# CRYPTIC PROLACTIN RECEPTORS IN MAMMARY TUMOR CELLS

> **NIH NIH R01** · ST. JUDE CHILDREN'S RESEARCH HOSPITAL · 1988 · $87,386

## Abstract

The long-term objective of this research is to understand the role of
prolactin and its receptors in prolactin-dependent mammary tumor growth.
Mammary tumors have a selective advantage in their host because of their
hypersensitivity to prolactin-induced growth.  The mechanisms responsible
for this well-known observation are unknown.  We propose that this
phenomenon is due to disruptions in the normal routes of intracellular
prolactin and prolactin receptor trafficing and in the transcellular
prolactin transport pathway which in normal differentiated mammary cells,
delivers prolactin to milk.  One expression of these defects is our
observation that mammary tumors contain a unique class of intracellular
"cryptic" receptors whose expression at the cells surface is triggered, in
part, by depleting cells of energy.  Using primary cultures of
carcinogen-induced rat mammary tumors and short-term organ cultures of
normal and neoplastic rat mammary tissue, we propose to:  (1) characterize
the subcellular compartments involved in intracellular movement of
prolactin and its receptors in mammary tumors, (2) compare prolactin
processing in tumors with that in normal mammary tissue during
differentiation and determine the relationship of hormone and receptor
compartmentalization and the appearance and loss of cryptic receptors
during differentiation, and (3) explore the mechanism(s) responsible for
unmasking cryptic receptors.

## Key facts

- **NIH application ID:** 3176265
- **Project number:** 5R01CA038190-03
- **Recipient organization:** ST. JUDE CHILDREN'S RESEARCH HOSPITAL
- **SAM.gov UEI:** JL4JHE9SDRR3
- **Principal Investigator:** MARK E COSTLOW
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $87,386
- **Award type:** 5
- **Project period:** 1985-12-01 → 1988-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3176265

## Citation

> US National Institutes of Health, RePORTER application 3176265, CRYPTIC PROLACTIN RECEPTORS IN MAMMARY TUMOR CELLS (5R01CA038190-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3176265. Licensed CC0.

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