Mt1 Melatonin Receptor Prostate Colon Cancer

June 10, 2009 by  
Filed under Prostate Cancer

If you are wondering about the effects of MT1 Melatonin Receptor in prostate or colon cancer, the below will help somewhat.

There have been series of studies carried out by expets to find the effect or not of MT1 Receptor in Prostate, Colon or other types of cancer treatment.

First things first, what is a melatonin receptor? According to Wikipedia, a melatonin receptor is a G protein-coupled receptor (GPCR) which binds melatonin. Among the three types of melatonin receptors that have been cloned are the MT1 (or Mel1A or MTNR1A), MT2 (or Mel1B or MTNR1B) and MT3 (or Mel1C or MTNR1C).

According to, a study carried out by the Department of Physiology, Faculty of Medicine, University of Hong Kong, China…

“Potential involvement of the mt1 receptor in the antiproliferative action of melatonin on androgen-sensitive LNCaP cells, and melatonin-induced modulation of androgen-insensitive PC-3 cell growth, have been reported in vitro. The effects of melatonin on prostate cancer cell proliferation and their association with mt1 receptor expression were investigated in athymic nude mice xenograft models of LNCaP and PC-3 cells.

METHODS: Daily saline or melatonin (4 microg/g body weight) was given to nude mice before or after tumor cell inoculation. Tumor volume was measured periodically, and expression of PCNA, cyclin A, PSA, and mt1 receptor was assessed by immunohisto(cyto)chemistry and/or Western blotting.

RESULTS: Melatonin inhibited the growth of LNCaP tumors, without affecting the growth of PC-3 xenografts, in nude mice. It induced significant decreases in the expression of PCNA, cyclin A, and PSA in LNCaP tumors. Expression of mt1 receptor protein was demonstrated in LNCaP cells, but not in PC-3 cells, both in vivo and in vitro.

CONCLUSIONS: The antiproliferative action of melatonin on LNCaP tumor growth was demonstrated in vivo, and its association with mt1 receptor protein expression suggests the potential involvement of the receptor in the antitumor activity of the pineal gland hormone.”

Other studies that have been carried out on the subject have the following conclusions:

Tam CW, Mo CW, Yao KM, Shiu SY.
Signaling mechanisms of melatonin in antiproliferation of
hormone-refractory 22Rv1 human prostate cancer cells: implications for
prostate cancer chemoprevention.
J Pineal Res. 2007 Mar;42(2):191-202.
PMID: 17286752 [PubMed – indexed for MEDLINE]

“… Taken together with the known molecular mechanisms of
prostate cancer progression and transition to androgen
independence, our data provide strong support for melatonin
to be a promising small-molecule useful for prostate cancer
primary prevention and secondary prevention of the
development and progression of hormone refractoriness.”

Pukkala E, Ojamo M, Rudanko SL, Stevens RG, Verkasalo PK.
Does incidence of breast cancer and prostate cancer decrease with
increasing degree of visual impairment.
Cancer Causes Control. 2006 May;17(4):573-6.
PMID: 16596312 [PubMed – indexed for MEDLINE]
DOI: 10.1007/s10552-005-9005-6

“… CONCLUSIONS: Our findings add to the suggestive
epidemiological evidence for a decreased risk of hormone-
related cancers in people with visual impairment and,
consequently, a relationship between visible light at night
and breast cancer risk. The result is strongly against the
hypothesis of a systemic protective effect related lack of
visible light.”

Sainz RM, Mayo JC, Tan DX, Leon J, Manchester L, Reiter RJ. Melatonin
reduces prostate cancer cell growth leading to neuroendocrine
differentiation via a receptor and PKA independent mechanism.
Prostate. 2005 Apr 1;63(1):29-43.
PMID: 15378522 [PubMed – indexed for MEDLINE]
DOI: 10.1002/pros.20155

(full text PDF file)

“… CONCLUSIONS: The treatment of prostate cancer cells with
pharmacological concentrations of melatonin influences not
only androgen-sensitive but also androgen-insensitive
epithelial prostate cancer cells. Cell differentiation
promoted by melatonin is not mediated by PKA activation
although it increases, in a transitory manner, intracellular
cAMP levels. Melatonin markedly influences the proliferative
status of prostate cancer cells. These effects should be
evaluated thoroughly since melatonin levels are diminished in
aged individuals when prostate cancer typically occurs. …”

Shiu SY, Law IC, Lau KW, Tam PC, Yip AW, Ng WT.
Melatonin slowed the early biochemical progression of
hormone-refractory prostate cancer in a patient whose prostate tumor
tissue expressed MT1 receptor subtype.
J Pineal Res. 2003 Oct;35(3):177-82.
PMID: 12932201 [PubMed – indexed for MEDLINE]

“… This report validates melatonin’s oncostatic action on
prostate cancer and the potential involvement of MT1 receptor
subtype in the attendant antiproliferative signal
transduction as suggested by recent preclinical laboratory
findings in a human.”

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