The Strange Case of BCG and COVID-19: The Verdict Is Still up in the Air.

COVID-19, caused by a novel coronavirus, SARS-CoV-2, contributes significantly to the morbidity and mortality in humans worldwide. In the absence of specific vaccines or therapeutics available, COVID-19 cases are managed empirically with the passive immunity approach and repurposing of drugs used for other conditions. Recently, a concept that bacilli Calmette-Guerin (BCG) vaccination could confer protection against COVID-19 has emerged. The foundation for this widespread attention came from several recent articles, including the one by Miller et al. submitted to MedRxiv, a pre-print server. The authors of this article suggest that a correlation exists between countries with a prolonged national BCG vaccination program and the morbidity/mortality due to COVID-19. Further, clinical BCG vaccination trials are currently ongoing in the Netherlands, Australia, the UK, and Germany with the hope of reducing mortality due to COVID-19. Although BCG vaccination helps protect children against tuberculosis, experimental studies have shown that BCG can also elicit a non-specific immune response against viral and non-mycobacterial infections. Here, we summarize the pros and cons of BCG vaccination and critically analyze the evidence provided for the protective effect of BCG against COVID-19 and highlight the confounding factors in these studies.

Epigenetic regulator MLL2 shows altered expression in cancer cell lines and tumors from human breast and colon.

BACKGROUND: MLL2, an epigenetic regulator in mammalian cells, mediates histone 3 lysine 4 tri-methylation (H3K4me3) through the formation of a multiprotein complex. MLL2 shares a high degree of structural similarity with MLL, which is frequently disrupted in leukemias via chromosomal translocations. However, this structural similarity is not accompanied by functional equivalence. In light of this difference, and previous reports on involvement of epigenetic regulators in malignancies, we investigated MLL2 expression in established cell lines from breast and colon tissues. We then investigated MLL2 in solid tumors of breast and colon by immunohistochemistry, and evaluated potential associations with established clinicopathologic variables. RESULTS: We examined MLL2 at both transcript and protein levels in established cell lines from breast and colon cancers. Examination of these cell lines showed elevated levels of MLL2. Furthermore, we also identified incomplete proteolytic cleavage of MLL2 in the highly invasive tumor cell lines. To corroborate these results, we studied tumor tissues from patients by immunohistochemistry. Patient samples also revealed increased levels of MLL2 protein in invasive carcinomas of the breast and colon. In breast, cytoplasmic MLL2 was significantly increased in tumor tissues compared to adjacent benign epithelium (p < 0.05), and in colon, both nuclear and cytoplasmic immunostaining was significantly increased in tumor tissues compared to adjacent benign mucosa (p < 0.05). CONCLUSION: Our study indicates that elevated levels of MLL2 in the breast and colon cells are associated with malignancy in these tissues, in contrast to MLL involvement in haematopoietic cancer. In addition, both abnormal cellular localization of MLL2 and incomplete proteolytic processing may be associated with tumor growth/progression in breast and colonic tissues. This involvement of MLL2 in malignancy may be another example of the role of epigenetic regulators in cancer.

Cancer stem cells and markers: new model of tumorigenesis with therapeutic implications.

In an effort to improve our understanding and treatment of cancer, a new model of tumorigenesis is being developed - the cancer stem cell model. Building upon traditional concepts of cancer and stem cells, this model is intended to shed new light on the continuing struggle with treatment challenges such as tumor drug-resistance and recurrence. This review describes the cancer stem cell model with an emphasis on delineating markers that represent a "stemness" phenotype within certain tumor cells. The objective of this delineation is to develop targeted therapies for the selective elimination of cancer stem cells with minimal toxicity to normal stem cells and tissues. However, this specific targeting of cancer stem cells has proved to be a significant challenge due to the similarity of markers expressed by both normal and cancer stem cells. Still, research in the area of cancer biomarkers is steadily progressing.

Bioinformatics data profiling tools: a prelude to metabolic profiling.

The term metabolic profiling is often used to denote the systematic characterization of the unique biochemical trails or fingerprints left behind by cellular processes. Advances in computational biosciences are often invaluable in dealing with the huge amount of raw data generated from the countless biochemical intermediates that flood the cell at any given time. As a prelude to metabolic profiling, it is essential to completely profile and compile all related information about the genetic and proteomic data. Profiling tools in bioinformatics refer to all those software (web based and downloadable) that compile all related information in single user-interfaces. Generally, these interfaces take a query such as a DNA, RNA, or protein sequence or keyword; and search one or more databases for information related to that sequence. Summaries and aggregate results are provided in a single standardized format that would otherwise have required visits to many smaller sites or direct literature searches to compile. In other words they are software portals or gateways that simplify the process of finding information about a query in the large and growing number of bioinformatics databases.

N-7-Alkyl-2'-Deoxyguanosine as surrogate biomarkers for N-nitrosamine exposure in human lung.

