Cancer Biology & Therapy最新文献

Background: Extracellular vesicle (EV) signaling is important in multiple malignancies, including pancreatic ductal adenocarcinoma (PDAC). In this coordinated cell‒cell signaling mechanism, genetically altered tumor cells signal to surrounding normal cells to promote tumor progression. Many efforts have been made to mechanistically interrogate this signaling axis by inhibiting EV secretion from cells. These techniques leverage our understanding of how EV biogenesis interferes with ceramide production or GTPase activity, which aids in membrane fusion with the plasma membrane.

Material and methods: Our group leveraged these methods in our orthotopic PDAC mouse model to investigate the importance of PDAC EV secretion. We interfered with the GTPases Rab27a and Rab35 and utilized an inhibitor of ceramide production (GW4869) to ablate EV secretion.

Results and conclusion: Overall, we found that these models did not perform as anticipated, and we could not consistently inhibit KPC cell EV secretion. These results emphasize the challenges of interfering with EV secretion, as several parallel pathways, such as direct membrane budding, can compensate. Further studies are needed to develop models for studying the role of EVs in vivo.

The cancer-immunity cycle is regulated by a series of stimulatory and inhibitory factors. The stimulator of interferon genes (STING) pathway, a key stimulator of type I interferon production, connects innate and adaptive immunity to promote antitumor responses. Using a syngeneic pancreatic tumor model, we characterized the single-cell landscape changes induced by STING stimulation. Our findings revealed that STING agonist treatment reprograms transcription across multiple cell lineages, enhances innate immune responses and activates lymphocytes, thereby promoting antitumor effects. Single-cell transcriptome sequencing identified significant increases in monocytes, neutrophils, macrophages, and CD8 T cells, indicating augmented tumor inflammation. Differential gene expression analysis highlighted upregulated genes related to immune cell effector mechanisms and antigen presentation. Functional assays confirmed the enhanced tumor killing effects induced by STING activation. These results underscore the potential of STING agonists in reprogramming the tumor microenvironment to potentiate antitumor immunity, although clinical translation remains challenging owing to pharmacokinetic limitations and potential systemic toxicity. Further research is needed to optimize STING agonist delivery and dosage for effective cancer immunotherapy.

Background: The tumour microenvironment (TME) significantly influences intercellular communication, with several secreted factors activating both tumour cells and fibroblasts. Connexin43 (Cx43), a crucial gap junction protein, exhibits a significant regulatory role in tumourigenesis; however, the underlying regulatory mechanisms in colorectal cancer (CRC) are not fully understood.

Methods: Transwell co-culture system was utilized to evaluate fibroblast-mediated effects on CRC cells. Immunohistochemical analysis was conducted on clinical specimens. Cell migration and invasion capabilities were measured using Transwell assays. Subcellular localization was assessed via immunofluorescence. Protein interactions were validated by co-immunoprecipitation.

Results: The Wnt signalling pathway was activated in the co-culture of CRC cells and fibroblasts. Nuclear Cx43 upregulation was detected and confirmed as a pro-oncogenic factor via prognostic analysis of patient samples. Therefore, although Cx43 on the cell membrane serves as a tumour suppressor, the nuclear translocation of Cx43 has an important influence on the Wnt signalling pathway and promotes CRC progression. Nuclear translocation of Cx43 during malignant progression has a significant effect on metastasis and is regulated by secreted TGF-β. Distinct nuclear translocation patterns of Cx43 observed across CRC cell lines suggest potential regulation by S368 phosphorylation. Co-immunoprecipitation confirmed Cx43/β-catenin interaction, revealing its role in facilitating β-catenin nuclear accumulation.

Conclusion: We systematically identified nuclear Cx43 as a factor promoting CRC progression. These findings highlight the novel mechanism involving the nuclear translocation of Cx43 as a promoting factor in CRC progression, and enhance our understanding of the interplay between the TME and CRC progression.

Adaptive immune resistance in cancer describes the various mechanisms by which tumors adapt to evade anti-tumor immune responses. IFN-γ induction of programmed death-ligand 1 (PD-L1) was the first defined and validated adaptive immune resistance mechanism. The endoplasmic reticulum (ER) is central to adaptive immune resistance as immune modulatory secreted and integral membrane proteins are dependent on ER. Sigma1 is a unique ligand-regulated integral membrane scaffolding protein enriched in the ER of cancer cells. PD-L1 is an integral membrane glycoprotein that is translated into the ER and processed through the cellular secretory pathway. At the cell surface, PD-L1 is an immune checkpoint molecule that binds PD-1 on activated T-cells and blocks anti-tumor immunity. PD-L1 can also be incorporated into cancer cell-derived extracellular vesicles (EVs), and EV-associated PD-L1 can inactivate T-cells within the tumor microenvironment. Here, we demonstrate that a selective small molecule inhibitor of Sigma1 can block IFN-γ mediated adaptive immune resistance in part by altering the incorporation of PD-L1 into cancer cell-derived EVs. Sigma1 inhibition blocked post-translational maturation of PD-L1 downstream of IFN-γ/STAT1 signaling. Subsequently, EVs released in response to IFN-γ stimulation were significantly less potent suppressors of T-cell activation. These results suggest that by reducing tumor derived immune suppressive EVs, Sigma1 inhibition may promote antitumor immunity. Sigma1 modulation presents a novel approach to regulating the tumor immune microenvironment by altering the content and production of EVs. Altogether, these data support the notion that Sigma1 may play a role in adaptive immune resistance in the tumor microenvironment.

