Colon Cancer Survival Among South Asian Americans: A Cross-Sectional Analysis of a National Dataset.

INTRODUCTION: Colon cancer (CC) is one of the most common cancers among South Asian Americans (SAAs). The objective of this study was to measure differences in risk-adjusted survival among SAAs with CC compared to non-Hispanic Whites (NHWs) using a representative national dataset from the United States. METHODS: A retrospective analysis of patients with CC in the National Cancer Database (2004-2020) was performed. Differences in presentation, management, median overall survival (OS), three-year survival, and five-year survival between SAAs and NHWs were compared. Kaplan-Meier analysis and multivariable Cox regression were used to assess differences in survival outcomes, adjusting for demographics, presentation, and treatments received. RESULTS: Data from 2873 SAA and 639,488 NHW patients with CC were analyzed. SAAs were younger at diagnosis (62.2 versus 69.5 y, P < 0.001), higher stage (stage III [29.0% versus 26.2%, P = 0.001] or Stage IV [21.4% versus 20.0%, P = 0.001]), and experienced delays to first treatment (SAA 5.9% versus 4.9%, P = 0.003). SAAs with CC had higher OS (median not achieved versus 68.1 mo for NHWs), three-year survival (76.3% versus 63.4%), and five-year survival (69.1% versus 52.9%). On multivariable Cox regression, SAAs with CC had a lower risk of death across all stages (hazard ratio: 0.64, P < 0.001). CONCLUSIONS: In this national study, SAA patients with CC presented earlier in life with more advanced disease, and a higher proportion experienced treatment delay compared to NHW patients. Despite these differences, SAAs had better adjusted OS than NHW, warranting further exploration of tumor biology and socioeconomic determinants of cancer outcomes in SAAs.

Differential analysis of histopathological and genetic markers of cancer aggressiveness, and survival difference in EBV-positive and EBV-negative prostate carcinoma.

Several studies have shown an association between prostate carcinoma (PCa) and Epstein-Barr virus (EBV); however, none of the studies so far have identified the histopathological and genetic markers of cancer aggressiveness associated with EBV in PCa tissues. In this study, we used previously characterized EBV-PCR-positive (n = 39) and EBV-negative (n = 60) PCa tissues to perform an IHC-based assessment of key histopathological and molecular markers of PCa aggressiveness (EMT markers, AR expression, perineural invasion, and lymphocytic infiltration characterization). Additionally, we investigated the differential expression of key oncogenes, EMT-associated genes, and PCa-specific oncomiRs, in EBV-positive and -negative tissues, using the qPCR array. Finally, survival benefit analysis was also performed in EBV-positive and EBV-negative PCa patients. The EBV-positive PCa exhibited a higher percentage (80%) of perineural invasion (PNI) compared to EBV-negative PCa (67.3%) samples. Similarly, a higher lymphocytic infiltration was observed in EBV-LMP1-positive PCa samples. The subset characterization of T and B cell lymphocytic infiltration showed a trend of higher intratumoral and tumor stromal lymphocytic infiltration in EBV-negative tissues compared with EBV-positive tissues. The logistic regression analysis showed that EBV-positive status was associated with decreased odds (OR = 0.07; p-value < 0.019) of CD3 intratumoral lymphocytic infiltration in PCa tissues. The analysis of IHC-based expression patterns of EMT markers showed comparable expression of all EMT markers, except vimentin, which showed higher expression in EBV-positive PCa tissues compared to EBV-negative PCa tissues. Furthermore, gene expression analysis showed a statistically significant difference (p < 0.05) in the expression of CDH1, AR, CHEK-2, CDKN-1B, and CDC-20 and oncomiRs miR-126, miR-152-3p, miR-452, miR-145-3p, miR-196a, miR-183-3p, and miR-146b in EBV-positive PCa tissues compared to EBV-negative PCa tissues. Overall, the survival proportion was comparable in both groups. The presence of EBV in the PCa tissues results in an increased expression of certain oncogenes, oncomiRs, and EMT marker (vimentin) and a decrease in CD3 ITL, which may be associated with the aggressive forms of PCa.

Risk stratification and outcomes in 210 gynecologic perivascular epithelioid cell tumors (PEComas) cases.

