ST36 EA and antitumour effects

Stimulated by Zhang et al 2021,[1] and Yang et al 2019.[2]

EA – electroacupuncture
IF – impact factor
MDSCs – myeloid-derived suppressor cells
CD8⁺ T cells – cytotoxic T lymphocytes expressing the CD8 glycoprotein
NK cell – natural killer cells (innate lymphoid cells)
4T1 – murine breast cancer cell line (murine = of or affecting mice or related rodents)
luc – luciferase (an enzyme producing bioluminescence)
IL – interleukin
IL1β – inflammatory cytokine
IL-10 – anti-inflammatory cytokine
TNFα – tumour necrosis factor alpha (a potent inflammatory cytokine)
cy7-paclitaxel – cyanine 7 labelled paclitaxel
paclitaxel – chemotherapeutic agent derived from the bark of the Pacific yew tree

key to acronyms

This week we stick with ST36 EA, the vagus and inflammatory cytokines, but rather than pain or RA disease activity, we are focussing on effects in breast tumours.

The first paper was published in the journal Life Sciences (IF 3.53) and comes from a group based in Hangzhou led by Professor Xianghong Jing, who is head of the Institute of Acupuncture and Moxibustion at the China Academy of Chinese Medical Sciences in Beijing. Hangzhou is on the Qiantang river, which opens into the Hangzhou bay to the south of Shanghai and north of Ningbo (previously featured on the blog). It is also the southern terminus of the world’s longest canal system – the Jing–Hang Grand Canal, which is 1104 miles long.

The role of inflammation in tumour initiation and progression was apparently proposed by the German pathologist Rudolf Virchow 140 years ago,[3] so I am a bit slow to this party! That is the first thing I learned from reading this paper’s introduction and checking the references.[1,3,4]

This is a big imposing experimental paper, but the concise introduction lays out the aims and the key outcome targets: MDSCs, CD8⁺ T cells and NK cells. MDSCs increase as a result of excessive inflammation and inhibit the antitumour potential of both CD8⁺ T cells and NK cells. Other outcomes included tumour dimensions, inflammatory mediators, and the effect of vagotomy.

The breast cancer model was generated by injecting 4T1-luc2 cells into a mammary fat pad. 4T1 cells create a tumour very similar to human metastatic triple-negative breast cancer, the disease responsible for the death of my sister in 2012 at the age of 44 (RIP Sara).

As soon as the tumours had grown to a volume of 50mm³, the mice were randomised to receive 30 minutes of EA at ST36 every 2 days from day 10 to day 22, or control, which entailed the same restraint but no needles or EA. Another group of mice were subjected to subdiaphragmatic vagotomy or sham surgery 7 days prior to 4T1-luc2 cell injection and then randomised to EA or control every 2 days from day 10 to day 18. Bioluminescence was measured every 2 days as well, and then tissues were collected at the end of each experiment.

It is stated in the paper that EA was performed at 0.1mA and 2/15Hz with Han’s Point-Nerve Stimulator Instrument (LH202H). I found the details of this device on a blog, and the pulse width appears to vary from 0.2 to 0.6 milliseconds. As far as I can tell, that would be sub-threshold for even the most sensitive nerves, so I am checking that with Professor Jing. In fact, she just contacted me on WeChat, but could not answer as she had started driving home!

Tumour volume and weight were lower in the EA group by around 30%

At day 22, tumour volume and weight were lower in the EA group by around 30%, and the total bioluminescence over the course of the experiment was reduced by around 50%. Inflammatory cytokines IL-1β and TNFα were significantly reduced but did not reach normal levels in control mice with no tumours. The anti-inflammatory cytokine IL-10 did not change significantly. Its role in anti-tumour immunity is controversial. Too little is bad, but so is too much.

It all gets a bit complex now, so I’ll summarise. The good cells (CD8⁺ T cells and NK cells) increased with EA, and the bad cells (MDSCs) decreased.

Vagotomy abolished the inhibitory effects of ST36 EA on tumour growth

Vagotomy abolished the inhibitory effects of ST36 EA on tumour growth, even though neuronal activation in the DMV was noted. This suggests that the efferent vagus nerve is required to mediate the anti-tumour effects of ST36 EA.

I have news from Professor Jing… she must have got home safely through the Beijing traffic! She sent me a picture and a video of the mouse EA. The picture shows a happy looking white mouse with one of its front paws resting on the handle of the needle in ST36. She uses a pair of needles on each side, rather like my favourite combination of ST36 and Zongping. The EA device has a pulse width of 1 millisecond, and the mice tolerate 0.1mA but not 0.2mA when awake and moving freely. Because of the long pulse width (it is 5–10x longer than we use routinely in humans) I estimate that 0.1mA in this experiment is similar to 0.5 to 1.0mA in our terms, so that is certainly strong enough to stimulate some nerves.

The second paper is from 2019,[2] and I first came across it when it was mentioned by a plenary speaker at the WFAS conference where I met Professor Jing. It is a rather similar study in that it used the same murine tumour model and in vivo biofluorescence as one outcome, but the EA was applied local to the tumour (5mm from the tumour border) as a single treatment 20 minutes after injection of cy7-paclitaxel. I cannot find the length of the EA described in either the paper or its supplement, but the frequencies used were a combination of low (3–4Hz) for 5 seconds and intermediate (10–20Hz) for 10 seconds.

EA promoted accumulation of the paclitaxel in the tumour

The main conclusion of this paper is in its title: EA promoted accumulation of the paclitaxel in the tumour by altering the microvasculature. Consequently I assume the rate of apoptosis (cell death) in the tumour was increased, and a variety of other markers suggested improvements.

Both these papers must be considered rather speculative, and there is considerably more basic science research to perform before any transition from the bench to the bedside, but the signs so far seem to provide some hope of antitumour effects of EA, both general (ST36) and local.

References

1          Zhang Z, Yu Q, Zhang X, et al. Electroacupuncture regulates inflammatory cytokines by activating the vagus nerve to enhance antitumor immunity in mice with breast tumors. Life Sci 2021;272:119259. doi:10.1016/j.lfs.2021.119259

2          Yang M, Wan Y, Jiang X, et al. Electro-Acupuncture Promotes Accumulation of Paclitaxel by Altering Tumor Microvasculature and Microenvironment in Breast Cancer of Mice. Front Oncol 2019;9:576. doi:10.3389/fonc.2019.00576

3          Ostrand-Rosenberg S, Sinha P. Myeloid-derived suppressor cells: linking inflammation and cancer. J Immunol 2009;182:4499–506. doi:10.4049/jimmunol.0802740

4          Hanahan D, Weinberg RA. Hallmarks of cancer: the next generation. Cell 2011;144:646–74. doi:10.1016/j.cell.2011.02.013

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Declaration of interests MC