Response-specific progestin resistance in a newly characterized Ishikawa human endometrial cancer subcell line resulting from long-term exposure to medroxyprogesterone acetate

Abstract

Abstract. Progestins, particularly medroxyprogesterone acetate (MPA), have for a long time been used as conservative treatment for young patients with clinical stage I, grade I endometrial carcinoma. However, more than 30% of patients with endometrial adenocarcinoma display resistance to endocrine therapies at the time of presentation and most cancer patients that initially respond to progestin treatment will at some point develop resistance, resulting in tumor progression. The cellular mechanisms underlying acquired resistance to progestin are poorly understood. In order to investigate the molecular mechanisms whereby human endometrial adenocarcinoma develops resistance to progestin therapy, we have undertaken to develop human endometrial adenocarcinoma cell lines that are resistant to the growth-inhibitory effects of progestins in vitro. A progestin-resistant subcell line of Ishikawa cells was developed from Ishikawa human endometrial adenocarcinoma cells by stepwise selection in increasing concentrations of the synthetic progestin, MPA, over ten months. The doubling time of the progestin-resistant cells (34.18±3.15 h) grown routinely in the medium containing 10 µM MPA was not significantly different from the doubling time of the parent Ishikawa cells (35.14±2.68 h) grown in the absence of MPA (t=-0.331, P=0.762). Moreover, the effect of treatment with MPA shifted from suppression of growth and invasiveness, as observed in the parent Ishikawa cells, to stimulation of growth and invasiveness in the progestin-resistant Ishikawa cells. The positive rates of estrogen receptor a (ERα) and progesterone receptor B (PRB) of the progestin-resistant Ishikawa cells were significantly reduced, whilst the positive rate of ERβ was significantly enhanced compared to the parent Ishikawa cells. These differences were statistically significant (P<0.05). Our results indicate that long-term treatment with MPA in Ishikawa cells may give rise to a resistance effect to MPA. When the resistant subtype is acquired, treatment with MPA enhances cancer cell proliferation and invasiveness. The imbalance of ER and PR subtypes may contribute to the mechanisms involved in progestin resistance. Determination of the subtypes of ER and PR may provide important additional information on the hormone sensitivity of endometrial carcinoma.

Cholesterol Synthetase DHCR24 Induced by Insulin Aggravates Cancer Invasion and Progesterone Resistance in Endometrial Carcinoma

“…DHCR24 is the final enzyme of cholesterol synthesis, and cholesterol is the essential precursor for all steroid hormones, include progesterone1334. It has been reported that constant progestin stimulation gave rise to a resistance effect to progestin and reduced the expression of PGR35. Therefore, we speculate that DHCR24 might display negative feedback on the PGR.…”

Kaempferol Exhibits Progestogenic Effects in Ovariectomized Rats

“…While kaempferol has been described as a partial ER agonist in human breast cancer cells and cervical cells [49,50], multiple studies investigating the estrogenic actions of kaempferol in vivo detected no uterotrophic estrogenic effects [37,60], which is further corroborated in this study. Progestin therapy resistance occurs in some populations of patients with endometrial cancer and endometriosis due to reduced or loss of PR protein expression after prolonged treatment [51,67,68]. Endometrial cancer is the most common gynecological malignancy in the United States and the fifth most common cancer among women in the world [47,53,69].…”

Hsa-circ-0001860 promotes Smad7 to enhance MPA resistance in endometrial cancer via miR-520h

“…However, almost a third of these patients eventually developed MPA resistance 8 . There are several mechanisms that underlie the acquired resistance to MPA, such as PR dysregulation 28 , Immune system and in ammatory response 29 and the activation of lipid metabolism 30 . Recently, some studies show that ncRNAs such as miRNAs and long ncRNAs (lncRNAs) also play vital roles in MPA resistance.…”