High Salt Diet May Help Prevent Breast Cancer Metastasis to the Lung? 高鹽飲食可能有助於預防乳腺癌向肺轉移

Sunday 05/23/2021 (jkzx.com) — Dr. Yijuan Xu from Jiangnan University and colleagues conducted a study and found high salt intake could prevent breast cancer metastasis to the lung.

The researchers carried out the study in a 4T1 mouse mammary tumor model. They expected that a high salt intake could worse the prognosis or promoted the metastasis of breast cancer to the lung because early study reports suggest that high salt can do more harm than good.

To their surprise, high salt intake actually suppressed the primary tumor growth and retarded the metastasis to the lung. As a result, this high salt diet improved the fitness and the survival rate of the tumor-bearing mice.

With a high salt diet, the tumor bearing mice reduced their food intake, which may render some anti-tumor effect through caloric restriction. Additionally,the proliferation marker ki-67 was reduced and the expression of p53- the tumor suppressor gene was increased.

The researchers explained that the high salt intake can induce hyperosmotic stress which makes breast cancer cells more vulnerable to p53 -dependent anoikis – a programmed cell death.

They suggest that “endogenous salt deposition might act as the first-line defense system against breast cancer progression as well as metastasis.”

The study was published in J Agric Food Chem. 2018 Apr 4;66(13):3386-3392. doi: 10.1021/acs.jafc.7b05923. Epub 2018 Mar 22.

As encouraging as it can be, another research group led by Dr. Ralf Willebrand from University of Hasselt in Belgium published a study report in Front. Immunol., 04 June 2019 | https://doi.org/10.3389/fimmu.2019.01141 to echo the findings by Dr. Xu.

Similarly, Dr. Ralf Willebrand and colleagues conducted their study in two tumor bearing mice and found high salt diet actually inhibited cancer growth. They found that high salt completely blocked myeloid-derived suppressor cells (MDSCs) without which the tumor growth can be inhibited which has been known previously.

In this study, the normal diet contains 0.5% salt, while the high salt diets contained 1% and 4% which were used before the mice received tumor implants.

According to the report, ” Only at concentrations much higher than 40 mM NaCl high salt conditions were toxic to tumor cells as reported for other tested cell types before.”

The impact of high salt on cancer prognosis remain uncertain and more research should be needed before this dietary practice can be recommended to breast cancer or other cancer patients.

It has been known for long that high salt diet can increase risk of gastric cancer stomach cancer and potentially some other cancers. Some researchers theorized that salt allows a temporal formation of hydrogen chloride which is a carcinogenic strong acid. Dr. Qiuyun Liu et al believe that hydrogen chloride is a major factor for cancer metastasis.

A high salt diet is known to render some pro-inflammatory effect and considered a risk factor for cardiovascular disease.

江南大學的徐一娟及其同事進行了一項研究，發現高鹽攝入可以預防乳腺癌向肺轉移。

研究人員在4T1小鼠乳腺腫瘤模型中進行了這項研究。他們期望高鹽攝入會惡化乳腺癌的預後或促進其向肺的轉移，因為早期的研究報告表明，高鹽可能弊大於利。

令他們驚訝的是，高鹽攝入量實際上抑制了原發性腫瘤的生長並阻礙了向肺的轉移。結果，這種高鹽飲食改善了荷瘤小鼠的健康和存活率。

在高鹽飲食下，荷瘤小鼠會減少食物攝入量，這可能通過熱量限製而產生一些抗腫瘤作用。另外，增殖標誌物ki-67減少並且p53-腫瘤抑制基因的表達增加。

研究人員解釋說，高鹽攝入會引起高滲應激，這會使乳腺癌細胞更容易受到p53依賴的神經衰弱（程序性細胞死亡）的影響。

他們建議“內源性鹽沉積可能是抵抗乳腺癌進展和轉移的一線防禦系統。”

該研究發表在《 J Agric Food Chem》上。 2018四月4; 66（13）：3386-3392。 doi：10.1021 / acs.jafc.7b05923。 EPUB 2018年3月22日

令人鼓舞的是，比利時哈瑟爾特大學的拉爾夫·威蘭布蘭德（Ralf Willebrand）博士領導的另一個研究小組在《前沿》上發表了一份研究報告。 Immunol。，2019年6月4日| https://doi.org/10.3389/fimmu.2019.01141以回應徐博士的發現。

同樣，Ralf Willebrand博士及其同事在兩隻荷瘤小鼠中進行了研究，發現高鹽飲食實際上抑制了癌症的生長。 他們發現高鹽完全阻斷了髓樣來源的抑制細胞（MDSC），沒有這種抑製作用，可以抑制腫瘤的生長，這是先前已知的。

在這項研究中，正常飲食含0.5％的鹽，而高鹽飲食含1％和4％的鹽是在小鼠接受腫瘤植入之前使用的。

根據該報告，“如以前其他測試細胞類型所報導的那樣，僅在濃度遠高於40 mM NaCl的高鹽條件下，它才會對腫瘤細胞產生毒性。”

高鹽對癌症預後的影響尚不確定，在將這種飲食習慣推薦給乳腺癌患者之前，還需要進行更多的研究。

長期以來，眾所周知，高鹽飲食會增加患胃癌，和其他潛在癌症的風險。 一些研究人員認為，鹽可以暫時形成氯化氫，而氯化氫是一種致癌的強酸。 劉秋雲博士等人認為氯化氫是癌症轉移的主要因素。