Inhibitory effects of the recombinant human serine protease inhibitor Hespintor on the proliferation, migration and invasion of hepatocellular carcinoma cells

Hespintor Negative Regulation of PI3K/Akt Pathway Induces Cell Cycle Arrest of Hepatocellular Carcinoma

The mechanism of Hespintor (a protein of serpin family) inhibitory action on the growth of inoculated hepatocellular carcinoma was studied in a model of human hepatoma in nude mice by using on long-noncoding RNA (lncRNA) sequencing. Two days after tumor transplantation, Hespintor or normal saline was injected into the caudal vein at a dose of 15 μg/kg (2 times a week over 4 weeks). The tumors were isolated in 4 weeks after subcutaneous injection of human hepatoma MHCC97-H cells. In Hespintor and control groups, the complementary DNA libraries of tumor tissues were established, and transcriptome sequencing was performed. Based on RNA-sequencing data, the differentially expressing lncRNA genes (DEGs lncRNA) were obtained, and functional enrichment and interaction analyses were performed to find the regulatory gene sets. Then, the network module division method was employed to identify the key genes of the Hespintor action, as well as to build the regulatory network and critical pathways associated with the key genes with validation of the results by Western blotting. The target gene sets regulated by DEGs lncRNA were mainly enriched in cell behavior, transcriptional regulation, and cell cycle. The PI3K/Akt signaling pathway related to the revealed gene sets plays a leading role in the antitumor action of Hespintor, targeted by this serpin to down-regulate expression levels of the cell cycle regulatory proteins Cyclin D1, P-Rb, CDK4, and CDK6, thereby arresting the cell cycle in G1/S phase.

SPINK13 acts as a tumor suppressor in hepatocellular carcinoma by inhibiting Akt phosphorylation

The PI3K/Akt pathway is overexpressed in nearly 50% of hepatocellular carcinomas and inhibits apoptosis by promoting the expression of antiapoptotic genes. Serine protease inhibitors have been shown to induce apoptosis in hepatoma cells by downregulating SPINK13 in the PI3K/Akt pathway. In this study, SPINK13 was expressed in lentiviral vectors. Changes in signaling pathway adapter proteins, apoptosis regulatory proteins, cell cycle regulatory proteins, and the biological behavior of hepatocellular carcinoma were observed in cell and nude mouse xenograft models. The underlying mechanism of endogenous SPINK13-induced apoptosis in hepatocellular carcinoma cells was explored via transcriptomics. As a result, endogenous SPINK13 might inhibit the activity of Furin protease, downregulate the Notch1/Hes1 pathway in a binding manner, activate the direct effector PTEN, inhibit Akt phosphorylation, inactivate the downstream PI3K/Akt pathway, and ultimately lead to mitochondrial apoptosis and cell cycle arrest in hepatoma cells. Therefore, the Notch1/Hes1/PTEN pathway may act upstream of SPINK13 to downregulate the PI3K/Akt signaling pathway. Our study helps elucidate the underlying mechanism of SPINK13 in anti-hepatocellular carcinoma and lays a theoretical foundation for the development of novel therapeutic serine protease inhibitors.

Transcriptome analysis of the effect of a novel human serine protease inhibitor SPINK13 on gene expression in MHCC97-H cells

BACKGROUND

Serine peptidase inhibitor, Kazal type 13 (SPINK13) (also known as hespinter) is a low-molecular-weight inhibitor of uPA that was discovered in 2006. It was detected in prokaryotic cells in 2013 for the first time and preliminarily shown to inhibit hepG2 liver cancer cells growth in vitro in 2015. In this study, the differentially transcribed genes of MHCC97-H cells caused by SPINK13 treatment were studied by transcriptomics and the molecular mechanism of SPINK13 suppressing tumor cells was proposed using bioinformatics.

METHODS

Preliminary study of the molecular mechanism of SPINK13's anti-cancer effect was performed by identifying potential target sites and signal pathways of SPINK13 through transcriptomics and bioinformatics analysis.

RESULTS

The results of the transcriptome study showed that there were 446 significantly differentially expressed genes between the experimental group and the blank control group, of which 347 genes were up-regulated and 99 genes were down-regulated. The Gene Ontology (GO) analysis showed that differentially expressed genes were enriched in cell growth regulation and cell division. They were enriched in the signal pathways of tumor transcription and cell cycle by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis; there were 6 classical tumor signaling pathways (P<0.001): MAPK, apoptosis, tumor necrosis factor (TNF), cell cycle, p53, and transcriptional misregulation in cancer. There were 8 genes in 2 or more classical tumor signaling pathways at the same time: JUN, GADD45A, GADD45B, TNFRSF1A, FOS, CDKN1B, NFKBIA, and BBC3. The interaction analysis of the proteins encoded by the differentially expressed genes showed that there were 35 interaction nodes in the up-regulated genes and 2 interaction nodes in the down-regulated genes.

CONCLUSIONS

This study showed that SPINK13 inhibits hepatocellular carcinoma cell development by regulating the JNK, p53, and the IKK/NF-κB pathways, its potential targets for antitumor drugs may be JUN, GADD45A, GADD45B, TNFRSF1A, FOS, CDKN1B, NFKBIA, and BBC3.

