Abstract 2875: Metastases arise as new cancers from cells of target organs transformed by cell-free chromatin particles released from dying circulating tumor cells

Background: According to the current paradigm, metastases arise from cells of the primary tumor that have intravasated into circulation and carried to distant organs where they extravasate, grow and form new tumors. However, mechanisms underlying the many steps involved in the metastatic cascade remain unexplained. The landmark study by Dr. Isaiah Fidler established that 99% of tumor cells injected IV into mice die within 24 hours of reaching target sites (Fidler, JNCI, 1970). We hypothesized that circulating tumor cells (CTCs) also die upon reaching target organs and release oncogenic cell-free chromatin (cfCh) particles which integrate into their cellular genomes and transform them to form new tumors which masquerade as metastases.

Animal Ethics: The study was approved by Institutional Animal Ethics Committee.

Experiments and Results: 1) MDA-MB-231 human breast cancer and A375 human malignant melanoma cells were dually labelled in their DNA with BrdU and in their histones with CellLight® Histone 2B GFP and injected IV into mice. Immuno-fluorescence (IF) microscopy of lung tissues excised at 48 hours revealed abundant dually labelled cfCh particles in nuclei of lung cells; 2) Unlabeled MDA-MB-231 and A375 cells were similarly injected, and IF analysis of lung tissues excised at 72 hours revealed 5 - 20 fold increase in all ten hallmarks of cancer defined by Hanahan and Weinberg when compared with un-injected control lung tissues; 3) Mice injected with unlabeled cells were followed for 2-3 months until they developed lung metastasis which were excised and found to contain both mouse and human DNA when examined by highly specific FISH probes. The tumor cells also contained human specific HLA ABC Class I and mouse specific MHC Class II proteins when examined by highly specific mAbs; 4) Metaphase spreads prepared from primary cultures from lung metastasis were found to contain chimeric chromosomes with both mouse and human DNA. The cells expressed both human and mouse specific proteins in the same cells; 5) Several single cell clones developed from primary cultures were also found to contain chimeric chromosomes of mouse and human DNA and to express both mouse and human specific proteins; 6) cfCh particles were isolated from Adriamycin treated dying MDA-MB-231 cells by modification of a method described by us (Mittra et al J Biosciences 2015). When the isolated cfCh particles were injected IV into mice, they went on to develop lung metastasis after ˜ 7 months, thereby directly implicating cfCh in development of metastases. The cfCh induced tumors were again found to contain both mouse and human specific DNA and proteins.

Conclusion: Metastases arise as new cancers from cells of target organs transformed by cfCh particles released from dying CTCs. This conclusion challenges the dogma that metastases arise from cells that are derived from the primary tumor.

Citation Format: Indraneel Mittra, Venkata Raghuram Gorantla, Soniya Shende, Naveen Kumar Khare, Harshada Wani, Ratnam Prasad, Kavita Pal. Metastases arise as new cancers from cells of target organs transformed by cell-free chromatin particles released from dying circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2875.

Variations of the celiac trunk and its branches associated with the shift of vascular hilum (porta hepatis) of the liver

The knowledge of vascular variations, like other anatomical variations, is important during the operative, diagnostic and endovascular procedures in abdomen. This report describes variations in the celiac trunk and abnormal entry of hepatic arteries into the liver as found during routine dissection in approximately 65 years old female cadaver. The celiac trunk was two inches long and gave 2 inferior phrenic arteries, a left gastric artery, and then bifurcated into a splenic and a common hepatic artery. The common hepatic artery gave rise to left hepatic artery, which entered the liver through fissure for ligamentum venosum. The common hepatic artery then divided into right hepatic and gastroduodenal arteries. The cystic artery was a branch of the left hepatic artery. The porta hepatis of the liver was situated on the right side of the caudate lobe.The knowledge of variation reported here is important during endovascular procedures, cholecystectomy and liver transplantation from the living donors (Fig. 2, Ref. 18).