N-Nitrosamines are a large group of chemical compounds that are carcinogenic in animals, and probably in humans. These compounds form DNA adducts, namely 7-methyl-deoxyguanosine monophosphate (7-methyl-dGp) and 7-ethyl-deoxyguanosine monophosphate (7-ethyl-dGp). In study, we have used a combined two-step HPLC and (32)P-postlabeling assay to measure these adducts in the lung tissues of 88 autopsy donors. The mean levels for 7-methyl-dGp and 7-ethyl-dGp were 2.1 ± 0.9 (range 0.4 - 5.3) and 0.9 ± 0.5 (range = 0.1-3.0) adducts per 10(7) dGp. Normal distributions of adduct levels were found. The mean ratio for 7-methyl-dGp to 7-ethyl-dGp was 2.8 (S.D. = 2.3), and the levels were highly correlated (R=0.22, P=0.048). However, this was mostly attributed to nonsmokers. Examinations of adduct levels by race revealed no association with either of adducts studied (P=0.3 and P=0.7 for 7-methyl-dGp and 7-ethyl-dGp, respectively), serum cotinine (P=0.4) or ethanol (P=0.7). Overall, there was no association with smoking status, although there was a borderline correlation of the 7-ethyl-dGp adducts (P=0.09) among men, and for 7-methyl-2'-deoxyguanosine (P=0.03) among women. Women smokers showed higher 7-ethyl-dGp levels than men (P=0.03), and African American smokers had more 7-methyl-dGp levels that Caucasians (P=0.08). This study demonstrates that 7-ethyl-dGp adducts are lower than 7-methyl-dgP adducts in both smokers and non-smokers, but that they were only correlated in nonsmokers. Thus, there is a wide interindividual variation in adduct levels, likely due to differences in N-nitrosamine metabolism, which widens at higher levels of exposure. The presence of lower 7-ethyl-dGp levels in human tissues is consistent with experimental animal studies, yet ethylating N-nitrosamines are more potent than those that cause methylation. Although this study is limited by a small number of study subjects, the findings of higher adduct levels in women and African-American smokers are consistent with the reported increased risk and/or incidence of lung cancer in these groups.

gamma-Radiation-induced chromosomal mutagen sensitivity is associated with breast cancer risk in African-American women: caffeine modulates the outcome of mutagen sensitivity assay.

Several different cancer studies have indicated that lymphocyte mutagen sensitivity is a marker of DNA repair deficiency and increased cancer risk. We have used a mutagen sensitivity assay (MSA) measuring gamma-radiation-induced chromosomal aberrations in freshly cultured lymphocytes and assessed breast cancer risk in African-American women. Concurrently, we conducted duplicate cultures in the presence of caffeine, which overrides G(2) arrest in cultured cells, decreases time to DNA repair, and hence increases the aberration rate. In comparison with the non-caffeine-treated cells, we are conceptually segregating the contribution of DNA repair and time for DNA repair as individual susceptibility phenotypes. Blood samples were obtained from 61 cases and 86 controls at Howard University Hospital. Two sets of whole-blood cultures were established and gamma-irradiated (1 Gy) at 67 hours, one of which was treated with caffeine (1 mg/mL). Thereafter, cultures were processed for obtaining metaphase spreads. Fifty metaphases were screened for chromatid breaks. The mean breaks per cell (MBPC) for cases (0.34 +/- 0.15) was significantly greater than for controls (0.24 +/- 0.12; P < 0.0001). Using the 75th percentile value of controls as a cutoff to define mutagen sensitivity, the sensitive individuals had an odds ratio of 4.5 (95% confidence intervals, 2.2-9.1) for breast cancer compared with individuals that were not sensitive. The adjusted odds ratio was 3.3 (95% confidence intervals, 0.147-73.917), which was statistically significant but was limited by the small number of subjects. The results for caffeine co-culture were not predictive of breast cancer (MBPC: cases, 1.6 +/- 0.9 versus controls, 1.5 +/- 0.8; P = 0.8663). Comparing the MBPC for caffeine and non-caffeine cultures, there was a correlation in controls (n = 79; Spearman r = 0.4286; P < 0.0001), but not in cases (n = 58; Spearman r = 0.06609; P = 0.6221). This study indicates that the MSA phenotype is a risk factor for breast cancer in African-American women, with a significant effect observable even in small studies. The use of caffeine did not enhance the predictivity of MSA, but the correlation with non-caffeine cultures in controls indicates that the MSA phenotype is due to both DNA repair and G(2) arrest capacity.

Morphological and growth altering effects of Cisplatin in C. albicans using fluorescence microscopy.

Changes in morphology and growth curve of Candida albicans in response to treatment by Cisplatin has been studied using fluorescence staining with ethidium bromide. Treatment with Cisplatin was found to markedly inhibit hyphae and ovoid growth as revealed by ethidium bromide staining of drug treated cells. These changes were concomitant with inhibitory effects on the growth curve with respect to untreated cells. Presence of Cisplatin not only caused suppression in the limiting values in the growth curve, but also caused a slight left shift in the EC50 values. Some of the ovoid cells undergoing poisoning with cisplatin were found to be unusually enlarged before undergoing their natural fate thus suggesting formation of similar cytotoxic end products with DNA.