# The functional loss of the retinoblastoma tumour suppressor is a common event in basal-like and luminal B breast carcinomas

Source: https://onco.cc/key-papers/paper-herschkowitz-rb1-loss-basal-like-bcr-2008/  
OnCo record `paper-herschkowitz-rb1-loss-basal-like-bcr-2008` (Key paper). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Loss of one copy of the RB1 gene was found in 72% of basal-like breast cancers, with low RB1 messenger RNA and high p16, and an RB1-loss expression signature predicted outcome and possibly chemotherapy response.

## Summary

88 primary breast carcinomas and matched normal DNA were subtyped by expression and assessed for RB1 loss of heterozygosity with polymorphic markers. LOH was seen in 39% overall, 72% of basal-like and 62% of luminal B tumours, which also showed low RB1 mRNA; p16INK4a was highly expressed in basal-like tumours consistent with RB1 loss. An RB1-LOH signature was highly prognostic and a potential predictor of neoadjuvant chemotherapy response.

## Fields

- Kind: Key paper
- Last checked: 2026-09-24
- Journal: Breast Cancer Research
- Year: 2008
- DOI: 10.1186/bcr2142
- Authors: Herschkowitz JI, He X, Fan C, Perou CM.
- Findings: RB1 loss of heterozygosity in 72% of basal-like and 62% of luminal B tumours (39% overall).; Low RB1 mRNA and high p16 in basal-like tumours; RB1-loss signature prognostic.
- What it means: Functional RB1 loss is part of basal-like biology, which explains why CDK4/6 inhibitors have not worked in TNBC and why the cell-cycle vulnerability there lies downstream of RB.
- Caveats: 88 tumours; loss of heterozygosity rather than biallelic inactivation.; Later sequencing puts RB1 mutation or deep deletion nearer 15 to 20%.

## Sources

- Herschkowitz et al., Breast Cancer Res 2008: RB1 loss in basal-like and luminal B carcinomas: https://doi.org/10.1186/bcr2142
- PubMed: https://pubmed.ncbi.nlm.nih.gov/18782450/

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- targets: [CDK4/6](https://onco.cc/targets/cdk4-6/), [RB1](https://onco.cc/targets/rb1/)
- pathways: [p53 / RB / cell-cycle checkpoint](https://onco.cc/pathways/p53-cell-cycle/)
- people: [Charles M. Perou](https://onco.cc/people/charles-perou/)
- journals: [Breast cancer research](https://onco.cc/journals/breast-cancer-research/)

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