Two genetic instability pathways viz. chromosomal instability, driven primarily by APC mutation induced deregulated Wnt signaling, and microsatellite instability (MSI) caused by mismatch repair (MMR) inactivation, together account for greater than 90% of late-onset colorectal cancer. Our understanding of early-onset sporadic CRC is however comparatively limited. In addition, most seminal studies have been performed in the western population and analyses of tumorigenesis pathway(s) causing CRC in developing nations have been rare. We performed a comparative analysis of early and late-onset CRC from India with respect to common genetic aberrations including Wnt, KRAS and p53 (constituting the classical CRC progression sequence) in addition to MSI. Our results revealed the absence of Wnt and MSI in a significant proportion of early-onset as against late-onset CRC in India. In addition, KRAS mutation frequency was significantly lower in early-onset CRC indicating that a significant proportion of CRC in India may follow tumorigenesis pathways distinct from the classical CRC progression sequence. Our study has therefore revealed the possible existence of non-canonical tumorigenesis pathways in early-onset CRC in India.

BackgroundSquamous cell carcinoma of tongue (SCCT) is expected to harbor unique clinico-pathological and molecular genetic features since a significant proportion of patients are young and exhibit no association with tobacco or alcohol.MethodsWe determined P53, epidermal growth factor receptor, microsatellite instability, human papilloma virus infection and loss of heterozygosity status at several tumor suppressor loci in one hundred and twenty one oral SCCT (SSCOT) samples and analyzed their association with clinico-pathological features and patient survival.ResultsOur results revealed a significantly higher incidence of p53 nuclear stabilization in early (as against late) onset SCCOT. FHIT loss was significantly associated with p53 nuclear stabilization and the association was stronger in patients with no history of tobacco use. Samples harboring mutation in p53 DNA binding domain or exhibiting p53 nuclear stabilization, were significantly associated with poor survival.ConclusionOur study has therefore identified distinct features in SCCOT tumorigenesis with respect to age and tobacco exposure and revealed possible prognostic utility of p53.

Though primarily a tumor suppressor, TP53 harboring specific missense mutations located in the region encoding the DNA binding domain exhibits a gain of function by transcriptional activation of oncogenes. We performed microarray-based messenger RNA profiling of squamous cell carcinoma of the oral tongue (SCCOT) and identified significant elevation of SMARCD1 in samples exhibiting p53 nuclear stabilization. Activation of SMARCD1 by mutant p53 was confirmed by evaluation of additional tongue cancer samples as well as The Cancer Genome Atlas expression datasets. SMARCD1 knockdown in HNSCC cells resulted in a significant reduction in several tumorigenic characteristics including cell viability, ability to form colonies in liquid and solid media and cell migration. We identified significantly increased SMARCD1 transcript levels in tumor versus matched normal samples in SCCOT as well as in other cancer types. Increased SMARCD1 expression predicted poor survival in HNSCC tumors harboring missense p53 mutations. Our results suggest SMARCD1 to be a novel transcriptional target of mutant p53. K E Y W O R D S gain of oncogenic function, mutant p53, SMARCD1, squamous cell carcinoma of the oral tongue,ZMAT3

NK cells have been shown to display adaptive traits such as memory formation akin to T and B lymphocytes. Here we show that Zika virus infection induces memory like NK cells that express CD27. Strikingly, these cells exhibit stem-like features that include expansion capacity, self-renewal pathway, differentiation into effector cells, longer telomeres and gene signature associated with hematopoietic stem cell (HSC) progenitors. This subset shared transcriptional and epigenetic changes with memory CD8 T cells, stem cells and stem like T cells. These NK cells with memory and stem cell features, which we term “NK memory stem cells”, demonstrated greater antiviral potential than CD27- or naïve CD27+ NK when adoptively transferred to Zika infected mice. Our results also suggest a role for the transcription factor TCF-1 in memory and stemness features of this NK subset. This study defines a unique TCF1hi CD27+ NK subset with memory capacity and stem cell features that play a role in antiviral immunity.