Project Grant R21CA288449

ROLES OF GUT-BREAST AXIS IN BREAST PATHOPHYSIOLOGY - MICROBIOME IMPACTS CANCER DEVELOPMENT AND THERAPEUTIC EFFICACY. IN ADDITION TO THE GUTS, MICROBES RESIDE IN DIFFERENT TISSUES INFLUENCING THE PATHOPHYSIOLOGY OF THE TISSUE MICROENVIRONMENT. THESE TISSUE-RESIDENT MICROBES ARE LARGELY ATTRIBUTED TO TRANSLOCATION OF GUT MICROBES. IN THE BREAST, SUCH PASSAGE IS TERMED 'GUT- BREAST AXIS', HELPING ESTABLISH MICROBIOTAS OF BREAST TISSUE AND MILK. NEVERTHELESS, GUT-BREAST AXIS HAS BEEN MOSTLY CONCEPTUALIZED AROUND PREGNANCY, AND IT IS COMPLETELY UNKNOWN WHETHER THIS AXIS INDEED EXISTS OUTSIDE PREGNANCY TO IMPACT BREAST HEALTH AND CARCINOGENESIS. OUR LONG-TERM GOAL IS TO DISSECT HOW MICROBIOME CONTRIBUTES TO BREAST PATHOPHYSIOLOGY. ESPECIALLY, THE OBJECTIVES OF THE PRESENT STUDY ARE TO DETERMINE I) WHETHER GUT-BREAST AXIS OCCURS ON A REGULAR BASIS; II) WHETHER THIS INVOLVES DISCRETE SETS OF BACTERIA FOR HEALTHY COHORTS VS. CANCER PATIENTS, AND III) WHAT ARE THEIR ROLES. OUR CENTRAL HYPOTHESIS IS THAT GUT-BREAST AXIS TAKES PLACE ON A REGULAR BASIS, INVOLVING DISTINCT SETS OF BACTERIA TO CONFER ANTI-TUMOR EFFECTS ON HEALTHY COHORTS VS. PRO-TUMOR EFFECTS ON CANCER PATIENTS. THE PROPOSED RESEARCH IS BASED ON OUR PRELIMINARY STUDIES ALLOWING US TO HARVEST SPECIFIC GUT MICROBIOTAS FROM TUMOR-PROTECTED OR -SUSCEPTIBLE ANIMALS. WE REPORTED THAT SUPPLEMENTING SEPIAPTERIN (SEP)-THE ENDOGENOUS PRECURSOR OF TETRAHYDROBIOPTERIN (THE COFACTOR OF NITRIC OXIDE (NO) SYNTHASE)-NORMALIZED ARGININE METABOLISM AND IMPROVED THE IMMUNOGENICITY OF HER2-POSITIVE MAMMARY TUMORS. WE THEN ORALLY APPLIED SEP TO MICE PRONE TO HER2-POSITIVE MAMMARY TUMORS AND SAW STRONG TUMOR PREVENTION. THESE MICE ALSO SHOWED INCREASES IN NO LEVELS AND NO-PRODUCING BACTERIA IN THE GUTS. BESIDES, EXTRACTS OF THESE GUT BACTERIA ACTIVATED INNATE IMMUNE CELLS, SUGGESTING THE ROLES OF THESE GUT BACTERIA IN ANTI- TUMOR IMMUNITY. HERE, WE WILL DETERMINE WHETHER THESE GUT BACTERIA PHYSICALLY TRANSLOCATE TO THE BREAST TO EXERT TUMOR PREVENTATIVE EFFECTS. OUR HYPOTHESIS WILL BE TESTED THROUGH TWO SPECIFIC AIMS: 1) DETERMINE WHETHER GUT MICROBIOTAS OF A) TUMOR-PROTECTED VS. B) -SUSCEPTIBLE MICE EXERT ANTI-TUMOR VS, PRO-TUMOR EFFECTS; AND 2) DETERMINE WHETHER DISTINCT SETS OF GUT MICROBES ARE TRANSLOCATED TO MAMMARY GLANDS TO EXERT ANTI-TUMOR VS. PRO-TUMOR EFFECTS. IN AIM 1, WE WILL TRANSPLANT GUT MICROBIOTA OF A) TUMOR-PROTECTED (SEP-TREATED) OR B) - SUSCEPTIBLE (DMSO-TREATED) HER2 MICE INTO RECIPIENTS AND GIVE THE INVERSE DRUG TREATMENTS. WE WILL TEST WHETHER THE TRANSPLANTED MICROBIOTAS ANTAGONIZE THE TREATMENTS. IN AIM 2, GUT MICROBIOTA OF A) TUMOR-PROTECTED (SEP) VS B) -SUSCEPTIBLE (DMSO) MICE ARE DIFFERENTIALLY LABELED, AND THE 50:50 MIXTURE IS GIVEN TO THE RECIPIENTS UNDERGOING SEP OR DMSO TREATMENT. LABELED MICROBES ARE ANALYZED FOR THEIR GUT-BREAST TRANSLOCATION; THEIR RATIOS IN THE BREAST; AND THE CONTRIBUTIONS OF BREAST MICROBIOTA TO THE DRUG EFFECTS. THE PROPOSED STUDY IS INNOVATIVE BECAUSE THIS IS THE FIRST TIME TO CORROBORATE GUT-BREAST AXIS AND ITS CONTRIBUTIONS TO BREAST PATHOPHYSIOLOGY. THE STUDY IS SIGNIFICANT BECAUSE IT WILL HAVE A POSITIVE TRANSLATIONAL IMPACT BY JUSTIFYING THE DEVELOPMENT OF A NEW BREAST CANCER TREATMENT OR PREVENTION STRATEGY FOCUSED ON BREAST MICROBIOTA.