Plasma soluble podoplanin is a novel marker for the diagnosis of tumor occurrence and metastasis

Abstract

Podoplanin (PDPN) is expressed on many tumors and is involved in tumor metastasis. The objective of the present study was to develop an ELISA for determining soluble PDPN (sPDPN) levels as a potential novel tumor marker in plasma of patients with cancers for detection of tumor occurrence and metastasis. Mouse monoclonal antibodies (mAb) against human PDPN were developed and characterized. Two anti‐PDPN mAb, SZ‐163 and SZ‐168, were used in a sandwich ELISA to detect plasma sPDPN in patients with cancers and in normal individuals. The levels of sPDPN were detected in patients with adenocarcinoma (87 cases, 31.09 ± 5.48 ng/ml), squamous cell carcinoma (86 cases, 6.91 ± 0.59 ng/ml), lung cancer (45 cases, 26.10 ± 7.62 ng/ml), gastric cancer (38 cases, 23.71 ± 6.90 ng/ml) and rectal cancer (27 cases, 32.98 ± 9.88 ng/ml), which were significantly higher than those in normal individuals (99 cases, 1.31 ± 0.13 ng/ml) (P < .0001). Moreover, the sPDPN levels in patients with metastatic cancers were higher (192 cases, 30.35 ± 3.63 ng/ml) than those in non‐metastatic cancer patients (92 cases, 6.28 ± 0.77 ng/ml) (P < .0001). The post‐treatment sPDPN levels of cancer patients (n = 156) (4.47 ± 0.35 ng/ml) were significantly lower compared with those seen pre‐treatment (n = 128) (43.74 ± 4.97 ng/ml) (P < .0001). These results showed that an ELISA method was successfully established for quantitation of plasma sPDPN and plasma sPDPN levels correlate significantly with tumor occurrence and metastasis.

Podoplanin in Inflammation and Cancer

“…In bladder cancer, higher levels of soluble podoplanin in the serum of patients are associated with larger and more aggressive multifocal tumors [164]. Likewise, the levels of soluble podoplanin in plasma were found to increase in patients with a wide variety of cancers compared to normal individuals, as well as in patients with metastasis with respect to patients with non-metastatic tumors [165]. Interestingly, the levels of soluble podoplanin were reduced after treatment of patients with chemotherapy or surgery followed by chemotherapy, pointing to soluble podoplanin as a specific cancer biomarker [165].…”

Blocking podoplanin suppresses growth and pulmonary metastasis of human malignant melanoma

“…Our previous study found that SZ163 and SZ168 detected hPDPN in CHO/hPDPN, NCI-H226, and U87 cells but not CHO cells [24], indicating that SZ163 and SZ168 specifically recognize hPDPN. Flow cytometry assay showed that SZ163 and SZ168 also detected endogenous PDPN in the human cancer cell lines C8161 and CNE-2, similarly to the 18H5 as positive control antibody (Fig.…”

“…SZ163 and SZ168, two mouse anti-hPDPN mAbs, were developed as described previously [24]. A mouse anti-hPDPN mAb (18H5), a normal mouse IgG (ab188776), and a rabbit anti-hPDPN mAb (EPR7072) were purchased from Abcam (Cambridge, UK).…”

“…Flow cytometry was performed as previously described [24]. Cultured cells were harvested by brief exposure to trypsin-ethylenediaminetetraacetic acid (EDTA) treatment and then incubated with 18H5 as a positive control, mouse IgG as a negative control, or anti-PDPN antibodies (SZ163 and SZ168, 2 μg) for 30 min at room temperature, followed by FITC-GAM IgG as secondary antibody for 30 min at room temperature.…”

“…We have produced mAbs (SZ163 and SZ168) against the extracellular domain of human PDPN, and both exhibited high specificity and sensitivity [24]. An SZ163/SZ168-double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantitate plasma-soluble PDPN in cancer patients and evaluate the correlation between PDPN and tumor occurrence and metastasis [24], although it is unknown whether SZ163 and SZ168 inhibit the growth and metastases in PDPN-expressing human tumors.…”