Heparanase cleaves the extracellular matrix by degrading heparan sulfate that ultimately leads to cell invasion and metastasis; a condition that causes high mortality among cancer patients. Many of the anticancer drugs available today are natural products of plant origin, such as hinokitiol. In the previous report, it was revealed that hinokitiol plays an essential role in anti-inflammatory and anti-oxidation processes and promote apoptosis or autophagy resulting to the inhibition of tumor growth and differentiation. Therefore, this study explored the effects of hinokitiol on the cancer-promoting pathway in mouse melanoma (B16F10) and breast (4T1) cancer cells, with emphasis on heparanase expression. We detected whether hinokitiol can elicit anti-metastatic effects on cancer cells via wound healing and Transwell assays. Besides, mice experiment was conducted to observe the impact of hinokitiol in vivo. Our results show that hinokitiol can inhibit the expression of heparanase by reducing the phosphorylation of protein kinase B (Akt) and extracellular regulated protein kinase (ERK). Furthermore, in vitro cell migration assay showed that heparanase downregulation by hinokitiol led to a decrease in metastatic activity which is consistent with the findings in the in vivo experiment.

A polysaccharide isolated from the radix of Astragalus membranaceus, called PG2, used in traditional Chinese medicine, with potential hematopoiesis inducing and immunomodulation activities. PG2 extracted from A. membranaceus has been demonstrated as a novel alternative medicine for cancer patients. Recently, we demonstrated that PG2 enhanced chemotherapy through bystander effect and reduced the expression of indoleamine 2, 3-dioxygenase 1 in tumor cells. Many tumors have been proven to have a high expression of programmed cell death protein ligand-1 (PD-L1), which binds with programmed cell death protein-1(PD-1) in immune cells, thus causing immune tolerance within the tumor microenvironment. With decreased expression of PD-L1, increased immune response can be observed, which might be helpful when developing tumor immunotherapy. The antitumor therapeutic effect mediated by PG2 may associate with an inflammatory immune response at the tumor site. However, the molecular mechanism that by which PG2 inhibits PD-L1 is still incompletely known. The expression of PD-L1 was decreased after tumor cells were treated with PG2. In addition, the cell signaling pathway in tumor cells was evaluated by Western blotting analysis after PG2 treatment. PG2 can downregulate the expression of PD-L1 on the cell surface via the protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/ribosomal protein S6 kinase beta-1 (p70S6K) pathway. In conclusion, our results indicate that PG2 inhibits PD-L1 expression and plays a crucial role in immunotherapy, which might be a promising strategy combined with other treatments.

Marine plants and animals have omega-3 fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA is required for biological processes, but humans are unable to synthesize them and must be obtained from dietary sources. EPA has been used as an antitumor agent but the molecular mechanisms for the regulation of tumor microenvironment immunity by EPA are still unknown. The indoleamine 2,3-dioxygenase 1 (IDO) catalyzes conversion of tryptophan to kynurenine to induce immune evasion in tumor microenvironment. In this study, EPA inhibited the expression of IDO via downregulation of protein kinase B (Akt)/mammalian targets of rapamycin (mTOR) signaling pathway in tumor cells. Meanwhile, a significant decrease in kynurenine levels and increase in T cell survival were observed after tumor cells treated with EPA. The results demonstrated that EPA can activate host antitumor immunity by inhibiting tumor IDO expression. Therefore, our finding suggests that EPA can be enormous potential for cancer immunotherapy.

Melanin is a normal production protecting skin from environment-causing damage. Plants produce some agents in response to their environment. These agents could be applied in cosmetic production. Some Chinese herbals have immunomodulatory activities and modulate the symptoms of several diseases. Melanogenesis represents a complex group of conditions that are thought to be mediated through a complex network of regulatory processes. Previously, some studies found that the extracts of Astragalus membranaceus (PG2) regulated immunity and supported hematopoiesis. Herein, we want to determine the molecular mechanisms by which PG2 inhibits melanogenesis in B16F10 melanoma cells. The cellular melanin contents and expression of melanogenesis-related protein, including microphthalmia associated transcription factor (MITF) and tyrosinase were significantly reduced after PG2 treatment. Moreover, PG2 increased phosphorylation of ERK, without affecting phosphorylation of p38. These results suggested that PG2 as a new target in reducing hyperpigmentation through the ERK signal pathway. PG2 has potential for cosmetic usage in the future.

Chemotherapy is now in common use for the treatment of tumors; however, with tumor growth retardation comes the severe side effects that occur after a chemotherapy cycle. Eicosapentaenoic acids (EPA) used in combination with chemotherapy has an additive effects and provides a rationale for using EPA in tandem with chemotherapy. To improve the efficacy and safety of this combination therapy, a further understanding that EPA modulates with the tumor microenvironment is necessary. Connexin 43 (Cx43) is involved in enhancing chemosensitivity that was suppressed in a tumor microenvironment. We aim to investigate the role of EPA in chemosensitivity in murine melanoma by inducing Cx43 expression. The dose-dependent upregulation of Cx43 expression and gap junction intercellular communication were observed in B16F10 cells after EPA treatment. Furthermore, EPA significantly increased the expression levels of mitogen-activated protein kinases (MAPK) signaling pathways. The EPA-induced Cx43 expression was reduced after MAPK inhibitors. Knockdown Cx43 in B16F10 cells reduced the therapeutic effects of combination therapy (EPA plus 5-Fluorouracil). Our results demonstrate that the treatment of EPA is a tumor induced Cx43 gap junction communication and enhances the combination of EPA and chemotherapeutic effects.