OBJECTIVE: To better understand the risk stratification and outcomes of gynecologic PEComas. METHODS: Clinicopathological features and outcomes of gynecologic PEComas cases reported in both English and Chinese literature before September, 2020 were evaluated. The efficacy of three proposed criteria were compared to verify their practicability in gynecologic PEComas. The Chi-square test and Cox proportional hazard model were performed for statistical analysis. RESULTS: A total of 210 cases were retrieved: 95 from English literature and 115 from Chinese literature. The Flope criterion achieved an accuracy of 47% for detecting malignancy of gynecologic PEComas, 64.2% for the Schoolmeester criterion, and 63.8% for the WHO criterion. Both Chi-square test and uni-variate analysis showed that tumor size ≥ 5 cm, infiltrative growth pattern, mitotic rate ≥ 1/50 high per filed (HPF), high nuclear grade and cellularity, necrosis, and vascular invasion were significantly related to recurrence and/or metastasis (R/M) of gynecologic PEComas. Still only high mitotic rate (≥ 1/50 HPF), high nuclear grade and cellularity, and necrosis significantly influenced the long-term survival. Multi-variate analysis showed high nuclear grade and cellularity was an independent risk factor for R/M of gynecologic PEComas. No model was fitted for the death rate due to a small number of events. When defined malignant PEComas cases as meeting three or more out of six clinicopathologic features, the accuracy of such attempt was 62%, but the false-negative rate dropped by 37-55%. CONCLUSIONS: Gynecologic PEComas with three or more high-risk factors may be considered as malignant. Further efforts should be invested to look for new potential prognostic factors.

Detection and characterization of latency stage of EBV and histopathological analysis of prostatic adenocarcinoma tissues.

The pathophysiology of prostate cancer involves both genetic and acquired factors, including pathogens, such as viruses. A limited number of studies have shown the presence of Epstein-Barr virus (EBV) in prostate cancer tissues. However, there is a dearth of data exploring EBV latency profile in prostate cancer, and the relationship of EBV with histopathological features of prostate cancer. In this study, prostate cancer and benign prostatic hyperplasia (BPH) samples were screened for the presence of EBV, followed by the characterization of the EBV latency profile and analysis of histopathological parameters in EBV-positive and EBV-negative groups. A conventional PCR strategy was employed using virus-specific primers to screen EBV in 99 formalin-fixed paraffin-embedded (FFPE) prostate cancer and 33 BPH samples received for histopathological analysis during the years 2019-2020. Subsequently, cDNA samples were used in a qPCR array to analyze the expression of EBV latency-associated genes to map the latency profile EBV maintains in the samples. Finally, statistical analyses were performed to determine the correlation between EBV and several histopathological features of the samples. EBV was detected in 39% of prostate cancer and 24% of BPH samples. The histopathological analysis of prostate cancer samples identified all samples as prostatic adenocarcinoma of acinar type, while statistical analyses revealed EBV-positive samples to exhibit significantly higher (p < 0.05) Gleason major and total Gleason scores as compared to EBV-negative samples. In the EBV-positive samples, variable expression patterns of latency-associated genes were observed, where most of the samples exhibited EBV latency II/III-like profiles in prostate cancer, while latency-II-like profiles in BPH samples. This study suggests a high prevalence of EBV in prostate samples, where EBV exhibited latency II/III-like profiles. Furthermore, EBV-positive samples exhibited a higher Gleason score suggesting a possible link between EBV and the onset/progression of prostate cancers. However, future functional studies are required to understand the role of the EBV gene expression profile in the onset/progression of prostate cancer.

MicroRNAs as Potential Biomarkers for Exercise-Based Cancer Rehabilitation in Cancer Survivors.

