SOX9 has distinct roles in the formation and progression of different non-small cell lung cancer histotypes

The transcription factor SOX9 is a key regulator of multiple developmental processes and is frequently re-expressed in non-small cell lung cancer (NSCLC). Its precise role in the progression of NSCLC histotypes has, however, remained elusive. We show that SOX9 expression relates to poor overall survival and invasive histopathology in human non-mucinous adenocarcinoma and is absent in murine early minimally invasive and low in human in situ adenocarcinoma. Interestingly, despite wide SOX9 expression across advanced NSCLC histotypes, its genetic deletion in the murine Kras^G12D ;Lkb1^fl/fl model selectively disrupted only the growth of papillary NSCLC, without affecting the initiation of precursor lesions or growth of mucinous or squamous tissue. Spatial tissue phenotyping indicated a requirement of SOX9 expression for the progression of surfactant protein C-expressing progenitor cells, which gave rise to papillary tumours. Intriguingly, while SOX9 expression was dispensable for squamous tissue formation, its loss in fact led to enhanced squamous tumour metastasis, which was associated with altered collagen IV deposition in the basement membrane. Our work therefore demonstrates histopathology-selective roles for SOX9 in NSCLC progression, namely as a promoter for papillary adenocarcinoma progression, but an opposing metastasis-suppressing role in squamous histotype tissue. This attests to a pleiotropic SOX9 function, linked to the cell of origin and microenvironmental tissue contexts. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Neuropathological findings in two patients with fatal COVID-19

AIMS

To describe the neuropathological findings in two cases of fatal Coronavirus Disease 2019 (COVID-19) with neurological decline.

METHODS

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection was confirmed in both patients by reverse transcription polymerase chain reaction (RT-PCR) from nasopharyngeal swabs antemortem. Coronial autopsies were performed on both patients and histological sampling of the brain was undertaken with a variety of histochemical and immunohistochemical stains. RNAscope® in situ hybridization (ISH) using the V-nCoV2019-S probe and RT-PCR SARS-CoV-2 ribonucleic acid (RNA) was performed in paraffin-embedded brain tissue sampled from areas of pathology.

RESULTS

Case 1 demonstrated severe multifocal cortical infarction with extensive perivascular calcification and numerous megakaryocytes, consistent with a severe multi-territorial cerebral vascular injury. There was associated cerebral thrombotic microangiopathy. Case 2 demonstrated a brainstem encephalitis centred on the dorsal medulla and a subacute regional infarct involving the cerebellar cortex. In both cases, ISH and RT-PCR for SARS-CoV-2 RNA were negative in tissue sampled from the area of pathology.

CONCLUSIONS

Our case series adds calcifying cerebral cortical infarction with associated megakaryocytes and brainstem encephalitis to the spectrum of neuropathological findings that may contribute to the neurological decompensation seen in some COVID-19 patients. Viral RNA was not detected in post-mortem brain tissue, suggesting that these pathologies may not be a direct consequence of viral neuroinvasion and may represent para-infectious phenomena, relating to the systemic hyperinflammatory and hypercoagulable syndromes that both patients suffered.