Irradiated Cell-derived Exosomes Enhance Cell Proliferation and Radioresistance via the MAPK/Erk Pathway

BACKGROUND/AIM

Radiation therapy is pivotal in cancer treatment; however, its efficacy is limited by challenges such as tumor recurrence. This study delves into the role of exosomes, which are molecular cargo-bearing vesicles, in influencing cell proliferation, radioresistance, and consequent post-irradiation tumor recurrence. Given the significance of exosomes from irradiated malignancies in diagnostics and therapy, it is vital to delineate their functional dynamics, especially in breast and cervical cancer cell lines, where the impact of irradiation on exosome behavior remains enigmatic.

MATERIALS AND METHODS

Using MDA-MB-231 and HeLa cell lines, exosomes were isolated from the culture supernatant via ultracentrifugation. The bicinchoninic acid assay was used to measure exosome quantities in irradiated and non-irradiated cells. Radiosensitivity was assessed using colony formation assays, while the role of the MAPK/Erk signaling pathway in recipient cell proliferation and radioresistance was probed using western blotting.

RESULTS

Irradiated cells, in both MDA-MB-231 and HeLa lines, produced significantly more exosomes than their non-irradiated counterparts. Co-culturing irradiated cells with exosomes led to increased cell survival post-irradiation and enhanced cell proliferation in both cell lines. Western blotting indicated elevated p-Erk expression in such cells, underscoring the influence of the MAPK/Erk pathway in radioresistance and proliferation.

CONCLUSION

The study establishes a potential nexus between exosome secretion and tumor resurgence following radiotherapy. The spotlight falls on the MAPK/ERK signaling conduit as a key influencer. This new knowledge provides an innovative strategy for counteracting cancer recurrence after radiotherapy, emphasizing the importance of understanding the multifaceted roles of exosomes in this context.

Biological effects of prostaglandin E2-EP4 antagonist (AAT-008) in murine colon cancer in vivo: enhancement of immune response to radiotherapy and potential as a radiosensitizer

Background

Prostaglandin E2 (PGE2) promotes tumor growth and metastasis by acting on a family of four receptors (EP1-4). We investigated the radiosensitizing effects of a newly developed antagonist of PGE2-EP4 (AAT-008) in mouse colon cancer cells in vivo and explored the mechanism using flow cytometry (FCM).

Methods

CT26WT cells grown in Balb/c mice were used. AAT-008 at doses of 0, 3, 10, and 30 mg/kg/day was orally administered once or twice daily for up to 19 days. On day 3, the tumors were irradiated at 9 Gy in the radiotherapy (RT) group. Tumor sizes were measured every other day. For the first FCM series, AAT-008 (10 mg/kg/day) was administered from day 0 to 18 and RT (9 Gy) was given on day 3. The population of effector T cells (Teff), defined as CD45⁺CD8⁺CD69⁺, in the tumors was investigated on day 19. For the second FCM series, AAT-008 (30 mg/kg/day) was administered from day 0 to 12. The populations of Teff and regulatory T cells (Treg), and the ratio of Teff/Treg were investigated on day 13.

Results

The growth delay effect of AAT-008 administered alone (3-30 mg/kg/day) appeared minimal. In the first growth delay experiment where AAT-008 was administered once daily, the combined effect of AAT-008 (30 mg/kg/day) and RT appeared additive. In the second growth delay experiment where AAT-008 was administered twice daily, the combined effect appeared additive at 3 and 10 mg/kg/day and supra-additive at 30 mg/kg/day. In the first FCM series, the mean Teff proportions in the tumors were 43% and 31% in the 10 mg + RT and 0 mg + RT groups, respectively. Notably, 67% Teff was observed in responsive mice in the 10 mg + RT group. In the second FCM series, the mean Treg proportion and Teff/Treg ratio in the 0 mg + RT and 30 mg + RT groups were 4.0% and 1.5%, respectively (P=0.04) and 10 and 22, respectively (P=0.04).

Conclusions

AAT-008 potentially enhances the radiosensitivity of colon cancer cells, apparently by stimulating the immune system against the cancer cells.

