Multiplex fluorescent immunohistochemistry quantitatively analyses microvascular density (MVD) and the roles of TGF-β signalling in orchestrating angiogenesis in colorectal cancer

Low-grade mammary gland tumours in dogs have greater VEGF-A and BMP2 immunostaining and higher CD31 blood vessel density

Tumor angiogenesis is an important process in tumor growth, and different molecules are involved in its regulation including VEGF-A, BMP2, and CD31, which can be considered possible prognostic markers. The aim of this study was to verify whether the VEGF-A and BMP2 immunostaining area, and microvascular density (MVD) might be associated with the degree of malignancy in malignant mammary neoplasms of dogs. For this purpose, samples of mammary malignancies from female dogs embedded in wax were used and separated into four main histomorphological types: tubulopapillary carcinomas, solid, complex, and carcinosarcoma, which were separated based on high and low degrees of malignancy. Immunohistochemical analysis was performed on tissue microarray blocks using anti-CD31 antibodies for evaluation of MVD and vascular lumen area, and with anti-VEGF-A and anti-BMP2 to determine the immunostaining area using the DAKO EnVision™ FLEX+ kit. MVD and vascular lumen area were higher in tubulopapillary carcinomas as were the areas stained by VEGF-A and BMP2. Immunostaining for CD31 was higher in low-grade carcinomas as well as in areas immunostained by VEGF-A and BMP2. There was a positive correlation between VEGF and BMP2 in high (r = 0.556, p < 0.0001) and low-grade (r = 0.287, p<0.0001) carcinomas and between MVD and VEGF-A in low-grade carcinomas (r = 0.267, p = 0.0064). Thus, the markers evaluated showed greater immunostaining in canine mammary tumors with a lower degree of malignancy.

TGF-β signaling pathway: Therapeutic targeting and potential for anti-cancer immunity

Transforming growth factor-β (TGFβ) is a pleiotropic secretory cytokine exhibiting both cancer-inhibitory and promoting properties. It transmits its signals via Suppressor of Mother against Decapentaplegic (SMAD) and non-SMAD pathways and regulates cell proliferation, differentiation, invasion, migration, and apoptosis. In non-cancer and early-stage cancer cells, TGFβ signaling suppresses cancer progression via inducing apoptosis, cell cycle arrest, or anti-proliferation, and promoting cell differentiation. On the other hand, TGFβ may also act as an oncogene in advanced stages of tumors, wherein it develops immune-suppressive tumor microenvironments and induces the proliferation of cancer cells, invasion, angiogenesis, tumorigenesis, and metastasis. Higher TGFβ expression leads to the instigation and development of cancer. Therefore, suppressing TGFβ signals may present a potential treatment option for inhibiting tumorigenesis and metastasis. Different inhibitory molecules, including ligand traps, anti-sense oligo-nucleotides, small molecule receptor-kinase inhibitors, small molecule inhibitors, and vaccines, have been developed and clinically trialed for blocking the TGFβ signaling pathway. These molecules are not pro-oncogenic response-specific but block all signaling effects induced by TGFβ. Nonetheless, targeting the activation of TGFβ signaling with maximized specificity and minimized toxicity can enhance the efficacy of therapeutic approaches against this signaling pathway. The molecules that are used to target TGFβ are non-cytotoxic to cancer cells but designed to curtail the over-activation of invasion and metastasis driving TGFβ signaling in stromal and cancer cells. Here, we discussed the critical role of TGFβ in tumorigenesis, and metastasis, as well as the outcome and the promising achievement of TGFβ inhibitory molecules in the treatment of cancer.

Overexpression of ELL-associated factor 2 suppresses invasion, migration, and angiogenesis in colorectal cancer

BACKGROUND

The androgen responsive gene, ELL-associated factor 2 (EAF2), expressed in benign prostate tissues, has been shown to play an important role in tumor suppression in a variety of malignant tumors. In addition, some scholars found that EAF2 frameshift mutations are associated with intratumor heterogeneity in colorectal cancer (CRC) and inactivation of EAF2 in microsatellite instability-high CRC. However, the molecular mechanism by which EAF2 is involved in CRC invasion and metastasis remains unclear.

AIM

To determine the clinical value of expression of EAF2 protein in CRC, and to study the effects of EAF2 on the invasion, migration, and angiogenesis of CRC cells in vitro.

METHODS

In this study, we collected colorectal adenocarcinoma and corresponding adjacent tissues to investigate the clinical expression of EAF2 protein in patients with advanced CRC. Subsequently, we investigated the effect of EAF2 on the invasion, migration, and angiogenesis of CRC cells in vitro using plasmid transfection.