Expression and functions of microRNAs (miRNAs) have been widely investigated in cancer treatment-induced complications and as a response to physical activity, respectively, but few studies focus on the application of miRNAs as biomarkers in exercise-based cancer rehabilitation. Research has shown that certain miRNA expression is altered substantially due to tissue damage caused by cancer treatment and chronic inflammation. MiRNAs are released from the damaged tissue and can be easily detected in blood plasma. Levels of the miRNA present in peripheral circulation can therefore be used to measure the extent of tissue damage. Moreover, damage to tissues such as cardiac and skeletal muscle significantly affects the individual's health-related fitness, which can be determined using physiologic functional assessments. These physiologic parameters are a measure of tissue health and function and can therefore be correlated with the levels of circulating miRNAs. In this paper, we reviewed miRNAs whose expression is altered during cancer treatment and may correlate to physiological, physical, and psychological changes that significantly impact the quality of life of cancer survivors and their role in response to physical activity. We aim to identify potential miRNAs that can not only be used for monitoring changes that occur in health-related fitness during cancer treatment but can also be used to evaluate response to exercise-based rehabilitation and monitor individual progress through the rehabilitation programme.

Level I Nodal Positivity as a Factor for Involvement of the Submandibular Gland in Oral Cavity Carcinoma: A Case Series Report.

Introduction The routine practice of neck dissection in the surgical management of oral carcinoma has evolved into a more functionally conservative approach. Over time, the rationale for removal of the submandibular gland has been questioned. Routine extirpation of the submandibular gland can aggravate the xerostomia experienced by many patients, significantly affecting their quality of life. Objective The objective of the present study was to determine the incidence of submandibular gland metastases in oral cavity carcinoma and to identify possible factors that may affect their involvement. Methods A total of 149 cases of oral carcinoma presenting at a private tertiary care hospital in Karachi, Pakistan, over the course of 1 year were reviewed retrospectively. Results Histopathological data showed that the submandibular gland was involved in 7 (4.7%) cases. Involvement of level I lymph nodes was found in all of the cases. Direct extension of primary tumor was noted in two cases when the primary tumor was in the floor of the mouth. Conclusion The results suggest that preservation of the submandibular gland during neck dissection for oral carcinoma can be practiced safely when there is no evidence of direct extension of the primary tumor toward the submandibular gland or when there is no clinical or radiological evidence of neck disease in level I. Presence of pathological lymph nodes in level I requires caution when contemplating preservation of the submandibular gland.

Level I Nodal Positivity as a Factor for Involvement of the Submandibular Gland in Oral Cavity Carcinoma: A Case Series Report

Abstract Introduction The routine practice of neck dissection in the surgical management of oral carcinoma has evolved into a more functionally conservative approach. Over time, the rationale for removal of the submandibular gland has been questioned. Routine extirpation of the submandibular gland can aggravate the xerostomia experienced by many patients, significantly affecting their quality of life. Objective The objective of the present study was to determine the incidence of submandibular gland metastases in oral cavity carcinoma and to identify possible factors that may affect their involvement. Methods A total of 149 cases of oral carcinoma presenting at a private tertiary care hospital in Karachi, Pakistan, over the course of 1 year were reviewed retrospectively. Results Histopathological data showed that the submandibular gland was involved in 7 (4.7%) cases. Involvement of level I lymph nodes was found in all of the cases. Direct extension of primary tumor was noted in two cases when the primary tumor was in the floor of the mouth. Conclusion The results suggest that preservation of the submandibular gland during neck dissection for oral carcinoma can be practiced safely when there is no evidence of direct extension of the primary tumor toward the submandibular gland or when there is no clinical or radiological evidence of neck disease in level I. Presence of pathological lymph nodes in level I requires caution when contemplating preservation of the submandibular gland.

The Role of K-Ras and P53 in Biliary Tract Carcinoma.

OBJECTIVE: To focus mainly on the role of proto-oncogene Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (K-Ras) and tumour-suppressor gene p53 which are among the most commonly mutated genes in biliary tract carcinomas. METHODS: The systematic review comprised research articles published between 2002 and 2019 on PubMed and Google Scholar databases which were searched using the terms 'TP53', 'K-Ras', 'mutation', 'biliary tract carcinoma', 'cholangiocarcinoma', and 'murine model'. Repetitions, duplicates and irrelevant articles were excluded. No data was retrieved from posters, presentations and symposiums, and experiments involving bile aspirations were also excluded. RESULTS: Of the 72 articles reviewed, 11(15.3%) were included. Of them, 3(27.3%) studies, conducted in China, Japan and Taiwan, reported a positive correlation between K-Ras mutation and biliary tract carcinoma. Only 1(9%) study, conducted in China, showed the sole correlation between p53 inactivation and biliary tract carcinoma. Also, 4(36.4%) studies, conducted in China, Japan and Europe, showed a positive association of both K-Ras mutation and p53 inactivation with biliary tract carcinoma. CONCLUSIONS: K-Ras and p53 mutation both contribute to biliary tract carcinoma. K-Ras mutation, however, has a much higher frequency compared to p53 inactivation in such cancers.

