Metastatic potentials classified with hypoxia-inducible factor 1 downstream genes in pan-cancer cell lines.

Hypoxia-inducible factor 1 (HIF1) is a transcription factor that is stabilized under hypoxia conditions via post-translational modifications. HIF1 regulates tumor malignancy and metastasis by gene transcriptions, such as Warburg effect and angiogenesis-related genes, in cancer cells. However, the HIF1 downstream genes show varied expressional patterns in different cancer types. Herein, we performed the hierarchical clustering based on the HIF1 downstream gene expression patterns using 1406 cancer cell lines crossing 30 types of cancer to understand the relationship between HIF1 downstream genes and the metastatic potential of cancer cell lines. Two types of cancers, including bone and breast cancers, were classified based on HIF1 downstream genes with significantly altered metastatic potentials. Furthermore, different HIF1 downstream gene subsets were extracted to discriminate each subtype for these cancer types. HIF1 downstream subtyping classification will help to understand the novel insight into tumor malignancy and metastasis in each cancer type.

Analysis of the responsiveness to antiandrogens in multiple breast cancer cell lines.

Antiandrogens were originally developed as therapeutic agents for prostate cancer but are also expected to be effective for breast cancer. However, the role of androgen signaling in breast cancer has long been controversial due to the limited number of experimental models. Our study aimed to comprehensively investigate the efficacy of antiandrogens on breast cancer. In the present study, a total of 18 breast cancer cell lines were treated with the agonist or antagonists of the androgen receptor (AR). Among the 18 cell lines tested, only T-47D cells proliferated in an androgen-dependent manner, while the other cell lines were almost irresponsive to AR stimulation. On the other hand, treatment with AR antagonists at relatively high doses suppressed the proliferation of not only T-47D cells but also some other cell lines including AR-low/negative cells. In addition, expression of the full-length AR and constitutively active AR splice variants, AR-V7 and ARV567es, was not correlated with sensitivity to AR antagonists. These data suggest that the antiproliferative effect of AR antagonists is AR-independent in some cases. Consistently, proliferation of AR-knockout BT-549 cells was inhibited by AR antagonists. Identification of biomarkers would be necessary to determine which breast cancer patients will benefit from these drugs.

Identification of a novel RNA transcript TISPL upregulated by stressors that stimulate ATF4.

Cells sense, respond, and adapt to environmental conditions that cause stress. In a previous study using HeLa cells, we isolated reporter cells responding to the endoplasmic reticulum (ER) stress inducers, thapsigargin and tunicamycin, using a highly sensitive promoter trap vector system. Splinkerette PCR and 5' rapid amplification of cDNA ends (5' RACE) identified a novel transcript that is upregulated by ER stress. Its endogenous expression increased approximately 10-fold in response to thapsigargin and tunicamycin within 1 h, but was down-regulated after 4 h. Because the transcript starts from an intron of a long noncoding RNA known as LINC-PINT, we designated the newly identified transcript TISPL (transcript induced by stressors from LINC-PINTlocus). TISPL was also expressed under several other stress conditions. It was particularly increased > 10-fold upon glucose starvation and 7-fold by arsenite exposure. Furthermore, in silico analyses, including a ChIP-atlas search, revealed that there is an ATF4-binding region with a c/ebp-Atf response element (CARE) downstream of the transcription start site of TISPL. Based on these results, we hypothesized that TISPL may be induced by the phospho-eIF2α and ATF4- axis of the integrated stress response pathway, which is known to be activated by the stress conditions listed above. As expected, knockout of ATF4 abolished the stress-induced upregulation of TISPL. Our results indicate that TISPL may be a useful biomarker for detecting stress conditions that activate ATF4. Our highly sensitive trap vector system proved beneficial in discovering new biomarkers.