The Inhibitory Effects of Recombinant Hespintor Combined with Sorafenib on Transplanted Human Hepatoma in Nude Mice, and Transcriptional Regulation of Hespintor Based on RNA-Seq

Objective: As targeted drugs, exogenous serpins could be introduced to patients to restore body balance. This study aimed to observe further the inhibitory effects of recombinant Hespintor (a Kazal-type serpin) combined with Sorafenib on transplanted human hepatoma tumors in nude mice specimens and to explore the possible transcriptional regulation by Hespintor. Methods: A model of human hepatoma tumors transplanted in nude mice was established, and the medication was administrated to observe the growth of the tumors. Four weeks after the drug administration, the tumors were removed to evaluate the inhibition effects of Hespintor on in-situ tumor growth and liver metastasis. The expression levels of MMP2, MMP9, Bax, Bcl-2, and caspase-3 in the tumor organizations were detected with Western blot. The target genes of the Hespintor were screened based on tissue RNA-Seq, and the regulatory network was constructed. Results: It was found that the recombinant Hespintor displayed a significant antitumor effect on the subcutaneous growth of MHCC97-H cells. Moreover, the therapeutic effects of the combination therapy were significantly better than those of single therapy. 10 target genes with significantly different expression by Hespintoron tumor tissue were identified. Finally, a visual regulatory networkwas constructed for target mRNA-pathway. Conclusions: The antitumor effect of Hespintor combined with Sorafenib in treating the subcutaneously implanted hepatocellular carcinoma tumors in nude mice was significant. The possible transcriptional regulation by Hespintor involved multiple signaling pathways, and it was not just the antitumor effect of uPA via its extracellular inhibitions.

Novel urokinase-plasminogen activator inhibitor SPINK13 inhibits growth and metastasis of hepatocellular carcinoma in vivo

Advanced hepatocellular carcinoma (HCC) is a highly aggressive malignancy that is a serious threat to the public health system of China. Urokinase-plasminogen activator (uPA) can promote the invasive growth and metastasis of HCC cells by activating matrix metalloproteinases (MMPs), leading to the breakage of the extra-cellular matrix. uPA is a promising target for advanced HCC treatment. In this stuy the expression of uPA was examined by quantitative polymerase chain reaction in hepatic cell lines. Protein interaction between uPA and SPINK13 was identified by immunoprecipitation. In vitro biochemical assay was used to examine the inhibitory effect of the SPINK13 on the direct cleaving of the recombinant pro-MMP9 by uPA. The antitumor effect of SPINK13 was examined by transwell assay or the nude mice tumor model.The expression of uPA was much higher in highly aggressive HCC cell lines than in lowly aggressive HCC cell lines or non-tumor hepatic cell lines. SPINK13 interacted with uPA in HCC cells and directly inhibited the cleaving of MMP9 by uPA. Treatment of the recombinant SPINK13 protein inhibited the invasion of HCC cells in several experiments, such as transwell experiments or the intrahepatic growth model. The results of the study indicated that SPINK13 could function as a promising therapeutic approach for patients with advanced HCC.

Selective depletion of tumour suppressors Deleted in Colorectal Cancer (DCC) and neogenin by environmental and endogenous serine proteases: linking diet and cancer

BACKGROUND

The related tumour suppressor proteins Deleted in Colorectal Cancer (DCC) and neogenin are absent or weakly expressed in many cancers, whereas their insertion into cells suppresses oncogenic behaviour. Serine proteases influence the initiation and progression of cancers although the mechanisms are unknown.

METHODS

The effects of environmental (bacterial subtilisin) and endogenous mammalian (chymotrypsin) serine proteases were examined on protein expression in fresh, normal tissue and human neuroblastoma and mammary adenocarcinoma lines. Cell proliferation and migration assays (chemoattraction and wound closure) were used to examine cell function. Cells lacking DCC were transfected with an ectopic dcc plasmid.

RESULTS

Subtilisin and chymotrypsin selectively depleted DCC and neogenin from cells at nanomolar concentrations without affecting related proteins. Cells showed reduced adherence and increased migration, but after washing they re-attached within 24 h, with recovery of protein expression. These effects are induced by chymotryptic activity as they are prevented by chymostatin and the soybean Bowman-Birk inhibitor typical of many plant protease inhibitors.

CONCLUSIONS

Bacillus subtilis, which secretes subtilisin is widely present in soil, the environment and the intestinal contents, while subtilisin itself is used in meat processing, animal feed probiotics and many household cleaning agents. With chymotrypsin present in chyme, blood and tissues, these proteases may contribute to cancer development by depleting DCC and neogenin. Blocking their activity by Bowman-Birk inhibitors may explain the protective effects of a plant diet. Our findings identify a potential non-genetic contribution to cancer cell behaviour which may explain both the association of processed meats and other factors with cancer incidence and the protection afforded by plant-rich diets, with significant implications for cancer prevention.