Genetic aberrations involved in relapse of pediatric acute myeloid leukemia: A literature review.

Globally, 15-20% of all children diagnosed with leukemia suffer from acute myeloid leukemia (AML), a rapidly progressive, clinically and biologically heterogeneous disease leading to the impaired differentiation of myeloid blast cells. Although 80% of patients achieve complete remission after induction chemotherapy, many relapse, negatively affecting overall out comes. The mechanisms underlying relapse have not been fully elucidated. This review aims to provide an overview of genetic aberrations involved in relapse of disease. A literature review on molecular mechanisms implicated in pediatric AML relapse spanning from 2003 to 2017 was conducted. PubMed, Medline, and Google Scholar were interrogated using relevant search terms. Of note, we examined a total of final 10 research papers from four large study groups that have utilized whole genome sequencing and molecular targeting of trio or paired samples of initial diagnosis, remission, and relapse. Their findings reveal that the genomic landscape of pediatric AML varies from diagnosis to relapse in different populations. Pediatric AML relapse is a systemic evolutionary illness accompanied by synchronized mutational hits impairing differentiation function. The irregular proliferative function is a consequence of mutations in signal transduction genes such as FLT3, RAS, PTPN11, and c-KIT and genes that code for transcription factors such as CEBPα, WT1, SATB1, GFI1, KLF2, and TBP are associated with relapse of disease. Identification of molecular markers unique to different stages of the disease in distinct populations can provide valuable information about disease prognosis and management.

Mutational landscape of head and neck squamous cell carcinomas in a South Asian population.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer type globally and contributes significantly to burden of disease in South Asia. In Pakistan, HNSCC is among the most commonly diagnosed cancer in males and females. The increasing regional burden of HNSCC along with a unique set of risk factors merited a deeper investigation of the disease at the genomic level. Whole exome sequencing of HNSCC samples and matched normal genomic DNA analysis (n=7) was performed. Significant somatic single nucleotide variants (SNVs) were identified and pathway analysis performed to determine frequently affected signaling pathways. We identified significant, novel recurrent mutations in ASNS (asparagine synthetase) that may affect substrate binding, and variants in driver genes including TP53, PIK3CA, FGFR2, ARID2, MLL3, MYC and ALK. Using the IntOGen platform, we identified MAP kinase, cell cycle, actin cytoskeleton regulation, PI3K-Akt signaling and other pathways in cancer as affected in the samples. This data is the first of its kind from the Pakistani population. The results of this study can guide a better mechanistic understanding of HNSCC in the population, ultimately contributing new, rational therapeutic targets for the treatment of the disease.

Microbiological safety of areca nut-containing, ready-to-eat chewing substances common among Pakistani paediatric population: A pilot study.

OBJECTIVE: To evaluate microbiological contamination of areca nut-containing, ready-to-eat chewing substances easily accessible to vulnerable paediatric population. METHODS: A pilot study was conducted at the Aga Khan University Medical College from June to October 2016 on twelve samples of areca nut-containing chewing substances (four supari, paan masala and gutka each) collected from various localities of Karachi. These were evaluated individually for total colony counts, hygiene indicator organisms, pathogenic organisms, and levels of aflatoxin. Microbial contamination was analysed using pour-plate method. Fungal aflatoxin levels were measured by enzyme-linked immunosorbent assay (ELISA).. RESULTS: Wet gutka preparations were contaminated by Escherichia coli and Enterobacteriacaea. High levels of fungal aflatoxin (range: 0.43-1.84 mg/kg), a proven carcinogen, were identified in all the 12(100%) products. No sample contained pathogenic bacteria. However, 1(8.33%) sample did not meet hygiene criteria cut-off. CONCLUSIONS: Habitual use of unhygienic chewing substances containing fungal toxins is a public health concern that needs to be addressed through a preventative, behaviour-changing strategy..

