Gingerol Reverses the Cancer-Promoting Effect of Capsaicin by Increased TRPV1 Level in a Urethane-Induced Lung Carcinogenic Model

Both gingerol and capsaicin are agonists of TRPV1, which can negatively control tumor progression. This study observed the long-term effects of oral administration of 6-gingerol alone or in combination with capsaicin for 20 weeks in a urethane-induced lung carcinogenic model. We showed that lung carcinoma incidence and multiplicity were 70% and 21.2 ± 3.6, respectively, in the control versus 100% and 35.6 ± 5.2 in the capsaicin group (<i>P</i> < 0.01) and 50% and 10.8 ± 3.1 in the 6-gingerol group (<i>P</i> < 0.01). The combination of 6-gingerol and capsaicin reversed the cancer-promoting effect of capsaicin (carcinoma incidence of 100% versus 20% and multiplicity of 35.6 ± 5.2 versus 4.7 ± 2.3; <i>P</i> < 0.001). The cancer-promoting effect of capsaicin was due to increased epidermal growth-factor receptor (EGFR) level by decreased transient receptor potential vanilloid type-1 (TRPV1) level (<i>P</i> < 0.01) . The capsaicin-decreased EGFR level subsequently reduced levels of nuclear factor-κB (NF-κB) and cyclin D1 that favored enhanced lung epithelial proliferation and epithelial–mesenchymal transition (EMT) during lung carcinogenesis (<i>P</i> < 0.01). In contrast, 6-gingerol promoted TRPV1 level and drastically decreased the levels of EGFR, NF-κB, and cyclin D1 that favored reduced lung epithelial proliferation and EMT (<i>P</i> < 0.01). This study provides valuable information for the long-term consumption of chili-pepper-rich diets to decrease the risk of cancer development

The pharmacological properties of screened three wound healing agents.

<p>(A) Screened three compounds promoted wound closure in a skin excision wound model. (B) Notoginsenoside R1 and aconitine increased blood flow perfusion on laser speckle imaging. (C) Shikonin exerted anti-inflammatory efficacy in the TPA-induced ear edema model. (D) Notoginsenoside R1 and aconitine promoted macrophage phagocytosis of zymosan. The results are presented as mean±SE (n = 10/group). ** <i>p</i> < 0.01, vs. control group.</p

The wound healing microenvironment prevented lung cell malignant transformation.

<p>(A) The combination of three compounds reduced the population expressing stem cell markers or EMT markers examined by flow cytometry and in A549 cells. (B) The combination of three compounds decreased A549 cell self-renew shown as the number of tumor spheres and soft agar colonies. (C) The combination of three compounds decreased the population expressing EMT markers examined by flow cytometry in urethane-treated BEAS-2B cells. The results are presented as mean±SE (n = 5/group) **<i>p</i> < 0.01 <i>vs</i> control group.</p

The combined models increased lung tumor overall volume but did not negatively impact health or significantly affect the body weights of mice.

<p>(A) The combined models increased lung tumor overall volume and decreased carcinogenic preventive efficacy of a single compound. (B-E) The combined models did not negatively impact health or significantly affect the body weights of mice. The results are presented as mean±SE (n = 20/group). **<i>p</i> < 0.01, vs control group.</p

Hypothermia suppressed MNU-mediated cytotoxicity and promoted cell clonogenic capacity.

<p>A. Hypothermia suppressed MNU-induced BEAS-2B cytotoxicity examined by MTT. B and C. Hypothermia decreased MNU-induced BEAS-2B cell apoptosis examined by PI and Annexin V-FITC staining, early apoptosis and late apoptosis were determined as the percentage of Annexin V+/PI- cells and Annexin V+/PI+ cells, respectively. D. Hypothermia promoted MNU-induced BEAS-2B cell clonogenic capacity examined by soft agar assay. Data were expressed as mean ± SD. One asterisk (*)<0.001 as compared to 37°C condition (n = 5).</p

Urethane-induced lung carcinogenesis was associated with lung injury independent of pulmonary inflammation.

