Breast cancer (BC) is the most common cancer among women. It is known that the prolactin receptor (PRLR) may play a role in breast carcinogenesis, but the available data are often contradictory. To get a more complete picture of the relationship between the receptor and mammary gland carcinogenesis, we examined the association between changes in PRLR expression level and tumor subtype (and its main characteristics). To do this, using real-time PCR, we evaluated the level of PRLR mRNA in BC tissue samples and untransformed adjoining tissue samples (89 pairs). Since the androgen receptor (AR) has begun to be seen as a prognostic marker in breast cancer, we also evaluated the association between mRNA levels of AR and PRLR. We found a significant increase in PRLR expression in luminal subtypes; the highest level of PRLR mRNA was detected in luminal A subtype. In HER2-positive ER-, PR-negative BC, the PRLR mRNA level decreases in tumor tissues compared with untransformed tissues. High PRLR expression is also associated with smaller tumor size in luminal B HER2-negative subtype. In ER-, PR-negative tumors, PRLR expression is associated with AR expression: PRLR mRNA level is increased when AR mRNA level is reduced by more than 8 times in triple-negative tumors; in contrast, in HER2-positive subtype it decreases more significantly when AR expression is reduced by more than 3 times. A tendency towards an increase in PRLR expression with an increase in the AR mRNA level was also discovered in luminal subtypes. The level of PRLR expression depends on the age of patients. In luminal A, PRLR expression is higher in patients under 65 years. In contrast, in luminal B HER2-negative and triple-negative BC, reduced PRLR expression was observed in patients under the age of 40 years and under the age of 50 years, respectively. In this group of patients under the age of 40 years with luminal B HER2-negative BC, ER expression was also reduced (0-4 score according to the IHC assay). Thus, PRLR probably plays a different role in the development and progression of BC: in luminal A and luminal B HER2-positive subtypes PRLR may act as an oncogen, and in luminal B HER2-negative and ER-, PR-negative subtypes can play a tumor suppressor role.Rak molochnoĭ zhelezy (RMZh) iavliaetsia naibolee rasprostranennym onkologicheskim zabolevaniem sredi zhenshchin. Izvestno, chto retseptor prolaktina (PRLR) mozhet igrat' rol' v kantserogeneze molochnoĭ zhelezy cheloveka, no imeiushchiesia dannye zachastuiu protivorechivy. Chtoby poluchit' bolee polnoe predstavlenie o sviazi retseptora s kantserogenezom molochnoĭ zhelezy, my issledovali sviaz' izmeneniĭ v urovniakh ékspressii PRLR s podtipom opukholi i osnovnymi ee kharakteristikami. Dlia étogo s pomoshch'iu PTsR v rezhime real'nogo vremeni my otsenili uroven' mRNK PRLR v tkaniakh RMZh i prilegaiushchikh k opukholi neizmenennykh tkaniakh (89 par). Poskol'ku v poslednee vremia v kachestve markera pri RMZh rassmatrivaetsia androgenovyĭ retseptor (AR), my takzhe otsenili sviaz' mezhdu urovniami mRNK AR i PRLR. My vyiavili dostovernoe uvelichenie ékspressii PRLR v opukholiakh liuminal'nykh podtipov, naibolee vysokiĭ uroven' mRNK PRLR vyiavlen pri liuminal'nom A RMZh. Pri HER2-pozitivnom ER-, PR-negativnom RMZh uroven' mRNK retseptora snizhaetsia v opukholevykh tkaniakh po sravneniiu s neizmenennymi tkaniami. Vysokaia ékspressiia PRLR takzhe assotsiirovana s men'shim razmerom opukholi pri liuminal'nom B HER2-negativnom RMZh. Pri ER-, PR-negativnykh opukholiakh ékspressiia PRLR assotsiirovana s ékspressieĭ AR i uvelichivaetsia pri snizhenii bolee chem v 8 raz urovnia mRNK AR v trizhdy negativnykh opukholiakh, no v protivopolozhnost' étomu v opukholiakh HER2-pozitivnogo podtipa bolee znachitel'no umen'shaetsia pri umen'shenii ékspressii AR bolee chem v 3 raza. Tendentsiia k uvelicheniiu ékspressii PRLR pri uvelichenii urovnia mRNK AR nabliudalas' i pri liuminal'nykh opukholiakh. Takzhe uroven' ékspressii PRLR zavisit ot vozrasta patsientov. Pri liuminal'nom A RMZh bolee vysokaia ékspressiia PRLR kharakterna dlia patsientov v vozraste do 65 let. Naprotiv, pri liuminal'nom B HER2-negativnom i trizhdy negativnom RMZh snizhennyĭ uroven' ékspressii PRLR nabliudalsia u patsientov do 40 let i do 50 let sootvetstvenno. U dannoĭ gruppy patsientov v vozraste mladshe 40 let s liuminal'nym B HER2-negativnym RMZh takzhe byla snizhena ékspressiia ER (0-4 ballov soglasno IGKh issledovaniiu). Takim obrazom, retseptor prolaktina igraet, veroiatno, raznuiu rol' v razvitii i progressii RMZh dannykh podtipov: pri liuminal'nom A i liuminal'nom B HER2-pozitivnom RMZh PRLR, veroiatno, vypolniaet funktsii onkogena, a pri liuminal'nom B HER2-negativnom i ER-, PR-negativnykh opukholiakh mozhet igrat' rol' opukholevogo supressora.