Arginine deprivation as an anticancer therapy has historically been met with limited success. The development of pegylated arginine deiminase (ADI-PEG20) has renewed interest in arginine deprivation for the treatment of some cancers. The efficacy of ADI-PEG20 is directly correlated with argininosuccinate synthetase (ASS) deficiency. CWR22Rv1 prostate cancer cells do not express ASS, the rate-limiting enzyme in arginine synthesis, and are susceptible to ADI-PEG20 in vitro. Interestingly, apoptosis by 0.3 Mg/mL ADI-PEG20 occurs 96 hours posttreatment and is caspase independent. The effect of ADI-PEG20 in vivo reveals reduced tumor activity by micropositron emission tomography as well as reduced tumor growth as a monotherapy and in combination with docetaxel against CWR22Rv1 mouse xenografts. In addition, we show autophagy is induced by single amino acid depletion by ADI-

Eukaryotic cells can synthesize the non-essential amino acid arginine from aspartate and citrulline using the enzyme argininosuccinate synthetase (ASS). It has been observed that ASS is under-expressed in various types of cancers ASS, for which arginine become auxotrophic. Arginine deiminase (ADI) is a prokaryotic enzyme that metabolizes arginine to citrulline and has been found to inhibit melanoma and hepatoma cancer cells deficient of ASS. We tested the hypothesis that pancreatic cancers have low ASS expression and therefore arginine deprivation by ADI will inhibit cell growth. ASS expression was examined in 47 malignant and 20 non-neoplastic pancreatic tissues as well as a panel of human pancreatic cancer cell lines. Arginine deprivation was achieved by treatment with a recombinant form of ADI formulated with polyethylene glycol (PEG-ADI). Effects on caspase activation, cell growth and cell death were examined. Furthermore, the effect of PEG-ADI on the in vivo growth of pancreatic xenografts was examined. Eighty-seven percent of the tumors lacked ASS expression; 5 of 7 cell lines similarly lacked ASS expression. PEG-ADI specifically inhibited growth of those cell lines lacking ASS. PEG-ADI treatment induced caspase activation and induction of apoptosis. PEG-ADI was well tolerated in mice despite complete elimination of plasma arginine; tumor growth was inhibited by ∼50%. Reduced expression of ASS occurs in pancreatic cancer and predicts sensitivity to arginine deprivation achieved by PEG-ADI treatment. Therefore, these findings suggest that arginine deprivation by ADI could provide a beneficial strategy for the treatment of pancreatic cancer, a malignancy in which new therapy is desperately needed.

No abstract

Background: As more people become vaccinated against the SARS-CoV-2 virus, reports of delayed cutaneous hypersensitivity reactions are beginning to emerge. Methods:In this IRB-approved retrospective case series, biopsy specimens of potential cutaneous adverse reactions from the Pfizer-BioNTech or Moderna mRNA vaccine were identified and reviewed. Clinical information was obtained through the requisition form, referring clinician, or medical chart review.Results: Twelve cases were included. Histopathological features from two injectionsite reactions showed a mixed-cell infiltrate with eosinophils and a spongiotic dermatitis with eosinophils. Three biopsy specimens came from generalized eruptions that showed interface changes consistent with an exanthematous drug reaction. Three biopsy specimens revealed a predominantly spongiotic pattern, consistent with eczematous dermatitis. Small-vessel vascular injury was seen in two specimens, which were diagnosed as urticarial vasculitis and leukocytoclastic vasculitis, respectively. There were two cases of new-onset bullous pemphigoid supported by histopathological examination and direct immunofluorescence studies. Eosinophils were seen in 10 cases. Conclusions:Dermatopathologists should be aware of potential cutaneous adverse reactions to mRNA-based COVID-19 vaccines. Histopathological patterns include mixed-cell infiltrates, epidermal spongiosis, and interface changes.Eosinophils are a common finding but are not always present. Direct immunofluorescence studies may be helpful for immune-mediated cutaneous presentations such as vasculitis or bullous pemphigoid.

Prostate cancer (PCa) cells undergoing neuroendocrine differentiation (NED) are clinically relevant to the development of relapsed castration-resistant PCa. Increasing evidences show that autophagy involves in the development of neuroendocrine (NE) tumors, including PCa. To clarify the effect of autophagy on NED, androgen-sensitive PCa LNCaP cells were examined. Treatment of LNCaP cells with IL-6 resulted in an induction of autophagy. In the absence of androgen, IL-6 caused an even stronger activation of autophagy. Similar result was identified in NED induction. Inhibition of autophagy with chloroquine (CQ) markedly decreased NED. This observation was confirmed by beclin1 and Atg5 silencing experiments. Further supporting the role of autophagy in NED, we found that LC3 was up-regulated in PCa tissue that had relapsed after androgen-deprivation therapy when compared with their primary tumor counterpart. LC3 staining in relapsed PCa tissue showed punctate pattern similar to the staining of chromogranin A (CgA), a marker for NED cells. Moreover, autophagy inhibition induced the apoptosis of IL-6 induced NE differentiated PCa cells. Consistently, inhibition of autophagy by knockdown of beclin1 or Atg5 sensitized NE differentiated LNCaP cells to etoposide, a chemotherapy drug. To identify the mechanisms, phosphorylation of IL-6 downstream targets was analyzed. An increase in phospho-AMPK and a decrease in phospho-mTOR were found, which implies that IL-6 regulates autophagy through the AMPK/mTOR pathway. Most important to this study is the discovery of REST, a neuronal gene-specific transcriptional repressor that is involved in autophagy activation. REST was down-regulated in IL-6 treatment. Knockdown experiments suggest that REST is critical to NED and autophagy activation by IL-6. Together, our studies imply that autophagy is involved in PCa progression and plays a cytoprotective role when NED is induced in PCa cells by IL-6 treatment. These results reveal the potential of targeting autophagy as part of a combined therapeutic regime for NE tumors.

No abstract

Our data reveal distinct clinical and biological differences between NM and SSM that support revisiting the prognostic and predictive impact of primary histology subtype in the management of cutaneous melanoma.

No abstract