Analysis of differential gene expression by bead-based fiber-optic array in growth-hormone-secreting pituitary adenomas

HIGD1B, as a novel prognostic biomarker, is involved in regulating the tumor microenvironment and immune cell infiltration; its overexpression leads to poor prognosis in gastric cancer patients

Background

HIGD1B (HIG1 Hypoxia Inducible Domain Family Member 1B) is a protein-coding gene linked to the occurrence and progression of various illnesses. However, its precise function in gastric cancer (GC) remains unclear.

Methods

The expression of HIGD1B is determined through the TCGA and GEO databases and verified using experiments. The association between HIGD1B and GC patients' prognosis was analyzed via the Kaplan-Meier (K-M) curve. Subsequently, the researchers utilized ROC curves to assess the diagnostic capacity of HIGD1B and employed COX analysis to investigate risk factors for GC. The differentially expressed genes (DEGs) were then subjected to functional enrichment analysis, and a nomogram was generated to forecast the survival outcome and probability of GC patients. Additionally, we evaluated the interaction between HIGD1B and the immune cell infiltration and predicted the susceptibility of GC patients to therapy.

Results

HIGD1B is markedly elevated in GC tissue and cell lines, and patients with high HIGD1B expression have a poorer outcome. In addition, HIGD1B is related to distinct grades, stages, and T stages. The survival ROC curves of HIGD1B and nomogram for five years were 0.741 and 0.735, suggesting appropriate levels of diagnostic efficacy. According to Cox regression analysis, HIGD1B represents a separate risk factor for the prognosis of gastric cancer (p<0.01). GSEA analysis demonstrated that the HIGD1B is closely related to cancer formation and advanced pathways. Moreover, patients with high HIGD1B expression exhibited a higher level of Tumor-infiltration immune cells (TIICs) and were more likely to experience immune escape and drug resistance after chemotherapy and immunotherapy.

Conclusion

This study explored the potential mechanisms and diagnostic and prognostic utility of HIGD1B in GC, as well as identified HIGD1B as a valuable biomarker and possible therapeutic target for GC.

High expression of homeobox B2 predicts poor survival of colon adenocarcinoma by enhancing tumor proliferation and invasion

OBJECTIVE

Homeobox B2 (HOXB2) is known to be correlated with the development and prognosis of various cancers. However, its role in colon cancer remains unclear.

AIMS

In this study, we explored the prognostic value of HOXB2 in colon adenocarcinoma (COAD).

METHODS

A total of 264 colon adenocarcinoma cases were retrospectively enrolled to evaluate HOXB2 expression and clinical significance. Chi-square test was applied to identify relationship between clinical features and HOXB2 expression. The effect of HOXB2 expression and clinical features on the survival of COAD patients was evaluated using Kaplan-Meier and Cox regression analyses. Cellular assays and mice models were conducted to validate the tumor-related role of HOXB2 in COAD.

RESULTS

Higher expression of HOXB2 in COAD tissues was significantly associated with tumor size, invasion depth, and lymph node metastasis (all P < 0.05). Univariate and multivariate analyses showed that high expression of HOXB2 was significantly correlated with a poor overall survival. In vitro cellular assays combined with knockdown strategies demonstrated that HOXB2 can promote tumor proliferation and invasion of COAD, which was further confirmed by in vivo xenograft experiments.

CONCLUSIONS

HOXB2 may be a valuable biomarker and potential therapeutic target for the treatment of COAD.

Tumor microenvironment defines the invasive phenotype of AIP-mutation-positive pituitary tumors

The molecular mechanisms leading to aryl hydrocarbon receptor interacting protein (AIP) mutation-induced aggressive, young-onset growth hormone-secreting pituitary tumors are not fully understood. In this study, we have identified that AIP-mutation-positive tumors are infiltrated by a large number of macrophages compared to sporadic tumors. Tissue from pituitary-specific Aip-knockout (Aip^Flox/Flox;Hesx1^Cre/+) mice recapitulated this phenotype. Our human pituitary tumor transcriptome data revealed the "epithelial-to-mesenchymal transition (EMT) pathway" as one of the most significantly altered pathways in AIPpos tumors. Our in vitro data suggest that bone marrow-derived macrophage-conditioned media induces more prominent EMT-like phenotype and enhanced migratory and invasive properties in Aip-knockdown somatomammotroph cells compared to non-targeting controls. We identified that tumor-derived cytokine CCL5 is upregulated in AIP-mutation-positive human adenomas. Aip-knockdown GH3 cell-conditioned media increases macrophage migration, which is inhibited by the CCL5/CCR5 antagonist maraviroc. Our results suggest that a crosstalk between the tumor and its microenvironment plays a key role in the invasive nature of AIP-mutation-positive tumors and the CCL5/CCR5 pathway is a novel potential therapeutic target.