<p>(A) Urethane-induced lung carcinogenesis was promoted by BLM- or macrophage depletion-induced lung injury but was not affected by LPS-induced pulmonary inflammation. (B-D) LPS exposure, BLM exposure and macrophage depletion reversed carcinogenic preventive efficacy of single compound but had slight effect on combined efficacy shown as lung tumor incidence, lung tumor number and lung weight, respectively. The results are presented as mean±SE (n = 20/group). *<i>p</i> < 0.05, **<i>p</i> < 0.01, vs control group.</p

The screened three wound healing agents desereased lung tumor overall volume and did not negatively impact health or significantly affect the body weights of mice.

<p>(A) Three wound healing agents desereased lung tumor overall volume. (B-D) Three wound healing agents did not negatively impact health or significantly affect the body weights of mice. The results are presented as mean±SE (n = 10/group). *<i>p</i> < 0.05, **<i>p</i> < 0.01, vs control group.</p

The hypothermia-activated adipocytes promoted lung cancer progression by TGF-β1 and TNF-α.

<p>A. TGF-β1 neutralization relative to MNU alone down-regulated epithelial marker E-cadherin and upregulated mesenchymal markers, such vimentin and fibronectin, and adding TGF-β1 to cells had opposite action in MNU-treated BEAS-2B cells (n = 5). B. TGF-β1 neutralization relative to control promoted CD8+ T cell-mediated cytotoxicity at 37°C and adding TGF-β1 to cells suppressed CD8+ cell-mediated cytotoxicity in A549 cells (n = 5). C. Xenografts of coinjection using A549 cells and 28°C-cultured adipocytes grew rapidly relative to A549 single injection (n = 10). D. A coinjection using either TNF-α or VEGF and A549 cells promoted xenograft development, whereas pre-cultured adipocytes by a TNF-α or VEGF blocking antibody prevented xenograft development relative to A549 single injection (n = 10). Data were expressed as mean ± SD. One asterisk (<b>*</b>)<0.001.</p

Effect of neutralization of TNF-α or TGF-β1 on colony formation and cytotoxicity.

<p>A. Neutralization of TNF-α or TGF-β1 by a blocking antibody reduced MNU-induced clonogenic capacity under 37°C and 28°C condition. B. Neutralization of TNF-α abrogated MNU-induced cytotoxicity but neutralization of TGF-β1 promoted MNU-induced cytotoxicity under 37°C and 28°C condition. Data were expressed as mean ± SD. One asterisk (<b>*</b>)<0.001 as compared to MNU control under the same condition (n = 5).</p

The Combination of Three Natural Compounds Effectively Prevented Lung Carcinogenesis by Optimal Wound Healing

<div><p>The tumor stroma has been described as “normal wound healing gone awry”. We explored whether the restoration of a wound healing-like microenvironment may facilitate tumor healing. Firstly, we screened three natural compounds (shikonin, notoginsenoside R1 and aconitine) from wound healing agents and evaluated the efficacies of wound healing microenvironment for limiting single agent-elicited carcinogenesis and two-stage carcinogenesis. The results showed that three compounds used alone could promote wound healing but had unfavorable efficacy to exert wound healing, and that the combination of three compounds made up treatment disadvantage of a single compound in wound healing and led to optimal wound healing. Although individual treatment with these agents may prevent cancer, they were not effective for the treatment of established tumors. However, combination treatment with these three compounds almost completely prevented urethane-induced lung carcinogenesis and reduced tumor burden. Different from previous studies, we found that urethane-induced lung carcinogenesis was associated with lung injury independent of pulmonary inflammation. LPS-induced pulmonary inflammation did not increase lung carcinogenesis, whereas decreased pulmonary inflammation by macrophage depletion promoted lung carcinogenesis. In addition, urethane damaged wound healing in skin excision wound model, reversed lung carcinogenic efficacy by the combination of three compounds was consistent with skin wound healing. Further, the combination of these three agents reduced the number of lung cancer stem cells (CSCs) by inducing cell differentiation, restoration of gap junction intercellular communication (GJIC) and blockade of the epithelial-to-mesenchymal transition (EMT). Our results suggest that restoration of a wound healing microenvironment represents an effective strategy for cancer prevention.</p></div