phosphorylated signal transducer and activator of transcription 3 (p-STAT3) was monitored in the experimental groups using a qPCR assay and western blot analysis. Additionally, DU145 cells were separately treated with 5, 50, and 100 μmol/L AG490 for 48 h and SARI expression was detected using the qPCR assay and western blot analysis. We also monitored the effects of AG490 treatment (100 μmol/L for 48 h) on both the SARI-SiRNA DU145 cells and empty vector DU145 (DU145-V) cells using the MTT assay and a Transwell migration assay. SARI overexpression and SARI-SiRNA DU145 prostate cancer cell lines were successfully established. The proliferation activity and the invasion and migration abilities of DU145-SARI cells were significantly lower compared with the DU145-V group (P < 0.05). Conversely, the proliferation activity and the invasion and migration abilities of SARI-SiRNA cells were significantly higher compared with the DU145-V group (P < 0.05). VEGF and p-STAT3 expression levels were lower in the SARI overexpression group compared with the DU145-V group and the control group (P < 0.05). In contrast, VEGF and p-STAT3 expression levels were higher in the SARI-SiRNA group compared with both the DU145-V group and the control group (P < 0.05). In comparison with the control group, SARI expression levels were higher in DU145 cells treated with 50 and 100 μmol/L AG490. Upon treatment with 100 μmol/L AG490 for 48 h, the proliferation activity and invasiveness and migration abilities of SARI-SiRNA cells were significantly higher compared with the DU145-V group (P < 0.05). SARI significantly affects the proliferation, invasion, and metastasis of DU145 cells. It is possible that SARI inhibits the proliferation, invasion, and migration of androgen-independent prostate cancer cells by regulating downstream genes through the SARI/STAT3/VEGF pathways.