Cancer/testis antigens: promising immunotherapy targets for digestive tract cancers

Digestive tract cancers, including esophageal, gastric, and colorectal cancers, are the major cause of death among cancer patients worldwide due to the heterogeneity of cancer cells, which limits the effectiveness of traditional treatment methods. Immunotherapy represents a promising treatment strategy for improving the prognosis of patients with digestive tract cancers. However, the clinical application of this approach is limited by the absence of optimal targets. Cancer/testis antigens are characterized by low or absent expression in normal tissues, but high expression in tumor tissues, making them an attractive target for antitumor immunotherapy. Recent preclinical trials have shown promising results for cancer/testis antigen-targeted immunotherapy in digestive cancer. However, practical problems and difficulties in clinical application remain. This review presents a comprehensive analysis of cancer/testis antigens in digestive tract cancers, covering their expression, function, and potential as an immunotherapy target. Additionally, the current state of cancer/testis antigens in digestive tract cancer immunotherapy is discussed, and we predict that these antigens hold great promise as an avenue for breakthroughs in the treatment of digestive tract cancers

Structural Diversity of the Active N-Terminal Kinase Domain of p90 Ribosomal S6 Kinase 2

The p90 ribosomal protein kinase 2 (RSK2) is a highly expressed Ser/Thr kinase activated by growth factors and is involved in cancer cell proliferation and tumor promoter-induced cell transformation. RSK2 possesses two non-identical kinase domains, and the structure of its N-terminal domain (NTD), which is responsible for phosphorylation of a variety of substrates, is unknown. The crystal structure of the NTD RSK2 was determined at 1.8 Å resolution in complex with AMP-PNP. The N-terminal kinase domain adopted a unique active conformation showing a significant structural diversity of the kinase domain compared to other kinases. The NTD RSK2 possesses a three-stranded βB-sheet inserted in the N-terminal lobe, resulting in displacement of the αC-helix and disruption of the Lys-Glu interaction, classifying the kinase conformation as inactive. The purified protein was phosphorylated at Ser227 in the T-activation loop and exhibited in vitro kinase activity. A key characteristic is the appearance of a new contact between Lys216 (βB-sheet) and the β-phosphate of AMP-PNP. Mutation of this lysine to alanine impaired both NTDs in vitro and full length RSK2 ex vivo activity, emphasizing the importance of this interaction. Even though the N-terminal lobe undergoes structural re-arrangement, it possesses an intact hydrophobic groove formed between the αC-helix, the β4-strand, and the βB-sheet junction, which is occupied by the N-terminal tail. The presence of a unique βB-sheet insert in the N-lobe suggests a different type of activation mechanism for RSK2

Targeting CRAF kinase in anti-cancer therapy: progress and opportunities

Abstract The RAS/mitogen-activated protein kinase (MAPK) signaling cascade is commonly dysregulated in human malignancies by processes driven by RAS or RAF oncogenes. Among the members of the RAF kinase family, CRAF plays an important role in the RAS-MAPK signaling pathway, as well as in the progression of cancer. Recent research has provided evidence implicating the role of CRAF in the physiological regulation and the resistance to BRAF inhibitors through MAPK-dependent and MAPK-independent mechanisms. Nevertheless, the effectiveness of solely targeting CRAF kinase activity remains controversial. Moreover, the kinase-independent function of CRAF may be essential for lung cancers with KRAS mutations. It is imperative to develop strategies to enhance efficacy and minimize toxicity in tumors driven by RAS or RAF oncogenes. The review investigates CRAF alterations observed in cancers and unravels the distinct roles of CRAF in cancers propelled by diverse oncogenes. This review also seeks to summarize CRAF-interacting proteins and delineate CRAF's regulation across various cancer hallmarks. Additionally, we discuss recent advances in pan-RAF inhibitors and their combination with other therapeutic approaches to improve treatment outcomes and minimize adverse effects in patients with RAF/RAS-mutant tumors. By providing a comprehensive understanding of the multifaceted role of CRAF in cancers and highlighting the latest developments in RAF inhibitor therapies, we endeavor to identify synergistic targets and elucidate resistance pathways, setting the stage for more robust and safer combination strategies for cancer treatment