RESULTS

EAF2 protein was lowly expressed in cancer tissues of patients with advanced CRC. Kaplan-Meier survival analysis showed that the survival rate of the high EAF2 level group was higher than that of the low EAF2 level group.

CONCLUSION

Our results demonstrated that EAF2, as a tumor suppressor, may inhibit the invasion, metastasis, and angiogenesis of CRC cells by regulating the signal transducer and activator of transcription 3/transforming growth factor-β1 crosstalk pathway, and play a cancer suppressive and protective role in the occurrence and development of CRC. Our findings are of great significance to provide a new idea and theoretical basis for the targeted diagnosis and treatment of CRC.

VPS9D1-AS1 overexpression amplifies intratumoral TGF-β signaling and promotes tumor cell escape from CD8+ T cell killing in colorectal cancer

Efficacy of immunotherapy is limited in patients with colorectal cancer (CRC) because high expression of tumor-derived transforming growth factor (TGF)-β pathway molecules and interferon (IFN)-stimulated genes (ISGs) promotes tumor immune evasion. Here, we identified a long noncoding RNA (lncRNA), VPS9D1-AS1, which was located in ribosomes and amplified TGF-β signaling and ISG expression. We show that high expression of VPS9D1-AS1 was negatively associated with T lymphocyte infiltration in two independent cohorts of CRC. VPS9D1-AS1 served as a scaffolding lncRNA by binding with ribosome protein S3 (RPS3) to increase the translation of TGF-β, TGFBR1, and SMAD1/5/9. VPS9D1-AS1 knockout downregulated OAS1, an ISG gene, which further reduced IFNAR1 levels in tumor cells. Conversely, tumor cells overexpressing VPS9D1-AS1 were resistant to CD8⁺ T cell killing and lowered IFNAR1 expression in CD8⁺ T cells. In a conditional overexpression mouse model, VPS9D1-AS1 enhanced tumorigenesis and suppressed the infiltration of CD8⁺ T cells. Treating tumor-bearing mice with antisense oligonucleotide drugs targeting VPS9D1-AS1 significantly suppressed tumor growth. Our findings indicate that the tumor-derived VPS9D1-AS1/TGF-β/ISG signaling cascade promotes tumor growth and enhances immune evasion and may thus serve as a potential therapeutic target for CRC.

Overexpression of NNT-AS1 Activates TGF-β Signaling to Decrease Tumor CD4 Lymphocyte Infiltration in Hepatocellular Carcinoma

Nicotinamide nucleotide transhydrogenase-antisense RNA1 (NNT-AS1) is a long noncoding RNA (lncRNA) that has been shown to be overexpressed in hepatocellular carcinoma (HCC). However, the molecular mechanism involving NNT-AS1 in HCC remains to be extensively investigated. The activation of TGF-β signaling inhibits tumor-infiltrating lymphocytes (TILs) and results in tumor immune evasion. We thus planned to explore the mechanism by which NNT-AS1 activates the TGF-β signaling pathway and inhibits TILs in HCC. High levels of NNT-AS1 were detected in HCC tissues by both RNAscope and real-time quantitative PCR (RT-qPCR) assays. The levels of proteins involved in TGF-β signaling and those of CD4 T lymphocytes were quantified by immunohistochemistry (IHC). HCC cell lines (HepG2 and Huh7) were used to explore the effects of NNT-AS1 on TGF-β signaling activation. In these analyses, RNAscope detection demonstrated that NNT-AS1 levels were significantly increased in HCC cancer tissues (P = 0.0001). In addition, the elevated NNT-AS1 levels in cancer tissue were further confirmed by RT-qPCR analysis of HCC cancer tissues (n = 64) and normal tissues (n = 26) (P = 0.0003). Importantly, the overall survival time of HCC patients who exhibited higher levels of NNT-AS1 expression was significantly shorter than that of HCC patients who had lower levels of NNT-AS1 expression (P = 0.0402). Further mechanistic investigation indicated that NNT-AS1 inhibition significantly decreased the levels of TGF-β, TGFBR1, and SMAD5 in HCC cells. In HCC tissues, IHC detection showed that relatively high NNT-AS1 levels were associated with a reduction in infiltrated CD4 lymphocyte numbers. In conclusion, this research identifies a novel mechanism by which NNT-AS1 impairs CD4 T cell infiltration via activation of the TGF-β signaling pathway in HCC.