Radiation therapy enhances systemic antitumor efficacy in PD-L1 therapy regardless of sequence of radiation in murine osteosarcoma

Recent studies demonstrate that immune checkpoint blockade (ICB) increases the chances of the abscopal effect, an anti-tumor effect outside the radiation field in radiation therapy. However, the optimal sequence between radiation and ICB remains unclear. To investigate the impact of sequence of radiation in anti-PD-L1 antibody (P1) therapy on immune microenvironments and antitumor efficacies in local and abscopal tumors, metastatic LM8 osteosarcoma cells were inoculated into both legs of C3H mice. For irradiation, only one side leg was irradiated at 10 Gy. Then mice were divided into four groups: administrated anti-PD-L1 antibody three times (P1 monotherapy), receiving radiation 3 days prior to P1 therapy (P1+pre-Rad), and receiving concurrent radiation with P1 therapy (P1+conc-Rad). Thereafter, tumor immune microenvironment and tumor volume changes were analyzed in irradiated and unirradiated tumors. The P1+pre-Rad regimen increased the proportion of CD8+ programmed cell death 1 (PD-1)+ granzyme B (GzmB)+ reinvigorated T cells and decreased the proportion of CD8+ PD-1+ GzmB- exhausted T cells than P1+conc-Rad regimen in unirradiated tumors. Combination regimens suppressed tumor growth in irradiated tumors compared with that in P1 monotherapy. In both irradiated and unirradiated tumors, significant tumor growth suppression and prolonged overall survival were observed under both combination treatment regimens compared with P1 monotherapy. However, no distinct differences in unirradiated tumor volume and survival were observed between P1+pre-Rad and P1+conc-Rad groups. These results suggest that local irradiation is necessary to improve systemic treatment efficacy in P1 therapy regardless of sequence of local irradiation.

High Dose Local Photon Irradiation Is Crucial in Anti-CTLA-4 Antibody Therapy to Enhance the Abscopal Response in a Murine Pancreatic Carcinoma Model

Pancreatic cancer is an extremely treatment-resistant neoplasm to chemotherapy and immunotherapy. The combination of photon beam irradiation and anti-CTLA-4 antibody (C4) for the anti-tumor effect enhancement at local and distant tumors (abscopal tumors) was investigated using the pancreatic ductal adenocarcinoma (PDAC) mouse model. Pan02 cells were bilaterally inoculated to both legs of C57BL/6 mice. High dose photon beams in a hypofractionation or a single fraction were delivered to the tumors on one leg. Monotherapy with C4 via i.p. was not effective for PDAC. The high dose irradiation to the local tumors produced significant shrinkage of irradiated tumors but did not induce the abscopal responses. In contrast, the combination therapy of high dose photon beam irradiation in both hypofractionation and a single fraction with C4 enhanced the anti-tumor effect for abscopal tumors with significantly prolonged overall survival. The flow cytometric analysis revealed that the combination therapy dramatically decreased the regulatory T cell (Treg) proportion while increasing the cytotoxic T lymphocytes in both local and abscopal tumors. These results suggest that high dose photon beam irradiation plays an important role in C4 therapy to enhance the abscopal response with immune microenvironment changes in PDAC, regardless of the fractionation in radiation therapy.

Radiation Dose Escalation is Crucial in Anti-CTLA-4 Antibody Therapy to Enhance Local and Distant Antitumor Effect in Murine Osteosarcoma

We previously reported that a combination of 10 Gy of X-ray irradiation and dual immune checkpoint blockade with anti-CTLA-4 (C4) and anti-PD-L1 antibodies produced a significant shrinkage of irradiated and unirradiated tumors (abscopal effect) and prolonged overall survival. However, the optimal radiation delivery regimen combined with single immune checkpoint blockade of C4 for inducing a maximum systemic antitumor response still remains unclear, particularly for patients with osteosarcoma. We used syngeneic C3H mice that were subcutaneously injected with LM8 osteosarcoma cells into both legs. C4 was administered three times, and one side of the tumor was irradiated by X-ray beams. The optimal radiation dose required to induce the abscopal effect was explored with a focus on the induction of the type-I interferon pathway. Radiation delivered in a single fraction of 10 Gy, 4.5 Gy × 3 fractions (fx), and 2 Gy × 8 fx with C4 failed to produce significant inhibition of unirradiated tumor growth compared with monotherapy with C4. Dose escalation to 16 Gy in a single fraction, or the equivalent hypofractionated dose of 8 Gy × 3 fx, which significantly increased secretion of IFN-β in vitro, produced a dramatic regression of both irradiated and unirradiated tumors and prolonged overall survival in combination with C4. Furthermore, irradiation at 16 Gy in both a single fraction and 8 Gy × 3 fx diminished regulatory T cells in the unirradiated tumor microenvironment. These results suggest that total dose escalation of radiation is crucial in C4 therapy to enhance the antitumor response in both local and distant tumors and prolonged overall survival regardless of fractionation for osteosarcoma.