PBK/TOPK: An Effective Drug Target with Diverse Therapeutic Potential

T-lymphokine-activated killer cell-originated protein kinase (TOPK, also known as PDZ-binding kinase or PBK) plays a crucial role in cell cycle regulation and mitotic progression. Abnormal overexpression or activation of TOPK has been observed in many cancers, including colorectal cancer, triple-negative breast cancer, and melanoma, and it is associated with increased development, dissemination, and poor clinical outcomes and prognosis in cancer. Moreover, TOPK phosphorylates p38, JNK, ERK, and AKT, which are involved in many cellular functions, and participates in the activation of multiple signaling pathways related to MAPK, PI3K/PTEN/AKT, and NOTCH1; thus, the direct or indirect interactions of TOPK make it a highly attractive yet elusive target for cancer therapy. Small molecule inhibitors targeting TOPK have shown great therapeutic potential in the treatment of cancer both in vitro and in vivo, even in combination with chemotherapy or radiotherapy. Therefore, targeting TOPK could be an important approach for cancer prevention and therapy. Thus, the purpose of the present review was to consider and analyze the role of TOPK as a drug target in cancer therapy and describe the recent findings related to its role in tumor development. Moreover, this review provides an overview of the current progress in the discovery and development of TOPK inhibitors, considering future clinical applications

Local Acoustic Fields Powered Assembly of Microparticles and Applications

Controllable assembly in nano-/microscale holds considerable promise for bioengineering, intracellular manipulation, diagnostic sensing, and biomedical applications. However, up to now, micro-/nanoscopic assembly methods are severely limited by the fabrication materials, as well as energy sources to achieve the effective propulsion. In particular, reproductive manipulation and customized structure is quite essential for assemblies to accomplish a variety of on-demand tasks at small scales. Here, we present an attractive assembly strategy to collect microparticles, based on local acoustic forces nearby microstructures. The micro-manipulation chip is built based on an enhanced acoustic field, which could tightly trap microparticles to the boundaries of the microstructure by tuning the applied driving frequency and voltage. Numerical simulations and experimental demonstrations illustrate that the capturing and assembly of microparticles is closely related to the size of particles, owing to the vibration-induced locally enhanced acoustic field and resultant propulsion force. This acoustic assembly strategy can open extensive opportunities for lab-on-chip systems, microfactories, and micro-manipulators, among others

(S)-10-Hydroxycamptothecin Inhibits Esophageal Squamous Cell Carcinoma Growth In Vitro and In Vivo Via Decreasing Topoisomerase I Enzyme Activity

Topoisomerase (TOP) I plays a major role in the process of supercoiled DNA relaxation, thereby facilitating DNA replication and cell cycle progression. The expression and enzymatic activity of TOP I is positively correlated with tumor progression. Although the anticancer activity of (S)-10-Hydroxycamptothecin (HCPT), a TOP I specific inhibitor, has been reported in various cancers, the effect of HCPT on esophageal cancer is yet to be examined. In this study, we investigate the potential of HCPT to inhibit the growth of ESCC cells in vitro and verify its anti-tumor activity in vivo by using a patient-derived xenograft (PDX) tumor model in mice. Our study revealed the overexpression of TOP I in ESCC cells and treatment with HCPT inhibited TOP I enzymatic activity at 24 h and decreased expression at 48 h and 72 h. HCPT also induced DNA damage by increasing the expression of H2A.XS139. HCPT significantly decreased the proliferation and anchorage-independent growth of ESCC cells (KYSE410, KYSE510, KYSE30, and KYSE450). Mechanistically, HCPT inhibited the G2/M phase cell cycle transition, decreased the expression of cyclin B1, and elevated p21 expression. In addition, HCPT stimulated ESCC cells apoptosis, which was associated with elevated expression of cleaved PARP, cleaved caspase-3, cleaved caspase-7, Bax, Bim, and inhibition of Bcl-2 expression. HCPT dramatically suppressed PDX tumor growth and decreased the expression of Ki-67 and TOP I and increased the level of cleaved caspase-3 and H2A.XS139 expression. Taken together, our data suggested that HCPT inhibited ESCC growth, arrested cell cycle progression, and induced apoptosis both in vitro and in vivo via decreasing the expression and activity of TOP I enzyme

DUSP4 promotes esophageal squamous cell carcinoma progression by dephosphorylating HSP90β

