CD109 Mediates Cell Survival in Hepatocellular Carcinoma Cells

Insights Into the Hematopoietic Regulatory Activities of Osteoblast by Secretomics

Osteoblasts are a key component of the endosteal hematopoietic stem cell niche and are recognized with strong hematopoietic supporting activity. Similarly, mesenchymal stromal cells (MSC)-derived osteoblast (M-OST) conditioned media (OCM) enhance the growth of hematopoietic progenitors in culture and modulate their engraftment activity. This article aims to characterize the hematopoietic supporting activity of OCM by comparing the secretome of M-OST to that of their precursor. Over 300 proteins are quantified by mass spectroscopy in media conditioned with MSC or M-OST, with 47 being differentially expressed. Growth factors, extracellular matrix proteins, and proteins from the complement pathways are included. The functional contribution of selected proteins on the growth and differentiation of cord blood (CB) progenitors is tested. Secreted protein acidic and rich in cysteine and Galectin 3 (Gal3) have little impact on the growth of CB cells in serum-free medium (SFM). In contrast, inhibition of the complement 3A receptor (C3a-R) present on CB progenitors significantly reduces the growth of CD34+ cells in OCM cultures but not in SFM. These results provide new insights into changes in factors released by MSC undergoing osteoblast differentiation, and on paracrine factors that are partially responsible for the hematopoietic supporting activity of osteoblasts.

CD109 mediates tumorigenicity and cancer aggressiveness via regulation of EGFR and STAT3 signalling in cervical squamous cell carcinoma

Background

CD109 was involved in the tumorigenesis and progression of various cancers via TGF-β1 signalling and STAT3 activation. As CD109 is strongly expressed in cervical squamous cell carcinoma, this study was conducted to investigate its functional characteristics in cervical cancer.

Methods

CD109 expression was examined by immunohistochemistry (IHC) with cervical tissue microarray. The effects of CD109 expression were examined on migration, cell proliferation, spheroid formation and soft-agar colony-formation assay. Meanwhile, cervical cancer cell lines with high CD109 expression were chosen for the functional study using siRNA knockdown and CRISPR/Cas9 knockout.

Results

IHC demonstrated an upregulation of CD109 in the cell membrane of cervical squamous cell carcinoma. CD109( + ) cells isolated by flow-cytometric sorting displayed enhanced migration, cell proliferation, sphere-forming and anchorage-independent cell growth ability. In contrast, silencing of CD109 expression could reverse the in vitro and in vivo tumorigenic and aggressive properties. Furthermore, CD109 induced EGFR-mediated STAT3 phosphorylation known to be responsible for cell migration, proliferation and maintenance of CSC phenotype.

Conclusion

Abundant CD109( + ) populations in cervical cancer cells potentially contributed to carcinogenesis and aggressiveness, whereas silencing of CD109 expression could reverse those properties. CD109 mediates cervical tumorigenicity and aggressiveness via CD109/EGFR/STAT3 signalling.

Elevation of CD109 promotes metastasis and drug resistance in lung cancer via activation of EGFR-AKT-mTOR signaling

Lung cancer is the most commonly diagnosed cancer worldwide, and metastasis in lung cancer is the leading cause of cancer‐related deaths. Thus, understanding the mechanism of lung cancer metastasis will improve the diagnosis and treatment of lung cancer patients. Herein, we found that expression of cluster of differentiation 109 (CD109) was correlated with the invasive and metastatic capacities of lung adenocarcinoma cells. CD109 is upregulated in tumorous tissues, and CD109 overexpression was associated with tumor progression, distant metastasis, and a poor prognosis in patient with lung adenocarcinoma. Mechanistically, expression of CD109 regulates protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling via its association with the epidermal growth factor receptor (EGFR). Inhibition of CD109 decreases EGFR phosphorylation, diminishes EGF‐elicited activation of AKT/mTOR, and sensitizes tumor cells to an EGFR inhibitor. Taken together, our results show that CD109 is a potential diagnostic and therapeutic target in lung cancer patients.

Development of novel monoclonal antibodies against CD109 overexpressed in human pancreatic cancer

Pancreatic cancer is one of the most aggressive and lethal types of cancer, and more effective therapeutic agents are urgently needed. Overexpressed cell surface antigens are ideal targets for therapy with monoclonal antibody (mAb)-based drugs, but none have been approved for the treatment of pancreatic cancer. Here, we report development of two novel mouse mAbs, KU42.33C and KU43.13A, against the human pancreatic cancer cell line BxPC-3. Using ELISA, flow cytometry, competitive assay and immunoprecipitation followed by mass spectrometry, we discovered that these two mAbs target two distinct epitopes on the external domain of CD109 that are overexpressed by varying amounts in human pancreatic cancer cell lines. Treatment with these two naked antibodies alone did not affect tumour cell growth or migration in vitro. Of the two mAbs, only KU42.33C was useful in determining the expression of CD109 in tumour cells by Western blot and immunohistochemistry. Interestingly, immunohistochemistry of human pancreatic carcinoma tissue arrays with mAb KU42.33C showed that 94% of the 65 human pancreatic adenocarcinoma cases were CD109 positive, with no expression in normal pancreatic tissues. Our results suggest that these two novel mAbs are excellent tools for determining the expression level of CD109 in the tumour specimens and sera of patients with a wide range of cancers, in particular pancreatic cancer, and for investigating its diagnostic, prognostic and predictive value. Further research is warranted and should aim to unravel the therapeutic potential of the humanised forms or conjugated versions of such antibodies in patients whose tumours overexpress CD109 antigen.

Specific expression of proton-coupled oligopeptide transporter 1 in primary hepatocarcinoma-a novel strategy for tumor-targeted therapy

Proton-coupled oligopeptide transporter 1 (PEPT1) is a membrane protein which expressed predominantly in intestine and recognized as the target of dietary nutrients (di/tripeptide) or peptidomimetic drug for delivery. The information on the existence of PEPT1 in carcinomas were limited. Our study aimed to investigate the expression profile and transport activity of PEPT1 both in human hepatocarcinoma tissues and cell lines. Western blotting and an immunofluorescence assay revealed the high level of PEPT1 protein expression in hepatocarcinoma Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cell lines. Quantitative real time PCR showed the mRNA expression of PEPT1 in Bel-7402, SMMC-7721, HepG2, HEP3B, SK-HEP-1 cells. High level PEPT1 expression in hepatocarcinoma patient samples were observed by Immunohistology and showed a significant correlation between protein level and pathological grade. Functional activities were also studied using D-Ala-Lys-AMCA (a substrate of peptide transporter) in above five hepatocarcinoma cell lines. The uptake tests performed by fluorescent microscopy suggested that PEPT1 can transport both D-Ala-Lys-AMCA into the hepatocarcinoma cells and the uptake can be competitively inhibited by three PEPT1 substrates (Gly-sar, Gly-gln and Glyglygly). In conclusion, our findings provided the novel information on the expression and function of PEPT1 in human hepatocarcinoma and expanded the potential values for tumor specific drug delivery.