Prohaptoglobin is a possible prognostic biomarker for colorectal cancer.

BACKGROUND AND AIMS: Fucosylated haptoglobin is a novel glycan biomarker for colorectal and other cancers, while the significance of its precursor, prohaptoglobin (proHp), remains to be elucidated. In this study, we investigated whether proHp can be a colorectal cancer (CRC) biomarker and the biological functions of proHp in CRC using 10-7G, a monoclonal antibody recently developed in our laboratory. MATERIALS AND METHODS: Serum proHp level in 74 patients with CRC was semi-quantified by western blotting, and 5-year recurrence-free survival and overall survival were analyzed for groups stratified by proHp status (high vs. low). We also performed immunohistochemical analyses of 17 CRC tissue sections using 10-7G mAb. The biological functions of proHp were evaluated by overexpressing proHp in CRC cell lines. RESULTS: Serum proHp correlated with the clinical stage and poorer prognosis of CRC. In the primary CRC sections, immune cells were stained positive for 10-7G in ∼50% of the cases. Overexpression of proHp in HCT116 human CRC cells induced epithelial-mesenchymal transition-like changes and promoted cell migration in CRC cells. CONCLUSION: We provide evidence for the first time that proHp has potential as a prognostic biomarker for CRC and demonstrated specific biological activities of proHp.

Rapid Chemical Synthesis of Serine Protease Inhibitor Kazal-type 13 (SPINK13) Glycoform by a Combined Method with Glycan Insertion Strategy and Fast-Flow Fmoc SPPS.

Serine protease inhibitor Kazal type 13 (SPINK13) is a secreted protein that has been recently studied as a therapeutic drug and an interesting biomarker for cancer cells. Although SPINK13 has a consensus sequence (Pro-Asn-Val-Thr) for N-glycosylation, the existence of N-glycosylation and its functions are still unclear. In addition to this, the preparation of glycosylated SPINK 13 has not been examined by both the cell expression method and chemical synthesis. Herein we report the chemical synthesis of the scarce N-glycosylated form of SPINK13 by a rapid synthetic method combined with the chemical glycan insertion strategy and a fast-flow SPPS method. Glycosylated asparagine thioacid was designed to chemoselectively be inserted between two peptide segments where is the sterically bulky Pro-Asn(N-glycan)-Val junction by two coupling reactions which consist of diacyl disulfide coupling (DDC) and thioacid capture ligation (TCL). This insertion strategy successfully afforded the full-length polypeptide of SPINK13 within two steps from glycosylated asparagine thioacid. Because the two peptides used for this synthesis were prepared by a fast-flow SPPS, the total synthetic time of glycoprotein was considerably shortened. This synthetic concept enables us to repetitively synthesize a target glycoprotein easily. Folding experiments afforded well-folded structure confirmed by CD and disulfide bond map. Invasion assays of glycosylated SPINK13 and non-glycosylated SPINK13 with pancreatic cancer cells showed that non-glycosylated SPINK-13 was more potent than that of glycosylated SPINK13.

Prognostic significance of serum fucosylated pro-haptoglobin in advanced renal cell carcinoma patients treated with immune checkpoint inhibitors.

With the widespread use of immune checkpoint inhibitors (ICIs), identifying predictive biomarkers is critical. Recently, serum fucosylated haptoglobin (Fuc-Hp) was thought to play an important role in tumour immunity in several types of cancer. Therefore, evaluating serum Fuc-Hp in the peripheral blood can potentially identify non-invasive predictive biomarkers for the clinical efficacy of ICIs. In this study, 31 patients with advanced renal cell carcinoma (RCC) treated with nivolumab were enrolled and defined as responders or non-responders according to RECIST criteria. Serum samples were collected before and 1 month after treatment initiation, and an ELISA assay was performed using Aleuria Aurantia Lectin (AAL) and 10-7G monoclonal antibodies that recognise Fuc-mature Hp (Fuc-mHp) and Fuc-pro Hp (Fuc-pHp), respectively. We first measured AAL-haptoglobin (Fuc-mHp) and total haptoglobin levels before nivolumab and found that neither value could predict the clinical response. Notably, serum 10-7G levels were significantly lower in the responder group (p = 0.035). We also confirmed the use of serum 10-7G levels for predicting progressive disease after nivolumab (area under the curve, 0.816). Accordingly, low 10-7G levels were significantly correlated with better progression-free survival (p = 0.041). In conclusion, serum Fuc-pHp analysis may identify patients with advanced RCC who benefit from ICIs.

Transcription factor SP1 regulates haptoglobin fucosylation via induction of GDP-fucose transporter 1 in the hepatoma cell line HepG2.

Fucosylation is involved in cancer and inflammation, and several fucosylated proteins, such as AFP-L3 for hepatocellular carcinoma, are used as cancer biomarkers. We previously reported an increase in serum fucosylated haptoglobin (Fuc-Hp) as a biomarker for several cancers, including pancreatic and colon cancer and hepatocellular carcinoma. The regulation of fucosylated protein production is a complex cellular process involving various fucosylation regulatory genes. In this report, we investigated the molecular mechanisms regulating Fuc-Hp production in cytokine-treated hepatoma cells using a partial least squares (PLS) regression model. We found that SLC35C1, which encodes GDP-fucose transporter 1 (GFT1), is the most responsible factor for Fuc-Hp production among various fucosylation regulatory genes. Furthermore, the transcription factor SP1 was essential in regulating SLC35C1 expression. We also found that an SP1 inhibitor was able to suppress Fuc-Hp production without affecting total Hp levels. Taken together, Fuc-Hp production was regulated by SP1 via induction of GFT1 in the hepatoma cell line HepG2.