I se how you could cocnlude this, but they are referring to a cancerous cell line, which isn't indicative of normal physiology. Actually, reducing estrogen can increase progesterone, which is a compound that can be used in the synthesis of estrogens, so it's a compensation mechanism to increase estrogen.

This study is referring to ER positive breast cancer, where estrogen is necessary to mediate many of the "cancerous" effects, one of which is upregulation of progesterone receptors. However, this isn't indicative of normal tissue.

maybe Doc M can add more to this.