Viral etiology of prostate cancer: Genetic alterations and immune response. A literature review.

Prostate cancer is one of the most common cancers in men. Recent estimates suggest that over a million men are diagnosed with the disease annually. Prostate cancer pathogenesis involves both heritable and environmental factors. The molecular events involved in the development or progression of prostate cancer are still unclear. Recent body of literature highlights the role of viral infections in initiation or progression of prostate cancer. In this regard, certain viruses have been reported to interact with host proteins and bring about changes in genetic, immunological and inflammatory events that lead to initiation or progression of prostate cancer. We conducted a comprehensive PubMed database search to identify publications relevant to viruses associated with prostate cancer. In this review, we discuss the possible viral etiology of prostate cancer and evidence of viral-mediated genetic changes, and immune dysregulation involved in initiation or progression of prostate cancer.

DNA methylation as an epigenetic regulator of gallbladder cancer: An overview.

Gallbladder cancer (GBC) is a lethal health issue affecting mostly the women in their middle-age. High incidence of GBC has been reported across the world specifically in Asian countries, India and Pakistan. The exact etiology remains unknown, although several risk factors and genetic aberrations involving mutations or epigenetic changes may be involved in gallbladder carcinogenesis. This article presents a review of the published literature mainly from the year 2003 onwards. The topic of main concerns was epigenetic regulation of GBC. All relevant studies identified were included and are described according to the aforementioned subheadings. In this review, we have discussed the role of DNA methylation in GBC, clinical implication and future prospects of biomarker development for early diagnosis and therapeutic interventions.

Sporadic Early Onset Colorectal Cancer in Pakistan: a Case- Control Analysis of Microsatellite Instability.

BACKGROUND: Early onset sporadic colorectal cancer (CRC) is a biologically and clinically distinct entity hypothesized to exhibit differences in histological features and microsatellite instability (MSI) as compared to typical onset CRC. This study compared the MSI status, mismatch repair enzyme deficiency and clinicopathological features of early onset (aged ≤45 years) with controls (>45 years). MATERIALS AND METHODS: A total of 30 cases and 30 controls were analyzed for MSI status using the Bethesda marker panel. Using antibodies against hMLH1, hMSH2 and hMSH6, mismatch repair protein expression was assessed by immunohistochemistry. Molecular characteristics were correlated with clinicopathological features. RESULTS: The early onset sporadic CRCs were significantly more poorly differentiated tumors, with higher N2 nodal involvement and greater frequency of signet ring phenotype than the typical onset cases. MSI was observed in 18/30 cases, with 12/18 designated as MSI-high (MSI-H) and 6/18 designated as MSI-low (MSI-L). In the control group, 14 patients exhibited MSI, with 7 MSI-H and 7 MSI-L. MSI tumors in both cases and controls exhibited loss of hMLH1, hMSH2 and hMSH6. MSS tumors did not exhibit loss of expression of MMR proteins, except hMLH1 protein in 3 controls. No statistically significant difference was noted in MSI status or expression of MMR proteins in cases versus controls. CONCLUSIONS: Microsatellite status is comparable between early and typical onset sporadic CRC patients in Pakistan suggesting that differences in clinicopathological features between these two subsets are attributable to other molecular mechanisms.

Colorectal cancer carcinogenesis: a review of mechanisms.

Colorectal cancer (CRC) is the second most common cancer in women and the third most common in men globally. CRC arises from one or a combination of chromosomal instability, CpG island methylator phenotype, and microsatellite instability. Genetic instability is usually caused by aneuploidy and loss of heterozygosity. Mutations in the tumor suppressor or cell cycle genes may also lead to cellular transformation. Similarly, epigenetic and/or genetic alterations resulting in impaired cellular pathways, such as DNA repair mechanism, may lead to microsatellite instability and mutator phenotype. Non-coding RNAs, more importantly microRNAs and long non-coding RNAs have also been implicated at various CRC stages. Understanding the specific mechanisms of tumorigenesis and the underlying genetic and epigenetic traits is critical in comprehending the disease phenotype. This paper reviews these mechanisms along with the roles of various non-coding RNAs in CRCs.

