This post was prompted by a side-discussion in a thread initiated by Nalakrats:
"Protocols For Cycling T, or T use in Metastatic Post ADT".
Member "2548oo" mentions Dr John Lee, & is currently using progesterone cream.
I must admit to being wary when I see Dr John Lee's name mentioned in a PCa group. As with Nobel prize winner Otto Warburg, the name is used to justify a range of beliefs & activities.
Let's start with a nice quote from Dr Lee [1]:
"It is well known that the estradiol level in 55-year old men, for example, is usually a bit higher than that of a 55-year old woman. The man, however, does not develop breasts because he has a higher testosterone level than women do. As men age, their estradiol levels gradually rise, whereas their progesterone and testosterone levels gradually fall. The hormone balance changes. These gradual changes lead to reduction in testosterone benefits and eventually to estrogen dominance. That is, his estradiol effects emerge since his testosterone level is not sufficient to block or balance them. Estrogen dominance stimulates breast cell growth and endometrial cell proliferation in women. In men, estrogen dominance stimulates breast cell growth and prostate hypertrophy. Estrogen dominance is responsible for the majority of breast cancers and is the only known cause of endometrial cancer in women. Since the male prostate is the embryonic equivalent of the uterus, is should not be surprising that estrogen dominance is also a major cause of prostate cancer."
(I have no problem with that, although some might.)
Cholesterol is the starting point for steroidogenesis. The first hormone shown in the diagram [2] is pregnenolone, which I have seen referred to as the "grandmother" hormone. Progesterone is produced from pregnenolone.
There are several paths in the steroid cascade that convert pregnenolone [Preg] to testosterone [T], one of which (c) involves progesterone [Prog] directly:
a) Preg --> 17α-hydroxyPreg --> DHEA --> androstenediol --> T
b) Preg --> 17α-hydroxyPreg --> DHEA --> androstenedione --> T
c) Preg --> Prog --> 17α-hydroxyProg --> androstenedione --> T
d) Preg --> 17α-hydroxyPreg --> 17α-hydroxyProg --> androstenedione --> T
Both Preg & Prog are available as supplements in the U.S., as is DHEA. Supplementation is generally intended to correct age-related declines. The argument against usage is that high-level hormones are like pachinko balls in the steroid cascade. You never know where they will end up.
A man on ADT should never add to the four pathways shown above (for obvious reasons - all four increase T).
Zytiga (abiraterone acetate) inhibits 17α-hydroxylase, which takes Preg --> 17α-hydroxyPreg, & Prog --> 17α-hydroxyProg. It also inhibits 17,20-lyase, which takes 17α-hydroxyPreg --> DHEA, & 17α-hydroxyProg --> androstenedione. With all four pathways blocked, progesterone should become irrelevant.
However, since Zytiga is designed to prevent the metabolism of Preg & Prog to androgens, using either wouldn't make sense.
...
Progesterone & Prostate Cancer Cells.
[3] (1982 - U.S. - Johns Hopkins - Patrick Walsh, et al)
"The presence of comparable amounts of progesterone and androgen receptors in human prostatic cytosol deserves further investigation."
[4] (1984 - U.S.)
Interesting study. BPH patients were given Tamoxifen " for 10 days prior to prostate resection". Tamoxifen is a prodrug which is converted to an estrogen receptor antagonist in the body. There were "decreases in progesterone and nuclear androgen receptors" compared to controls. Which "suggest that estrogen has a role in the biological regulation of steroid receptors in the human prostate."
[5] (2001 - Germany)
"The recent discovery of the classical estrogen receptor alpha (ERalpha) in metastatic and recurrent prostatic adenocarcinoma suggests that estrogens are implicated in prostate cancer progression."
"To get more insight into estrogen signaling in prostate cancer tissue, the current study has examined the immunoprofile of the estrogen-inducible progesterone receptor (PR), and evaluated its relation to ERalpha gene expression."
"In primary tumors, the PR was detectable in 36% of primary Gleason grade 3 (5 of 14 cases), 33% of primary Gleason grade 4 (5 of 15 cases), and in 58% of primary Gleason grade 5 tumors (7 of 12 cases). None of the 41 primary tumors investigated revealed significant PR expression in more than 50% of tumor cells. Conversely, moderate to strong receptor expression was observed in 60% of metastatic lesions (9 of 15 cases), and in 54% of androgen-insensitive tumors (38 of 71 cases). Irrespective of grades and stages, the presence of the PR was invariably associated with high steady state levels of ERalpha mRNA, whereas the ERalpha protein was undetectable by immunohistochemistry (IHC) in a significant number of cases (58 of 97 cases)."
"The progressive emergence of the PR during tumor progression obviously reflects the ability of metastatic and androgen-insensitive tumors to use estrogens through a ERalpha-mediated pathway. The present data provide a theoretical background for studying the efficiency of antiestrogens and antigestagens in the medical treatment of advanced prostate cancer."
[6] (2015 - Norway)
"A causal relationship between androgens and the development of prostate cancer is generally considered biologically plausible, but androgens are not the sole effector in the complexity of prostate carcinogenesis. The aim of this study was to evaluate the prognostic significance of progesterone receptor in tumor tissue of T1-3N0 prostate cancer patients undergoing prostatectomy." {535 patients}
"... high tumor cell density ... and high tumor stromal cell density level ... of progesterone receptor were both significantly associated with tumor progression and clinical failure."
"... progesterone receptor expression in tumor cells was an independent negative prognostic factor for clinical failure ..." {Risk factor = 2.5.}"
"High progesterone receptor density in tumor cells of the prostate cancer tumor is an independent negative prognostic factor for clinical failure."
...
Much of the above suggests that progesterone is not to be messed with when PCa exists.
Normally, we have little control over the amount of progesterone the body produces - or of the biological fate of supplemental progesterone. It should be noted, however, that Zytiga, by interfering with its metabolism, potentially increases progesterone levels.
The role of progesterone in the prostate has been under-explored. Progesterone receptors are found in the stroma (PCa occurs in the epithelium). There is crosstalk between stromal & epithelial cells. As PCa develops, changes occur in stromal cells that make the stroma an active participant in progression. One such change is a reduction in progesterone receptors [PR]. This suggests that stromal PR might have a protective role.
But PR in PCa cells is quite another matter, & I see no way that Dr John Lee's old writings can be used to justify the use of progesterone in PCa, given the above. IMO.
-Patrick
[1] johnleemd.com/testosterone-...
[2] en.wikipedia.org/wiki/Stero...
[3] ncbi.nlm.nih.gov/pubmed/618...
[4] ncbi.nlm.nih.gov/pubmed/608...