Variations in the gonadal artery with a single common trunk: embryological hypotheses by observation

BACKGROUND

A gonadal artery originates as a branch of the abdominal aorta and renal artery inferior to the level of origin of the renal arteries. Variations in multiple right testicular arteries (RTAs) arising from the abdominal aorta are common. We aimed to re-evaluate the unusual courses of gonadal arteries with a single common trunk in relation to the inferior vena cava and left renal vein and explain the developmental anatomy.

MATERIALS AND METHODS

The observational cross-sectional study was performed on 54 Japanese adult cadavers (29 men and 25 women). We examined the literature and developed embryological hypotheses on the single common trunk of the gonadal artery.

RESULTS

The gonadal artery, testicular artery, and ovarian artery arose from the abdominal aorta in 93.1%, 96.3%, and 89.6% of cases, respectively, and from the renal artery in 4.9%, 3.7%, and 6.3% of cases, respectively. We found two rare variations in the RTAs observed during the routine dissection of two male cadavers; in these two cases, a single common trunk of the RTAs originated from the abdominal aorta. A single common trunk was found in 3.7% of cadavers, 2.0% of sides, and 2.0% of arteries in the gonadal artery and in 6.9% of cadavers, 3.8% of sides, and 3.7% of arteries in the testicular artery. All cases of the single common trunk, including those in past reports, were observed only in men.

CONCLUSIONS

Knowledge of the variations in RTAs has important clinical consequences for invasive and non-invasive arterial procedures. In addition, this variation provides a new interpretation of the embryology of the gonadal artery. Variations similar to our findings have not been previously reported. Therefore, different variations concerning the RTA should be considered during surgical and non-surgical evaluations.

Argon plasma coagulation for successful treatment of early gastric cancer with intramucosal invasion

BACKGROUND

In recent years, there has been an increasing number of cases of early gastric cancer (T1, NX) with intramucosal invasion, which are untreatable by surgical or endoscopic mucosal resection (EMR) because of their high risk. Currently, no adequate treatment is available for such patients.

AIM

The main objective of this study was to evaluate whether argon plasma coagulation (APC) is an effective and safe modality for treating early gastric cancer untreatable by surgical resection or EMR.

METHODS

The study group comprised 20 men and seven women diagnosed with gastric cancer with intramucosal invasion who were considered poor candidates for surgical resection or EMR due to risk factors such as severe cardiac failure or thrombocytopenia. Irradiation conditions for APC treatment were determined using swine gastric mucosa. We used an argon gas flow of 2 l/min at a power setting of 60 W and a maximum irradiation time of 15 s/cm(2). The follow up period of the 27 patients ranged from 18 to 49 months (median 30 months).

RESULTS

All lesions were irradiated easily, including areas anatomically difficult for EMR such as the gastric cardia or the posterior wall of the upper gastric body. In 26 of 27 patients (96%) there was no evidence of recurrence during the follow up period (median 30 months). One patient showed recurrence six months after the treatment but was successfully retreated. No serious complications were found in any of the 27 patients but three patients (11%) experienced a feeling of abdominal fullness.

INTERPRETATION

APC is a safe and effective modality for treatment of early gastric cancer with intramucosal invasion untreatable by surgical resection or EMR. However, further observations are necessary to determine the long term prognosis of patients undergoing this treatment.

