Elsevier

Matrix Biology

Volume 98, April 2021, Pages 21-31
Matrix Biology

Heparanase 2 (Hpa2) attenuates the growth of pancreatic carcinoma

https://doi.org/10.1016/j.matbio.2021.03.002Get rights and content

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  • Our findings indicate that Hpa2 attenuates pancreatic tumor growth and highlight a feedback mechanism by which Hpa2 enhances ER stress which, in turn, induces Hpa2 expression. This results in consistent and severe ER stress, leading to increased apoptotic cell death and attenuated tumor growth. Thus, compounds designed to elicit ER stress may turn beneficial therapeutics in pancreatic cancer.

  • Hpa2 attenuates pancreatic tumor growth by exerting a feedback mechanism where Hpa2 enhances ER stress that, in turn, induces Hpa2 expression.

  • This results in consistent and severe ER stress, leading to increased apoptotic cell death and attenuated tumor growth.

  • Compounds designed to elicit ER stress may turn beneficial therapeutics in pancreatic cancer.

Abstract

While the pro-tumorigenic properties of the ECM-degrading heparanase enzyme are well documented, the role of its close homolog, heparanase 2 (Hpa2), in cancer is largely unknown. We examined the role of Hpa2 in pancreatic cancer, a malignancy characterized by a dense fibrotic ECM associated with poor response to treatment and bad prognosis. We show that pancreatic ductal adenocarcinoma (PDAC) patients that exhibit high levels of Hpa2 survive longer than patients with low levels of Hpa2. Strikingly, overexpression of Hpa2 in pancreatic carcinoma cells resulted in a most prominent decrease in the growth of tumors implanted orthotopically and intraperitoneally, whereas Hpa2 silencing resulted in bigger tumors. We further found that Hpa2 enhances endoplasmic reticulum (ER) stress response and renders cells more sensitive to external stress, associating with increased apoptosis. Interestingly, we observed that ER stress induces the expression of Hpa2, thus establishing a feedback loop by which Hpa2 enhances ER stress that, in turn, induces Hpa2 expression. This leads to increased apoptosis and attenuated tumor growth. Altogether, Hpa2 emerges as a powerful tumor suppressor in pancreatic cancer.

Introduction

Heparanase is an endo-beta-glucuronidase capable of cleaving heparan sulfate (HS) side chains of heparan sulfate proteoglycans (HSPG). This activity results in remodeling of the extracellular matrix (ECM) and enhances cell dissemination associated with tumor metastasis and transmigration of immune cells [1], [2], [3], [4]. Compelling evidence gathered in the last two decades tie heparanase not only with tumor metastasis but with all aspects of cancer progression namely tumor initiation, growth, metastasis, and chemoresistance [3,[5], [6], [7]]. Also, heparanase was noted to orchestrate a cross-talk between tumor cells and the tumor microenvironment [8], [9], [10], [11], [12], [13] and to support stemness [14], thus encouraging the development of heparanase inhibitors as anti-cancer drugs [3,6,7,[15], [16], [17]]. Heparanase 2 (Hpa2) is a close homolog of heparanase [18]; it lacks HS-degrading activity typical of heparanase, yet retains the high-affinity interaction with HS [19]. Unlike the intense research effort devoted to exploring the significance of heparanase in human diseases, very little attention was given to Hpa2. Notably, in head and neck cancer high levels of Hpa2 are associated with prolonged patients survival and decreased tumor cell dissemination to regional lymph nodes [19], suggesting that Hpa2 functions as a tumor suppressor. Here, we examined the role of Hpa2 in pancreatic cancer, a malignancy characterized by a dense fibrotic ECM associated with poor response to treatment and exceedingly bad prognosis. We found that patients who show high levels of Hpa2 survive longer than patients with low levels of Hpa2. Likewise, overexpression of Hpa2 in pancreatic carcinoma cells resulted in a most prominent decrease in tumor growth (orthotopic and intra-peritoneal) whereas Hpa2 silencing resulted in bigger tumors. We further found that Hpa2 elicits endoplasmic reticulum (ER) stress and increased apoptotic cell death. Importantly, ER stress induces the expression of Hpa2, thus establishing a loop that feeds itself. This loop, and the higher sensitivity of Hpa2-overexpressing cells to stress conditions, likely leads to attenuated tumor growth.

Section snippets

Hpa2 attenuates pancreatic tumor growth

To reveal the role of Hpa2 in pancreatic cancer we subjected a cohort of PDAC biopsies (Table 1) to immunostaining applying anti-Hpa2 antibody. No, or very weak staining of Hpa2 was detected in normal ducts and exocrine cells in normal pancreatic tissue adjacent to the tumor lesion (Fig. 1A, upper left panel), whereas pancreatic beta cells in Langerhans islets were stained positive. These positively-stained islets are found in the normal pancreas tissue adjacent to the tumor lesion (Fig. 1A,

Discussion

While the pro-tumorigenic properties of heparanase are well-taken [3,6,15,23], the role of Hpa2 in cancer is largely unknown. Unlike heparanase, Hpa2 staining is readily detected in the normal epithelium of the bladder, breast, gastric and ovarian tissues. Notably, Hpa2 levels are decreased substantially in the resulting carcinomas [20,[24], [25], [26]], a staining pattern typical of a tumor suppressor. Moreover, high levels of Hpa2 associate with prolonged survival of head and neck cancer

Conclusions

Our findings indicate that Hpa2 attenuates pancreatic tumor growth and highlight a feedback mechanism by which Hpa2 enhances ER stress which, in turn, induces Hpa2 expression. This results in consistent and severe ER stress, leading to increased apoptotic cell death and attenuated tumor growth. Thus, compounds designed to elicit ER stress may turn beneficial therapeutics in pancreatic cancer.

Cells, cell culture, and immunoblotting

Human Panc-01, Capan-1, and CFPAC-1 pancreatic carcinoma cells were purchased from the ATCC; mouse Panc-02 cells have been described previously [13]. Cells were grown in Dulbecco's modified Eagle's medium (Biological Industries, Beit Haemek, Israel) supplemented with 10% fetal bovine serum and antibiotics. The human cell lines were authenticated in June 2020 by the short tandem repeat (STR) profile of 15 loci plus amelogenin for sex determination (X or XY) method, according to the

Declaration of Competing Interest

The authors declare no conflict of interest.

Funding

These studies were generously supported by research grants awarded by the Israel Science Foundation (ISF grant 1021/19), and the Israel Cancer Research Fund (ICRF). I. Vlodavsky is a Research Professor of the ICRF.

Author contribution

Conception and design of the work- IV, NI,

Acquisition, analysis, or interpretation of data-YK, PS, IN, NI

Drafted the work or substantively revised it-NI, IV

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    Conclusions: Our findings indicate that Hpa2 attenuates pancreatic tumor growth and highlight a feedback mechanism by which Hpa2 enhances ER stress which, in turn, induces Hpa2 expression, leading to increased tumor cell death.

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