Prevention of Hepatocellular carcinoma progression by the Chinese herb derived peptide Lingzhi-8
Chao-Chuan Wu*,%, Chi-Tan Hu#,%, Ming-Che Lee※, Yao-Jen Chang*, Siou-Mei Pan#, Jia-Ru Wu&, Shu-Chuan Lin#, Wen-Sheng Wu&,1
*Department of Surgery,
Hepatocellular carcinoma (HCC) ranks sixth in incidence and third in mortality among all cancers worldwide. Metastatic spreads are responsible for poor prognosis of most HCC. The receptor tyrosine kinase of hepatocyte growth factor (HGF), c-Met, is now regarded as one of the promising therapeutic targets for prevention of HCC progression. However, c-Met is positive in only 20% to 48% of human HCC cases. On the other hand, the side effects caused by conventional c-Met inhibitors were frequently observed. It is urgent to search more efficient antagonists with safety warrant for prevention of HCC progression. One promising anti-HCC agent is the medicinal peptide LZ-8 (also known as Lingzhi-8), which is purified from the Chinese herbal drug Ganoderma lucidium. Previously LZ-8 has been found to acquire both immunomodulatory and anticancer capability. Recently, LZ-8 was found to be an effective antagonist for prevention the progression of a lot of patient derived HCC cell lines both in vitro and in vivo. LZ-8 may block c-Met-dependent or c-Met-independent signaling to achieve its anti-HCC effects. Deregulated endosomal signaling of c-Met is recently highlighted to be responsible for c-Met dependent tumor progression. Being a peptide with Lectin like activity, LZ-8 may disturb c-Met endosomal processing by promoting the lysosomal degradation of c-Met, resulting in decreased c-Met signaling. In the future, LZ-8 may be proved as a more efficient and safe anti-HCC agent than the conventional drugs. Journal of Nature and Science, 1(3):e50, 2015.
Hepatocellular carcinoma | Chinese herb | Lingzhi-8 | LZ-8 | c-Met
Targeting HGF-c-Met signaling for progression of Hepatocellular carcinoma
Hepatocellular carcinoma (HCC) ranks sixth in incidence and third in mortality among all cancers worldwide . Recently, sorafenib, one of the multi-kinase inhibitors with anti-proliferative, and pro-apoptotic properties, was found to be the most promising agent for HCC management [2-4]. However, the overall outcomes are far from satisfactory with improvement of overall survival for less than one year . Moreover, the acquired resistance and side effect to sorafenib has drawn attention . Since metastatic spreads are responsible for poor prognosis of most HCC [7, 8], it is not surprising to find the limited response to anti-proliferative drugs such as sorafenib. Thus far, effective target therapy aiming at the molecular pathway leading to tumor metastasis of HCC has not been well established.
Tumor metastasis occurs via complicated processes, including epithelial mesenchymal transition (EMT), migration and invasion of primary tumor, followed by intravasation, extravasation and colonization at the metastatic loci . Within tumor microenvironment the primary tumor may interact with stromal and inflammatory cells leading to the secretion of a lot of metastatic factors including hepatocyte growth factor (HGF) [9-12], epidermal growth factor (EGF), and transforming growth factor-b (TGFb) . Among the metastatic factors HGF, a well-known scatter factor, was highlighted in the progression of cancer  including HCC. The receptor tyrosine kinase (RTK) of HGF, c-Met, is deregulated in HCCs which were closely associated with early HCC recurrence . Patients with high c-Met expressing HCCs usually have shorter 5-year survival after curative resection [15-19]. On the other hand, the effects of HGF on metastatic changes of HCC including EMT, migration and invasion have been established [20-22]. Therefore, HGF-c-Met signaling is now regarded as one of the promising therapeutic targets for prevention of HCC progression [2, 23-25].
now, at least
This review focuses on the preclinical trials regarding the anti-HCC effect of Chinese herbal derived medicinal peptide LZ-8. The proposed mechanisms for LZ-8 to suppress c-Met signaling are also discussed.