[Study on the characterizations of genus Curcuma plants on the strains of C. longa L. and C. aromatica Salisb preserved at Izu station of NIHS]

To clarify the characteristics of genus Curcuma plants, we studied the properties of six strains of Curcuma longa L. and two strains of C. aromatica Salisb. preserved at Izu Experimental Station for Medicinal Plants of National Institute of Health Sciences. Six strains of C. longa were classified into three types according to morphological characteristics, rhizome production, and differences in curcuminoid content of rhizome. The curcuminoid content of the rhizomes in each strain ranged from 2.20 mg/g to 55.23 mg/g. Strains showing a high curcuminoid content had a low rhizome yield. No difference was observed between two strains of C. aromatica in terms of morphological characteristics. C. longa can be easily distinguished by differences in the development of tuberous roots and the color of the rhizome cross section.

Malignant fibrous histiocytoma of the heart: case report and review of 46 cases in the literature

A rare case of cardiac malignant fibrous histiocytoma (MFH) is reported. A 55-year-old woman complained of palpitation due to atrial fibrillation. Echocardiography, magnetic resonance imaging, and angiography demonstrated a tumor arising from the posterior wall of the left atrium. At surgery, the tumor was almost entirely resected and histologically defined as MFH. Neither chemotherapy nor irradiation was administered. Echocardiography revealed a local recurrence two months after the surgery and the patient died of advanced cachexy and heart failure 2 years later. The details of this case are presented with a review of the literature.

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 10). Testicular toxicity of adriamycin observed 2 and 4 weeks after a single intravenous administration

The present study was performed to clarify whether toxic effects of the antitumor drug, adriamycin (ADR) on the male genital organ can be adequately detected 2 and 4 weeks after a single intravenous administration in the rat. ADR was intravenously administered once to 10 Crj:CD (SD) male rats/group aged 6 weeks (4-week group) and 8 weeks (2-week group) at doses of 0, 2 and 6 mg/kg. The rats were sacrificed at the age of 10 weeks. For comparison 10 rats/group were killed 2 weeks after a single intravenous administration at the age of 4 weeks (immature group). Saline was administered to control rats. Histopathological examination and a quantitative morphometry were carried out after measurement of testes weights at necropsy. In rats of the 4-week and 2-week groups, mean absolute testicular weight in all groups was significantly decreased. However, changes in mean relative weight were not evident in the 2-week group. Disappearance of seminiferous epithelial cells was observed histopathologically in rats dosed with 2 and 6 mg/kg in the 2-week group. The change was more severe in the 4-week group, when reduction of spermatogenesis and giant cells were also observed at 6 mg/kg. The quantitative morphometry in the 2-week group showed decreases in the numbers of spermatogonia and spermatocytes in stages X and XII at 2 mg/kg, and in the numbers of spermatogonia in all stages and spermatocytes in all stages except stage V at 6 mg/kg. Moreover, the numbers of spermatogonia and spermatocytes in all stages and spermatids in stages II-III and V were decreased with dose related manner in the 4-week group. In contrast, no obvious change in testes weights was apparent in the immature group. However, the numbers of spermatogonia and spermatocytes in all stages were decreased at 6 mg/kg. In conclusion, testicular toxicity of ADR could be detected 2 weeks after a single administration. Susceptibility of the testes of immature rats to ADR might be less than that of older animals.

[Geobotanical studies on the island of Tanegashima (affinity of world property island Yakushima)]

A list was drawn up of wild plants growing on Tanegashiama island that were identified in our field work, and the list was compared with the flora of the rest of Japan and the flora of Taiwan. There were 166 families and 1,218 species consisting of 23 families and 159 species of Pteridophyta, 4 families and 7 species of Gymnosperma, 113 families and 700 species of the dicotyledous Angiosperma, and 26 families and 353 species of monocotyledous Angiosperma. There are 229 families and 5,500 species of plants in Japan, 196 families and 3,019 species in Kyushu, and 228 families and 3,477 species in Taiwan. There are 11 species of endemic plants on Tanegashima and Yakushima, and the best known of them is Pinus armandii Francht. var. amamiana Hatsushima. There are 181 species of flora of flora limited to the northern element, including several important medicinal plants, such as Akebia quinata Decaisne and Zanthoxylum piperitum DC. The 69 species of flora limited to the southern element include several important tropical plants, such as Messerschmidia argentea Johnston and Clerodendrum inerme Gaertn. Most of these plants are distributed on both island, but some of are distributed only Tanegashima. We concluded that one of the temperate borderlines of Japanese flora in the temperate zone is the islands of Tokara. The flora of Tanegashima and Yakushima are having a closely affinity of plant species and having the rich plant species.