Summary: The molecular and pathogenic mechanisms of esophageal squamous cell carcinoma (ESCC) development are still unclear, which hinders the development of effective treatments. In this study, we report that DUSP4 is highly expressed in human ESCC and is negatively correlated with patient prognosis. Knockdown of DUSP4 suppresses cell proliferation and patient-derived xenograft (PDX)-derived organoid (PDXO) growth and inhibits cell-derived xenograft (CDX) development. Mechanistically, DUSP4 directly binds to heat shock protein isoform β (HSP90β) and promotes the ATPase activity of HSP90β by dephosphorylating HSP90β on T214 and Y216. These dephosphorylation sites are critical for the stability of JAK1/2-STAT3 signaling and p-STAT3 (Y705) nucleus translocation. In vivo, Dusp4 knockout in mice significantly inhibits 4-nitrochinoline-oxide-induced esophageal tumorigenesis. Moreover, DUSP4 lentivirus or treatment with HSP90β inhibitor (NVP-BEP800) significantly impedes PDX tumor growth and inactivates the JAK1/2-STAT3 signaling pathway. These data provide insight into the role of the DUSP4-HSP90β-JAK1/2-STAT3 axis in ESCC progression and describe a strategy for ESCC treatment

Improved Antitumor Efficacy of Combined Vaccine Based on the Induced HUVECs and DC-CT26 Against Colorectal Carcinoma

Angiogenesis is essential for the development, growth, and metastasis of solid tumors. Vaccination with viable human umbilical vein endothelial cells (HUVECs) has been used for antitumor angiogenesis. However, the limited immune response induced by HUVECs hinders their clinical application. In the present study, we found that HUVECs induced by a tumor microenvironment using the supernatant of murine CT26 colorectal cancer cells exerted a better antiangiogenic effect than HUVECs themselves. The inhibitory effect on tumor growth in the induced HUVEC group was significantly better than that of the HUVEC group, and the induced HUVEC group showed a strong inhibition in CD31-positive microvessel density in the tumor tissues. Moreover, the level of anti-induced HUVEC membrane protein antibody in mouse serum was profoundly higher in the induced HUVEC group than in the HUVEC group. Based on this, the antitumor effect of a vaccine with a combination of induced HUVECs and dendritic cell-loading CT26 antigen (DC-CT26) was evaluated. Notably, the microvessel density of tumor specimens was significantly lower in the combined vaccine group than in the control groups. Furthermore, the spleen index, the killing effect of cytotoxic T lymphocytes (CTLs), and the concentration of interferon-γ in the serum were enhanced in the combined vaccine group. Based on these results, the combined vaccine targeting both tumor angiogenesis and tumor cells may be an attractive and effective cancer immunotherapy strategy

Establishment of lung cancer patient-derived xenograft models and primary cell lines for lung cancer study

Abstract Background The overall 5-year survival rate of lung cancer is about 15% even with therapeutic drugs like tyrosine kinase inhibitors. Ideal models are urgently needed for exploring mechanisms and finding new drugs. Patient-derived xenografts (PDX) models and primary cells are both used to screen therapeutic regimens for cancer. However, PDX models and primary cells from the same patient are difficult to establish. Their consistency to the original tumor tissue is not well studied. Methods 31 lung cancer patient tissues were procured to establish the lung cancer PDX models and primary cell lines. Tumor growth measurements, histological and immunohistochemistry analysis, Western blotting, EGFR and K-RAS mutation detection and gefitinib sensitive assay were performed to evaluate the characteristic of established PDX models. Immunofluorescence analysis, anchorage-independent cell growth, Western blotting and gefitinib sensitive assay were performed to assay the characteristic of established primary cell lines. The whole-exome sequencing was used to compare the characteristic of the patient’s tumor tissue, established PDX and primary cell line. Results Twenty-one lung cancer PDX models (67.74%, 21/31) and ten primary cell lines (32.25%, 10/31) were established from patients’ tumor tissues. The histology and pathological immunohistochemistry of PDX xenografts are consistent with the patients’ tumor samples. Various signal pathways were activated in different PDX models (n = 5) and primary cell lines (n = 2). EGFR mutation PDX model and primary cell line (LG1) were sensitive to gefitinib treatment. The expression of CK8/18, TTF1 and NapsinA in LG1 and LG50 primary cells were also positive. And the activated signal pathways were activated in LG1 and LG50 primary cell lines. Furthermore, the gene mutation in PDX tumor tissues and primary cell line (LG50) was consistent with the mutation in LG50 patient’s tumor tissues. Conclusion These data suggested that established lung cancer PDX models and primary cell lines reserved mostly molecular characteristics of primary lung cancer and could provide a new tool to further understand the mechanisms and explore new therapeutic strategies