Clinical features and outcome of sporadic colorectal carcinoma in young patients: a cross-sectional analysis from a developing country.

Background. Early onset colorectal carcinoma (CRC) is rare and has been hypothesized to be a biologically and clinically distinct entity personifying aggressive disease and worse survival. Methods. Data for 131 patients was collected by retrospective chart review. Cox proportional hazard model was used to compute prevalence ratios and 95% confidence intervals. Results. Early onset sporadic CRC accounted for 32% of all CRC treated in the specified time period. The mean age was 33.3 ± 7.9 years and the male to female ratio was 2 : 1. Colon and rectal cancers accounted for 55% and 45% of patients, respectively. 96% of rectal carcinoma patients received appropriate therapy as opposed to 65% of colon cancers. On multivariable analysis, appropriate reception of therapy (PR 4.99; 95% CI, 1.21-20.6) and signet ring morphology (PR 2.40; 95% CI, 1.33-4.32) were significantly associated with rectal cancers as opposed to colon cancer. Kaplan-Meier analysis revealed a trend towards inferior survival for rectal carcinoma 2 years after diagnosis. Conclusion.A high prevalence of early onset CRC was noted in the study. A trend towards inferior survival was seen in patients with rectal cancer. This finding raises the possibility of rectal carcinoma being an aggressive subset of young CRC.

Juvenile nasopharyngeal angiofibroma: experience at a tertiary care centre in Pakistan.

OBJECTIVE: To review the clinical presentations of Juvenile nasopharyngeal angiofibroma surgical approaches used and outcomes of patients at an urban tertiary care centre in Pakistan. METHOD: The retrospective study was conducted at Aga Khan University Hospital, Karachi, involving medical records of patients with histologically confirmed Juvenile nasopharyngeal angiofibroma who were treated between 2000 and 2008. RESULTS: Eighteen male patients were identified, with an average age at diagnosis of 16 5.6 (range 11-28) years. Most patients (n = 16; 88.9%) presented with epistaxis. CT scan was the most common (n = 17; 94.44%) radiological investigation for staging. Blood supply of the tumour was varied (ipsilateral or bilateral internal maxillary artery). According to Andrews staging, 4 (22.22%) patients presented with stage I disease; 5 (27.77%) with stage II; 4 (22.22%) with stage IIIa; 1 (5.55%) with stage IIIb; and 4 (22.22%) with stage IVb disease. Of the 18 patients, 17 (94.44%) underwent 19 surgical procedures, with a recurrence rate of 10.5% (n=2) and incomplete resection in 15.8% (n = 3) procedures. Lateral rhinotomy was the most frequently employed (n = 13; 68.42%) surgical approach in the 19 surgical procedures conducted at the AKUH. CONCLUSION: Surgery continues to be the mainstay treatment modality. Surgical approach is dependent on various disease factors as well as institutional resources. In situations of limited resources, the condition may still be managed effectively with traditional approaches that result in good functional outcome and low morbidity.

Enzastaurin (LY317615), a protein kinase Cbeta inhibitor, inhibits the AKT pathway and induces apoptosis in multiple myeloma cell lines.

Enzastaurin (LY317615), an acyclic bisindolylmaleimide, is an oral inhibitor of the protein kinase Cbeta isozyme. The objective of this study was to assess the efficacy of enzastaurin in inducing apoptosis in multiple myeloma (MM) cell lines and to investigate possible mechanisms of apoptosis. Cell proliferation assays were done on a variety of MM cell lines with unique characteristics (dexamethasone sensitive, dexamethasone resistant, chemotherapy sensitive, and melphalan resistant). The dexamethasone-sensitive MM.1S cell line was used to further assess the effect of enzastaurin in the presence of dexamethasone, insulin-like growth factor-I (IGF-I), interleukin-6, and the pan-specific caspase inhibitor ZVAD-fmk. Enzastaurin increased cell death in all cell lines at clinically significant low micromolar concentrations (1-3 micromol/L) after 72 hours of treatment. Dexamethasone and enzastaurin were shown to have an additive effect on MM.1S cell death. Although IGF-I blocked the effect of 1 micromol/L enzastaurin, IGF-I did not abrogate cell death induced with 3 mumol/L enzastaurin. Moreover, enzastaurin-induced cell death was not affected by interleukin-6 or ZVAD-fmk. GSK3beta phosphorylation, a reliable pharmacodynamic marker for enzastaurin activity, and AKT phosphorylation were both decreased with enzastaurin treatment. These data indicate that enzastaurin induces apoptosis in MM cell lines in a caspase-independent manner and that enzastaurin exerts its antimyeloma effect by inhibiting signaling through the AKT pathway.