Systemic lupus erythematosus with a giant rectal ulcer and perforation

A 41-year-old man with systemic lupus erythematosus (SLE) who developed pelvic inflammation due to perforation of a giant rectal ulcer is described. The patient presented with persistent diarrhea, abdominal pain and fever without development of disease activity of SLE. Endoscopic and radiological examinations revealed a perforated giant ulcer on the posterior wall at the rectum below the peritoneal evagination. The ulcerated area was decreased after a colostomy was performed at the transverse colon to preserve anal function. The patient is currently being monitored on an outpatient basis. It should be noted that life-threatening complications such as perforated ulcer of the intestinal tract could occur without SLE disease activity.

Aberrant crypt foci of the colon as precursors of adenoma and cancer

BACKGROUND

Aberrant crypt foci of the colon are possible precursors of adenoma and cancer, but these lesions have been studied mainly in surgical specimens from patients who already had colon cancer.

METHODS

Using magnifying endoscopy, we studied the prevalence, number, size, and dysplastic features of aberrant crypt foci and their distribution according to age in 171 normal subjects, 131 patients with adenoma, and 48 patients with colorectal cancer. We also prospectively examined the prevalence of aberrant crypt foci in 11 subjects (4 normal subjects, 6 with adenoma, and 1 with cancer) before and after the administration of 100 mg of sulindac three times a day for 8 to 12 months and compared the results with those in 9 untreated subjects (4 normal subjects and 5 with adenoma). All 20 subjects had aberrant crypt foci at base line.

RESULTS

We identified 3155 aberrant crypt foci, 161 of which were dysplastic; the prevalence and number increased with age. There were significant (P<0.001) correlations between the number of aberrant crypt foci, the presence of dysplastic foci, the size of the foci, and the number of adenomas. After sulindac therapy, the number of foci decreased, disappearing in 7 of 11 subjects. In the untreated control group, the number of foci was unchanged in eight subjects and slightly increased in one (P<0.001 for the difference between the groups).

CONCLUSIONS

Aberrant crypt foci, particularly those that are large and have dysplastic features, may be precursors of adenoma and cancer.

[Aberrant crypt foci as biomarkers in chemoprevention for colorectal cancer]

Aberrant crypt foci (ACF) are small lesions identifiable in whole-mount preparations of normal-appearing human colonic mucosa with the aid of methyleneblue staining under stereoscopic microscope. Highly frequent mutations of K-ras genes were found, and increased proliferative activities were also observed. Therefore, K-ras gene mutation may have some role in formation of ACF. Using rat experimental model, formation of ACF was shown to be enhanced by cancer promoters (such as secondary bile acids), and to be suppressed by chemopreventive agents (deoxycholic acid and aspirin). Based on these findings, ACF are considered to be precursors of colon cancer. We demonstrated that ACF are the precursors of adenoma-carcinoma sequence. Moreover, we showed that ACF may be suitable biomarkers of chemopreventive agents for colon cancers.

Analysis of CA repeats in first intron of class I ADH gene in Long-Evans Cinnamon rats developing fatal intoxication after ethanol intake

The Long-Evans Cinnamon (LEC) rat is a mutant strain established from Long-Evans rats that displays spontaneous hepatitis and liver cancer. We previously demonstrated that LEC rats died of acute ethanol intoxication after being fed a liquid diet containing 5% ethanol. Furthermore, we found that both alcohol dehydrogenase (ADH) and aldehyde dehydrogenase activities were remarkably suppressed in the liver of LEC rat, compared with Wistar rats. In the present study, we further investigated ethanol metabolism in the non-ADH pathway and what caused the decrease of liver ADH activity in LEC rats. Blood ethanol concentration 5 hr after intraperitoneal administration of ethanol in LEC rats was higher than in the Wistar rats, indicating that ethanol oxidation was impaired in LEC rats. The expression of liver cytochrome P-450IIE1 in the LEC rat was as much as that in Wistar rats. Regarding decreased ADH activity in the liver of LEC rats, we examined an alternating purine-pyrimidine (CA) repeat-length polymorphism in the first intron of a class I ADH gene that would play a role in altering ADH activity. A polymerase chain reaction method was used to amplify the CA repeat in the first intron of this class I ADH gene, a nine CA repeat insertion and a point mutation were detected in LEC rats. These results suggest that this alternating sequence would modify transcription of the class I ADH gene in LEC rats. Thus, LEC rats have abnormal ethanol metabolism in the ADH pathway.

