Palmatine Attenuates Metastatic Lung Colonization of Triple Negative Breast Cancer Cells

Abstract

Background: Metastatic breast cancer to the lungs is a serious, life-threatening complication that is difficult to cure. Circulating tumor cells play a key role in the metastatic spread of breast cancer to the lungs via the lymphatic or circulatory system. Palmatine is a protoberberine alkaloid, identified as an active component of traditional African herbal preparations. Palmatine has antimetastatic and antiproliferative effects. The inhibitory activity of palmatine on the metastatic colonization of triple negative breast cancer cells in the lungs was investigated in this study. Methods: 4T1 triple breast cancer cells were transplanted synergically to the thoracic duct of the female balb/c mice via the lymphatic system. Palmatine 1, 5 and 10 mg/kg were administered for 28 days. The lungs were analyzed for levels of arterial blood gas, histological damage, immunohistochemical expression of the metastasis-associated protein 1 (MTA1) and tumor suppressor p53 (p53). Results: Administering palmatine 1-10 mg/kg dose dependently improved hypoxemia, ameliorated metastasis associated lung injury; histology score of 3.33 ± 0.33, 1.67 ± 0.33, 1.33 ± 0.33, decreased lung MTA1 (2.19 ± 0.12, 1.83 ± 0.04, 1.84 ± 0.05) and increased p53 expression (1.99 ± 0.06, 2.27 ± 0.12, 2.34 ± 0.12) respectively. Conclusion: Palmatine preserved lung morphology and demonstrated therapeutic potential in aiding the treatment of lung metastasis.

Keywords: MTA1; lung metastasis; p53; palmatine; triple negative breast cancer.

FIGURE 1

Effect of palmatine on Lung metastasis. Data represents mean ± SEM. n = 10, One-way analysis of variance followed by Dunnett’s post hoc test. Lung arterial blood gas: (A) potential of hydrogen (pH), (B) partial oxygen pressure (PaO₂), (C) partial carbon dioxide pressure (PaCO₂), (D) bicarbonate (HCO₃). (A) ns (not significant) vs. Saline treated and Lung metastasis groups (B) ++++p < 0.0001 vs. Saline treated group and ns (not significant), **p = 0.002, ****p < 0.0001 vs. Lung metastasis group (C) ++++p < 0.0001 vs. Saline treated group and *p = 0.025, ****p < 0.0001 vs. Lung metastasis group (D) ++++p < 0.0001 vs. Saline treated group and *p = 0.0127, ****p < 0.0001 vs. Lung metastasis group. Lung acid-base values: (E) base excess (BE) (F) base excess extracellular fluid (BE ecf) (G) anion gap (H) sodium (Na⁺) (I) potassium (K⁺) (J) Chloride (Cl⁻). (E–G) ++++p < 0.0001 vs. Saline treated group and ns (not significant), ****p < 0.0001 vs. Lung metastasis group (H) +++p = 0.0002 vs. Saline treated group and ns (not significant), *p = 0.0112, ****p < 0.0002 vs. Lung metastasis group (I) ++++p < 0.0001 vs. Saline treated group and **p = 0.0016, ****p < 0.0001 vs. Lung metastasis group (J) ns (not significant) vs. Saline treated and Lung metastasis group. Lung immunohistochemistry: (K) lung histology scores (L) lung MTA1 expression (M) lung p53 expression. (K) ++++p < 0.0001 vs. Saline treated groups and ns (not significant), ***p = 0.001, ****p < 0.0001 vs. Lung metastasis group. (L) ++++p < 0.0001 vs. Saline treated groups and ****p < 0.0001 vs. Lung metastasis group. (M) ns (not significant) vs. Saline treated group and ns (not significant), **p = 0.002, ***p = 0.0007, ****p < 0.0001 vs. Lung metastasis group.

FIGURE 2

Representative photomicrographs of the lung H& E sections. (A) Normal saline (B) lung metastasis (C–E) Palmatine 1–10 mg/kg (F) Doxorubicin 5 mg/kg; AL, alveolus; AD, alveolar duct; RB, respiratory bronchiole. Red arrows show metastatic alterations. Scale bar 20 mm ×10, (A–F).

FIGURE 3

Representative photomicrographs of MTA1 expression in IHC sections of the lung tissue: (A) Normal saline (B) Lung metastasis (C–E) Palmatine 1–10 mg/kg (F) Doxorubicin 5 mg/kg. Data were obtained from five fields per slide with seven slides analyzed from each group. Red arrows show immunoreactive areas. Scale bar 20 mm (×10, (A–F).

FIGURE 4

Representative photomicrographs of p53 expression in IHC sections of the lung tissue: (A) Normal saline (B) Lung metastasis (C–E) Palmatine 1–10 mg/kg (F) Doxorubicin 5 mg/kg. Data were obtained from five fields per slide with seven slides analyzed from each group. Red arrows show immunoreactive areas. Scale bar 20 mm (×10, (A–F).