Molecular detection of Mycobacterium tuberculosis in formalin-fixed, paraffin-embedded tissues and biopsies of gastrointestinal specimens using real-time polymerase chain reaction system

BACKGROUND/AIMS

We aimed to perform the molecular detection of Mycobacterium tuberculosis in formalin-fixed, paraffin-embedded tissues and biopsies of gastrointestinal specimens using real-time polymerase chain reaction system.

METHODS

The study included three groups: (A) control (n=24), with no previous signs of M. tuberculosis complex (MTBC), (B) patients (n=28) with known TB origin and (C) patients (n=50) with clinical and histopathological signs of TB but who were culture- and acid-fast bacilli (AFB)-negative. The samples were obtained from the Medical and Surgical Gastroenterology Departments of Bhopal Memorial Hospital and Research Centre. We extracted DNA using DNeasy Blood & Tissue kit (QIAGEN, Germany) and performed realtime assay using Roche LightCycler 2.0 with fluorescence resonance energy transfer (FRET) hybridization probes obtained from Roche Molecular Diagnostics (USA) for the specific amplification of the 159 bp region of the mycobacterium genome.

RESULTS

All the samples (n=24) of Group A were found to be negative, while in Group B, 27 out of the 28 cases studied were found to be positive by LightCycler real-time polymerase chain reaction (LC PCR). In Group C, 18 out of the 50 cases studied were found to be positive, showing a positivity of 36%. The overall positive and negative predictive values of the test for clinical TB (Group C) were 100% and 96.9%, respectively.

CONCLUSIONS

Results of our investigation demonstrated that the real-time detection technology using FRET probes has much higher sensitivity for the detection of MTBC DNA in tissue biopsy samples and formalin-fixed paraffin-embedded surgically resected tissues of the gastrointestinal tract.

Analysis of cellular response to isocyanate using N-succinimidyl N-methylcarbamate exposure in cultured mammalian cells

Isocyanates (R--N==C==O), one of the highly reactive industrial intermediates, possess the capability to modulate the bio-molecules by forming toxic metabolites and adducts which may cause adverse health effects. Some of their toxic degradations have previously been unknown and overlooked; of which, molecular repercussions underlying their genetic hazards upon occupational/accidental exposures still remain as an intricate issue and are hitherto unknown. To assess the genotoxic potential of methyl isocyanate in cultured mammalian cells after in vitro exposure, we performed a study in three different normal cell lines MM55.K (mouse kidney epithelial), B/CMBA.Ov (mouse ovarian epithelial), and NIH/3T3 (primary mouse embryonic fibroblast). Cellular DNA damage response was studied for qualitative phosphorylation states of ATM, gammaH2AX proteins and quantitative state of p53 phosphorylation; DNA cell cycle analysis and measure of cellular apoptotic index before and after treatment were also investigated. Our results demonstrate that methyl isocyanate by negatively regulating the DNA damage response pathway, might promote cell cycle arrest, and apoptosis in cultured mammalian cells suggestive of causing genetic alterations. We anticipate that these data along with other studies reported in the literature would help to design better approaches in risk assessment of occupational and accidental exposure to isocyanates. We also predict that increasing knowledge on DNA damage-triggered signaling leading to cell death could provide new strategies for investigating the effects of DNA repair disorders and decreased repair capacity on the toxicity and carcinogenic properties of environmental toxins.

Anomalous origin of the lumbrical muscles: a study on South Indian cadavers

Although variations in the attachments of the lumbrical muscles have been commonly reported, these have been seen mainly in the Caucasian population. The present study has been undertaken in South Indian population. The upper extremities of 24 South Indian (20 male and four female) cadavers were examined. Three instances of variant origins of the lumbrical muscles (two instances of the second and one of the first lumbrical) were seen. The muscles were unusually long extending to the level of the proximal border of the flexor retinaculum and in two of the cases it was taking origin from the flexor digitorum profundus tendon and its accessory belly. In one case it was taking origin from the flexor digitorum profundus and superficialis tendons. An anomalous origin of the lumbrical from muscles in the forearm has the potential to cause compression of the median nerve in the carpal tunnel.