Inhibition of Notch signaling attenuates pituitary adenoma growth in Nude mice

Preclinical and clinical studies support that Notch signaling may play an important oncogenic role in cancer, but there is scarce information for pituitary tumors. We therefore undertook a functional study to evaluate Notch participation in pituitary adenoma growth. Tumors generated in Nude mice by subcutaneous GH3 somatolactotrope cell injection were treated in vivo with DAPT, a γ-secretase inhibitor, thus inactivating Notch signaling. This treatment led to pituitary tumor reduction, lower prolactin and GH tumor content and a decrease in angiogenesis. Furthermore, in silico transcriptomic and epigenomic analyses uncovered several tumor suppressor genes related to Notch signaling in pituitary tissue, namely Btg2, Nr4a1, Men1, Zfp36 and Cnot1. Gene evaluation suggested that Btg2, Nr4a1 and Cnot1 may be possible players in GH3 xenograft growth. Btg2 mRNA expression was lower in GH3 tumors compared to the parental line, and DAPT increased its expression levels in the tumor in parallel with the inhibition of its volume. Cnot1 mRNA levels were also increased in the pituitary xenografts by DAPT treatment. And the Nr4a1 gene was lower in tumors compared to the parental line, though not modified by DAPT. Finally, because DAPT in vivo may also be acting on tumor microenvironment, we determined the direct effect of DAPT on GH3 cells in vitro. We found that DAPT decreases the proliferative, secretory and migration potential of GH3 cells. These results position selective interruption of Notch signaling as a potential therapeutic tool in adjuvant treatments for aggressive or resistant pituitary tumors.

Loss of 15-hydroxyprostaglandin dehydrogenase indicates a tumor suppressor role in pituitary adenomas

15-hydroxyprostaglandin dehydrogenase (15-PGDH) may function as a tumor suppressor that antagonizes the action of the cyclooxygenase-2 (COX-2) oncogene in several types of tumors. However, it is unknown if it has a role in the pituitary. Recently, our group found that 15-PGDH expression was low in prolactin (PRL) secreting adenomas (prolactinomas) and growth hormone (GH) secreting adenomas (GHomas) using fiber-optic BeadArray technology. In this study, we examined the relative expression of 15-PGDH and COX-2 mRNA in clinical specimens and examined the effects of 15-PGDH on GH3 rat pituitary tumor cell proliferation, apoptosis and hormone secretion. 15-PGDH expression was lower and COX-2 expression was higher in prolactinomas and GHomas compared with normal controls. Overexpressed 15-PGDH inhibited tumor cell proliferation and induced apoptosis. It had a significant suppressive effect on mRNA levels and on the secretion of PRL and GH in GH3 cells. The inhibition of cell proliferation was accompanied by the decreased expression of cox-2, matrix metalloproteinase-9 (MMP-9) and B cell leukemia/lymphoma-2 (Bcl-2). These data are suggestive of a previously unrecognized pathway in pituitary tumorigenesis, and this novel observation may shed light on therapeutic strategies for pituitary tumors.

Effects of fulvestrant on biological activity and Wnt expression in rat GH3 cells

The present study investigated the influence of anti-estrogen treatment (fulvestrant) on pituitary adenoma cell line GH3 biological activity, the estrogen receptor α pathway, the WnT pathway, and mechanisms of decreased Wnt inhibitory factor-1 expression in GH3 cells. Results showed that fulvestrant suppressed GH3 cell proliferation and reduced hormone secretion in a dose-dependent manner. Estrogen receptor α and Wnt4 expression decreased, but Wnt inhibitory factor-1 expression increased in a dose-dependent manner following fulvestrant treatment, and β-catenin expression remained unchanged. Inhibitors of DNA methylation and histone modification upregulated Wnt inhibitory factor-1 expression. Results suggested that fulvestrant suppressed biological activity of GH3 cells via the estrogen receptor α and Wnt pathways. These results suggested that decreased Wnt inhibitory factor-1 expression in GH3 cells played a role in epigenetic mechanisms. Anti-estrogen therapies could provide novel treatments for growth hormone adenomas.