Differential expression patterns of long noncoding RNAs in a pleiomorphic diatom and relation to hyposalinity.

Long non-coding (lnc)RNAs have been shown to have central roles in stress responses, cell identity and developmental processes in multicellular organisms as well as in unicellular fungi. Previous works have shown the occurrence of lncRNAs in diatoms, namely in Phaeodactylum tricornutum, many of which being expressed under specific stress conditions. Interestingly, P. tricornutum is the only known diatom that has a demonstrated morphological plasticity, occurring in three distinct morphotypes: fusiform, triradiate and oval. Although the morphotypes are interchangeable, the fusiform is the dominant one while both the triradiate and the oval forms are less common, the latter often being associated with stress conditions such as low salinity and solid culture media, amongst others. Nonetheless, the molecular basis underpinning morphotype identity in P. tricornutum remains elusive. Using twelve previously published transcriptomic datasets originating from the three morphotypes of P. tricornutum, we sought to investigate the expression patterns of lncRNAs (lincRNAs and NATs) in these distinct morphotypes, using pairwise comparisons, in order to explore the putative involvement of these noncoding molecules in morphotype identity. We found that differentially expressed lncRNAs cluster according to morphotype, indicating that lncRNAs are not randomly expressed, but rather seem to provide a specific (noncoding) transcriptomic signature of the morphotype. We also present evidence to suggest that the major differences in DE genes (both noncoding and coding) between the stress related oval morphotype and the most common fusiform morphotype could be due, to a large extent, to the hyposaline culture conditions rather than to the morphotype itself. However, several lncRNAs associated to each one of the three morphotypes were identified, which could have a potential role in morphotype (or cell) identity in P. tricornutum, similar to what has been found in both animals and plant development.

Differences in plasma microRNA content impair microRNA-based signature for breast cancer diagnosis in cohorts recruited from heterogeneous environmental sites.

Circulating microRNAs are non-invasive biomarkers that can be used for breast cancer diagnosis. However, differences in cancer tissue microRNA expression are observed in populations with different genetic/environmental backgrounds. This work aims at checking if a previously identified diagnostic circulating microRNA signature is efficient in other genetic and environmental contexts, and if a universal circulating signature might be possible. Two populations are used: women recruited in Belgium and Rwanda. Breast cancer patients and healthy controls were recruited in both populations (Belgium: 143 primary breast cancers and 136 healthy controls; Rwanda: 82 primary breast cancers and 73 healthy controls; Ntot = 434), and cohorts with matched age and cancer subtypes were compared. Plasmatic microRNA profiling was performed by RT-qPCR. Random Forest was used to (1) evaluate the performances of the previously described breast cancer diagnostic tool identified in Belgian-recruited cohorts on Rwandan-recruited cohorts and vice versa; (2) define new diagnostic signatures common to both recruitment sites; (3) define new diagnostic signatures efficient in the Rwandan population. None of the circulating microRNA signatures identified is accurate enough to be used as a diagnostic test in both populations. However, accurate circulating microRNA signatures can be found for each specific population, when taken separately.

Prevalence of Histological Characteristics of Breast Cancer in Rwanda in Relation to Age and Tumor Stages.

Breast cancer is a complex disease, and it is the most common cause of morbidity and mortality among women worldwide. In Sub-Saharan Africa, the clinical characteristics and tumor profiles of breast cancer are still unknown. In the present study we aimed to determine breast tumor profiles of the Rwandan patients in relation to age and tumor stages. We compare our findings to related results from other sub-Saharan Africa studies. Data on age at diagnosis, tumor stage, and hormonal profiles of 138 patients diagnosed between January 2015 and December 2018 were retrospectively retrieved from electronic medical records at three referral hospitals in Rwanda. We compared our results to related findings reported in other Sub-Saharan African countries. All statistical analyses were done using SPSS Inc., Chicago, IL, USA, version 20 and R software languages. The mean age at diagnosis was 49.7 years (SD = 13) and ranged from 17 to 86 years. The majority of patients (57.2%) were diagnosed before 50 years of age compared with 42.8% aged > 50 years. Tumor stage III was the commonest accounting for 62% followed by stage II with 24.8%. The distribution of breast tumor subtypes was ER-, PR-, HER2-: 37.7%; ER+, PR+, HER2-: 31.2%; ER-, PR-, HER2+: 14.5%; ER+, PR+, HER2+: 5.1%; and other subtypes represented 11.6%. There was no statistically significant difference in age and tumor stages between the molecular subtypes. Our findings revealed the predominance of hormonal negative tumors among Rwandan patients with breast cancer. Triple negative was found to be the most common breast tumor subtype regardless of age and tumor stage. Larger prospective studies could examine genetics and environmental factors that may play a role in the differences of tumor characteristics in Sub-Saharan populations.