Preventive effect of Lingzhi-8 on tumor progression of hepatocellular carcinoma
Currently, many potential Chinese herb-derived anticancer compounds have been explored. For example, Celastrol, extracted from the root of Tripterygiumwilfordii Hook, was found to have anti–prostate cancer properties . Moreover, Platycodin D (PD)  and TDP , isolated from the traditional Chinese herb, Platycodonis radix and Garcinia oblongifolia, respectively, have anticancer potential in HCC. One promising anti-HCC agent is the medicinal peptide LZ-8 (also known as Lingzhi-8), which is purified from the Chinese herbal drug Ganoderma lucidium . In previous studies, LZ-8 was found to be an immunomodulatory adjuvant that enhanced the efficacy of cancer DNA vaccines by activating dendritic cells [33, 34]. More recently, the prominent anticancer capability of LZ-8 was highlighted. LZ-8 may suppress proliferation of breast cancer  and lung cancer [36, 37] and retard cell migration of cervical cancer . LZ-8 may induces endoplasmic reticulum (ER) stress to trigger over-autophagy response leading to cell death of the human gastric cancer cell line SGC-7901 . The molecular mechanisms for the antitumor activity of LZ-8 have been intensively studied. For example, LZ-8 may stabilize p53 and increase the CDK inhibitor p21cip , leading to cell cycle arrest of lung cancer cells. In addition, LZ-8 can repress telomerase activity  in lung adenocarcinoma cells. In regard with intracellular signaling, LZ-8 may suppress the protein kinase C-dependent pathway , involved in cancer progression triggered by HGF-c-Met signaling .
In our recent report , we found LZ-8 may serve as an effective antagonist for prevention of tumor progression of a lot of patient derived HCC cell lines. These cell lines have been characterized for the status of c-Met signaling. As demonstrated in the report, cell migration of both c-Met positive and c-Met negative HCC, HCC372 and HCC329, respectively, can be suppressed by LZ-8. In the animal experiment, LZ-8 suppressed intrahepatic metastasis of HCC329  and another c-Met positive HCC, HCC340 (unpublished result), in SCID mice.
Fig.1 LZ-8 suppress tumor progression of HCC via blockade of c-Met dependent or in dependent signaling. LZ-8 may block c-Met-dependent or EGFR-dependent signaling for suppressing the progression of c-Met- positive and negative HCCs.
The anti-HCC effects of LZ-8 on HCC progression were found to be closely associated with the blockade of critical signal transduction . For the c-Met positive HCC372, LZ-8 suppressed both the expression of c-Met and phosphorylation of c-Met (at Tyr1234), which accompanied the decrease of the downstream ERK signaling and the inhibition of cell migration. On the other hand, to identify the signaling pathway mediating cell migration of the c-Met-negative HCC329, receptor array was used to screen the activities of RTKs that are deregulated in this cell. Among the 49 phosphorylated RTKs (p-RTKs) examined, p-EGFR was found to be the most highly upregulated in HCC329. Importantly, treatment of HCC329 with LZ-8 for 16-24 h specifically decreased p-EGFR by 70%. Consistently, the EGFR inhibitor AG1748 suppress cell migration of HCC329 as effective as LZ-8. In addition, LZ-8 may significantly decreased cell survival of both HCC372 and HCC 329. Taken together, LZ-8 may block c-Met-dependent or c-Met-independent signaling for anti-HCC progression (summarized in Fig.1).
Proposed mechanisms for LZ-8 to block c-Met signaling: implication of the c-Met endocytosis
The underlying mechanisms for LZ-8 to block c-Met signaling are being investigated. Since LZ-8 may decrease both expression and phosphorylation of c-Met, it is probable that LZ-8 can affect the gene transcription of c-Met. However, this was excluded by our recent experiments demonstrating that LZ-8 didn’t decrease the c-Met mRNA level in HCC372 (unpublished result). Therefore, LZ-8 may influence the stability of c-Met on the posttranslational level. Recently, the HGF-triggered c-Met endosomal signaling [for review 45] is highlighted in tumor progression . Increased endocytosis/recycling of c-Met coupled with decreased lysosomal degradation of c-Met were responsible for enhanced activation of the GTPase Rac1, leading to increased cell migration, invasion and metastasis of breast cancer cells . Therefore, modifications in the balance between degradation and recycling of c-Met may be a promising strategy for blocking c-Met signaling. We have found LZ-8 and Con A, a mannose specific Lectin, may prevent HGF-induced tumor progression of the HepG2 via blockade of c-Met endosomal signaling (unpublished result). Interestingly, the major biological activities of LZ-8 resemble the mitogenic Lectin which is capable of inducing cellular aggregate formation [47, 48]. Therefore, it is tempting to speculate that LZ-8 may disturb c-Met endosomal processing in HCC372 by promoting the lysosomal degradation of c-Met and decreased c-Met signaling.
Conclusion and perspective
LZ-8 acquires broad capabilities of suppressing the critical signal pathways, either c-Met- dependent or independent, mediating the progression of diverse HCCs. Being an active component of the Chinese herbal Lingzhi, the safety concern of LZ-8 has been approved. Whether LZ-8 can be a more efficient anti-HCC agent than the conventional drugs is worthy of further clinical investigation.
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Conflict of interest: No conflicts declared.
1Correspondence: Wen-Sheng Wu. Institute
of medical biotechnology,
% Chao-Chuan Wu and Chi-Tan Hu contribute equally to the paper
© 2015 by the Journal of Nature and Science (JNSCI).