Progressive Enrichment of Stemness Features and Tumor Stromal Alterations in Multistep Hepatocarcinogenesis.

Jeong Eun Yoo,Massimo Roncalli,Jin Sub Choi,Young Nyun Park,Haeryoung Kim,Ei Yong Ahn,Young-Joo Kim,Hyungjin Rhee,Taro Yamashita

doi:10.1371/journal.pone.0170465

Jeong Eun Yoo, Massimo Roncalli + Show 7 more

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https://doi.org/10.1371/journal.pone.0170465

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Abstract

Cancer stem cells (CSCs), a subset of tumor cells, contribute to an aggressive biological behavior, which is also affected by the tumor stroma. Despite the role of CSCs and the tumor stroma in hepatocellular carcinoma (HCC), features of stemness have not yet been studied in relation to tumor stromal alterations in multistep hepatocarcinogenesis. We investigated the expression status of stemness markers and tumor stromal changes in B viral carcinogenesis, which is the main etiology of HCC in Asia. Stemness features of tumoral hepatocytes (EpCAM, K19, Oct3/4, c-KIT, c-MET, and CD133), and tumor stromal cells expressing α-smooth muscle actin (α-SMA), CD68, CD163, and IL-6 were analyzed in 36 low grade dysplastic nodules (DNs), 48 high grade DNs, 30 early HCCs (eHCCs), and 51 progressed HCCs (pHCCs) by immunohistochemistry or real-time PCR. Stemness features (EpCAM and K19 in particular) were progressively acquired during hepatocarcinogenesis in combination with enrichment of stromal cells (CAFs, TAMs, IL-6+ cells). Stemness features were seen sporadically in DNs, more consistent in eHCCs, and peaked in pHCCs. Likewise, stromal cells were discernable in DNs, showed up as consistent cell densities in eHCCs and peaked in pHCCs. The stemness features and tumor stromal alterations also peaked in less differentiated or larger HCCs. In conclusion, progression of B viral multistep hepatocarcinogenesis is characterized by an enrichment of stemness features of neoplastic hepatocytes and a parallel alteration of the tumor stroma. The modulation of neoplastic hepatocytes and stromal cells was at low levels in precancerous lesions (DNs), consistently increased in incipient cancer (eHCCs) and peaked in pHCCs. Thus, in B viral hepatocarcinogenesis, interactions between CSCs and the tumor stroma, although starting early, seem to play a major role in tumor progression.

Highlights

Cancer stem cells (CSCs), a subset of tumor cells, exhibit the ability to self-renew and initiate tumor formation, and they contribute to rapid tumor growth and chemoresistance [1]
The protein expression levels of epithelial cell adhesion molecule (EpCAM), K19, and CD133 gradually increased with progression from low grade dysplastic nodules (LGDNs), high grade DNs (HGDNs), and early hepatocellular carcinomas (HCCs) (eHCCs) to progressed HCCs (pHCCs) with statistical significance: stemness markers were seen sporadically in dysplastic nodules (DNs), more consistent in eHCC and peaking in pHCCs (P
According to the size of HCCs, EpCAM and K19 protein expression levels were significantly higher in large HCCs (>2 cm) than in small HCCs ( 2 cm) (Fig 3C), while there were no significant differences in CD133 status according to size

Summary

Introduction

Cancer stem cells (CSCs), a subset of tumor cells, exhibit the ability to self-renew and initiate (promote) tumor formation, and they contribute to rapid tumor growth and chemoresistance [1]. The biological behavior of tumors is known to be affected by the tumor cells themselves and by their interactions with the adjacent stroma [4]. The tumor stroma consists of several cellular components, including cancer-associated fibroblasts (CAFs) ( known as myofibroblasts), tumor-associated macrophages (TAMs), cell signaling molecules, extracellular matrix proteins, and blood vessels [5]. CAFs have been reported to promote tumor growth and invasion and to stimulate angiogenesis, and associations between CAFs and aggressive biological behavior, poor prognosis, and chemoresistance have been demonstrated in various malignancies including HCC [6]. TAMs are responsible for mediating the wound healing processes via extracellular matrix remodeling, angiogenesis, and immunosuppression [7], and they were reported to be correlated with worse prognosis in various cancers, including HCC [8]. IL-6, a multifunctional inflammatory cytokine produced by CAFs and TAMs, has been shown to play important roles in tumor progression [9]

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