Altered Expression of High Molecular Weight Heat Shock Proteins after OCT4B1 Suppression in Human Tumor Cell Lines

Metformin-Induced Heat Shock Protein Family A Member 6 Is a Promising Biomarker of Esophageal Squamous Cell Carcinoma

INTRODUCTION

Anti-diabetic drug metformin exerts various anti-tumor effects on different cancers. Esophageal squamous cell carcinoma (ESCC) is an intractable digestive organ cancer and new treatment strategy is required. In this study, we performed a comprehensive gene expression analysis of esophageal squamous cell carcinoma (ESCC) cell lines treated with metformin, which provided helpful information on the anti-tumor effects of metformin in ESCC. Next, we selected a promising gene among them and examined its effects on ESCC properties.

METHODS

We examined metformin-induced mRNA expression changes in two human esophageal squamous cell carcinoma (ESCC) cell lines by performing next-generation sequencing (NGS) and pathway analysis. Heat shock protein family A (Hsp70) member 6 (HSPA6) expression in surgical specimens obtained from 83 ESCC patients who underwent curative operations was evaluated immunohistochemically and analyzed.

RESULTS

Metformin upregulated mRNA expression of the many genes, including HSPA6, a cancer immune related gene, and inhibited mRNA expression of the other many genes. Pathway analysis indicated major canonical pathways and upstream regulators related to metformin. The result indicated HSPA6 as a promising biomarker. HSPA6 expression correlated with disease-free survival (DFS) of the patients with all stage ESCC (p = 0.021), especially with stage I/II ESCC (p <0.001). With stage III, low HSPA6 expression was not associated with poor DFS (p = 0.918). Multivariate analysis indicated that independent low HSPA6 expression was an independent poor prognostic factor of stage I/II ESCC (p <0.001). However, HSPA6 expression did not correlate with the clinicopathological characteristics, including age, sex, tumor depth, lymph node metastasis, tumor stage, and tumor markers of the patients with stage I/II ESCC.

CONCLUSIONS

This NGS analysis detected prospective candidate genes, including HSPA6. Our results indicate that HSPA6 is a promising biomarker of the recurrence risk of stage I/II ESCC. Further studies on HSPA6 would lead to better treatment.

Study of the active ingredients and mechanism of Sparganii rhizoma in gastric cancer based on HPLC-Q-TOF-MS/MS and network pharmacology

Sparganii rhizoma (SL) has potential therapeutic effects on gastric cancer (GC), but its main active ingredients and possible anticancer mechanism are still unclear. In this study, we used HPLC-Q-TOF–MS/MS to comprehensively analyse the chemical components of the aqueous extract of SL. On this basis, a network pharmacology method incorporating target prediction, gene function annotation, and molecular docking was performed to analyse the identified compounds, thereby determining the main active ingredients and hub genes of SL in the treatment of GC. Finally, the mRNA and protein expression levels of the hub genes of GC patients were further analysed by the Oncomine, GEPIA, and HPA databases. A total of 41 compounds were identified from the aqueous extract of SL. Through network analysis, we identified seven main active ingredients and ten hub genes: acacetin, sanleng acid, ferulic acid, methyl 3,6-dihydroxy-2-[(2-hydroxyphenyl) ethynyl]benzoate, caffeic acid, adenine nucleoside, azelaic acid and PIK3R1, PIK3CA, SRC, MAPK1, AKT1, HSP90AA1, HRAS, STAT3, FYN, and RHOA. The results indicated that SL might play a role in GC treatment by controlling the PI3K-Akt and other signalling pathways to regulate biological processes such as proliferation, apoptosis, migration, and angiogenesis in tumour cells. In conclusion, this study used HPLC-Q-TOF–MS/MS combined with a network pharmacology approach to provide an essential reference for identifying the chemical components of SL and its mechanism of action in the treatment of GC.

Role of HSPA1L as a cellular prion protein stabilizer in tumor progression via HIF-1α/GP78 axis

The cellular prion protein (PrP^C) is associated with metastasis, tumor progression and recurrence; however, the precise mechanisms underlying its action is not well understood. Our study found that PrP^C degradation decreased tumor progression in colorectal cancer (CRC). In a CRC cell line and human CRC tissue exposed to hypoxia, induced heat-shock 70-kDa protein-1-like (HSPA1L) expression stabilized hypoxia-inducible factor-1α (HIF-1α) protein and promoted PrP^C accumulation and tumorigenicity in vivo. PrP^C was degraded via the proteasome pathway mediated by the ubiquitin-protein E3 ligase glycoprotein 78 (GP78), which interacts directly with PrP^C. However, hypoxia-induced HSPA1L interacted with GP78 and inhibited its functions. HSPA1L knockdown facilitated the interaction of GP78 and PrP^C, thereby increasing PrP^C ubiquitination. Thus, GP78 was identified as the ubiquitinase for PrP^C, thereby revealing an essential mechanism that controls PrP^C levels in CRC. Our results suggest that the HSPA1L/HIF-1α/GP78 axis has a crucial role in PrP^C accumulation during tumor progression.

OCT4 spliced variants are highly expressed in brain cancer tissues and inhibition of OCT4B1 causes G2/M arrest in brain cancer cells

The new claim about the origin of cancer known as Cancer Stem Cell theory states that a somatic differentiated cell can dedifferentiated or reprogrammed for regaining the cancer cell features. It has been recently shown that expression of stemness factors such as Oct4, Sox2, Nanog and Klf4, in a variety of somatic cancers can leads to development of tumorogenesis. Here, the expression of Oct4 variants were evaluated in brain tumor tissues by quantitative RT-PCR and immunohistochemical (IHC) analysis. In next phase of our study, the expression of Oct4B1 was knock-down in brain cancer cell lines and its effect on cell cycle was assessed. Finally, in order to get insights into sequence-structure-function relationships of Oct4 isofroms, their sequences were analysed using bioinformatic tools. Our data revealed that all three variants of Oct4 are expressed in different types of brain cancer. The expression level of Oct4B1, in contast to Oct4B, was much higher in high-grade brain tumors compared with low-grade ones. In line with qPCR, the expression of Oct4A and B isofroms was confirmed with IHC in different types of brain tumors. Moreover, as a result of the suppression of Oct4B1 expression, the brain cancer cells were arrested in G2/M phase of cell cycle. Bioinfromatics data indicated that the predicted Oct4B1 protein have DNA binding properties. All together, our findings suggest that Oct4B1 has a potential role in tumorigenesis of brain cancer and can be considered as a new tumor marker with potential value in diagnosis and treatment of brain cancer.