Detection of activity in the conditioned medium of ethanol-treated HepG2 cells which stimulates collagen synthesis in IMR-90 cells

Hepatic fibrosis often occurs in alcoholic liver diseases without accompanying tissue necrosis or inflammation. However, the precise mechanism of this fibrosis has not been fully clarified. In the present study, using the hepatoblastoma cell line HepG2 as a model for hepatocytes, we identified a factor that stimulates collagen synthesis of fibroblasts in a conditioned medium of HepG2 cells after treatment with ethanol. Type 1 procollagen peptide (PIC) in a culture of human fibroblast IMR-90 markedly increased after incubation with the conditioned medium of ethanol-treated HepG2 cells. The stimulating activity on the production of PIC by IMR-90 remained after the dialysis and evaporation of the conditioned medium of HepG2 cells, indicating this factor was not as volatile from low molecular substances such as acetaldehyde, acetate, or lactate. The activity of this factor diminished with heat or trypsin treatment. A gel chromatographic analysis disclosed that the molecular weight of this factor was approximately 8000 Da. These results suggest that a polypeptide factor secreted from HepG2 cells by treatment with ethanol stimulates collagen synthesis of fibroblasts.

Autoantibody against a 78 kDa membrane protein of HepG2 cell in the sera of patients with alcoholic liver diseases

Sera from 14 normal control subjects, 30 patients with alcoholic liver diseases (fatty liver, n = 8; hepatitis, n = 13; liver cirrhosis, n = 9), 7 controls with chronic hepatitis B, and 8 controls with chronic hepatitis C were masured for their concentrations of antibodies against HepG2 membrane protein by a binding assay utilizing 125I-labeled protein A. When the cut-off level was set as the mean value plus 2 SD of normal control subjects, the incidence of positivity was 75%, 69.2%, and 77.8% in patients with alcoholic fatty liver, alcoholic hepatitis, and alcoholic cirrhosis, respectively. Both the mean serum antibody values and the positive incidence were significantly higher in patients with alcoholic liver diseases than in either the normal controls or in the control patients with chronic hepatitis. Sodium dodecylsulfate polyacrylamide gel electrophoresis of 125I-labeled HepG2 membrane protein precipitated with IgG from patients with alcoholic liver diseases revealed an immunoreactive band at a molecular weight of 78,000 daltons (gp78). The antibody activity remained after immunoabsorption by human liver-specific lipoprotein (LSP) but decreased when HepG2 cells were pre-treated with trypsin or neuraminidase. Consequently, gp78 appears to be a glycoprotein distinct from LSP, and is specifically recognized by IgG from patients with alcoholic liver diseases. This assay may provide a new system to measure autoantibody to hepatocytes in alcoholic liver diseases.

Ethanol inhibits asialoglycoprotein receptor synthesis but augments its mRNA expression in a human hepatoma cell line

The effect of ethanol on the expression of asialoglycoprotein receptor protein and its mRNA was studied in a human hepatoma cell line, HepG2. The number of asialoglycoprotein receptors on the cell surface was decreased to 60% of the control level, without a loss in affinity, by incubating the cells with 100 mM ethanol. The decrease in cell surface asialoglycoprotein receptors was paralleled by a decrease in total receptor numbers, including intracellular and surface receptors. The internalization of asialoglycoprotein was also diminished, to 44% of that in control cells. The decreases in cell surface receptors and total receptor numbers were partially restored by 2 mM 4-methylpyrazole, suggesting that ethanol metabolites participated in the diminution of asialoglycoprotein receptor expression. However, the steady-state expression of asialoglycoprotein receptor mRNA was increased in ethanol-treated cells and further augmented by a longer ethanol exposure. These paradoxical results, i.e., the decrease of asialoglycoprotein receptor protein and the increase of its mRNA expression, suggest that the reduction in the asialoglycoprotein receptor protein is a post-transcriptional event and that a possible feedback regulatory mechanism may control asialoglycoprotein receptor gene transcription and/or impair the degradation of its mRNA.