Background: Peptide vaccines offer a direct way to initiate an immunogenic response to a defined antigen epitope. However, peptide vaccines are unstable in vivo, subject to rapid enzymatic proteolysis. Replacement of an α-amino acid residue with a homologous β-amino acid residue (native side chain, but backbone extended by a single CH₂ unit) impairs proteolysis at nearby amide bonds. Therefore, antigen analogues containing α-to-β replacements have been examined for functional mimicry of native all-α antigens. Another group previously took this approach in the ovalbumin (OVA) antigen model by evaluating single α-to-β analogues of the murine major histocompatibility complex (MHC) I-restricted peptide SIINFEKL.

Methods: We re-examined this set of α/β SIINFEKL antigens. We tested the susceptibility to proteolysis in mouse serum and their ability to activate OVA-antigen-specific CD8 T cells in vitro. Additionally, we tested the α/β antigens in vivo for their ability to induce an antigen-specific immunogenic response in naïve mice and in OVA-expressing tumor-bearing mice.

Results: The α/β antigens were comparable to the native antigen in their susceptibility to proteolysis in serum. Each α/β antigen was capable of activating antigen-specific CD8 T cells in vitro. However, antigen-specific CD8 T cells induced against α/β antigens in vivo were not cross-reactive to the native antigen. Moreover, immunization with α/β analogues did not elicit anti-tumor effects in tumor-bearing mice.

Conclusions: We conclude that even though α/β analogues of the SIINFEKL antigen can elicit a T cell-based response, this class of backbone-modified peptides is not promising from the perspective of antitumor vaccine development.

Lung cancer, one of the most prevalent tumors, remains a clinical challenge with a poor five-year survival rate. Daurisoline, a bis-benzylisoquinoline alkaloid derived from the traditional Chinese herb Menispermum dauricum, is known to suppress tumor growth effectively. However, its precise mechanism of action remains unclear. In this study, we demonstrate that Daurisoline targets glycolysis and reduces the protein level of HK2, thereby inhibiting lung cancer progression. Mechanistic investigations reveal that Daurisoline directly binds to AKT and antagonizes the AKT-GSK3β-c-Myc-HK2 signaling axis. Furthermore, in an animal model, we validate the in vivo anti-tumor effect of Daurisoline without any observable side effects. Overall, our findings suggest that Daurisoline holds potential as an anti-tumor agent through its targeting of glycolysis.

Purpose: Neoadjuvant chemotherapy (NAC) has proven valuable in treating locally advanced colon cancer (LACC) and is included as a treatment option for patients with clinical T4b colon cancer by the National Comprehensive Cancer Network. However, the long-term survival benefit of NAC in LACC remains debated, due to a lack of conclusive clinical trial results identifying the patients who would benefit most from NAC. This study aimed to assess the efficacy of NAC in patients with LACC based on histological subtype.

Patients and methods: This retrospective study analyzed 3,709 patients with LACC who underwent curative resection at Harbin Medical University Cancer Hospital between 2014 and 2018. Patients were grouped into two groups: neoadjuvant chemotherapy (NAC) and adjuvant chemotherapy (AC) groups. Propensity score matching (PSM) was used to adjust for confounders, and survival outcomes of the two groups across different histological subtypes were evaluated using Kaplan-Meier (K-M) curves and log-rank tests.

Results: Patients with non-mucinous adenocarcinoma (NMAC) treated with NAC had a significantly improved 5-year OS rate (76.3% vs. 69.2%, p = .039) and DFS rate (67.2% vs. 60.1%, p = .041) compared with patients treated with AC. However, there was no significant difference in OS and DFS between the two treatment groups among patients with mucinous adenocarcinoma (MAC) and signet ring cell carcinoma (SRCC).

Conclusion: In patients with LACC, the prognostic value of NAC varied by histology. NMAC may serve as a predictor of improved long-term survival benefit from NAC in these patients.

Endostar is a human recombinant endostatin which is an attractive anti-angiogenesis protein. Because inefficient antigen presenting MHC class I expression (which can be downregulated by HIF-1) is an important strategy for cancer immune evasion, besides its anti-angiogenesis effect, it remains unclear whether Endostar has an inhibitory effect on HIF-1 expression by upregulating MHC class I expression in cancer cells to facilitate immunotherapies, including PD-1/PD-L1 inhibitors. In this study, A549 and NCI-H1299 lung cancer cells were treated with Endostar (6.25 μg/ml, 12.5 μg/ml, and 25 μg/ml, respectively). HIF-1 expression was detected by Immunocytochemistry and Western blot. Proteins of the MHC class I α-heavy chain and β2 m light chain, STAT3 and pSTAT3 were detected by Western blot. The mRNAs of MHC class I α-heavy chain and β2 m light chain were detected by RT-qPCR. It was shown that decreased expression of HIF-1 and promotion of β2-microglobulin were observed after Endostar treatment. In addition, elevated levels of MHC class I α-heavy chain mRNA and protein, as well as downregulation of STAT3 and pSTAT3, were also observed following Endostar treatment. Endostar inhibited HIF-1 expression in A549 and NCI-H1299 lung cancer cells, upregulated expression of MHC class I α-heavy chain and β2 m light chain, with the upregulation of STAT3 and pSTAT3, suggesting involvement of STAT3 pathway. It is important because only in combination with MHC class I on target cells can tumor antigenic peptides be recognized by CD8+ CTLs which destroy target cells. However, MHC class I is frequently deficient in cancer cells.