High incidence of triple negative breast cancers following pregnancy and an associated gene expression signature

e23170 Background: Centrosome amplification (CA) which refers to presence of supernumerary or abnormally large centrosomes is believed to drive tumor progression by promoting chromosomal instability and the generation of aggressive tumor clones that are more capable of rapid metastasis. Not much is known about factors that drive CA within solid tumors. We have previously shown the existence of rampant CA in triple-negative breast cancers (TNBCs).We report here thatintratumoral hypoxia, which is one of the major contributors to tumor heterogeneity, induces CA in TNBCs via HIF-1α. Methods: We immunohistochemically labeled 24 TNBC and adjacent normal tissue samples for HIF-1α and derived weighted indices (WIs) for nuclear HIF-1α. Adjacent serial sections from the same tumors were immunofluorescently labeled for the centrosomal marker γ-tubulin and CA was determined. Using public microarray datasets (Kao dataset, n = 327), we investigated whether centrosomal gene expression is enriched in breast tumors characterized by a hypoxia gene expression signature. Finally, to test the role of hypoxia in CA induction we exposed cultured TNBC cells (MDA-MB-231 and MDA-MB-468) to hypoxia and overexpressed (OE) or knocked out (KO) HIF-1α and quantitated CA. Results: A strong positive correlation was found between nuclear HIF-1α WI and CA in TNBC samples (Spearman’s rho p = 0.722, p < 0.001), and higher nuclear HIF-1α was associated with worse overall survival (p = 0.041; HR = 1.03). Furthermore, breast tumors with high expression of hypoxia-associated genes exhibited higher expression of centrosomal genes than breast tumors with low expression of hypoxia-associated genes. TNBC cells cultured in hypoxic conditions exhibited ~1.5 fold higher (p < 0.05) CA compared to cells cultured in normoxic conditions. Interestingly, level of CA decreased when HIF-1α KO TNBC cells were exposed to hypoxia; conversely, CA increased when HIF-1α OE TNBC cells were cultured in normoxic conditions. Conclusions: Thus,intratumoral hypoxia drives CA in TNBC via HIF-1α and contributes to poor outcomes. Determination of CA may help identify TNBC patients who could benefit from centrosome declustering drugs and HIF-1α inhibitors.

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Topsentinol L Trisulfate, a Marine Natural Product That Targets Basal-like and Claudin-Low Breast Cancers

Marine Drugs ◽

10.3390/md19010041 ◽

2021 ◽

Vol 19 (1) ◽

pp. 41

Author(s):

Nader N. El-Chaar ◽

Thomas E. Smith ◽

Gajendra Shrestha ◽

Stephen R. Piccolo ◽

Mary Kay Harper ◽

...

Keyword(s):

Breast Cancer ◽

Gene Expression ◽

Cell Lines ◽

Gene Expression Signature ◽

Marine Natural Product ◽

Breast Cancer Cell Lines ◽

Breast Cancers ◽

Expression Signature ◽

Her2 Breast Cancer ◽

Cancer Types

Patients diagnosed with basal-like breast cancer suffer from poor prognosis and limited treatment options. There is an urgent need to identify new targets that can benefit patients with basal-like and claudin-low (BL-CL) breast cancers. We screened fractions from our Marine Invertebrate Compound Library (MICL) to identify compounds that specifically target BL-CL breast cancers. We identified a previously unreported trisulfated sterol, i.e., topsentinol L trisulfate (TLT), which exhibited increased efficacy against BL-CL breast cancers relative to luminal/HER2+ breast cancer. Biochemical investigation of the effects of TLT on BL-CL cell lines revealed its ability to inhibit activation of AMP-activated protein kinase (AMPK) and checkpoint kinase 1 (CHK1) and to promote activation of p38. The importance of targeting AMPK and CHK1 in BL-CL cell lines was validated by treating a panel of breast cancer cell lines with known small molecule inhibitors of AMPK (dorsomorphin) and CHK1 (Ly2603618) and recording the increased effectiveness against BL-CL breast cancers as compared with luminal/HER2+ breast cancer. Finally, we generated a drug response gene-expression signature and projected it against a human tumor panel of 12 different cancer types to identify other cancer types sensitive to the compound. The TLT sensitivity gene-expression signature identified breast and bladder cancer as the most sensitive to TLT, while glioblastoma multiforme was the least sensitive.

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