8-Amino-adenosine induces loss of phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase 1/2, and Akt kinase: role in induction of apoptosis in multiple myeloma.

Multiple myeloma is a slowly proliferating B-cell malignancy that accumulates apoptosis-resistant and replication-quiescent cell populations, posing a challenge for current chemotherapeutics that target rapidly replicating cells. Multiple myeloma remains an incurable disease in need of new therapeutic approaches. The purine nucleoside analogue, 8-amino-adenosine (8-NH2-Ado), exhibits potent activity in preclinical studies, inducing apoptosis in several multiple myeloma cell lines. This cytotoxic effect requires phosphorylation of 8-NH2-Ado to its triphosphate form, 8-amino-ATP, and results in a concomitant loss of endogenous ATP levels. Here, we show the novel effect of 8-NH2-Ado on the phosphorylation status of key cellular signaling molecules. Multiple myeloma cells treated with 8-NH2-Ado exhibit a dramatic loss of phosphorylation of several important signaling proteins, including extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and Akt kinase. Cells depleted of ATP independent of 8-NH2-Ado do not exhibit the same decrease in phosphorylation of vital cellular proteins. Therefore, the significant shifts in endogenous ATP pools caused by 8-NH2-Ado treatment cannot account for the changes in phosphorylation levels. Instead, 8-NH2-Ado may influence the activity of select regulatory protein kinases and/or phosphatases, with preliminary data suggesting that protein phophatase 2A activity is affected by 8-NH2-Ado. The distinctive effect of 8-NH2-Ado on the phosphorylation status of cellular proteins is a novel phenomenon for a nucleoside analogue drug and is unique to 8-NH2-Ado among this class of drugs. The kinetics of 8-NH2-Ado-mediated changes in phosphorylation levels of critical prosurvival and apoptosis-regulating proteins suggests that the modulation of these proteins by dephosphorylation at early time points may be an important mechanistic step in 8-NH2-Ado-induced apoptosis.

Caspase activation is required for gemcitabine activity in multiple myeloma cell lines.

The objective of this study was to determine potential mechanisms of apoptotic activity of gemcitabine, a pyrimidine nucleoside analogue, in the MM1.S multiple myeloma (MM) cell line. A MM cell line that is sensitive to glucocorticoids (MM1.S) was used for this study. Immunoblotting analysis, cell cycle assays, and annexin V staining were performed to determine whether gemcitabine induced apoptosis in this model. Furthermore, we attempted to delineate the apoptotic pathway by measuring caspase-8 and -9 activity using fluorometric assays. Loss of mitochondrial membrane potential was measured by flow cytometry. Gemcitabine treatment caused apoptosis in MM cell lines as measured by an increase in DNA cleavage, an increase in annexin V binding, a decrease in the mitochondrial membrane potential, and activation of caspase activity. Furthermore, cleavage of the caspase substrate poly(ADP-ribose) polymerase and caspase-3 activation were documented as early as 8 h after treatment with gemcitabine. Caspase-8 and -9 were activated by gemcitabine treatment in this cell line, suggesting several mechanisms of action including death receptor pathway and mitochondrial damage. The addition of interleukin 6 to MM1.S cells treated with gemcitabine offered no protection against gemcitabine-induced cell death. Gemcitabine induced apoptosis in the MM1.S cell line, and its activity required caspase activation. There is a suggestion that mitochondrial integrity is being affected with gemcitabine in this system. Gemcitabine acts independently of interleukin 6, suggesting potential important therapeutic implications in MM patients.